Search results for "CONSTRAINT"
showing 10 items of 361 documents
Effectiveness of constraint-induced movement therapy on activity and participation after stroke: a systematic review and meta-analysis of randomized …
2011
Objective: To examine the effect of constraint-induced movement therapy and modified constraint-induced movement therapy on activity and participation of patients with stroke (i.e. the effect of different treatment durations and frequency) by reviewing the results of randomized controlled trials. Data sources: A systematic literature search was conducted in MEDLINE, CINAHL, EMBASE, PEDro, OTSeeker, CENTRAL and by manual search. Review methods: Randomized controlled trials for patients over 18 years old with stroke and published in Finnish, Swedish, English or German were included. Studies were collected up to the first week in May 2011. The evidence was high, moderate, low or no evidence a…
No synergy needed: ecological constraints favor the evolution of eusociality.
2015
In eusocial species, some individuals sacrifice their own reproduction for the benefit of others. It has been argued that the evolution of sterile helpers in eusocial insects requires synergistic efficiency gains through cooperation that are uncommon in cooperatively breeding vertebrates and that this precludes a universal ecological explanation of social systems with alloparental care. In contrast, using a model that incorporates realistic ecological mechanisms of population regulation, we show here that constraints on independent breeding (through nest-site limitation and dispersal mortality) eliminate any need for synergistic efficiency gains: sterile helpers may evolve even if they are …
Employment Protection Reform and Unemployment Inequality in a Matching Model (Reforme De La Protection De L'Emploi Et Inegalites Face Au Chomage Dans…
2007
This paper studies the impact of an unemployment protection legislation reform - a substitution between an experience rated tax and firing costs - on the level and structure of unemployment by skills. In this purpose, we consider a matching model which incorporates endogenous reservation products for job creation and job destruction, labor demand derives from a free entry condition and the tax rate aimed at financing unemployment benefits results from a balanced budget constraint. In this setting, it is shown that the introduction of the experience rated tax may improve the performance of the labor marekt; the drawbacks of such a reform depend on the degree of substitution between tradition…
On Constraint Handling in Surrogate-Assisted Evolutionary Many-Objective Optimization
2016
Surrogate-assisted evolutionary multiobjective optimization algorithms are often used to solve computationally expensive problems. But their efficacy on handling constrained optimization problems having more than three objectives has not been widely studied. Particularly the issue of how feasible and infeasible solutions are handled in generating a data set for training a surrogate has not received much attention. In this paper, we use a recently proposed Kriging-assisted evolutionary algorithm for many-objective optimization and investigate the effect of infeasible solutions on the performance of the surrogates. We assume that constraint functions are computationally inexpensive and consid…
A biased random-key genetic algorithm for the time-invariant berth allocation and quay crane assignment problem
2017
We address Berth Allocation and Quay Crane Assignment Problems in a heuristic wayWe propose a Biased Random-Key Genetic Algorithm for BACAP and its extension BACASPSolutions of the Genetic Algorithm are improved by a Local SearchThe complete procedure obtains high-quality solutions for large instances Maritime transportation plays a crucial role in the international economy. Port container terminals around the world compete to attract more traffic and are forced to offer better quality of service. This entails reducing operating costs and vessel service times. In doing so, one of the most important problems they face is the Berth Allocation and quay Crane Assignment Problem (BACAP). This pr…
On the Computation of the Efficient Frontier of the Portfolio Selection Problem
2012
An easy-to-use procedure is presented for improving theε-constraint method for computing the efficient frontier of the portfolio selection problem endowed with additional cardinality and semicontinuous variable constraints. The proposed method provides not only a numerical plotting of the frontier but also an analytical description of it, including the explicit equations of the arcs of parabola it comprises and the change points between them. This information is useful for performing a sensitivity analysis as well as for providing additional criteria to the investor in order to select an efficient portfolio. Computational results are provided to test the efficiency of the algorithm and to i…
Constraint handling in efficient global optimization
2017
Real-world optimization problems are often subject to several constraints which are expensive to evaluate in terms of cost or time. Although a lot of effort is devoted to make use of surrogate models for expensive optimization tasks, not many strong surrogate-assisted algorithms can address the challenging constrained problems. Efficient Global Optimization (EGO) is a Kriging-based surrogate-assisted algorithm. It was originally proposed to address unconstrained problems and later was modified to solve constrained problems. However, these type of algorithms still suffer from several issues, mainly: (1) early stagnation, (2) problems with multiple active constraints and (3) frequent crashes.…
Fully Polynomial Time Approximation Scheme for the Two-Parallel Capacitated Machines Scheduling Problem Under Unavailability Constraint
2010
Abstract Decision Support Systems (DSS) ensure the computer-based support for the conscientious decision-making in solving problems that require a large amount of information processing and complex scenarios. DSS for Transportation (DSST) are intelligent systems that are used at operational and organizational management levels. Operating a DSST in a public transportation web-based monitoring system is presented in this paper.
A NEW REPRESENTATION OF ENERGY STORAGE SYSTEMS OPERATION USING FOURIER THEORY IN OPTIMAL SMART GRIDS MANAGEMENT
2012
This paper investigates the possibility to use a new modeling of Energy Storage Systems based on zero integral functions. Such functions represent the course of the energy level stored in batteries during the solution of optimal management problems in smart-grids. Storage devices, such as all the other components that are required to meet an integral capacity constraint along the dispatch time, must show the same State of Charge at the start and at the end of the timeframe considered for operation. In this paper, a set of sinusoidal functions have been used for the synthesis of the charge and discharge course of energy Storage Systems. Such representation allows to eliminate the difficult c…
Frequency constrained optimal Power Flow based on Glow-worm Swarm Optimization in Islanded Microgrids
2015
This work presents an application of a swarm optimization method to solve the optimal power flow problem taking into account the constraints of frequency and line ampacity in three-phase islanded Microgrids. Each generation unit is equipped with a Power Electronics Interface. In the considered formulation, the droop control parameters are considered as variables to be adjusted by a higher control level, while the frequency is kept in rated bounds. Another typical constraint for OPF formulation, the max ampacity of each line, is also considered. Two case studies with different dimensions and electrical features have been considered and the obtained results show the efficiency of the proposed…