Per Clausewitz’s On War Essay Example for Free

Per Clausewitz’s On War Essay Per Clausewitz’s On War focal points on how victory can be achieved, reader see a keen interest in how to disarm the enemy using reciprocal and proportionate â€Å"efforts to his powers or resistance. † This implies that to win a war you might use all means, strength, and resources within your power to deliver the best strategy possible. Using â€Å"calculation of probabilities† victory can achieved by fully knowing what is at stake and how to attack at the right time. Being aware of the political agenda and reasoning behind a war allows for more awareness of political and military alliances in order to achieve victory in war. In addition, by understanding that there are tactics and strategy which must be used in war a victory can be acquired (website, Handel). To Clausewitz this means that â€Å"preparations for War† and the â€Å"War itself† must be seen as distinct entities. By preparing for the War you are acquiring all needed provisions and equipment, and comprehending the enemy and terrain in which the battles might be fought (Clausewitz Book 6). Sun too indicates that preparation for War is strongly required, and that without it practicality of strategy is lost. This would include any tactics to be used, calculations which can done, deriving rules or â€Å"even systems for the conduct of war†, and understanding that knowledge can be â€Å"converted into real power†. Clausewitz considers that â€Å"war is science when mere knowing; art, when doing. † This law of action must include strategy. This in turn â€Å"links together the series of acts which are to lead to the final decision† or finality of victory. Because these strategic elements are key to achieving victory, this author insists that the â€Å"use of engagements†¦. be classified into: moral, physical, mathematical, geographical, and statistical† aspects. This elements manifest within the process and act of War, and encompass the idea that strategic assembly of forces enables victory. Clausewitz indicates that the use of battle leads to the destruction of the enemy’s military, and that a great results is achieved by battle (KLINGER 79-89).

Unemployment Rates in Australia

Unemployment Rates in Australia The key driver of poverty in Australia is unemployment. Unemployment rate is one of the economic indicators of the level to which Australian economy is operating to its full capacity. It defines the unemployment level divided by the labour force. Australia uses the standard definition of employment. The unemployment rate of Australia started increasing since World War I and II. Australia has taken great efforts to lower the unemployment rates all the time. The worst of the global recession was avoided by Australia but there was a steady increase in the unemployment since 2008. The strong effect of the fiscal stimulus package of Australia, tax cuts and public expenditure has cushioned the increase of unemployment created because of the global economic downturn. The working hours adjustments prevented large job losses, but this led to the growth of the discontentment in the workers. There was a quick rise in the youth unemployment rate. The bar chart shown above gives the present unemployment rates of the major economies in the world. When compared with unemployment rates of other major economies, we see the Australia has considerably lesser rate of about 5.3%. But this rise in the employment rate was less than the expected. This is one the lowest unemployment rates the country has had since the global economic recession hit Australia. The availability of the countrys resources and the global demand for them are believed to be the main reasons for the lowering of the unemployment rate from about 5.5 % (December). And this rate is less than the expected rate (5.6 %). The government reports shows that about 196,000 jobs were added by the Australian employers and about 16,000 full-time employees and additional 36,900 part-time workers are believed to have been hired to ease the unemployment rate. The trend estimates showing the recent monthly rates and figures of March 2010 related to the unemployment is given below:- There is an increase in the employment to 10,991,900 (ABS, March 2010) There is a decrease in unemployment to 611,000 (ABS, March 2010) The rate of unemployment is 5.3% (ABS, March 2010) The constant labour participation rate is maintained at 65.2%(ABS, March 2010) There is an increase in the aggregate monthly hours worked increased to 1,540.5 million hours(ABS, March 2010) The male employment rate is 5.4% and female unemployment rate is 5.3%.(ABS, March 2010) On a state breakdown, we see that there is a decrease in the unemployment rate eased in New South Wales from 6.8 % in March to 6 % in April. Victoria remained constant at 5.6 %, increase in Queenslands rate by 0.1 % to 4.9 %; fall in South Australias rate from 5.9 % to 5.5 %, and a drop in Western Australias rate from 4.9 % to 4.5 %. The small decrease in the unemployment rate has help to increase the growth in the Gross Domestic Product (GDP) of Australia. This increases the output of the companies. The increase in the GDP has led to the increase in the price of the goods and services and this has led to the increase in the inflation rate. But, the Australian economy has a tendency to continue in an ongoing cycle of this and will continue in the future. It has been seen that staff retention issues or problems have occurred due to the low unemployment rate of Australia with important effects of business. A latest survey conducted by Drake Edwards, Strategic Manager of Drake international commenting (March 2010), has identified several areas of staff retention. The findings are:- About 80% of employees give much importance in having a challenging and a very satisfying work in order to continue their work; and 75 % gives importance to better work life balance, career development opportunity and better management and leadership; and comparatively less percentage of employees gives importance to increased salary in Australia. (Article: Unemployment rate unchanged at 5.3 %, by David Olsen on Thursday, 8 April 2010) The lowering of the unemployment rate has led to economic growth and wage growth and increase in the aggregate demand. That is, the deficient aggregate demand and the real wage growth predominantly produce changes in the unemployment. MEASURES TAKEN BY AUSTRALIAN GOVERNMENT TO REDUCE UNEMPLOYMENT The main strengths of the macroeconomic frameworks and the Australian governments commitment to well-functioning markets are its high labour force participation, low unemployment, and the solid productivity growth. The constant sustainable economic growth can only be achieved with stable and low unemployment and inflation. These outcomes can only be supported by a sound macroeconomic policy frame work for fiscal and monetary policy. The fiscal policy has great impact on the economic activity and employment. The political factors in the allocation of funds indirectly do affect the unemployment rate. For example, programs such as Roads to Recovery program during the period of Australian election in 2001-04 has improved the local economic activity and has reduced unemployment to an extent. This led to a decrease in the local area unemployment rates (Leigh, 2008). The introduction of such programmes is being utilized to reduce the unemployment rate in Australia. Government always maintain budget balance over the course of economic cycle, takes into account the fiscal risks, national saving adequacy, the financial effect of policy decisions in future generations and the integrity and stability of the tax system in order to attain sustainable economic growth which will reduce the unemployment. The government has placed emphasis on the policies that raise the labour force participation. Some of the policies are the introduction of the welfare to work package that has measures to reduce reliance on the welfare and increase incentives to enter the workforce. Personal income tax cuts with the marginal tax rates cuts and increased thresholds, the Family tax benefit changes have also increased the returns to work. Some measures are the recent superannuation reforms; labour market reforms to improve the labour market flexibility to reduce structural employment, introduction of labour market programmes and training programmes and the introduction of the mature age worker tax offset have improved the work incentives for the old people. Some policies are microeconomic reforms that improve resource allocation among industries and firms for output maximisation that improve efficiency and productivity of producer. They are introduction of industry reforms that provide innovation that i ncrease productivity and growth by improving efficiency growth and job creation; and taxation reforms. The Council of Australian Governments had announced the National Reform Agenda (NRA) for the productivity growth and labour force participation and to bring human capital improvements. Several models are introduced to develop different policy options to reduce the unemployment in Australia. REFERENCES: http://www.treasury.gov.au/documents/1239/HTML/docshell.asp?URL=02_Part_1.htm http://www.tradingeconomics.com/Economics/Unemployment-rate.aspx?Symbol=AUD http://www.bukisa.com/articles/101336_economic-policies-to-reduce-unemployment http://www.tradingeconomics.com/World-Economy/Unemployment-Rates.aspx http://www.ibtimes.com.au/articles/20100211/global-economic-recession-unemployment-rate.htm http://www.abs.gov.au/ausstats/[emailprotected]/mf/6202.0 http://www.abs.gov.au/AUSSTATS/[emailprotected]/mf/6202.0?opendocument#from-banner=LN

Evolution Of Speaker Manufacturing English Language Essay

Evolution Of Speaker Manufacturing English Language Essay A speaker is an electrical device that converts electrical signals to mechanical motion in order to create sound waves. A transducer, which is another name for a speaker, is a device that converts one form of energy to another. The speaker moves in accordance with the variations of an electrical signal and causes sound waves to propagate through a medium such as air or water. The first electrical speaker, patented by Alexander Graham Bell in 1876, was for the earpiece of the telephone. This design was later improved upon by Ernst Siemens and Nicola Tesla in 1877 and 1881 respectively. Siemens and Tesla used a metal horn driven by a membrane attached to a stylus to create the design of what would be the basis for the modern speaker. Thomas Edison was working on a design at this time using compressed air as the amplifying mechanism. He quickly found this was not the most effective way to create the mechanical waves that produce sound. He quickly withdrew his application for a patent an d settled on the metal horn design. The metal horn speaker is a speaker which can be found on antique record players. Metal Horn Speaker Moving Coil Speaker The modern design of the moving coil driver was established by Oliver Lodge in 1898. Lodge was a British physicist and writer that was involved in many key patents involving wireless telegraphy. In 1915, Magnavox emerged as the first public company to produce a loudspeaker. This design was the first practiced use of the moving coil drivers in a loudspeaker. Magnavox was started in that same year by Edwin Pridham and Peter L. Jensen. The companys focus was on developing consumer electronics. They would later go on to be the first to develop a phonograph loudspeaker. Today Magnavox is owned by one of the world leaders in electronics, Phillips. In 1924, Chester W. Rice and Edward W. Kellogg received the first patent on the moving-coil principle, direct radiator, and loudspeaker. Their patent was different from the previous attempts because of the adjustment of mechanical parameters in their design. The fundamental resonance of the moving system takes place at a lower frequency than that at which the cones radiation impedance becomes uniform. In 1926, Rice and Kellogg sold the loudspeaker, Radiola which was superior to anything else previously invented because it decreased sound distortion and improved audio quality for the buyer. These speakers used electromagnets instead of large powerful magnets in their design. The electro magnets were used because larger, more powerful magnets were not available at a cheap enough price at the time. In the 1930s, manufactures began placing two or three band passes worth of drivers in their speakers, which allowed for increased quality, sound pressure levels, and frequency response. Many of the components involved in the production of modern speakers have been improved upon from their initial designs. The biggest improvements have occurred mainly in the makeup of the materials in the speaker and in the enclosure design. The diaphragm materials and permanent magnet materials are some of the other speaker components which have improved throughout the years. With the advent of computer aided design and increased accuracy in measuring techniques, the development of the speaker and quality of sound have grown exponentially in recent years. The modern loudspeaker has a similar makeup to that of earlier designs, but some of the basic ideas behind the design have changed to give us the speaker we have today. The Modern Speaker Modern speakers use a permanent magnet and an electromagnet to induce the reciprocating motion of the diaphragm. The alternating current going through the electromagnet constantly reverses the magnetic polarity of the coil thus reversing the forces between the voice coil and the permanent magnet. This causes a rapid back and forth motion of the coil resembling that of a piston. When the coil moves it causes the diaphragm to vibrate the air in front of the speaker, creating sound waves. The frequency and amplitude of the electrical audio signal dictates the rate and distance that the voice coil moves thus determining the frequency and amplitude of the sound waves produced by the diaphragm. Drivers are only able to create sound in a given range of frequencies, thus many different types of drivers must be manufactured to account for the wide range of possible frequencies. The main components of the modern speaker are the diaphragm, permanent magnet, suspension, voice coil, and basket with three other important features being coaxial drivers, speaker enclosures, and audio amplifiers. In the following sections we will break down each component and investigate the improvements of each component including those in the material selection and the manufacturing process. Diaphragm One of the main components of a speaker is the diaphragm, sometimes called a speaker cone. The diaphragm can also be referred to as the diaphragm and its surrounding assembly including the suspension and the basket. However for our purposes the suspension and the basket will be individually discussed in later sections. Movement of the diaphragm causes sound waves to propagate from the speaker thus producing the noise we hear. The ideal properties of a diaphragm are minimal acoustical breakup of the diaphragm, minimal standing wave patterns in the diaphragm, and linearity of the surrounds force-deflection curve. The diaphragm stiffness and damping qualities plus the surrounds linearity and damping play a crucial role in reproducing the voice coil signal waveform. Eighty five percent of the diaphragms sold worldwide are made of cellulose fibers because they can be easily modified by chemical or mechanical means to giving it a practical manufacturing advantage not found in other common diaphragm materials, although reproducibility can be a problem. The lack of reproducibility can affect imaging, depending on the precision and quality of production. Cellulose is also advantageous over other diaphragm materials because of its low cost to produce. Although Cellulose works well as a diaphragm, new synthetic materials are emerging that are more lightweight, allowing for better audio quality, reduced distortion, and increased vibration and shock durability. These materials include polypropylene, polycarbonate, Mylar, silk, fiberglass, carbon-fiber, titanium, aluminum, aluminum-magnesium alloy, and beryllium. Polypropylene is the most common plastic material used in a diaphragm. The polypropylene is normally mixed with a filler, such as Kevlar, to reduce the manufacturing costs or it can be to alter the mechanical properties of the diaphragm. Polypropylene diaphragms have been increasingly more popular with the advancements in modern adhesive technology. Although with all plastic materials present, the material tends to have a viscoelastic creep, which is the materials tendency to slowly deform and stretch when under repetitive stresses. However, polypropylene diaphragms are still a popular choice for high performance speakers due to their consistent performance. Research is presently underway in attempts to create new plastic based materials such as TPX, HD-A, HD-I, Neoflex, and Bextrene for diaphragms. These materials generally have the same characteristics as polypropylene so the manufacturing costs cannot be justified for full production. Another option for low-frequency applications are woven fiber diaphragms. The woven fibers such as carbon fiber, fiberglass, and Kevlar are bonded together with a resin. When the high tensile strength of the woven fibers mixes with the adhesive and bonding characteristics of the resin it results in an incredibly stiff material. This stiffness results in a great low-frequency diaphragm, however the stiffness causes rough high-frequency responses. There have been numerous attempts to improve the high-frequency problems of woven fiber diaphragms such as using two thin layers of Kevlar fabric bonded together with a resin and silica microball combination and another attempt employed a sandwich structure of materials with a honeycomb Nomex core. But again, as with the advanced plastic materials, the cost of manufacturing versus the performance of the material cannot yet be justified. The final modern practical material for diaphragms is metal. Metals worst downfall is its terrible damping attributes which causes extreme high-frequency distortion. The most common metal of choice are aluminum and magnesium alloys. Due to the lack of technological advances in damping agents to add to these alloys, metal diaphragms are very rarely used in high-frequency applications. However, these alloys have been commonly used in lower end frequencies with great success. Permanent Magnet Modern driver magnets have become predominately permanent magnets. Historically this function was filled by the use of electrically powered field coils. When high-strength permanent magnets became available, they eliminated the need for the additional power supply that drove the coils. When this happened, Alnico magnets became popular. Alnico magnets are created from alloying aluminum, nickel, and cobalt. Until about 1980 Alnico magnets were primarily used but because of their tendency to become demagnetized, permanent magnets have since been made of ceramic and ferrite materials. Ferrite magnets are constructed by mixing iron oxide with strontium and then milling the compound into a very fine powder. The powder is then mixed with a ceramic binder and closed in a metal die. The die is then placed in a furnace and sintered to bond the mixture together. Sintering is the process in which the particles of the powder are welded together by applying pressure and heating it to a temperature below its melting point. Although the magnetic strength to weight ratio of ferrite magnets is lower than Alnico, it is considerably less expensive, allowing designers to use larger yet more economical magnets to reach a desired performance. In manufacturing, the most significant technical innovation of the speaker is due to the use of neodymium magnets. Currently neodymium magnets are the strongest permanent magnets known to man. For this reason neodymium magnets significantly help in producing smaller, lighter devices and improve speaker performance due to their great capacity for generating strong magnetic fields in the air-gap. A neodymium magnet is an alloy of neodymium, iron, and boron to form the molecule Nd2Fe14B. The molecular structure of this molecule is a tetragonal crystalline structure. Important properties in a magnet are the strength of the magnetic field, the materials resistance to becoming demagnetized, the density of magnetic energy, and the temperature at which the material loses its magnetism. Neodymium magnets have much higher values for all of these properties than other magnetic materials except that it loses its magnetism at low temperatures. For this reason it is sometimes alloyed with terbium and dysprosium in order to maintain its magnetic properties at higher temperatures. Suspension Another critical element in speakers is the suspension. The purpose of a suspension system is to provide lateral stability and make the speaker components return to a neutral point after moving. A typical suspension system includes two major components, the spider and the surround. The spider connects the voice coil to the frame of the speaker and provides the majority of the restoring force. The surround connects the top of the diaphragm to the frame of the speaker and helps center the diaphragm and voice coil with respect to the frame. Both components work together to make sure the diaphragm and coil assembly move strictly linearly and in line with the center of the permanent magnet. The spider is usually made of a corrugated fabric disk, impregnated with a stiffening resin. The name comes from the shape of early suspensions, which were two concentric rings of Bakelite material, joined by six or eight curved legs. The surround may be resin treated cloth, resin treated non-wovens, polymeric foams, or thermoplastic elastomers that are molded onto the cone body. An ideal surround has sufficient damping to fully absorb vibration transmissions from the cone to surround interface, and the durability to hold out against long term fatigue caused by prolonged vibration. Advancements in suspension manufacturing have come from innovations in synthetic suspension materials. The use of synthetic materials like kevlar or konex instead of cotton, has made todays speakers much more stable than those made as recent as ten years ago. A more durable suspension means that a speakers sound quality can remain unaltered for a longer period of time. This is especially a concern for speakers that generally operate at low frequencies since lower frequency sounds are created by larger diaphragm travel and larger diaphragm travel must be supported by more suspension travel. Voice Coil The wire in a voice coil is usually made of copper, though rarely aluminum and silver may be used. Voice coil wire cross sections can be circular, rectangular, or hexagonal, giving varying amounts of wire volume coverage in the magnetic gap space. The coil is oriented co-axially inside the gap; it moves back and forth within a small circular volume (a hole, slot, or groove) in the magnetic structure. The gap establishes a concentrated magnetic field between the two poles of a permanent magnet, the outside of the gap being one pole, and the center post (called the pole piece) being the other. The pole piece and backplate are often a single piece, called the poleplate or yoke. This magnetic field induces a reaction with the permanent magnet causing the diaphragm to move thus producing the sounds we hear. Voice coils can either be overhung, longer than the magnetic gap, or underhung, shorter than the magnetic gap, depending on its application. Most voice coils are overhung thus preventi ng the coil from being overdriven, a problem that causes the coil to produce significant distortion and removes the heat-sinking benefits of steel causing the speaker to heat rapidly. The most important characteristic of a voice coil is that it be able to withstand large amounts of mechanical stresses and also be able to dissipate heat to its surroundings without causing damage to the speakers other components. In early loudspeakers the voice coil was wound onto paper bobbins to remove heat from the system. At the time this was enough to cool the system at average power levels but as larger amplifiers became available allowing for higher power levels new technologies had to emerge. To cope with the increasing power inputs the use of alloy 1145 aluminum foil was widely used as a substitute for the paper bobbins. Aluminum was popular to industry due to its low cost to manufacture, its structural strength, and it was easy to bond to the voice coil. However, problems with the foil emerged over extended use at increased power levels. The first problem was the foil tended to transfer heat from the voice coil into the adhesives used inside the speaker causing them to thermally degrade or even burn. The second problem was the motion of the aluminum foil inside the magnetic gap created currents that actually increased the temperature of the voice coil, thus causing long-term reliability issues. In 1955 a new material was developed called Kapton, a polyimide plastic film, to replace the aluminum foil. Kapton solved all the problems that were associated with the aluminum foil however Kapton or even its improved cousin Kaneka Apical, were not perfect. Both high-tech materials were costly to manufacture and had a tendency to soften when heated. Although Kapton and Kaneka Apical had their downfalls they became the most widely used coating for voice coils until 1992 when a material called Hisco P450 was developed. Hisco P450 is a thermoset composite created by using a thin film of fiber glass cloth and impregnating it with a polyimide resin. This combination allowed for necessary mechanical strength and endurance of the polyimide and necessary temperature resistance and stiffness of fiberglass. Hisco P450 was able to withstand the grueling temperature requirements of professional speakers while also maintaining enough rigidity to withstand the mechanical stresses associated with long-term, high-frequency motions. In recent years the copper wire that is almost always used as the voice coil has been replaced sparingly with aluminum wire in extra sensitive, high-frequency applications. The aluminum wire is lighter than the copper wire and has about two thirds of the electrical conductivity allowing the wire to move at higher frequencies inside the magnetic gap. Variations of the aluminum wire include copper-clad aluminum and anodized aluminum. Copper-clad aluminum allows for easier winding along with an even more reduced mass. The anodized aluminum is effectively insulated against shorting which removed the concerns of dielectric breakdown. Aluminum wires are great lightweight, low-inductance choices for voice coils however, they do have their downfalls. The thermal characteristics of aluminum causes power limitations with the coil. If too much power is passed through the aluminum coil it can cause the adhesive bonds between the wire and the bobbin, or the bobbin to the spider and coil to weaken or even burn. To cope with the ever increasing power demands on the voice coil in addition to wrapping the coil in some high-tech material to increase its thermal properties, the voice coil has also been submerged in a ferrofluid, an oil that is used to conduct heat away from the voice coil and also creates a small magnetic field thus increasing the power handling capacity of the voice coil. Basket The basket or frame (as seen below) is the fixture used to hold the diaphragm, voice coil, and magnet in the proper place. The rigidity of this part is extremely important to prevent rubbing of the voice coil and prevent random movements that could cause problems with the permanent magnet. The three most common types of modern baskets are cast metal baskets, rigid baskets made out of stamped steel or aluminum, and cast plastic baskets. Each type of basket offers different advantages and disadvantages; these will be discussed in the flowing paragraphs. The stronger the basket the more power the speaker can handle before failure occurs. A well made basket should have a high power rating, be lightweight, and be able to conduct heat away from the voice coil to prevent physical changes or even possible demagnetization of the permanent magnets. Cast metal (above right) baskets are the most rigid of the three in all directions, but they are the most expensive to make. Cast metal baskets are made by melting down the desired metal to liquid form. The scorching hot liquid metal is then poured into a mold and once the liquid metal dries inside the mold, the mold is removed revealing a cast metal basket. Cast metal baskets although more expensive than the other two options, usually are more rigid thus preventing motion. They also have better damping characteristics, and they are also more easily manufactured allowing for more intricate shapes. Cast metal baskets are usually the preferred basket choice for higher quality speakers. A less expensive and yet less rigid basket can be made out of stamped steel. The stamped steel or aluminum sheets arrive to the manufacturer preformed. The sheets are then drilled using a hydraulic press to cut holes in the sheet to allow air flow to and from the diaphragm. The sheet is then pressed using another hydraulic press using a die to form the desired shape. Stamped metal baskets tend to be weaker than their cast metal counterparts. This weakness could cause the basket to flex if the speaker is being used at high volumes. The final option, which is even less expensive, is a cast plastic basket. Cast plastic baskets are made by using the liquid plastic and pouring it into the desired shaped mold. When the liquid plastic dries the mold is removed revealing a cast plastic basket. Just like cast metal baskets, cast plastic baskets are easily manufactured allowing for intricate shapes. The lightweight characteristics of the plastic would also make the speaker lighter allowing for smaller power consumption. However, as with most engineering decisions, the performance of the part proportionally decreases as the cost to produce the part decreases. The decreased cost of production of the plastic basket means that it is a weaker basket. This weaker, plastic basket will allow for the most flexing as compared to cast metal and stamped steel baskets. The power rating of the speaker would also be less than that of the metal baskets, both cast and stamped, due to the weaker strength characteristics of plastic in com parison with metal. Coaxial Drivers Coaxial drivers are the components of a speaker that radiates sound from the same point or axis. This is done by placing a high-frequency driver in the center of a low-frequency driver so that they produce sound waves from a single point in a loudspeaker system rather than separate locations. This allows for a more beneficial design over having the low and high frequency drivers separate. There are many different types of drivers and each driver produces sound within a limited frequency range. Subwoofers, woofers, mid-range drivers, and tweeters are all driver types capable of emitting different ranges of sound. A coaxial driver takes one of these higher frequency drivers and places it within a lower frequency driver. For example, a tweeter, the high frequency unit, could be placed in the center of a woofer, the low frequency unit, so that both drivers emit sound from the same point. This example can be seen in the images below. This design, which improves sound quality, was first de signed by Altec Lansing in the 1940s. Although it has many advantages, it is still an uncommon practice in the manufacturing of speakers due to technical and budgetary considerations. Enclosures The enclosure of a loudspeaker serves three functions and is made with a specific design that helps improve the quality of the sound produced by the speaker. The first function the enclosure performs is separation of the sound waves. It accomplishes this by preventing sound waves generated at the back of the speaker from interacting destructively with sound waves generated at the front of the speaker. The enclosure is intended to reduce distortion created because the waves that emanate from the front of the speaker are out of phase with the waves emanating from the rear of the speaker. If the front and rear waves were to overlap with one another it would result in wave interference. The second function the enclosure serves is to stop any echo and reverberation that would be created from the two differing sound source locations on the speaker. Because waves are created at the front and rear of the speaker, the two different sets of waves travel through the air differently as a result of their relative locations, and arrive at the person listening at different times. The third function the enclosure serves is to deal with the vibrations produced by the driver and to deal with the heat produced by the electronic components. Enclosures did not always have the fully enclosed container design that they now commonly have. Although present day practices say that enclosures need to have a back, before the 1950s they lacked one due to the cooling functions of an open container. Sealed enclosures, the most common type of enclosure, is completely sealed so no air can escape. With this type of enclosure the forward wave travels outward into the surroundings, while the backward wave is limited to only fill the enclosure. With a virtually airtight enclosure, the internal air pressure is constantly changing; when the driver retracts, the pressure increases and when the driver moves out, the pressure decreases. Both movements create pressure differences between the air inside the enclosure and the air outside the enclosure. Because of this, the driver motion always has to fight the pressure differences caused. These enclosures are less efficient than other designs because the amplifier has to boost the electrical signal to overcome the force of air pressure. The force due to air pressure does, however, provide an additional form of driver suspension since it acts like a spring to keep the diaphragm in the neutral position. This makes for tighter, more precise soun d production. Enclosure designs range from very simple, rectangular particle-board boxes (above left) to very complex cabinets made of composite materials (above right). The simplest enclosures are made to prevent destructive interference caused by overlapping of the front and rear sound waves from the speaker. The most complex enclosures contain acoustic insulation and internal baffles, which prevent interference. Solid materials such as heavy wood, are typically used when building enclosures in order to absorb the vibration caused by the speaker driver. This vibration dampening is extremely important. A speakers sound output would be drowned out by the drivers vibrations if there were not an enclosure incorporated into the design. Since the beginning of the production of enclosures, the most advantageous properties required for minimal energy loss through the enclosure walls have remained unchanged. Different strategies employed to reduce energy losses are to use thicker enclosure walls, denser hardwood plys and sturdier bracing. The downside to these methods is that they all add significant weight to the enclosure. However, with the production of newer materials that possess an increased stiffness-to-mass ratio this is changing. These new materials can improve performance and reduce weight, while also reducing the cabinets resonance. The end result is that a greater amount of the speakers en ergy is delivered in the intended direction rather than into mechanical vibrations which are wasted and produce a decrease in sound quality. A recent alternative to heavy wood construction of enclosures is the use of composite materials. It was for the aerospace industry that composite materials such as carbon-fiber were originally developed. Carbon-fiber was a success because of the high demand for a material with increased strength and rigidity. Speaker applications, such as enclosures use carbon-fiber materials to create a product with a vastly decreased weight and increased strength and rigidity. Enclosures built with carbon-fiber can weigh less than half as much as enclosures built from heavy wood. These enclosures which limit the speaker resonance can provide as much as 3 dB more output than the same speaker would have otherwise had in a heavy wood enclosure. Furthermore, carbon-fiber enclosures are extremely durable adding quality to the final product and they require almost no maintenance. Even though carbon-fiber enclosures cost around twice as much to produce as traditional enclosures, the lighter weight and ext ra output offer two very advantageous tradeoffs. Amplifier An amplifier is any device that increases or decreases the amplitude of a signal. An audio amplifier increases low-power audio signals to a suitable level for loudspeakers. When dealing with a speaker there are a many audio amplifiers involved. These amplifiers are responsible for pre-amplification, equalization, tone control, and mixing effects followed by a higher power amplifier which creates the final amplification for suitable levels of sound output. Amplifiers are found in wireless receivers and transmitters, CD players, acoustic pickups, and hi-fi audio equipment. Amplifiers are used for high-quality sound production, and depending upon the quality of the amplifier, they may cause distortion, which the speaker enclosures are meant to deal with. Distortion in amplifiers is caused by difference in phases of the output waveform and the input waveform. The smaller the difference in between the output and input waveforms the greater the quality of final sound. Audio amplifiers cons ist of resistors, capacitors, power sources, wires, semiconductors, and stereo jacks all combined on an electronic work board to produce the type of amplifier needed. Types of Speakers Woofers are loudspeaker drivers designed to produce sounds of low frequency from around 40 hertz up to around 1000 hertz. The most common design for a woofer is the electro-dynamic driver, using a stiff paper cone driven by a voice coil. Woofers are important to allow for a range of frequency that will hit a low level. Effective woofer designs efficiently convert low frequency signals to mechanical vibrations. The vibration of the air out from the cone creates concentric sound waves that travel through the air. If this process can be done effectively, many of the other problems speakers run into will be greatly reduced such as linear excursion. For most speakers the enclosure and the woofer must be designed to work hand in hand. Usually the enclosure is designed around the woofer, but in some rarer cases the enclosure design can actually dictate the woofer design. The enclosure is made to reflect the sounds at the right distance, so that they will not be wave cancelling reflections. Below you can see an example of a common woofer. A subwoofer is a woofer with a diameter between 8 and 21s. Subwoofers are made up of one or more woofers. They can be arranged in many different configurations to produce the best quality of sound. Subwoofers usually play frequencies between 20 hertz and 200 hertz, well within the range of human auditory levels. The first subwoofer was created in the 1960s and added to the home stereo to create bass for sound reinforcement. Up until this point the only form of audio player which contained bass was a phonograph player which was created by Magnavox. This allowed for a more accurate array of music. Subwoofers are used in all sound systems today such as in cinemas, cars, stereos, and for general sound reinforcement. A mid-range speaker is a loudspeaker driver that produces sound between 300 hertz and 5000 hertz. These are less commonly known as squawkers. Midrange drivers can be found as cone speakers, dome speakers, or compression horn drivers. Mid-range speakers usually resemble small woofers. The most common material the cone is made out of for a mid-range is paper although they can be found to be coated or impregnated with polymers or resins to improve vibration dampening. Much of the rest of the mid-range speaker is made from plastic polymers. Mid-range speakers which employ the dome set up usually only use 90 degrees of the sphere as the radiating surface. These can be made from cloth, metal or plastic film. The voice coil in this design is set at the outer edge of the dome. Mid-range drivers are most commonly used for professional concerts and are compression drivers coupled with horn drivers. Rarely mid-range speakers can be found as electrostatic drivers. Mid-range speakers handle the most prominent part of the human-audible sound spectrum. This is the region where most sound emitted by musical instruments lie. This is also where the human voice falls in the audible spectrum. Most television sets and small radios only contain a single mid-range driver. Tweeters are a loudspeaker designed to produce frequencies from 2,000 to 20,000 hertz. Some tweeters on the market today can produce sounds of up to 45000 hertz. The human ear can generally only hear up to about 20000 hertz. The name tweeter comes from the extremely high pitch it can create. Modern tweeters are different from older tweeters because older tweeters were smaller versions of woofers. As tweeter technology has advanced, differen

Analysis of First To Fight Essays -- Book Review, Military History

First To Fight begins with Krulak engaged in a conversation with a Gunnery Sergeant who was asked how the Marine Corps got the reputation of having one of the world’s greatest fighting formations. The GySgt replies â€Å"Well lieutenant they started telling everybody how great they were and pretty soon they started believing it†. The story goes on to talk about how there nearly wasn’t a Marine Corps. starts out with Marine Lieutenant General Holland M. Smith on the bridge of the command ship Mt. Olympus, off Iwo Jima on the morning of 23 February 1945 with Secretary of the Navy James Forrestal who said that the raising of our flag atop Mt. Suribachi means there will be an Marine Corps for the next five hundred years. Smith commented â€Å"When the war is over and money is short they will be after the Marines again†, and a dozen Iwo Jimas would make no difference. The resolute general was voicing the frustrations of the many generations of Marines before him who had learned through hard experience that fighting for the right to fight often presented greater challenges than fighting their country’s enemies. The Marines’ survival struggles during their first century and a half were mere skirmishes compared with what was to commence following the Second World War. Even as America was still trying to see through the smoke of Pearl Harbor, there were problems which were seen that were far more serious. A carefully designed plan which, if implemented, would destroy the Marine Corps as a fighting force. The scene was set according to Krulak by three events. In early October 1942 Krulak was a member of a team of four Marine officers assigned to the Army’s 25th Infantry Division at Schofield Barracks, Hawaii to conduct instruction for the divisi... ...states there are three powerful external factors that cloud the Marines’ horizon. The first being the oppressive influence of threat. That threat is rooted in the attitudes or aspirations of the Army, the Navy, or various chief executives. Its nature has varied-threat to the Corps’s repute, to its right to fight, to its very survival. Secondly, the recurrent military affliction called austerity. At worst, they linger in active service and are a hazard to all around them. The third is the dead hand of bureaucracy that lies over the entire military establishment. While the larger services may be able to handle the pressures of bureaucracy, the Marine Corps has neither the instinct nor the time for it. The Marines are an assemblage of warriors, nothing more. Paper massaging and computer competitions do not kill the enemy, which is what the Marines are supposed to do.

Girls and Selfie Culture: Empowering or Narcissistic? Essay -- self-est

Art, specifically the self-portrait, has evolved along with technology and social media. With the technological generation, the self portrait has become a selfie. But what sort of social implications come along with this new trend? Thesis Statement: Selfies give women and girls the power to represent themselves the way they wish to be seen, boost self-esteem, and could even shift the standard of beauty to something more realistic. How Selfies got Started In any art history class, there is one topic that is always covered: the self-portrait. All great artists from Leonardo Da Vinci to Jackson Pollock have immortalized themselves in the form of autobiographical portraiture. Female self portraits are specifically significant. Until the 20th century, women were rarely trained in the art of painting. Usually, the only female artists were the daughters of male artists. This was because it was necessary for apprentices of artists to live and work with the senior artist. Of course, it was socially unacceptable for a woman to live with a man to whom she was not married. Therefore, most portraits of women pre-20th century are not self portraits, but instead portraits painted by male painters. We can recognize these portraits by the fact that the subject’s gaze is never at the viewer, but rather to the side or downwards, due to the fact that women were not meant to look men in the eye. One female artist pre-20th century who created a famous self-portrait is Marie-Denise Villers. Her most famous painting, Young Woman Drawing, was once thought to be the work of Jacques-Louis David. According to the Metropolitan Museum of Art, â€Å"many paintings, especially portraits of young women, which were formerly attributed to Jacques Louis David or... ...pinto, Lauren. "Artist Selfies: Everybod'ys Doing It." Muddy Colors (blog), January 23, 2014. http://muddycolors.blogspot.com/2014/01/artist-selfies-everybodys-doing-it.html (accessed March 3, 2014). Ryan, Erin Gloria. "Selfies Aren't Empowering. The'yre a Cry for Help.." Jezebel (blog), November 21, 2013. http://jezebel.com/selfies-arent-empowering-theyre-a-cry-for-help-1468965365 (accessed March 1, 2014). Simmons, Rachel. "Selfies Are Good for Girls." Slate (blog), November 20, 2013. http://www.slate.com/articles/double_x/doublex/2013/11/selfies_on_instagram_and_facebook_are_tiny_bursts_of_girl_pride.html (accessed March 1, 2014). Winter, Jessica. "Selfie-loathing." Slate (blog), July 23, 2013. http://www.slate.com/articles/technology/technology/2013/07/instagram_and_self_esteem_why_the_photo_sharing_network_is_even_more_depressing.html (accessed March 1, 2014).

Choice theory

The term choice theory has originated from the work of Dr. William Glasser, MD, an American psychiatrist from Cleveland, Ohio; and which was popularized through his book of the same title released in 1998. Choice theory is the culmination of Glasser’s research work on psychology and counseling spanning 50 years. It used to called control theory, and is the foundation of Glasser’s Reality Therapy, a particular approach used in psychotherapy and counseling which was developed in the 1960’s. This approach focuses on the present emotional status of a person and the possible ways on creating a better future, instead of concentrating on his past.Reality therapy establishes a person’s ability in making decisions, taking actions in his life, and being able to control his life. This approach allows a person in discovering what they really want in their lives, and learns whether their current activities are actually leading them to their actual goals. Reality therap y has gained a decent following in the United States and is now widely used in the field of education. Choice theory considers that behavior is the center of human existence. Human existence is further determined by the five genetically driven needs, which includes survival, belonging, power, freedom, and fun.According to Maslow, survival includes man’s basic biological needs such as food, clothing, and shelter. The remaining four are the fundamental psychological needs. This theory considers that among the five, the most important need is love, or belonging, due to the fact that a person’s closeness to the people he love and care about is an essential factor in satisfying all the five needs. Choice theory also includes the â€Å"seven caring habits†: supporting, encouraging, listening, accepting, trusting, respecting, and negotiating differences.Against these habits are the â€Å"seven deadly habits†: criticizing, blaming, complaining, nagging, threateni ng, punishing, and bribing or rewarding in order to control. Choice theory and the seven caring habits are aimed to replace and counteract the so-called external control psychology and the seven deadly habits, which is believed to be the present state of mind of most people in the world. The seven deadly habits are believed to be destroying relationships because it ruins a person’s ability to find satisfaction in his relationship.This further results to people getting disconnected from the people they care about, and which would prove to be the cause of most problems in the society at present: illnesses, depression, substance abuse, and uncontrolled violence, and rising crime rates. Choice theory then presents ten axioms, and these are: 1. The only person whose behavior we can control is our own. 2. All we can give another person is information. 3. All long-lasting psychological problems are relationship problems. 4. The problem relationship is always part of our present life . 5.What happened in the past has everything to do with what we are today, but we can only satisfy our basic needs right now and plan to continue satisfying them in the future. 6. We can only satisfy our needs by satisfying the pictures in our Quality World. 7. All we do is behave. 8. All behavior is Total Behavior and is made up of four components: acting, thinking, feeling and physiology. 9. All Total Behavior is chosen, but we only have direct control over the acting and thinking components. We can only control our feeling and physiology indirectly through how we choose to act and think. 10.All Total Behavior is designated by verbs and named by the part that is the most recognizable. The idea of the existence of a â€Å"quality world† is presented by choice theory, which states that a person, beginning at birth and throughout his life, places everything important to him, including people, his beliefs, materials things, and other valuables into this world. The person then b ehaves throughout his life to achieve a real world based on his quality world. Related to the ideas of a person’s real and quality worlds is the â€Å"comparing place† where the real world is compared to the quality world.With the idea of â€Å"total behavior†, Glasser believes that among the four components, a person can only exert control over two, which are acting and thinking; and have limited capacity to influence the other two, feeling and physiology. As these four are interconnected, the manner by which a person acts and thinks has tremendous impact on his feelings and physiology. Glasser’s choice theory is one that is based psychology. The theory further states that most mental illnesses being experienced by most people in the world are caused by unhappiness.Mental illness is actually brought about by a person’s unhappiness and dissatisfaction in life. Although contested by most mainstream psychiatrists, Glasser’s theory is now used in a wider range of social issues including education, family, management, and mental health. His theories have gained popularity not only in the United States where they are most commonly used in education, but also in the global arena. Glasser’s choice theory is all about being able to choose how to live happily, how to make better decisions that satisfy a person’s need, how to responsibly take action, and how to take control of one’s life.This theory is all about living satisfactorily in order to lessen unhappiness, promote better relationships among people, and therefore eliminate mental illness in the world today. Sources: Furr, Lee W. and W. Hugh Furr. (2006, March 14). Choice Theory Psychology. [Electronic Document]. http://www. choicetheory. com/ The William Glasser Institute. (2006, May 11). Choice Theory. [Electronic Document]. http://www. wglasser. com/whatisct. htm Schneller, Peter L. (2005, August 30). Choice Theory. [Electronic Document]. http://ra ider. muc. edu/~schnelpl/Control Theory – Overhead. html

Notes on the Ethical Theories Essay

Immanuel Kant (notice that he lived in the 1700’s and people likely had different views back then), a philosopher, believes that using reason, one can make a list of ethical actions. Kant says that one must generalize the certain action he is about to do to see if it is reasonable. For example, you ask yourself â€Å"should I cut the line in the cafeteria?† The way you can answer this question is by asking yourself â€Å"What if everyone cut the line?† Of course, if that happened then there would be chaos, so you shouldn’t cut the line. This also applies to stealing, murdering, and keeping promises. He basically says that everyone is equal and you shouldn’t justify your actions to yourself because you are not special and you wouldn’t want others to do that to you. â€Å"Treat others as you would have them treat you.† Golden Rule. But, if only you do this and no one else does you are going to get eaten up by the world. This may contradi ct a person’s adaptability and may negatively appeal to emotion; you will feel like a B—-. Veil of ignorance- You have two people who love cake. Tell one person to cut a cake in half but let the other choose which half to take. Again, Golden Rule. Kant says there is a difference between objects and people, you can replace objects but not people. Someone broke my computer, I am sad. He buys me a new one, I am happy. I am about to die, my parents are sad. They can clone me, should they be happy? He also says that you shouldn’t kill people for the greater good. But what if they were murderers or rapists aren’t they causing sadness, and their deaths would in fact be for the greater good? Kant sees that a persons intentions that count rather than the final result. But what if I am helping a person, who is bad and corrupt, against a thief who is only trying to feed his family, quite the dilemma. Kant uses only reasoning rather than emotion so that people always do what is right rather than when they feel like it. Consistency is key to his theories. Criticisms of Kant Moral Absolutism – You can’t always not lie. What if a murderer wants to kill your dad? Your dad hides and then the murder breaks in and asks you were he is. If you follow Kant’s ideas, you would tell him where your dad is. There must be some sort of emotion to counteract those who do not follow the philosophy of Kant. But again, Kant is saying that EVERYONE should do this, and this murderer wouldn’t exist in Kant’s ideal world. Rule worship- To blindly follow rules without using your own knowledge. â€Å"If rules can not be bent, then they should be broken.† Conflicts of duty- should you steal the medicine for your dying wife? Should you save your grandmother from the burning house or the doctor who can save many people? Moral coldness- The world would be emotionless and sad. There will be little space for happiness because everything is going to be so constant and emotions will have a very small presence. Utilitarianism- Seek the greatest happiness for the greatest number. What if you could randomly pick 10 people to die and save 100? Would you do it? You can say yes, because it logical, you use no emotion what so ever. That goes against Kant though because he says that people have dignity and you shouldn’t take that away. You can say no, where you are mostly using emotion.