Hindenburg Essay Example

Hindenburg Essay Thesis: The Hindenburg has contributedto the history of aircraft as well as A. attention getter and relate it to Hindenburg A. Count von Zeppelinsfirst rigid airships III. Paul von Hindenburg: The man that the famous airship was named after. A. Hindenburg, king of rigid airships and the last of them. B. aircraft has changed because of it C. investigations have changed because of it. the hindenburgs history and investigation A 747, O.J. Simpson, the Goodyear blimp and the shooting at Columbine High School all have one thing in common.The Hindenburg has contributed to these things in one way or another.The 747 is a modern aircraft that is very popular in commercial airlines.O.J. Simpson is a man that was charged with the murder of two humans; he was proven not guilty in one court and guilty in another.The shooting at Columbine High School was an occurrence, just over a month ago, in which two students destroyed their high school while killing 15 people.Have you found the connecti on yet?As you read on, the connection will be clear.The Hindenburg has contributed to the history of aircraft as well as The rigid airship took no time to develop into useful source of transportation (Hindenburg video 1).Count Von Zeppelin was thefirst to create rigid airships (video 1).His idea was to fill many airbags with hydrogen, enclose them in an aerodynamic rigid structure and have onboard engines (video 1).He built the LZ1 and flew it, July 2, 1900, two years before the Wright Brothersfirst flight (video 1).The Zeppelin company began developing and expanding (video 1).They offered sight seeing tours, but were however, very expensive (video 1). By 1914, the Zeppelins had carried over 10,000 people over 100,000 miles (video 1).All along the success, the Zeppelins were soon used for a military purpose (video 1).In 1928 the Graf Zeppe

A Perfect Day for Bananafish essays

A Perfect Day for Bananafish essays Comparison Between A Perfect Day for Bananafish and For Esme With Love and Squalor J D Salinger wrote Nine Stories with the same brilliance as Catcher In The Rye. His style is so unique and complex that all of his short stories are truly enjoyable. Two of those stories are A Perfect Day for Bananafish and For Esme With Love and Squalor. The main characters in both of these stories, Seymour and Sergeant X, have served in World War II, and the fighting has taken its toll on them. Their physiological well-being was sacrificed and as a result they are no longer the same people they were before. Both feel alienated from the people in their life, the same people they had loved before the war. The isolation the war has caused is carried over into their lives, and it caused these men to search for new forms of comfort and security, in the respective forms of Sybil and Esme. In A Perfect Day for Bananafish, Muriel and her husband Seymour have different perspectives of life. Muriel is a carefree and complacent person, while her husband is quite strange and slightly paranoid. His paranoia is illustrated when he looses it in the hotel elevator, I have two normal feet and I cant see the slightest God-damned reason anyone should stare at them. Muriel, however, is unacquainted with Seymours wild breakdowns. She is rather confident that Seymour is perfectly sane as she reports to her mother on the telephone. Muriel doesnt know about this side of Seymour because he has become alienated from her after the war. Their personalities dont match anymore, if they ever did, and he is seeking some sort of understanding that he knows Muriel cannot provide. Seymours relationship with Sybil is making up for Muriels shortcomings. Seymour is looking for the understanding of a child and the love of an adult. He wants someone who will not judge him. He realizes the impossibil ity of his desires with Sybil when he ge...

Specific public policy case in USA during the government shutdown Essay

Specific public policy case in USA during the government shutdown - Essay Example The issue of national security in the United States is one of the most sensitive issues. After the Twin towers were attacked in 2001 security policies were given priority over other policies during appropriation of funds by the legislature (Campbell, 2008). However, as the national security stabilizes and the country becomes more and more secure many proponents are of the opinion that the appropriation has now become too much in comparison with its contribution to the status of the national security (Klein, 2013). Some legislators, in the events leading to the government shutdown, were proposing a cut, while others were of the opinion that the move to cut on military expenditure will only prove costly in the long run. This paper will discuss the government shutdown of 2013 and then go ahead to explore the US security policies using several sociological and political theories to analyze the key themes of the policy and ponder on the future developments and the alternative course of ac tion. The paper will also employ the Eugene Bardach policy analysis model to bring out the contentious issues and their possible alternatives. The Bacchi model will also be integrated to problematize the issue and discuss the presumptions of the policies. The US Government Shutdown The United States of America operates under a federal system of government. This government offers a wide range of public services in the areas of health, education, social security, medical, insurance and the country’s security while the other services are offered by the individual states to the citizens. For it to offer these services, it needs funds, which are allocated to each of its department by the legislature. The last government shutdown took place in 2013 under the President Obama administration from October 1 to October 17 when a bill was signed. A shutdown of the federal government happens when there is no Appropriation bill that has been signed that allocates the various government dep artments to continue spending funds (Bill, 2013). These funds are allocated at the start of a fiscal year and when the year ends if there has not been any more appropriation from the Congress, and then the government has to shut down because of the funding gap that is created. The 2013 government shutdown took place because the Republicans, and the Democrats could not agree on the funding of the Patient Protection and Affordable Care Act, popularly known as Obamacare. This act was signed into law in 2010 but has created deep divisions in the House of Representatives and the Congress. The Republicans who are controlling the House of Representatives want to cut the spending, and the amount allocated to this policy whereas the Congress which is dominated by the Democrats did not support the cut. This confrontation led to the shutdown as the House of Representative passed a bill that had suggested a funding cut which was rejected by the Congress (Steinhauser, 2013). The main reason behi nd the Republicans proposing a cut in spending is because the government deficit in budget had already hit 15.7%, and the International Monetary Fund was already considering not lending the US government any more funds because of their rising debt levels; the credibility of borrowing was in question. During the 16-day shutdown, however, the Congress continued passing specific bills that addressed specific policies, which were then signed by

Madbury vs Madison and Mc Collough vs Maryland Essay

Madbury vs Madison and Mc Collough vs Maryland - Essay Example Marbury filed a suit before the Supreme Court on its original jurisdiction and prayed for a writ of Mandamus to be passed, ordering Madison to deliver him the signed commission (Levinson and Balkin 3). The questions or legal issues that were to be decided in this case were, whether the applicant had a right to the commission he demanded, whether the country can afford him a remedy and lastly, whether the remedy provided by the court will be in the form of Mandamus (William Marbury vs. James Madison). The case arose out of the dispute between two political parties, which were the Federalists, primarily led by Alexander Hamilton on the one hand and on the second hand the Republicans, led by Thomas Jefferson, James Madison and others (Levinson and Balkin 3). Jefferson and fellow Republicans were not pleased with the Federalists, who were trying to safeguard their political power by packing the court with their own men before they left their office. The Republicans vowed to fix the wrong which had been done by Republicans (Mountjoy & Mc Neese 27-28). This ultimately led to the battle in the form of Madbury vs. Madison in the US Supreme Court, Now coming to the case of Mc Culloch vs. Maryland, the parties to this suit were Mc Culloch who is the Appellant in this case, whereas, the State of Maryland is the defendant (Mc Culloch vs. Maryland). The State of Maryland had enacted a statute imposing a tax on all the banks, which were operating in Maryland and were not chartered by the state. The statute provided that all such banks will not have the power to issue note and can only issue them by purchasing the paper to be issued by the state (Mc Culloch vs. Maryland). The cashier of the Baltimore branch of the second bank of the United States, which was established by the 1816 Act of the Congress, issued bank notes without complying with the Maryland law. Maryland sued Mc Culloch to pay taxes and Mc Culloch contested the constitutionality of the Act (Mc Culloch vs. Maryla nd). The issues, in this case, were whether the Congress had the power to incorporate a bank, even when the power is not specifically stated by the constitution and whether the State of Maryland had the power to tax an institution created by its own power granted by the constitution (Mc Culloch vs. Maryland). The Supreme Court held in this case that the Congress had power under the Constitution to incorporate a bank, that the State of Maryland did not have the power to tax an institution created by the Congress pursuant to its powers under the constitution and the Act passed by Maryland to levy taxes was unconstitutional (Mc Culloch vs. Maryland). Despite the fact that the above two cases are distinct and stretched over two different time period, having different subject matter and facts, the two cases have certain things in common. Firstly, both the cases were on constitutional law and required interpretation of the constitution. Secondly, both cases were initiated in the same peri od of time, which is the early 19th century. Thirdly, both the cases had supreme importance and were landmark cases in the history of the United States, in the sense that both the cases decided important issues.

Technical Certificate unit worksheet Essay Example for Free

Technical Certificate unit worksheet Essay 1. Explain how a working relationship is different from a personal relationship (1.1.1) A working relationship is where you are placed with other people and work as part of a team, where each individual is working following professional codes of practise, towards the achievement of shared aims and objectives. You do not necessarily have to like the people you work with but you need to keep personal opinions and feelings to yourself. Mutual respect and understanding is a key factor in developing a good working relationship. A personal relationship is a relationship formed through choice, with someone you like, who you share interests and feelings with. In personal relationships there isn’t any set rules or procedures to follow and you are able to voice your opinions. 2. Describe different working relationships in health and social care settings (1.1.2) There are many different relationships in health and social care settings, these include relationships between careers and service users, careers and other health care professionals, such as GP’s and nurses, careers and service users families and between colleagues and managements. For each of these you will develop a different type of working relationship, but you should always remain professional. 3. Describe why it is important to adhere to the agreed scope of the job role (2.2.1) It’s important to adhere to agreed scope of your job role as you have agreed with your job description within your contract, so it’s your legal  obligation to work within it. By following your job role you are working alongside your company’s policies and procedures and giving the best quality of care you can. 4. Outline what is meant by agreed ways of working (2.2.2) Agreed ways of working means that all care workers should work in accordance with policies and procedures, roles and responsibilities within job descriptions which their employees have set out. 5. Explain the importance of full and up-to-date details of agreed ways of working (2.2.3) It’s important so that care homes or environments are run in accordance with legislations. So staff adhere to agreed standards and regulations at all times. It also means that service users will not be put at any risk. 6. Explain why it is important to work in partnership with others (3.3.1) It’s important to form professional relationships with team members, colleagues, other professionals as well as individuals and their families in order to promote effective communication and effective ways of sharing accurate information. It will help to give service users the best possible care as everyone will be clear on each service user’s needs, wishes and preferences 7. Identify ways of working that can help improve partnership working (3.3.2) We can improve partnership working through effective communication and information sharing. By working as a team and having regular staff meetings, with colleagues and other health care professionals. 8. Identify skills and approaches needed for resolving conflicts (3.3.3) You should try to handle conflict situations by remaining calm, ending the conflict before it escalates and remaining respectful of others. You should  try to demonstrate active listening and discuss the situation in a calm and rational manner to try and resolve the conflict. 9. Explain how and when to access support and advice about: (3.3.4) a.partnership working- you can get support and advise from other colleagues, your manager, supervisor or other external agencies such as CQC. b. resolving conflicts- it’s always worth trying to resolve conflict with the individual, but if you can’t then you should speak to your manager. Further issues can be address with HR who can offer you support on resolving conflict and may offer you mediation services to help you with this. Once you have completed, your Learning Advisor will be able to cross reference all knowledge into Unit 4222-206 of the diploma Patricia Whyte – LA- Qube Learning

Light Emitting Diode | Dissertation

Light Emitting Diode | Dissertation Introduction Alight-emitting diode(LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting. Introduced as a practical electronic component in 1962, early LEDs emitted low-intensity red light, but modern versions are available across thevisible, ultraviolet and infrared wavelengths, with very high brightness. When a light-emitting diodeis forward biased (switched on), electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is calledelectroluminescenceand thecolorof the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. An LED is often small in area (less than 1mm2), and integrated optical components may be used to shape its radiation pattern.LEDs present manyadvantagesover incandescent light sources includinglower energy consumption, longerlifetime, improved robustness, smaller size, faster switching, and greater durability and reliability. LEDs powerful enough for room lighting are relatively expensive and require more precise current andheat managementthan compactfluorescent lampsources of comparable output. Light-emitting diodes are used in applications as diverse as replacements foraviation lighting,automotive lighting(particularly brake lamps, turn signals and indicators) as well as intraffic signals. The compact size, the possibility of narrow bandwidth, switching speed, and extreme reliability of LEDs has allowed new text and video displays and sensors to be developed, while their high switching rates are also useful in advanced communications technology.InfraredLEDs are also used in theremote controlunits of many commercial products including televisions, DVD players, and other domestic appliances. History Discoveries and early devices Green electroluminescence from a point contact on a crystal ofSiCrecreatesH. J. Rounds original experiment from 1907. Electroluminescenceas a phenomenon was discovered in 1907 by the British experimenterH. J. RoundofMarconi Labs, using a crystal ofsilicon carbideand acats-whisker detector.RussianOleg Vladimirovich Losevreported on the creation of a first LED in 1927.His research was distributed in Russian, German and British scientific journals, but no practical use was made of the discovery for several decades. Rubin Braunstein of theRadio Corporation of Americareported on infrared emission fromgallium arsenide(GaAs) and other semiconductor alloys in 1955.Braunstein observed infrared emission generated by simple diode structures usinggallium antimonide(GaSb), GaAs,indium phosphide(InP), andsilicon-germanium(SiGe) alloys at room temperature and at 77kelvin. In 1961, American experimenters Robert Biard and Gary Pittman working atTexas Instruments,found that GaAs emitted infrared radiation when electric current was applied and received the patent for the infrared LED. The first practical visible-spectrum (red) LED was developed in 1962 byNick Holonyak Jr., while working atGeneral Electric Company.Holonyak is seen as the father of the light-emitting diode.M. George Craford,a former graduate student of Holonyak, invented the first yellow LED and improved the brightness of red and red-orange LEDs by a factor of ten in 1972. In 1976, T.P. Pearsall created the first high-brightness, high efficiency LEDs for optical fiber telecommunications by inventing new semiconductor materials specifically adapted to optical fiber transmission wavelengths. Until 1968, visible and infrared LEDs were extremely costly, on the order of US $200 per unit, and so had little practical use.TheMonsanto Companywas the first organization to mass-produce visible LEDs, using gallium arsenide phosphide in 1968 to produce red LEDs suitable for indicators. Hewlett Packard(HP) introduced LEDs in 1968, initially using GaAsP supplied by Monsanto. The technology proved to have major uses for alphanumeric displays and was integrated into HPs early handheld calculators. In the 1970s commercially successful LED devices at fewer than five cents each were produced by Fairchild Optoelectronics. These devices employed compound semiconductor chips fabricated with theplanar processinvented by Dr. Jean Hoerni atFairchild Semiconductor.The combination of planar processing for chip fabrication and innovative packaging methods enabled the team at Fairchild led by optoelectronics pioneer Thomas Brandt to achieve the needed cost reductions. These methods continue to be u sed by LED producers. History Of LEDs and LED Technology Light Emitting Diode (LED) Light Emitting Diode (LED) is essentially a PN junction semiconductor diode that emits a monochromatic (single color) light when operated in a forward biased direction. The basic structure of an LED consists of the die or light emitting semiconductor material, a lead frame where the die is actually placed, and the encapsulation epoxy which surrounds and protects the die (Figure 1). The first commercially usable LEDs were developed in the 1960s by combining three primary elements: gallium, arsenic and phosphorus (GaAsP) to obtain a 655nm red light source. Although the luminous intensity was very low with brightness levels of approximately 1-10mcd @ 20mA, they still found use in a variety of applications, primarily as indicators. Following GaAsP, GaP, or gallium phosphide, red LEDs were developed. These devices were found to exhibit very high quantum efficiencies, however, they played only a minor role in the growth of new applications for LEDs. This was due to two reasons: First, the 700nm wavelength emission is in a spectral region where the sensitivity level of the human eye is very low (Figure 2) and therefore, it does not appear to be very bright even though the efficiency is high (the human eye is most responsive to yellow-green light). Second, this high efficiency is only achieved at low currents. As the current increases, the efficiency decreases. This pr oves to be a disadvantage to users such as outdoor message sign manufacturers who typically multiplex their LEDs at high currents to achieve brightness levels similar to that of DC continuous operation. As a result, GaP red LEDs are currently used in only a limited number of applications. As LED technology progressed through the 1970s, additional colors and wavelengths became available. The most common materials were GaP green and red, GaAsP orange or high efficiency red and GaAsP yellow, all of which are still used today (Table3). The trend towards more practical applications was also beginning to develop. LEDs were found in such products as calculators, digital watches and test equipment. Although the reliability of LEDs has always been superior to that of incandescent, neon etc., the failure rate of early devices was much higher than current technology now achieves. This was due in part to the actual component assembly that was primarily manual in nature. Individual operators performed such tasks as dispensing epoxy, placing the die into position, and mixing epoxy all by hand. This resulted in defects such as epoxy slop which caused VF (forward voltage) and VR (reverse voltage) leakage or even shorting of the PN junction. In addition, the growth methods and materia ls used were not as refined as they are today. High numbers of defects in the crystal, substrate and epitaxial layers resulted in reduced efficiency and shorter device lifetimes. Gallium Aluminum Arsenide It wasnt until the 1980s when a new material, GaAlAs (gallium aluminum arsenide) was developed, that a rapid growth in the use ofLEDsbegan to occur. GaAlAs technology provided superior performance over previously availableLEDs. The brightness was over 10 times greater than standardLEDsdue to increased efficiency and multi-layer, heterojunction type structures. The voltage required for operation was lower resulting in a total power savings. TheLEDscould also be easily pulsed or multiplexed. This allowed their use in variable message and outdoor signs.LEDswere also designed into such applications as bar code scanners, fiber optic data transmission systems, and medical equipment. Although this was a major breakthrough inLEDtechnology, there were still significant drawbacks to GaAlAs material. First, it was only available in a red 660nm wavelength. Second, the light output degradation of GaAlAs is greater than that of standard technology. It has long been a misconception withLEDsthat lig ht output will decrease by 50% after 100,000 hours of operation. In fact, some GaAlAsLEDsmay decrease by 50% after only 50,000 -70,000 hours of operation. This is especially true in high temperature and/or high humidity environments. Also during this time, yellow, green and orange saw only a minor improvement in brightness and efficiency which was primarily due to improvements in crystal growth and optics design. The basic structure of the material remained relatively unchanged. To overcome these difficult issues new technology was needed.LEDdesigners turned to laser diode technology for solutions. In parallel with the rapid developments inLEDtechnology, laser diode technology had also been making progress. In the late 1980s laser diodes with output in the visible spectrum began to be commercially produced for applications such as bar code readers, measurement and alignment systems and next generation storage systems.LEDdesigners looked to using similar techniques to produce high brightness and high reliabilityLEDs. This led to the development of InGaAlP (Indium Gallium Aluminum Phosphide) visibleLEDs. The use of InGaAlP as the luminescent material allowed flexibility in the design ofLEDoutput color simply by adjusting the size of the energy band gap. Thus, green, yellow, orange and redLEDsall could be produced using the same basic technology. Additionally, light output degradation of InGaAlP material is significantly improved even at elevated temperature an d humidity. Current Developments of LED Technology InGaAlPLEDstook a further leap in brightness with a new development by Toshiba, a leading manufacturer ofLEDs. Toshiba, using the MOCVD (Metal Oxide Chemical Vapor Deposition) growth process, was able to produce a device structure that reflected 90% or more of the generated light traveling from the active layer to the substrate back as useful light output (Figure 4). This allowed for an almost two-fold increase in theLEDluminance over conventional devices.LEDperformance was further improved by introducing a current blocking layer into theLEDstructure (Figure 5). This blocking layer essentially channels the current through the device to achieve better device efficiency. As a result of these developments, much of the growth forLEDsin the 1990s will be concentrated in three main areas: The first is in traffic control devices such as stop lights, pedestrian signals, barricade lights and road hazard signs. The second is in variable message signs such as the one located in Times Square New York which displays commodities, news and other information. The third concentration would be in automotive applications. The visibleLEDhas come a long way since its introduction almost 30 years ago and has yet to show any signs of slowing down. A BlueLED, which has only recently become available in production quantities, will result in an entire generation of new applications. BlueLEDsbecause of their high photon energies (>2.5eV) and relatively low eye sensitivity have always been difficult to manufacture. In addition the technology necessary to fabricate theseLEDsis very different and far less advanced than standardLEDmaterials. The blueLEDsavailable today consist of GaN (gallium nitride) and SiC (silicon carbide) construction with brightness levels in excess of 1000mcd @ 20mA for GaN devices. Since blue is one of the primary colors, (the other two being red and green), full color solid stateLEDsigns, TVs etc. will soon become commercially available. Full colorLEDsigns have already been manufactured on a small prototype basis, however, due to the high price of blueLEDs, it is still not practical on a large scale. Other applications for blueLEDsinclude medical diagnostic equipment and photolithography. LED Colors It is also possible to produce other colors using the same basic GaN technology and growth processes. For example, a high brightness green (approximately 500nm)LEDhas been developed that is currently being evaluated for use as a replacement to the green bulb in traffic lights. Other colors including purple and white are also possible. With the recent introduction of blueLEDs, it is now possible to produce white by selectively combining the proper combination of red, green and blue light. This process however, requires sophisticated software and hardware design to implement. In addition, the brightness level is low and the overall light output of each RGB die being used degrades at a different rate resulting in an eventual color unbalance. Another approach being taken to achieve white light output, is to use a phosphor layer (Yttrium Aluminum Garnet) on the surface of a blueLED. In summary,LEDshave gone from infancy to adolescence and are experiencing some of the most rapid market growth of their lifetime. By using InGaAlP material with MOCVD as the growth process, combined with efficient delivery of generated light and efficient use of injected current, some of the brightest, most efficient and most reliableLEDsare now available. This technology together with other novelLEDstructures will ensure wide application ofLEDs. New developments in the blue spectrum and on white light output will also guarantee the continued increase in applications of these economical light sources. Practical use The first commercial LEDs were commonly used as replacements forincandescentandneonindicator lamps, and inseven-segment displays,first in expensive equipment such as laboratory and electronics test equipment, then later in such appliances as TVs, radios, telephones, calculators, and even watches (see list ofsignal uses). These red LEDs were bright enough only for use as indicators, as the light output was not enough to illuminate an area. Readouts in calculators were so small that plastic lenses were built over each digit to make them legible. Later, other colors grew widely available and also appeared in appliances and equipment. As LED materials technology grew more advanced, light output rose, while maintaining efficiency and reliability at acceptable levels. The invention and development of the high power white light LED led to use for illumination, which is fast replacing incandescent and fluorescent lighting. (see list ofillumination applications). Most LEDs were made in the ve ry common 5mm T1Â ¾ and 3mm T1 packages, but with rising power output, it has grown increasingly necessary to shed excess heat to maintain reliability,so more complex packages have been adapted for efficient heat dissipation. Packages for state-of-the-arthigh power LEDsbear little resemblance to early LEDs. Continuing development The first high-brightness blue LED was demonstrated byShuji NakamuraofNichia Corporationand was based onInGaNborrowing on critical developments inGaNnucleation on sapphire substrates and the demonstration of p-type doping of GaN which were developed byIsamu Akasakiand H. Amano inNagoya. In 1995,Alberto Barbieriat theCardiff UniversityLaboratory (GB) investigated the efficiency and reliability of high-brightness LEDs and demonstrated a very impressive result by using a transparent contact made ofindium tin oxide(ITO) on (AlGaInP/GaAs) LED. The existence of blue LEDs and high efficiency LEDs quickly led to the development of the firstwhite LED, which employed aY3Al5O12:Ce, or YAG, phosphor coating to mix yellow (down-converted) light with blue to produce light that appears white. Nakamura was awarded the 2006Millennium Technology Prizefor his invention. The development of LED technology has caused their efficiency and light output torise exponentially, with a doubling occurring about every 36 months since the 1960s, in a way similar toMoores law. The advances are generally attributed to the parallel development of other semiconductor technologies and advances in optics and material science. This trend is normally calledHaitzs Lawafter Dr. Roland Haitz. In February 2008, 300lumensof visible light per wattluminous efficacy(not per electrical watt) and warm-light emission was achieved by usingnanocrystals. In 2009, a process for growing gallium nitride (GaN) LEDs on silicon has been reported.Epitaxycosts could be reduced by up to 90% using six-inch silicon wafers instead of two-inch sapphire wafers. Illustration of Haitzs Law. Light output per LED as a function of production year, note the logarithmic scale on the vertical axis Technology Physics The LED consists of a chip of semiconducting materialdopedwith impurities to create ap-n junction. As in other diodes, current flows easily from the p-side, oranode, to the n-side, orcathode, but not in the reverse direction. Charge-carriers—electronsandholes—flow into the junction fromelectrodeswith different voltages. When an electron meets a hole, it falls into a lowerenergy level, and releasesenergyin the form of a photon. Thewavelengthof the light emitted, and thus its color depends on theband gapenergy of the materials forming thep-n junction. Insiliconor germaniumdiodes, the electrons and holes recombine by anon-radiative transitionwhich produces no optical emission, because these are indirect band gapmaterials. The materials used for the LED have adirect band gapwith energies corresponding to near-infrared, visible or near-ultraviolet light. LED development began with infrared and red devices made withgallium arsenide. Advances inmaterials sciencehave enabled making devices with ever-shorter wavelengths, emitting light in a variety of colors. LEDs are usually built on an n-type substrate, with an electrode attached to the p-type layer deposited on its surface. P-type substrates, while less common, occur as well. Many commercial LEDs, especially GaN/InGaN, also usesapphiresubstrate. Most materials used for LED production have very highrefractive indices. This means that much light will be reflected back into the material at the material/air surface interface. Thus,light extraction in LEDsis an important aspect of LED production, subject to much research and development. The inner workings of an LED I-V diagram for adiode. An LED will begin to emit light when the on-voltageis exceeded. Typical on voltages are 2-3volts. Refractive Index Idealized example of light emission cones in a semiconductor, for a single point-source emission zone. The left illustration is for a fully translucent wafer, while the right illustration shows the half-cones formed when the bottom layer is fully opaque. The light is actually emitted equally in all directions from the point-source, so the areas between the cones shows the large amount of trapped light energy that is wasted as heat. The light emission cones of a real LED wafer are far more complex than a single point-source light emission. Typically the light emission zone is a 2D plane between the wafers. Across this 2D plane, there is effectively a separate set of emission cones for every atom. Drawing the billions of overlapping cones is impossible, so this is a simplified diagram showing the extents of all the emission cones combined. The larger side cones are clipped to show the interior features and reduce image complexity; they would extend to the opposite edges of the 2D emission plane. Bare uncoated semiconductors such assiliconexhibit a very highrefractive indexrelative to open air, which prevents passage of photons at sharp angles relative to the air-contacting surface of the semiconductor. This property affects both the light-emission efficiency of LEDs as well as the light-absorption efficiency ofphotovoltaic cells. The refractive index of silicon is 4.24, while air is 1.00002926. Generally a flat-surfaced uncoated LED semiconductor chip will only emit light perpendicular to the semiconductors surface, and a few degrees to the side, in a cone shape referred to as thelight cone,cone of light,or theescape cone.The maximumangle of incidenceis referred to as thecritical angle. When this angle is exceeded photons no longer penetrate the semiconductor, but are instead reflected both internally inside the semiconductor crystal, and externally off the surface of the crystal as if it were amirror. Internal reflectionscan escape through other crystalline faces, if the incidence angle is low enough and the crystal is sufficiently transparent to not re-absorb the photon emission. But for a simple square LED with 90-degree angled surfaces on all sides, the faces all act as equal angle mirrors. In this case the light cannot escape and is lost as waste heat in the crystal. A convoluted chip surface with angledfacetssimilar to a jewel orfresnel lenscan increase light output by allowing light to be emitted perpendicular to the chip surface while far to the sides of the photon emission point. The ideal shape of a semiconductor with maximum light output would be amicrospherewith the photon emission occurring at the exact center, with electrodes penetrating to the center to contact at the emission point. All light rays emanating from the center would be perpendicular to the entire surface of the sphere, resulting in no internal reflections. A hemispherical semiconductor would also work, with the flat back-surface serving as a mirror to back-scattered photons. Transition coatings Many LED semiconductor chips arepottedin clear or colored molded plastic shells. The plastic shell has three purposes: 1. Mounting the semiconductor chip in devices is easier to accomplish. 2. The tiny fragile electrical wiring is physically supported and protected from damage 3. The plastic acts as a refractive intermediary between the relatively high-index semiconductor and low-index open air. The third feature helps to boost the light emission from the semiconductor by acting as a diffusing lens, allowing light to be emitted at a much higher angle of incidence from the light cone, than the bare chip is able to emit alone. Efficiency and operational parameters Typical indicator LEDs are designed to operate with no more than 30-60mWof electrical power. Around 1999,Philips Lumiledsintroduced power LEDs capable of continuous use at oneW. These LEDs used much larger semiconductor die sizes to handle the large power inputs. Also, the semiconductor dies were mounted onto metal slugs to allow for heat removal from the LED die. One of the key advantages of LED-based lighting is its high efficacy,[dubious-discuss]as measured by its light output per unit power input. White LEDs quickly matched and overtook the efficacy of standard incandescent lighting systems. In 2002, Lumileds made five-watt LEDs available with aluminous efficacyof 18-22 lumens per watt (lm/W). For comparison, a conventional 60-100 Wincandescent light bulbemits around 15 lm/W, and standardfluorescent lightsemit up to 100 lm/W. A recurring problem is that efficacy falls sharply with rising current. This effect is known asdroopand effectively limits the light output of a given LED, raising heating more than light output for higher current. In September 2003, a new type of blue LED was demonstrated by the companyCree Inc.to provide 24mW at 20milliamperes(mA). This produced a commercially packaged white light giving 65 lm/W at 20 mA, becoming the brightest white LED commercially available at the time, and more than four times as efficient as standard incandescents. In 2006, they demonstrated a prototype with a record white LED luminous efficacy of 131 lm/W at 20 mA. Also,Seoul Semiconductorplans for 135 lm/W by 2007 and 145 lm/W by 2008,which would be nearing an order of magnitude improvement over standard incandescents and better than even standard fluorescents.Nichia Corporationhas developed a white LED with luminous efficacy of 150 lm/W at a forward current of 20 mA. Practical general lighting needs high-power LEDs, of one watt or more. Typical operating currents for such devices begin at 350 mA. Note that these efficiencies are for the LED chip only, held at low temperature in a lab. Lighting works at higher temperature and with drive circuit losses, so efficiencies are much lower.United States Department of Energy(DOE) testing of commercial LED lamps designed to replace incandescent lamps orCFLsshowed that average efficacy was still about 46 lm/W in 2009 (tested performance ranged from 17lm/W to 79lm/W). Cree issued a press release on February 3, 2010 about a laboratory prototype LED achieving 208 lumens per watt at room temperature. The correlatedcolor temperaturewas reported to be 4579K. Lifetime and failure Main article:List of LED failure modes Solid state devices such as LEDs are subject to very limitedwear and tearif operated at low currents and at low temperatures. Many of the LEDs made in the 1970s and 1980s are still in service today. Typical lifetimes quoted are 25,000 to 100,000 hours but heat and current settings can extend or shorten this time significantly. The most common symptom of LED (anddiode laser) failure is the gradual lowering of light output and loss of efficiency. Sudden failures, although rare, can occur as well. Early red LEDs were notable for their short lifetime. With the development of high-power LEDs the devices are subjected to higherjunction temperaturesand higher current densities than traditional devices. This causes stress on the material and may cause early light-output degradation. To quantitatively classify lifetime in a standardized manner it has been suggested to use the terms L75 and L50 which is the time it will take a given LED to reach 75% and 50% light output respectively. Like other lighting devices, LED performance is temperature dependent. Most manufacturers published ratings of LEDs are for an operating temperature of 25Â °C. LEDs used outdoors, such as traffic signals or in-pavement signal lights, and that are utilized in climates where the temperature within the luminaire gets very hot, could result in low signal intensities or even failure. LED light output actually rises at colder temperatures (leveling off depending on type at around −30C). Consequently, LED technology may be a good replacement in uses such as supermarket freezer lightingand will last longer than other technologies. Because LEDs emit less heat than incandescent bulbs, they are an energy-efficient technology for uses such as freezers. However, because they emit little heat, ice and snow may build up on the LED luminaire in colder climates.This lack of waste heat generation has been observed to cause sometimes significant problems with street traffic signals and airport runway lighting in snow-prone areas, although some research has been done to try to develop heat sink technologies to transfer heat to other areas of the luminaire. Ultraviolet and blue LEDs BlueLEDs. Blue LEDs are based on the wideband gapsemiconductors GaN (gallium nitride) andInGaN(indium gallium nitride). They can be added to existing red and green LEDs to produce the impression of white light, though white LEDs today rarely use this principle. The first blue LEDs were made in 1971 by Jacques Pankove (inventor of the gallium nitride LED) atRCA Laboratories.These devices had too little light output to be of much practical use. In August of 1989, Cree Inc. introduced the first commercially available blue LED.In the late 1980s, key breakthroughs in GaNepitaxialgrowth andp-typedoping ushered in the modern era of GaN-based optoelectronic devices. Building upon this foundation, in 1993 high brightness blue LEDs were demonstrated. By the late 1990s, blue LEDs had become widely available. They have an active region consisting of one or more InGaNquantum wellssandwiched between thicker layers of GaN, called cladding layers. By varying the relative InN-GaN fraction in the InGaN quantum wells, the light emission can be varied from violet to amber. AlGaNaluminium gallium nitrideof varying AlN fraction can be used to manufacture the cladding and quantum well layers for ultraviolet LEDs, but these devices have not yet reached the level of efficiency and technological maturity of the InGaN-GaN blue/green devices. If the active quantum well layers are GaN, instead of alloyed InGaN or AlGaN, the device will emit near-ultraviolet light with wavelengths around 350-370nm. Green LEDs manufactured from the InGaN-GaN system are far more efficient and brighter than green LEDs produced with non-nitride material systems. With nitrides containing aluminium, most oftenAlGaNandAlGaInN, even shorter wavelengths are achievable. Ultraviolet LEDs in a range of wavelengths are becoming available on the market. Near-UV emitters at wavelengths around 375-395nm are already cheap and often encountered, for example, asblack lightlamp replacements for inspection of anti-counterfeitingUV watermarks in some documents and paper currencies. Shorter wavelength diodes, while substantially more expensive, are commercially available for wavelengths down to 247nm.As the photosensitivity of microorganisms approximately matches the absorption spectrum ofDNA, with a peak at about 260nm, UV LED emitting at 250-270nm are to be expected in prospective disinfection and sterilization devices. Recent research has shown that commercially available UVA LEDs (365nm) are already effective disinfection and sterilization devices. Deep-UV wavelengths were obtained in laboratories usingaluminium nitride(210nm),boron nitride(215nm)anddiamond(235nm). White light There are two primary ways of producing high intensity white-light using LEDs. One is to use individual LEDs that emit threeprimary colors—red, green, and blue—and then mix all the colors to form white light. The other is to use a phosphor material to convert monochromatic light from a blue or UV LED to broad-spectrum white light, much in the same way a fluorescent light bulb works. Due tometamerism, it is possible to have quite different spectra that appear white. RGB systems Combined spectral curves for blue, yellow-green, and high brightness red solid-state semiconductor LEDs.FWHMspectral bandwidth is approximately 24-27 nm for all three colors. White lightcan be formed by mixing differently colored lights, the most common method is to usered, green and blue(RGB). Hence the

Black Boy Isolation Essay

In Richard Wright’s book, â€Å"Black Boy,† the main character who also narrates the story is Richard himself since the book is written from his point of view; we find out a lot about how Richard feels and get detailed accounts of how he reacts to the things that happen to him. Even though Richard tries hard to relate to all groups of people around him, he cannot because he is so different, so much more independent and strong willed than the masses around him, these and other forms of isolation help shape Richard Wright’s character throughout the novel. In Richard’s neighborhood when he lives with his grandma, the thing that separates him most from everyone else is religion. Richard decided he is an atheist at a very young age, which also demonstrates his ability to think independently, even under pressure. He is persistent and stands by his view, because he cannot relate to the one imposed on him. He says, â€Å"Perhaps if I had †¦ remained basically unaffected. (pg 112) Richard believes that religion cannot give him anything more than he already has, so he rejects it as pointless even though everyone around him is trying to persuade him to accept God or else â€Å"lose his soul† and countless other threats. But, Richard is strong and doesn’t pay attention to any of these threats, which in a way separates him from his entire neighborhood. This and going to a religious school where all his peers have dry personalities, contributes to his isolation as a child. And, since he does not believe that God cares about him, this may increase his loneliness even more. So Richard starts to look to other things, such as writing, as a way to create a world for himself in which he does not feel isolated. Another group that he feels very far from is his immediate family. Ever since Richard was little, he has been beaten, threatened, scared and hungry and he mostly associates these feelings with members of his family. Because of the lack of love around him, Richard cannot believe in true love, which is a scar for life. For example when he meets Bess he says, â€Å"I stared at her†¦ then I was sorry that I had said it,† (pg 218. ) When Bess tries to be nice to Richard he is shocked and cannot understand how some people can love so purely and simply. He also comes to realize that he has a very different understanding of the word â€Å"love† than Bess because he has never been loved by anyone nor had any real family life. So, his isolation from his family early in life becomes a handicap later when he is unable to accept true love, which isolates him even more from people in his dult life. The last and most important group Richard cannot relate to at all is the white community. He is so different from the other blacks; willing to question racism, independent, not wanting to be treated like everyone else and with a deep, unique understanding that racism is wrong. He also voices his concerns more than the other blacks, so he has to bear a lot of violence and putdowns throughout his life. He has a conversation about this with Griggs, an old schoolmate: â€Å"Do you want to get killed? †¦ don’t anybody act a damn bit like it. (pg 183) and then contemplates this idea: â€Å"It was simply †¦ my way with everybody. † (pg 185) This is the most important isolation in the book because even though it applies to all blacks it applies to Richard even more because he is different from the whites as well as the blacks. This makes him not part of either community; he cannot understand the way black people act like whites are superior and he cannot understand the way white people act like blacks are inferior. Richard is again isolated from everyone around him. In conclusion, because of the ignorance and intolerance of all the people around him, black and white, Richard can never relate to anyone, which makes him lead a very lonely and detached life. This in turn motivates him to find a better life, whether it would be in the North or in novels/writing. Because of this isolation and narrow-mindedness of people around him, Richard aspires to be someone and to prove to the people who don’t believe in him and his values that he will continue to be an individual no matter what.

The Axial and Appedicular Skeleton

The Axial and Appendicular Skeleton Laszlo Vass, Ed. D. Version 42-0021-00-01 Lab RepoRt assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor. Purpose: ? What is the purpose of this exercise? ?Are there any safety concerns associated with this exercise?If so, list what they are and what precautions should be taken. Exercise 1: The Skull Questions A. Name the eight bones of the cranium. The eight bones of the cranium are the frontal, occipital, left parietal, right parietal, left temporal, right temporal, ethmoid, and sphenoid. B. What function do the cranial bones serve? The cranial bones serve to protect organs, such as the eyes, and the brain. C. List the bones that form the eye orbit. Zygomas, maxilla, lacrimal, frontal bone, sphenoid, ethmoid and palatine are all the bones that form the eye orbit.D. Examine the skull on the skeleton model and describe some ways in which the mandible is different from the other bones of the skull. The mandible is a joint that has no real attachment to any part of the body. It has a different range of motion than other joints in the body. E. Other than the skull, what are the other two components of the axial skeleton? xVertebral Column and Thoracic cage are two components of the axial skeleton. Exercise 2: Skull Markings Questions A. Which bone is palpated when touching the forehead?The temporal bone is palpated when the forehead is touched. B. What bone is palpated when touching the temple? The temporal bone is touched. Exercise 3: The Vertebral Column Questions A. What are the five categories of vertebrae in your vertebral column? Cervical, Thoracic, Lumbar, Sacral and Cocc yx are the five categories of the vertebrae. B. Why are lumbar vertebrae particularly prone to injury? A lot of individuals use their back instead of their legs to lift something heavy, which puts stress on the lower back. C. What is an intervertebral disc?What is its function? They are discs that are made of fibrocartilage and they are used to cushion the spine from shock. D. How are the sacrum and coccyx different from the other vertebrae? The vertebrae in these column sections are fused together as opposed to separately stacked. E. What is the overall function of vertebrae? It is one of the body’s major structure supports. It encloses the spinal cord and keeps the nerves from becoming damaged. Exercise 4: The Bony Thorax Questions A. What bones make up the bony thorax?The sternum, the ribs, and thoracic vertebrae make up the bony thorax. B. What is the function of the bony thorax? The function of the bony thorax is to protect the organs that are there. C. What category of bones are the sternum and ribs? The sternum and ribs are considered flat bones. D. Why are ribs 11 and 12 referred to as â€Å"floating† ribs? These two ribs are considered â€Å"floating† ribs because they aren’t attached directly to the sternum, but they are held on by cartilage. E. Propose a reason why the ribs are attached anteriorly by cartilage.A logical reason to why the ribs are attached anteriorly by cartilage is because of how the body flexes while still being able to protect some of the other vital organs in the thoracic cavity. Exercise 5: The Appendicular Skeleton Questions A. What is the pelvic girdle? What is its function? The pelvic girdle is where two coxal bones are placed. The take the weight of the body and is what the two lower extremities are attached to. B. What is the pectoral girdle? What is its function? This is where the scapula and the clavicle form the upper part of the body.This attaches the upper extremities to the core and is a ma in source of strength for the neck and upper body. C. Name the bones of the upper appendages (arm, forearm and hand). The upper appendage consist of the Humerus, Radius, Ulna, Olecranon Process, Carpals, Metacarpals and the Phalanges. D. Name the bones of the lower appendages (thigh, leg and foot). The lower appendage consists of the Femur, Patella, Tibia, Fibula, Tarsals, Talus, Calcaneus, Metatarsals and the Phalanges. E. Which of the four categories of bones do MOST of the bones of the appendicular skeleton fit into?Most of the bones in the human body are categorized as long bones. Conclusions Why is it important to relate the structures of the axial and appendicular skeleton to one another? It is important to relate the structure of the axial and appendicular skeleton because some of the bones function differently, yet look the same or they look the same and have different functions (i. e. legs are for walking while arms are for holding). A lot of the other bones form a structur e for weight bearing and others are more shock absorbers.

Its Not Suction essays

It's Not Suction essays The purpose of this experiment is to show the effects that air pressure has on a liquid and the necessity of oxygen for combustion. When a substance burns it is known as combustion. For combustion to occur oxygen must be present. Once a flame has used all of its oxygen supply it will die, this marks the end of combustion. Combustion stops occurring when the flame supplying the energy to a system goes out or the substance is completely used up. In a closed system in which combustion occurs, all of the oxygen within that system is used. When this occurs the air pressure outside of the glass is greater than the air pressure within the glass because the oxygen has been used up. Even though some new gases are produced, there is still less air pressure inside of the glass than there was originally. During combustion, some of the gases inside of the glass are used, which means that the pressure within the glass is now lower than the pressure outside of the glass. Since the air pressure outside of the glass is greater than that of the air pressure within the glass, the water level inside of the glass will rise. The water within the glass rises because the external pressure pushes down on the water with a greater force than the internal pressure does. Suction does not occur during this process because the force from the external pressure pushes the liquid into the glass. There is nothing inside of the glass pulling the liquid upward. - Melt a little wax and drip into the middle of the saucer. - Place the end of the candle into the wax and allow to harden. - Put 30 50 ml of water into the saucer. - Place the glass over the candle and onto the saucer. ...

Post Trauma Stress and self essays

Post Trauma Stress and self essays David G. Purves at London Guildhall University and Philip G. Erwin of the Psychology unit in Edge Hill College decide to do an experiment about Post Trauma Stress (PTS) and self-disclosure. The finding of this was posted in the Journal of the Psychology. The population they had chosen was a group of students from a local British University. There were a total of 200 students which contented 78 men, 116 women and 6 individuals who didnt indicate their gender. They started to look into both men and women dealt with stress after a traumatic event had happened to them. The hypothesized that men who engaged in less emotion disclosure had TSI ( Trauma Symptom Inventory) scores; these men were significantly less willing to disclose information or emotion about happiness. Also they looked at women who as their Trauma Symptom Inventory score increased so did their willingness to talk about their emotion about anxiety but when it came to talk about anything fear related whether it was emotion or information they were less willing to talk. Now when it came for David G. Purves and Philip G. Erwin to test out their theories they had decide on using a standard questionnaire, Trauma Symptom Inventory and Emotional Self-disclosure Scale. On this standard questionnaire is basic personal information (name, date of birth, gender) along with previous experience with a trauma. There was a number they could call if things they were bring up for the study was hard for them along with a statement saying anything brought up on the questionnaire or even in a conversation would be kept confidential and they would be not be identified. Next they used to the Trauma Symptom Inventory. Now this looks to see if a traumatic event has effect any of ten clinical subscales. It checks the traumatic impact in anxious arousal, depression, angerirritability, intrusive exp ...

Discuss the advantages and disadvantages of the Medicare Teen Dental Essay

Discuss the advantages and disadvantages of the Medicare Teen Dental Plan and if you consider this to be good public health policy - Essay Example This paper shall now discuss the different advantages and disadvantages of the Medical Dental Teen Plan. It shall also discuss whether or not the policy is a good public health program. This paper is being conducted in the hope of establishing a more analytical understanding of the Medical Dental Teen Plan of Australia. The Medical Dental Teen Plan of Australia is advantageous for the teenagers because their dental health services are now more affordable – no matter their station in life. Dental benefits for teenagers in Australia are supported by the government for up to $157 per calendar year for each teenager (Department of Health and Ageing, 2010). This includes a preventative dental assessment from a dentist who is accredited by Medicare Australia. Services from dental therapists and dental hygienists can also be availed by the teenagers with the supervision of the dentist (Department of Health and Ageing, 2010). Every year, there are about 1.3 million teenage Australians who are benefitted by the Medicare Teen Dental Plan. Moreover, even if the teenagers would opt for the services of their private dentist, they can still claim the benefit from the Medicare. In another option, the dentist can also claim the benefit directly from Medicare Australia for the services he would render to the teenager (Department of Health and Ageing, 2010). The Medicare Dental Teen Plan also gives an opportunity for those who are chronically ill to be managed by their general practitioner under the Enhanced Primary Care Plan (EPC) (Medicare Australia, 2010). This helps ensure that those who are chronically ill can still avail of medical and dental services despite the futility of the care which may be rendered to them. The Indigenous and Torres Strait Islander people can also benefit much from the Medical Dental Teen Plan. Many of those suffering from dental diseases belong to the aboriginal

Supply Chain Management exam Essay Example | Topics and Well Written Essays - 750 words

Supply Chain Management exam - Essay Example The risks associated related to each supplier is to be studied and evaluated. Also, a back up supplier should be selected who can supply in case the first supplier fails. The last step is to implement the strategy and employ regular evaluation of the supplier, its quality and performance. Methods should be used to increase the performance and reduce the extra costs of logistics through various service methods and technologies. Â   Question 2 In the existing scenario of volatile markets, organizations are searching for solutions to reduce costs along the entire enterprise chain. The key is to pursue both the strategic as well as tactical cost reduction and improvement measures which help the management to stay ahead in the com[petition. Further to balance out the long and short term margin pressures, cost reductions have become a necessity. Lean management has definitely been a stress reliever to companies in order to reduce waste and cut down costs. Lean management approach assist t he management to drive a continuous bottom up approach with regular small improvements down the line along all areas and departments in the chain. The fundamental approach of lean is to provide higher value to the end customer by increasing the product quality and reducing the waste. The five concepts of lean are – understanding the concept of the value addition stream and the waste being produced, staff training to help them reduce waste within their own working environment and nurturing the Lean culture among them so that they can become trainers for other teams. The main approach in the lean concept to reduce costs are as follows – 1. Identifying the value preference of the end user – since the end value of the product matters to the client, it is important that the management identifies those activities that add value to the product and those who do not. Activities who do not add value must b e eliminated and thus costs are automatically reduced. 2. Identify ing the true value stream or chain of activities – identifying the correct value stream which consist of those activities which when followed in the right sequence, provide the desired value for the customer. It is significant that the management identifies the correct sequence of activities that constitute the Value stream. This significantly reduces the waste that is generated in the value stream at some points where there is no order. 3. Enhanced Flow of the stream - Lean management lays stress upon steady and continuous flow of activities which support product value addition. Any kind of hindrances are identified by the lean approach and eliminated. 4. Pull approach rather than a push approach - In lean organizations, the production schedules are dictated by a pull approach and not by the arbitrary production plans of the shop floor personnel or Operations Managers. Most services would rather be pulled by the Customer Demand in the lean management. Production only in the case of demand leads to less inventories, less and optimal use of resources, and less cost. 5. Imporvement cycle – when the lean approach progresses within a system, it becomes easier to