Control energy consumption and system performance in vector control of voltage source converters

Power electronics plays an important role in the control and conversion of modern electric power systems. In particular, to integrate various renewable energies using DC transmissions and to provide more flexible power control in AC systems, significant efforts have been made in the modulation and control of power electronics devices. Pulse width modulation (PWM) is a well developed technology in the conversion between AC and DC power sources, especially for the purpose of harmonics reduction and energy optimization. As a fundamental decoupled control method, vector control with PI controllers has been widely used in power systems. However, significant power loss occurs during the operation of these devices, and the loss is often dissipated in the form of heat, leading to significant maintenance effort. Though much work has been done to improve the power electronics design, little has focused so far on the investigation of the controller design to reduce the controller energy consumption (leading to power loss in power electronics) while maintaining acceptable system performance. This paper aims to bridge the gap and investigates their correlations. It is shown a more thoughtful controller design can achieve better balance between energy consumption in power electronics control and system performance, which potentially leads to significant energy saving for integration of renewable power sources.

What is being taught in Religious Education classes in Northern Ireland and to what extent should states be concerned about regulation, quality and control of the subject?

This paper reports on a research project designed to discover what schools are teaching in Religious Education in Northern Ireland and what procedures are in place to maintain standards in the delivery of the subject. A search through literature shows that little research has been carried out to determine what is being taught in Religious Education in Northern Ireland. It also indicates that there are very weak systems of control to measure the effectiveness or quality of what is delivered. A survey of the websites of all Post-Primary schools in the region was used to provide some answers to the basic question of what is being taught in RE. Using content and discourse analysis of these alongside supporting documentary sources (textbooks and exam specifications), it is possible to get a clearer picture of how the Northern Ireland Core Syllabus for Religious Education and any additional curricular elements are delivered in schools. The findings show that a significant minority of schools do not publicly articulate what pupils do in religious education. In situations where the content of religious education is made clear, some definite trends are evident. Despite the existence of a statutory core syllabus, there is significant variation in what is taught in schools. The content is most divergent from the syllabus in relation to the teaching of World Religions at Key Stage 3 and at Key Stage 4 whole elements of the syllabus are neglected due to limited conformity between the syllabus and exam specifications. These results raise important questions about the systems of regulation and control of the subject in the region. In law the subject is exempt from formal inspection by the local inspection authority; instead, a form of inspection is allowed for by the Christian churches who design the syllabus, but it is a process that is either entirely neglected or entirely unreported in situations where it does occur. It is argued that these findings raise questions of more general concern for this and other regions in Europe where the teaching of religious education is largely unregulated. For example, to what extent should states take an interest in what is taught in religious education, how it is delivered, what values it promotes and how standards of teaching and learning in the subject are upheld?

The planning and control of operations involving the use of lethal force

This is an analysis of the case law of the European Court of Human Rights on the obligation on States to plan and control the use of potentially lethal force by their police and military personnel. It illustrates the Court's attachment to the strict or careful scrutiny test and suggests how the Court might want to develop its jurisprudence in the future.

Computational methods in the fractional calculus of variations and optimal control

The fractional calculus of variations and fractional optimal control are generalizations of the corresponding classical theories, that allow problem modeling and formulations with arbitrary order derivatives and integrals. Because of the lack of analytic methods to solve such fractional problems, numerical techniques are developed. Here, we mainly investigate the approximation of fractional operators by means of series of integer-order derivatives and generalized finite differences. We give upper bounds for the error of proposed approximations and study their efficiency. Direct and indirect methods in solving fractional variational problems are studied in detail. Furthermore, optimality conditions are discussed for different types of unconstrained and constrained variational problems and for fractional optimal control problems. The introduced numerical methods are employed to solve some illustrative examples.

Interactions of cetaceans with Spanish and Portuguese fisheries in Atlantic waters : costs, benefits and implications for management

With the aim to provide new insights into operational cetacean-fishery interactions in Atlantic waters, this thesis assesses interactions of cetaceans with Spanish and Portuguese fishing vessels operating in Iberian and South West Atlantic waters. Different opportunistic research methodologies were applied, including an interview survey with fishers (mainly skippers) and onboard observations by fisheries observers and skippers, to describe different types of interactions and to identify potential hotspots for cetacean-fishery interactions and the cetacean species most involved, and to quantify the extent and the consequences of these interactions in terms of benefits and costs for cetaceans and fisheries. In addition, the suitability of different mitigation strategies was evaluated and discussed. The results of this work indicate that cetaceans interact frequently with Spanish and Portuguese fishing vessels, sometimes in a beneficial way (e.g. cetaceans indicate fish schools in purse seine fisheries), but mostly with negative consequences (depredation on catch, gear damage and cetacean bycatch). Significant economic loss and high bycatch rates are, however, only reported for certain fisheries and associated with particular cetacean species. In Galician fisheries, substantial economic loss was reported as a result of bottlenose dolphins damaging artisanal coastal gillnets, while high catch loss may arise from common dolphins scattering fish in purse seine fisheries. High cetacean bycatch mortality arises in trawl fisheries, mainly of common dolphin and particularly during trawling in water depths below 350 m, and in coastal set gillnet fisheries (mainly common and bottlenose dolphins). In large-scale bottom-set longline fisheries in South West Atlantic waters, sperm whales may significantly reduce catch rates through depredation on catch. The high diversity of cetacean-fishery interactions observed in the study area indicates that case-specific management strategies are needed to reduce negative impacts on fisheries and cetaceans. Acoustic deterrent devices (pingers) may be used to prevent small cetaceans from approaching and getting entangled in purse seines and set gillnets, although possible problems include cetacean habituation to the pinger sounds, as well as negative side effects on non-target cetaceans (habitat exclusion) and fisheries target species (reduced catch rates). For sardine and horse mackerel, target species of Iberian Atlantic fisheries, no aversive reaction to pinger sounds was detected during tank experiments conducted in the scope of this thesis. Bycatch in trawls may be reduced by the implementation of time/area restrictions of fishing activity. In addition, the avoidance of fishing areas with high cetacean abundance combined with the minimization of fishery-specific sound cues that possibly attract cetaceans, may also help to decrease interactions. In large-scale bottom-set longline fisheries, cetacean depredation on catch may be reduced by covering hooked fish with net sleeves ("umbrellas") provided that catch rates are not negatively affected by this gear modification. Trap fishing, as an alternative fishing method to bottom-set gillnetting and longlining, also has the potential to reduce cetacean bycatch and depredation, given that fish catch rates are similar to the rates obtained by bottom-set gillnets and longlines, whereas cetacean by-catch is unlikely. Economic incentives, such as the eco-certification of dolphin-safe fishing methods, should be promoted in order to create an additional source of income for fishers negatively affected by interactions with cetaceans, which, in turn, may also increase fishers’ willingness to accept and adopt mitigation measures. Although the opportunistic sampling methods applied in this work have certain restrictions concerning their reliability and precision, the results are consistent with previous studies in the same area. Moreover, they allow for the active participation of fishers that can provide important complementary ecological and technical knowledge required for cetacean management and conservation.

Optimal dynamic control of laminated adaptive structures using a higher order model and a genetic algorithm

This paper deals with a finite element formulation based on the classical laminated plate theory, for active control of thin plate laminated structures with integrated piezoelectric layers, acting as sensors and actuators. The control is initialized through a previous optimization of the core of the laminated structure, in order to minimize the vibration amplitude. Also the optimization of the patches position is performed to maximize the piezoelectric actuator efficiency. The genetic algorithm is used for these purposes. The finite element model is a single layer triangular plate/shell element with 24 degrees of freedom for the generalized displacements, and one electrical potential degree of freedom for each piezoelectric element layer, which can be surface bonded or embedded on the laminate. To achieve a mechanism of active control of the structure dynamic response, a feedback control algorithm is used, coupling the sensor and active piezoelectric layers. To calculate the dynamic response of the laminated structures the Newmark method is considered. The model is applied in the solution of an illustrative case and the results are presented and discussed.

Core and patch position optimizations for vibration control of piezolaminated structures

This paper deals with a finite formulation baserd on the classical laminated plate tehory, for active control of thin late laminated structures with integrated piezoelectric layers, acting as sensors and actuators. The control is initialized through a previuos optimization of the core of the laminated structure, in order to minimize the vibration amplitude. Also the optimization of the patches position in performed to maximize the piezoelectric actuator efficiency. the simulating annealing mthod is used for these purposes. The finite element model is a single layer triangular nonconforming plate/shell element with 18 degrees of fredom for the generalized displacements, and one electrical potential degree of freedom for each piezoelectric element layer, wich can be surface bonded or imbedded on the laminate. To achieve a mechanism of active control of the structure dynamic response, a feedback control algorirhm is used, coupling the sensor and active piezoelectric layers. To calculate the dynamic response of the laminated structures the Newmark method is considered. The model is applied in the solution of an illustrative case and the results are presented and discussed.

Temperature, pH, and conductivity control of the nutrient solution of an hydroponic greenhouse

One of the aspects of modern agriculture is characterised by a culture without soil (hydroponic cultures). These culture techniques are identified by possessing automatic control systems to control the nutrient solution. In first hydroponic cultures this control was accomplished by “on- off” analog controllers that applied a single control law implemented in hardware. Therefore, the changes of the control law resulted in the change of all interface electronics. In digital control implemented by micro-controllers the alteration of such control law is easily performed by changing only a computer program, leaving untouched all the interface hardware. In this way, the use and substitution of the control strategy is improved, as well, the use of advanced control strategies.

Nuclear and mitochondrial control of the apoptosis machinery regulates neural stem cell fate

Tese de doutoramento, Farmácia (Bioquímica), Universidade de Lisboa, Faculdade de Farmácia, 2014

Control of endosomal Toll-like receptor (TLR) signaling by nanoparticles and applications in cancer therapy

Thesis (Ph.D.)--University of Washington, 2014

Internalising the external costs of light and heavy goods vehicle transport in London

Report produced as part of the Green Logistics project (EPSRC and Department for Transport funded). This report provides estimates of the total external costs of LGV and HGV operations in London. In 2006, total LGV and HGV activity imposed external costs of approximately £1.75-£1.8 billion using low, medium and high emission cost values. About 27 per cent of these costs were internalised by duties and taxes paid by LGV operators, compared with 26% in the case of HGVs. If congestion costs are excluded, taxes and duties paid by LGV operators are estimated to be 155% of LGVs' allocated infrastructural and environmental costs, compared with 85% in the case of HGVs. When using the medium emission cost values, LGVs accounted for 56% of these external costs in London and HGVs for 44%.

Logistics management and costs of biomass fuel supply

Discusses part of a project conducted by the authors into the logistics planning and management and costs of supplying biomass fuels to biomass-fired power stations in the UK. Defines biomass fuels and the reasons for the growth in interest in their use for electricity generation. The activities and parties involved in the biomass fuel supply chain are discussed together with the management of the chain in order to achieve smooth and consistent flow of biomass fuel to power stations. Explains the approach used to modelling the delivered costs of biomass fuels for four types of biomass fuel included in the project: forest fuel, short rotation coppice, straw and miscanthus. Comments are given on the environmental impacts of the fuel supply chains. The results indicate that straw supply systems are capable of producing the lowest delivered costs of the four fuels studied. Short rotation coppice and miscanthus, two new energy crops, are likely to have the highest delivered costs at present. This is due to the cost of growing these fuels and the financial incentives required by farmers to persuade them to grow these crops. Logistics costs (i.e. transport, storage and handling) are shown to represent a significant proportion of total delivered cost in biomass supply. Careful supply chain planning and logistics management will be of central importance to the success of the biomass industry.

Internalising the external costs of light and heavy goods vehicles in London

This report provides estimates of the total external costs of LGV and HGV operations in London. In 2006, total LGV and HGV activity imposed external costs of approximately £1.75-£1.8 billion using low, medium and high emission cost values. About 27 per cent of these costs were internalised by duties and taxes paid by LGV operators, compared with 26% in the case of HGVs. If congestion costs are excluded, taxes and duties paid by LGV operators are estimated to be 155% of LGVs' allocated infrastructural and environmental costs, compared with 85% in the case of HGVs. When using the medium emission cost values, LGVs accounted for 56% of these external costs in London and HGVs for 44%.