949 resultados para Pulse power


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The discussion begins with a discussion of soft power and creativity in contemporary China. The article then examines three development trajectories: territory, technology and taste. The third section examines the effects of taste in more detail through examples of China's creativity in art, philosophy and technology primarily in three key periods, the Western Zhou, Han, and Song The principal argument is that while China’s cultural authority was established on deep Confucian roots, its international influence, and its creativity, is indebted to periods of openness to ideas.

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As various contributors to this volume suggest, the term soft power is multifaceted. In 2002 Joseph Nye, the political scientist who coined the term more than a decade previously, noted that the soft power of a country rests on three resources: a country’s culture, its political values, and its foreign policies (Nye 2002). However, several factors can be drawn together to explain China’s adoption of this concept. First, China’s economic influence has precipitated a groundswell of nationalism, which reached its apex at the Opening Ceremony of the 2008 Beijing Olympics. This global media event provided an international platform to demonstrate China’s new found self-confidence. Second, cultural diplomacy and foreign aid, particularly through Third World channels is seen by the Chinese Communist Party leadership as an appropriate way to extend Chinese influence globally (Kurlantzick 2007). Third, education in Chinese culture through globally dispersed Confucius Institutes is charged with improving international understanding of Chinese culture and values, and in the process renovating negative images of China. Fourth, the influence of Japanese and Korean popular culture on China’s youth cultures in recent years has caused acute discomfit to cultural nationalists. Many contend it is time to stem the tide. Fifth, the past few years have witnessed a series of lively debates about the importance of industries such as design, advertising, animation and fashion, resulting in the construction of hundreds of creative clusters, animation centres, film backlots, cultural precincts, design centres and artist lofts.

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Over the past century numerous waves of transnational media have washed across East Asia with cycles emanating from various centers of cultural production, such as Tokyo, Hong Kong, and Seoul. Most recently the People’s Republic of China (PRC) has begun to exert growing influence over the production and flow of screen media, a phenomenon tied to the increasing size and power of its overall economy. The country’s rising status achieved truly global recognition during the 2008 Beijing Olympics. In the seven years leading up to the event, the Chinese economy tripled in size, expanding from $1.3 trillion to almost $4 trillion, a figure that made it the world’s third largest economy, slightly behind Japan, but decisively ahead of its European counterparts, Germany, France, and the United Kingdom. The scale and speed of this transformation are stunning. Just as momentous are the changes in its film, television, and digital media markets, which now figure prominently in the calculations of producers throughout East Asia.

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Common mode voltage generated by a power converter in combination with parasitic capacitive couplings is a potential source of shaft voltage in an AC motor drive system. In this paper, a three-phase motor drive system supplied with a single-phase AC-DC diode rectifier is investigated in order to reduce shaft voltage in a three-phase AC motor drive system. In this topology, the common mode voltage generated by the inverter is influenced by the AC-DC diode rectifier because the placement of the neutral point is changing in different rectifier circuit states. A pulse width modulation technique is presented by a proper placement of the zero vectors to reduce the common mode voltage level, which leads to a cost effective shaft voltage reduction technique without load current distortion, while keeping the switching frequency constant. Analysis and simulations have been presented to investigate the proposed method.

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The flying capacitor multicell inverter (FCMI) possesses natural balancing property. With the phase-shifted (PS) carrier-based scheme, natural balancing can be achieved in a straightforward manner. However, to achieve natural balancing with the harmonically optimal phase-disposition (PD) carrierbased scheme, the conventional approaches require (n-1) x (n-1) trapezoidal carrier signals for an n-level inverter, which is (n-1) x (n-2) times more than that in the standard PD scheme. This paper proposes two improved natural balancing strategies for FMI under PD scheme, which use the same (n-1) carrier signals as used in the standard PD scheme. In the first scheme, on-line detection is performed of the band in which the modulation signal is located, corresponding period number of the carrier, and rising or falling half cycle of the carrier waveform to generate the switching signals based on certain rules. In the second strategy, the output voltage level selection is first processed and the switching signals are then generated according to a rule based on preferential cell selection algorithm. These methods are easy to use and can be simply implemented as compared to the other available methods. Simulation and experimental results are presented for a five-level inverter to verify these proposed schemes.

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Three different methods of inclusion of current measurements by phasor measurement units (PMUs) in a power sysetm state estimator is investigated. A comprehensive formulation of the hybrid state estimator incorporating conventional, as well as PMU measurements, is presented for each of the three methods. The behaviour of the elements because of the current measurements in the measurement Jacobian matrix is examined for any possible ill-conditioning of the state estimator gain matrix. The performance of the state estimators are compared in terms of the convergence properties and the varian in the estimated states. The IEEE 14-bus and IEEE 300-bus systems are used as test beds for the study.

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In this paper a new approach is proposed for interpreting of regional frequencies in multi machine power systems. The method uses generator aggregation and system reduction based on coherent generators in each area. The reduced system structure is able to be identified and a kalman estimator is designed for the reduced system to estimate the inter-area modes using the synchronized phasor measurement data. The proposed method is tested on a six machine, three area test system and the obtained results show the estimation of inter-area oscillations in the system with a high accuracy.

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The antecedents of channel power (e.g. El-Ansary and Stern, 1972) and the impact of channel structure ( e.g. Anderson and Narus,1984) on channel dynamics have long been important topics within the channel literature. In addition to the theoretical and methodological contributions, research in these areas has helped channel managers to understand how power is generated and used in coordinating distribution strategies in different contexts. The study presented in this paper builds upon these previous literatures, which are first briefly reviewed below.

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This paper presents a novel topology for the generation of high voltage pulses that uses both slow and fast solid-state power switches. This topology includes diode-capacitor units in parallel with commutation circuits connected to a positive buck-boost converter. This enables the generation of a range of high output voltages with a given number of capacitors. The advantages of this topology are the use of slow switches and a reduced number of diodes in comparison with conventional Marx generator. Simulations performed for single and repetitive pulse generation and experimental tests of a prototype hardware verify the proposed topology.

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The application of variable structure control (VSC) for power systems stabilization is studied in this paper. It is the application, aspects and constraints of VSC which are of particular interest. A variable structure control methodology has been proposed for power systems stabilization. The method is implemented using thyristor controlled series compensators. A three machine power system is stabilized using a switching line control for large disturbances which becomes a sliding control as the disturbance becomes smaller. The results demonstrate the effectiveness of the methodology proposed as an useful tool to suppress the oscillations in power systems.

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Multilevel converters are used in high power and high voltage applications due to their attractive benefits in generating high quality output voltage. Increasing the number of voltage levels can lead to a reduction in lower order harmonics. Various modulation and control techniques are introduced for multilevel converters like Space Vector Modulation (SVM), Sinusoidal Pulse Width Modulation (SPWM) and Harmonic Elimination (HE) methods. Multilevel converters may have a DC link with equal or unequal DC voltages. In this paper a new modulation technique based on harmonic elimination method is proposed for those multilevel converters that have unequal DC link voltages. This new technique has better effect on output voltage quality and less Total Harmonic Distortion (THD) than other modulation techniques. In order to verify the proposed modulation technique, MATLAB simulations are carried out for a single-phase diode-clamped inverter.

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This paper analyses the ways in which it is possible to imagine the relationship between sexual penetration and the expression of power. Taking the particular instance of a penetrative act in the US gay porn film Hard at Work, it applies a series of critical approaches in an attempt to make sense of perceived power relations in that text. Equations of power and activity, power and physical strength, power and the possession of a penis, power and the ability to gaze and power and the control of discourse are all considered and found to be inadequate to the task. The paper finally suggests that in order to usefully discuss relations of power in sexual acts, it is necessary to accept the radical reconceptualisation of power suggested by Mark Gibson, and begin to understand it not as an objective, measurable and real quantity, but as an effect of the interpretation of particular situations.

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In Australia, the extent of a mortgagee’s duty when exercising power of sale has long been the subject of conjecture. With the advent of the global financial crisis in the latter part of 2008, there has been some concern to ensure that the interests of mortgagors are adequately protected. In Queensland, concern of this type resulted in the enactment of the Property Law (Mortgagor Protection) Amendment Act 2008 (Qld). This amending legislation operates to both extend and strengthen the operation of s 85 of the Property Law Act 1974 (Qld) which regulates the mortgagee’s power of sale in Queensland. This article examines the impact of this amending legislation which was hastily introduced and passed by the Queensland Parliament without consultation and which introduces a level of prescription in relation to a sale under a prescribed mortgage which is without precedent elsewhere in Australia.

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The purpose of this paper is to frame effective models of arts management for Australia in the nineties and beyond based on an analysis of historical practices. The evolutionary process of government subvention of the arts through non-profit arts organisations provides a clear statement of the role of power and influence. In particular the ascendancy of arts organisations and their management constitute a background against which to study other non-profit corporations.

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In 2007 I introduced short-format educational podcast resources that reinforced conceptual teaching and learning in an interdisciplinary tertiary science study area (biochemistry). This study aims to determine student attitudes to the perceived usefulness and benefit of short-format educational podcasts, and presents the findings (qualitative and quantitative) from surveys obtained from three offerings of the science teaching unit (2007, 2008 and 2009). Podcasts were recorded (MP3 audio files) separately from the instructive lecture sessions, and subsequent to the weekly lecture, short-format podcasts summarising the key learning objectives were integrated within the resources presented through the students learning management system (Blackboard). The vast majority (>88%) of students utilised the podcast resources, indicating a high level of acceptance and uptake for this portable educational technology. The respondents reported that podcasts focused their attention to core learning concepts and supported their understanding and learning of the lecture material. Furthermore, the data showed that respondents agreed strongly that podcasts assisted with study and revision for examinations and, somewhat surprisingly, there was a perception that podcasts positively impacted on examination performance. Overall, student users perceived that podcasting is as an effective and valuable educational tool that offers convenience and flexibility for their learning and understanding of a tertiary science study area, such as biochemistry.