title: An analysis of pulse transformers

authors: Harrison, Craig Brendon

abstract: This thesis focuses on developing a comprehensive understanding of the behaviour of the output pulse transformer used in an electric fence energiser, a unique application which has received little attention in the literature.

Maxwell’s Equations form the starting point for an investigation into the magnetisation of the magnetic core under high current pulse conditions. An equation is derived which describes the time dependent nature of the penetration of the magnetic field into the core material. The concept of a region of high permeability moving into the lamination as a result of rapid saturation is also developed.

Quantitative results are obtained for the area of this high permeability region, both from the pulse magnetisation equation and by analytical methods. The analytical approach is also used to derive expressions for the pulse current, output voltage and power, and inductance. The analytical model of the output transformer provides much insight into the transformer’s behaviour, and into the influence upon performance of the various circuit elements.

The description of pulse magnetisation is a key factor in the development of both analytical and electrical circuit models of the output transformer.

The final part of the thesis considers the output transformer from the perspective of an electrical circuit model, which is developed as a direct representation of the physical transformer. The inductor-reluctance method is used to develop the model, and methods of calculating each parameter are derived, so that the final model may be obtained directly from the transformer’s specification without the need for experimental measurements. The electrical circuit model is implemented using a SPICE simulator, and an analysis of the transformer highlights the major design parameters.

The description of pulse magnetisation, the analytical model and the electrical circuit model combine to provide a comprehensive description of the behaviour of the output transformer, and provide the tools required for design and further investigation of this application.

text: An analysis of pulse transformers This thesis focuses on developing a comprehensive understanding of the behaviour of the output pulse transformer used in an electric fence energiser, a unique application which has received little attention in the literature.

Maxwell’s Equations form the starting point for an investigation into the magnetisation of the magnetic core under high current pulse conditions. An equation is derived which describes the time dependent nature of the penetration of the magnetic field into the core material. The concept of a region of high permeability moving into the lamination as a result of rapid saturation is also developed.

Quantitative results are obtained for the area of this high permeability region, both from the pulse magnetisation equation and by analytical methods. The analytical approach is also used to derive expressions for the pulse current, output voltage and power, and inductance. The analytical model of the output transformer provides much insight into the transformer’s behaviour, and into the influence upon performance of the various circuit elements.

The description of pulse magnetisation is a key factor in the development of both analytical and electrical circuit models of the output transformer.

The final part of the thesis considers the output transformer from the perspective of an electrical circuit model, which is developed as a direct representation of the physical transformer. The inductor-reluctance method is used to develop the model, and methods of calculating each parameter are derived, so that the final model may be obtained directly from the transformer’s specification without the need for experimental measurements. The electrical circuit model is implemented using a SPICE simulator, and an analysis of the transformer highlights the major design parameters.

The description of pulse magnetisation, the analytical model and the electrical circuit model combine to provide a comprehensive description of the behaviour of the output transformer, and provide the tools required for design and further investigation of this application.

year: 1998

title: Design and evaluation of an optimistic CPU: the warp engine

authors: Littin, Richard H.

abstract: Instruction pipelining, out-of-order execution, and branch prediction are techniques that improve performance in processors by manipulating the flow of instructions. These control flow manipulations alone are not adequate to allow large numbers of instructions to execute in parallel because performance is limited by accesses to the relatively slow memory system. Performance can be improved by speculating on the outcomes of control decisions, and the values of data in memory, returning results early. This thesis investigates the requirements of an architecture that speculates on control flow decisions and data values to improve performance through instruction level parallelism.

A new architecture, the WarpEngine, that speculates on control flow decisions and data values is presented. This architecture is shown to have the potential to extract performance through parallelism an order of magnitude larger than that obtained by contemporary microprocessors. Control speculation is achieved using a novel tree-based mechanism that produces multiple flows of control. This scalable mechanism is shown to generate a large group of instructions that can execute in parallel. Also, it is essential that memory accesses are allowed to occur out of programmed order. This form of data speculation is shown to break false data dependencies, improving performance. The use of state saving resources is examined and the limitations of in-order retirement schemes are shown. These results indicate that the management of these resources is critical to obtaining good performance.

Virtual ordered simulation is introduced as a new simulation methodology for modelling out-of-order and speculative architectures. This novel simulation technique is unique because each instruction is only inspected and processed once, and unlike other simulation methodologies unlimited resources can be modelled. Individual components can be constrained in isolation so that their effect on performance can be examined in detail. Investigations performed assuming unbounded resources provide new insight into the limits imposed by individual processor components.

The architecture presented shows potential for performance well beyond that of contemporary and research architectures. The insights into the limitations of processor components apply to many computer architectures.

text: Design and evaluation of an optimistic CPU: the warp engine Instruction pipelining, out-of-order execution, and branch prediction are techniques that improve performance in processors by manipulating the flow of instructions. These control flow manipulations alone are not adequate to allow large numbers of instructions to execute in parallel because performance is limited by accesses to the relatively slow memory system. Performance can be improved by speculating on the outcomes of control decisions, and the values of data in memory, returning results early. This thesis investigates the requirements of an architecture that speculates on control flow decisions and data values to improve performance through instruction level parallelism.

A new architecture, the WarpEngine, that speculates on control flow decisions and data values is presented. This architecture is shown to have the potential to extract performance through parallelism an order of magnitude larger than that obtained by contemporary microprocessors. Control speculation is achieved using a novel tree-based mechanism that produces multiple flows of control. This scalable mechanism is shown to generate a large group of instructions that can execute in parallel. Also, it is essential that memory accesses are allowed to occur out of programmed order. This form of data speculation is shown to break false data dependencies, improving performance. The use of state saving resources is examined and the limitations of in-order retirement schemes are shown. These results indicate that the management of these resources is critical to obtaining good performance.

Virtual ordered simulation is introduced as a new simulation methodology for modelling out-of-order and speculative architectures. This novel simulation technique is unique because each instruction is only inspected and processed once, and unlike other simulation methodologies unlimited resources can be modelled. Individual components can be constrained in isolation so that their effect on performance can be examined in detail. Investigations performed assuming unbounded resources provide new insight into the limits imposed by individual processor components.

The architecture presented shows potential for performance well beyond that of contemporary and research architectures. The insights into the limitations of processor components apply to many computer architectures.

year: 2000

title: William Grey Nicholls and Rihitoto Mataia

authors: Hart, Philip

abstract: The son of a Pakeha Maori, Nicholls had an illustrious ancestry on his mother’s side, and his wife Rihitoto Mataia also had a distinguished whakapapa. From the 1870s Nicholls farmed in Ohinemuri, and as a licensed interpreter played an important role in land transactions at the same time as he was becoming prominent in the Pakeha community. For over 30 years he invested in mining, starting at Te Aroha in 1880. He also invested in a variety of other enterprises, becoming prosperous through these investments, his farming, and in particular by acquiring and selling land. Over a 40-year period, Nicholls conducted many cases in the land court, and assisted Pakeha to acquire Maori land, and also acquired a considerable amount of land for himself and Rihitoto, who inherited many blocks from her father (but had to pay off his massive debts).
         Whereas Rihitoto was a prominent leader in the Maori community of Hauraki, Nicholls had the same role in Pakeha society. Active in a variety of initiatives to benefit the Ohinemuri community, he was a popular member and chairman of the Ohinemuri County Council, and late in life was elevated to the Legislative Council. Reputedly he assisted Maori in various ways, but clearly he identified rather more with his Pakeha ancestry. His career was a remarkably successful one, and his wife was also successful in maximizing the benefits that could be derived from her ancestry.

text: William Grey Nicholls and Rihitoto Mataia The son of a Pakeha Maori, Nicholls had an illustrious ancestry on his mother’s side, and his wife Rihitoto Mataia also had a distinguished whakapapa. From the 1870s Nicholls farmed in Ohinemuri, and as a licensed interpreter played an important role in land transactions at the same time as he was becoming prominent in the Pakeha community. For over 30 years he invested in mining, starting at Te Aroha in 1880. He also invested in a variety of other enterprises, becoming prosperous through these investments, his farming, and in particular by acquiring and selling land. Over a 40-year period, Nicholls conducted many cases in the land court, and assisted Pakeha to acquire Maori land, and also acquired a considerable amount of land for himself and Rihitoto, who inherited many blocks from her father (but had to pay off his massive debts).
         Whereas Rihitoto was a prominent leader in the Maori community of Hauraki, Nicholls had the same role in Pakeha society. Active in a variety of initiatives to benefit the Ohinemuri community, he was a popular member and chairman of the Ohinemuri County Council, and late in life was elevated to the Legislative Council. Reputedly he assisted Maori in various ways, but clearly he identified rather more with his Pakeha ancestry. His career was a remarkably successful one, and his wife was also successful in maximizing the benefits that could be derived from her ancestry.

year: 2016