CFC's and Ozone depletion Essay Example | Topics and Well Written Essays - 750 words

CFC's and Ozone depletion - Essay Example Therefore, appropriate action especially targeted against CFCs should be taken to reduce or stop the many negative effects of ozone depletion (Callan and Thomas  238; Miller 384). The ozone layer is basically ozone present in the stratosphere which protects the earth from ultraviolet radiation from the sun. In the early 1980s, scientists discovered that the ozone layer seemed to become thinner and thinner, till an â€Å"ozone hole† the size of North America was revealed over Antarctica. The theory largely accepted by scientists for this â€Å"ozone hole† is the presence of CFCs in the atmosphere. CFCs are a family of odorless chemical compounds which are normally used in air conditioning, refrigeration, insulation, packaging, and as aerosol propellants. Chemists found out that CFCs stay behind in the troposphere because they are chemically unreactive and thus not soluble in water. Although they are heavier than air itself, CFCs can levitate into the stratosphere mostl y through convection currents, random drifting, and the violent mixing of air in the troposphere. Once they enter the stratosphere, the CFC molecules separate under the impact of the high-energy ultraviolet radiation, releasing chlorine, fluorine, bromine, and iodine atoms. These atoms are highly reactive, and so hasten the breakdown of the ozone layer in a repeated chain of chemical reactions. ... The thinning of the ozone layer allows more harmful ultraviolet radiation to reach the earth’s surface. Research has proved that exposure of human skin to a certain type of ultraviolet radiation in sunlight is the main cause of basal cell and squamous cell skin cancers. Together, these two forms of cancers make up for ninety five percent of all skin cancers, and are responsible for about 2300 deaths in the United States each year. Moreover, these ultraviolet radiations increase the intensity of sunburns and cause immune system suppression. Besides this, ozone depletion reduces forest productivity for UV-sensitive tree species, decreases the population of certain aquatic species and surface phytoplankton (and as a result disrupts aquatic food webs), increases eye cataracts in particular species, and cuts down the yield of certain types of crops. What is more, the lessening of the ozone affects air pollution by increasing acid deposition and photochemical smog. CFCs, on the othe r hand, act as greenhouse gases and make the earth warmer, thus contributing to global warming (Miller 384, 385). As a result, it is extremely important to keep the level of ozone depletion and the amount of CFCs present in the atmosphere under control. One approach towards the emission of pollutants such as CFCs can be to replace them with other cleaner substances. For example, HFCs and HCFCs can be used in air conditioning equipment and refrigeration instead of CFCs because they have a lower potential of ozone depletion. The pathways by which these substances are emitted can also be altered to prevent them from entering the atmosphere. Old vehicles mostly use CFCs in air conditioning. Therefore, it is necessary to make sure that such vehicles are serviced by qualified technicians in

History Of Optic Fiber Usage Information Technology Essay

History Of Optic Fiber Usage Information Technology Essay The idea of fiber optics communication system is basically sending information through light. Optical fiber was first developed in 1970 as a basic communication purpose with a very low attenuation as transmitting light through fiber optics cable for long distance communication. In 1975, the first commercial fiber optics communication system was developed using semiconductor laser and operated at 0.8 Â µm wavelength and a bit-rate of 45 Mbps (Mega bits per second) up to 10 km (Elion Elion 1978) (Sullivan Curt 2003). In long beach California was the first live telephone traffic sent at about 6 Mbps and it was in 1977. After that, generations of fiber optics system technologies were developed, improved, and upgraded to achieve the first transatlantic operation in 1988. All fiber optics systems are limited by something called dispersion. The initial thought of fiber optics was an experiment involving a bucket of water and sunlight. It demonstrated the suns reflection within the bucket with a hole and water pouring out illuminating the water and the sunlight can be seen in the stream of water (Elion Elion 1978). Then it moved on to optical voice transmission known as photo phone. Further, it went to fiberscope that was used to inspect welds within reactor vessels, combustion chambers of the jet engines, and then to the medical field utilized in laparoscopic surgery. Researches and improvements continued through the fiber optics generations to overcome the dispersion phenomena by using dispersion-shifted fibers to minimize the dispersion at 1.55 Â µm or by limiting the laser spectrum to a single longitudinal mode (Alwayn 2004) (Sullivan Curt 2003). The idea of using fiber optical amplification came with the development of the fifth generation. The amplification development reduced the need of using repeaters and wavelength division multiplexing (WDM); which will be described in details later; and increases the data capacity. By these developments, a bit rate of 10 Tb/s was achieved in 2001. The developments of fiber optics generations are a continuous operation to especially for the huge market of the internet communications which requires an increase in communications bandwidth such as video on demand. These growing in using internet protocol data traffic are increasing side by side with faster rate integrated systems complexity. (Elion Elion 1978) Fiber optics manufacturers had reduced the cost by the huge request of communication companies such as ATT to take the advantage of delivering the technology of internet and telephone through higher data broadband services to customers homes (Sullivan Curt 2003) (Snell 1996). Fiber optics is already being used nowadays in military and commercial aircraft, and some of the areas it altogether replaced the Digital Flight Data Recorder with the newer Distributed Flight Data Acquisition Unit that performs the same thing but evaluates much more information. Indeed, future aircrafts will see fiber optics technology in the flight controls. Fiber optics has evolved practically from ideas to a thing of the future (Alwayn 2004) (Elion Elion 1978). Fiber optics Application The demand and usage of optical fiber has grown rapidly and optical fiber applications are numerous. Ranging from global networks to desktop workstation, telecommunication applications are widespread. These involve the transmission of data, voice, or video across distances of less than a meter to thousands of kilometers by utilizing one of a few standard fiber designs within one of several cable designs. Optical fibers are used by carriers to carry plain old telephone service (POTS) over their nationwide networks. Furthermore, local exchange carriers (LECs) employ fiber to carry the same service across central office switches at local levels and often as far as the individual home (fiber to the home, FTTH) or neighborhood (Alwayn 2004) (Elion Elion 1978). Moreover, optical fiber has a widespread use in transmission of data. Multinational firms require reliable and secure systems for transferring data and financial information among buildings to the computers of desktop terminals and around the world. Fiber is also used by cable televising companies in order to deliver digital video and data services. Due to the high bandwidth offered by fiber, it is the ideal choice for transmitting broadband signals like the high-definition television telecasts. Furthermore, intelligent transportations systems including smart highways equipped with intelligent traffic signals, changeable message signs, and automated tollbooths, also utilize telemetry systems based on fiber-optics (Alwayn 2004) (Fiber-Optics.Info 2010). Biomedical industry is another significant application of optical fiber. Fiber-optic systems are used in almost all modern telemedicine systems and devices for transmission of digital diagnostic images. Additionally, other applications for optical fiber also include military, space, industrial and the automotive sector (Elion Elion 1978) (Snell 1996). Fiber optics communication technology is used by todays telecommunications companies such as ATT in the United States and BT in the UK. Also it is used by internet providers and cable television signal providers such as Sky. For the huge expense of fiber optics system, the technology was first used for long-distance communication only. But, now days developments of the cities infrastructure had to take place to install the fiber optics communication system regardless of the cost and time consuming. The challenge of fiber optics technology companies was reflected positively on the market and the cost of fiber optics communications dropped considerably (Alwayn 2004) (Elion Elion 1978) (Fiber-Optics.Info 2010). By the developments of optical amplification system, an intercontinental network of 250,000 km of submarine-communication-cable was developed with a capacity of about 2.5 Tb/s was achieved. Also, the optical communication system was installed onboard aircrafts for data, video, and radio signals communication. It was first introduced to aviation industry by NASA researches on military aircrafts such as the first F/A-18 hornet through its RTDP; radar tracking and detecting system processor, missile video tracing system, and with the FLIR system; forward looking infra red sensor, and the integrated radar system with increased speed and memory capacity. Military aircrafts are always in-need to reduce weight when it is in slick phase to improve its capability of maneuvering and delivering various types of ordnance in a very precise targeting and accurate guidance. Lately, this technology was used on the F-22 airforce raptor on its high speed data bus and fiber optics transceiver (Alwayn 2004). This idea was reflected on the civil aircrafts later on as they always in-need to reduce weight to overcome the fuel usage and deliver larger number of passengers which means saving mo ney and increasing profits. Besides that, the new avionics systems technology and complexity required new communication system other than the copper wires such as the normal ARINCs (Fiber-Optics.Info 2010). Boeing and Airbus developed very complex integrated systems that control the aircraft performance at an altitude of 30,000 ft and above which required bigger and more complicated communication systems which means: More chance of shorting the wires. More EMI (electro-magnetic-interference) which can cause a distortion for the signals More weight More chance of shorting and cause sparks and fire on-board and aircraft The first official usage of fiber optics technology usage was on-board the Boeing 777 after the development of its AIMS (Aircraft Information Management System) which have more than 2 million of computer codes. Also Boeing 777 was the first aircraft to install an optical LAN (local area network) for on-board data communication and on its cabin systems communications (Sullivan Curt 2003) (Snell 1996). After that, fiber optics system was installed on the Boeing 757 flown by Air Mexico who did not experience a single failure. So here comes the safety, reliability, durability and stability of signals communications on-board an aircraft which can make the affordability part negligible. We have to mention that the cost of optical fiber systems are dropping for the establishments and marketing competition of huge number of manufacturers and suppliers (Alwayn 2004) (Fiber-Optics.Info 2010). Fiber Optics vs. Electrical Copper Wires: Fundamentally, there are three types of transmission media: copper wires, waveguides and free space. Copper wire, such as coaxial cable is broadly used. A signal is transmitted across the wire in either digital or analog form to a receiver placed at the end of the wire. Free-space transmission is also widely used through which radio, television and other across-the-air signals are carried. Waveguides describe the fiber-optic transmission. Significantly, a waveguide such as a optical fiber restrains the electromagnetic radiation, light (Bidgoli 2010). Fiber optic transmission provides the best elements of both free-space and coaxial transmission. It is capable of carrying a signal from point A to point B in the absence of any limited electromagnetic spectrum. Nonetheless, it does not suffer from limited data rate and bandwidth is the same way as the coaxial cables do. The advantages of fiber optics system over the copper wires are: No Electro-Magnetic-Interference (EMI). No radio-Frequency-interference (EMF). Immunity from electromagnetic noise High Signal quality Lighter weight cables Longer distance capability (Bidgoli 2010) Smaller diameter cables which mean saving more space. Greater bandwidth for data transfer Safety against shorting and sparking High bandwidth and greater information capacity Easy upgrade: Can be upgraded easier without ripping and replacing cable harnesses. Easier maintenance and handling, proved by Boeing and Lockheed martin engineers Lower cost (Bidgoli 2010) Lower signal loss for long distance communication Higher resistance against stress, temperature and vibration and higher lightning strikes incidence. Doesnt require repeaters for long distance communication Can operate for up to 100 km without passive or active processing But, we have to say that copper wires have some specifications that fiber optics doesnt: Can carry electrical power beside the signals Lower material costs Doesnt have minimum bending radius Can easily be installed between boxes and chips (Bidgoli 2010) Cable technology is used for connecting networks together; however, as optical fiber technology is moving forward, it is gradually replacing copper wires as an excellent medium of communication signal transmission. The main reason for this is that fiber optics offers much more benefits than conventional copper wires and cables, as stated above (Sullivan Curt 2003). Moreover, these benefits can be elaborated as follows: Resistance to Interference: Fiber optics do not conduct electricity as it is obtained from glass, which eliminates activities like grounding and makes it potentially immune to electromagnetic interruption. Working of Fiber optics, unlike copper cables, is based on light pulses that make it usable outdoors and in close proximity to electrical cables (Bidgoli 2010). Low Maintenance: This entails that optical fiber is not sensitive to elements like water and chemicals because it is produced from glass. Additionally, Fiber optics cannot be damaged by harsh elements. This makes the overall cost of maintenance and service lesser than its counterpart. Efficiency and Security: Information can be transmitted with greater fidelity with the help of fiber optics unlimited bandwidth. It can offer nearly 1,000 times as much bandwidth across distances approximately 100 times farther than copper cables. This provides a super-fast connection running in circles around the bandwidth assigned by cable connections. Moreover, since fiber optics is harder to tap than regular copper wires, it can offer additional data security (Bidgoli 2010). Picture Quality: In comparison to copper wires, the high quality technology embedded in fiber optics is much more powerful. One can obtain high-definition picture quality from fiber technology as there is no external interference. Safety: Fiber optics poses no threat of physical injuries during breakage of fiber optic cables. Instead of transmitting through electricity, it transmits data via light. Users face no risk of injury from dangers such as sparking, electrocution, fire, etc. (Bidgoli 2010). Interestingly, the benefits of converting into fiber technology such as Ethernet converters show proven advantages, considering that internet infrastructure is steadily making this transition rather than conventional copper cabling. Furthermore, applications of fiber optic include manufacturing and process control, supervisory control as well as data acquisition. Using transceiver modules provide a cutting edge and most importantly the highest quality data transmission for users television, home phone and internet (Sullivan Curt 2003). Basic components of fiber optics system: It is consisted of: Core: it is basically a cylinder of glass or plastic material. Cladding: a layer causing the light signal to be confined to the core by using the total internal reflection method. Buffer: a layer used to capsulate one or more core and cladding providing mechanical isolation and a protection from physical damage. Jacket: a further isolation and protection. Characteristics The major characteristics of optical fiber transmission lines are: Attenuation and its variation with transmission input wavelength, cable temperature and modal distribution. Radiation: and its variation with fiber temperature and bend radius Distortion and its variation with bandwidth, amplitudes, wavelength and modal distribution of the input light, length of the fiber, and lastly, environmental temperature (Snell 1996) Physical Parameters: This includes weight, size, ease of installation, total volume, coupling and splicing. Environmental parameters: This includes resistance to stress, water and chemical corrosion, temperatures and mechanical stresses (Alwayn 2004). Types: single mode and multi-mode fibers. A single-mode optical fiber Multi-mode optical fiber There are two categories of optical fibers, namely, single-mode fiber optical cable and multi-mode fiber optic cable. In essence, these types of fiber optic cables are comprised of numerous layers of glass, each having refractive index lower than the one next to moving from the center outwards. Since light is faster in lower glass refractive index, the wavelengths of light are broken outside the fiber, capable of traveling to the middle (Snell 1996). Multi-mode Fiber Optic Cable: Optical fiber with a base diameter greater than 10 microns can be analyzed through geometrical optics, and is called a multi-mode fiber. In this type of optic cable, the rays of light along the core of the fiber are led by total reflection. Moreover, rays meeting the core-mantle border at a high angle over the critical angle for this limit are fully considered. The critical angle is said to be the difference in refractive index between the mantle and core materials. Rays hitting the border at a shallow angle form the base breaks into the mantle and does not transmit the light and information along the fiber. Moreover, the acceptance of the fiber is determined by the critical angle, and is often referred to as a numerical aperture (Snell 1996). A greater numerical aperture allows light to spread into two distinct beams at different angles near the axis, for the effective coupling of light into the fiber. Single-mode Fiber Optic Fiber Fiber core diameter of nearly ten times the wavelength of light propagation is impossible to model with geometric optics. Rather, they can be studied as an electromagnetic structure by solving Maxwells equations that are reduced to the electromagnetic wave equation. It acts as an optical waveguide and supports one or more confined transverse modes which allows light to propagate through the fiber. Fiber that supports only one mode is known as mono-mode or single mode fiber. It is an extremely focused source of light which limits beams to a smaller range or angles closed to the horizontal. A fiber optic data cable has three primary functions. It converts an electrical input signal into an optical signal, transmit the optical signal across an optical fiber, and lastly, convert the optical signal back to an electrical signal (Green 2006). Transmitter: It is a semiconductor device and can be an LED (light emitting diode) or a laser diode. It converts the electrical input signal into an optical signal, and its drive circuit changes the current flow across the light source, which in turn changes the irradiance of the source. This process of changing the irradiance of the source as a function of time is known as modulation. Receiver: It is a photo-detector and the main component of the receiver which converts light signals into electrical using the photoelectric effects method. It is basically a semiconductor-based photodiode. Amplifier: it is used instead of the complex repeaters. It amplifies the light and optical signals without converting it to electrical. Fiber-optic telecommunication systems operate on pulse-code modulation in which information is sent across as a series of pulses. Moreover, the digital pulse-code modulation is coupled into a fiber and the fiber end set up by a connector in order to maximize the input power. In fiber-optic communication systems, semi-conductor lasers are best suited. Their shape and size enables efficient coupling of light within the small-diameter core of an optical fiber (Sullivan Curt 2003). The fiber then carries the light towards the receiver which detects the light and recovers the digital signal. As scattering, dispersion and absorption in the fiber degrade the signal, optical amplifiers must be used to regenerate the signal (Snell 1996). The U.S. military quickly turned towards fiber optics for enhanced and improved communications as well as tactical systems. During the early 1970s, a fiber optic telephone link was installed by the U.S. Navy aboard the U.S.S. Little Rock. Toward that end, The Air Force developed its Airborne Light Optical Fiber Technology (ALOFT) program in 1976. Greatly motivated by the success of these practical applications, military R D programs developed stronger fibers, ruggedized, high-performance components, tactical cables, and several demonstration systems that ranged from aircraft to undersea applications. Soon after, commercial application followed that included both ATT and GTE installing fiber optic telephone systems in 1997 in Chicago and Boston respectively (Green 2006) (Keller 2010). Therefore, these successful applications resulted in the increase of fiber optic telephone networks. In the early 1980s, single-mode fiber running in the 1310 nm and then in 1550 nm wavelength ranges we re installed for these networks. Earlier, information networks, computers and data communications were far slower to employ fiber; however, today they are embracing the transmission system that has lighter weight cable, carries more data faster and across long distances, and resists lightning strikes (Elion Elion 1978) (Snell 1996). An average aircraft consists of over hundred miles of electrical wires and controls almost everything from landing gear to calls from flight-attendants. These insulated copper wires have proven to be a big bottleneck: it is heavy in weight, vulnerable to electromagnetic interference and if not accurately maintained, can cause system failures or fires. Some of these wires can be replaced with fiber-optic technology that is lighter than copper wire, immune to electrical shocks, and less sensitive to electromagnetic interference (Green 2006). Researchers have developed a new optical switch to be incorporated into the cockpit controls in order to manage operations that involve turning on and off, for instance, displays, landing gear, manual switching between fuel tanks, etc. Presently, on-off switches in a cockpit are connected to separate wires spread throughout a plane, controlling several functions. In case a switch fails to work due to wiring problems at the inside of the plane, dete cting the offending line can consume a lot of time and effort, since the wires are usually bundled together. Therefore, this switch is capable of sensing whether a button has been pressed fro off to on (Keller 2010). Then, the information from the fiber-based device can be directed toward a main fiber artery that carries hundreds of signals simultaneously. Through this, the bulk of wires, and cost is eliminated, and maintenance is simplified. Although engineers have been working to replace aircraft wiring with fiber for several years, unfortunately, they have had only moderate success. Built in mid-1990s, Boeings 777 uses a fiber-optic communication network, but the design and implementation being a part of an experiment. Moreover, the network was not a critical system and it was over-designed with more possibility of error than greater cost-effectiveness if in case it was broadly implemented in the industry. Nevertheless, Boeings 787 aircrafts, is equipped with a more cost-effectiv e optical fiber communication network (Green 2006) (Keller 2010) (Sullivan Curt 2003). ARINC 429 The first major variation in avionics databusing on military as well as commercial aircraft came during 1970s and 1980s. It was deployed as a 100 kilobit-per-second ARINC 429 databus which is a multiplex databus standard of ARNIC Inc. The databus is omnipresent on commercial airliners and is one of the most common avionics equipment used in flying today. The ARNIC 429 is equipped by all commercial aircrafts for legacy connections and for securing backup for flight critical controls. The ARNIC 429, apart from being the de-facto standard, is used on aircrafts for digital electronics, navigation and air data computers, engine control systems, and radios which are fully computerized and need to interact with each other. Furthermore, ARINC 429 is greatly responsible for setting up the digital era in commercial and military avionics. However, it is a comparatively slow twisted-pair databus and unidirectional like 1553. Only one terminal on the bus can broadcast and as much as 20 terminals can listen (Keller 2010). The ARINC 429 represents a tightly legalized architecture equipped with standard ARINC connectors. Before the introduction of ARINC 429, avionics designers utilized hard-wired point-to-point connectors with analog signals suitable for every sensor type, like the navigation gyros. Many sensors had multiple wires and multiple signals. In typical applications deployed on todays jetliners, systems designers extensively utilize ARINC 429 in order to connect avionic subsystem boxes and components digitally. One master subsystem on the bus sends information to at least 20 slave subsystems, but the slaves are unable to send information back to the master. Therefore, to enable a slave subsystem to transmit data back to the master, another ARINC 429 bus is used with its direction reversed, thereby enabling the original slave to send and the original master to listen. More frequently, designers make use of two ARINC 429 buses, amounting to point-to-point bi-directiona l interconnections between avionics subsystems: one bus transmitting in one direction, and another bus transmitting in the reverse direction (Green 2006) (Keller 2010). One such example includes jetliners flight-management computer that accepts and processes inbound signals from several different sensors and other subsystems, and estimates the paths taken by flights, their time of arrival, fuel burn, etc. In this approach, ARINC 429 busses send information from the sensors and allow the flight-management computer to listen to that data. Whenever the flight-management computer needs to transmit information tack to a particular sensor, designers employ another 429 bus that runs in the opposite direction. Regardless of its low speed, the digital ARINC 429 databus aids in increasing the efficiency, speed, and facilitates maintenance since it can move several digital data packages across the same twisted pair, where analog approaches required a different wire for each signal (Keller 2010). The digital ARINC 429 bus allows for multiplexing of the information on two wires. Since it is capable of sending data across only in one direction, it is greatly reli able due to its lower possibility of data corruption or data conflicts. Furthermore, this reliability of the databus makes it usable and well-known for flight-critical data involving avionics activities such as flight navigation and engine control (Keller 2010). The sheer size of ARINC 429 installed base drives its popularity; it is included in almost every commercial jetliner recently manufactured. ARINC 429 has limited addressing capacity and limited bandwidth; still it is proved as a highly robust physical bus and has served the industry well enough for several years. Moreover, it is a viable bus and protocol where installations require limited bandwidth and limited address space on the bus. However, modern avionics architecture demands more bandwidth, more address space, and greater flexibility than what the ARINC 429 can deliver (Keller 2010). ARINC 629 ARINC 629 is a 2-megabit-per-second databus that is borne from the MIL-STD-1553 technology. The conversion into an ARINC 629-type of bus topology strongly supported the move in the aviation industry to greater degrees of integration within the full systems throughout the avionics and the aircraft systems. The launch of ARINC 629 was set up on the highly-advanced architecture of the Boeing 777 double-engine jumbo jetliner. After its launch, the databus started as a Boeing invention known as Digital Autonomous Terminal Access Communications (DATAC). In comparison to ARINC 429, 629 is a completely different model altogether. It is bi-directional and does not need the master, which has been a potential single point of failure in 429. Although it is a sporty technology, it is still expensive. Additionally, ARINC 629 is far more cognate to 1553 than the ARINC 429, which has bi-directional flow of data (Keller 2010). One of the most attractive aspects of ARINC 629 was the bus efficiency, or rather the ratio of actual data transmitted by the bus to the routing overhead code. ARINC 429 has an efficiency of nearly 45 percent; however, with ARINC 629 efficiency can reach up to 85 percent if the bus is architected right. Furthermore, as compared to 429, ARINC 629 is a bus without connectors. In the ARINC 629 a twisted pair of wires is fed across the bus coupler that behaves like a transformer. Nonetheless, it was the price of the bus that got designers in a dilemma about the usage of ARINC 629. Although, ARINC 629 was more reliable, but it was much costlier than what the designers had actually thought (Keller 2010). Cost concerns, a lack of large new commercial aircraft projects when Boeing developed the 777, and the increasing popularity of Ethernet networking technology blended together to halt implementation of the ARINC 629 after the 777. ARINC 629 is heavy and expensive to implement. Future Fiber optics is anticipated to have a better future in military aviation industry. It exclusively provides high bandwidth, immunity against electromagnetic interference, and is light weight. Optical fiber was deployed on the AV-8B several years ago; it is used across the F/A-18E/F including several other aircrafts, and is likely to be fielded at a higher degree in coming years. However, before fiber-based applications in intense aviation environment can proliferate, a couple of standards are required in component, training, testing and other areas. Techniques such as WDM, short for wavelength division multiplexing, might dramatically increase the throughput and lower the footprint needed today for analog and digital data communications, beyond the immediate horizon (Keller 2010) (Sullivan Curt 2003). Fiber optic standardization within the aerospace sector leaves out something to be desired. Unfortunately, there are no standards for: The method for computing link loss power budgets The geometrics of critical parts like the end faces of optical fiber cable terminations, and Training military aviation personnel and technicians in the handling of optical fiber There has been a consensus for standardization. Operating with the Society of Automotive Engineers (SAE), NAVAIR, short for Naval Air Systems Command, avionic companies, airframers and components suppliers have put extreme efforts in developing training standards and components to enhance the supportability of current systems, and to cover various emerging technologies. In essence, fiber optics has been a corporate initiative within NAVAIR, holding its base in the commands Avionics Division instead of a particular program office (Adams 2005). Fiber optic technology has evolved at the major contractor or airframer level, in military aviation, as stated by researchers, engineers, personnel, and F/A-18 fiber optic experts with PMA 265 at NAVAIR. Fiber optics avionics components standardization will greatly assist in eliminating ambiguities and allowing test and inspection of equipments in order to sufficiently cover the technology fielded today (Adams 2005) (Sullivan Curt 2003). JELLI JELLI is an SAE group that is developing performance standards for the initial test and inspection processes of avionics fiber optic assemblies. JELLI is short for jumpers, endfaces, link loss and inspection; i.e. the processes and components used in optical networks. They are supported by the following definitions: Jumpers: The cables that are utilized in testing the overall optical performance of the fiber optic cables after installation. Endface: This is the polished end of the high-precision ceramic cap of the fiber optic termination that enables optical coupling. Link Loss: It is the attenuation of the signal, primarily from connector loss, and Inspection: It involves the examination of a cable installation in order to verify its performance. Different polish standards are required to apply to the physical vs. non-contact connections. However, within those areas, everyone should satisfy a termination endface range for that kind of polish. The cleanness of the endface is another important parameter. Test jumpers have endfaces and their polish requirements must match the component being installed within the aircraft. The test jumpers fail work on the airplane without such as standard (Adams 2005). Furthermore, standards for components like endfaces are essential to eliminate subjectivity on the engineering side. Additionally, it is mainly important since aircrafts with fiber optic systems have been launched in order to set up a baseline for the avionics technicians, and to instruct them on what exactly a good connector endface. In essence, work on inspection involves the magnification and several other criteria required of the equipment that is used for examining the termination endfaces and detect damages. For instance, tiny char

Philosophy of Education as a Means to Educate Humanity in a Diverse Sou

Philosophy of Education as a Means to Educate Humanity in a Diverse South Africa ABSTRACT: In pre-democratic South Africa, people never learned to listen to the stories of their fellow human beings because that was seen as a threat rather than a challenge. With the long-awaited political and constitutional changes taking place, a different societal structure is being established and a new democratic value system formally and officially being embraced. It would, however, be naive to imagine that policy changes would transform deeply-rooted attitudes, practices and existing structures overnight. The change into a democratic society does not mean, unfortunately, that a political, social and educational utopia is being created instantly. All learners will have to develop the skills, knowledge competence and attitudes to function effectively in a culturally diverse society. It will require a major paradigm shift from most educators, philosophers of education, and teacher trainers, as well as parents. I will argue for a pluralistic, problem-centered approach to teacher education and training that would be helpful in educating students to respect others and diversity. 1 INTRODUCTION In 1948 the National Party won the election in South Africa and introduced its policy of apartheid. Education became a political battle field, without considering educating human beings for a human society. A narrative of power was followed. The school was used as an instrument to support and legitimise the position of the dominant group and its political interests. The culturally divided population was kept divided to ensure the dominant group's position in all spheres of society. Conformity to and continuity of the ideologies and culture of ... ...nnecticut: Bergin and Garvey. SQUELCH, J. (1993) Towards a Multicultural Approach to Education in South Africa. In: The Black Child in Crisis - a Socio-educational Perspective edited by J. le Roux. Pretoria: JL van Schaik. TAYLOR, C. (1985) Philosophy and the Human Sciences. Cambridge: Cambridge University Press. VAN DER VYVER, J. (1998) The Democratisation of Assessment in a Pluralistic, Problem-centred Module in Philosophy of Education at Post-graduate Level. South African Journal for Higher Education, 12(2):183-197. VENTER,E. FRANZSEN, K. AND VAN HEERDEN, E. (in press) An Analysis of the Effect of Recent National Policy Changes on Values and Education in South Africa. In: Education, Culture and Values - Volume 1. Systems of Education, Theories, Policies and Implicit Values edited by Mal Leicester, Celia Modgil and Sohan Modgil. London: Falmer Press.

Most Effective Hand Cleaner

Most Effective Hand Cleaner Introduction: The purpose of this experiment is to: (a) determine if hand soap or alcohol gel is the most effective in killing Staphylococcus aureus (b) obtain the statistical difference of effectiveness in killing S. aureus between hand soap and alcohol gel. The null hypothesis is that neither hand soap nor alcohol gel is effective in killing S. aureus more than the control group which is nothing at all. The alternate hypothesis is that hand soap versus the control group will be more effective in killing S. ureus and/or alcohol gel versus the control group will be more effective in killing S. aureus. Another alternate hypothesis is that alcohol gel is more effective in killing S. aureus than the hand soap. Materials and Methods: The bottom of a Trypticase Soy Agar (TSA) plate is divided into three (3) pie sections along with the experimentalist initials, class day and class time. A sample of S. aureus is obtained in a closed lid sample tube. The sample tu be is rolled back and forth to suspend the organism evenly while wearing gloves. The sterile swab is dipped into the test tube to obtain S. aureus, and then closed. The petri dish lid is opened just long enough to gently apply the swab in a streak pattern rotating the plate at different angles. The lid is placed on the petri dish and the contaminated swab is disposed in the biohazard bag. A blank disk is placed in the center of section one (1) with sterile tweezers. A second disk is dipped into hand soap and placed in the center of section two (2). A third disk is dipped into alcohol gel and placed in the center of section three (3). Each disk is softly tapped into media to secure. The petri dish is placed bottom side up in an incubator set at 37 degrees Celsius for three (3) days and then placed into refrigerator. Two (2) weeks later the diameter of the zone of clearing around the disk from each section is measured in millimeters. The data is collected from each class and is compiled to calculate the mean, standard deviation, and SEM. The compiled data is analyzed by creating a bar graph to compare the zone of clearing for each group. Results: DATA| CLASS STASTICS| Treatment Groups| Clear Zone (mm)| Mean (mm)| Standard Deviation| SEM| Error Bars| | | | | | Mean + (1. 96) SEM| Mean – (1. 96) SEM| 1. Blank Disk| 0| 0| 0| 0| 0| 0| 2. Hand Soap| 15| 11. 21| 3. 65| 0. 74| 1. 46| 1. 46| 3. Alcohol Gel| 15| 13. 21| 3. 93| 0. 80| 1. 57| 1. 57| Discussion and Conclusion: There was a significant difference between the control group and the treatment groups. The control group had no effect on killing S. aureus, but the treatment groups did have an effect on killing S. aureus. The hand soap mean zone of clearing was 11. 21mm and the alcohol mean zone of clearing was 13. 21mm. The null hypothesis that neither hand soap nor alcohol gel is effective in killing S. aureus more than the control group is rejected. The alternate hypothesis that hand soap versus the control group is more effective killing S. aureus is accepted. The alternate hypothesis that alcohol gel versus the control group is more effective in killing S. aureus is accepted. The alternate hypothesis that alcohol gel is more effective than the hand soap in killing S. aureus is rejected. The data suggests hand soap is not as effective as alcohol gel; however, statistically, the data does not support that alcohol gel is a more effective treatment because the error bars overlap. In conclusion, cleaning hands with either hand soap or alcohol gel is better at killing S. aureus than using nothing at all.

Sarbanes-Oxley

Securities Exchange Commission is the highest authority which administers and monitors the audit of U. S Listed Companies at NYSE, NASDAQ and Dow Zones. All U. S. Listed Companies which get traded at U. S. bourses, have to comply with the FASB rules and practice GAAP standards of accounting. Non-compliance to any of the auditing rules prescribed by GAAP would be seriously viewed. U. S. Federal Government works in the interest of public investors and it expects all public companies to work in a transparent method by disclosing fair transactions in annual financial statements of all public companies. Particularly, with the collapse of Enron, which is the world’s largest corporation, which shocked the entire corporate world, with the clean opinion of company’s auditor. , Arthur Anderson. The emphasis here is more on auditing committees and board of directors of the company who must participate and work without any prejudicial interest, with the fact that Board of Directors are the fiduciary officers of a company who work and intermediate between shareholders and management of the company whereas Auditors are the representatives of public investors who must in all respects protect and safeguard the investments of public. In spite of highly qualified CFOs, COOs and CEOs, who are penalized for falling part of the non-compliance, officers also invite criminal charges. In order to prevent future scandals in corporate America and also to protect all the investments of investors, President Bush signed the law of SOX on 30th July, 2002 and it was passed through Congress for unanimous support. For the common investor, SOX is a great saver and also enables complete transparency about a public listed company. Further this is also in the interest of Federal Government whose responsibility to safeguard the international businesses and nation’s economy. Discrepancies found in Enron that laid foundation to SOX Enron filed bankruptcy in the year 2001 and the company’s share dropped down from $ 90 per share to $ 0. 30 cents per share. Fortune magazine named Enron as â€Å"America’s most innovative Company†. Enron had nearly $ 101 billion revenues prior to the filing of bankruptcy and it was the most successful company in United States in supplying electricity and natural gas. Surprisingly, all the credit rating agencies viz. , S&P, Moody’s Investors Service, Fitch Rating have given all good credit ratings until Enrol filed Chapter 11. According to SOX reporting standards , some of the discrepancies found in Enron are viz. , successive resignations of management, inaccurate and unreliable financial statements, CEO stock sales during blackout period, nondisclosure of earlier CEO stock sales, off-balance sheet transactions to hide losses, destruction of documentation and rigging of ratings. After three months of collapse of Enron, another giant Internet company Global Crossing Ltd. , filed its bankruptcy indicating its financial condition. WorldCom followed by Tyco went completely bankrupt indicating disability to run the companies any longer. One common factor in all of the above companies, is either mismanagement or non-practice of professional accounting procedures which yielded the companies to its last stage of fate and certainly, this could have been prevented by methodical and professional accounting procedures particularly with the authentication and certification of Auditors who in all probability are relied upon by the SEC and Federal Government. Therefore, the emphasis here is that auditors have to be free and fair in certifying the financial statements and in order to thoroughly screen the public companies, without leaving any scope for fraudulent account procedures, U. S. Government has initiated SOX law in the year 2002. (Jill Gilbert Welytok Sarbanes-Oxley for Dummies) Literature Review What is SOX law? Sarbanes-Oxley Act of 2002 also called as SOX is mandatory for all organisations including large and small. This legislation is aimed at enforcement of financial practices, regulations and to ensure corporate governance. Sarbanes-Oxley is named after Senator Paul Sarbanes and Representative Michael Oxley, who were main designers in setting number of deadlines for the compliance of legislation. SOX is arrnaged in eleven titles. Some of the most importance sections with regard to the compliance are sec. 302, 401, 404, 409, 802 and 906. Compliance through SOX has to be performed methodically, through proper analysis and study. After a thorough work, SOX leaves no scope for any fraud or misrepresentation of facts and figures and by far, it recommends all the organisations to act in a credible manner stating that â€Å"don’t put off until tomorrow what can be done today! † in order to save companies and also refraining from adverse consequences caused by lenient views either by audit committees or by the management of the companies. SOX has helped many companies to draw benefit from the compliance of regulations as it provides a clear picture of financial status of the company and to those who would like to have to access to the information about a particular company. Further, this also helps the U. S Government to keep a watchful eye on the financial status of companies and keeps a vigilance on the financial system of companies. (A guide to the Sarbanes-Oxley Act 2002) Methods Section 302 of SOX This section is listed under Title III of the Act and details about â€Å"Corporate Responsibility for Financial Reports†. Section 302 states that periodic filing of statutory financial reports should be certified by the signing officers who must review the report. The report must not contain any untrue or false statements or omissions or misleading statements. The financial statements must state only related information which is fairly presented and must also reflect on the financial condition of the company and must also details the results of all material facts and aspects. The signing officers are responsible for all internal controls and must evaluate these internal controls within previous 3 months and must have reported on the findings. A list of all deficiencies if any found, in the internal controls or any fraud information that involves the employees of the company who are involved in internal activities must be stated. Any significant change or observation made by the signing officers, within internal controls which can negatively impact must be reported by the officers. All the provisions of this Section cannot be avoided by transferring or reincorporating the activities of a company outside United States. Whether company is operating within United States or outside United States, must comply with this Section as a registered company under Securities Exchange Commission. (A guide to Sarbanes-Oxley Act 2002, summary of section 302) Section 401 of SOX This section is listed under Title IV of the Act and discusses about â€Å"Disclosure in Periodic Reports†. Financial statements published must be accurate and must not contain any incorrect statements or admit the fact that material information is stated. Financial statements apart from regular Profit & Loss Account and Balance Sheet, also include off-Balance Sheet liabilities, obligations or any transactions. To this effect, the Commission would study and report with a complete analysis of off-Balance Sheet transactions and to what extent these are transparent. The Commission has also to decide whether GAAP principles or any other regulations are resulting in its reporting. Section 404 of SOX This section is listed under Title IV of the Act and discusses about â€Å"Management Assessment of Internal Controls†. All Annual Reports of companies have to publish information about the scope and adequacy of the internal control structure and other procedures with regard to financial reporting. This statement must also confirm the effectiveness about internal controls and procedures. A registered accounting firm can also attest and report on the assessment and about effectiveness of the internal control procedures for financial reporting. Section 409 of SOX This section is listed under the Title IV of the Act and details about â€Å"Real Time Issuer Disclosures†. Issuers are required to provide information on material changes pertaining to financial conditions or changes. Public must have access to information on urgent basis and no delay can be made. These disclosures have to be presented in an easy and understanding manner and the information should be qualitative with graphic presentations as required. Section 802 of SOX This section is listed in Title VIII of the Act and pertains to the â€Å"Criminal Penalties for Altering Documents†. This section states that penalties and fines or imprisonment up to 20 years is levied on the persons who are responsible for altering, destroying, concealing, falsifying records or documents or tangible objects. This act done either with an intention to obstruct, impede or to influence a legal investigation is seriously viewed by the SOX officers. Further this section also imposes penalty or fine or imprisonment up to 10 years on any accountant who knowingly or willfully violates the provisions of this section or violates the maintenance of audit or review of papers for a period of 5 years. Discussion SOX is divided into many parts and each part carries certain specific rules and regulations which are prescribed for easy understanding of corporates. SEC-Rules states about SOX SEC Rules and Regulations, which states that officers have to certify about the maintenance, regularity and establishment of effectiveness of the issuer’s internal controls. IC-Primer states about internal control framework, risk control, assessments, audit programs relating to Sections 302 and 404 regarding Certification of Disclosure and Managements’ Internal Controls and Procedures. This framework established by COSO/SAS-78. SOX Act 2002 is aimed at to improve the quality and transparency in financial reporting, independent audit and accounting services for public companies and also to create a Public Company Accounting Oversight Board, to work towards setting up of standards for best accounting practices and also to strengthen the independence of audit firms who audit public companies. Further SOX is aimed at to increase the corporate responsibility and the useful advantages of financial disclosure, to protect the independence of securities analyst and also to improve the Securities and Exchange Commission resources for all purposes. SOA-Manual lists all the key dates and timetable, self-assessment questionnaires, definitions relating to Titles II and III regarding Auditor Independence and Corporate Responsibility. Forms have to be prepared independently or by the assistantship of a practitioner who is engaged to perform accounting compliance services. (Sarbanes-Oxley Act 2002, Financial and Accounting Disclosure Information) According to Pricewaterhouse Coopers Report 2006, â€Å"Audit Committees Effectiveness, what works best† focus and emphasis is more on financial statements, compliance and ethics, relationship with external auditors, risk management and internal control which discuss as to how effective practice of auditing can be conducted in organizations. There is also an emphasis about external auditing and internal auditing which is conducted periodically within the internal environment by internal audit committees and whose report can reveal much accounting information about the recording of business transactions of organizations. After the year 2002, which witnessed the unfortunate events in U. S. corporate sector, the entire corporate world, stood up for more accuracy and correct presentation in financial statements. A quote which states â€Å"prevention is better than cure† which is applicable in health, is also now applicable to corporate sector with the fact that, companies would never reach to the last stage of liquidation or bankruptcy, if the companies had been properly conducting internal audits and external audit, and thoroughly complying with the auditing procedures and has been GAAP accounting practices, worst state-of-affairs could have been prevented and many companies could be saved. Another development in the corporate sector that is to be noted is, loss making companies or companies that are performing low in business, are finding many potential ways to save the companies by mergers or acquisitions. In the recent years, throughout the world there have many mergers and acquisitions (M&A). For example Daimler-Benz is now called as DaimlerChrysler, JP Morgan & Chase Co. , purchased Bank One Corp, CitiCorp purchased Travelers Group, AT&T Inc purchased Bell South Corporation. It can be stated here that, M&A activity saved many companies in the past decade and even saved jobs of many people. Apart from M&A activity, SOX Act is equally protecting companies and public investments and there can be absolute assurance about the compliance of SOX regulations. This is due to the fact SOX aims at checking the fraudulent working of organizations. From another angle, SOX Act credibility is also being questioned by the legislative authorities and another alternative is also being looked for future business regulations. According to the authorities, who believe that the advantages of SOX would never last long which is why another source of compliance is being searched. (How Does The Sarbanes-Oxley Act Impact American Business? ) However, the Federal Government continues to update SOX mandates and in the year 2007, U. S. Securities and Exchange Commission (SEC) approved new auditing standard for internal controls. In order to bring more awareness about auditing, SEC and PCAOB are encouraging auditors to undertake risk-based approach in the evaluation of internal controls on financial reporting of public companies. There are many benefits from SOX compliance such as findings can be used in evaluations, it would reduce the costs associated with risk assessment, it would also reveal the risks that an organization is confronted with and the remedial measures available to manage risk, help companies to begin groundwork for risk assessment and to introduce more regulations and specifications and further a risk management program can be developed through SOX compliance. As stated above the success of SOX is quite benefiting to both American companies as well U. S. Federal Government with the fact that SOX identifies assets and activities, monitors the activities and ensures accuracy in financial statements which is the most important activity in checking the health of a listed company. Access to data wherever required demonstrates and indicates the practice of Accounting Standards according to FASB Rules and it reveals complete business transactions of a company. SOX can also retrieve entire events, records, commands given to data server and find out whether there is any mismanagement, forgery or fraudulent activity in the accounting procedures. SOX also generates audit reports which gives a full length of information about each and every company. The information that is provided by SOX enables Government to take necessary steps to issues notices or memos to U. S companies to make necessary corrections wherever required and can also provide plans for remedial measures to save the companies from liquidation. SOX is a wake up call for many American businesses and also to all those foreign companies which are venturing into business with American companies. Conclusion SOX continues to keep the companies under check and investigation about the compliance of accounting procedures as laid in FASB Rules and also about the compliance of auditing procedures in internal controls. It is very difficult for American companies to evade any procedures which come under the purview of SOX and therefore, there is expected to be a neat and clean organizations with excellent auditing committees.