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1
McGillan, Glen. "The design of an electric fence fault-finder : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering in Computer Systems Engineering at Massey University, Albany, New Zealand." Massey University, 2009. http://hdl.handle.net/10179/1161.
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Electrified fencing is commonly used throughout the world to control animals with smaller and cheaper fence constructions than would otherwise be necessary with non-electrified wires. Typical installations have a long wire or wires starting from an electric fence energiser and then surrounding fields in various complex configurations. Faults on electric fences can be difficult to locate, with the average fence using tens of kilometres of wire. Basic fault-finding tools allow an operator to read the peak fence voltage, requiring the user to decide whether a fault is present and to randomly search for the source of the problem. The focus of this thesis is to develop a device that reduces the time to locate faults on a fence by providing more information about the location and nature of a fault, and will point in the direction of the fault.
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Sowden, Bradley Claude. "The performance of DS-CDMA cellular systems with variable-bit-rate traffic." Thesis, University of Auckland, 2009. http://hdl.handle.net/2292/5211.
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The deployment of third generation (3G) cellular systems is resulting in a transition from cellular systems that predominantly carry constant-bit-rate (CBR) voice traffic to multi-service packet based systems that predominantly carry variable-bit-rate (VBR) traffic. With 3G DS-CDMA cellular systems there is a direct relationship between user traffic and propagation dependent performance as additional traffic causes increased system interference. This thesis investigates the impact of VBR traffic on the propagation dependent performance of DS-CDMA cellular systems that utilise frame-by-frame dynamic resource allocation on the radio channel. A DS-CDMA cellular system model is developed and the downlink performance of both outdoor macro-cellular and indoor pico-cellular systems is evaluated with a variety of traffic types. Both traffic scheduling performance and propagation dependent performance are evaluated as the two are inter-linked. Scenarios are identified where propagation dependent performance is sensitive to the statistical properties of the user traffic streams and it is shown that a significant performance difference potentially exists between different traffic types when the number of users per cell is low. When a significant performance difference does exist, burstier more variable traffic generally results in superior propagation dependent performance. The base transceiver station (BTS) transmitter power mean and variance provides a good indication of the level of propagation dependent performance regardless of the specific traffic type. Traffic scheduling policies that deliberately reduce the variability of user traffic streams are considered and in terms of propagation dependent performance these are shown to have a minimal impact on the performance difference between different traffic types. The implications of VBR traffic on DS-CDMA cellular system design are outlined and it is shown that VBR traffic can be approximated as CBR traffic in many scenarios and this is a convenient approximation as it simplifies system design and detailed traffic models do not need to be developed.
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Zhang, Heng. "Otahuhu B Power Station condenser in-leakage analysis and condensate monitoring system : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Electronics Engineering at Massey University, Wellington, New Zealand." Massey University, 2008. http://hdl.handle.net/10179/950.
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Considerable ongoing risk of condenser in-leakage exists at Otahuhu B (OTB) Power Station. The condenser cooling water used at OTB station is corrosive brackish water with exceedingly high sodium and chloride concentrations. Significant signs of corrosion inside the condenser have been found recently. In the event of condenser in-leakage, the salt contaminants in the cooling water will directly enter the Heat Recovery Steam Generator (HRSG) with the potential for significant and costly damage resulting in a long plant outage. A dynamic mathematical model was developed in the thesis to analyse the consequences of condenser in-leakage at OTB station. The analysis results show that the tolerance of the condenser to any leakage of cooling water is almost zero. Because the existing condensate monitoring system is not designed to detect contamination in this time frame, a new fast response system is required to detect condenser in-leakage immediately. A new dedicated fast response condensate monitoring system has been engineered and installed at OTB station as a part of the project scope. The new system dramatically reduces the response time to condenser in-leakage events. Critical instruments utilise multiple redundancy schemes to enhance the availability and reliability of the system. In addition, action level voting, timing, and alarming has been automated to assist operators in making correct decisions. The new condensate monitoring system is presently fully functional. The project has successfully achieved the objective of controlling the risk of condenser in-leakage events and minimising damage and negative effects on the plant.
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Wang, Kevin I.-Kai. "Multi-agent based ambient intelligence platform." Thesis, University of Auckland, 2009. http://hdl.handle.net/2292/5212.
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The vision of Ambient Intelligence (AmI) can be realised through the integration of embedded technologies, distributed systems, middleware and human machine interfaces and many research efforts have been made to advance these technologies. However, the exclusiveness of these ambient intelligence technologies has reduced their practical values. In this thesis, a novel AmI platform is proposed to facilitate the integration and interoperability of various technologies in the process of developing AmI applications. The platform defines the overall software/hardware architecture and communication interfaces and provides a common base for development, operation and future adaptation of AmI applications. The proposed platform consists of four layers, the physical ubiquitous environment, middleware, multi-agent system (MAS) and application layer. The ubiquitous environment layer accommodates any type of embedded device network for interconnecting different sensors, actuators and computing devices. The middleware layer is built using an IP-based service discovery protocol, Universal Plug and Play (UPnP), which provides a unique communication interface for controlling and monitoring embedded devices. The MAS handles the core distributed and adaptive control functionality and communication with user interfaces. The application layer contains any type of user interface for different AmI applications. An XML-based content language is designed with an XML schema and seven XML messages. The content language standardises the way of interpreting contents of communication between different user interfaces and the MAS. Based on the proposed platform, a complete AmI application prototype called Distributed Embedded Intelligence Room (DEIR) has been implemented. Four different device networks, the SmartHouse network, IP network, Bluetooth and Zigbee network, have been integrated in DEIR to interconnect various embedded sensors and devices. The MAS is implemented using Java Agent DEvelopment framework (JADE). Four application specific agents, known as the UPnP control point agent, IP interface agent, fuzzy inference agent and decision tree agent, are designed and implemented. The UPnP control point agent provides MAS the ability to monitor and to control the underlying hardware devices through the UPnP middleware layer. The IP interface agent handles communication with user interfaces over socket connections. Fuzzy inference and decision tree agents are implemented to provide personalised learning and automated control capabilities. Three user interfaces, including a remote graphical user interface, a mobile PDA interface and a 3D virtual reality interface are implemented. Contents of communication between these user interfaces and the MAS are encoded using the proposed XML content language and transmitted over socket connections. The AmI application prototype, DEIR, has demonstrated the ability of integrating multiple device networks and multiple user interfaces, which is a vital feature for most AmI applications. Two case studies have been carried out to incorporate two adaptive learning and controlling algorithms, known as the adaptive online fuzzy inference system (AOFIS) and ID3 decision tree algorithm, in the MAS of DEIR. The results of case studies show that DEIR has the ability of incorporating multiple adaptive control algorithms as multiple agents. In addition, comparable or better offline learning accuracy and learning speed have been achieved by DEIR compared with other advanced adaptive control algorithms.Whole document restricted, but available by request, use the feedback form to request access.
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Sen, Gupta Gourab. "Autonomous agents in a dynamic collaborative environment : a thesis presented in partial fulfilment of the requirements for the degree of PhD in Engineering at Massey University, Palmerston North, New Zealand." Massey University, 2008. http://hdl.handle.net/10179/811.
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The proliferation of robots in industry and every day human life is gaining momentum. After the initial few decades of employment of robots in the industry, especially the automotive assembly plants, robots are now entering the home and offices. From being pick-and-place manipulators, robots are slowly being transformed in shape and form to be more anthropomorphic. The wheeled robots are however here to stay for the foreseeable future until such time as artificial muscles, and efficient means to control them, are well developed. The next phase of development of robots will be for the service industry. Robots will cooperate with each other to accomplish collaborative tasks to aid human life. They will also collaborate with human beings to assist them in doing tasks such as lifting loads and moving objects. At the same time, with the advancement of hardware, robots are becoming very fast and are capable of being programmed with more intelligence. Coupled with this is the availability of sophisticated sensors with which the robots can perceive the real world around them. Combinations of these factors have created many challenging areas of research. Several factors affect the performance of robots in a dynamic collaborative environment. The research presented in this thesis has identified the major contributing factors, namely fast vision processing, behaviour programming, predictive movement and interception control, and precise motion control, that collectively have influence on the performance of robots which are engaged in a collaborative effort to accomplish a task. Several novel techniques have been proposed in this thesis to enhance the collective performance of collaborating robots. In many systems, vision is used as one of the sensory inputs for the robot’s perception of the environment. This thesis describes a new colour space and the use of discrete look-up-tables (LUT) for very fast and robust colour segmentation and real-time identification of objects in the robot’s work space. A distributed camera system and a stereo vision using a single camera are reported. Advanced filtering has been applied to the vision data for predictive identification of the position and orientation of moving robots and targets, and for anticipatory interception control. Collaborative tasks are generally complex and robots need to be capable of exhibiting sophisticated behaviours. This thesis has detailed the use of State Transition Based Control (STBC) methodology to build a hierarchy of complex behaviour. Behaviour of robots in a robot soccer game and features such as role selection and obstacle avoidance have been built using STBC. A novel methodology for advanced control of fast robots is detailed. The algorithm uses a combination of Triangular Targeting Algorithm (TTA) and Proximity Positioning Algorithm (PPA) to position a robot behind an object aligned with a target. Various forms of velocity profiling have been proposed and validated with substantial test results. The thesis ends by looking at future scenarios where robots and human beings will coexist and work together to do many collaborative tasks. Anthropomorphic robots will be more prevalent in future and teleoperation will gain momentum. Throughout the thesis, the engineering applicability of proposed algorithms and architectures have been emphasised by testing on real robots.
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Noble, Frazer K. "Wireless vehicle presence detection using self-harvested energy : a thesis in partial fulfilment of the requirements for the degree of Master of Engineering in Mechatronics, Massey University, Albany, New Zealand." Massey University, 2009. http://hdl.handle.net/10179/1078.
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Rising from the “excess demand” modern societies and economies place on limited road resources, congestion causes increased vehicle emissions, decreases national efficiency, and wastes time (Downs, 2004). In order to minimise congestion’s impacts, traffic management systems gather traffic data and use it to implement efficient management algorithms (Downs, 2004). This dissertation’s purpose has been the development of a distributable vehicle presence detection sensor, which will wirelessly provide vehicle presence information in real time. To address the sensor’s wireless power requirements, the feasibility of self-powering the device via harvested energy has been investigated. Piezoelectric, electrostatic, and electromagnetic energy harvesting devices’ principles of operation and underlying theory has been investigated in detail and an overview presented alongside a literature review of previous vibration energy harvesting research. An electromagnetic energy harvesting device was designed, which consists of: a nylon reinforced rubber bladder, hydraulic piston, neodymium magnets, and wire-wound coil housing. Preliminary testing demonstrated a harvested energy between 100mJ and 205mJ per axle. This amount is able to be transferred to a 100O load when driven over at speeds between 10km/h and 50km/h. Combined with an embedded circuit, the energy harvester facilitated the development of a passive sensor, which is able to wirelessly transmit a vehicle’s presence signal to a host computer. The vehicle detected event is displayed via a graphical user interface. Energy harvesting’s ability to power the embedded circuit’s wireless transmission, demonstrated the feasibility of developing systems capable of harvesting energy from their environment and using it to power discrete electronic components. The ability to wirelessly transmit a vehicle’s presence facilitates the development of distributable traffic monitoring systems, allowing for remote traffic monitoring and management.
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Thrimawithana, Duleepa J. "A novel electric fence energizer : design and analysis." Thesis, University of Auckland, 2008. http://hdl.handle.net/2292/4264.
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Continual advancements in technology have led to the development of reliable, efficient and economical farm management systems, many of which utilize electric fences for effective control of farm animals. An electric fence system constitutes a conducting fence structure that is energized by a high voltage signal generated from an electric fence energizer. Modern electric fence energizers employ a pulsed power supply together with an appropriate high voltage charging scheme to generate high voltage pulses that energize the fence structure. The high voltage pulse delivers a non-lethal electric shock to an animal that comes into contact with the fence, and the consequent psychological impact on the animal is such that it is less likely to come into contact with the fence again. The complexity associated with modelling electric fence systems has hindered the development of proper mathematical tools that aid their design and optimization, and as a consequence, electric fence systems are currently designed using empirical rules together with a trial and error design approach. This Thesis therefore aims to fulfil this need by presenting new technologies and mathematical tools that can be used to design both intelligent and optimized electric fence systems. It presents a comprehensive study on electric fencing systems, which includes a detailed mathematical analysis on pulse propagation properties of electric fence networks and the development of high performance fence energizers that incorporates new pulses power supply technologies and high voltage charging schemes. With regard to the pulsed power technologies, two novel topologies with the ability to adapt their output pulse shape according to the fence conditions are proposed. The performance of these technologies is analyzed mathematically, and verified experimentally. In comparison to the existing fence energizer technology, energizers that are based on the proposed pulsed power supply designs are superior in performance. Furthermore, a novel Buck-Boost pushpull parallel-resonant converter technique, which is suitable for charging high voltage storage capacitors in an energizer, is also presented. The proposed technique allows for the push-pull parallel-resonant converter to operate with a frequency dependent variable voltage gain over a wide load range while maintaining zero voltage switching (ZVS). The operation of the converter is analyzed mathematically and verified experimentally to validate the proposed technique. In order to gain an insight into the propagation characteristics of electric fence networks, the Thesis presents a comprehensive mathematical model. The model uses the propagation properties of fence networks with frequency dependent distributed line parameters to obtain analytical solutions for the propagation function in the frequency-domain. As these analytical solutions are complex in nature, they are solved numerically to obtain time-domain solutions, the accuracy of which are verified through experiments and simulations. The mathematical tools and new technologies proposed in the thesis can be used to design electric fence systems that are more efficient and effective than the existing systems. In addition, the tools proposed are also expected to aid the design of electric fence based communication channels for intelligent farm management systems.
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Berber, Stevan M. 1950. "Methods and techniques for parameter and distribution function estimation in cascaded digital channels with and without memory." 2001. http://hdl.handle.net/2292/1958.
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Whole document restricted, see Access Instructions file below for details of how to access the print copy.Future telecommunication networks will employ digital transmission techniques. Such networks will provide a number of benefits including the ability to integrate voice and non-voice messages. The transmission channel of this network can be represented by a cascaded channel composed of a number of elementary channels connected in series. Therefore the modelling of such a channel is of particular interest. The influence of noise and other impairments in the cascaded binary channel cause errors which may be represented by a binary signal called the error sequence. Consequently, an important step in digital channel modelling is estimation of parameters and distribution functions which characterise the statistical properties of error sequences in the channel. Thus, the development of efficient methods for this estimation is a problem of long term interest which should be properly solved. This thesis presents methods and techniques for parameter (primarily the probability of error) and distribution function (primarily the error gap complementary distribution function) estimation using the error sequences obtained by measurement or simulation in elementary or cascaded channels. Theoretical analysis and testing confirm that it is possible to control the accuracy and reliability of estimation. Two principal and practical methods for the probability of error estimation are developed: the modified Monte Carlo method (MMC); and the method based on Chebyshev inequality (MCI). In contrast to the traditional Monte Carlo method based on classical statistics, the methods developed in this thesis aim to specify the sample size required to achieve the desired accuracy. The methods developed are based on the dependence of the sample size on the estimated value of a parameter being estimated. Hence the sample size is a random variable and the confidence limits factor (which specifies the width of confidence interval in respect to the estimated value) is a constant. Based on these methods, this thesis proposes and demonstrates two techniques for parameter estimation. The traditional Monte Carlo method has been primarily used for the probability of error estimation in channels without memory. In this thesis the capabilities of this method are extended to the case of estimating the probability of error in channels with memory and cascaded channels. However, even with this extension, this method is not practical due to its complexity and limitations on the qualification and quantification of the accuracy and reliability of estimation. Also, the extended method is unable to satisfactorily estimate the probability of error in cascaded channels with memory; nor could it improve the speed of the estimation process. Two methods and two techniques for distribution function estimation are developed in this thesis. They are demonstrated by estimating the error gap complementary functions of simulated data. For this purpose, simulators of binary channels with and without memory have been developed. The methods and techniques are characterised by their simplicity in application; ability to quantify the accuracy and reliability; time efficiency; and real time capability. The wider application of the methods and techniques developed in this thesis are demonstrated on three examples: a distribution function estimation using data obtained by indoor wideband radio propagation measurement; BER characteristics measurement; and measurement of the residual probability of error in transmission systems using error correcting codes. From the results obtained in the thesis some recommendations for future work in the field of digital channel modelling and simulation are discussed.
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Smith, Russell L. "Intelligent motion control with an artificial cerebellum." 1998. http://hdl.handle.net/2292/2130.
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This thesis describes a novel approach for adaptive optimal control and demonstrates its application to a variety of systems, including motion control learning for legged robots. The new controller, called “FOX”, uses a modified form of Albus’s CMAC neural network. It is trained to generate control signals that minimize a system’s performance error. A theoretical consideration of the adaptive control problem is used to show that FOX must assign each CMAC weight an “eligibility” value which controls how that weight is updated. FOX thus implements a kind of reinforcement learning which makes it functionally similar to the cerebellum (a part of the brain that modulates movement). A highly efficient implementation is described which makes FOX suitable for on-line control. FOX requires a small amount of dynamical information about the system being controlled: the system’s impulse response is used to choose the rules that update the eligibility values. A FOX-based controller design methodology is developed, and FOX is tested on four control problems: controlling a simulated linear system, controlling a model gantry crane, balancing an inverted pendulum on a cart, and making a wheeled robot follow a path. In each case FOX is effective: it associates sensor values with (and anticipates) the correct control actions, it compensates for system nonlinearities, and it provides robust control as long as the training is comprehensive enough. FOX is also applied to the control of a simulated hopping monoped, and a walking biped. FOX learns parameters that fine tune the movements of pre-programmed controllers, in a manner analogous to the cerebellar modulation of spinal cord reflexes in human movement. The robots are successfully taught how to move with a steady gait along flat ground, in any direction, and how to climb and descend slopes.
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Garnett, M. T. "Development and prototyping of a solid state lighting product for architectural and accent applications : a thesis presented in fulfilment of the requirements for the degree of Master of Product Development in Technology at Massey University, School of Engineering & Technology, Albany campus, New Zealand." 2009. http://hdl.handle.net/10179/1411.
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Far from being simply a necessary appliance to extend our day, artificial light has a great influence on human behaviour and wellbeing, perception of the surroundings and comfort. The energy needed for lighting is also a significant impact on our natural resources. For these two broad reasons lighting systems that improve the human visual and perceptual experience and reduce energy use are of widespread value. This work covers research into the application of LED technology as the next generation of mainstream lighting. It looks at the reasons why this technology is set to become the dominant way in which we light our lives, and the technical hurdles that are slowing this shift in lighting. It also presents the development, testing and prototyping of such an LED lighting product for use in the architectural market. This niche application is where LED lighting is currently most suited, due to the compactness, colour adjustability and lower colour rendering required. Establishing the technology here will help to gain consumer appreciation and acceptance of this beneficial and useful new paradigm in lighting. The design incorporates a shape that is pleasing to the eye with a simple oval profile. It was designed to be subtle and compact, blending into the ceiling as cleanly as possible. Practical testing on the finished prototype showed it to produce a wide range of colours and colour temperatures, while maintaining a safe LED temperature. The simplicity also makes the unit competitive in terms of cost.
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Edney, Daniel B. L. "Control and optimisation of coagulant dosing in drinking water treatment." 2005. http://hdl.handle.net/2292/1948.
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Whole document restricted, see Access Instructions file below for details of how to access the print copy.Correct coagulant dosage is necessary for the efficient operation of conventional drinking water treatment plants, yet no accurate or automated way of determining this exists. Streaming current (SC) is a measurement of charge on particles in water and is useful in feedback control of coagulant dosage. Analysis of the movement of change within a SC sensor can provide some explanation of its slow response, while signal processing utilising Fourier analysis improves the instrument's bandwidth. Presently inaccurate manual jar tests are the only way determine the SC required for best coagulation. An online automated jar tester is presented to improve on this. It uses an automatic sampling system that takes a sample from the process stream. An optimisation algorithm makes repeated step adjustments to the SC set point and gradually moves it in the direction of improving jar test results. The system was evaluated on both a small-scale model and a full-scale plant. Noise in the test measurements means the optimal set point cannot be located accurately enough, but the results indicate that this is possible. Greater accuracy would allow optimisation of turbidity and costs for multiple chemicals. A representative neural network model can be made of the dynamic relationship between coagulant dosage and streaming current in a scale model, with an alkali dosed to simulate a disturbance. In a rapid mixer, the measured response is significantly slower than the true response. Several common types of linear controller are designed and their performance at set point tracking and disturbance rejection is compared on this system. Model predictive control with a Kalman filter performs best in these tests, while the self-tuning regulator has benefits when the rate of set point change is slower. A non-linear feed-forward radial basis function network that adapts to the system's steady-state inverse can effectively augment a linear controller for this system. Adaptation rules based on vector eligibility are derived from dynamic back-propagation and extended to the general dynamic non-linear case. This can result in a useful and efficient feed-forward neural controller for dosing systems that can be represented by a Wiener model.
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Handley, P. G. "Spread spectrum switching: a low noise modulation technique for PWM inverter drives." 1990. http://hdl.handle.net/2292/2230.
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Three phase AC drives controlling cage induction motors have become widely accepted in industry, but one extant problem with this technology is that of increased acoustic noise emitted from the driven motor. This Thesis addresses the problem of the acoustic noise emitted from motors driven from voltage sourced PWM inverters and proposes a technique - Spread Spectrum Switching - for minimizing its effects. In the course of the work many other issues associated with real-time microprocessor-based PWM have also been advanced: • efficient microprocessor based PWM waveform generation, • harmonic analysis of generalized PWM waveforms, • compensation for the effects of power switch timing delays, and • compensation for the finite resolution of timers. The Thesis uses a variety of computational and analytical methods, backed by experimental observations, to quantify the improvement gained in each of these areas. Spread spectrum switching is a technique for eliminating the characteristically tonal structure of the acoustic noise emitted from a PWM inverter driven motor. Similar to the concept of spread spectrum communications, spread spectrum switching involves pseudo-randomly varying the instantaneous PWM switching frequency so that the energy of any PWM switching harmonics is dispersed over a wide bandwidth. This energy dispersion effectively eliminates any tonal components from the resultant motor acoustic noise while leaving the overall sound level largely unchanged; spread spectrum switching provides a significant qualitative yet minimal quantitative noise reduction. The PWM generation paradigm used in this Thesis is the recently reported Space Vector Modulation. A novel algorithm for microprocessor based space vector PWM generation is proposed, providing a basis for fast, efficient generation, even when overmodulating - a situation where many algorithms operate significantly more slowly. Furthermore, it is shown that the space vector method inherently generates a near optimum - in terms of motor harmonic loss - PWM waveform. However, when physically realized on a practical inverter such ideal PWM waveform s are corrupted by timing errors associated with both the inverter's power switches, predominantly the lockout time, and the finite resolution of hardware timers. Resolution corrected modulation is proposed for overcoming the problem of finite timer resolution and involves the use of integral feedback to account for any errors between ideal and physically realizable PWM switching times. This technique effectively provides 4 to 5 bits of added resolution to a given timer, allowing accurate waveform generation at low sinewave amplitudes and high switching frequencies using readily available, often microprocessor based, timers. Lockout times cause inverter output voltage errors, with consequent current zero crossing distortion, and a strategy for alleviating this problem is proposed and implemented in both a triangulation and space vector modulator. Two harmonic analysis techniques are proposed for analyzing PWM waveforms. The first technique is suitable for the analysis of regularly sampled PWM waveforms and has been used here to obtain closed form expressions for the harmonics of both space vector and asymmetrical triangulation PWM. These expressions show that PWM harmonics occur as a series of "combs" centered on multiples of the switching frequency. A second technique - the Directional Rotational Transform - is proposed for numerical analysis of general PWM waveforms. This technique uses an equivalent space vector representation of the PWM waveform, yielding the magnitude, phase and sequence (positive or negative) of the harmonics, and is useful in situations where each of the three phase waveforms is different, as in these cases Fourier Transform analysis of a single phase or line voltage only approximates the harmonics actually seen by the motor. The spectra generated using both these techniques compare favourably with those measured experimentally and, for synchronous PWM, those evaluated from Fourier Transforms. The culmination of modulation techniques presented in this Thesis yields a microprocessor based AC inverter drive featuring low acoustic noise emission at but a few kiloHertz switching rates and accurate PWM waveform generation using a single chip, low cost, micro-controller.
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Higgie, G. R. "Analysis of the families of variable length self synchronising codes called T-codes." 1991. http://hdl.handle.net/2292/2232.
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Studies of the families of variable length self-synchronising T-Codes are presented. The studies use Monte Carlo computer simulations to analyse the synchronising properties of the T-Codes and the relationships between these and their coding efficiency. Software and hardware implementations of the algorithms which are used to support these simulations are documented, and one of the encoding/decoding techniques presented is shown to be capable of operating at very high speed while being simple to implement. This technique is also shown to be applicable to the encoding and decoding of any variable length, exhaustive, instantaneous code. From the results of the simulations it is shown that some T-Codes consistently outperform others in the family with respect to their synchronising properties, and that the best of these codes have an average synchronisation delay of approximately 1.5 codewords. More importantly, it is shown that the T-Codes with the best synchronising performance are also the most efficient when encoding symbols from a specified information source, and that the coding efficiency of these codes is only nominally less than that of an optimal Huffman code generated for the source. A theoretical analysis of the synchronising properties is presented, and this is used to explain the relationships which exist between the average synchronisation delay and coding efficiency. These results are used to demonstrate that it is possible to choose a T-Code which has both the desirable properties of unrivalled synchronising performance and optimal coding efficiency, and guide-lines are given for choosing such a T-Code for a specified information source. This combination of a fast and simple encoding/decoding technique with codes which have unrivalled synchronising performance without sacrificing coding efficiency is offered as a solution to many of the problems normally associated with variable length coding techniques.
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Sowerby, K. W. (Kevin W. ). "Outage probability in mobile radio systems." 1989. http://hdl.handle.net/2292/2516.
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Outage probability calculations are presented for the analogue land mobile radio situation where in order to obtain satisfactory radio reception both a sufficient CNR and CIR need to be achieved simultaneously. Such calculations can be used in the design and analysis of mobile radio systems and may be particularly useful for investigating the effects of cochannel interference in cellular systems. The outage probability expressions are derived using previously reported statistical descriptions of mobile radio propagation. Attention is generally focussed on situations where signals suffer Rayleigh fading and/or lognormal shadowing. However calculations for Nakagami-m, Rice and Weibull fading are also considered. The rapid growth in cellular mobile radio systems has stimulated the development of outage probability calculations for multiple interferer situations. Previously, while single interferer situations had been treated exactly, multiple interferers had been treated by approximate methods. In this thesis exact multiple interferer outage probability expressions are presented for the Rayleigh fading and the joint 'fading and shadowing' (Suzuki) situations. Similar expressions, but for more limited cases, are also presented for lognormal and Nakagami-m statistics. Using results from these expressions the accuracies of several approximate outage probability methods are assessed. The exact outage probability expressions for multiple Suzuki interferer situations are closely related to those for multiple Rayleigh interferer situations. Indeed, the exact analytic expressions for Rayleigh statistics form an integral part of the corresponding outage probability expressions for Suzuki statistics. These latter expressions can be readily evaluated using Gauss-Hermite numerical integration. In order to demonstrate the use of such calculations for mobile radio system analysis several theoretical examples are presented. Outage probability calculations for multiple interferer systems which employ diversity reception as a means of improving communications reliability are considered. Similarly, the extension of outage probability concepts to digital systems is briefly outlined.
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Knowles, David John. "A separate texture/edge image coding system." 1990. http://hdl.handle.net/2292/2515.
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Digitised pictures have both cosmetic and scientific image aspects. This thesis presents an image coding system that compresses monochromatic digital image information in such a way that the cosmetic-or viewed-image aspects of a reconstructed picture are indistinguishable from the original to a (human) observer. The coding system is concerned with viewed aspects of digitised images and is based on a simplified 2-channel model of the human eye, with the image information being separated into slowly varying texture information and rapidly changing edge information corresponding to those two channels. Each of the two types of image data is coded using techniques suited to its individual characteristics. Texture information is coded using predictive waveform coding where the predictive filter coefficients are generated by linear predictive coding (LPC) techniques. Since the waveform prediction is not perfect, this thesis evaluates several different methods of differential pulse code modulation (DPCM) coding the residual prediction error. This signal is then used to improve the texture coding quality. Image edges are isolated from the digital image data by an asymptotically optimal edge detector known as the Laplacian of Gaussian (LOG) filter. Using two image edge models, the LOG isolated edges produce contours which are used to define edge position, shape, and "sharpness". The edge position data is then compressed using a chain-coding system. The thesis also considers the effect the edge characteristics have on the coding system and develops two methods for reducing the number of coded edges. Reconstruction of the coded image is in two parts corresponding to the two channels of the coding system. The texture information is reconstructed by predicting texture pixels and adding the decoded DPCM error signal. Edge information not contained in the texture coding channel is reconstructed using only edge information corresponding to the high spatial frequency channels of the human eye. These two channels are added together producing the final coded image reconstruction. Also considered are the effects of varying the original image sampling density. The 2-channel coding system is applicable to a wide variety of images, producing coded images with a high visual quality and coding bitrates as low as 0.6 bits/pixel (256 x 256 pixel images), while maintaining a relatively low computational overhead both at the encoder and the decoder.
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Huang, Dan 1980. "Robust control for uncertain networked control systems with random delays." 2008. http://hdl.handle.net/2292/3372.
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Networked control systems (NCSs) are a type of distributed control systems where sensors, actuators, and controllers are interconnected through a communication network. This system setup has the advantage of low cost, °exibility, and less wiring, but it also inevitably invites some delays and data loss into the design procedure. The focus of this thesis is to address the problem of analysis and design of networked control systems when the communication delays are varying in a random fashion. This random feature of the time delays is typical for commercially used networks, such as a DeviceNet (which is a controller area network (CAN)) and Ethernet network. Models for communication network delays are ¯rst developed, in which Markov processes are used to model these random network-induced delays. Based on such models, we establish novel methodologies for stability analysis, control with disturbance attenuation, and fault estimation for a class of uncertain linear/nonlinear uncertain NCSs with random communication network-induced delays in both sensor-to-controller and controller-to- actuator channels. Data packet dropouts in the communication channels also have been taken into consideration in the modelling and design procedure. The main technique used in this thesis is based on the Lyapunov-Razumikhin method, which results in delay-dependent controllers. We ¯rst consider the design prob- lems for uncertain linear NCSs. In this case, state feedback controllers and dynamic output feedback controllers are designed to satisfy both stability and disturbance at- tenuation requirements for this class of NCSs. Moreover, a robust fault estimator that ensures the fault estimation error is less than a prescribed performance level is designed. We further go on to address the control problems for uncertain nonlinear NCSs. The nonlinear plant is ¯rst described by the T-S fuzzy model. Based on this model, stability analysis, disturbance attenuation, and fault estimation problems are studied for uncer- tain nonlinear NCSs. It should be noted that system uncertainties, disturbances and noises are addressed in both cases. The existence of such controllers and fault estimators are given in terms of the solvability of bilinear matrix inequalities. Iterative algorithms are proposed to change this non-convex problem into quasi-convex optimization problems, which can be solved e®ectively by available mathematical tools. Finally, to demonstrate the e®ectiveness and advantages of the proposed design methodologies in this thesis, numerical examples are given in each designed control systems. The simulation results show that the proposed design methodologies can achieve the prescribed performance requirements.
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Murray, Phillip Edward. "Designing sustainable distributed generation systems for rural communities : an application of optimisation modelling and decision analysis to include sustainability concepts and uncertainty into design optimality : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Agricultural Engineering (Renewable Energy) at Massey University, Palmerston North, New Zealand." 2005. http://hdl.handle.net/10179/1566.
Full textAbstract:
The deregulation of the electricity supply industry in New Zealand has led to an increased level of interest in the security of electricity supply to rural communities. This in turn has led to questions about sustainable alternatives to conventional methods of electricity supply. A solution may be the adoption of sustainable community sized renewable energy (RE) based distributed generation systems. However, choosing between the myriad of possibilities requires much data and analysis. An accurate analysis of electricity load and RE resource matching is normally required. In most cases, this is an expensive and time-consuming assessment. In order to minimise these costs, and yet give due consideration to stakeholder preferences and technical uncertainty, a process incorporating the economic, social, environmental, and technical aspects of sustainable design in a relatively short timeframe will be required. This study developed such a method through the integrated use of the wind atlas assessment and analysis program (WAsP), the micropower optimisation model (HOMER), and three methods of decision analysis using Logical Decisions for Windows (LDW) software, which formed the decision analysis framework, SPiRAL (Sustainable Power in Rural Areas and Locations). The efficacy of the integrated use of the software in the SPiRAL framework was tested through two analyses using electricity load and RE resource data from a case study site. The first was an analysis using a full-year of data in a multi-method decision analysis process thus setting the framework in place. A further analysis then tested the minimum monitoring time required to obtain and analyse the data for modelling meaningful results. In both analyses, the results were ranked based on stakeholder preferences between the economic, social, environmental, and technical aspects of sustainable energy systems. The clear representation of the uncertainty of the electricity loads and the RE resources was paramount in the results. The short-term analysis results differed in small ways from the full-term, but were essentially similar. This study developed a decision analysis framework that delivered transparent results in a manner likely to instil insight and confidence in them, and this would provide the decision-maker with much valuable information on which to base their decision.
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Jeong, Jinsoo. "A kepstrum approach to real-time speech enhancement : thesis for the degree of Doctor of Philosophy, Information Engineering, Institute of Technology and Engineering, Massey University at Albany." 2007. http://hdl.handle.net/10179/1738.
Full textAbstract:
Content removed due to copyright: Conference proceedings (I) J. Jeong, and T.J. Moir, "Kepstrum approach to real-time speech enhancement methods using two microphones", Proceedings of the International Conference on Sensing Technology (ICST), pp 691-695, November 21-23, 2005, Palmerston North, New Zealand Conference proceedings (II) J. Jeong and T. J. Moir, "Two-microphone kepstrum approach to real-time speech enhancement methods" Proceedings of the IEEE International Conference on Engineering of Intelligent Systems (ICEIS), pp 392-397, April 22-23, 2006, Islamabad, Pakistan Conference proceedings (III) T. J. Moir and J. Jeong, "Identification of non-minimum phase transfer function components" Proceedings of the IEEE International Symposium on Signal Processing and Information Technology (ISSPIT), pp 380-384, August 27-30, 2006, Vancouver, CanadaThis research is mainly concerned with a robust method for an improved performance of a real-time speech enhancement and noise cancellation in a real reverberant environment. Therefore, the thesis titled, "A Kepstrum Approach to Real-Time Speech Enhancement" presents an application technique of a kepstrum method to a speech enhancement method. The kepstrum approach is based on a fundamental theory of kepstrum analysis, which gives a mathematical construct to the application of a speech enhancement. kepstrum analysis is applied to the system identification application of unknown acoustic transfer functions between two microphones. This kepstrum method provides a mathematical representation with FFT based processing and is independent of acoustic path model order. The front-end application of the kepstrum method to speech enhancement methods provides an improved performance in speech enhancement and noise cancellation with several favourable effects.
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Sudol, Peter. "Modelling and analysis of hydrogen-based wind energy transmission and storage systems : HyLink system at Totara Valley : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Energy Management at Massey University, Palmerston North, New Zealand." 2009. http://hdl.handle.net/10179/786.
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Distributed generation has the potential to reduce the supply-demand gap emerging in New Zealand’s electricity market. Thereby it can improve the overall network efficiency, harness renewable energy resources and reduce the need for upgrading of existing distribution lines. A typical New Zealand rural community consisting of three adjacent farms at Totara Valley near Woodville represents a demonstration site on distributed generation for Massey University and Industrial Research Limited. Local renewable energy resources are being used for the purpose of sustainable development. Alternative micro-scale technologies are being combined to achieve a valuable network support. This paper is an in-depth report on the implementation process of the HyLink system; a system which utilises hydrogen as an energy carrier to balance and transport the fluctuating wind power. The report documents its development from the laboratory stage to commissioning at Totara Valley, which was carried out under direction of Industrial Research Limited. The PEM electrolyser’s performance at different stack temperatures was investigated. It was found that hydrogen production increases at the same voltage with a higher stack temperature. This is due to the improved kinetics of the electrochemical reactions and decreased thermodynamic energy requirement for water electrolysis. The electrolyser efficiency measurement at the half of its maximal power input (247 W) resulted in 65.3%. Thereby the stack temperature attained less than half of the allowed limit of 80°C. The capture of the excess heat by insulation can improve the electrolyser’s efficiency. Pressure tests were performed on the 2 km long pipeline at Totara Valley using hydrogen and natural gas in order to test their permeability. The results were compared with previous studies at Massey University and with data obtained from the industry. The hydrogen permeability was measured to be 5.5 * 10[to the power of]-16 mol m m[to the power of]-2 s[to the power of]-1 Pa[to the power of]-1 for a 2 km MDPE pipe. This is about half the result obtained from previous studies on hydrogen permeability through MDPE at Massey University which was undertaken at room temperature. The reason for this discrepancy is likely to be the lower ambient temperature during the measurement at Totara Valley, which can be supported with the Arrhenius equation. It was furthermore measured that the power loss due to hydrogen diffusion through the pipeline walls during the fuel cell operation is about 1.5 W at the current system operation mode. A techno-economic analysis of the system was undertaken applying the micro-power optimisation software HOMER as a simulation tool. Two operation modes of the system were investigated, the load following and the peak demand compensating. The simulation results reveal that the durability and the cost of the electrochemical energy conversion devices; electrolyser and fuel cell, are the main hurdles which need to be overcome on the path in introducing hydrogen based energy systems like HyLink. Finally, economic optimisation modelling of the small-scale system by best component alignment was performed. It was found that the electrolyser capacity down-rating of 80% in relation to the wind turbine capacity, leads to a minimal system levelised cost. In addition to this, the impact of various wind turbine/electrolyser subsystems and pipeline storage capacities on the fuel cell capacity factor and on the system levelised cost in the load following operation mode was analysed. The outcomes can be useful for further HyLink related energy system planning.
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Cheng, Octavian. "Embedded speech recognition systems." 2008. http://hdl.handle.net/2292/3279.
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Apart from recognition accuracy, decoding speed and vocabulary size, another point of consideration when developing a practical ASR application is the adaptability of the system. An ASR system is more useful if it can cope with changes that are introduced by users, for example, new words and new grammar rules. In addition, the system can also automatically update the underlying knowledge sources, such as language model probabilities, for better recognition accuracy. Since the knowledge sources need to be adaptable, it is in°exible to statically combine them. It is because on-line modi¯cation becomes di±cult once all the knowledge sources have been combined into one static search space. The second objective of the thesis is to develop an algorithm which allows dynamic integration of knowledge sources during decoding. In this approach, each knowledge source is represented by a weighted ¯nite state transducer (WFST). The knowledge source that is subject to adaptation is factorized from the entire search space. The adapted knowledge source is then combined with the others during decoding. In this thesis, we propose a generalized dynamic WFST composition algorithm, which avoids the creation of non- coaccessible paths, performs weight look-ahead and does not impose any constraints to the topology of the WFSTs. Experimental results on Wall Street Journal (WSJ1) 20k- word trigram task show that our proposed approach has a better word accuracy versus real-time factor characteristics than other dynamic composition approaches.
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Bridger, Andrew B. "Increasing the spectral efficiency of contunous phase modulation applied to digital microwave radio : a resource efficient FPGA receiver implementation : [a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Electronics and Computer Systems Engineering at Massey University, Palmerston North, New Zealand ] EMBARGED UNTIL 1 JUNE 2012." 2009. http://hdl.handle.net/10179/1366.
Full textAbstract:
In modern point to point microwave radio systems used to backhaul cellular voice and data traffic, quadrature amplitude modulation (QAM) is the norm. These systems require a highly linear power amplifier which is expensive and has relatively low power efficiency. Recently, continuous phase modulation (CPM) has been deployed in this market. The CPM transmitted waveform has a constant envelope and so a non-linear RF power amplifier can be used. This significantly reduces cost and improves power efficiency. Two important disadvantages of CPM are receiver complexity and inferior spectral efficiency compared to QAM. This thesis demonstrates a 50% spectral efficiency improvement over an existing CPM configuration without loss of detection efficiency. This is achieved by moving to coherent demodulation and extending the duration of the CPM phase pulse to 3 symbol periods. This new CPM configuration of h=1/4, M=4, L=3, is evaluated against ETSI requirements for a 28 MHz channel carrying 24 E1 circuits. Simulation of the receiver floating point model demonstrates all requirements are met. The detection efficiency requirement is exceeded by 4.7 dB. Carrier recovery, phase and timing synchronisation are assumed to be ideal. The 50% increased symbol rate, coherent reception and a longer smoother phase pulse, conspire to increase receiver complexity substantially. The Viterbi algorithm is used to perform maximum-likelihood detection resulting in a 128 state trellis. This application has a stringent cost requirement that limits the implementation target to a Field Programmable Gate Array (FPGA) costing less than US$30. To demonstrate this demanding cost target is met, the two most computationally expensive receiver functions, the branch metric unit and path metric processing unit, are implemented in VHDL and targeted to a Xilinx Spartan 3A-DSP 1800 FPGA. The implementation uses 67% of the available logic resources, thus meeting the cost requirement. The branch metric unit is implemented using a distributed arithmetic technique that performs the equivalent of 27.6 giga-multiplies/s, consuming only 23% of the available FPGA logic cells. This is very efficient compared to a conventional approach using all the FPGA’s embedded multipliers which combined can only achieve 21 giga-multiplies/s. The Viterbi path metric processing unit is implemented using a more conventional state-parallel architecture. To reduce state metric routing complexity, states are grouped into radix-4 units comprising dual add-compare-select (ACS) units. By utilising a spare cycle in the deep ACS pipeline, each ACS unit processes two output state metrics, thus halving the number of ACS units required. This implementation uses 44% of the available FPGA resources and meets timing at 204.5 MHz, exceeding the throughput requirement of 54 Mbit/s.
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Jiang, Tianyang Ted. "The development of a pulse RF high power amplifier for a portable NMR spectrometer : a thesis presented in partial fulfillment of the requirement for the degree of Master of Engineering at Massey University." 2008. http://hdl.handle.net/10179/707.
Full textAbstract:
The RF high power amplifier is a key module in the NMR spectrometer. Robustness, lower power consumption, and small size are requirements. In this thesis, devices are studied and different design approaches are considered. New ideas are introduced, and simulations are used to show if it these work. A real prototype is developed. Results from the prototype are satisfactory and in good agreement with the simulation results. This allows for the possibility of a real portable NMR spectrometer 'Lapspec'. Points of note: • Feedback to stabilize amplifier, • Hard bias to improve rise time of pulse, • A rugged device is chosen, • Power limiter technology is used to avoid overdrive amplifier, • Lower value attenuator at output of final stage to reduce load VSWR, • Reason of spike is studied, the solution to reduce spike is given, • The reason of instability of amplifier with NMR load is analyzed, • A method is introduced to ensure there is no oscillation while the High Power Amplifier (HPA) is connected with the NMR probe.