Low Pressure Die Casting (LPDC) process is one the most common casting process to produce structural automotive components, such as alloy wheels and suspension components. It has been identified that cavity filling and solidification process are two most critical aspects to produce premium quality casting components.During the solidification process of casting alloy, it is a well known phenomenon that metal experiences volumetric shrinkage due to its density difference between liquid and solid phase. When this volumetric shrinkage is not properly compensated, then a casting defect commonly known as solidification shrinkage occurs. The solidification shrinkage has very detrimental effects on structural integrity required for premium quality casting such as aluminium alloy wheels.Literature and practical experiences of foundry men show that it is critical to achieve unidirectional solidification pattern by avoiding an isolated hot spot in order to minimise the solidification shrinkage. However, it is found that the geometry of industrial casting applications is often constrained by other design factors that would not naturally avoid these isolated hot spots. The subject of this research, aluminium alloy wheels, is not excluded from this constraint.In aluminium alloy wheels, an isolated hot spot is commonly observed in an area known as rim and spoke junction due to its geometry constraints. Consequently, the solidification shrinkage is commonly experienced, which is undesirable due to its detrimental effects for the structural integrity of alloy wheels. In order to minimise the solidification shrinkage, forced cooling method is applied to avoid an isolated hot spot. The control of this forced cooling is achieved by cooling media, flow rate of cooling media and duration cooling circuit. Foundry experiments in industrial environment were conducted producing aluminium alloy wheels using commercially treated A356 (Al-Si) alloy, where different durations of cooling circuit were used to understand the sensitivity of solidification shrinkage formation to the duration of cooling circuit. This was followed by metallurgical structure analysis and numerical modelling to suggest the sensitivity of cooling circuit duration in controlling solidification shrinkage.The major finding conclusion of this research is that control of the shrinkage formation is not very sensitive to the duration cooling circuit. It is suggested that as casting solidifies initially from the mould wall, it retracts away from the cast-mould interface due to thermal contraction. Consequently, air gap is formed between casting and mould interface, creating an effective thermal resistance layer. Thereafter, heat transfer across the cast-mould interface is not sensitive to the change in the cooling channel which is a distance to the cast-mould interface.Some limitations of numerical modelling and metallurgical analysis were also identified during this research and recommendations were made to improve the accuracy of local hot spot prediction in production of aluminium alloy wheels. More specifically, numerical modelling of the effect of grain refinement and use of non homogeneous material property (particularly fraction of solid) for rapidly chilled area. Fraction of eutectic rather than secondary dendrites arm spacing is a proper microstructure parameter that can be used to locate the hot spot.

The purpose of accident investigation is the discovery of causal factors, so that they may be remedied, in order to avert the recurrence of accidents (ICAO, 1994). However, experience has shown that the present intuitive methods of analysis do not always achieve this aim. Investigation failure may come about because of failure to discover causal factors, or to devise effective remedies, or to persuade those in a position to act of the need to do so. Each of these types of failure can be made less likely by the use of formal analytical methods which can show whether information gathering has been incomplete, and point to the sources of additional information that may be needed. A formal analysis can be examined by formal logical tests. Also, the use of formal change mechanisms can not only devise changes likely to be effective, but can present these changes in such a way that the case for them is compelling. Formal methods currently available are concerned with what happened, and why it happened. To produce generic remedies which might avert future accidents of similar type, some formal change mechanism is needed. The Theory of Constraints has become widely adopted in business as a way of replacing undesirable effects with desired outcomes. The Theory of Constraints has not previously been used for safety investigation, and a principal object of this thesis is to see whether it can usefully be employed in this area. It is demonstrated that the use of formal methodology can bring to light factors which were overlooked during an official accident investigation, and can ‘tell the story’ in a more coherent manner than is possible with present methods. The recommendations derived from the formal analysis are shown to be generic in nature, rather than particular to the airline involved and the accident studied, and so could have a wider effect in improving safety.

在不完美的資本市場下，廠商的內外部融資彼此間為不完美的替代品，此時即使廠商有淨現值大於零的投資計畫，若外部資金因成本過高而無法取得，而其內部資金也已使用完畢，則廠商只好放棄此項投資計畫．此種因為資金不足而使投資計畫所受到的限制，我們稱為融資限制(Financing Constraints)． 對於面臨融資限制的廠商而言，由於其投資較依賴內部資金，故我們在其投資方程式中加入流動性變數時，此變數之係數應顯著．而對於未面臨融資限制的廠商而言，由於其投資較不依賴內部資金，故其投資方程式中流動性變數之係數應不顯著． 本研究即是使用八種廠商屬性，將廠商分成兩組，一組有面臨融資限制，一組未面臨融資限制，分別估計兩者加入流動性變數後的投資方程式，再觀察兩組廠商其流動性變數之係數是否有所差異，如此便可明瞭融資限制的存在是否能影響台灣廠商的投資．本研究使用的八種廠商屬性如下：(1)是否屬於集團．(2)所有權結構．(3)上市時間．(4)公司規模．(5)是否發放現金股利．(6)是否為製造業．(7)是否發行可轉換公司債．(8)是否發行商業本票．在實證結果上，雖然只有所有權結構

<p>"Taxation, Career Concerns and CEO Pay". This paper proposes a simple dynamic model of equilibrium CEO compensation. Motivated by the strengthened career incentives stemming from the fall in the top income tax rates over the past decades, I study the implications of a model where the quality of talent identification depends on how hard individuals work in order to be among the winners in the contest for managerial positions. It is shown how the compensation of CEOs can be interpreted in this light, across time, across industries, and across countries, and I provide some evidence showing that the predictions of the model are in line with several empirical developments over the past decades.</p><p>"Incentives under Communism: The Value of Low-Quality Goods". In this paper, I study how efficiently centrally planned regimes can provide incentives across different stages of economic development. In particular, I study the attractiveness of an incentive system based on exclusive provision of high-quality goods to high-ranked members of society. At low levels of economic development, a self-interested regime can exploit such an incentive system to reduce the cost of providing incentives. However, such an incentive system generally loses its attractiveness as the economy grows. The economic performance of the centrally planned economies is then analyzed in light of this result.</p><p>"The Business of Troubled Autocrats". Many autocrats control resource rents. Typically, they rely on these rents in order to buy political support. In this paper, I study how such autocrats behave in product and capital markets, in particular at times of financial distress. The main questions are: How does the asset position of an autocrat affect his behavior as a producer in a market with rents? From whom does the autocrat obtain financing in order to get out of difficulties? I show that when the asset position of the autocrat drops below a certain threshold, output drops below the level of a standard monopolist. Further, the autocrat can obtain less expensive financing domestically by exploiting the presence of vested interests, implying that there is zero foreign debt in equilibrium.</p>

<p>In the field of robotics there is a great interest in developing strategies and algorithms to reproduce human-like behavior. One can think of human-like machines that may replace humans in hazardous working areas, perform enduring assembly tasks, serve the elderly and handicapped, etc. The main challenges in the development of such robots are, first, to construct sophisticated electro-mechanical humanoids and, second, to plan and control human-like motor patterns.</p><p>A promising idea for motion planning and control is to reparameterize any somewhat coordinated motion in terms of virtual holonomic constraints, i.e. trajectories of all degrees of freedom of the mechanical system are described by geometric relations among the generalized coordinates. Imposing such virtual holonomic constraints on the system dynamics allows to generate synchronized motor patterns by feedback control. In fact, there exist consistent geometric relations in ordinary human movements that can be used advantageously. In this thesis the virtual constraints approach is extended to a wider and rigorous use for analyzing, planning and reproducing human-like motions based on mathematical tools previously utilized for very particular control problems.</p><p>It is often the case that some desired motions cannot be achieved by the robot due to limitations in available actuation power. This constraint rises the question of how to modify the mechanical design in order to achieve better performance. An underactuated planar two-link robot is used to demonstrate that springs can complement the actuation in parallel to an ordinary motor. Motion planning is carried out for the original robot dynamics while the springs are treated as part of the control action with a torque profile suited to the preplanned trajectory.</p><p>Another issue discussed in this thesis is to find stable and unstable (hybrid) limit cycles for passive dynamic walking robots without integrating the full set of differential equations. Such procedure is demonstrated for the compass-gait biped by means of optimization with a reduced number of initial conditions and parameters to search. The properties of virtual constraints and reduced dynamics are exploited to solve this problem.</p>

<p>Generating and stabilizing periodic motions in nonlinear systems is a challenging task. In the control system community this topic is also known as limit cycle control. In recent years a framework known as Virtual Holonomic Constraints (VHC) has been developed as one of the solutions to this problem. The aim of this thesis is to give an insight into this approach and its practical application.</p><p>The contribution of this work is primarily the experimental validation of the theory. A step by step procedure of this methodology is given for motion planning, as well as for controller design. Three particular setups were chosen for experiments: the inertia wheel pendulum, the Furuta pendulum and the two-link planar pendulum. These under-actuated mechanical systems are well known benchmarking setups for testing advanced control design methods.</p><p>Further application is intended for cases such as biped robot walking/running, human and animal locomotion analysis, etc.</p>

<p>I omvårdnaden av dementa uppstår ofta etiska överväganden där hänsyn skall tas till den demenssjuke, närstående, medboende samt lagar och riktlinjer. Sjuksköterskan ställs ofta inför svåra etiska situationer där beslut ska tas om eventuella tvångsåtgärder oberoende av vilket sorts stöd, moraliskt och/eller juridiskt, sjuksköterskan eventuellt har i sina beslut. Syftet med studien var att belysa sjuksköterskors upplevelser av etiska dilemman i demensvården i samband med olika tvångsåtgärder. Data samlades in via fokusgruppsintervjuer med sjuksköterskor (n=12) som ansvarade för personer med demenssjukdom inom särskilda boenden i en kommun i Norrland. En fallbeskrivning utgjorde grunden i fokusgruppsintervjuerna. Materialet analyserades via en kvalitativ manifest innehållsanalys. I resultatet framkom fyra kategorier. Etiska dilemman, etiskt förhållningssätt, rättsnormer och verklighet samt behov av stöd.  Sjuksköterskorna upplevde att de är ensamma i beslutsfattandet och behövde stöd i de svåra besluten kring åtgärder i olika etiska dilemman . Sjuksköterskorna upplevde närståendes delaktighet i vården av de dementa som ett bra och viktigt stöd och dialogen med närstående betonades. Det beskrevs också en känsla av stress då sjuksköterskan kommer i kläm mellan vårdpersonalens och de närståendes motstridiga krav som kan kännas svåra att tillmötesgå. En medvetenhet om de olika lagarna beskrevs men sjuksköterskorna upplevde det inte som ett etiskt dilemma att ibland behöva kringgå dem för att skydda den demente från skada eller lidande. Det skulle dock kännas bättre om de hade möjlighet att få stöd i lagen i sitt handlande. Den slutsats som vi drar är att sjuksköterskorna inte upplever några svårigheter att besluta om en tvångsåtgärd men behovet av stöd och handledning är stort.</p> / <p>Within the care of people with dementia ethical considerations often occurs and considerations has to be taken to the person with dementia, relatives, cohabitants and to laws and guidelines. Ethical dilemmas often occurs when the registered nurses (RNs) have to decide  whether or not to use constraints in the care, regardless of what kind of support these actions have in a moral or legal sense. The aim of this study was to describe the RNs experience of ethical dilemmas in relation to constraints in care of people with dementia. Data were collected in focus groups, with RNs (n=12) who worked in a municipal residential care for people with dementia in the north of Sweden. A case report initiated the interviews. Data were analyzed with qualitative content analysis. Four categories emerged. Ethical dilemmas, ethical approach, legal norms and reality, the need of support.  The RNs experienced loneliness in their decision making of interventions in different ethical difficult care situations and felt the need of support. They experienced that relatives are an important and a fine support in the care and the dialogue are pointed out as important. The RNs described feelings of stress when they were caught between conflicting demands from nursing staff and relatives. The RNs were aware of the laws related to health care, but they didn`t think of it as an ethical dilemma if they had to take sidestep from the law to protect the person with dementia from harm or misery. However they would feel better if they were supported by the law. <strong><em>Conclusion</em></strong><em>: </em>The RNs didn´t feel any difficulties if they had to decide to use constraints in the care of a person with dementia, but they are in need of support and coaching.</p>

<p>The complex work of designing new ASICs today and the increasing costs of time to market (TTM) delays are putting high responsibility on the research and development teams to make fault free designs. The main purpose of implementing a static rule checking tool in the design flow today is to find errors and bugs in the hardware definition language (HDL) code as fast and soon as possible. The sooner you find a bug in the design, the shorter the turnaround time becomes, and thereby both time and money will be saved.</p><p>There are a couple of tools in the market that performs static HDL analysis and they vary in both price and functionality. In this project mainly Atrenta Spyglass was evaluated but similar tools were also evaluated for comparison purpose.</p><p>The purpose of this master thesis was to evaluate the need of implementing a rule checking tool in the design flow at the Digital ASIC department PDU Base Station development in Kista, who also was the commissioner for this project. Based on the findings in this project it is recommended that a static rule checking tool is introduced in the design flow at the ASIC department. However, in order to determine which of the different tools the following pointers should be regarded:</p><p>• If the tool is only going to be used as for lint checks (elementary structure and code checks) on RTL, then the implementation of Mentors Design Checker is advised.</p><p>• If the tool is going to be used for more sophisticated structural checks, clock tree/reset tree propagation, code checks, basic constraints checks, basic Clock Domain Crossings (CDC) checks, then Synopsys LEDA is advised.</p><p>• If the tool is going to be used as for advanced structural checks, extensive clock tree/reset tree propagation, code checks, constraints checks, functional Design For Test (DFT) checks (as testmode signal propagation) and functional CDC checks on RTL as well as on netlist level, then Atrenta Spyglass is advised.</p><p>The areas regarding checks that could be of interest for Ericsson is believed to be regular lint checks for RTL (naming, code and basic structure), clock/reset tree propagation (netlist and RTL), constraints and functional DFT checks (netlist and RTL).</p>

<p>The software industry is facing a great challenge. While systems get more complex and distributed across the world, users are becoming more dependent on their availability. As systems increase in size and complexity so does the risk that some part will fail. Unfortunately, it has proven hard to tackle faults in distributed systems without a rigorous approach. Therefore, it is crucial that the scientific community can provide answers to how distributed computer systems can continue functioning despite faults.</p><p>Our contribution in this thesis is regarding a special class of faults which occurs whennetwork links fail in such a way that parts of the network become isolated, such faults are termed network partitions. We consider the problem of how systems that have integrity constraints on data can continue operating in presence of a network partition. Such a system must act optimistically while the network is split and then perform a some kind of reconciliation to restore consistency afterwards.</p><p>We have formally described four reconciliation algorithms and proven them correct. The novelty of these algorithms lies in the fact that they can restore consistency after network partitions in a system with integrity constraints and that one of the protocols allows the system to provide service during the reconciliation. We have implemented and evaluated the algorithms using simulation and as part of a partition-tolerant CORBA middleware. The results indicate that it pays off to act optimistically and that it is worthwhile to provide service during reconciliation.</p>

<p>Conformal field theories (CFT) constitute an interesting class of twodimensionalquantum field theories, with applications in string theoryas well as condensed matter physics. The symmetries of a CFT can beencoded in the mathematical structure of a conformal vertex algebra.The rational CFT’s are distinguished by the property that the categoryof representations of the vertex algebra is a modular tensor category.The solution of a rational CFT can be split off into two separate tasks, apurely complex analytic and a purely algebraic part.</p><p>The TFT-construction gives a solution to the second part of the problem.This construction gets its name from one of the crucial ingredients,a three-dimensional topological field theory (TFT). The correlators obtainedby the TFT-construction satisfy all consistency conditions of thetheory. Among them are the factorization constraints, whose implicationsfor boundary conditions are the main topic of this thesis.</p><p>The main result reviewed in this thesis is that the factorization constraintsgive rise to a semisimple commutative associative complex algebrawhose irreducible representations are the so-called reflection coefficients.The reflection coefficients capture essential information aboutboundary conditions, such as ground-state degeneracies and Ramond-Ramond charges of string compactifications. We also show that the annuluspartition function can be derived fromthis classifying algebra andits representation theory.</p>