...Marxist theory has both informed community development and provided one of the most resonant critiques of it. Discuss Over the years Marxist theory has not only informed community development but it has also provided one of the most resonant critiques of it. To Marxism, the biggest critique of community development is that it is a mechanism for control to keep the working class in their place and in reserve for when their labour is needed. I will discuss the Marxist theories of alienation and struggles over mode of production and resource allocation, as well as how Western Marxism has shaped community development. In this essay I will also discuss how Marxist theory has identified that the working class are to be exploited by the bourgeoisie and the only way to improve society is to dismantle the capitalist society and install a socialist society. Marxist theory is based on Karl Marx’s theory of the struggle of the working class people selling their labour to the bourgeoisie – the capitalists – and their oppression by the welfare system. Marx believed that the rich bourgeoisie exploited the working class and the only way to stop this exploitation was to overthrow the capitalist system with socialism. The only real difference between capitalism and socialism is that private property rights and voluntary exchange define capitalism, whereas socialism is based around collective ownership of the means of production, which is owned by the state (Butgereit and Carden 2011...
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...Resonant Pulse Converters Chapter 11 (or 8) Prepared by Dr. Mohammad Abdul Mannan Assistant P f A i t t Professor, Department of EEE D t t f American International University - Bangladesh Disadvantages of PWM Controlled Switching Devices in Converters The disadvantages of PWM controlled switching devices in converters are as follows: 1. The devices are turned “on” or “off” at the load current with a high di/dt value, 2. The it h 2 Th switches are subjected t a hi h lt bj t d to high-voltage stress, t 3. The switching power loss of a device increases linearly with the switching frequency. 4. The electromagnetic interference (EMI) is produce due to high di/dt and dv/dt in the converter wave forms. The above mentioned disadvantages can be eliminated or minimized if the switching devices are turned “on” and “off” when th voltage across a d i and/or it current b h the lt device d/ its t becomes zero. The inverter in which the voltage and current are forced to pass through zero crossing by using an LC-resonant circuit is circuit, called calling a resonant pulse inverter. Classification of Resonant Pulse Inverters The resonant converters can be classified into eight types: 1. Series-resonant inverters, 2. Parallel-resonant inverters, 3. Class E resonant converters, 3 Cl t t 4. Class E resonant rectifiers, 5. Zero-voltage-switching (ZVS) resonant inverters, 6. Zero-current-switching (ZCS) resonant inverters, 7. Two-quadrant zero-voltage-switching (ZVS) resonant inverters...
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...Highly-Efficient Battery Chargers with ParallelLoaded Resonant Converters Ying-Chun Chuang e-mail:chuang@mail.ksu.edu.tw Yu-Lung Ke e-mail:yulungke@ms25.hinet.net Shun-Yi Chang e-mail:nickelayu@hotmail.com Department of Electrical Engineering, Kun Shan University, Tainan Hsien 71003, Taiwan, R.O.C. Abstract—The well established advantages of resonant converters for battery chargers, including fast response, low switching losses, easy of the control scheme, simplicity of circuit configuration, and low electromagnetic interference (EMI), among others, have led to their increasing attraction. This work develops a highly efficient battery charger with a parallel-loaded resonant converter for battery charging applications to improve the performance of traditional switching-mode charger circuits. The charging voltage can be regulated by varying the switching frequency. The switching frequency of the parallel-loaded resonant battery charger was set at continuous conduction mode (CCM). Circuit operation modes are determined from the conduction profiles. Operating equations and operating theory are also developed. This study utilizes the fundamental wave approximation with a battery equivalent circuit to simplify the charger circuit analyses and presents an efficient, small-sized, and cost-effective switched-mode converter for battery chargers. A prototype charger with parallel-loaded resonant converter designed for a 12V-48Ah battery is built and tested to verify the analytical...
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...| 3/5/2012 | | Mechanical Engineering Dynamics lab report.UFMEWL-10-2Vassos Tapakoudes | AIR TRACK Executive summary Demonstrate the patterns and relationships that stiffness and resonant frequencies follow under different circumstances on an air track. Stiffness is a measure of the resistance of a material to deformation under applied force. Resonant frequencies are the frequencies that a system appears to oscillate at greater amplitudes. Content Introduction pg.2 Theoretical calculations and background information pg.2 Experimental design and procedure pg.4 Analysis result and conclusion pg.7 Reflection to other experiment pg.9 Introduction The purpose of this dynamic Lab is to measure the stiffness and resonant frequencies of a coupled oscillator on an air track. Four experiments will be taken in order to see the behaviour and performance of the rubbers connecting the trolleys. Calculate theoretical results by using background information. Comparisons of theoretical and experimental results will be done to see errors and find conclusions. Resonant frequencies are the frequencies that a system oscillates at greater amplitudes. This type of oscillations is what makes systems to vibrate many times. On the other hand, stiffness is a measurement of the ability a material have to extend without deformation. Low stiffness can result in failure of a system and high stiffness is required in the design of systems that deformation...
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...IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL. 54, NO. 12, DECEMBER 2006 3755 A New Compact Microstrip-Fed Dual-Band Coplanar Antenna for WLAN Applications Rohith K. Raj, Manoj Joseph, C. K. Aanandan, K. Vasudevan, Senior Member, IEEE, and P. Mohanan, Senior Member, IEEE Abstract—A novel compact microstrip fed dual-band coplanar antenna for wireless local area network is presented. The antenna comprises of a rectangular center strip and two lateral strips miprinted on a dielectric substrate and excited using a 50 crostrip transmission line. The antenna generates two separate resonant modes to cover 2.4/5.2/5.8 GHz WLAN bands. Lower resonant mode of the antenna has an impedance bandwidth (2:1 VSWR) of 330 MHz (2190–2520 MHz), which easily covers the required bandwidth of the 2.4 GHz WLAN, and the upper resonant mode has a bandwidth of 1.23 GHz (4849–6070 MHz), covering 5.2/5.8 GHz WLAN bands. The proposed antenna occupy an area of 217 mm2 when printed on FR4 substrate . A rigorous experimental study has been conducted to confirm the characteristics of the antenna. Design equations for the proposed antenna are also developed. ( = 4 7) Index Terms—Coplanar waveguide, dual-band antennas, printed antennas, wireless local area networks (WLANs). I. INTRODUCTION IRELESS LOCAL area networks (WLAN) are being widely recognized as a viable, cost effective and high speed data connectivity solution, enabling user mobility. The rapid developments in WLAN technologies...
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...Oscillators Oscillator: An oscillator is a circuit that generates a repetitive waveform of fixed amplitude and frequency without any external input signal [1, p. 279]. Function of Oscillator: The function of oscillator is to generate alternating current or voltage wave forms such as sinusoidal, square wave, triangular wave, sawtooth wave, etc. Used of Oscillator: Oscillators are used in radio, TV, computers, CRT, Oscillocope, and communications. Types of Oscillator: There are two main types of electronic oscillator: (i) Harmonic oscillator and (ii) Relaxation oscillator Depending on the used elements of an oscillator, the types of oscillator are: (i) RC oscillator, (ii) LC oscillator and (iii) Crystal oscillator. Harmonic Oscillator: The harmonic oscillator produces a sinusoidal output. The basic form of a harmonic oscillator is an electronic amplifier with the output attached to a narrow-band electronic filter, and the output of the filter attached to the input of the amplifier. When the power supply to the amplifier is first switched on, the amplifier's output consists only of noise. The noise travels around the loop, being filtered and re-amplified until it increasingly resembles the desired signal. Relaxation Oscillator: The relaxation oscillator is often used to produce a non-sinusoidal output, such as a square wave, sawtooth wave, and triangular wave. The oscillator contains a nonlinear component such as a transistor that periodically discharges the...
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...Prospects Rachit Sethia Department of Electrical & Electronics Oriental Institute of Science & Technology Bhopal, India rachitsethia19@gmail.com Sahil Saxena Department of Electronics & Communication Lakshmi Narain College of Technology Bhopal, India saxena.sahil.16@gmail.com Abstract— In the present paper, wireless power transmission is shown as the righteous alternative for present day power distribution system. Various method of wireless power distribution system are acquainted which can be ramified for power distribution, showing electrodynamic induction as the befitting one. Many concepts, research papers, patents are available on wireless power transmission and are fruitfully materialized by Witricity by magnetic resonant coupling method. This paper is mainly concentrated on: 1. The most popular concept i.e. Electrodynamic induction. 2. Microwave transmission method. The paper also discusses the possible ways to get useful and practical results out of all research carried out so far elsewhere. Keywords- Wireless power transmission, Electromagnetic induction, Nikola Tesla, Witricity, Electrodynamic Induction. Introduction Our present power distribution system encompasses various losses and flaws which blemishes the same. Recent canvas have shown that existing power transmission system see a considerably high power loss that in 26-30% in developed countries and about30-40% in developing or underdeveloped countries. The primary reason for the losses...
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...57. Which of the following antennas receive signals in the horizontal plane equality well from all directions? A. Horizontal Hertz antenna B. Vertical loop antenna C. Vertical Yagi antenna D. A vertical antenna which is a quarter-wavelength long 58. If the length of a Hertz dipole is decreased A. its resonant frequency will be lowered its distributed inductance will be increased B. its distributed inductance will be decreased C. its resonant frequency will be increased D. its distributed capacitance between the antenna and ground will be increased. 59. A final amplifier of a radio transmitter draws 250 mA of plate current when the plate supply voltage is 1400 volts. If the plate circuit efficiency is 80% and the transmitter is connected...
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...transducer in order to better understand its characteristics and know which way to use it in this project. The piezoelectric firm transducer has a mass attached on the end of an elastic film. As an input the system response has the movement of the electrode end, and as the output it has the flexure of the firm which causes a voltage displacement used for analysis. This 2nd order high pass function is calculated and analyzed in this experiment by taking into account the mass, spring constant of the film and the friction due to air and plastic viscosity in the firm. For this reason the weight added to the transducer during the procedure was measured to be taken into consideration for the calculations. The ultimate goal is to calculate the resonant frequency as well as the damping ratio and create a Bode plot to show the behavior of the signal. Steps Taken 1. Piezoelectric transducer set up and measurement with a normal and extra mass added 1. 1 The piezoelectric film transducer was connected to the breadboard and jumper cables connected to each lead of the film.(Shown in Figure 1) 1. 2 The jumper cables were connected to the...
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...manmade conductors (i.e., wires)”. Much of the technology exploited in the current (and still-early) implementation of WET has precursors in 19th century research by engineering visionaries such as Nikola Tesla. Broadly, there are two categories of WET: far-field (FFET) and near-field energy transfer (NFET). As the grand majority of research and development lies with NFET, FFET will not be discussed. Among the reasons underlying the preference for NFET is that it is safer and incurs less energy loss during energy transmission than FFET. NFET is based on electromagnetic induction and relies on one of two non-radiative methods: inductive coupling and resonant inductive coupling. In inductive coupling, running an electric current through one coil induces an electric current in a second coil with which it is in physical contact. In resonant inductive coupling by contrast, voltage is only induced between two coils that are tuned to resonate at the same...
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...Gravitational waves: Understanding and Detection Final draft Physics 222 November 11, 1999 Aaron Astle Dan Hale Dale Kitchen Wesley Krueger Abstract Gravitational waves carry information about catastrophic events in the universe. We give a brief description of gravitational waves with an overview of the current projects underway to detect them. We begin by discussing the theoretical prediction of gravitational waves from Einstein's General Theory of Relativity. We list several possible sources of these waves and describe how they produce gravitational waves. We also discuss the characteristic signals each source sends to Earth. We outline advantages and challenges for several detection methods now being implemented. These include resonant mass detectors and laser interferometry. We also discuss improvements being made to each system and how these improvements further our progress towards detection of the waves. Finally, we conclude with a prediction that laser interferometry will first detect these waves within the next few years. In 1905 Albert Einstein presented his Theory of Special Relativity with two postulates that led to a new realm of reasoning and observing the universe. Eleven years later Einstein extended these postulates to form the General Theory of Relativity. This theory predicts the existence of gravitational waves and describes properties these waves must have. If such gravitational waves could be detected, they could reveal much about the physics...
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...objective is to use this field to light up florescent light placed at some distance and because of the fact that it is an electric field that goes directly into the light and doesn't use the electrodes; even burned-out florescent lights will glow. The significant part of our proposed plan is that power is transferred wirelessly. The field produced is without any radiations and hence is harmless to human beings. I. Introduction Nikola Tesla invented the Tesla Coil, a type of air-cored resonant transformer, which is used to generate high voltage and high frequency electrical currents. Tesla coils are used to produce high-voltage, low-current, and high-frequency alternating-current. It can produce higher voltages than other artificial sources of high-voltage discharges and electrostatic machines. It takes the output from a 230vAC to several kilovolt transformer & driver circuit and steps it up to an extremely high voltage. II. Basic Scheme of Tesla Coil A Tesla coil is a resonant transformer containing a primary and a secondary LC circuit. The two LC circuits are loosely coupled together. Power is supplied to the primary circuit through a transformer, which charges a capacitor. If the voltage in the capacitor is extremely high, the air resistance between the spark gap drops quickly and now the spark gap becomes a good conductor. The capacitor will discharge through...
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...A Comprehensive Approach for Sub-Synchronous Resonance Screening Analysis Using Frequency scanning Technique Mahmoud Elfayoumy1, Member, IEEE, and Carlos Grande Moran2, Senior Member, IEEE Abstract: The paper presents a comprehensive approach for sub-synchronous resonance (SSR) screening analysis using a developed frequency scanning tool capable of handling power networks with hundreds of buses. PTI’s software packages like PSS/E and IPLAN programs were used for the development of the SSR tool. The frequency scanning technique scans for the sub-synchronous frequency range between 5 Hz to 59 Hz to determine the system driving point impedance (as a function of frequency) viewed from the neutral point of the generating unit under study. The proposed approach was applied to analyze the SSR phenomenon on several steam and gas driven turbine-generator plants in the northern part of the Western System Coordinating Council (WSCC) control area where several 500kV-transmission lines include series capacitor compensation. As a part of the study, credible contingencies that may lead to a network topology susceptible to SSR phenomenon are identified for proposed plants considered in the study. Key Words: Capacitor Compensated Transmission Lines, Sub-synchronous resonance. IEEE Sub-Synchronous Resonance Working Group report [4] presented the basic theory, problem definition, analytical tools, testing, and countermeasures for mitigating the SSR effects. The report also discussed some...
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...frequency. Another objective was to use the RLC circuit to determine the resonant frequency. In order to complete these ojectives the circuit was first set up as in figure 1 and RMS, period, frequency and amplitude were calculated and measured. The experimental amplitude was 0.875Vac, the frequency was 1001Hz, and the period was one second. The difference beween the theoretical frequcy from the signal generator was compared to the experimental frequency giving a 0.1% error. For the second part of the lab the RLC circuit was set up (figure 2) and from there the resonant frequency was found for this was done three times (table 1). After this the voltage drop was measured in the range of 800-300Hz; the different frequencies withc corresponding average power that dissipated in the resistor was inputted into GA (table 2,). From there the power vs frequency graph was plotted. and finally the theoretical angular frequency 1.0846 x 104rad/sec was compared to the experimentally found frequency of 1.0820 x 104rad/sec, giving a 0.24% error. Objective: In experiment number nine “AC Circuits. Oscilloscope” The main objective in the experiment was to use a signal generator to produce an AC signal and determine the relationship between the rms value and the amplitude of the voltage of the wave and also the period and the frequency of the signal. A secondary objective was to use an RLC circuit and determine both the resonant frequency and the dissipated power of the main resistor....
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...VoLUME 56, NUMBER PHYSICAL REVIEW LETTERS 9 3 MAR. cH 1986 Atomic Force Microscope G. Binnig"~ and C. F. Quate' Edward L Gi.nzton Laboratory, Stanford University, ' Stanford, California 94305 and Ch. Gerber" IBM San Jose Research Laboratory, San Jose, California 95193 I, Received 5 December 1985) The scanning tunneling microscope is proposed as a method to measure forces as small as 10 N. As one application for this concept, we introduce a new type of microscope capable of investigating surfaces of insulators on an atomic scale. The atomic force microscope is a combination of the principles of the scanning tunneling microscope and the stylus profilometer. It incorporates a does not damage the surface. Our preliminary results in air demonstrate a lateral resoluprobe that 0 0 tion of 30 A and a vertical resolution less than 1 A. PACS numbers: 68.35.Gy %e are concerned in this paper with the measurement of ultrasmall forces on particles as small as single atoms. %e propose to do this by monitoring the elastic deformation of various types of springs with the scanning tunneling microscope (STM). ' It has been a common practice to use the displacement of springs as a measure of force, and previous methods have relied on electrostatic fields, magnetostatic fields, optical waves, and x rays. Jones~ has reviewed the devices that use variable capacitances and he reports that displacements of 10 4 A can be measured. SQUIDs3...
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