Friday, September 6, 2019
PHP vs. ASP Scripting Software Research Paper Essay Example for Free
PHP vs. ASP Scripting Software Research Paper Essay ABSTRACT This paper examines the differences between the ASP (Active Server Pages) and PHP (Hypertext Preprocessor) scripting languages. Both ASP and PHP are scripting languages that can be used to create dynamic web pages which are capable of interacting and exchanging information with databases. ASP is a Microsoft product, and is used with Internet Information Server (IIS) which runs on Microsoft Servers. PHP was originally designed by Rasmus Lerdorf, and was later modified by various people. As a parsing language, PHP can run both on Unix and Linux servers, and also has a version that runs on an NT server. This paper also discusses the differences in cost, speed, integration of features, speed, additional costs, base language, database connectivity and Platform Compatibility between both languages. This paper also presents some suggestions offer recommendations as to when one of these languages should be preferred over the other, and how efficiency can be maximized in the usage of each of these scripting languages Introduction             ASP and PHP are both website design scripting languages that are processed by backend severs like Apache Server and Windows OS. Apache Server is usually used for PHP and a Windows OS with IIS Server is used to process ASP scripted websites. PHP processed website scripts can also be processed by UNIX OS backend servers, while Window OS IIS backend servers are used to process ASP scripts. ASP.NET is part of the .NET Framework and is the core technology for developing web applications and XML Web Services. ASP.NET is a compiled, .NET-based environment; you can author applications in any .NET compatible language, including Visual Basic .NET, C#, and JScript .NET. Additionally, the entire .NET Framework is available to any ASP.NET application. Developers can easily access the benefits of these technologies, which include the managed common language runtime environment, type safety, inheritance, and so on. .NET developers write Web Parts using Visual Studio.NET 2003. The Web Part Framework is the basis for extensibility in Windows SharePoint Services. It allows developers to write custom components that plug into the SharePoint infrastructure by encapsulating web services and enterprise data as Web Parts. Web Part Pages are special ASP.NET pages which are the building blocks of a Windows SharePoint Services based data driven web site. Web page authors can use Microsoft FrontPage 2003 to leverage Windows SharePoint Services and use the Web Part Framework to easily build data driven web sites using a library of readily available web parts. Microsoft FrontPage 2003 integrates closely with Windows SharePoint Services and is the easiest and the most powerful web site design tool that enables creation of a new category of collaborative, scalable, data driven web sites. (http://www.sharepointcustomization.com/resources/whitepapers/webpartdocs/wp_asp_net.doc)            PHP and ASP are the two best web technologies in use today. In their own ways, they have created trust and market for their product and development environment, although many people are of the opinion that PHP is an all around better choice than ASP.            According to Anstey, â€Å"PHP belongs to a free software community and open source general purpose software which is very easy to use and correct its bugs from the community of developers around the world.†(Anstey 2003). ASP runs on an IIS server and is a free component with the Microsoft windows operating system. ASP offers various useful features like type safety, inheritance, and a managed common language runtime environment.            In a broad sense, PHP is scripting Language, while ASP.NET is a Designing Tool. Also, PHP contains mainly scripting tabs, with a minimum number of controls being used, while ASP.Net has a lot of controls to the designing process.           ASP.NET is a unified Web development platform that provides services necessary for developers to build enterprise-class Web applications. ASP.NET provides programming model and infrastructure for more secure, scalable, and stable applications. ASP.NET is a compiled, .NET based web environment developed in .NET compatible languages like Visual Basic .NET, C#, JScript.NET, etc. Additionally, the entire .NET Framework is available to any ASP.NET application. Developers can easily access the benefits of this technology, which includes the managed common language runtime environment, type safety, and inheritance.             From many views and perspectives, PHP is an overall better choice than ASP. Although both ASP and PHP are languages used to build Dynamic Web sites that can interact with Databases and exchange information. ASP (Active Server Pages) is from Microsoft and is used with IIS (Internet Information Server) that runs on Microsoft Servers. PHP (PHP: Hypertext Preprocessor) is from Rasmus Lerdorf, who originally designed this parsing language which was later modified by different people. It runs on Unix and Linux servers and it also has an NT server version. (Pires, Halstatt 2005. ASP vs. PHP. Retrieved 18, February 2008 from http://www.webpronews.com/expertarticles/2005/12/22/asp-vs-php)            The foundation of all Web applications is that they deliver dynamic content over a protocol which by model is stateless. Most of the ASP.NET developments fall in client-server architecture programming model. Minimal points to be considered for a typical web application modeled as client-server architecture are given below. User interface and client environment (Page layout). Data verification, transfer and store. Security. Scalability, reliability and availability of the application. Optimized resource utilization and performance. Handling unpleasant instances gracefully. Navigation.            PHP traces back to the development of Perl and C which emerged quite successfully as a result of the contribution of the various programmers around the globe and as a result of its being an open community. The various versions came out successfully through 1997 to 2004 where the features were added and successfully taken up to cater to the development paradigm of the large scale of internet users.            ASP came handy with Windows 95 with the features of IIS server installed. It was an established standard which takes into account the various databases into consideration and is based on the COM model. The various differences among PHP and ASP make sure that all to a good extent the feature are compiled and carries enough advantage to understand the loopholes and make sure that all the various utilities are enforced well. Differences between PHP and ASP            PHP and ASP depict a large array of differences in the form of various factors. Some differences between ASP and PHP include differences in cost, speed, integration of features, speed, additional costs, base language, database connectivity and Platform Compatibility. Cost             As PHP is not singly owned by any individual or an organization, it does not require purchase before use. â€Å"PHP uses a database technology named MySQL for back-end support. MySQL is also available free of cost.†(DuBois, 2002). The hosting and deployment of PHP webpages into the Linux server is quite affordable and can be done with ease.             â€Å"ASP is synchronized with the Microsoft Windows operating system and comes along with it, thereby bearing the cost of the operating system.†(Glass 2004) Moreover, hosting ASP pages over the internet is expensive and features like email, file uploading and other features are quite expensive at the same time. PHP is free, but ASP is not free. If you want to use ASP, you have to use IIS, and if you want to use IIS, you have to buy Windows. Traditionally, the cost of Windows has been high. Microsoft has been aggressively trying to reduce this factor but theyre hardly going to give Windows away for free. The cost of running an ASP-based website implies a full Windows server platform; development costs are higher, software licenses are expensive and speed, security and flexibility are all sacrificed. (Anstey, M 2003)             To run ASP programs, one needs IIS installed on a Windows platform server, which is not free. PHP programs can run on Linux, which is free. Even the connectivity of the database is expensive in the case of ASP as MS-SQL is a Microsoft product that needs to be purchased. PHP generally uses MySQL, which is freely available.            Many of the tools used in PHP are free of charge and a lot of PHP code can be found in open source forums, because PHP is open source. â€Å"PHP also has inbuilt features like ftp, email from a web page and even encryption mechanisms but such features are not built into ASP, which requires some additional components. Therefore additional costs might be incurred for such components.†(Pires, Halstatt 2005. ASP vs. PHP. Retrieved 18, February 2008 from http://www.webpronews.com/expertarticles/2005/12/22/asp-vs-php) Speed            In terms of speed, PHP is faster than ASP, because when the speed of PHP and ASP are compared, PHP would have the upper hand. â€Å"This is due to the fact that PHP code runs faster than ASP. Also, ASP is built on COM based architecture, which is an overhead for the server, whereas PHP code runs in its own memory space.†(Pires, Halstatt 2005. ASP vs. PHP. Retrieved 18, February 2008 from http://www.webpronews.com/expertarticles/2005/12/22/asp-vs-php) Integration with operating environments and databases             PHP makes sure that all the operating environments are taken care to its fullest capability and is compatible with Windows, UNIX, Linux, Solaris and others. Its platform dependency format makes sure that all the various compatibility with operating environments makes it quite viable in nature. PHP integrates with the databases like MySQL and others in a great fashion. â€Å"ASP on the other hand is compatible with Windows only and makes sure that Microsoft oriented databases like MSSQL server would be well integrated with it. For other database platforms it requires to download various libraries and components for integration and workability.†(Hull, 2002) Performance             PHP is an interpreted language and make sure that the interpreted nature makes it fast for getting the customization done. The memory requirement of the PHP pages is quite optimizable and runs very fast with the greater understanding of the various features. Database connections of PHP are also quite flexible and make sure that all the various database functionality like stability, transactions, replication, triggers and stored procedures are handled quite well (Merrall, 2000).             ASP on the other hand is a compiled language and the software glitches are quite often not corrected or take a long time to get it done. The compiled nature makes sure that all the various factors like throughput and response time is quite low for the hosted pages. Its exclusivity with Microsoft windows operating system makes it platform independent with regard to various hosting and access problems. PHP offers the best integration of speed and performance, and ensures that all the various promises are met for catering to the web development. ASP is most suitable with the Microsoft platform and makes sure that all the features are captured and managed for the various services. (Zhang, 1999). Base Language           ASP has a type of syntax that resembles Visual Basic, and is closely related to Microsoft products. In contrast, PHP is based on the C++ language, and the syntax used for PHP looks a lot like C/C++ programming syntax. â€Å"C/C++ is still considered the best programming language by many programmers and people who love this language would surely feel more comfortable with the syntax of PHP.†(Pires, Halstatt 2005. ASP vs. PHP. Retrieved 18, February 2008 from http://www.webpronews.com/expertarticles/2005/12/22/asp-vs-php) Enhanced capabilities and compatibility               These include file transfer programs and utilities, compression of data, uploading of files, integration of XML an MD5, encryption techniques and email facilities are not included in ASP, even if it does it requires the support of large third party packages installed, which are very easily integrated in PHP. PHP.net (2008) mentions that complex functions like dynamic images, IMAP, SNMP, dynamic flash, PDF, native access to Oracle, Ovrimos, Postgre, Sybase, mSql, MSSQL, Ingres, Interbase and Informix databases, LDAP, and sockets and many others are easily integrated with PHP, â€Å"however it would create a big problem with its integration with ASP. PHP is compatible with various web servers for its functioning however ASP requires it to be easily integrated with only IIS and PWS†as explained by Pires (2005).            PHP programs can run on various platforms like Linux, Unix, Windows and Solaris whereas ASP is mainly associated with Windows platforms. However, ASP can run on a Linux platform with ASP-Apache installed on the server. PHP is based on C++ language and the syntax used in PHP is quite similar to C/C++. C/C++ is still considered the best programming language by many programmers and people who love this language would surely feel more comfortable with the syntax of PHP. ASP on the other hand has a more Visual Basic kind of syntax that again is closely related to only Microsoft products. So, it depends on the individual, and which language he or she is comfortable with.           For Database connectivity, PHP is being extremely flexible, and can connect to various databases, the most popular being MySQL. ASP mainly uses MS-SQL for databases. Conclusion             Although both ASP and PHP are good web server end languages for web development, there are some differences between them that should be considered to ensure that factors like cost, installation, performance, and compatibility issues are economized to the full extent. Both languages have advantages specific to various users. Some would argue that both languages have their own importance, and usage of either ASP or PHP depends on the users requirements, the language and the platform in use. â€Å"If a user is looking for some e-commerce application development then ASP is probably the ideal choice. This does not mean that PHP cannot provide e-commerce solutions, but a lot of people tend to choose ASP in such instances.†(Pires, Halstatt 2005). If we talk about developing a discussion board then ASP is equally capable but some people feel that the best discussion boards are developed using PHP.             While PHP offers the best integration of speed and performance, and ensures that most web development requirements are met, ASP is most suitable with the Microsoft platform, and enables features to be captured and managed for various services. References Anstey, Marty (2003). PHP vs ASP. Retrieved 19, February 2008 from             http://marty.anstey.ca/programming/php/articles/ An Architectural Introduction to Web Parts and ASP.NET A Microsoft ® Office FrontPage ®           2003 White Paper. (Retreived from    http://www.sharepointcustomization.com/resources/whitepapers/webpartdocs/wp_asp_net.doc Argence d Ricardo (2008). Web Hosting, PHP vs AS.P. Retrieved 18, February 2008 from            http://articles.topofhosting.com/web-hosting-php-asp.php DuBois, Paul (2002). MySQL Cookbook. OReilly, October 2002. Glass, Michael (2004). Beginning PHP, Apache, Hull, Sean (2002). PHP vs. ASP.NET Redux. Retrieved 18, February 2008 from           http://www.oracle.com/technology/pub/columns/hull_php2.html Merrall, Graeme (2000). PHP/MySQL Tutorial MySQL ® Web Development. Wiley Publicizing sons. ISBN: 0-7645-5744-0. PHP.net (2008). See: http://www.php.net/manual/en Pires, Halstatt (2005). ASP vs. PHP. Retrieved 18, February 2008 from           http://www.webpronews.com/expertarticles/2005/12/22/asp-vs-php Zhang, Ying (1999). Web Database Step-by-Step Guide.
Thursday, September 5, 2019
Impact ADHD and Autism on Education
Impact ADHD and Autism on Education How does ADHD and/or autism impact on the pupil, other pupils, teachers and the whole school? Introduction and Overview First, is to define ADHD and Autism: Attention Deficit Hyperactivity Disorder (ADHD) is a disorder that tampers with major parts of the brain that is related the control of a persons attention, activity and emotions which make them appear hyper or weird. ADHD can also be considered as the poor functioning and poor communication between different areas of the brain. Autism mainly appears during the first 3 years of the childs development and growth. Its in relation to routines and repetition of behaviors which range from mild to severe. It doesnt mean that autism is a damage or disease. Jaffe-Gill et al (2008) postulate that the symptoms of ADHD will show if the section of the brain which controls hyperactivity, is not fully developed or not coordinating well with the rest of the brain and therefore it is not that the child is not able to control his behavior. Autism is not purely a genetic disorder which cannot be treated but certain reactions on the genes which are indeed affected by the external environment al factors. Autism is treatable as the important part that should be understood is, if the reactions can be flipped on, they can be as well be flipped off. Secondly, ADHD and Autism affect children and the signs and symptoms expose themselves in many different forms. The three major areas which most of the symptoms are categorized in are; in attention, hyperactivity and impulsivity. It becomes clinical when the impulsiveness and hyperactivity go beyond the social norms. The child may have difficulty in paying attention, may be fidgety, gets easily distracted, may not be able to sit still, may have difficulty in doing homework, chores around the house, or may be disorganized. Consequently, the hyperactive-impulsive type AHDH symptoms include; being always ‘on the go, struggles to wait in line, always fidgeting or squirming, running or climbing in excess, Struggles to remain seated, Blurts out answer before hearing question, talks too much, Struggles with interrupting or intruding and lastly they cannot play quietly. The last of the AHDH types is the combined type. This is the common of the three and it is a combination of the inattentive type and the hyperactive-impulsive type. Before a parent or teacher gets to establish an AHDH case, they may feel that the child is acting out or seeking attention. Without medication or/and behavioural therapy a child struggles to control his or her behaviour. Other signs of ADHD are shown when the child gets so disruptive or fidgety in class that interferes with the teacher as she tries to teach the other students, the student blurt out answers in class, the student find sit hard to wait for his turn in the line, the child also becomes so hyperactive that he cannot sit through a session for instance, the church service or watching a movie. With autism the three core areas that are involved or show the signs of the disorder include; social-not socially interacting with the environment and just being by themselves, communication which is manifested by the age of 3 when a delay in speech is eminent, and repetitive movements or limited interest. Fact file on ADHD There are various facts about Autism and ADHD: On ADHD, it affects between 5 to 10% of the school going children and affects more boys than girls about 3 to 4 times more, another fact is that 50 to 60 % of the children will continue to experience the symptoms throughout to adulthood, the ones which need pediatric prescriptions are about 78%. Many cases of ADHD are reported worldwide, especially those that affect children below the age of 3 years (Fuller, 2008). This is the year that is said to be when Autism and ADHD manifest and begin to show up prominently. On Autism; 1 in every 150 children are diagnosed with autism while 1 in every 94 boys has the disorder. It is further evident that each day, about 67 children are diagnosed with the Autism disorder and a new case is reported every 20 minutes. In comparison to AIDS, diabetes, cancer, it is further true according to statistics that more children will be diagnosed with autism this shows that it is the most rapidly growing acute developmental disability in the U.S. boys are expected to have autism four times more. There is neither cure nor medical detection for autism. Since ADHD and Autism affect the school going children, and they spend at least eight hours everyday in school, the teachers and students are more likely to observe the change in behaviors in the students and hence a big impact will be felt within the school and its environment. This document will look at the impacts of autism on pupil, on other pupils, on teachers and on the whole school. Impact of Autism on Pupil Children with severe speech difficulties finding it difficult to communicate may become very frustrated. They may be reluctant to communicate or may refuse to do so at all. If required to communicate, they may show signs of intense stress or anxiety. The child may have low self esteem and may feel rejected by peers (and may in fact be rejected by some). In such circumstances, it may become difficult to recognize that. Without support, the child may develop behavioral, emotional and social difficulties. This appears to be supported by evidence of communication problems among population such as children in care and pupils in school. Because of their dependence on structure, major problems can arise for children with autism outside lesson times. Although breaks from lessons are designed to provide normal children with the opportunities they need to relax and to interact with their peers, for a child with autism such period can be extremely stressful, children who are able to behave quite acceptably when involved in guided and structured activities frequently appear much more ‘odd or unusual at times of free play. Stereotyped and ritualistic behaviors may become more apparent and exposure to teasing or bullying is much more of a risk, especially because staff supervision at such times is greatly reduced. Break times are designed to reduce the pressure from the children not increase and therefore by allowing the children with autism to go for the break will just increase the amount of pressure in them thus it would be good if they are not allowed to go but instead relax in class by themselves without any disturbance. School meals can be another source of difficulty and it is clear from personal accounts that having to tolerate the noise and smells of meals in a crowded school canteen can be almost akin to torture for individuals with autism. Been forced into close proximity with other students, or made to eat food of particular textures or mixed together on the plate (many individuals cannot bear separate items of food touching each other) can be extremely stressful. Clare Sainsbury writes: (the potential of making mistakes (and the anxiety caused by fear of making mistakes) is enormous. One of my most vivid memories of secondary schools is been hauled out of the lunch queue by one of the dinner ladies shouting angrily, and made to stand to one side; she refused to tell me why. Only after I had burst into tears was I allowed back†¦.nobody ever explained what I had done wrong†¦.and to this day I still have no idea.) A quiet corner in which to eat, being allowed to eat slightly earlier or later than other pupils, or being permitted to bring sandwiches are among the simple solutions that can transform a nightmare into a practicable tolerant activity. If the principal problem is lack of knowledge of what to do when the basic rules can be explained simply and discreetly- beforehand. Games and extracurricular lessons are also frequent causes of stress for pupils with autism, who may lack the motor coordination, the ability to follow rapid instructions or unwritten rules and the social reciprocity required in order to contribute to these activities in any useful way. Competitive sports are a particular problem and are probably best avoided altogether, both for the sake of the person with autism and the rest of the class. However, physical fitness can be improved by encouraging activities that improve body awareness and coordination such as yoga, swimming, golf, walking or gymnastics if sensitively taught. Impact of Autism on Other Pupils The impact of Autism on other pupils can be as a result of the reaction of the children affected by Autism (Autistics). Due to the hyperactivity, in them, the other pupils will develop fear in them as they will seem as a threat to them. For instance, if a child is the kind who throws things around when annoyed, will make his classmates scream, run away, there may be accidents in that a child can be hit by the furniture or the object thrown around. Autistics are also known to be bright and understand things so fast, besides their self esteem was lowered by other students, they can also lower other pupils self esteem in academics especially. This is so because the weaker ones will be teased by them and feel threatened instead. In many cases, if the teacher does not realize this early enough, she may have ea tendency of rushing through the syllabus since of the assumption that if one or two pupils have understood what is been taught, the rest will learn from them. For some children this lack of understanding may result in a refreshing acceptance of the child with autism for the person they are. However, some children may be fearful and this may result in ostracizing, bullying, or mocking the children with autism (Kinsley, 2008). These attitudes create a matrix of difficulties for the child with the disorder which exacerbates their already significant impairments in forming peer relationships. Impact of Autism on Teachers According to Folin and Lian (2008), a teachers attitude towards pupils with Autism is directly related to the knowledge and understanding of the condition. Consequently, there is a need to develop systems and means by which knowledge and understanding about Autism are share with other colleagues. Understandably, we are in competition with multitude of other demands on professionals and, therefore, need to promote information, in an accessible and manageable form which is tailored to the context they are working in. the depth of knowledge required might lie on a continuum from awareness to expertise by the role they perform. Colleagues whose only contact with pupils with autism is during break times or assemblies will need a different level of understanding to those colleagues who may share the same teaching space. Similarly, these colleagues needs will differ again from the people primarily responsible for the teaching of youngsters with Autism. Responding to this continuum of profe ssional development need, the training portfolio may include: Informal approaches, inset days, outreach, accredited courses, and resources. Each of these depends upon practitioners within the field promoting the cause of pupils with the disorder in a positive and proactive manner. Impact of Autism on the Whole School A major impact in the whole school would be loosing children due to parents transferring their children to other schools because of various reasons such bullying. There has been case from various schools of major bullying taking place within the school; educators and society are concerned about the violent attacks in the schools (Schultz, n.d.). It is imperative that there should be a school-wide bullying prevention programs. This program will be specially tailored to address all issues that come along with the ADHD and Autism pupils. Bullying is pervasive, in the schools and adults ought to be at the forefront in bullying. This is basically because a lot of pupils will lose out especially if they are bullied until it affects their academics. It is further recommended that the right academic modification as well as academic adaptation is incorporated into the school program. The law generally requires that every child should be provided with proper and a safe learning environment. Every school should thus have the facilities for special education of the children with Autism. Compliance to these standards should be ensured on a constant basis. Conclusion ADHD and Autism are disorders that affect parts of the brain. They are not purely genetic and can be controlled. Measures should be taken to create a good environment for both the children that need special attention and the other children and also the school environment. ADHD and Autism therefore affects the childrens ability to learn. This in itself means that there are various learning activities that the students with Autism will have to miss out on, thus impacting negatively on their performance in class. Whenever the class performance deeps, the schools overall performance will also dip in a similar fashion. To sum it up, the pupil with ADHD and Autism will learn slowly thus impeding their ability to keep up to pace with the rest. Their performance will also be negative with minimal or negative advancement. Similarly, the other pupils will find it difficult to be taught at the same pace as the pupil with ADHD and Autism (Sprinkle, 2004). When their learning is affected, they will have to also exhibit withdraw signs as well as lose interest in the subject being taught. On the other hand, the teachers will find it very strenuous so that they will develop an attitude that will affect their teaching patterns. Eventually this translates into poor school performance and loss of reputation as a result. Therefore, the school will suffer from adverse publicity from the critics. Likewise, the school will be compelled to expend large sums of money in setting up a unit specially meant for the ADHD and Autism pupils. References Folin, C., Lian, M.J. (2008). Reform, inclusion, and teacher education: towards a new era of special education in the Asia-Pacific region. New York: Routledge. Retrieved October 06, 2009 from http://books.google.co.ke/books?id=X0rfLl87vkcCprintsec=frontcoversource=gbs_navlinks_s#v=onepageq=f=false Fuller, J. (2008). How to Use Behavior Modifications to Treat Childhood ADHD. eHow. Retrieved October 06, 2009 from http://www.ehow.com/how_4607436_behavior-modifications-treat-childhood-adhd.html Jaffe-Gill, E., Smith, M., Segal, R., Segal, J. (2008). Behavior Therapy for ADD/ADHD. Retrieved October 06, 2009 from http://www.vaxa.com/behavioral-treatment-adult.cfm Kinsley, R.S. (2008). What Is ADHD? KidsHealth.com. Retrieved October 06, 2009 from http://kidshealth.org/PageManager.jsp?dn=KidsHealthlic=1ps=107cat_id=146article_set=21612 Schultz, J.J. (n.d.). Behavior Modification Instead of Medication? Retrieved October 06, 2009 from http://school.familyeducation.com/add-and-adhd/medical-treatment/42677.html Sprinkle, N. (2004). ADHD Behavior Therapy: Promoting Discipline Focus in Kids. Additudemag.com. Retrieved October 06, 2009 from http://www.additudemag.com/adhd/article/860.html
Wednesday, September 4, 2019
Conflict In Horn Of Africa Causes And Solutions History Essay
Conflict In Horn Of Africa Causes And Solutions History Essay The conflict in horn of Africa has been going on for centuries. Many people lost their lives due to the unsolved territorial problems between Ethiopia and Somalia and between Ethiopia and Eretria. As we know those countries engaged in a fierce war with each other for quit long period of time which prompted a lot of suffering among the populations of those countries. One might be asking what the cause of this conflict is and why it is so difficult to solve the disputes in a peaceful means and manner. I shall discuss and answer such questions concerning these issues in the following chapters, and I shall write about the root causes of the conflict both historically and politically. In this assignment I will concentrate merely on two countries and they are Somalia and Ethiopia. .Reason for the selection of the topic The main reason which I chose this topic is to illuminate the issue of horn of Africa (Somalia and Ethiopia), in terms of political and social problems caused by a bitter and prolonged war which, the international media, rarely cover its root causes and eventually Ill suggest some ideas which might be important if it is to solve the problem between the countries for good. Problem: What is the reason that the countries in horn of Africa (Ethiopia and Somalia) engaged a fierce war with each other? 2.0. A short background of Somalia Somalia locates in horn of Africa and many Somali people are nomads who move from place to another to get a green pasture for their animals. Somalis are homogeneous people who share same language, culture and religion Somalia. As it is the case in many African countries, Somalia is colonized by British in North Somalia and Italia in south, better known as British Somaliland, Italian Somaliland and French Somaliland (modern Djibouti). The colonizers not only divided Somalia but also annexed western part of Somalia territory (known as Ogaden) to Ethiopia while they gave south western part of Somalia territory (known as NFD) to Kenya. This divide and rule approach caused tremendous war and conflict among the neighboring nations for many years. The war in 1960,s and 1970,s between the two countries attracted the attention of the world Britain withdrew from British Somaliland in 1960 to allow its protectorate to join with Italian Somaliland and form the new state of Somalia. In 1969, a coup headed by Mohamed SIAD Barre led an authoritarian socialist rule that managed to impose a degree of stability in the country for a couple of decades. One of the main successes achieved by Siad Barre in his term was the orthography or writing of Somali language for the first in Somalia history. After the regimes collapse early in 1991, Somalia descended into chaos and factional fighting, and turmoil. In May 1991, northern clans declared an independent Republic of Somaliland that now includes the administrative regions of Awdal, Waqooyi Galbeed, Togdheer, Sanaag, and Sool. Although not recognized by the international, this region has maintained a quit stability in comparison with the south of the country and continues efforts to get recognition by establishing a constitutional democracy, including holding municipal, parliamentary, and presidential elections. 2.1. Short background of Ethiopia Ethiopia is in east-central Africa, bordered on the west by the Sudan, the east by Somalia and Djibouti, the south by Kenya, and the northeast by Eritrea. The Blue Nile rises in the northwest and flows in a great semicircle before entering the Sudan. Its chief reservoir, Lake Tana, lies in the northwest. Fascist Italy invaded Ethiopia on Oct. 3, 1935, forcing Haile Selassie into exile in May 1936. Ethiopia was annexed to Eritrea, then an Italian colony, and to Italian Somaliland, forming Italian East Africa. In 1941, British troops routed the Italians, and Haile Selassie returned to Addis Ababa. In 1952, Eritrea was incorporated into Ethiopia. On Sept. 12, 1974, Haile Selassie was deposed, the constitution suspended, and Ethiopia proclaimed a Socialist state under a collective military dictatorship called the Provisional Military Administrative Council (PMAC), also known as the Derg. U.S. aid stopped, and Cuban and Soviet aid began. Lt. Col. Mengistu Haile Mariam became head of state in 1977. During this period Ethiopia fought against Eritreans secessionists as well as Somali army. A group called the Ethiopian Peoples Revolutionary Democratic Front seized the capital in 1991, and in May a separatist guerrilla organization, the Eritrean Peoples Liberation Front, took control of the province of Eritrea. The two groups agreed that Eritrea would have an internationally supervised referendum on independence. This election took place in April 1993 with almost unanimous support for Eritrean independence. Ethiopia accepted and recognized Eritrea as an independent state within a few days. The different nationalities in Ethiopia and how they can co-exist without a conflict was always the issue. The question of nationalities in Ethiopia has been the most contentious issue since Ethiopia took its current shape between the late 1880s and the early 1900s. The northern part of the present day Ethiopia, inhabited by the majority Abyssinians and the minority Kushitic Agews existed for over 2 Millennia in the name of the Abyssinian Kingdom with remarkable civilizations such as A xum, Lalibela and Gonder. However, Ethiopia as we know it today is the result of the internal expansion by King Minelik II of Shoa during the late 1880s until the early 1900s. The majority (70%) of the current Ethiopian population, which lives in the southern, western and eastern regions of the country became part of the present day Ethiopia only during this period of internal expansion. The majority Kushitic peoples such as Sidama, Oromo, Afar, Ogaden, etc and the Omotic peoples such as Wolayita, Gamo, Gofa, Dawuro, Konta, etc and the Nilotic peoples living in the border between Ethiopia and the Sudan all became part of the present day Ethiopia between the 1880s and early 1900s. Historical evidences suggest that the rivalry between the two colonial powers, Britain and France in the horn of Africa, during the Scramble (competition) for Africa, facilitated the rapid Abyssinian expansion towards the south, the east and the west during this period. The two colonial powers provided King Minelik II ample rifles and other war materials that other ethnic groups living in the interior lacked. Therefore the King was able to easily subdue these hitherto independent African Kushitic, Omotic and Nilotic states with in a relatively short period of time. Although these peoples were annexed over a century ago, due to lack of sustainable economic development and industrialization as well as limited urbanization, 85 % of them still live off subsistence agriculture in rural areas. The peoples of the South, the East and the West have therefore fully preserved their unique cultures, languages, histories and economic systems until today. Due to the failure of nation building arising primarily from failed economic development and successive dictatorial political systems, the country remained an amalgamation of nations and nationalities who constantly resented being part of a failed state. It is based on this reality that Ethiopians from the South, the East and the West often voice concerns about the issues of nations and nationalities in the past and current Ethiopian politics. This is often misunderstood by their Abyssinian compatriots who unwittingly or intentionally refuse to accept the diversity of the country. The new government (1991) declared the following declaration: Given the Ethiopias existing situation, the problem of nationalities can be resolved if each nationality is accorded full right to self-governance. This means that each nationality will have regional autonomy to decide on matters concerning its internal affairs. Within its environs, it has the right to determine the contents of its political, economic and social life, use its own language and elect its own leaders and administrators to head its internal organs (Leenco Latta 1999:201) Many Ethiopians argue that over mentioned declaration has never been implemented as it is and the current government continues to massacre all its opponents and civilians. 2.2. Historic enmity between Somalia and Ethiopia The historic enmity between the two countries dates back when Imam Ahmed Ibn Ibrahim better known as Ahmed Gurey/gragn who was ethnic Somali general who conquered Abyssinia (Ethiopia) in 16th century. By the summer at 1532 the Imams well armed troops had overrun almost all Ethiopia,s eastern and southern provinces, among them Dawaro, Bali, Hadeya, Ganz, waj, Fatager and Ifat. (Richard Pankhurst 2001:87) The Ethiopians were forced to ask for help from the Portuguese, who landed at the port of Massawa on February 10, 1541 in the reign of the emperor Gelawdewos . This force was led by Christopher da Gama, and included 400 musketeers and a number of artisans and other non-combatants. In response, Ahmad received 900 well-armed men from the Ottomans in Yemen to assist him. While the Portuguese expedition were victorious in most of their engagements with Ahmads forces, da Gama allowed himself to be trapped by Ahmad somewhere north of the Tekezà © River, where he was killed along with all but 140 of his troops. The survivors and Galawedos were able to join forces, and drawing on the Portuguese supplies, they attacked Ahmad on February 21, 1543 in the Battle of Wayna Daga , where their 9,000 troops managed to defeat the 15,000 soldiers under Ahmad. Ahmad was killed by a Portuguese musketeer, who was mortally wounded in avenging da Gamas death. That episode was described in the book The Ethiopians News of the coming of the Portuguese, and of their powerful military equipment, spread rapidly through northern Ethiopia. Many soldiers who sided with the Imam now abandoned him, and flocked to Lebna Dengels widow empress Sebla Wangel. Dom Christovao and his companions were able to cross the greater part of Tegray, and joined up with the Empress, and with Bahr Nagash Yeshaq, the ruler of the coastal province, without encountering any opposition. They then proceeded westwards to Dambeya, north of Lake Tana, where the confronted the Imam, who in April 1542 for first time in his career encountered an enemy well equipped with cannons. Wounded in battle he was obliged to retreat, but managed to send an urgent appeal to zebid, and promised, in return for renewed Turkish aid, to become a vassal of the Ottoman emperor, Suleiman II. The Turks responded by immediately providing him with ten fields-guns and 700 well-armed soldiers. Thus greatly strengthened he succeeded in defeating the Portugu ese in August, when Dom Christovao was captured and beheaded. (Richard Pankhurst 2001:92) In Ethiopia the damage which [Ahmad] Gragn did has never been forgotten, wrote Paul B. Henze. Every Christian highlander still hears tales of Gragn in his childhood. Haile Selassie referred to him in his memoirs 2.3. Ogaden history The Ogaden is contentious territory between Ethiopia and Somalia and it is inhabited by ethnic Somalis. The occupied/annexed Somali territory inside Ethiopia lies between Oromia (Ethiopian region inhibited by Ethnic Oromo) to the West, Afar land to the Northwest, the Republic of Djibouti to the north, and Kenya to the south and The Somali Republic to the east. Somali agro-pastorals people with a single language, culture, and socio-economic structure inhabit the Ogaden territory. As a fact in many other African countries, the European imperial powers demarcated borders between Somalia and Ethiopia and the border between Somalia and Kenya without taking the political and social divisions into consideration. Imperial partition scattered the Somali people, for example, among five sovereign states. Fellow Somalis were now to be found in British Somaliland, Italian Somaliland, French Somaliland, Ethiopia and Kenya. (Alex Thomson, 2000: 13) The Ogaden Somali people were free and independent until colonial powers from overseas came to Africa and started arming the Abyssinian chiefs in the north of present day Ethiopia. The Abyssinians using the arms and expertise provided by the colonialists captured Harar in 1884 and started raiding Ogaden Somali villages in that area, killing civilians. The Ogaden Somalis resisted vehemently the encroachment of the Abyssinian expansionists and succeeded in halting their advance. Even though the Abyssinian military campaign to conquer the rest of the Somali territory failed, the colonial powers recognized its claim over the Ogaden Somaliland and signed treaties with them. In 1935, Italy invaded Abyssinia (Todays Ethiopia) and captured it along with the Ogaden and the territories of other nations in the area. Then the British defeated Italy in the Horn of Africa in 1941, and it administered the Ogaden for eight years until it transferred the first part of the Ogaden (Jigjiga area) to Ethiopia (the Abyssinians) for the first time. The next parts were transferred in 1954 and 1956. Thus, Ethiopia gained the control over the Ogaden without the knowledge or consent of the Ogaden Somalis. From that time onward, successive Ethiopian regimes mercilessly suppressed the Ogaden people and whenever the liberation movements seriously weakened and threatened Ethiopian colonialism, a foreign power directly intervened to re-establish its colonial rule over the Ogaden. Ethiopia since the beginning of this century and up to now has been characterized by one nation using the powers of state to subjugate and exploit all the other nations within that artificial system. For almost one century, the Abyssinians are abusing the concept of sovereignty and statehood to deprive the rights of other people living under the rule of the artificial state of Ethiopia. The historical reality of the process that resulted in its creation also continued to influence the Ethiopian governments interaction with and perception by these peoples. Ethiopian Governments, past and present, are perceived as alien by these people.(Leenco Lata, 1999: 41) It is historically clear that those suppressed nations inside Ethiopia among them Somalis (Ogaden) have always been struggling to be independent from Ethiopia one day. Ethiopia is a state founded on colonial doctrine and bases its rule on the use of force and emergency measures for oppressing the majority of the people and exploiting them. Ethiopia claims that African borders inherited from colonialism should be left intact and it inherited the Ogaden territory from the colonial powers. At the same time, Ethiopia is boasting to be the only African state that was never colonized. This means that Ethiopia has been a participating partner with the colonial powers that divided Africa among themselves but has never relinquished its colonial possessions. To maintain such a colonial state, the rulers had to build a massive military machine and embark on forcefully maintaining one of the most vicious authoritarian rules in the third world. The resultant resistance from the people and the inevitable taxing of material and moral resources of the oppressing elite became Ethiopia Achilles hill and brought about the downfall of its successive regimes. The relentless resistance of the colonized nations and the consequential resource drainage brought down both the rules of Haille Sellassie and the military Junta of Mengistu. The war between Somalia and Ethiopia over Ogaden region in 1964 on the one hand publicized the conflict and brought that cause to the regional and international arenas (Mohamed Abdi, 2007:60) 2.4. Ogaden war 1977 1980 In 1960 northern Somalia got independence from Britain and joined with southern Somalia to form the new state of Somalia. Successive Somali governments objected to the demarcation of the 1,000-mile border with Ethiopia, which was drawn by colonial powers. In 1964, the two countries fought a war over the Ogaden region of eastern Ethiopia, which is home to mainly ethnic Somalis. In 1977 a big war again erupted between Ethiopia and Somalia over Ogaden Territory. By the beginning of the war, the Somali National Army (SNA) was only 35,000-men strong and was vastly outnumbered by the Ethiopian army. However, throughout the 1970s, Somalia was receiving large amounts of Soviet military aid. The SNA had three times the tank force of Ethiopia, as well as a larger air force. By the summer 0f 1977 the Somali victory on the ground was unquestionable, but at the same time the Ethiopian were making headway on the diplomatic front (Mohamed Abdi, 2007:89) 2.5. Soviet and Egyptian role In addition to previous Russian fund and arms support to Somalia, Egypt sent millions of dollars in arms to Somalia, established military training and sent experts to Somalia due to Egypts longstanding policy of securing the Nile River flow by destabilizing Ethiopia. Even as Somalia gained military strength, Ethiopia grew weaker. In September 1974, Emperor Haile Selassie had been overthrown by the Derg.The Derg military dictatorship that came to power in Ethiopia following the ousting of Haile Selassie I of Ethiopia. (The military council), marking a period of turmoil. The Derg quickly fell into internal conflict to determine who would have primacy. Meanwhile, various anti-Derg as well as separatist movements began throughout the country. The regional balance of power now favored Somalia. One of the separatist groups seeking to take advantage of the chaos was the pro-Somalia Western Somali Liberation Front Western Somali Liberation Front (WSLf). The Western Somali Liberation Front was a separatist rebel group fighting in eastern Ethiopia to create an independent state. It played a major role in the Ogaden War of 1977-78 assisting the invading Somali Army. (WSLF) operating in the Somali-inhabited Ogaden area, which by late 1975 had struck numerous government outposts. From 1976 to 1977, Somalia supplied arms and other aid to the WSLF. 2.6. Ethiopia and soviet relationship Mengistu Haile Mariam was the most prominent officer of the Derg, the military junta that governed Ethiopia from 1974 to 1987, and the President of the Peoples Democratic Republic of Ethiopia from 1987 to 1991 as head of state on 11 February, 1977. However, the country remained in chaos as the military attempted to suppress its civilian opponents. Despite the violence, the Soviet Union, which had been closely observing developments, came to believe that Ethiopia was developing into a genuine Marxist-Leninist state and that it was in Soviet interests to aid the new regime. They thus secretly approached Mengistu with offers of aid that he accepted. Ethiopia closed the U.S. military mission and the communications center in April 1977. In June 1977, Mengistu accused Somalia of infiltrating SNA soldiers into the Somali area to fight alongside the WSLF. Despite considerable evidence to the contrary, Barre insisted that no such thing was occurring, but that SNA volunteers were being allowed to help the WSLF. Somalia decided to make a decisive move and invaded the Ogaden in 13 July 1977. Jijiga is a city in eastern Ethiopia and the capital of the Somali Region of that country and locates in the Jijiga Zone approximately 80 km east of Harar and 60 km west of the border with the Republic of Somalia; this city has been inflicted heavy casualties on assaulting forces. The Ethiopian Air Force is the air arm of the Military of Ethiopia and is tasked with protecting the air space, providing support to the ground forces as well as assisting during national emergencies. Air superiority is the dominance in the air power of one sides air forces over the other sides during a military campaign. It is defined in the NATO Glossary as That degree of dominance in the air battle of one force over another that permits the conduct of operations by the former and its related land, sea, and air forces at a given time The USSR, finding itself supplying both sides of a war, attempted to mediate a ceasefire. When their efforts failed, the Soviets abandoned Somalia. All aid to Siad Barres regime was halted, while arms shipments to Ethiopia were increased. Plus Soviet advisors flooded into the country along with around 15,000 from Cuba. The greatest single victory of the SNA-WSLF was a second assault on Jijiga in mid-September, in which the demoralized Ethiopian troops withdrew from the town. The local defenders were no match for the assaulting Somalis and the Ethiopian military was forced to withdraw past the strategic strongpoint of the Marda Pass, halfway between Jijiga and Harar. By September Ethiopia was forced to admit that it controlled only about 10% of the Ogaden and that the Ethiopian defenders had been pushed back into the non-Somali areas of Harerge, Bale, and Sidamo Province However, the Somalis were unable to press their advantage because of the high level of attrition among its tank battalions, constant Ethiopian air attacks on their supply lines, and the onset of the rainy season, which made the dirt roads unusable. During that time, the Ethiopian government managed to raise a giant militia force in its 100,000s and integrated it into the regular fighting force. Also, since the Ethiopian army was a client of U.S weapons, hasty acclimatization to the new Warsaw-pact bloc weaponry took place. From October 1977 until January 1978, the SNA-WSLF forces attempted to capture Harar, where 40,000 Ethiopians backed by Soviet-supplied artillery. Artillery is a military Combat Arms which employs any apparatus, machine, an assortment of tools or instruments, a system or systems used as weapons for the discharge of large projectiles in combat as a major contribution of fire power within the overall military capability of an armed force And Armored fighting vehicle The Ethiopians had regrouped with 1500 Soviet advisors and 11,000 Cuban soldiers. Though it reached the city outskirts by November, the Somali force was too exhausted to take the city and was eventually forced to retreat outside and await an Ethiopian counterattack. The expected Ethiopian-Cuban attack occurred in early February. However, it was accompanied by a second attack that the Somalis were not expecting. A column of Ethiopian and Cuban troops crossed northeast into the highlands between Jijiga and the border with Somalia, bypassing the SNA-WSLF force defending the Marda Pass. The attackers were thus able to assault from two directions in a pincer action, allowing the re-capturing of Jijiga in only two days while killing 3,000 defenders. The Somali defense collapsed and every major Ethiopian town was recaptured in the following weeks. Recognizing that his position was untenable, Siad Barre ordered the SNA to retreat back into Somalia on 9 March 1978. The last significant Somali unit left Ethiopia on 15 March 1978, marking the end of the war. 3.0. Somali state collapse and shift of balance of power in horn of Africa Already in 1980s many rebels supported by Ethiopian government were aiming to oust the former president of Somalia Mohamed said Barre. By the end of the 1980s, armed opposition to Barres government, fully operational in the northern regions, had spread to the central and southern regions. Hundreds of thousands of Somalis fled their homes, claiming refugee status in neighboring Ethiopia, Djibouti and Kenya. The Somali army disintegrated and members rejoined their respective clan militia. Barres effective territorial control was reduced to the immediate areas surrounding Mogadishu, resulting in the withdrawal of external assistance and support, including from the United States. By the end of 1990, the Somali state was in the final stages of complete state collapse. In the first week of December 1990, Barre declared a state of emergency as USC forces advanced toward Mogadishu. In January 1991, armed opposition factions removed Barre out of power, resulting in the complete collapse of th e central government. State collapse in Somalia had become a fact of life in the region. Ethiopia and Somalia both saw the end of dictatorial rule in 1991. But whereas Ethiopia had picked itself up and reconfigured its political landscape, Somalias clan based political dynamics had consistently worked against the re-establishment of a central government. Somalia was fragmented, but by the late 1990s some of its fragments, Notably Somaliland and Punt land in the northwest and northeast of the country respectively, had established their own administrations that fulfilled most of the functions of government As one can imagine the losses and repercussions of the civil war was almost irretrievable. The human cost was terrible. Thousands of civilians were killed and wounded, and at least half a million fled their homes seeking across the border in Ethiopia and in the republic of Djibouti. Thousands of refugees eventually found refuge in Canada, Britain, Scandinavia, Italy and the USA (Ioan Lewis, 2008:71). 3.1. The rise of warlords and the rise of ICU and Ethiopian intervention with economical support from USA With the collapse of the state in January 1991, Somalia became the first country in modern history to become stateless. Consequently, lawlessness became rampant in the country and criminal militias and gangs terrorized the population. A little over a year after the Somali state collapsed, violent confrontations developed between two competing factions in Mogadishu which finally led to one of them using food as a weapon against vulnerable population in southwestern region of the country in Baidoa. Farmers in the region were unable to cultivate their fields due to the fear caused by gangs and with warlords blocking food shipments to the region thousands of people began to slowly waste away. By the time the news media took note of the problem an awful famine was in full swing and tens of thousands of people were deliberately condemned to death through starvation. The United Nations which had a small contingent of peace-keepers was unable to clear bandits off the roads in order to delive r food aid to those who need it. Life conditions became so bad that the first President Bush was moved to act and ordered thousands of American troops to enter Somalia in order to open the roads so emergency food aid can urgently get through to the people. The troops were able to accomplish this task with relative ease and as a result tens of thousands of lives were saved. By contrast, rebuilding Somalias government from scratch was more difficult, even under the best of circumstances, but the US/UN force had ill-defined mandate and got bad advice regarding the causes of Somalias disintegration. American/UN agenda of rebuilding the government was incoherent and led to a failure in which 18 American soldiers were killed by the militias of one of the warlords of Mogadishu. By then a new American President, Clinton, was so shaken by this singular event that he decided to evacuate US forces from Somalia. Other nations who had contributed troops to the campaign and the UN followed and So malia was left to the warlords. The terror of Warlords became the order of the day since 1995 and several attempts to form a national government failed. A most promising effort in this regard was in the neighboring state of Djibouti where representatives of nearly all Somali civil society groups were invited in 1999 excluding warlords. The conference successfully led to the establishment of a Transitional National Government (TNG). However, the Ethiopian government which had supported many of the warlords, particularly Mr. Abdullahi Yusuf, and supplied them with weapons over the years was not happy about the prospect of a civic administration and worked against it from the start. The combination of Ethiopian sabotage and Somali leaders incompetence destroyed this precious chance. At one point the Ethiopian Foreign Minister told the TNGs Foreign Affair chief that Ethiopia will be able to support the Somali government on the condition that their ally, Mr. Yusuf, was appointed as prime minister. The Ethiopian minister was not pleased when he was told that the responsibility to appoint and confirm the PM rested with the president and parliament. In the meantime, Ethiopia used its diplomatic influence in Africa and elsewhere to call for yet another Somali reconciliation conference with the pretext of forming an inclusive government while it continued to supply the warlords with weapons. The proposal was accepted by the Intergovernmental Agency on development (IGAD) and there started another reconciliation process in which the mediators (Kenya and Ethiopia) openly favored and supported the warlords. After two years of negotiations the conference was brought to a conclusion without any reconciliation among Somalis. The Ethiopian government successfully attained its goals of wasting the remaining time of the TNGs tenure, enabled the warlords to appoint more than two-thirds of the members of parliament, and finally succeeded in having its clients selected as president and prime minister. American policy, during the long two years of negotiations in Kenya, was characterized by tacit support for warlords domination of the conference. In the main, the US representatives in Kenya watched the process from the sidelines and seemed they did not like the quality of the output in the form of the Transitional Federal Government (TFG). For nearly two years after the formation of the TFG the American government remained disinterested in the affairs of the TFG. Instead it financed the formation of so called anti-terror alliance which consisted of the very warlords who have killed the population for over a decade. Americas objective in supporting the warlords was to find and arrest three people accused of being involved in the attacks on US embassies in Kenya and Tanzania in 1998 and who were presumed to be hiding somewhere in southern Somalia. The warlords contract with the CIA also included capturing or killing those who were considered radical Islamists. Americas warlord projec t backfired as the majority of Mogadishus population sided with the Muslim leaders and rooted the warlords out. American policy makers panicked with the formation of the Union of Islamic Courts (UICs) and the liberation of Mogadishu and surrounding region from the tyranny of the warlords. Shortly after UICs took over Mogadishu senior American policy makers began to speak about the internationally legitimate government of Somalia and actively used Americas diplomatic and other resources to bestow respect on what it previously considered week operation. Meanwhile, Ethiopia activated its propaganda machine and accused the courts of trying to establish a fundamentalist regime which it claimed will endanger its security despite the fact that Somalia did not have an army. It immediately gave a protection force for its client Somali government holed in the regional center of Baidoa. As the Courts spread their reach into most parts of southern Somalia, Ethiopia increased its troop presence in Baidoa into several thousand heavily armed units. The US government encouraged this invasion and used its diplomatic muscle to shield Ethiopia from international criticism. The united American-Ethiopian propaganda machine completed the demonization of the courts as a fundamentalist organization in cahoots with Al Qaida. This joint effort led to US government sponsoring a resolution at the Security Council, 1725, which mandated the deployment of an African Union force in Somalia aimed at protecting the TFG and stabilizing the country. Other countries in the Security Council insisted and prevailed that those countries who share
Tuesday, September 3, 2019
Carol Tavris In Groups We Shrink From Loner’s Heroics :: Sociology Groups Shring Tavris Essays
Carol Tavris' In Groups We Shrink From Loner’s Heroics â€Å"In Groups We Shrink From Loner’s Heroics†is an essay about how people in groups behave together. The author of this essay believes that when people are in groups they will do nothing to help a person in distress and that they cannot think for themselves. â€Å"In Groups We Shrink From Loner’s Heroics†, by Carol Tavris was ineffective because it used logical fallacies, overused pathos, had weak references to logos, and used inductive arguments. The author of the essay, Carol Tavris, seems to be very passionate about what she is writing. She has her doctorate in Psychology and has had her articles published in many well-known magazines. The intended audience of her essay is the general public. The purpose of this article is to inform the public that they need to stand out and use their own minds in a group setting instead of hiding in the comfort of their fellow friends and colleagues. The essay is written to be very informal. It uses a lot of connotative language as well as a subjective point of view. The author tries to use facts to support her way of thinking, and also uses some examples and descriptions. The largest downfall to the article is her use of inductive arguments. The author uses true stories and a few case studies, at the beginning of the essay, to show how some people have acted when they are with a group of people. But, the rest of her argument is based on these few studies. She tries to argue that all groups behave as these few examples, in the essay, did. These few, rare occurrences cannot be the basis for an entire argument about how groups behave. They paint too broad of a picture. The author mainly appeales to pathos. She tells a story of a woman being stabbed while her neighbors look on and also, of a man, named Rodney King, who was beaten by a few police offices while ten other officers looked on. These are good examples for her argument but, she uses these infrequent instances to try and sway her audience into thinking that they are common occurrences.
Prescription narcotics Essay -- essays research papers
The Need for Restrictions â€Å"Why there should be stricter regulations on the availability of prescription narcotics†Despite efforts to decrease the number of deaths and overdoses related to narcotic medications, such as OxyContin, and minimize the number of people illegally obtaining them, the measures that the DEA (Drug Enforcement Administration) in specific are taking are not enough. The literal definition of a narcotic is a drug that produces numbness or stupor; often taken for pleasure or to reduce pain; extensive use can lead to addiction. Narcotics are normally prescription medications that are given to patients to help ease the constant pain cause by cancer or other long term illnesses. â€Å"When one in 10 high school senior’s reports abusing prescription painkillers, the DEA is obligated to protect our children and the public safety†says Karen P. Tandy administrator of the DEA(1). Tandy is saying that when the abuse of prescription pain medication is taking over that many students the DEA must step in for the sake of future generations. There is a long process that not many average Americans know about that all pharmaceutical products, especially addictive medications have to go through before they reach home medicine cabinets. This process is called â€Å"Diversion†. It is an important chain like process that the DEA (Drug Enforcement Administration) have been using for years to look at where highly addictive drugs, like OxyContin, go and who they come into contact with. From the pharmaceutical company that literally make the product, to the drug wholesalers that sell the product, and then into the hands of doctors and pharmacies who prescri be and distribute the medications. The purpose of diversion is to take the information and look for certain situations where drugs were lost, stolen, or illegally distributed and give proper punishment to those people. The problem of abusing prescription narcotics became noticeably out of control in the 1990’s. The problem lies in the fact that it is 2005 and the numbers of overdoses and deaths have been and are still rising at astonishing rates. An argument however, that many people have about advancing restrictions on OxyContin and other schedule 2 narcotics is that the needed process that one might have to go through in order to properly obtain the drug would be an ‘invasion of privacy.†Some believe that reportin... ...rs†¦the number of patients in motor vehicle crashes who are ‘methadone impaired,’†says John H. Burton, MD Medical Director for Maine Emergency Medical Services.(3) To think that the problem of abusing any kind of drug would just disappear with one solution is naive and absurdly optimistic. However, to think that all the DEA is doing right now to prevent harmfully addictive and destructive medications is enough is plain ignorant. The DEA has made substantial progress toward making OxyContin and other prescribed narcotics less available for abusers. But first hand accounts and shocking statistics prove that these measures are clearly not enough. It is true and will always be true that free will is a legitimate part of this equation. The abuse of any kind of drug is almost guaranteed to be present at all times no matter how hard the government tries. If a person wants it they will have it. The fact also remains that people with addictions cannot control themselves or their addictions, that’s why it is called an addiction. Therefore making it the partial obligation of the DEA and the government to not only recognize this desperate need for r estrictions but do something more about it.
Monday, September 2, 2019
P’s Pert Plus: a Pan- European Brand?
Q1. How attractive is the Pan- European market for pert plus in terms of demand potential? Competition? Pan- European market is quite attractive for pert plus  in terms of demand as the consumers test results showed that the product concept of ‘wash & go' their (time-saving benefits) 28% consumers said that they would definalty buy the product that was only 1 percent less then already established bran there Vidal Sasson. Also because they are gradually accepting the idea of 2-in-1 shampoo more and thus it would be beneficial to launch in European market. P&G's competitors there are Unilever, Colgate and Lo ‘Oreal. P&Gs own competitor brands are heavily advertised there by European standards. Therefore launch of the product need to illustrate quality and time- saving benefits and also need to educate the market in the use of conditioners further. Q2. What competitive advantages does Pert Plus have? Disadvantages? Competitive advantage for pert plus is the benefits of time-saving and convenient everyday use of the product. Thos benefit is very essential and thus required right positioning. Inadequate availability of production capacity was a disadvantage for pert plus. Also lead times for alternative pack sizes and designs (250ml preferred size) were also a restriction for them as it would take six months lead time. Q3. Which countries would be the leading markets in Europe? What are the advantages and disadvantages of entering a leading market first? The countries that could be leading markets are Great Britain as it has a high market size for usage of conditioners and shampoos, especially conditioners that is the highest rate among the other 4 countries given. Therefore they would not have to educate them much about the usage of conditioners but can face tough competition. West Germany has highest rate of value of shampoos and 2nd highest in conditioners (Exhibit 1). Therefore has the potential of being a leading market but would require an innovative marketing campaign and emphasis on pert plus's competitive advantages. Entering a leading market first has both advantages and disadvantages. Market segmentation is usually a must as competition is intense. New entrant will have to use niche strategies, positioning their product not in the core of the market but in specialty area. As the product is new it has the chance to develop a new market and gain favorable first mover advantages, something that takes resources, focus and continuous monitoring of penetration. Q4. What does marketing research tell about the price and positioning decision for Europe? Brand choice? Should the BC-18 technology be introduced with a pan-European name, or with local brand names, or even with a mixture of both approaches? Price and packaging alternatives were tested on only two brands: one brand from the lower-price segment and another brand that had a high quality product concept that is product concepts where possible price sensitivity would be easily detected. According to the market research the consumer were willing to pay the equal price for the selected product (Vidal Sassoon, Shamtu, Pantene, Pert Plus). The new technology â€Å"2-in-1†for shampoo and conditioner in one wash, its positioning was same as Vidal Sassoon Shampoo â€Å"for great-looking hair in a convenient way†. The brand choice would be highly not so easy because all the brands are providing the same technology 2-in-1 formula. The BC-18 technology would be introduced with a mixture of both approaches, because P was the first packaged goods companies to go to pan-European. The American company had established a pan-European focus in its R-effort and a system of â€Å"lead countries†for pan-European product roll-outs. And plus with a local brand name customer would easily recognized the brand globally.
Sunday, September 1, 2019
Ansys Tutorial Release 12.1
 ® ANSYS Tutorial Release 12. 1 Structural & Thermal Analysis Using the ANSYS Release 12. 1 Environment Kent L. Lawrence Mechanical and Aerospace Engineering University of Texas at Arlington SDC PUBLICATIONS www. SDCpublications. com Schroff Development Corporation Visit the following websites to learn more about this book: ANSYS Tutorial 2-1 Lesson 2 Plane Stress Plane Strain 2-1 OVERVIEW Plane stress and plane strain problems are an important subclass of general threedimensional problems. The tutorials in this lesson demonstrate:  ¦Solving planar stress concentration problems. Evaluating potential inaccuracies in the solutions.  ¦Using the various ANSYS 2D element formulations. 2-2 INTRODUCTION It is possible for an object such as the one on the cover of this book to have six components of stress when subjected to arbitrary three-dimensional loadings. When referenced to a Cartesian coordinate system these components of stress are: Normal Stresses ?x, ? y, ? z Shear Stresses ? xy, ? yz, ? zx Figure 2-1 Stresses in 3 dimensions. In general, the analysis of such objects requires three-dimensional modeling as discussed in Lesson 4.However, two-dimensional models are often easier to develop, easier to solve and can be employed in many situations if they can accurately represent the behavior of the object under loading. 2-2 ANSYS Tutorial A state of Plane Stress exists in a thin object loaded in the plane of its largest dimensions. Let the X-Y plane be the plane of analysis. The non-zero stresses ? x, ? y, and ? xy lie in the X – Y plane and do not vary in the Z direction. Further, the other stresses (? z,? yz , and ? zx ) are all zero for this kind of geometry and loading.A thin beam loaded in its plane and a spur gear tooth are good examples of plane stress problems. ANSYS provides a 6-node planar triangular element along with 4-node and 8-node quadrilateral elements for use in the development of plane stress models. We will use both triangles and qua ds in solution of the example problems that follow. 2-3 PLATE WITH CENTRAL HOLE To start off, let’s solve a problem with a known solution so that we can check our computed results as well as our understanding of the FEM process. The problem is that of a tensile-loaded thin plate with a central hole as shown in Figure 2-2.Figure 2-2 Plate with central hole. The 1. 0 m x 0. 4 m plate has a thickness of 0. 01 m, and a central hole 0. 2 m in diameter. It is made of steel with material properties; elastic modulus, E = 2. 07 x 1011 N/m2 and Poisson’s ratio, ? = 0. 29. We apply a horizontal tensile loading in the form of a pressure p = -1. 0 N/m2 along the vertical edges of the plate. Because holes are necessary for fasteners such as bolts, rivets, etc, the need to know stresses and deformations near them occurs very often and has received a great deal of study.The results of these studies are widely published, and we can look up the stress concentration factor for the case s hown above. Before the advent of suitable computation methods, the effect of most complex stress concentration geometries had to be evaluated experimentally, and many available charts were developed from experimental results. The uniform, homogeneous plate above is symmetric about horizontal axes in both geometry and loading. This means that the state of stress and deformation below a Plane Stress / Plane Strain 2-3 orizontal centerline is a mirror image of that above the centerline, and likewise for a vertical centerline. We can take advantage of the symmetry and, by applying the correct boundary conditions, use only a quarter of the plate for the finite element model. For small problems using symmetry may not be too important; for large problems it can save modeling and solution efforts by eliminating one-half or a quarter or more of the work. Place the origin of X-Y coordinates at the center of the hole. If we pull on both ends of the plate, points on the centerlines will move al ong the centerlines but not perpendicular to them.This indicates the appropriate displacement conditions to use as shown below. Figure 2-3 Quadrant used for analysis. In Tutorial 2A we will use ANSYS to determine the maximum horizontal stress in the plate and compare the computed results with the maximum value that can be calculated using tabulated values for stress concentration factors. Interactive commands will be used to formulate and solve the problem. 2-4 TUTORIAL 2A – PLATE Objective: Find the maximum axial stress in the plate with a central hole and compare your result with a computation using published stress concentration factor data.PREPROCESSING 1. Start ANSYS, select the Working Directory where you will store the files associated with this problem. Also set the Jobname to Tutorial2A or something memorable and provide a Title. (If you want to make changes in the Jobname, working Directory, or Title after you’ve started ANSYS, use File > Change Jobname or Di rectory or Title. ) Select the six node triangular element to use for the solution of this problem. 2-4 ANSYS Tutorial Figure 2-4 Six-node triangle. The six-node triangle is a sub-element of the eight-node quadrilateral. 2.Main Menu > Preprocessor > Element Type > Add/Edit/Delete > Add > Structural Solid > Quad 8node 183 > OK Figure 2-5 Element selection. Select the triangle option and the option to define the plate thickness, otherwise a unit thickness is used. 3. Options (Element shape K1) > Triangle, Options (Element behavior K3) > Plane strs w/thk > OK > Close Plane Stress / Plane Strain 2-5 Figure 2-6 Element options. 4. Main Menu > Preprocessor > Real Constants > Add/Edit/Delete > Add > OK Figure 2-7 Real constants. Enter the plate thickness of 0. 01 m. ) >Enter 0. 01 > OK > Close Figure 2-8 Enter the plate thickness. 2-6 ANSYS Tutorial Enter the material properties. 5. Main Menu > Preprocessor > Material Props > Material Models Material Model Number 1, click Structural > Line ar > Elastic > Isotropic Enter EX = 2. 07E11 and PRXY = 0. 29 > OK (Close the Define Material Model Behavior window. ) Create the geometry for the upper right quadrant of the plate by subtracting a 0. 2 m diameter circle from a 0. 5 x 0. 2 m rectangle. Generate the rectangle first. . Main Menu > Preprocessor > Modeling > Create > Areas > Rectangle > By 2 Corners Enter (lower left corner) WP X = 0. 0, WP Y = 0. 0 and Width = 0. 5, Height = 0. 2 > OK 7. Main Menu > Preprocessor > Modeling > Create > Areas > Circle > Solid Circle Enter WP X = 0. 0, WP Y = 0. 0 and Radius = 0. 1 > OK Figure 2-9 Create areas. Plane Stress / Plane Strain 2-7 Figure 2-10 Rectangle and circle. Now subtract the circle from the rectangle. (Read the messages in the window at the bottom of the screen as necessary. ) 8.Main Menu > Preprocessor > Modeling > Operate > Booleans > Subtract > Areas > Pick the rectangle > OK, then pick the circle > OK (Use Raise Hidden and Reset Picking as necessary. ) Figure 2-11 Geo metry for quadrant of plate. Create a mesh of triangular elements over the quadrant area. 9. Main Menu > Preprocessor > Meshing > Mesh > Areas > Free Pick the quadrant > OK Figure 2-12 Triangular element mesh. Apply the displacement boundary conditions and loads to the geometry (lines) instead of the nodes as we did in the previous lesson.These conditions will be applied to the FEM model when the solution is performed. 10. Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Displacement > On Lines Pick the left edge of the quadrant > OK > UX = 0. > OK 2-8 ANSYS Tutorial 11. Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Displacement > On Lines Pick the bottom edge of the quadrant > OK > UY = 0. > OK Apply the loading. 12. Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Pressure > On Lines.Pick the right edge of the quadrant > OK > Pressure = -1. 0 > OK (A positive pressure would be a compressive load, so we use a nega tive pressure. The pressure is shown by the two arrows. ) Figure 2-13 Model with loading and displacement boundary conditions. The model-building step is now complete, and we can proceed to the solution. First, to be safe, save the model. 13. Utility Menu > File > Save as Jobname. db (Or Save as †¦. ; use a new name) SOLUTION The interactive solution proceeds as illustrated in the tutorials of Lesson 1. 14. Main Menu > Solution > Solve > Current LS > OKThe /STATUS Command window displays the problem parameters and the Solve Current Load Step window is shown. Check the solution options in the /STATUS window and if all is OK, select File > Close In the Solve Current Load Step window, select OK, and when the solution is complete, Close the ‘Solution is Done! ’ window. POSTPROCESSING We can now plot the results of this analysis and also list the computed values. First examine the deformed shape. 15. Main Menu > General Postproc > Plot Results > Deformed Shape > Def. + Undef. > OK Plane Stress / Plane Strain 2-9 Figure 2-14 Plot of Deformed shape.The deformed shape looks correct. (The undeformed shape is indicated by the dashed lines. ) The right end moves to the right in response to the tensile load in the X direction, the circular hole ovals out, and the top moves down because of Poisson’s effect. Note that the element edges on the circular arc are represented by straight lines. This is an artifact of the plotting routine not the analysis. The six-node triangle has curved sides, and if you pick on a mid-side of one these elements, you will see that a node is placed on the curved edge. The maximum displacement is shown on the graph legend as 0. 2e-11 which seems reasonable. The units of displacement are meters because we employed meters and N/m2 in the problem formulation. Now plot the stress in the X direction. 16. Main Menu > General Postproc > Plot Results > Contour Plot > Element Solu > Stress > X-Component of stress > OK Use PlotCtrls > Symbols [/PSF] Surface Load Symbols (set to Pressures) and Show pre and convect as (set to Arrows) to display the pressure loads. Figure 2-15 Surface load symbols. Also select Display All Applied BCs 2-10 ANSYS Tutorial Figure 2-16 Element SX stresses.The minimum, SMN, and maximum, SMX, stresses as well as the color bar legend give an overall evaluation of the ? x (SX) stress state. We are interested in the maximum stress at the hole. Use the Zoom to focus on the area with highest stress. (Your meshes and results may differ a bit from those shown here. ) Figure 2-17 SX stress detail. Plane Stress / Plane Strain 2-11 Stress variations in the actual isotropic, homogeneous plate should be smooth and continuous across elements. The discontinuities in the SX stress contours above indicate that the number of elements used in this model is oo few to calculate with complete accuracy the stress values near the hole because of the stress gradients there. We will not accept this stress solu tion. More six-node elements are needed in the region near the hole to find accurate values of the stress. On the other hand, in the right half of the model, away from the stress riser, the calculated stress contours are smooth, and SX would seem to be accurately determined there. It is important to note that in the plotting we selected Element Solu (Element Solution) in order to look for stress contour discontinuities.If you pick Nodal Solu to plot instead, for problems like the one in this tutorial, the stress values will be averaged before plotting, and any contour discontinuities (and thus errors) will be hidden. If you plot nodal solution stresses you will always see smooth contours. A word about element accuracy: The FEM implementation of the truss element is taken directly from solid mechanics studies, and there is no approximation in the solutions for node-loaded truss structures formulated and solved in the ways discussed in Lesson 1.The continuum elements such as the ones for plane stress and plane strain, on the other hand, are normally developed using displacement functions of a polynomial type to represent the displacements within the element, and the higher the polynomial, the greater the accuracy. The ANSYS six-node triangle uses a quadratic polynomial and is capable of representing linear stress and strain variations within an element. Near stress concentrations the stress gradients vary quite sharply. To capture this variation, the number of elements near the stress concentrations must be increased proportionately.To obtain more elements in the model, return to the Preprocessor and refine the mesh, first remove the pressure. All elements are subdivided and the mesh below is created 17. Main Menu > Preprocessor > Loads > Define Loads > Delete > Structural > Pressure > On Lines. Pick the right edge of the quadrant. Main Menu > Preprocessor > Meshing > Modify Mesh > Refine At > All (Select Level of refinement 1. ) Figure 2-18 Global mesh refineme nt. 2-12 ANSYS Tutorial We will also refine the mesh selectively near the hole. 18.Main Menu > Preprocessor > Meshing > Modify Mesh > Refine At > Nodes. (Select the three nodes shown. ) > OK (Select the Level of refinement = 1) > OK Figure 2-19 Selective refinement at nodes. (Note: Alternatively you can use Preprocessor > Meshing > Clear > Areas to remove all elements and build a completely new mesh. Plot > Areas afterwards to view the area again. Note also that too much local refinement can create a mesh with too rapid a transition between fine and coarse mesh regions. ) Reapply the pressure loading, repeat the solution, and replot the stress SX. 9. Main Menu > Solution > Solve > Current LS > OK Save your work. 20. File > Save as Jobname. db Plot the stresses in the X direction. 21. Main Menu > General Postproc > Plot Results > Contour Plot > Element Solu > Stress > X-Component of stress > OK Plane Stress / Plane Strain 2-13 Figure 2-20 SX stress contour after mesh refinement. Figu re 2-21 SX stress detail contour after mesh refinement. The element solution stress contours are now smooth across element boundaries, and the stress legend shows a maximum value of 4. 386 Pa, a 4. percent change in the SX stress computed using the previous mesh. To check this result, find the stress concentration factor for this problem in a text or reference book or from a suitable web site. For the geometry of this example we find Kt = 2. 17. We can compute the maximum stress using (Kt)(load)/(net cross sectional area). Using the pressure p = 1. 0 Pa we obtain. ? x MAX = 2. 17 * p * (0. 4)(0. 01) /[(0. 4 ? 0. 2) * 0. 01] = 4. 34 Pa 2-14 ANSYS Tutorial The computed maximum value is 4. 39 Pa which is around one percent in error, assuming that the value of Kt is exact. -5 THE APPROXIMATE NATURE OF FEM As mentioned above, the stiffness matrix for the truss elements of Lesson 1 can be developed directly and simply from elementary solid mechanics principles. For continuum problems in t wo and three-dimensional stress, this is generally no longer possible, and the element stiffness matrices are usually developed by assuming something specific about the characteristics of the displacements that can occur within an element. Ordinarily this is done by specifying the highest degree of the polynomial that governs the displacement distribution within an element.For h-method elements, the polynomial degree depends upon the number of nodes used to describe the element, and the interpolation functions that relate displacements within the element to the displacements at the nodes are called shape functions. In ANSYS, 2-dimensional problems can be modeled with six-node triangles, four-node quadrilaterals or eight-node quadrilaterals. Figure 2-22 Triangular and quadrilateral elements. The greater the number of nodes, the higher the order of the polynomial and the greater the accuracy in describing displacements, stresses and strains within the element. If the stress is constan t throughout a region, a very imple model is sufficient to describe the stress state, perhaps only one or two elements. If there are gradients in the stress distributions within a region, high-degree displacement polynomials and/or many elements are required to accurately analyze the situation. These comments explain the variation in the accuracy of the results as different numbers of elements were used to solve the problem in the previous tutorial and why the engineer must carefully prepare a model, start with small models, grow the models as understanding of the problem develops and carefully interpret the calculated results.The ease with which models can be prepared and solved sometimes leads to careless evaluation of the computed results. Plane Stress / Plane Strain 2-15 2-6 ANSYS FILES The files created during the solution were saved in step 20 of Tutorial 2A. Look in the working directory and you see Tutorial2A files with extensions BCS, db, dbb, esav, full, mntr, rst, and sta t. However, the Tutorial 2A problem can be reloaded using only Tutorial2A. db, so if you want to save disk space, you can delete the others. 2-7 ANSYS GEOMETRY The finite element model consists of elements and nodes and is separate from the geometry on which it may be based.It is possible to build the finite element model without consideration of any underlying geometry as was done in the truss examples of Lesson 1, but in many cases, development of the geometry is the first task. Two-dimensional geometry in ANSYS is built from keypoints, lines (straight, arcs, splines), and areas. These geometric items are assigned numbers and can be listed, numbered, manipulated, and plotted. The keypoints (2,3,4,5,6), lines (2,3,5,9,10), and area (3) for Tutorial 2A are shown below. (Your numbering may differ. ) Figure 2-23 Keypoints, lines and areas.The finite element model developed previously for this part used the area A3 for development of the node/element FEM mesh. The loads, displacement b oundary conditions and pressures were applied to the geometry lines. When the solution step was executed, the loads were transferred from the lines to the FEM model nodes. Applying boundary conditions and loads to the geometry facilitates remeshing the problem. The geometry does not change, only the number and location of nodes and elements, and at solution time, the loads are transferred to the new mesh.Geometry can be created in ANSYS interactively (as was done in the previous tutorial) or it can be created by reading a text file. For example, the geometry of Tutorial 2A can be generated with the following text file using the File > Read Input from command sequence. (The keypoint, line, etc. numbers will be different from those shown above. ) 2-16 ANSYS Tutorial /FILNAM,Geom /title, Stress Concentration Geometry ! Example of creating geometry using keypoints, lines, arcs /prep7 ! Create geometry k, 1, 0. 0, 0. 0 ! Keypoint 1 is at 0. 0, 0. 0 k, 2, 0. 1, 0. 0 , 3, 0. 5, 0. 0 k, 4, 0. 5, 0. 2 k, 5, 0. 0, 0. 2 k, 6, 0. 0, 0. 1 L, L, L, L, 2, 3, 4, 5, 3 4 5 6 ! Line from keypoints 2 to 3 ! arc from keypoint 2 to 6, center kp 1, radius 0. 1 LARC, 2, 6, 1, 0. 1 AL, 1, 2, 3, 4, 5 ! Area defined by lines 1,2,3,4,5 Geometry for FEM analysis also can be created with solid modeling CAD or other software and imported into ANSYS. The IGES (Initial Graphics Exchange Specification) neutral file is a common format used to exchange geometry between computer programs. Tutorial 2B demonstrates this option for ANSYS geometry development. -8 TUTORIAL 2B – SEATBELT COMPONENT Objective: Determine the stresses and deformation of the prototype seatbelt component shown in the figure below if it is subjected to tensile load of 1000 lbf. Figure 2-24 Seatbelt component. The seatbelt component is made of steel, has an over all length of about 2. 5 inches and is 3/32 = 0. 09375 inches thick. A solid model of the part was developed in a CAD system and exported as an IGES file. The f ile is imported into ANSYS for analysis. For simplicity we will analyze only the right, or ‘tongue’ portion of the part in this tutorial.Plane Stress / Plane Strain 2-17 Figure 2-25 Seatbelt ‘tongue’. PREPROCESSING 1. Start ANSYS, Run Interactive, set jobname, and working directory. Create the top half of the geometry above. The latch retention slot is 0. 375 x 0. 8125 inches and is located 0. 375 inch from the right edge. If you are not using an IGES file to define the geometry for this exercise, you can create the geometry directly in ANSYS with key points, lines, and arcs by selecting File > Read Input from to read in the text file given below and by skipping the IGES import steps 2, 3, 4, and 10 below. FILNAM,Seatbelt /title, Seatbelt Geometry ! Example of creating geometry using keypoints, lines, arcs /prep7 ! Create geometry k, 1, 0. 0, 0. 0 ! Keypoint 1 is at 0. 0, 0. 0 k, 2, 0. 75, 0. 0 k, 3, 1. 125, 0. 0 k, 4, 1. 5, 0. 0 k, 5, 1. 5, 0. 5 k, 6, 1. 2 5, 0. 75 k, 7, 0. 0, 0. 75 k, 8, 1. 125, 0. 375 k, 9, 1. 09375, 0. 40625 k, 10, 0. 8125, 0. 40625 k, 11, 0. 75, 0. 34375 k, 12, 1. 25, 0. 5 k, 13, 1. 09375, 0. 375 k, 14, 0. 8125, 0. 34375 2-18 L, L, L, L, L, L, L, L, ANSYS Tutorial 1, 2 3, 4 4, 5 6, 7 7, 1 3, 8 9, 10 11, 2 ! arc LARC, LARC, LARC, Line from keypoints 1 to 2 from keypoint 5 to 6, center kp 12, radius 0. 25, etc. 5,6, 12, 0. 25 8, 9, 13, 0. 03125 10, 11, 14, 0. 0625 AL,all ! Use all lines to create the area. 2. Alternatively, use a solid modeler to create the top half of the component shown above in the X-Y plane and export an IGES file of the part. To import the IGES file 3. Utility Menu > File > Import > IGES Select the IGES file you created earlier. Accept the ANSYS import default settings. If you have trouble with the import, select the alternate options and try again.Defeaturing is an automatic process to remove inconsistencies that may exist in the IGES file, for example lines that, because of the modeling or th e file translation process, do not quite join to digital precision accuracy. Figure 2-26 IGES import. Turn the IGES solid model around if necessary so you can easily select the X-Y plane. Plane Stress / Plane Strain 2-19 4. Utility Menu > PlotCtrls > Pan, Zoom, Rotate > Back, or use the side-bar icon. Figure 2-27 Seatbelt solid, front and back. 5.Main Menu > Preprocessor > Element Type > Add/Edit/Delete > Add > Solid > Quad 8node 183 > OK (Use the 8-node quadrilateral element for this problem. ) 6. Options > Plane strs w/thk > OK > Close Enter the thickness 7. Main Menu > Preprocessor > Real Constants > Add/Edit/Delete > Add > (Type 1 Plane 183) > OK > Enter 0. 09375 > OK > Close Enter the material properties 8. Main Menu > Preprocessor > Material Props > Material Models Material Model Number 1, click Structural > Linear > Elastic > Isotropic Enter EX = 3. 0E7 and PRXY = 0. > OK (Close Define Material Model Behavior window. ) Now mesh the X-Y plane area. (Turn on area numbers if it helps. ) 9. Main Menu > Preprocessor > Meshing > Mesh > Areas > Free. Pick the X-Y planar area > OK IMPORTANT NOTE: The mesh below was developed from an IGES geometry file. Using the text file geometry definition, may produce a much different mesh. If so, use the Modify Mesh refinement tools to obtain a mesh density that produces results with accuracies comparable to those given below. Computed stress values can be surprisingly sensitive to mesh differences. -20 ANSYS Tutorial Figure 2-28 Quad 8 mesh. The IGES solid model is no longer needed, and since its lines and areas may interfere with subsequent modeling operations, we can delete it from the session. 10. Main Menu > Preprocessor > Modeling > Delete > Volume and Below (Don’t be surprised if everything disappears. Just Plot > Elements to see the mesh again. ) 11. Utility Menu > PlotCtrls > Pan, Zoom, Rotate > Front front side of mesh. ) (If necessary to see the Figure 2-29 . Mesh, front view. Now apply displacement and pr essure boundary conditions.Zero displacement UX along left edge and zero UY along bottom edge. 12. Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Displacement > On Lines Pick the left edge > UX = 0. > OK 13. Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Displacement > On Lines Pick the lower edge > UY = 0. > OK The 1000 lbf load corresponds to a uniform pressure of about 14,000 psi along the ? inch vertical inside edge of the latch retention slot. [1000 lbf/(0. 09375 in. x 0. 75 in. )]. 14.Main Menu > Preprocessor > Loads > Define Loads > Apply > Structural > Pressure > On Lines Plane Stress / Plane Strain 2-21 Select the inside line and set pressure = 14000 > OK Figure 2-30 Applied displacement and pressure conditions. Solve the equations. SOLUTION 15. Main Menu > Solution > Solve > Current LS > OK POSTPROCESSING Comparing the von Mises stress with the material yield stress is an accepted way of evaluating static load yielding for du ctile metals in a combined stress state, so we enter the postprocessor and plot the element solution of von Mises stress, SEQV. 16.Main Menu > General Postproc > Plot Results > Contour Plot > Element Solu > Stress > (scroll down) von Mises > OK Zoom in on the small fillet where the maximum stresses occur. The element solution stress contours are reasonably smooth, and the maximum von Mises stress is around 118,000 psi. Further mesh refinement gives a stress value of approximately 140,000 psi. The small fillet radius of this geometry illustrates the challenges that can arise in creating accurate solutions, however you can easily come within a few percent of the most likely true result using the methods discussed thus far.Figure 2-31 Von Mises stresses. 2-22 ANSYS Tutorial Redesign to reduce the maximum stress requires an increase in the thickness or fillet radius. Look at charts of stress concentration factors, and you notice that the maximum stress increases as the radius of the str ess raiser decreases, approaching infinite values at zero radii. If your model has a zero radius notch, your finite-size elements will show a very high stress but not infinite stress. If you refine the mesh, the stress will increase but not reach infinity.The finite element technique necessarily describes finite quantities and cannot directly treat an infinite stress at a singular point, so don’t ‘chase a singularity’. If you do not care what happens at the notch (static load, ductile material, etc. ) do not worry about this location but examine the stresses and strains in other regions. If you really are concerned about the maximum stress in a particular location (fatigue loads or brittle material), then use the actual part notch radius however small (1/32 for this tutorial); do not use a zero radius.Also examine the stress gradient in the vicinity of the notch to make sure the mesh is sufficiently refined near the notch. If a crack tip is the object of the anal ysis, you should look at fracture mechanics approaches to the problem. (See ANSYS help topics on fracture mechanics. ) The engineer’s responsibility is not only to build useful models, but also to interpret the results of such models in intelligent and meaningful ways. This can often get overlooked in the rush to get answers. Continue with the evaluation and check the strains and deflections for this model as well. 7. Main Menu > General Postproc > Plot Results > Contour Plot > Element Solu > Strain-total > 1st prin > OK The maximum principal normal strain value is found to be approximately 0. 004 in/in. 18. Main Menu > General Postproc > Plot Results > Contour Plot > Nodal Solu > DOF Solution > X-Component of displacement > OK Figure 2-32 UX displacements. Plane Stress / Plane Strain 2-23 The maximum deflection in the X direction is about 0. 00145 inches and occurs as expected at the center of the right-hand edge of the latch retention slot. -9 MAPPED MESHING Quadrilateral m eshes can also be created by mapping a square with a regular array of cells onto a general quadrilateral or triangular region. To illustrate this, delete the last line, AL,all, from the text file above so that the area is not created (just the lines) and read it into ANSYS. Use PlotCtrls to turn Keypoint Numbering On. Then use 1. Main Menu > Preprocessor > Modeling > Create > Lines > Lines > Straight Line. Successively pick pairs of keypoints until the four interior lines shown below are created. Figure 2-33 Lines added to geometry. 2.Main Menu > Preprocessor > Modeling > Create > Areas > Arbitrary > By Lines Pick the three lines defining the lower left triangular area. > Apply > Repeat for the quadrilateral areas. > Apply > OK Figure 2-34 Quadrilateral/Triangular regions. 3. Main Menu > Preprocessor > Modeling > Operate > Booleans > Glue > Areas > Pick All 2-24 ANSYS Tutorial The glue operation preserves the boundaries between areas that we will need for mapped meshing. 4. Main Men u > Preprocessor > Meshing > Size Cntrls > ManualSize > Lines > All Lines Enter 4 for NDIV, No. lement divisions > OK All lines will be divided into four segments for mesh creation. Figure 2-35 Element size on picked lines. 5. Main Menu > Preprocessor > Element Type > Add/Edit/Delete > Add > Solid > Quad 8node 183 > OK (Use the 8-node quadrilateral element for the mesh. ) 6. Main Menu > Preprocessor > Meshing > Mesh > Areas > Mapped > 3 or 4 sided > Pick All The mesh below is created. Applying boundary and load conditions and solving gives the von Mises stress distribution shown.The stress contours are discontinuous because of the poor mesh quality. Notice the long and narrow quads near the point of maximum stress. We need more elements and they need to be better shaped with smaller aspect ratios to obtain satisfactory results. Plane Stress / Plane Strain 2-25 Figure 2-36 Mapped mesh and von Mises results. One can tailor the mapped mesh by specifying how many elements are to be plac ed along which lines. This allows much better control over the quality of the mesh, and an example of using this approach is described in Lesson 4. 2-10 CONVERGENCEThe goal of finite element analysis as discussed in this lesson is to arrive at computed estimates of deflection, strain and stress that converge to definite values as the number of elements in the mesh increases, just as a convergent series arrives at a definite value once enough terms are summed. For elements based on assumed displacement functions that produce continuum models, the computed displacements are smaller in theory than the true displacements because the assumed displacement functions place an artificial constraint on the deformations that can occur.These constraints are relaxed as the element polynomial is increased or as more elements are used. Thus your computed displacements usually converge smoothly from below to fixed values. Strains are the x and/or y derivatives of the displacements and thus depend o n the distribution of the displacements for any given mesh. The strains and stresses may change in an erratic way as the mesh is refined, first smaller than the final computed values, then larger, etc. Not all elements are developed using the ideas discussed above, and some will give displacements that converge from above. (See Lesson 6. In any case you should be alert to computed displacement and stress variations as you perform mesh refinement during the solution of a problem. 2-11 TWO-DIMENSIONAL ELEMENT OPTIONS The analysis options for two-dimensional elements are: Plane Stress, Axisymmetric, Plane Strain, Plane Stress with Thickness and Generalized Plane Strain. The two examples thus far in this lesson were of the third type, namely problems of plane stress in which we provided the thickness of the part. 2-26 ANSYS Tutorial The first analysis option, Plane Stress, is the ANSYS default and provides an analysis for a part with unit thickness.If you are working on a design problem in which the thickness is not yet known, you may wish to use this option and then select the thickness based upon the stress, strain, and deflection distributions found for a unit thickness. The second option, Axisymmetric analysis is covered in detail in Lesson 3. Plane Strain occurs in a problem such as a cylindrical roller bearing caged against axial motion and uniformly loaded in a direction normal to the cylindrical surface. Because there is no axial motion, there is no axial strain.Each slice through the cylinder behaves like every other and the problem can be conveniently analyzed with a planar model. Another plane strain example is that of a long retaining wall, restrained at each end and loaded uniformly by soil pressure on one or both faces. The Generalized Plane Strain feature assumes a finite deformation domain length in the Z direction, as opposed to the infinite value assumed for standard plane strain. 2-12 SUMMARY Problems of stress concentration in plates subject to in-plane loadings were used to illustrate ANSYS analysis of plane stress problems.Free triangular and quadrilateral element meshes were developed and analyzed. Mapped meshing with quads was also presented. Similar methods are used for solving problems involving plane strain; one only has to choose the appropriate option during element selection. The approach is also applicable to axisymmetric geometries as discussed in the next lesson. 2-13 PROBLEMS In the problems below, use triangular and/or quadrilateral elements as desired. Triangles may produce more regular shaped element meshes with free meshing.The six-node triangles and eight-node quads can approximate curved surface geometries and, when stress gradients are present, give much better results than the four-node quad elements. 2-1 Find the maximum stress in the aluminum plate shown below. Use tabulated stress concentration factors to independently calculate the maximum stress. Compare the two results by determining the percen t difference in the two answers. Convert the 12 kN concentrated force into an equivalent pressure applied to the edge. Plane Stress / Plane Strain 2-27 Figure P2-1 -2 Find the maximum stress for the plate from 2-1 if the hole is located halfway between the centerline and top edge as shown. You will now need to model half of the plate instead of just one quarter and properly restrain vertical rigid body motion. One way to do this is to fix one keypoint along the centerline from UY displacement. Figure P2-2 2-28 ANSYS Tutorial 2-3 An aluminum square 10 inches on a side has a 5-inch diameter hole at the center. The object is in a state of plane strain with an internal pressure of 1500 psi. Determine the magnitude and location of the maximum principal stress, the maximum rincipal strain, and the maximum von Mises stress. Note that no thickness need be supplied for plane strain analysis. Figure P2-3 2-4 Repeat 2-3 for a steel plate one inch thick in a state of plane stress. 2-5 See if yo u can reduce the maximum stress for the plate of problem 2-1 by adding holes as shown below. Select a hole size and location that you think will smooth out the ‘stress flow’ caused by the load transmission through the plate. Figure P2-5 2-6 Repeat 2-1 but the object is now a plate with notches or with a step in the geometry. (See the next figure. ) Select your own dimensions, materials, and loads.Use published stress concentration factor data to compare to your results. The published results are for plates that are relatively long so that there is a uniform state of axial stress at either end relatively far from notch or hole. Create your geometry accordingly. Plane Stress / Plane Strain 2-29 Figure P2-6 2-7 Solve the seatbelt component problem of Tutorial 2B again using six node triangular elements instead of the quadrilaterals. Experiment with mesh refinement. Turn on Smart Sizing using size controls to examine the effect on the solution. See if you can compute a maxi mum von Mises stress of around 140 kpsi. -8 Determine the stresses and deflections in an object ‘at hand’ (such as a seatbelt tongue or retaining wall) whose geometry and loading make it suitable for plane stress or plane strain analysis. Do all the necessary modeling of geometry (use a CAD system if you wish), materials and loadings. 2-9 A cantilever beam with a unit width rectangular cross section is loaded with a uniform pressure along its upper surface. Model the beam as a problem in plane stress. Compute the end deflection and the maximum stress at the cantilever support. Compare your results to those you would find using elementary beam theory.Figure P2-8 Restrain UX along the cantilever support line, but restrain UY at only one keypoint along this line. Otherwise, the strain in the Y direction due to the Poisson effect is prevented here, and the root stresses are different from elementary beam theory because of the singularity created. (Try fixing all node points in UX and UY and see what happens. ) Select your own dimensions, materials, and pressure. Try a beam that’s long and slender and one that’s short and thick. The effect of shear loading becomes more important in the deflection analysis as the slenderness decreases.
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