School Uniform Essay Example | Topics and Well Written Essays - 750 words

School Uniform - Essay Example Brunsma argues that uniforms help to save money for families by ensuring that children do not pressurize their parents to buy them expensive clothes (38). However, uniforms are not cheap and must be bought year after year as the children grow bigger and older uniform no longer fits them. Moreover, children will still demand new uniform due to wear and tear. Two sets of uniforms are required thereby increasing the cost of education. Emphasis on school uniforms also leads to the emergence of cartels that control the market charging exorbitant prices to parents because most of them must buy them under the guise of â€Å"back to school offers† (Gouge, 82). During elementary level, I and my siblings exerted undue pressure on our parents to buy new uniforms as a result of the â€Å"back to school† excitement. Children and their parents flocked uniform shops creating a sharp rise in demand that caused price increases. It is also important to understand that buying uniforms doe s not mean that children will not demand regular designer clothes suitable for seasons such as summer and winter. It is therefore obvious that school uniforms do not help parents to save money.   Haydon supports the idea of school uniforms as a symbol of belonging to a certain organization. It is viewed as a symbol of pride that also creates a sense of identity for the school and the students within the community, thereby promoting learning. It is part of an organizational culture of a school and demonstrates that students appreciate being part of it (25).

Occupy Wall Street Movement Assignment Example | Topics and Well Written Essays - 1500 words - 2

Occupy Wall Street Movement - Assignment Example Thus, it can broadly be stated that all the aforementioned issues ultimately paved the way towards the emergence of this particular movement (Kim, 2011). The paper intends to analyze the moral as well as the economic implications involved in the movement. Various aspects such as the analysis of the identified implications against the Kantian, utilitarian as well as virtue ethics and the determination of the individuals or entities liable for income disparity along with inappropriate wealth distribution particularly in the US will be taken into concern. Besides, a suggestion regarding an equitable outcome from the movement that would be appropriate for capitalistic society and the prediction concerning whether the movement will continue, fad away or turn into another perspective will also be discussed in the paper. The moral implications that have been involved in the movement i.e. Occupy Wall Street movement contain numerous important aspects that include the contemplation of individual responsibility instead of moral responsibility and predominance of self-interest. With regard to the moral implications, the movement has been viewed to remain significantly focused upon determining the role of hierarchical authorities that is based upon wealth or different sources of power. In accordance with the viewpoints of the protestors of the movement, the role of any government is to safeguard as well as to empower every citizen of a nation through enhancing different avenues of growth. In this similar context, the areas include health as well as education, transportation, public infrastructure, trade policies, art and culture, scientific research, public lands, and resources. It has been viewed that the movement relating to moral implications has been based upon certain moral guidelines.

Trauma Narratives in Post-War and Postcolonial Fiction

Trauma Narratives in Post-War and Postcolonial Fiction Trauma Narratives in Post-War and Postcolonial Fiction â€Å"There are wounds that never show on the body that are deeper and more hurtful than anything that bleeds.† Laurel K. Hamilton, Mistral’s Kiss â€Å"The traumatized soul finds no rest in conditions of peace. It’s forever questing for violence, for action, for the same combination of factors which gave rise to it in the first place.† Matthew S. Williams I. Introduction From a hunting-gathering economy and communal property, societies have developed to today’s market-oriented, profit-driven economies and privatization. In the span of history, the transitions and developments of nations are determined by its struggle for survival. These include the desire to expand territories for raw materials and showcase of power which have led to the wars and conflicts that we know from our history books. We now live in an age of global economies, high-tech industries, cyber technology, and an even more complex geopolitics. Modernity has caused a lot of suffering aside from its advantages. We have advanced in curing a number of diseases, replaced manual labor with automated machines, revved up academic research and discovered alternative energy resources yet we still face socio-political, economic, cultural and environmental issues today. These include demanding jobs but below average salaries, unmet social needs and services, political instability and even environmental disasters. These lead to civil unrest, rise of assorted nationalist and separatist movements and other issue-specific mobilizations, and even armed resistance. There are also intangible forces at play which contribute to humanity’s dilemma. Traditional values, social constraints, taboos, inequalities, and the role of religion reinforce the contradictions experienced by an individual. One should also keep in mind the role of history. Stronger nations invade and occupy smaller and weaker ones to expand their influence and enforce them to be their subjects. A good example for this is the Spanish colonization of the Philippines and the historical events that followed. These unsettling experiences demoralize people and poses great effects to their mentality. This paper will explore the function of literature as a testimony of traumatic experiences and as an embodiment of individual and collective memory. The works of John Updike, William Golding and F. Sionil Josà ©, a Filipino English-language writer, will be the focus of this research of post-war and postcolonial fiction. Their works can be read as manifestations of trauma and demonstrate the psychological effects of historical and catastrophic events such as armed conflicts and the post-war, postcolonial condition as they are experienced by the characters in their novels. In addition, we will look at the authors’ style of writing in preserving memories of psychic pain and suffering and how successful they are in representing traumatic experiences in fiction. Using different literary theories, we will also try to explore several issues such as identity, social and gender roles and social classification among others. Through reading these literary texts, we can hope to see more in the historical realm and uncover long forgotten issues of the past and link it to the present. My thesis is divided into several parts. The first part will define trauma and establish the existing theoretical bases of its studies in literature. Here I shall determine how trauma is represented in literature and how it contains memories of pain and suffering and how it functions in its recollection. Trauma will be analyzed in this chapter as not being a theoretically ‘fixed-in-time’ phenomenon but rather unpredictably experienced through different contexts that reminds a traumatized individual of a horrifying experience. The next chapter is where I look at the thin line between trauma and fiction. I shall recall the basic functions of literature and understand the significance of trauma in literature. There is that difficulty of articulating memories of a dark past and an overwhelming experience whether it is recent or long forgotten, and through writing fiction an individual is provided an opportunity to express it in a less obtrusive method instead of an intrusive one-to-one conversation. I shall also evaluate the healing function of writing trauma in fiction as an individual and a collective. The following chapter will be the introduction of the works of John Updike, an American writer, William Golding, an English writer, and Francisco Sionil Josà ©, a Filipino English-language writer. Here I will discuss the contexts of trauma in their works and tackle the themes in their works, as well as, the different literary elements that complete their whole work that embody memories of a traumatic past such as memories of war, resistance, and other modes of violence. The last part will be the conclusion and synthesis of the significance of writing trauma narratives in fiction and the highlights of representation of memory and trauma. II. Theories of Trauma Theories of trauma are not new in the field of literary studies. In her introduction to Trauma: Explorations in Memory, Cathy Caruth states that the issue of trauma is derived from different discourses which include psychiatry, psychoanalysis and sociology that addressed the questions after catastrophic wars (Caruth 3: 1995). Today, there has been an even more increasing interest in trauma as a research topic in literature. Works such as Laurie Vickroy’s Trauma and Survival in Contemporary Fiction and Debora Horvitz’s Literary Trauma: Sadism, Memory, and Sexual Violence in American Women’s Fiction are some of the recent studies. By 1980, trauma became a â€Å"solid status of inquiry† and became known as Post-Traumatic Stress Disorder (PTSD) by the American Psychiatric Association (Caruth 3). This phenomenon included what the soldiers experienced after combat such as symptoms of â€Å"shell shock, combat stress, delayed stress syndrome, and traumatic neurosis† (Caruth 3). Due to its official recognition as a pathological classification, it provided means in diagnosing other reactions to extreme events that affect the human psyche. These include not only the effects of fighting in the battlefield or aftereffects of an environmental disaster, but also rape, child abuse, and other violent situations (Caruth 3). In her master dissertation, Minczingerovà ¡ points out that traumatic experience â€Å"fails to be integrated into the consciousness and continues to haunt the survivors later on through flashbacks, dreams and intrusive thoughts. (2)† In the most general definition, Caruth defines trauma as an overwhelming experience of sudden catastrophic events (Caruth 29: 1996). She further states that: From [Freud’s] early claims, in the Project for a Scientific Psychology, that a trauma consist of two scenes—the earlier (in childhood) having sexual content but no meaning, the later (after puberty) having no sexual content but sexual meaning—to his later claims, in Moses and Monotheism, that trauma occurs only after latency period, Freud seems to have been concerned [†¦] with the way in which trauma is not a simple or single experience of events but that events, insofar as they are traumatic, assume their force precisely in their temporal delay. (Caruth 9: 1995) This brings us to Michelle Balaev’s point in literary criticism on trauma in fiction in which she underlines the importance of â€Å"the relationship between psychic trauma, memory and landscape.† Her interest on the concept of trauma is not it being a temporal but rather a spatial phenomenon since it is not just registered in one setting but rather experienced further and tends to â€Å"resurface in flashbacks, nightmares, and repetitive reenactments (Rodi-Risberg 2012).† As a subject that involves the human psyche, it is imperative to discuss the contributions of Sigmund Freud to the field of trauma studies. Minczingerovà ¡ points out that: He is still a prominent figure at least in the cultural and literary studies of trauma (even though he is often dismissed in therapeutic and medical discourses), and also because this thesis draws upon some of his concepts, albeit, as it will be pointed out, in a slightly different way from Freud’s intended usages (3). Freud was troubled about the soldiers who returned home after the First World War who â€Å"displayed symptoms of what came to be known as shell shock (Minczingerovà ¡ 3).† He coined the term â€Å"repetition compulsion† which concluded his observation that a person who experienced an overwhelming situation such as war tend to be obsessed at reliving or reenacting the event. A. Running away as a defense mechanism in Updike’s Rabbit, Run Around 1958, John Updike suffered an existential crisis, one that have been brewing for several years. He explained in his work Odd Jobs, â€Å"Amid my new responsibilities, I felt fearful and desolate, foreseeing, young as I was, that I would die, and that the substance of the earth was, therefore, death.† He was saved from this abyss by two writers, namely, Sà ¸ren Kierkegaard (Danish existentialist writer) and Karl Barth (German theologian). Aside from giving answers to his religious and philosophical questions, both writers provided Updike the necessary tools to create his own theological and aesthetic vision which have influenced his literary writing, circling on matters of moral debate and goodness of man. And Rabbit, Run tells us a story of a person going through this kind of conflict, his contradictions in life and how he deals with them. The central figure of the novel is Harry â€Å"Rabbit† Angstrom, 26-year-old, former high school basketball MVP, who is trapped in a failing marriage, and has a life full of frustration, dissatisfaction and weariness that results to his escapism and therefore hurting those around him. He is married to Janice Springer-Angstrom only because he got her pregnant with Nelson, who is now a toddler. Wanting to escape, he abandons both Nelson and Janice who is already pregnant with their second child Rebecca June. He goes to his former coach Marty Tothero to ask help or guidance with his life. Instead, they go out to see girls and Rabbit meets Ruth, winding up together. While living with Ruth, Jack Eccles, a young local minister, tries to fix Rabbit and Janice’s marriage. At first, Rabbit was dismissive about the idea of going back to her but when he realizes she was going to labor, he leaves Ruth and rushes to the hospital. After seeing Janice’s condition, Rabbit sort o f falls in love with her again. Rabbit then becomes consumed with his carnal desire for Janice but she (after a 9-month pregnancy, being left by Rabbit for another woman, and a hard labor) did not have the capability of having sex with him. It was that night when he wanted to make love with her but then she shoved him off telling him that she is not a whore. This frustration pushes him to walk away again. This time, making Janice even more miserable, thinking that Rabbit left for good. She continues her drinking and smoking habit but even worse this time. One day, she got so drunk that she drowns their baby, Rebecca, in the bathtub. Upon hearing the news, Rabbit goes back home. At the funeral, he tells Janice it was his fault. But at the end of the day, he lashes out and puts the blame on Janice. He runs away again, going back to Ruth. Apparently, Ruth is pregnant and Rabbit is the father. He is happy and he tells her he wants them to get married. But Ruth tells him that there will be nothing between him and her an d the baby if he does not divorce his wife, Janice. He agrees to this term, then decides to go out and buy some food. On the way, he starts to doubt his decisions, the hard choice of leaving Janice for Ruth and the future of his son, Nelson. All these put him on so much pressure so he, as you may expect, runs away again. Rabbit Angstrom’s story does not require much philosophizing. His leaving is an impulsive action to escape from being trapped in a net. To understand his life, we must look at the political events and other historical forces at that time, which he barely was aware of. Through this method, we will be aware of the apparent themes in this novel. He was born in the thirties when critical historical events were happening and affected the international scene, mainly the Great Depression which was the best platform for other world powers to invade weaker nations. When Franklin Roosevelt was inaugurated as the president of the United States, he initiated the social welfare program called â€Å"New Deal† to combat the effects of and recover from the Great Depression. Employment rate skyrocketed due to America’s participation in the Second World War that resulted from the economic and political crisis. This has led to forcing most men to the combat field and women taking o ver men’s jobs. Returning from the battlefield, men grew weary and women returned to their mostly boring domestic roles. Rabbit, being one of those who gave service during the war, came back home wanting to satisfy himself with all the pleasure he can get. But he feels incomplete and unsatisfied which led him to seek for divine guidance that can light up his way or at least a human being he can look up to like his coach Tothero. He goes bored and weary of old age so he wants to relieve his younger days. This can be seen in the opening of the novel when he joins a group of young boys playing basketball and also his giving in to his sexual fantasies. However, Janice and Nelson plus his personal issues with his parents keep him anchored. This is why he always tries to run from everything, to taste freedom and find a new purpose in life. But while he runs away, everything catches up with him. Janice, who I consider a victim of her environment, is bound to an unpleasant fate. Getting pregnant before marriage was considered immoral during her younger days so she was forced to marry Rabbit. However, their marriage somehow locks her down as well. Women were expected to play domestic roles and Janice, probably thinking of achieving greater things in life, became frustrated and bored resulting to her being alcoholic and a smoker. Moreover, the media influenced many housewives on the illusion of beauty. It should be noted that Barbie became a popular icon during that time and other famous women who were considered models of perfection. Ideal families were also portrayed on regular television shows which motivated women to struggle for a perfect household. Somehow, this fact pressured her too, aside from Rabbit’s departure and living with another woman that led to her despair. Looking at the novel critically, we will realize that Rabbit’s actions are connected to his environment. It begs the question how he was raised by his parents and if he had a healthy childhood. His search for the divine, for someone he can look up to reveals the fact that he is yearning for parental love that his parents was probably not able to satisfy. A scene in the novel when Rabbit sneaks to his parents’ house and looks through the window, and describes how his parents take care of his son Nelson, means that there is inside of him a longing for affection. Yet he cannot go back to his childhood and make things happen the way he wants it to be. This creates a feeling of nothingness inside of him. However, given his freedom as an adult he is completely free to do anything. But with no one who can genuinely guide him will eventually lead to his downfall.

Bell Jar summary :: essays papers

Bell Jar summary Many have paralleled Sylvia Plath’s novel, The Bell Jar, to her very own life. Plath is known for her tormented life of constant depression and disappointments, causing her to end her life early at the young age of 30. The time frame in which the book is in matches the times when she is enlisted in many mental institutes and ultimately her suicide. The story of Esther Greenwood also tells the feelings and emotions of Sylvia Plath. Other characters in the novel are said to be in relation to characters in the author’s life. The novel begins where Esther is just about halfway through her job as Mademoiselle, a fashion magazine. She and many other girls received this opportunity because of their exceptional writing abilities. Even though this she had waited for this chance for a year, she is actually disappointed because she had expected more from the other prizewinners. â€Å"These girls looked awfully bored to me. I saw them on the roof yawning and painting their nails and trying to keep their Bermuda tans, and they seemed bored as hell... Girls like that make me sick.† (Pg. 4) A couple other unfortunate events also led her to be depressed at her stay in the hotel. At a dinner gathering, Esther ate a lot of crabmeat that happened to be poisoned. She passes out and awakes in her room. Her recovery is slow and agonizing. Another social event causes yet again another mishap. Doreen, Esther best friend there, sets Esther up with a friend of Doreen’s boyfriend to go to a party. There, the bli nd date attempts to sexually assault, but Esther resists and walks away with her dignity. After returning to the hotel, Esther takes no care of the assault and just carries on. Later, she finds out that her on and off boyfriend, Buddy Willard, is actually not a virgin. â€Å"At first I thought he must have slept with the waitress only that once, but when I asked how many times, just to make sure, he said he couldn’t remember but a couple of times a week for the rest for the summer.† Knowing this, she thought it to be okay if she were to have an affair also. On a date with Constantin, he invites her to his room, but to her dismay, nothing happens.

American Writers Essay

List of American Novels for Research Project English 11H Historical/War Red Badge of Courage, Stephen Crane Killer Angels, Michael Shaara A Farewell to Arms, Ernest Hemingway The Things They Carried, Tim O’Brien Cold Mountain, Charles Frazier My Brother Sam is Dead, JL Collier African-American Beloved, Toni Morrison (mature themes) I Know Why the Caged Bird Sings, Maya Angelou Native Son, James Baldwin The Color Purple, Alice Walker (mature themes) Invisible Man, Ralph Ellison Their Eyes Were Watching God, Zora Neale Hurston Malcom X (autobiography- lengthy) A Lesson Before Dying, Ernest Gaines. The Autobiography of Miss Jane Pittman, Ernest Gaines Go Tell it on the Mountain, James Baldwin Black Boy, Richard Wright (memoir) Dystopian/Futuristic/Science Fiction Ender’s Game, Orson Scott Card Slaughterhouse 5, Kurt Vonnegut Catch-22, Joseph Heller The Giver, Lois Lowry Martian Chronicles, Ray Bradbury Realism/Naturalism/Regionalism The Call of the Wild, Jack London White Fang, Jack London O’Pioneers, Willa Cather My Antonia, Willa Cather Maggie, Girl of the Streets, Stephen Crane The Jungle, Upton Sinclair Adventures of Tom Sawyer, Mark Twain Miscellaneous Modern/Contemporary novels The Secret Life of Bees, Sue Monk Kidd. The Natural, Bernard Malamud (baseball; Jewish myth) One Flew Over the Cuckoo’s Nest, Ken Kesey (set in a mental asylum) House on Mango Street, Sandy Cisneros Of Mice and Men, John Steinbeck The Joy Luck Club, Amy Tan (Chinese-American culture) The Help, Kathryn Stockett (set in 1960s; about African-American maids in the South) Shoeless Joe, WP Kinsella (baseball) Franny and Zooey, by JD Salinger (from 1950’s; If you have an interest in world philosophy or eastern religion, you’d probably like this. ) The Outsiders, S. E. Hinton The Bell Jar, Sylvia Plath (mature themes) Research Novel Lottery Preparation. Native American Lone Ranger and Tonto Fistfight in Heaven, Sherman Alexie Absolutely True Diary of a Part-time Indian, Sherman Alexie Ceremony, Leslie Marmon Silko Quest/Journey On the Road, Jack Kerouac The Old Man and the Sea, Ernest Hemingway The Road, Cormac McCarthy Dark Romanticism The Scarlet Letter, Nathaniel Hawthorne (set in Puritan New England; challenging) ark Roma nticis m he Scarlet Letter For our project, you will read one of the books on this list and (later) research the reasons this has become a significant member of the American literary canon. (What literary elements make it unique or powerful? What impact has this work had on our history or way of thinking? ) During our next class, we will conduct a lottery so that each student has a different title. To help insure that you end up with a title that you will enjoy, please spend 20-30 minutes choosing 4 titles from the list that you will be pleased to read and research. You ARE NOT allowed to read any book that you have previously read. I strongly suggest you do some Internet searches on various titles to examine what those books are all about, and to determine if their content might appeal to you. You also need to make sure ahead of time that your choices are okay with your parents. Remember, we will draw names and choose titles, so it’s highly likely you won’t get your first choice. You may, in fact, want to come up with more than four choices! Four top choices: 1_________________________________________________________________________ 2_________________________________________________________________________ 3_________________________________________________________________________ 4_________________________________________________________________________ Please see side two for list of titles—————————————————————————–?

Tolerance Analysis

A Comprehensive System for Computer-Aided Tolerance Analysis of 2-D†¦ http://adcats. et. byu. edu/Publication/97-4/cirp_2_7_97a. html 7. 0 ASSEMBLY TOLERANCE SPECIFICATIONS An engineering design must perform properly in spite of dimensional variation. To achieve this, engineering design requirements must be expressed as assembly tolerance limits. The designer must assign limits to the gaps, clearances and overall dimensions of an assembly which are critical to performance.Assembly tolerance limits are applied to the statistical distribution of the assembly variations predicted by tolerance analysis to estimate the number of assemblies which will be within the specifications. Designers need to control more than just gaps and clearances in assemblies. Orientation and position of features may also be important to performance. To be a comprehensive design tool, a tolerance analysis system must provide a set of assembly tolerance specifications which covers a wide range of common des ign requirements. A system of assembly tolerance specifications patterned after ANSI Y14. 5 has been proposed [Carr 93].Those ANSI Y14. 5 feature controls which require a datum appear to be useful as assembly controls. However, there is a distinct difference between component tolerance and assembly tolerance specifications, as seen in Fig. 9. In the component tolerance specification shown, the parallelism tolerance zone is defined as parallel to datum A, a reference surface on the same part. By contrast, the assembly parallelism tolerance defines a tolerance zone on one part in the assembly which is parallel to a datum on another part. In order to distinguish an assembly tolerance specification from a component specification, new symbols have been proposed.The feature control block and the assembly datum have been enclosed in double boxes. Fig. 9 Comparison of component and assembly tolerance specifications. 8. 0 MODELING PROCEDURES AND RULES The ability to model a system is a funda mental skill for effective engineering design or manufacturing systems analysis. Unfortunately, few engineers know how to construct variational models of assemblies beyond a 1-D stack. This is primarily because the methods have not been established. There is little treatment of assembly modeling for tolerance analysis in engineering schools or texts.Until engineers learn how to model, tolerance analysis will never become widely used as have other CAD/CAE tools. A consistent set of modeling procedures, with some guiding rules for creating vector assembly models, allows for a systematic approach which can be applied to virtually any assembly. The steps in creating a model are: 1. Identify the assembly features critical to the assembly. Locate and orient each feature and specify the assembly tolerances. 2. Locate a datum reference frame (DRF) for each part. All model features will be located relative to the DRFs. 3.Place kinematic joints at the points of contact between each pair of ma ting parts. Define the joint type and orient the joint axes. These are the assembly constraints. 4. Create vector paths from the DRF on each part to each joint on the part. The paths, called datum paths, must follow feature dimensions until arriving at the joint. Thus, each joint may be located relative to the DRF by controlled engineering dimensions. 5. Define the closed vector loops which hold the assembly together. The datum paths defined in Step 2 7 of 14 5/11/2011 4:27 PM A Comprehensive System for Computer-Aided Tolerance Analysis of 2-D†¦ ttp://adcats. et. byu. edu/Publication/97-4/cirp_2_7_97a. html become segments of the vector loop. A vector loop must enter a part through a joint and leave through another joint, passing through the DRF along the way. Thus, the vector path across a part follows the datum path from the incoming joint to the DRF and follows another datum path from the DRF to the outgoing joint. 6. Define open vector loops to describe each assembly tolera nce specification. For example, for an assembly gap, the loop would start on one side of the gap, pass through the assembly, and end at the other side of the gap. 7.Add geometric variations at each joint. Define the width of the tolerance zone and length of contact between the mating parts as required. The nature of the variation and direction is determined by the joint type and joint axes. Other variations, such as position, may be added at other feature locations. Modeling rules are needed to ensure the creation of valid loops, a sufficient number of loops, correct datum paths, etc. For example, an important set of rules defines the path a vector loop must take to cross a joint. Each joint introduces kinematic variables into the assembly which must be included in the vector model.Fig. 10 shows the vector path across a 2-D cylinder-slider joint. The rule states that the loop must enter and exit the joint through the local joint datums, in this case, the center of the cylinder and a reference datum on the sliding plane. This assures that the two kinematic variables introduced by this joint are included in the loop, namely, the vector U in the sliding plane and the relative angle f at the center of the cylinder, both of which locate the variable point of contact in their corresponding mating parts. Fig. 11 shows a similar vector path through a 3-D crossed cylinders joint.A more complete set of modeling rules is described in [Chase 94]. Fig. 10: 2-D vector path through a joint Fig. 11 3-D vector path through a joint 9. 0 MODELING EXAMPLE The process of creating an assembly tolerance model for analysis is illustrated in the figures below for a seatbelt retraction mechanism. The device is an inertial locking mechanism for the take-up reel. One of the critical assembly features is the gap between the tip of the locking pawl and the gear, as shown in Fig. 12. The assembly is of reasonable complexity, with about 20 dimensional variations and several geometric variati ons as contributing sources.The contribution by each variation source depends on the sensitivity of the gap to each component variation. Fig. 13 shows the DRFs for each part and local feature datums which define model dimensions. 8 of 14 5/11/2011 4:27 PM A Comprehensive System for Computer-Aided Tolerance Analysis of 2-D†¦ http://adcats. et. byu. edu/Publication/97-4/cirp_2_7_97a. html Fig. 12 Example 2-D assembly Fig. 13 Part DRFs and feature datums. In Figure 14, the kinematic joints defining the mating conditions are located and oriented. Clearance in the rotating joints was modeled by two methods.In the first case, the shafts were modeled as revolute joints, centered in the clearance, with clearance variation added as an equivalent concentricity. In the second case, the CAD model was modified so each shaft was in contact with the edge of the hole, modeled by parallel cylinder joints, and variation was determined about this extreme position. After the joints have been locat ed, the assembly loops can then be generated, as shown in Fig. 15. To simplify the figure, some of the vectors are not shown. Fig. 14 Kinematic joints define mating conditions. Fig. 5 Vector loops describe assembly. Models for geometric variation may then be inserted into the vector assembly model, as shown in Fig. 16. The completed CATS model, in Fig. 17, is ready for assembly tolerance analysis. 9 of 14 5/11/2011 4:27 PM A Comprehensive System for Computer-Aided Tolerance Analysis of 2-D†¦ http://adcats. et. byu. edu/Publication/97-4/cirp_2_7_97a. html Fig. 16 Geometric variation sources are added. Fig. 17 The completed CATS model. Figure 18 show a 3-D CATS model overlaid on a swashplate cam and follower mechanism. Fig. 18 3-D CATS model. 10. 0 TOLERANCE ANALYSISThe analysis approach used within the CATS system is based on linearization of the assembly equations and solution for the variations by matrix algebra. A detailed description with examples may be found in [Chase 95, 96] and [Gao 97]. The linearized method provides an accurate and real-time analysis capability that is compatible with engineering design approaches and tools. Vector assembly models can be used with any analysis system. Gao used the CATS Modeler as a graphical front end for 10 of 14 5/11/2011 4:27 PM A Comprehensive System for Computer-Aided Tolerance Analysis of 2-D†¦ http://adcats. et. byu. du/Publication/97-4/cirp_2_7_97a. html a Monte Carlo simulator [Gao 93]. An iterative solution was used to close the vector loops for each simulated assembly. Histograms for each assembly feature being analyzed were generated from the computed assembly dimensions. A comparison of the linearized approach with Monte Carlo analysis is presented in [Gao 95]. 11. 0 CAD IMPLEMENTATION Fig. 19 shows the structure of the Computer-Aided Tolerancing System integrated with a commercial 3-D CAD system. The CATS ® Modeler creates an engineering model of an assembly as a graphical and symbolic overla y, linked associatively to the CAD model.Pop-up menus present lists of joints, datums, g-tols and design specs to add to the CAD model. The model is created completely within the graphical interface of the CAD system. There are no equations to type in to define mating conditions or other assembly relationships. CATS is tightly integrated with each CAD system, so it becomes an extension of the designer's own CAD system. Current CAD implementations include: Pro/ENGINEERa (TI/TOL 3D+), CATIAa, CADDS5a, and AutoCADa; (AutoCATS). Fig. 19 The CATS System Architecture The CATS Analyzer accesses the assembly tolerance model that was created and stored in the CAD system.The Analyzer has built-in statistical algorithms to predict variation in critical assembly features due to process variation. It features built-in algorithms for tolerance synthesis, which re-size selected tolerances to meet target assembly quality levels. Matrix analysis gives instant feedback for any design iteration or â⠂¬Å"what-if† study. The user interface is standard XWindows Motif, with multiple windows, scroll bars, pop-up menus, dialog boxes, option buttons, data fields and slide bars for data entry, etc. The designer is in complete control of the tolerance analysis/design process.Graphical plots give visual feedback in the form of statistical distributions, ranked sensitivity and percent contribution plots. Engineering limits are shown on the distribution, with corresponding parts-per-million reject values displayed. The current status of the CATS Modeler and Analyzer, with respect to ease of use by an interactive graphical user interface and internal automation are summarized in Table 1 and Table 2. Table 1. Current status of assembly modeling CAD implementation Modeling Task Graphical Automation Level 11 of 14 5/11/2011 4:27 PM