The thesis presents models for short term planning (24 hours) of a hyro dominated hydrothermal power system. The purpose of the models is to minimizae the system operation costs to provide a forecasted load and keep enough spinning reserve. / This thesis presents models for short term planning (24 hours) of a hydro dominated hydrothermal power system. The purpose of the models is to minimize the system operation cost to provide a forecasted load and keep enough spinning reserve.   The thesis focuses on two issues in hydro power modelling. The first issue is the relationship between water discharged and power generated. This relationship is a non-linear and non-convex function. If the plant has several units, the efficiency of the plant will have local maximums, so called local best-efficiency points. The second issue is to take into account the cost of start-ups of hydro units in the planning.   The hydro model is mixed-integer. Discharg􀁐s are allowed at zero flow, the local best-efficiency points and on the continuous part between the local best-efficiency point with the highest flow and the point with maximum flow. This last continuous part is modelled as a linear function. In order to get data for the start-up cost a survey among the largest power producers in Sweden has been made, where three questions about start-ups of hydro power units has been asked: What causes the costs in the start-up?, How much does a start-up cost? and How do start-ups effect the short-term scheduling strategies of power producers in Sweden? The results show that a fair estimate of the start-up cost is about $3/MW nominal output. For the thermal plants a standard model with polynomial operation cost, start-up costs and ramp-rate constraints has been used. The model also includes the possibilities of purchasing and selling power to forecasted prices.   The planning problem is formulated as a mathematical programming problem. The solution technique uses Lagrange relaxation to decompose the problem into subproblems. There will be one subproblem for each hydro and thermal plant. In order to find good feasible solutions a heuristic technique to change the integer variables in the hydro system has been developed. The Lagrange multipliers are updated with the subgradient method.   The models are tested in three different load situations; a winter day (heavy load), an autumn day (medium load) and a summer day (light load). The result shows that the method gives near optimal schedules in reasonable computation time in cases with a normal part of the thermal units committed. The assumed start-up cost results in that hydro units almost never are started or stopped for one hour only. / <p>QC 20161206</p>

The UK and the world are moving away from central energy resource to distributed generation (DG) in order to lower carbon emissions. Renewable energy resources comprise a big percentage of DGs and their optimal integration to the grid is the main attempt of planning/developing projects with in electricity network. Feasibility and thorough conceptual design studies are required in the planning/development process as most of the electricity networks are designed in a few decades ago, not considering the challenges imposed by DGs. As an example, the issue of voltage rise during steady state condition becomes problematic when large amount of dispersed generation is connected to a distribution network. The efficient transfer of power out or toward the network is not currently an efficient solution due to phase angle difference of each network supplied by DGs. Therefore optimisation algorithms have been developed over the last decade in order to do the planning purpose optimally to alleviate the unwanted effects of DGs. Robustness of proposed algorithms in the literature has been only partially addressed due to challenges of power system problems such multi-objective nature of them. In this work, the contribution provides a novel platform for optimum integration of distributed generations in power grid in terms of their site and size. The work provides a modified non-sorting genetic algorithm (NSGA) based on MATPOWER (for power flow calculation) in order to find a fast and reliable solution to optimum planning. The proposed multi-objective planning tool, presents a fast convergence method for the case studies, incorporating the economic and technical aspects of DG planning from the planner‟s perspective. The proposed method is novel in terms of power flow constraints handling and can be applied to other energy planning problems.

The South African Construction Industry is one of the largest contributors to the gross domestic product of the country as well as to employment. It has, however, been experiencing significant challenges due to multifaceted factors. The main objective of this research was to identify the supply chain management constraints within the South African Construction Industry and how these can be overcome. This study is by nature descriptive and exploratory and contains qualitative elements. The problems were identified through a literature review, focused group discussions and interviews with major construction companies in South Africa. The findings also indicate that the main supply chain management constraints are to a greater extent internal and typical of supply chain methodologies and approaches. These constraints are among others the lack of coordination, collaboration and commitment between suppliers and clients within the supply chain, poor leadership in key areas of systems, design problems (many changes and inconsistent information), deficient internal and external communication and information transfer, inadequate management within the supply chain, mainly poor planning and control just to mention a few. A model based on supply chain system management as well as the Theory Of Constraints (TOC) has been developed that can be a useful tool to address the constraints in the construction sector. Originating from the study are applicable recommendations for the South African construction industry supply chains, covering key themes that have been articulated in the study, particularly benchmarking to the theory of constrains. Such recommendations include further research core components of supply chain such as, collaborations, logistics and how each of system components can be linked to performance of the supply chain management system.

The largely dominant adaptationist argument is currently used as the framework within which hominid brain evolution is explained; however these adaptationist explanations are inherently problematic and only suffice to ‘clutter’ our knowledge of the possible causes of hominid brain evolution. This study addresses the caveats observed in the fossil record and aims to assess the relative influence of structural laws of form, phylogenetic constraints, and adaptive factors during the course of primate and hominid brain evolution. A combination of methods such as variance partitioning, phylogenetic regression procedures and path analysis indicate that constraints have played a critical role in the scaling attributes of the primate and hominid brain. In particular, developmental constraints governing the scaling attributes of the skull and body are shown to explain up to 50 % of the variation in body mass whereas phylogenetic constraints are purported to have played a lesser role (i.e. 0.8 -3.6 %). In addition, the scaling attributes of neural and non-neural components of the cranial vault suggest a highly constrained suite of traits and suggest that as much as 96 % of the variation in both brain mass and residual endocranial space may be explained by correlated scaling with the cranial vault. Constraints are observed to be far more pliable than traditionally thought – a feature highlighted by intraspecific analyses of scaling attributes in humans. Low regression coefficients typical reported for intraspecific curves are shown to arise during development as greater variation in body parameters is allowed with advancing age. Grade shifts in the scaling of brain and body size for primates and other mammalian orders is also emphasised by this current study and it is argued that correlated changes between the brain and body size may not necessarily impact upon the ‘complexity’ of the neural system as the functional integrity may be maintained via higher output states initiated at certain levels of organisation such as at the level of the cortical area. Although constraints should rightfully be given greater coverage in explanations concerning hominid brain expansion, it is only through implementation of research protocols that take a pluralistic approach to an understanding of the role of both constraints and adaptation in the formation of the brain that our interpretation of the likely mechanism for hominid brain expansion may be understood.

Thesis advisor: Robert Murphy / The following three essays address two issues that have gained much recent attention among macroeconomists. The first essay - "International Policy Coordination: Policy Analysis in a Staggered Wage-setting Model" - deals with the incentives for countries to coordinate monetary and fiscal policies in an environment where the countries differ only in the length of the labor contracts which typify their respective economies. The second essay - "Tests for Liquidity Constraints: A Critique" and the third essay - "Liquidity Constraint Volatility: Evidence from Post-war Aggregate Time-series Data" - are tests of the importance and persistence of liquidity constraints in determining consumption behavior in the United States using micro-based data and aggregate timeseries data, respectively. / Thesis (PhD) — Boston College, 1988. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

There are as many perspectives in designing as there have been instances in which it has occured. In each instance, constraints will have invariably arisen in various forms, to the extent that designing and constraints are considered to be an inherently natural pairing. In addition, they are both affected by the challenges of complexity, amongst many others, which is especially compounded by an increasingly significant shift towards interdisciplinary methods and means of working. This has been in response to the influences and implications with regards to the integrated elements of sustainability and sustainable development. To this effect, the body of research effort presented in this thesis searches for a simpler perspective towards designing, to which constraint-based thinking can be applied. It explores the implications of interdisciplinarity in the context of sustainability and sustainable development. It also considers an example of design-based process within the built environment that is inclusive of multiple disciplines and therefore not only interdisciplinary, but also affected by complexity. In response to these instances of complex interdisciplinary designing, this thesis contributes an exploration of constraint-based thinking and the consideration of an approach which uses design objectives as optimisation constraints, from which a methodology has been created. Furthermore, this thesis demonstrates constraints as useful in understanding, especially in the context of problem structures and their respective design spaces. As a form of constraint, optimisation objectives are also presented in this thesis as a means of exposing and handling complexity when applied as constrained optimisation for focusing designing efforts. Above all, this thesis advocates the use of constraint-based thinking and simplicity towards enhancing and supporting designing process.

by Hui Kau Cheung Henry. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 107-112). / Abstracts in English and Chinese. / Abstract --- p.ii / Acknowledgments --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Organizations of the Thesis --- p.2 / Chapter 2 --- Background --- p.4 / Chapter 2.1 --- Constraint Satisfaction Problems --- p.4 / Chapter 2.1.1 --- Local Consistency Algorithm --- p.5 / Chapter 2.1.2 --- Backtracking Solver --- p.8 / Chapter 2.1.3 --- The Branch-and-Bound Algorithm --- p.10 / Chapter 2.2 --- Over-constrained Problems --- p.14 / Chapter 2.2.1 --- Weighted Constraint Satisfaction Problems --- p.15 / Chapter 2.2.2 --- Possibilistic Constraint Satisfaction Problems --- p.15 / Chapter 2.2.3 --- Fuzzy Constraint Satisfaction Problems --- p.16 / Chapter 2.2.4 --- Partial Constraint Satisfaction Problems --- p.17 / Chapter 2.2.5 --- Semiring-Based Constraint Satisfaction Problems --- p.18 / Chapter 2.2.6 --- Valued Constraint Satisfaction Problems --- p.22 / Chapter 2.3 --- The Theory of Constraint Hierarchies --- p.23 / Chapter 2.4 --- Related Work --- p.26 / Chapter 2.4.1 --- An Incremental Hierarchical Constraint Solver --- p.28 / Chapter 2.4.2 --- Transforming Constraint Hierarchies into Ordinary Con- straint System --- p.29 / Chapter 2.4.3 --- The SCSP Framework --- p.30 / Chapter 2.4.4 --- The DeltaStar Algorithm --- p.32 / Chapter 2.4.5 --- A Plug-In Architecture of Constraint Hierarchy Solvers --- p.34 / Chapter 3 --- Local Consistency in Constraint Hierarchies --- p.36 / Chapter 3.1 --- A Reformulation of Constraint Hierarchies --- p.37 / Chapter 3.1.1 --- Error Indicators --- p.37 / Chapter 3.1.2 --- A Reformulation of Comparators --- p.38 / Chapter 3.1.3 --- A Reformulation of Solution Set --- p.40 / Chapter 3.2 --- Local Consistency in Classical CSPs --- p.41 / Chapter 3.3 --- Local Consistency in SCSPs --- p.42 / Chapter 3.4 --- Local Consistency in CHs --- p.46 / Chapter 3.4.1 --- The Operations of Error Indicator --- p.47 / Chapter 3.4.2 --- Constraint Hierarchy k-Consistency --- p.49 / Chapter 3.4.3 --- A Comparsion between CHAC and PAC --- p.50 / Chapter 3.4.4 --- The CHAC Algorithm --- p.52 / Chapter 3.4.5 --- Time and Space Complexities of the CHAC Algorithm --- p.53 / Chapter 3.4.6 --- Correctness of the CHAC Algorithm --- p.56 / Chapter 4 --- A Consistency-Based Finite Domain Constraint Hierarchy Solver --- p.59 / Chapter 4.1 --- The Branch-and-Bound CHAC Solver --- p.59 / Chapter 4.2 --- Correctness of the Branch-and-Bound CHAC Solver --- p.61 / Chapter 4.3 --- An Example Execution Trace --- p.64 / Chapter 4.4 --- Experiments and Results --- p.66 / Chapter 4.4.1 --- Experimental Setup --- p.68 / Chapter 4.4.2 --- The First Experiment --- p.71 / Chapter 4.4.3 --- The Second Experiment --- p.94 / Chapter 5 --- Concluding Remarks --- p.103 / Chapter 5.1 --- Summary and Contributions --- p.103 / Chapter 5.2 --- Future Work --- p.104 / Bibliography --- p.107

All production machinery is designed with an inherent capability to handle slight variations in product. This is initially achieved by simply providing adjustments to allow, for example, changes that occur in pack sizes to be accommodated, through user settings or complete sets of change parts. By the appropriate use of these abilities most variations in product can be handled. However when extreme conditions of setups, major changes in product size and configuration, are considered there is no guarantee that the existing machines are able to cope. The problem is even more difficult to deal with when completely new product families are proposed to be made on an existing product line. Such changes in product range are becoming more common as producers respond to demands for ever increasing customization and product differentiation. An issue exists due to the lack of knowledge on the capabilities of the machines being employed. This often forces the producer to undertake a series of practical product trials. These however can only be undertaken once the product form has been decided and produced in sufficient numbers. There is then little opportunity to make changes that could greatly improve the potential output of the line and reduce waste. There is thus a need for a supportive modelling approach that allows the effect of variation in products to be analyzed together with an understanding of the manufacturing machine capability. Only through their analysis and interaction can the capabilities be fully understood and refined to make production possible. This thesis presents a constraint-based approach that offers a solution to the problems above. While employing this approach it has been shown that, a generic process can be formed to identify the limiting factors (constraints) of variant products to be processed. These identified constraints can be mapped to form the potential limits of performance for the machine. The limits of performance of a system (performance envelopes) can be employed to assess the design capability to cope with product variation. The approach is successfully demonstrated on three industrial case studies.

Bryan Chi-ho Lam. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 163-166). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Background --- p.4 / Chapter 2.1 --- Constraint Satisfaction Problems --- p.4 / Chapter 2.2 --- Systematic Search --- p.5 / Chapter 2.3 --- Stochastic Search --- p.6 / Chapter 2.3.1 --- Overview --- p.6 / Chapter 2.3.2 --- GENET --- p.8 / Chapter 2.3.3 --- CSVC --- p.10 / Chapter 2.3.4 --- Adaptive Search --- p.12 / Chapter 2.4 --- Hybrid Approach --- p.13 / Chapter 3 --- Progressive Stochastic Search --- p.14 / Chapter 3.1 --- Progressive Stochastic Search --- p.14 / Chapter 3.1.1 --- Network Architecture --- p.15 / Chapter 3.1.2 --- Convergence Procedure --- p.16 / Chapter 3.1.3 --- An Illustrative Example --- p.21 / Chapter 3.2 --- Incremental Progressive Stochastic Search --- p.23 / Chapter 3.2.1 --- Network Architecture --- p.24 / Chapter 3.2.2 --- Convergence Procedure --- p.24 / Chapter 3.2.3 --- An Illustrative Example --- p.25 / Chapter 3.3 --- Heuristic Cluster Selection Strategy --- p.28 / Chapter 4 --- Experiments --- p.31 / Chapter 4.1 --- N-Queens Problems --- p.32 / Chapter 4.2 --- Permutation Generation Problems --- p.53 / Chapter 4.2.1 --- Increasing Permutation Problems --- p.54 / Chapter 4.2.2 --- Random Permutation Generation Problems --- p.75 / Chapter 4.3 --- Latin Squares and Quasigroup Completion Problems --- p.96 / Chapter 4.3.1 --- Latin Square Problems --- p.96 / Chapter 4.3.2 --- Quasigroup Completion Problems --- p.118 / Chapter 4.4 --- Random CSPs --- p.120 / Chapter 4.4.1 --- Tight Random CSPs --- p.139 / Chapter 4.4.2 --- Phase Transition Random CSPs --- p.156 / Chapter 5 --- Concluding Remarks --- p.159 / Chapter 5.1 --- Contributions --- p.159 / Chapter 5.2 --- Future Work --- p.161

Mak, Wai Keung Terrence. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (p. 100-104). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Constraint Satisfaction Problems --- p.1 / Chapter 1.2 --- Weighted Constraint Satisfaction Problems --- p.2 / Chapter 1.3 --- Quantified Constraint Satisfaction Problems --- p.3 / Chapter 1.4 --- Motivation and Goal --- p.4 / Chapter 1.5 --- Outline of the Thesis --- p.6 / Chapter 2 --- Background --- p.7 / Chapter 2.1 --- Constraint Satisfaction Problems --- p.7 / Chapter 2.1.1 --- Backtracking Tree Search --- p.9 / Chapter 2.1.2 --- Local Consistencies for solving CSPs --- p.11 / Node Consistency (NC) --- p.13 / Arc Consistency (AC) --- p.14 / Searching by Maintaining Arc Consistency --- p.16 / Chapter 2.1.3 --- Constraint Optimization Problems --- p.17 / Chapter 2.2 --- Weighted Constraint Satisfaction Problems --- p.19 / Chapter 2.2.1 --- Branch and Bound Search (B&B) --- p.23 / Chapter 2.2.2 --- Local Consistencies for WCSPs --- p.25 / Node Consistency --- p.26 / Arc Consistency --- p.28 / Chapter 2.3 --- Quantified Constraint Satisfaction Problems --- p.32 / Chapter 2.3.1 --- Backtracking Free search --- p.37 / Chapter 2.3.2 --- Consistencies for QCSPs --- p.38 / Chapter 2.3.3 --- Look Ahead for QCSPs --- p.45 / Chapter 3 --- Quantified Weighted CSPs --- p.48 / Chapter 4 --- Branch & Bound with Consistency Techniques --- p.54 / Chapter 4.1 --- Alpha-Beta Pruning --- p.54 / Chapter 4.2 --- Consistency Techniques --- p.57 / Chapter 4.2.1 --- Node Consistency --- p.62 / Overview --- p.62 / Lower Bound of A-Cost --- p.62 / Upper Bound of A-Cost --- p.66 / Projecting Unary Costs to Cθ --- p.67 / Chapter 4.2.2 --- Enforcing Algorithm for NC --- p.68 / Projection Phase --- p.69 / Pruning Phase --- p.69 / Time Complexity --- p.71 / Chapter 4.2.3 --- Arc Consistency --- p.73 / Overview --- p.73 / Lower Bound of A-Cost --- p.73 / Upper Bound of A-Cost --- p.75 / Projecting Binary Costs to Unary Constraint --- p.75 / Chapter 4.2.4 --- Enforcing Algorithm for AC --- p.76 / Projection Phase --- p.77 / Pruning Phase --- p.77 / Time complexity --- p.79 / Chapter 5 --- Performance Evaluation --- p.83 / Chapter 5.1 --- Definitions of QCOP/QCOP+ --- p.83 / Chapter 5.2 --- Transforming QWCSPs into QCOPs --- p.90 / Chapter 5.3 --- Empirical Evaluation --- p.91 / Chapter 5.3.1 --- Random Generated Problems --- p.92 / Chapter 5.3.2 --- Graph Coloring Game --- p.92 / Chapter 5.3.3 --- Min-Max Resource Allocation Problem --- p.93 / Chapter 5.3.4 --- Value Ordering Heuristics --- p.94 / Chapter 6 --- Concluding Remarks --- p.96 / Chapter 6.1 --- Contributions --- p.96 / Chapter 6.2 --- Limitations and Related Works --- p.97 / Chapter 6.3 --- Future Works --- p.99 / Bibliography --- p.100