Georgia O’Keeffe Essays -- Historiography

Georgia O’Keeffe is one of the most famous and controversial painters known to America. According to art critic Lisa Mintz Messinger, â€Å"She [Georgia O’Keeffe] left behind a rich legacy of American images that were tied to the land. These images and her own pioneering spirit, established an illustrious reputation in America very early on in her career† (Messinger 17). O’Keeffe is best known for her large paintings of flowers, the New York skyline and scenes from New Mexico. Ever since Georgia O’Keeffe began showing her work in 1916, critics have had different opinions on what her paintings represented. One of the biggest debates regarding her paintings has been whether or not her paintings were erotic. Some of the biggest critics of her works are Robert Hughes, Lisa Mintz Messinger, Katherine Hoffman and Georgia O’Keeffe herself. All four of these people have helped shape O’Keeffe into an iconic figure of sexually charged pai ntings. Georgia O’Keeffe first came into the lime light after her friend Anita Pollitzer submitted some of O’Keeffe’s works to the famous Alfred Stieglitz (Hoffman 5). Even from these first charcoal drawings, critics noticed the eroticism in her works of art. One of the biggest critics of her work is the noted Robert Hughes. In his book, American Visions: The Epic History of Art in America, Hughes explores American artists’ works, including O’Keeffe. According to Hughes, â€Å"Much ink has been spilled on the topic of whether O’Keeffe ever set out to use specifically genital images; she herself indignantly denied it, and especially refused to countenance any sexual interpretation of the large close-ups of flowers she painted in the twenties. To deny the sexuality of a painting like Black Iris III, 1926,... ...a Bricker. â€Å"Review: Stieglitz.† Stieglitz 55.2 (1996): 105-106. Web. 23 October 2009. Cowart, Jack, et al. Georgia O'Keeffe: Art and Letters. Washington; Boston: National Gallery of Art; New York Graphic Society Books, 1987. Print. Hoffman, Katherine, and Georgia O'Keeffe. An Enduring Spirit: The Art of Georgia O'Keeffe. Metuchen: Scarecrow Press, Inc., 1984. Print. Hughes, Robert. American Visions: The Epic History of Art in America. 1st ed. New York: Alfred A. Knopf, Inc., 1997. Print. Messinger, Lisa Mintz, Metropolitan Museum of Art, and Georgia O'Keeffe. Georgia O'Keeffe. New York: Thames and Hudson Inc.; Metropolitan Museum of Art, 2001. Print. Middleton, Ken.â€Å"1920’s: American Women through Time.†www.frankmtsu.edu. N.d. Web. 25 Sep. 2009. â€Å"Introduction to Modern Art.† metmuseum.org. The Metropolitan Museum of Art. 18 June 2009. Web. 25 Sep. 2009.

Brave New World7 :: Essays Papers

Brave New World7 From my readings in Aldous Huxley's Brave New World I have noticed most of the World State citizens remain in a childish state of mind all of their entire lives from playing games all day to having instant gatification from their problems. This bothers me very much because in the real world people must work for what they want. Instead the citizens of this deranged culture are taken care of for their whole lives like children. In Brave New World the citizens of the World State take soma for instant gratification from everything much like kids today smoke marijuana to get away from their problems. For example when Bernard finds out that he is being sent to Iceland he takes some soma to relieve himself from his problem. After finding out that he was being sent to Iceland, "Lenina pursuaded him to swallow four tablets of soma. Five minutes later roots and fruits were abolished; the flower of the present rosily blossomed." (104) The soma Bernard took was because he wanted his problem to go away and hoped someone other then himself would fix it. The next example of the citizens being taken care of like children, was that they were taught by hypnopedia what to think and believe and to stick by it like a stubborn child. An example of this is when Bernard wants to think on his own, which is very unsual for these people, and Lenina repeats phrases she heard during hypnopedia to get him to take some soma to get rid of those thoughts: " A gramme in time saves nine, she says blindly" and "One cubic centimetre cures ten gloomy sentiments."(89) Bernard is frustrated by her inability to think but Lenina then finally nags him to the point that he takes the soma to make her stop. By doing this Lenina proves she can't think independently like a stubborn child would try to get its way. The last example of these citizens acting much like children is that all day they play elaborate games like elevator squash and obstacle golf. You never find out if they have any real responsibilitys at all but they play games during the day. At one point Bernard bemoans Lenina's tendencies: "...wretched that she should have thought it was a perfect afternoon for obstacle golf...." (64) You must wonder how they could play this in the afternoon if they have any responsibilitys at all.

Problems Of Modernization In Developing Nations Essays -- essays resea

Problems of Modernization in Developing Nations The economic situation which exists in the developing world today, is the result of the relationship between the modern, and developing nations of the world. Modernized nations benefited from this relationship because it gave them access to natural resources. However, because of this relationship, many developing nations now suffer from severe problems. These nations are attempting to change the situation in which they struggle. A political cartoon I have recently seen illustrated the economic relationship between the industrialized world and the developing world. It shows that the industrial nations, The United States and Europe, are located in the northern hemisphere. On the other hand most of the developing world, Central and South America and Africa, are found in the southern hemisphere. The "well fed", well dressed individual holding the industrialized world indicates that the modernized nations of the world are prosperous, and have a high standard of living. The skinny, poorly dressed individual holding the developing world indicates that the developing nations of the world are not prosperous, and have a lower standard of living than do industrialized nations. Both individuals are supporting each other in such a way that if one is removed, the other will fall. Without resources to use, industry would not be able to maintain its existence. Likewise, without a market for their resources, or the products of indus...

A Growing “Threat” to Society Essay

The Internet is one of the most powerful sources of information today. Thus, it has the capacity to enlighten, as well as to mislead. This double-edged potential has turned the Internet into the latest avenue for terrorism. Terrorists are now harnessing the power of the Internet to wreak havoc among the public (Conway, 2002). Terrorists use the Internet mainly as a propaganda tool – it is a venue wherein they publicize their cause or explain their ideological justification without misinterpretation or censorship. As of 2002, a majority of the 33 groups deemed foreign terrorist organizations by the United States State Department had their own web sites. There are also many other websites, that, despite not being related to any terrorist group, provide information on how to commit terrorist activities such as bomb-making. The latter often escape criminal prosecution due to the First Amendment, which guarantees freedom of speech to the general populace (Conway, 2002). The very idea of cyber-terrorism, however, is not without contention. For one, it is still not clear as to what differentiates cyber-terrorism from freedom of expression. Also, there are certain Internet-related crimes that cannot be considered as cyber-terrorism, although they inflict damage upon the public. Indeed, terrorism in itself is already a notoriously difficult concept to define. The addition of computers to it further complicates the idea (Conway, 2002). The Internet: A New Weapon The Internet was originally intended as a means of resuming contact in the event of a nuclear attack. But due to its speed and convenience, it is currently a major venue for information, communication and commerce. As of September 2006, there were more than 1 billion Internet users worldwide (Vatis, 2006). With just one click of a mouse, an entrepreneur in Germany can deposit funds to a bank account in Switzerland and talk to a London-based cousin face to face through a web camera. A student in California, meanwhile, can learn everything about the Great Wall of China with merely a few keystrokes. After 9/11 It was only after 9/11 that the very concept of cyber-terrorism was actually developed. Before 9/11, Internet-related crimes were usually in the form of sending pornographic email to minors, defacing web pages, stealing credit card information and launching computer viruses (Conway, 2002). After 9/11, however, US officials realized that terrorist organizations could use the Internet to generate more bloodshed (Weimann, 2004). Al-Qaeda, for instance, could launch missiles or biological weapons to the US by simply pressing the â€Å"Enter† button of a laptop (Stohl, 2006). To a certain extent, the fears of the US were well-founded. In November 2000, an electronic attack was carried out from Pakistan against the Washington-based pro-Israeli lobbying group American Israel Public Affairs Committee (AIPAC). Aside from defacing AIPAC’s site with anti-Israeli commentaries, the attacker likewise stole some 3,500 email addresses and 700 credit card numbers, sent anti-Israeli diatribes to the addresses and published the credit card data on the Internet. The Pakistani hacker, known by the alias â€Å"Dr. Nuker,† claimed responsibility for the incident. It turned out that â€Å"Dr. Hacker† was a founder of the Pakistani Hackerz Club, an organization whose objective was to â€Å"hack for the injustice going around the globe, especially with (sic) Muslims† (Conway, 2002). The aforementioned cyber assault was not without precedent. The Lebanese Shiite Islamic group Hezbollah established its collection of web sites in 1995. At present, the group has three websites that can be viewed in either English or Arabic – one for its press office, another to describe its attacks on Israeli targets (http://www. moqawama. tv) and a third, Al-Manar TV, for news and information (http://www. manartv. com). These websites regularly provide the latest information about Hezbollah, including press statements, political declarations, photos, video and audio clips. An email address is also provided as contact information (Conway, 2002). After 9/11, as a result, federal agents issued subpoenas and search warrants to almost every major Internet-based company, including America Online, MSN, Yahoo! and Google. In addition, many web sites were subjected to official closure by the Federal Bureau of Investigation (FBI). Included among those that were closed down were radical Internet radio shows such as â€Å"IRA Radio,† â€Å"Al Lewis Live† and â€Å"Our Americas. † The â€Å"jihad web ring,† a collection of 55 jihad-related websites, lost dozens of its sites due to pullouts by Yahoo! Lycos Europe, meanwhile, created a 20-person team to filter its websites for illegal activity and terrorist-related content (Conway, 2002). Cyber-terrorism: Is There Really Such Thing? One of the most common arguments against cyber-terrorism is that it is an imaginary threat (Lacey, 2007). Contrary to popular perception, there is a minimal chance that cyber-terrorists would exact harm on innocent people by attacking corporate and governmental computer networks. As of this moment, terrorist organizations use the Internet only for fundraising, communications and propaganda. There is the possibility that terrorists might use computers as weaponry to a significant degree, but this will â€Å"probably happen in the (distant) future† (Conway, 2002). At present, terrorists would draw more attention to their cause by setting off bombs instead of hacking bytes (Conway, 2002). Instead of getting extremely paranoid about cyber-terrorism, the government should instead focus on eliminating cyber attacks against companies. As of July 2002, hackers had successfully launched at least 180,000 Internet attacks against more than 400 public, private, governmental and non-profit organizations. The brunt of these attacks fell on the power and energy industries, as well as on the technology and financial services. If left unchecked, these cyber attacks would be very detrimental to consumers – in order to make up for their losses to hackers, owners of the above-mentioned industries will have to raise the prices of their products and services (Fishman, Jospehberg, Linn, Pollack, Victoriano, 2002). Conclusion Paranoia over cyber-terrorism is very dangerous. Aside from diverting attention from more serious crimes such as cyber attacks, it violates civil rights and liberties. Under the guise of â€Å"fighting terrorism,† even websites whose only crime was to express radical ideas were closed down. While it is the duty of the state to safeguard its constituents from danger, doing so should not infringe their inalienable rights. It is true that terrorism might turn to cyberspace in the future in order to spread even more fear and bloodshed. But before the government rushes out to eliminate â€Å"cyber-terrorists,† it must first have a clear-cut concept of what constitutes cyber-terrorism and what makes a cyber-terrorist. Otherwise, the government will end up worse than the terrorists that it aims to get rid of. References Conway, M. (2002). What is Cyberterrorism? Current History, 101, 436-442. Retrieved October 17, 2008 from Academic Research Library. Fishman, R. M. , Josephberg, K. , Linn, J. , Pollack, J. , & Victoriano, J. (2002). Threat of International Cyberterrorism on the Rise. Intellectual Property & Technology Law Journal, 14, 23. Retrieved October 17, 2008, from ABI/INFORM Global. Lacey, D. ComputerWeekly. com. (2007, April 29). How Real is the Threat of Cyber Terrorism? Retrieved October 17, 2008, from http://www. computerweekly. com/blogs/david_lacey/2007/04/ how_real_is_the_threat_of_cybe. html Stohl, M. (2006). Cyber Terrorism: A Clear and Present Danger, the Sum of All Fears, Breaking Point or Patriot Games? Crime Law Soc Change, 46, 223-238. Retrieved October 17, 2008 from SpringerLink. Vatis, M. (2006). The Next Battlefield: The Reality of Virtual Threats. Harvard International Review, 28, 56-61. Retrieved October 17, 2008 from ABI/INFORM Global. Weimann, G. United States Institute of Peace. (2004, December). Cyberterrorism: How Real Is the Threat? Retrieved October 17, 2008, from http://www. usip. org/pubs/specialreports/sr119. html#threat

Jig and Fixture Design

Abstract This paper proposes a design of jigs and fixtures for the mass production manufacturing of Sportsman Race Series aluminum slipper pistons (Probe Industries) that are used in the Chevrolet LS Series V8 engines. The designs of two sets of jig and fixture designs are proposed. The first set (two vee-blocks and a drill bushing) is designed for the process of drilling the wrist pin holes in the piston. The second design (two vee-blocks and a pin locator) is used in the milling of the skirts and lower form of the piston.The designs use principles of manufacturing facilities design, research on manufacturing practices and 3D modeling software (Catia) in order to optimize quality (accuracy), costs and productivity in the manufacture of such pistons. 1. Introduction 1. 1 The Piston An important mechanical component of an internal combustion engine, the piston is basically a solid part in an airtight cylinder that moves under the pressure of a fluid and transfers the force of the expa nding gas to a crankshaft through a connecting rod (The American Heritage, 2005). Pistons typically consist of a few main features.Pistons are cylindrical. The top part of the piston that comes into contact with the expanding gas is the crown. All pistons have a wrist pin hole to contain a steel wrist pin that attaches the piston to a rod that is connected to the crankshaft. The skirt of the piston is the end opposite the crown and is often milled in the sides to reduce weight. 1. 2 Selected Component (Chevrolet LS Series V8 Piston) The specific component chosen for the design project is the Sportsman Race Series aluminum slipper piston (Probe Industries) used in the Chevrolet LS Series V8 engine.The high-speed nature of a V8 engine requires pistons to have reduced weight to improve engine balancing. Unlike older pistons that were made with cast iron, this piston is made with forged aluminum alloy to reduce its weight as well as improve fatigue life. Furthermore, this specific pisto n is a slipper piston with a length of only half its diameter and has some parts milled off in order to reduce size and weight dramatically. 1. 3 Objectives, Scope, and Assumptions The aim of this design project is to design jigs and fixtures for the mass production of the aluminum slipper piston used in the Chevrolet LS Series V8 engine.The scope of the design project is limited to designing jigs and fixtures for the only two processes in the manufacture of such pistons that require jigs and fixtures, specifically the drilling of the wrist pin holes and the milling of the skirts and lower form of the piston. The design project does not account for the exact design, accuracy or efficiency of the drilling and milling machines. The strength and hardness of the materials are not considered. The time and motion in between the processes are not measured for optimization. 2. Manufacturing the Component 2. 1 Component DesignThe exact specifications and design of the piston for the Chevrole t LS Series V8 engine were taken from a manufacturer of such pistons, Probe Industries. The bore (diameter) of the piston is 4 inches and the height is 2 inches. The wrist pin hole is 0. 927 inches in diameter and centered at 1. 155 inches below the crown. The wrist pin length is 2. 5 inches, meaning that the skirt below the oil grooves is milled at each end of the wrist pin hole up to 1. 25 inches away from the center of the cylinder (Probe Industries, 2012). These dimensions are important in the milling and drilling processes in the manufacture of the piston.The image below shows the rest of the dimensions and the tolerances (calculations shown later). 2. 2 Machining Processes in Manufacture of Component After forging a solid aluminum slug into the basic shape of the piston with the desired strength and stability, the component undergoes several machining processes. The first machining process involves using a lathe or a CNC turning machine to make the base, cut out oil rings or g rooves, and drill oil holes. The second process is to drill a large hole on one side of the piston through to the other. This (wrist pin hole) is where the wrist pin is placed to attach the piston to the connecting rod.The third process is to use a milling machine to shave off material at the sides where the wrist pin hole was drilled in order to reduce the weight of the piston. The fourth machining process involves finishing with a lathe machine, wherein the crown is made into its final shape, the bottom edges of the skirt are shaped, and slots/engravings are made. 3. 3 Machining Processes Requiring Jigs and Fixtures The only processes that require jigs and fixtures are the second and third machining processes, the drilling process and milling process. The first and the fourth process use CNC turning/lathe machines and they require no jigs or fixtures.The process of drilling the wrist pin hole however requires a bushing to locate the point in the cylinder that needs to be drilled a s well as a lower vee-block (with a locator at on end) and an upper vee-block (with the bushing and a pin/screw connecting to the lower vee-block) to hold the cylinder. The process of milling requires a lower vee-block as well but with a pin that goes through the wrist pin hole to hold the piston in place in the vee-block. A second, upper vee-block is used to guide the milling machine. The upper and the lower vee-block are referenced to each other with pins. 3.Functional Analysis of Jigs and Fixtures 3. 1 Drilling Process For the drilling process, a vee-block fixture is required to hold and support the cylindrical component. The design of the vee-block includes a locator at the end of the cylinder to keep the piece from moving and to help put the cylinder/piston in the right position. To drill the hole, a bushing is required to guide the drilling machine. The bushing goes through an upside-down vee-block that is put in location by pins connecting it to the lower vee-block. Bushing f or Jig Assembly: Vee-Block for Jig Assembly: Drilling Jig Assembly:Drilling Fixture Assembly (Vee-Block): Drilling Process Jig and Fixture Assembly: 3. 2 Milling Process For the milling process, the piston must be held in the right position and orientation. A vee-block is again used to support the cylindrical piston. And a locating pin is placed in the center of the vee-block at an exact location along it in order to put the piston in the right position along the vee-block and at the right orientation (hole facing upwards) for the milling to be correct (since only the sides with the holes must be milled and only exactly below the oil rings).A thin upside-down vee-block is strapped on to the top of the cylinder and connected to the lower vee-block at an exact location (using pins or screws) in order to hold the piston in place and to keep the milling machine from milling into the oil rings. To mill the other side, the piston is simply turned over and fitted into the locator from the newly milled side. Milling Process Jig (Vee-Block): Milling Process Fixture (Vee-Block and Locating Pin): Milling Process Jig and Fixture Assembly: 4. Tolerance Calculation 4. 1 Tolerance Calculation of Jig and Fixture for Drilling Process To compute or the tolerance of the upper jig of the drilling process, the tolerances of the left and right locating pins and pin holes are computed first. The tolerances and the clearances must be just enough so that both locating pins can fit in the pin holes (in all cases including largest and smallest size of one or both pins and of one or both holes). It should be noted that the worst possible scenario is that on one side of the jig, the hole is the maximum size and the pin is the minimum size while on the other side, the hole is the minimum size and the pin is the maximum size. Given that the diameter of each pin hole in the jig is 12. mm (or 0. 5 inches); the tolerance chosen for this is plus/minus 0. 01 mm (leading to a range of 12. 69-12. 71 mm for the diameter of the hole). A clearance of 0. 05 mm is chosen, causing the largest diameter for the locating pin to be 12. 64 mm. The tolerance chosen for the locating pin is plus/minus 0. 005 mm (leading to a range of 12. 635-12. 645 mm for the diameter of the pin). In the worst case scenario, on one side, the maximum hole size would be 12. 71 mm while the minimum pin size would be 12. 635 mm (leading to a potential gap of 0. 075 mm and a left or right shift of 0. 0375 mm).In the worst case scenario for locating pins where one side has a maximum hole of 12. 71 mm and a minimum pin of 12. 635 mm and the other side of the jig has a minimum hole of 12. 69 mm and a maximum pin of 12. 645 mm, the maximum shift of 0. 0375 mm on either side would still allow the larger pin to fit in the smaller hole since there would still be a gap of 0. 0075 mm (12. 69 – 0. 0375 – 12. 645 = 0. 0075). Since the bushing is screwed on tight into the jig, there is no clearance between the bushing and the jig and thus no need to differentiate between the two pieces in terms of tolerance.The tolerances of the pins and pin holes would cause variation in the position of the drill. The worst case scenario would be if on any side, the pin hole is of maximum size (12. 71 mm) and the locating pin is of minimum diameter (12. 635 mm) leading to a potential gap of 0. 075 mm and a left or right shift of 0. 0375 mm. This shift would cause the drill (center of bushing hole) to move 0. 0375 mm in any direction from the center of the jig, and thus the final wrist pin hole would be plus/minus 0. 0375 mm from the center of the final product (50. 7625 – 50. 8375 mm from the side of the piston and 29. 025 – 29. 3775 mm from the top of the piston). This is within the product specification wherein the tolerance is plus/minus 0. 05 mm (50. 75 – 50. 85 mm from the side of the piston and 29. 29 – 29. 39 mm from the top of the piston). The positions of the loca ting pins and pin holes for the upper and lower vee-block have a tolerance of 0. 005 mm on any direction and thus cause the position of the drilled hole to be between 29. 335-29. 345 mm from the top of the piston and between 50. 795-50. 805 mm from the side of the piston (still within product specifications).The locator on the lower fixture as well as the back plate each has a tolerance of 0. 005 mm combining into a worst case shift of 0. 01 mm and would cause the position of the drill to be between 29. 33-29. 35 mm from the top of the piston (still within product specifications). All the other tolerances of the drilling assembly have no effect. 4. 2 Tolerance Calculation of Jig and Fixture for Milling Process For the milling process, the holes in the upper and lower vee-blocks for the pins that locate the upper vee-block are exactly the same as in the upper jig for the drilling process.Thus the tolerances are the same (0. 01 mm hole tolerance, 0. 05 mm clearance, and 0. 005 mm loca ting pin tolerance) and so is the worst case scenario (shift of 0. 0375 mm). Since the upper vee-block guides the milling machine with a feeler gauge of 0. 01 mm, the worst case scenario would mean that the milled section is either 0. 0375 mm too high or too low on the piston (16. 7625 – 16. 8375 mm from the top of the piston). This is within the product specification wherein the tolerance is plus/minus 0. 05 mm (16. 75 – 16. 85 mm from the top of the piston).As of the lower fixture for the milling process, the symmetrical vee-block allows the cylindrical component to remain centered without rolling even when the size of the component or the fixture varies, thus eliminating the need to set tolerances. However, the tolerance must be calculated for the locating pin that goes through the wrist pin hole since a gap here would cause milling area to move up or down from the top of the piston. The hole that was previously drilled with a diameter of 23. 55 mm is assumed to hav e a tolerance of 0. 01 mm from the drilling process.A clearance of 0. 05 mm is chosen. And the locating pin has a tolerance of 0. 005 mm, thus ranging in size from 23. 49 – 23. 5 mm. In the worst case scenario of a hole with a maximum of 23. 56 mm and a locating pin with a minimum of 23. 49 mm, the potential gap would be 0. 07 mm or a shift of 0. 035 mm up or down the cylinder. This would lead the milling machine to start milling at a point between 16. 765 – 16. 835 mm from the top of the piston. This is within product specification wherein the tolerance is plus/minus 0. 05 mm (16. 75 – 16. 85 mm from the top of the piston).The locations of all the holes and locating pins should have a tolerance of 0. 005 on any direction in order to keep within product specifications. 5. Clamp Selection and Force Calculation For the drilling process, strap clamps are applied on the fixture by using a pair of socket head cap screws on the two sides of the upside-down vee-block. The two socket head cap screws locate the upper vee-block and clamp it to the lower vee-block when holding the work piece piston in place. The diameter of the holes on lower vee-block for screw is 12. 7 mm, thus M12 size socket head cap screws are selected for clamping.The tool force direction of drilling is downward and it has a tool rotation. The strap clamps fasten the upside-down vee-block and the lower vee-block preventing the cylinder from rotational motion and horizontal motion. The tool force can be taken advantage of clamping down the work piece cylinder. According to Spaenaur (2012), the tightening torque of a screw is the product of torque-friction coefficient, nominal screw diameter, and clamping load (T = KDP). The Table 1 has shown that the M12 socket head cap screw has a minimum tensile strength of 160000 pound per inch, and its material is High Carbon Quenched Tempered.In addition, it has a production torque of 125 pound. feet.. Then search this torque data in the re lated Table 2, the clamping force is approximately 13395 pound. For the milling process, the strap clamps are applied by a pair of socket set screws on the two sides of the thin upside-down vee-block. The two socket set screws locate the upper vee-block and clamp it to the lower vee-block when holding the work piece piston in place. The diameter of the holes on lower vee-block for screw is 12. 7 mm, thus M12 size socket set screws are selected for clamping.The table 1 has shown that M12 socket set screw has a minimum tensile strength of 212000 pound per inch, and its material is also High Carbon Quenched Tempered. It has a production torque of 43 pound. feet.. It can be seen in the related table, the clamping force is approximately 4286 pound. For a drilling machine, Pirtini and Lazoglu (2005) has proved that the pressure over the work piece as the cutter moving down into the work piece with same federate remains a constant value, and additional tests have been suggested that the co nstant pressure P(f) (MPa) can be described as a function of feed rate (f) (mm/min).P (f) = 1. 5364f – 103. 06. If the feed rate of the drilling machine is 198 mm/min, then the pressure is 201. 14 MPa. The equation to calculating cutting force is F= P * A. where F is the net force between the measured force and predicted thrust force due to cutting in the thrust direction and A is the contacting area of the cutter at an instant. The force is about 87 kN with the 23. 55 mm diameter drilling hole. For milling machine, we take the piston as an example: Width of cut = 79. 3mm = 3. 122 inch Depth of cut = 19 mm = 0. 748 inch Feed rate = 19. 5 inch/min K† factor =1. 56 MRR = depth of cut x width of cut x feed rate MRR = 3. 122 x 0. 748 x 19. 5 = 45. 54 inch? /min A formula for calculating horsepower (HPC) of the milling cutter is HPC = MRR/K HPC = 45. 54 / 1. 56 = 29. 19 hp The formulas above are from the article ‘A New Milling 101: Milling Forces and Formulas’ ( Brian Hamil, 2011). One metric horsepower can be defined as the power to raise a mass of 75 kilograms against the earth's gravitational force over a distance of one meter in one second. It can be calculated that the tool force is about 21 kN. . Cost Calculation Operation| Part| Rough Volume (m? )| Drilling| Lower vee-block| 0. 00095| | Upper upside-down vee-block| 0. 00051| Milling| Lower vee-block| 0. 00082| | Thin upside-down vee-block| 0. 00023| Total Volume| | 0. 00251| Density = 7225 kg/m? Mass = 18. 13 kg = 39. 97 pound Iron Materials| Casting process| Cast iron cost (USD/lb) without machining| Machining cost(USD/lb)| Gray iron| Green sand| 0. 58 to 0. 61| 0. 07 to 0. 14| | Resin sand| 0. 65 to 0. 69| 0. 07 to 0. 14| | Shell molding| 0. 72 to 0. 76| 0. 07 to 0. 14|Ductile iron| Green sand| 0. 64 to 0. 67| 0. 07 to 0. 14| | Resin sand| 0. 71 to 0. 74| 0. 07 to 0. 14| | Shell molding| 0. 75 to 0. 79| 0. 07 to 0. 14| Gray iron with shell molding machining process is selected for the fixture. Then the total cost for the 4 vee-blocks can be calculated: (0. 74 + 0. 10) x 39. 97 = 35. 57 USD = 32. 81 AUD Items| Description| Quantity| Total Cost (AUD)| Vee-block| –| 4| 32. 81| Socket head cap screw| M12 x 60 High Tensile| 2| 5. 49| Socket set screw| M12 X 60 Grade 14. 9| 2| 3. 13| Bushing| 79 Honda CBX Bronze Swing Arm| 1| 22. 4| Locating pin| 23. 5 mm diameter| 1| 18. 87| Total Cost| | | 83. 24| Thus the total cost for our design is approximately 83. 24 AUD. It should be noted that the selling price of the final product ranges between 100-200 AUD. 7. Conclusion It can thus be concluded that in the manufacture of Sportsman Race Series aluminum slipper pistons (Probe Industries) for Chevrolet LS Series V8 engines, jig and fixture assemblies can be used for the two machining processes (drilling the wrist pin hole and milling the bottom form of the piston).The jigs and fixtures designed were basically assemblies of Vee-Blocks with a bushing for the drilling process and another assembly with a locating pin through the wrist pin hole for the milling process. The tolerances were designed in order to not exceed the tolerances in the product specifications. The clamp forces were found to be sufficient and the cost of the jig and fixture is very small compared to the profit made from the final product. The design furthermore is very simple and is thus easily modified to be integrated in a fast-moving assembly line. Therefore it can be concluded that the jig and fixture designs are appropriate. . References Hamil, B. (2011) ‘A New Milling 101: Milling Forces and Formulas’ http://www. mmsonline. com/articles/a-new-milling-101-milling-forces-and-formulas. Pirtini, M. & Lazoglu, I. (2005) Forces and hole quality in drilling International Journal of Machine Tools & Manufacture 45 (2005) 1271–1281. Spaenaur (2012) ‘Suggested Tightening Torque1 Values to Produce Corresponding Bolt Clamping Loads’. http://www. spaena ur. com/pdf/sectionD/D48. pdf 9. Appendix Table 1 http://www. torqwrench. com/Info/fasteners. php Table 2 http://www. torqwrench. com/Info/fasteners. php

Plate Tectonics Theory Essay

‘Evaluate how plate tectonics theory helps our understanding of the distribution of seismic and volcanic events’ In 1912, Alfred Wegener published his theory that a single super continent named Pangaea once existed about 300 million years ago. He proposed that Pangaea then later split into two continents of Laurasia in the north and Gondwanaland in the south and that today’s continents were the result of further splitting of these two land masses. Where the plates split are known as plate boundaries. Wegener’s theory of continental drift was supported by both geological and biological evidence that these areas were once joined. The geological evidence included the rock sequences in Northern Scotland closely agreeing with those found in East Canada, indicating that they were laid down under the same conditions in one location as well as the obvious jig saw fitting appearance of today’s continents, in particular, the bulge of south America fitting into the indent below west Africa. The biological evidence comprised of fossil findings linking different continents. Fossil brachiopods found in Indian limestones were comparable with similar fossils in Australia and the fossil remains of Mesosaurus’ were found in both South America and southern Africa. It is unlikely that the same reptile could have developed in both areas or that it could have migrated across the Atlantic. Despite the evidence, Wegener’s theory was unable to explain how continental movement had occurred. However from the 1940’s additional evidence accumulated after the discovery of the mid-Atlantic ridge and huge oceanic trenches. Examination of the ocean crust either side of the mid-Atlantic ridge suggested that sea-floor spreading was occurring. Magnetic surveys of the ocean floor in the 1950’s, showed regular patterns of paleomagnetic striping surrounding the ridges. It was discovered that when lava erupts on the ocean floor, magnetic domains within iron rich minerals in the lava are aligned with the magnetic field of the earth. This fixes as the lava cools and records the earths polarity at the time of their cooling. As the polarity of the earth reverses every 400,000 years, bands of normal and reversed polarity rocks are mirrored on either side of the mid ocean ridges, suggesting that new rocks are being added equally on either side. Surveys also established the age of the rocks and found young ages for places on or near the ridges and much older ages for rock nearer to the continental masses, demonstrating that older crust is continually being pushed aside by  new crust. The discovery of sea floor spreading led to the assumption that the earth must be getting bigger however this was not the case and the discovery of oceanic trenches allowed for the conclusion that plates must be being destroyed at different boundaries to accommodate the increase in their size at mid-oceanic ridges. Hot spots around the core of the earth generate thermal convection currents within the mantle which cause magma to rise towards the crust and then spread before cooling and sinking. This circulation of magma is the driving force of plate movement. This movement has an effect on all the plates determining their type of boundary each with their own features and resulting volcanic and seismic events. Divergent boundaries occur along spreading centers where plates are moving apart and new crust is created by magma pushing up from the mantle resulting in oceanic ridges and rift valleys. Where two oceanic plates are moving apart they produce mid oceanic ridges with their form influenced by the rate at which the plates separate. Volcanic activity occurs along the ridge forming submarine volcanoes which sometimes rise above sea level accommodating fairly gentle sides and frequently gentle eruptions. An example of this is located in Surtsey, to the south of Iceland, and Iceland itself. As new crust forms and spreads, transform faults occur at right angles to the plate boundary due to shearing pressure. The parts of the spreading plates on either side of these fault lines may move at different rates causing shallow focus earthquakes. Where two continental plates are spreading they produce rift valleys. The brittle crust fractures at sections as it moves apart causing a normal fault where hanging wall falls down relative to the foot wall due to tensional stress. A feature of a rift valley is known as a ‘graben’ which forms when a block of rock falls between two faults and creates the valley floor and also a ‘horst’ which is formed when a block of rock is pushed up between two faults. This area is associated with volcanic activity as the crust is much thinner than in neighbouring areas. Convergent plate boundaries occur when two plates are moving towards each other. Where oceanic and continental crusts meet, the denser oceanic crust is forced under the lighter continental plate known as subduction. The down warping of the oceanic plate forms a very deep ocean trench and the continental plate edge is affected by the reverse fault lines that cause folding of the plate to produce uplifted rock that forms Fold Mountains. As  the oceanic crust descends, the inc rease in pressure can trigger major earthquakes along the line of the sub ducting plate. As it descends further the surroundings become hotter and additional heat from the friction causes the rock to melt in the benioff zone which begins to rise as plutons of magma. When they reach the surface they form composite explosive volcanoes. Eruptions can also occur offshore producing volcanic islands referred to as island arcs. Where two types of the same plate meet they create collision zones by which the compression of the two plates results in the folding of the plate to form Fold Mountains. As there is little subduction, there is no volcanic activity however the movement of plates can trigger shallow-focus earthquakes. Conservative plate boundaries occur when two crustal plates slide past each other and the movement of the plates is parallel to the plate boundary. The movement of the plates creates stresses between the plate edges and as they rub past each other the release of friction triggers shallow focus earthquakes. However as there is no subduction, there is no volcanic activity. The best known example of a conservative boundary is the San Andreas Fault in California, where the pacific and North American plates move parallel to each other. Volcanic activity that does not occur along any plate boundary can be the result of many a fault lines and hot spots beneath the crust. Alfred Wegener’s theory allowed us to gain insight into the potential creation of our tectonic plates and their boundaries. The evidence provided by wegener’s theory and the record of paleo-magnetism upon the ocean floor supported the idea that the tectonic plates are moving. Supported by the theory of convection currents, the movement of these plates helps our understanding of the distribution of seismic and volcanic events by allowing us to identify varying plate boundaries that create different features and as a result cause these events. This explains their distribution, as events such as these are located in areas above plate boundaries, apart from the odd one which can occur above many a fault lines or hot spots caused by the movement of plates.

Generational Poverty

Generational poverty is an unfortunate issue which affects individuals, families, and cultures all over the world. Generational poverty is considered a very complex problem due to the length of time and ways it affects certain families as an entirety. The severity of this issue makes it extremely difficult to find any resolutions in improving this epidemic. If a family is experiencing generational poverty, they have had to live in poverty for a minimum of two generations.According to Cleveland, â€Å"It is important to recognize this time factor to be able to separate it from â€Å"situational poverty,† characteristically understood as a lack of resources due to particular sets of events, i. e. a death, chronic illness, divorce, etc. ,† (n. d. ). Almost every family and individual decision is made for the present. Individuals are not taught to think ahead and plan for their future. This is a trending factor in the difficulty in overcoming generational poverty.Members wh om belong to generational poverty have a sense of entitlement from society. Individuals have a constant defense mechanism to society as a whole. The most significant aspect to families suffering from generational poverty is that the â€Å"momma† is the central figure and focus to the family. The mom is what feels safe to the family. She is the ultimate caregiver to individuals in her family and to her house. Even after her children have grown into adults, both the mother and children have a difficult time with the child becoming independent.Love is the center of â€Å"momma’s† home. The male figure in generational poverty is responsible for the manual labor and will fight for their family. Although they display a rough outer layer, they still show a great love for the members in their family. Even though there is a constant, huge amount of love, most communication within the family maintains in a nonverbal form. Overcoming generational poverty can be a challengi ng task. There are several key factors when considering on improving the poverty status.Some of these factors include: Education is key in getting out and staying out of generational poverty, being in poverty is rarely about a lack of intelligence or ability, individuals stay in poverty because they do not see â€Å"choice†, or if they do, they do not know how to access proper resources or people to get them to the point of actually â€Å"choosing† to organize themselves, complete assignments, behave respectfully, plan for the future, and communicate in conventional register (Cleveland, n.d. ).Once a child is born into generational poverty, schools are one of the few places where they are exposed to certain choices and rules of how a higher class lives. This also allows the child access to resources and people who want to assist in the child rising from poverty. There are specific characteristics displayed in those suffering from generational poverty, which contribute to the difficulty in overcoming it. One of these characteristics is the â€Å"working memory†.â€Å"Neuroscientists discovered that the working memories of children raised in poverty are much smaller compared to those in middle-class,† (Pinoy, 2009). An individual’s brain capacity is a crucial part of their development. If a child is raised in a stressful household, the stress causes a limited supply of new nerve cells in the brain and memory. This can make it very difficult for the child to solve problems, read and properly communicate. The most effective way to begin overcoming generational poverty is for society to have a clear understanding of the complexity of this issue.Women face many unique challenges in the different stages of poverty life. Although, many issues that trap women and girls in generational poverty can be alleviated by a good education. Job prospects multiply with every level of school completed; better jobs bring more income and, consequen tly, more options for housing, transportation, child-care and healthcare. But, it is challenging for a woman to secure a good education due to the several setbacks. A woman in poverty does to have the ability or access to pay for necessary education for either her or her child(ren).A woman in poverty is consumed with the hours she spends working to care for the home and kids and feels this is the number one priority. It is also normal for the women to not have access to reliable transportation. According to Knight, â€Å"For a girl who seems to be making her way up the ladder out of generational poverty, pregnancy can be an enormous setback,† (2012). Mental health is even more likely to be neglected. The research shows that starting early by teaching girls life skills, such as financial  planning and goal setting, can reduce stress and increase self-esteem.Girls who live with hope and support are more likely to feel that they have inherent value and don’t have to dep end on others – including boys – for validation. In order to improve the challenges that women in poverty face, it is imperative for society to offer programs and convenience to teach these women on how to improve their life quality. Mentors should be available to provide services on sharing examples and how positive goals can be accomplished by taking the necessary steps.I have learned a great deal of information after viewing the informational videos and reading all the material on generational poverty. It has definitely changed my perspective on how I approach this special population. As most of the general population, stereotyping is a part of my daily life. I never truly understood the depth of the generational poverty issues that are present. I have learned that not only is there a lack of school environment education, but individuals suffering from generational poverty need educated on how to â€Å"properly† live life each day in order to obtain goals.I h ave also learned these families can love more than your average family. They have a very strong bond between the members within their family. While love is important and necessary, they also have a misperception of life goals. The implications of this destructive cycle are the reasons generational poverty continues to be an issue. It not only affects individuals, it affects the family structure for many generations. Society as a whole needs to determine more effective ways to break it.