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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Architectural level delay and leakage power modelling of manufacturing process variation

Ni, Chenxi January 2013 (has links)
The effect of manufacturing process variations has become a major issue regarding the estimation of circuit delay and power dissipation, and will gain more importance in the future as device scaling continues in order to satisfy market place demands for circuits with greater performance and functionality per unit area. Statistical modelling and analysis approaches have been widely used to reflect the effects of a variety of variational process parameters on system performance factor which will be described as probability density functions (PDFs). At present most of the investigations into statistical models has been limited to small circuits such as a logic gate. However, the massive size of present day electronic systems precludes the use of design techniques which consider a system to comprise these basic gates, as this level of design is very inefficient and error prone. This thesis proposes a methodology to bring the effects of process variation from transistor level up to architectural level in terms of circuit delay and leakage power dissipation. Using a first order canonical model and statistical analysis approach, a statistical cell library has been built which comprises not only the basic gate cell models, but also more complex functional blocks such as registers, FIFOs, counters, ALUs etc. Furthermore, other sensitive factors to the overall system performance, such as input signal slope, output load capacitance, different signal switching cases and transition types are also taken into account for each cell in the library, which makes it adaptive to an incremental circuit design. The proposed methodology enables an efficient analysis of process variation effects on system performance with significantly reduced computation time compared to the Monte Carlo simulation approach. As a demonstration vehicle for this technique, the delay and leakage power distributions of a 2-stage asynchronous micropipeline circuit has been simulated using this cell library. The experimental results show that the proposed method can predict the delay and leakage power distribution with less than 5% error and at least 50,000 times faster computation time compare to 5000-sample SPICE based Monte Carlo simulation. The methodology presented here for modelling process variability plays a significant role in Design for Manufacturability (DFM) by quantifying the direct impact of process variations on system performance. The advantages of being able to undertake this analysis at a high level of abstraction and thus early in the design cycle are two fold. First, if the predicted effects of process variation render the circuit performance to be outwith specification, design modifications can be readily incorporated to rectify the situation. Second, knowing what the acceptable limits of process variation are to maintain design performance within its specification, informed choices can be made regarding the implementation technology and manufacturer selected to fabricate the design.

Design and optimization of switched-mode circuits for inductive links

Aldhaher, Samer January 2014 (has links)
Wireless power transfer (WPT) via magnetic induction is an emerging technology that is a result of the significant advancements in power electronics. Mobiles phones can now be charged wirelessly by placing them on a charging surface. Electric vehicles can charge their batteries while being parked over a certain charging spot. The possible applications of this technology are vast and the potential it has to revolutionise and change the way that we use today’s application is huge. Wireless power transfer via magnetic induction, also referred to as inductive power transfer (IPT), does not necessarily aim to replace the cable. It is intended to coexist and operate in conjunction with the cable. Although significant progress has been achieved, it is still far from reaching this aim since many obstacles and design challenges still need to be addressed. Low power efficiencies and limited transfer range are the two main issues for IPT. A tradeoff is usually associated with these two issues. Higher efficiencies are only achieved at very short transmission distances, whereas transferring large amounts of power at large distances is possible but at reduced efficiencies. This thesis addressed the limitations and design challenges in IPT systems such as low efficiency and short transmission range, in addition to poor power regulation and coil displacement and misalignment sensitivity. Novel circuit topologies and design solutions have developed for DC/AC inverters and DC/AC rectifiers that will allow for increased performance, higher efficiencies and reduced sensitivity to coil misalignments and displacements. This thesis contributes in four key areas towards IPT. Firstly, a detailed mathematical analysis has been performed on the electric circuit model of inductively coupled coils. This allows for better understanding on how power is distributed amongst the circuit’s elements. Equivalent circuit representations were presented to simplify the design process of IPT systems. Secondly, a review of the different classes and configurations of DC/AC inverters that can be used as primary coil drivers in IPT systems were presented. Class E DC/AC inverters were mathematically analysed in great detail and their performance as primary coil drivers in IPT systems was investigated. Thirdly, novel electronic tuning methods were presented to allow Class E primary coil drivers to operate at optimum switching conditions regardless of the distance between the coils of an IPT system and the value of the load. The saturable reactor was used as the electronic tunable element. Lastly, Class D and Class E AC/DC rectifiers have been used for the first time in IPT systems. Detailed mathematical analysis and extensive experimental results show their superior performance over the conventional half-wave and full-wave AC/DC rectifiers.

Transient and steady state models of alternating current machines

Benaragama, Deepal Sarathsingha January 1977 (has links)
No description available.

The breakdown field strength of compressed sf6 gas

Crichton, B. H. January 1978 (has links)
No description available.

11kV cable protection to permit an increase in distributed generation

Chilvers, Ian Michael January 2005 (has links)
The UK government have set ambitious targets for future energy supply from renewable energy schemes and combined heating and power plants. In order to meet these targets a large amount of distributed generation is expected to be connected to medium voltage distribution networks. The connection of large quantities of distributed generation causes technical problems with existing medium voltage feeder protection schemes. These problems can limit the installed capacity of distributed generation. This work concentrates on the development of an 11kV cable protection scheme in order to minimise or remove the problems with existing cable protection schemes. In the UK, faults on 11kV cable circuits contribute significantly to the total number of customer interruptions. The development of 11kV cable protection can minimise the number of these customer interruptions. This work begins with studies to determine the types of problems encountered with existing 11kV cable protection schemes when distributed generation is connected directly to the 11KV circuit. Based on the results of these studies, the investigation of an 11kV cable protection scheme using distance relays is carried out. In the UK, voltage transformers and communication schemes are seldom installed at 11/0.433 kV distribution substations. The distance relay voltage is measured at the secondary winding of the local 11/0.433 kV distribution transformer, avoiding the cost of installing a voltage transformer at the distribution substation. The performance of the distance scheme is then studied using an electromagnetic transient simulation package. The feasibility and benefits of the new protection scheme are then discussed.

A practical role of smart metering in smart grids development and applications

Lee, Ping Kwong January 2012 (has links)
The thesis explores and presents a practical and potential approach about smart meters in future smart micro grid and power grid applications. Digital electronic meters have been introduced into the markets for quite some time but they are mainly used in power and energy applications. However, they can be further extended and be fully utilized to support the smart power grid and micro grid development. People knew that "smart meters" are typically used for power utilities. However. they can be used as smart interface between power grid and micro grid for multiple sites peak demand response and renewable distributed generation. In this thesis, a practical approach will be introduced from the design to the applications to enhance the energy efficiency of power and micro grids. The smart metering system design architecture from power grid and micro grid will be introduced. Besides, the practical role of smart meters in power quality and energy efficiency application for distributed generation from micro grid will be demonstrated. Future development idea from power quality and energy data mining to expert system will be proposed to enhance the smart grid application as well . Nowadays, many theories are introduced in smart metering system to support smart grid development. In this thesis, the author introduces the smart metering contribution from the practical point of view. It will provide so lid references when engineers try to plan and design their smart micro or power grids. Some of the important points for the system planning and design will be highlighted for future work and consideration. Also, some measurement result from the real applications will be introduced to demonstrate the contributions made to the energy conservation and demand response. Although smart grid is still under discussion, evaluation, development and planning in many countries, the role of smart metering is not clearly defined for recommendation. However, the author implemented few major applications based on the existing infrastructure to conclude that some new areas are proven to be applicable to improve power quality, reliability, demand response and energy efficiency of smart grids.

Novel approaches to hybrid voltage and current sensing for condition monitoring of remotely operated electrical plant

Dziuda, Łukasz January 2007 (has links)
No description available.

Power communications over the last kilometre

Witts, David January 2005 (has links)
No description available.

The development of complex continuous wavelet transform based harmonic analysis and dynamic waveform reconstruction algorithms

Tse Chung Fai, Norman January 2007 (has links)
No description available.

High speed protection of EHV transmission line using wavelet analysis

Solanki, Manishkumar January 2004 (has links)
No description available.

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