Energy management strategies for charge sustaining hybrid electric vehicles reduce fuel power consumption from the engine and electric power consumption from the motor while meeting output power demand. The equivalent consumption minimization strategy is a real time control strategy which uses backward facing models and an equivalence ratio to calculate the lowest total fuel power consumption. The equivalence ratio quantifies the fuel power to battery power conversion process of the hybrid electric vehicle components and therefore quantifies electric power consumption in terms of fuel power consumption. The magnitude of the equivalence ratio determines when the hybrid electric vehicle commands a conventional, electric, or hybrid mode of operation. The equivalence ratio therefore influences the capability of the control strategy to meet charge sustaining performance. Willans line models quantify the input power to output power relationship for powertrain and drivetrain components with a linear relationship and a constant offset. The hybrid electric vehicle model performance is characterized using three Willans line models in the equivalent consumption minimization strategy. The slope of the Willans line models, or marginal efficiency, is used to generate a single equivalence ratio which quantifies the fuel to battery energy conversion process for the hybrid electric vehicle. The implementation of a Willans line based equivalent consumption minimization strategy reduces total fuel power consumption while achieving charge sustaining performance over mild and aggressive drive cycles. / Master of Science / The charge sustaining hybrid electric vehicle in this paper generates output power with an internal combustion engine powered by a fuel tank and an electric traction motor powered by a battery pack. Hybrid electric vehicle energy management strategies generate torque commands to meet output power demand based on the minimum total input power from both the fuel tank and battery pack. Willans line models simplify the energy management strategy by quantifying the output power to input power relationship, or efficiency, of each component with a linear slope and constant offset. The use of Willans line models quantifies the efficiency of the hybrid electric vehicle with three linear relationships. Energy management strategies also ensure the battery pack starts and ends at the same operating condition to maintain charge sustaining performance. Charge sustaining hybrid electric vehicles therefore use the battery pack as an energy buffer and do not need to be charged by an external power supply since all energy comes from fuel. The output to input power relationship of Willans line models quantifies the power conversion of the hybrid electric vehicle and coupled to a term which accounts for changes in the battery pack. The use of Willans line models in hybrid electric vehicles effectively generates torque commands to the engine and motor while improving fuel economy and maintaining charge sustaining performance.

This research explores the idea of developing an optimal path generator that can be used in conjunction with a feedback steering controller to automate track testing experiment. This study specifically concentrates on applying optimization concepts to generate paths that meet two separate objective functions; minimum time and maximum tire forces. A three-degree-of freedom vehicle model is used to approximate the handling dynamics of the vehicle. Inputs into the vehicle model are steering angle and longitudinal force at the tire. These two variables approximate two requirements that are essential in operating a vehicle. The Third order Runge-Kutta integration routine is used to integrate vehicle dynamics equations of motion. The Optimization Toolbox of Matlab is used to evaluate the optimization algorithm. The vehicle is constrained with a series of conditions, includes, a travel within the boundaries of the track, traction force limitations at the tire, vehicle speed, and steering. The simulation results show that the optimization applied to vehicle dynamics can be useful in designing an automated track testing system. The optimal path generator can be used to develop meaningful test paths on existing test tracks. This study can be used to generate an accelerated tire wear test path, perform parametric study of suspension geometry design using vehicle dynamics handling test data, and to increase repeatability in generating track testing results. <i> Vita removed at author's request. GMc 3/13/2013</i> / Master of Science

Clock scheduling is studied to improve the performance of synchronous sequential circuits. The performance improvement covers the optimization of the clock frequency and the peak power consumption, separately. For clock period minimization, cycle stealing method is utilized, in which the redundant cycle time of fast combinational logic is transferred to slower logic by proper clock skew adjustment of registers. The clock scheduling system determines the minimum clock period that a synchronous sequential circuit can operate without hazards. The timing of each register is adjusted for operation with the minimum clock period. The dependence of the propagation delays of combinational gates on load capacitance values are modeled in order to increase the accuracy of the clock period minimization algorithm. Simulation results show up to 45% speed-up for circuits that are scheduled by the system. For peak power minimization, the dependence of the switching currents of circuit elements on the load capacitance values are modeled. A new method, namely the Shaped Pulse Approximation Method (SPA), is proposed for the estimation of switching power dissipation of circuit elements for arbitrary capacitive loads. The switching current waves can accurately be estimated by using the SPA method with less than 10% normalized rms error. The clock scheduling algorithm of Takahashi for the reduction of the peak power consumption of synchronous sequential circuits is implemented using the SPA method. Up to 73% decrease in peak power dissipation is observed in simulation results when proper clock scheduling scheme is applied to test circuits.

Every time a good is produced, waste occurs as an unwanted by-product. Waste has become a real environmental issue across the world, contributing to the degradation of the environment and human health. As part of a local and international effort to lessen industrial pollution, a concept to reduce waste production at source was introduced to companies in the early 1990s. Pioneered in the Netherlands and the United Kingdom (UK), this concept has been termed 'waste minimisation'. Waste minimisation is achieved by implementing changes to business practices and processes, such as improved housekeeping (e.g. prevention of spills), and changes to equipment that is less wasteful. It is often undertaken by a group of organisations, including for example service providers, manufacturing companies and regulators that join a waste minimisation club (WMC). This provides an opportunity in which training can be received by, waste minimisation assessments made on, and information and ideas about waste reduction at source exchanged by member companies. WMCs have been used successfully in Europe to achieve waste minimisation in industry and residential communities. This study aims to contribute to the development of a sustainable WMC model in South Africa. It analyses the WMC support structures in South Africa and compares them to support structures offered in the UK. This offers a point of reference from which the impact of South African support structures on WMCs in general, and the Pietermaritzburg Waste Minimisation Club (PWMC) in particular, can be established. The PWMC consists of small and medium companies across sectors, each with less than 200 employees and with an annual turnover less than 40 million rand. The club was initiated by the Pollution Research Group of the University of KwaZulu-Natal (UKZN). It was the first of its kind in South Africa, having been facilitated on a small budget by staff and students from the UKZN. The study found that the self-help approach adopted by the PWMC was only partially successful. The PWMC was successful in terms of raising awareness of its members to waste minimisation issues. The study also found that member companies, both from the PWMC and WMCs generally, need to be shown in practical terms that 2 waste minimisation can result in financial savings before management buy-in can be attained. If more University manpower had been allocated, in the form of students for instance, to identify and orchestrate implementation of sustainable waste minimisation solutions, the PWMC member adoption rate of waste minimisation may have been raised. The small PWMC budget may have made this impossible, however. Lack of funding may also have prevented facilitators putting together a large support team, as has been done for a similar and more successful project in England. This demonstrates that self-help WMCs need an initial funding boost to be successful. This funding should be invested in gaining buy-in from company personnel rather than to drive the waste minimisation process on behalf of member companies. Driving waste minimisation on behalf of companies or 'hand-holding' leads to a passive acceptance of waste minimisation as is currently the case in South Africa, as well as 'shirking' as has been observed in the UK. Such a facilitated self-help approach can then lay the basis for WMCs, which use the support infrastructure established by their predecessors. Studies of WMCs in England and Wales based on a self-help approach showed that they achieved financial savings that are comparable to those in demonstration clubs. The promotion of such sustainable WMCs in South Africa needs to be performed by a central support agency such as the British Envirowise. Envirowise was seen to successfully promote waste minimisation among those it reached. However, it reached only a small percentage of overall industry. A successful South African agency therefore needs to promote itself effectively and nation-wide. A successful South African Envirowise organisation should also facilitate the creation of WMCs by leading a forum of industry, service providers, higher education and waste minimisation champions of proven worth, to create an action plan for WMC development for each province. Each province would then allocate funds for a waste minimisation champion who, in conjunction with the local development agency, would create a provincial action plan for the development of facilitated self-help WMCs. The local support and expertise recruited to form and manage WMCs would decrease costs and leverage income. This kind of support agency needs to be upheld by waste management legislation based on the concept of sustainable development, recognising the need for environmental protection alongside that of economic growth. To date no such legislation is in place in South Africa. It is hoped that the White Paper on Integrated Pollution and Waste Management, which endorses the principle of sustainable development alongside with the necessity to reduce waste at source, will form the basis for a successful South African WMC culture. / Thesis (M.Env.Dev.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

No description available.

Cette thèse étudie différents problèmes de minimisations avec des fonctions de régularisations qui promeuvent la parcimonie. Plus précisément, on souhaite reconstruire une image, que l'on suppose parcimonieuse et qui a subit une transformation après un opérateur linéaire, à l'aide de problèmes de minimisations. Dans ce manuscrit, on s'intéressera plus particulièrement à la minimisation l1 synthèse, analyse et bloc qui sont très utilisées pour reconstruction une image que l'on sait parcimonieuse. Ces minimisations produisent en pratique des résultats convaincants qui n'ont été compris théoriquement que récemment. Les différents travaux sur le sujet mettent en évidence le rôle d'un vecteur particulier appelé certificat dual. L'existence d'un certificat dual permet à la fois d'assurer la reconstruction exacte d'une image dans le cas où il n'y a pas de perturbations et d'estimer l'erreur de la reconstruction en présence de perturbations. Dans nos travaux, nous allons introduire l'existence d'un certifical dual optimal pour la minimisation l1 synthèse qui minimisent l'erreur de reconstruction. Ces résultats ayant une forte interprétation géométrique, nous avons développé un critère identifiabilité, c'est à dire que ce critère assure que l'image recherchée est l'unique solution du problème de minimisation. Ce critère permet d'étendre nos travaux à la minimisation l1 analyse, l1 bloc et à d'autres cas. / This thesis studies different minimization problems with sparses based regularization. More precisely, we want to reconstruct a sparses image, which undergone a linear transformation, with minimization problems. In this manuscript, we will be focused on l1 synthesis, analysis and block minimization which are widely used in sparse approximations. These problems offer competitive results which are theorietical understood only recntly. Different studies on the subject emphasized the contribution of a particular vector called dual certificate. The existence of this dual certificate allows simultaneously to guarantee the exact recovey of an image in noiseless case and to estimate the noise robustness in noisy case. In this work, we introduce eth existence of an optimal dual certificate for the l1 synthesis minimization which minimizes the reconstruction error. As those results have a strong geometrical interpretation, we develop an identifiability criterion which ensures the uniqueness of a solution. This criterion generalizes the work on l1 synthesis minimization tothe analysis case, block case and others.

Distributed event processing systems suffer from poor scalability and inefficient resource usage caused by load distributions typical in real-world applications. The results of these shortcomings are availability issues, poor system performance, and high operating costs. This thesis proposes three remedies to solve these limitations in content-based publish/subscribe, which is a practical realization of an event processing system. First, we present a load balancing algorithm that relocates subscribers to distribute load and avoid overloads. Second, we propose publisher relocation algorithms that reduces both the load imposed onto brokers and delivery delay experienced by subscribers. Third, we present ``green" resource allocation algorithms that allocate as few brokers as possible while maximizing their resource usage efficiency by reconfiguring the publishers, subscribers, and the broker topology. We implemented and evaluated all of our approaches on an open source content-based publish/subscribe system called PADRES and evaluated them on SciNet, PlanetLab, a cluster testbed, and in simulations to prove the effectiveness of our solutions. Our evaluation findings are summarized as follows. One, the proposed load balancing algorithm is effective in distributing and balancing load originating from a single server to all available servers in the network. Two, our publisher relocation algorithm reduces the average input load of the system by up to 68%, average broker message rate by up to 85%, and average delivery delay by up to 68%. Three, our resource allocation algorithm reduces the average broker message rate even further by up to 92% and the number of allocated brokers by up to 91%.

Distributed event processing systems suffer from poor scalability and inefficient resource usage caused by load distributions typical in real-world applications. The results of these shortcomings are availability issues, poor system performance, and high operating costs. This thesis proposes three remedies to solve these limitations in content-based publish/subscribe, which is a practical realization of an event processing system. First, we present a load balancing algorithm that relocates subscribers to distribute load and avoid overloads. Second, we propose publisher relocation algorithms that reduces both the load imposed onto brokers and delivery delay experienced by subscribers. Third, we present ``green" resource allocation algorithms that allocate as few brokers as possible while maximizing their resource usage efficiency by reconfiguring the publishers, subscribers, and the broker topology. We implemented and evaluated all of our approaches on an open source content-based publish/subscribe system called PADRES and evaluated them on SciNet, PlanetLab, a cluster testbed, and in simulations to prove the effectiveness of our solutions. Our evaluation findings are summarized as follows. One, the proposed load balancing algorithm is effective in distributing and balancing load originating from a single server to all available servers in the network. Two, our publisher relocation algorithm reduces the average input load of the system by up to 68%, average broker message rate by up to 85%, and average delivery delay by up to 68%. Three, our resource allocation algorithm reduces the average broker message rate even further by up to 92% and the number of allocated brokers by up to 91%.

Environmental legislation is becoming more stringent as people are realising the need for conservation and a reduction of environmental degradation in order to facilitate sustainable development. To ease legislative pressures, companies need to work together in symbiotic networks, whereby co-operation between companies results in far more innovative practices than if the companies acted individually. Success in an industrial network is largely dependent on cleaner production, where industries seek to redirect from waste treatment to waste minimisation. Cleaner production has already received international recognition and waste minimisation initiatives have been used as a tool of cleaner production. Two polluting industrial sectors within South Africa, the textile and metal finishing sectors, were chosen to investigate waste minimisation concepts. One company from each sector was used as a case study. The dissertation followed company network identification, potential to participate within an industrial symbiotic network, and waste minimisation opportunities. Suppliers and buyers, up and down the product line were identified. Relationships with these partners should be advanced such that environmental concerns are at the forefront of any decision-making. In light of developing industrial networks and maintaining symbiotic relationships, the company's potential was investigated by interviewing employees of various ranks. Both companies were partially suited to participate within an industrial symbiotic network and company-specific barriers were identified, such as ineffective internal communication. The waste minimisation investigation followed a four-phase approach of planning and organisation; pre-assessment; assessment; and feasibility study. In both the companies investigated, water savings were identified as the waste minimisation focus area with potential for improvement. In total, potential water savings of over R80 000 per annum were identified. In the textile company, the weaving department and bleach house were further investigated. Cloth weaving errors were attributed to machine stops, as each stop has the potential to result in a cloth fault. In the bleach house the potential existed to reduce the number of rinse tanks. Although a modem and automated process, the plating plant in the metal finishing company was identified as having potential waste minimisation opportunities. Of particular interest was the reduction of solution carry over from the plating tanks into subsequent tanks. Extended drip times were investigated. Additional waste minimisation opportunities included repairing pipe leaks, replacing the degreasing solvent, trichloroethylene, with a less harmful cleaning agent and establishing a symbiotic relationship with the oil supplier, Castrol. Over and above the main waste minimisation opportunities highlighted, other recommendations and potential savings were identified. Each case study emphasises that simple waste minimisation initiatives, without expending capital, reduce demands on natural resource, such as water, and benefit the company financially. Successful waste minimisation leads to further cleaner production initiatives, which may then initiate better network interactions with the further potential of promoting sustainable development. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2002.

Take care how you place your moccasins upon the earth, step with care, for the faces of the future generations are looking upfrom the earth waitingfor their turnfor life - Lyoru, 1988 Increasing levels of pollution and the increase in demand for water and other resources by industry led to a number of policies and regulations being developed and revised in South Africa. According to the Constitution of the Republic of South Africa (Act 108 of 1996), everyone has the right to an environment that is not harmful to health or wellbeing. In order to have the environment protected and sustained for future use, it became necessary to move away from the traditional fragmented approach to pollution and waste management and focus on an integrated strategy aimed at achieving a balance between ecological sustainability and socioeconomic development. In the Durban Metropolitan Area (DMA) , the Durban Metropolitan Council (Metro) incorporated pollution prevention in their bylaws, which contained stringent discharge limits for heavy metal concentrations. This posed a potential problem for metal fmishers who were concerned about complying with these discharge standards. In addition, the metal finishing industry was considered to be a significant contributor to the pollution load in the DMA, and therefore needed to find suitable solutions to dealing with environmental problems, especially waste management. Waste minimisation was believed to be a good tool for this industry to utilise in order to reduce its pollution load. It was seen from the literature and case studies from international initiatives that waste minimisation results in an improvement in process efficiency and reductions in production costs and environmental impacts, generally at minimal costs. A waste minimisation club was initiated for the metal finishing industry in the DMA in June 1998. The club consisted of twenty-nine members of which the majority were small and medium sized companies. The club was run over a period of thirty months. A core group of sixteen companies actively participated in the activities of the club. During the period of investigation, a total of 391 waste minimisation options were identified for club members and 147 of these options were implemented. This resulted in a total financial saving in excess of R 4 million for the duration of the club's existence. The saving represents combined savings in water, chemicals, metals, energy, effluent treatment, and waste disposal. Corresponding environmental benefits were achieved including a reduced demand for water, reduced toxicity of effluent from chemical and metal reduction, and a reduction in energy requirements. Four companies were investigated in detail and presented as case studies. These companies showed that the payback on implementing waste minimisation options was mostly immediate. The size of the companies was not critical in determining the level of success from running waste minimisation programmes. Success depended mainly on commitment from companies and motivation of project champions. It was found that the greatest barriers to implementing waste minimisation, as identified by companies, were a lack of time, resources, and commitment. Companies joined the club mainly for benefit of reducing costs and complying with legal standards. Aside from successfully raising awareness and promoting the concept of waste minimisation, the waste minimisation club also resulted in an improvement in the relationship between the metal finishing industry and the Metro, and among club members. Based on the results achieved by club members, and from managing the club, it was evident that the club was effective in promoting waste minimisation in industry. For the future running of clubs, it is recommended that waste minimisation assessment training be given to all employees of a company. It would also be more useful if companies reported savings on a more regular basis and more formally. In addition it is recommended that club membership should be limited to between ten and fifteen companies to facilitate improved management of the club. / Thesis (M.Sc.Eng.)-University of Natal,Durban, 2002.