26,549 research outputs found

    Optimizing a multiple objective surgical case scheduling problem.

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    The scheduling of the operating theater on a daily base is a complicated task and is mainly based on the experience of the human planner. This, however, does not mean that this task can be seen as unimportant since the schedule of individual surgeries influences a medical department as a whole. Based on practical suggestions of the planner and on real-life constraints, we will formulate a multiple objective optimization model in order to facilitate this decision process. We will show that this optimization problem is NP-hard and hence hard to solve. Both exact and heuristic algorithms, based on integer programming and on implicit enumeration (branch-and-bound), will be introduced. These solution approaches will be thoroughly tested on a realistic test set using data of the surgical day-care center at the university hospital Gasthuisberg in Leuven (Belgium). Finally, results will be analyzed and conclusions will be formulated.Algorithms; Belgium; Branch-and-bound; Constraint; Data; Decision; Experience; Healthcare; Heuristic; Integer; Integer programming; Model; Optimization; Order; Processes; Real life; Scheduling; University;

    Resource-constrained project scheduling.

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    Abstract: Resource-constrained project scheduling involves the scheduling of project activities subject to precedence and resource constraints in order to meet the objective(s) in the best possible way. The area covers a wide variety of problem types. The objective of this paper is to provide a survey of what we believe are important recent in the area . Our main focus will be on the recent progress made in and the encouraging computational experience gained with the use of optimal solution procedures for the basic resource-constrained project scheduling problem (RCPSP) and important extensions. The RCPSP involves the scheduling of a project its duration subject to zero-lag finish-start precedence constraints of the PERT/CPM type and constant availability constraints on the required set of renewable resources. We discuss recent striking advances in dealing with this problem using a new depth-first branch-and-bound procedure, elaborating on the effective and efficient branching scheme, bounding calculations and dominance rules, and discuss the potential of using truncated branch-and-bound. We derive a set of conclusions from the research on optimal solution procedures for the basis RCPSP and subsequently illustrate how effective and efficient branching rules and several of the strong dominance and bounding arguments can be extended to a rich and realistic variety of related problems. The preemptive resource-constrained project scheduling problem (PRCPSP) relaxes the nonpreemption condition of the RCPSP, thus allowing activities to be interrupted at integer points in time and resumed later without additional penalty cost. The generalized resource-constrained project scheduling (GRCPSP) extends the RCPSP to the case of precedence diagramming type of precedence constraints (minimal finish-start, start-start, start-finish, finish-finish precedence relations), activity ready times, deadlines and variable resource availability's. The resource-constrained project scheduling problem with generalized precedence relations (RCPSP-GPR) allows for start-start, finish-start and finish-finish constraints with minimal and maximal time lags. The MAX-NPV problem aims at scheduling project activities in order to maximize the net present value of the project in the absence of resource constraints. The resource-constrained project scheduling problem with discounted cash flows (RCPSP-DC) aims at the same non-regular objective in the presence of resource constraints. The resource availability cost problem (RACP) aims at determining the cheapest resource availability amounts for which a feasible solution exists that does not violate the project deadline. In the discrete time/cost trade-off problem (DTCTP) the duration of an activity is a discrete, non-increasing function of the amount of a single nonrenewable resource committed to it. In the discrete time/resource trade-off problem (DTRTP) the duration of an activity is a discrete, non-increasing function of the amount of a single renewable resource. Each activity must then be scheduled in one of its possible execution modes. In addition to time/resource trade-offs, the multi-mode project scheduling problem (MRCPSP) allows for resource/resource trade-offs and constraints on renewable, nonrenewable and doubly-constrained resources. We report on recent computational results and end with overall conclusions and suggestions for future research.Scheduling; Optimal;

    The Single Supervisory Mechanism - Panacea or Quack Banking Regulation? : preliminary assessment of the evolving regime for the prudential supervision of banks with ECB involvement : [Version: 16 August 2013]

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    This paper analyzes the evolving architecture for the prudential supervision of banks in the euro area. It is primarily concerned with the likely effectiveness of the SSM as a regime that intends to bolster financial stability in the steady state. By using insights from the political economy of bureaucracy it finds that the SSM is overly focused on sharp tools to discipline captured national supervisors and thus underincentives their top-level personnel to voluntarily contribute to rigid supervision. The success of the SSM in this regard will hinge on establishing a common supervisory culture that provides positive incentives for national supervisors. In this regard, the internal decision making structure of the ECB in supervisory matters provides some integrative elements. Yet, the complex procedures also impede swift decision making and do not solve the problem adequately. Ultimately, a careful design and animation of the ECB-defined supervisory framework and the development of inter-agency career opportunities will be critical. The ECB will become a de facto standard setter that competes with the EBA. A likely standoff in the EBA’s Board of Supervisors will lead to a growing gap in regulatory integration between SSM-participants and other EU Member States. Joining the SSM as a non-euro area Member State is unattractive because the current legal framework grants no voting rights in the ECB’s ultimate decision making body. It also does not supply a credible commitment opportunity for Member States who seek to bond to high quality supervision

    The Single Supervisory Mechanism – Panacea or Quack Banking Regulation? : Preliminary assessments of the evolving regime for the prudential supervision of banks with the ECB involvement (August 16, 2013)

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    This paper analyzes the evolving architecture for the prudential supervision of banks in the euro area. It is primarily concerned with the likely effectiveness of the SSM as a regime that intends to bolster financial stability in the steady state. By using insights from the political economy of bureaucracy it finds that the SSM is overly focused on sharp tools to discipline captured national supervisors and thus under-incentives their top-level personnel to voluntarily contribute to rigid supervision. The success of the SSM in this regard will hinge on establishing a common supervisory culture that provides positive incentives for national supervisors. In this regard, the internal decision making structure of the ECB in supervisory matters provides some integrative elements. Yet, the complex procedures also impede swift decision making and do not solve the problem adequately. Ultimately, a careful design and animation of the ECB-defined supervisory framework and the development of inter-agency career opportunities will be critical. The ECB will become a de facto standard setter that competes with the EBA. A likely standoff in the EBA’s Board of Supervisors will lead to a growing gap in regulatory integration between SSM-participants and other EU Member States. Joining the SSM as a non-euro area Member State is unattractive because the cur-rent legal framework grants no voting rights in the ECB’s ultimate decision making body. It also does not supply a credible commitment opportunity for Member States who seek to bond to high quality supervision

    Research Trends and Outlooks in Assembly Line Balancing Problems

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    This paper presents the findings from the survey of articles published on the assembly line balancing problems (ALBPs) during 2014-2018. Before proceeding a comprehensive literature review, the ineffectiveness of the previous ALBP classification structures is discussed and a new classification scheme based on the layout configurations of assembly lines is subsequently proposed. The research trend in each layout of assembly lines is highlighted through the graphical presentations. The challenges in the ALBPs are also pinpointed as a technical guideline for future research works

    Competition Policy in Switzerland

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    This paper provides a critical review of competition policy in Switzerland. We analyse the legal statute, the institutional arrangements for its implementation and the case law since 1985.competition policy, Switzerland; political economy

    Trans-European-networks and the development of transport in the Eastern Baltic Sea region

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    The European Unions?s task of providing Trans-European Networks (TENs) in transportation, communications and energy transmission which has been enacted by the treaty of Maastricht, is not confined to internal networks in the EU. Since 1994 this task has been widened so as to give support to the economies in transition (EIT) in Central and Eastern Europe that have applied for EU membership. The purpose of this paper is to evaluate the relative importance of the various measures taken in the course of the TEN initiative in the field of transport for economic development of the EIT on the Eastern shore of the Baltic Sea. These actions are taking place in a variety of different fields. Transport infrastracuture upgrading is initiated both in general and with respect to specific links between the EU and the EIT. Apparently, the Baltic Rim EIT ? as all former CMEA members ? suffered and still suffer from the legacy of the socialist past insofar as road, rail and air traffic infrastructure facilities are underdeveloped, in large parts worn-out, or do not comply with quality standards which are necessary for easy accessibility. This has been acknowledged both by the Baltic Rim EIT and by the international community which is supporting network upgrading in all Baltic Rim EIT. Specific infrastructure measures refer to the Pan-European ?Crete Corridors?, i.e. the links between EU members and associated EIT (such as the Via Baltica motorway project), which serve as guiding scheme for EU accession support for EIT in transport infrastructure construction. Other ?hardware? measures are related to the construction of border stations to allow for rapid operational co- operation or customs clearance procedures. In addition, the EU is promoting telematics in the whole Baltic Sea Region in order to facilitate freight traffic. On the ?software? side, TEN initiatives have been enacted to harmonize infrastructure cross-border planning, in particular for Crete Corridors? supervising committees, to account for network externalities. If one widens the narrow definition of infrastructure to institutions, the adjustment of transport regulatory systems of would-be entrants among the EITs to EU regulations and competition policy can also be subsumed under the heading of TENs. The paper will consider these actual approaches of European transport policy as well as the needs of the EIT. Though missing infrastructure links and insufficient capacities are more visible, it turns out that ?software? problems (both from the sphere of regulatory regimes and from administrative procedures) seem to be the most pressing obstacles to transport and trade on the Baltic Rim. The paper will discuss the pros and cons of the various TEN components in transport from the perspective of fiscal federalism and of regional development aid for the EIT. Furthermore it will refer to issues of modal split, in particular with respect to Russia (for which the Baltic Rim is an important transit point), and to intermodal competition between land transport and the Baltic sea lane.

    Evolving CNN-LSTM Models for Time Series Prediction Using Enhanced Grey Wolf Optimizer

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    In this research, we propose an enhanced Grey Wolf Optimizer (GWO) for designing the evolving Convolutional Neural Network-Long Short-Term Memory (CNN-LSTM) networks for time series analysis. To overcome the probability of stagnation at local optima and a slow convergence rate of the classical GWO algorithm, the newly proposed variant incorporates four distinctive search mechanisms. They comprise a nonlinear exploration scheme for dynamic search territory adjustment, a chaotic leadership dispatching strategy among the dominant wolves, a rectified spiral local exploitation action, as well as probability distribution-based leader enhancement. The evolving CNN-LSTM models are subsequently devised using the proposed GWO variant, where the network topology and learning hyperparameters are optimized for time series prediction and classification tasks. Evaluated using a number of benchmark problems, the proposed GWO-optimized CNN-LSTM models produce statistically significant results over those from several classical search methods and advanced GWO and Particle Swarm Optimization variants. Comparing with the baseline methods, the CNN-LSTM networks devised by the proposed GWO variant offer better representational capacities to not only capture the vital feature interactions, but also encapsulate the sophisticated dependencies in complex temporal contexts for undertaking time-series tasks
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