236,408 research outputs found

    Less-conventional low-consumption galvanic separated MOSFET-IGBT gate drive supply

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    A simple half-bridge, galvanic separated power supply which can be short circuit proof is proposed for gate driver local supplies. The supply is made while hacking a common mode type filter as a transformer, as the transformer shows a good insulation, it has a very low parasitic capacitance between primary and secondary coils, and it is cost-effective. Very low standby losses were observed during lab experiments. This makes it compatible with energy efficient drives and solar inverters

    Programmable photonics : an opportunity for an accessible large-volume PIC ecosystem

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    We look at the opportunities presented by the new concepts of generic programmable photonic integrated circuits (PIC) to deploy photonics on a larger scale. Programmable PICs consist of waveguide meshes of tunable couplers and phase shifters that can be reconfigured in software to define diverse functions and arbitrary connectivity between the input and output ports. Off-the-shelf programmable PICs can dramatically shorten the development time and deployment costs of new photonic products, as they bypass the design-fabrication cycle of a custom PIC. These chips, which actually consist of an entire technology stack of photonics, electronics packaging and software, can potentially be manufactured cheaper and in larger volumes than application-specific PICs. We look into the technology requirements of these generic programmable PICs and discuss the economy of scale. Finally, we make a qualitative analysis of the possible application spaces where generic programmable PICs can play an enabling role, especially to companies who do not have an in-depth background in PIC technology

    Modelling for optimisation of self-powered wireless sensor nodes

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    Characterization of Acoustic Resonance in a High Pressure Sodium Lamp

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    With the last decades, the high pressure sodium (HPS) lamp has been supplied in high frequency in order to increase the efficacy of the lamp/ballast system. However, at some given frequencies, standing acoustic waves, namely acoustic resonance (AR), might develop in the burner and cause lamp luminous fluctuation, extinction and destruction in the most serious case. As we seek for a control method to detect and avoid the lamp AR some main characteristics of the acoustic resonances in a 150W HPS lamp are presented in this paper,. The first one is the characteristic of the lamp AR threshold power, the second one is the differences between forward and backward frequency scanning effects during lamp open loop operation. Thirdly, lamp AR behaviour in closed loop operation with an LCC half bridge inverter will be presented and leads to a new point of view and a change in the choice of the AR detection method. These characteristics allow us to further understand the AR and to better control the lamp

    A Novel Reduced Components Model Predictive Controlled Multilevel Inverter for Grid-Tied Applications

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    This paper presents an improved single-phase Multilevel Inverter (MLI) which is conceptualized to reduce power switches along with separate DC voltage sources. Compared with recent modular topologies, the proposed MLI employs a reduced number of components. The proposed inverter consists of a combination of two circuits, i.e., the level generation and polarity generation parts. The level generation part is used to synthesize different output voltage levels, while the polarity inversion is performed by a~conventional H-bridge circuit. The performance of the proposed topology has been studied using s single-phase seven-level inverter, which utilizes seven power switches and three independent DC voltage sources. Model Predictive Control (MPC) is applied to inject a sinusoidal current into the utility grid which exhibits low Total Harmonic Distortion (THD). Tests, including a~change in grid current amplitude as well as operation under variation in Power Factor (PF), have been performed to validate the good performance obtained using MPC. The effectiveness of the proposed seven-level inverter has been verified theoretically using MATLAB Simulink. In addition, Real-Time (RT) validation using the dSPACE-CP1103 has been performed to confirm the system performance and system operation using digital platforms. Simulation and RT results show improved THD at 1.23% of injected current

    The case of Foxconn in Turkey: benefiting from free labour and anti-union policy

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    Starting from the 2000s Foxconn invested in Czechia, Slovakia, Hungary, Russia and Turkey, implementing a territorial diversification strategy aimed at getting nearer to its end markets. This chapter investigates the development of Foxconn in Turkey where the multinational owns a plant with about 400 workers. A few kilometres from the city of \uc7orlu and close to highways, ports and international airports, the plant enables Foxconn to implement an efficient global supply chain. We illustrate this process by examining the company\u2019s localisation within a special economic zone, underlining the economic advantages derived from such a tax regime, bringing labour costs down to the Chinese level and obtaining proximity to European, North African and Middle East customers, thus lowering logistic costs. We also analyse the roles of labour flexibility and trade unions. In order to impose far-reaching flexibility on its workers Foxconn put in place a range of strategies, including an hours bank system, multitask operators and the recruitment of apprentices thanks a special programme funded by the state. We show how these have been crucial for Foxconn\u2019s just-in-time production contrasting its labour turnover problem. Finally, we highlight how the company has been able to implement a flexible working pattern, weaken the trade unions and undercut workers\u2019 opposition, thanks to favourable labour laws approved by successive governments in the past thirty years

    Introduction

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    This book investigates restructuring in the electronics industry and in particular the impact of a \u2018Chinese\u2019 labour regime on work and employ - ment practices in electronics assembly in Europe.1 Electronics is an extremely dynamic sector, characterized by an ever-changing organi - zational structure, as well as cut-throat competition, particularly in manufacturing. Located primarily in East Asia, electronics assembly has become notorious for poor working conditions, low unionisation and authoritarian labour relations. However, hostile labour relations and topdown HR policies are not unique to East Asia. They have become associated with the way the sector is governed more broadly, with a number of Western companies also coming to rely on such practices

    Low Power Processor Architectures and Contemporary Techniques for Power Optimization – A Review

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    The technological evolution has increased the number of transistors for a given die area significantly and increased the switching speed from few MHz to GHz range. Such inversely proportional decline in size and boost in performance consequently demands shrinking of supply voltage and effective power dissipation in chips with millions of transistors. This has triggered substantial amount of research in power reduction techniques into almost every aspect of the chip and particularly the processor cores contained in the chip. This paper presents an overview of techniques for achieving the power efficiency mainly at the processor core level but also visits related domains such as buses and memories. There are various processor parameters and features such as supply voltage, clock frequency, cache and pipelining which can be optimized to reduce the power consumption of the processor. This paper discusses various ways in which these parameters can be optimized. Also, emerging power efficient processor architectures are overviewed and research activities are discussed which should help reader identify how these factors in a processor contribute to power consumption. Some of these concepts have been already established whereas others are still active research areas. © 2009 ACADEMY PUBLISHER

    Flexible workforces and low profit margins: electronics assembly between Europe and China

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    This book investigates restructuring in the electronics industry and in particular the impact of a \u2018Chinese\u2019 labour regime on work and employ - ment practices in electronics assembly in Europe.1 Electronics is an extremely dynamic sector, characterized by an ever-changing organi - zational structure, as well as cut-throat competition, particularly in manufacturing. Located primarily in East Asia, electronics assembly has become notorious for poor working conditions, low unionisation and authoritarian labour relations. However, hostile labour relations and topdown HR policies are not unique to East Asia. They have become associated with the way the sector is governed more broadly, with a number of Western companies also coming to rely on such practices
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