Encontrados 15 documentos, a visualizar página 1 de 2
A Java expression evaluator for nonlinear programming
Matias, João; Correia, Aldina; Serôdio, Carlos; Teixeira, C.; Mestre, PedroFinding the optimal value for a problem is usual in many areas of knowledge where in many cases it is needed to solve Nonlinear Optimization Problems. For some of those problems it is not possible to determine the expression for its objective function and/or its constraints, they are the result of experimental procedures, might be non-smooth, among other reasons. To solve such problems it was implemented an API...
Penalty fuzzy function for derivative-free optimization
Matias, João; Mestre, Pedro; Correia, Aldina; Couto, Pedro; Serôdio, Carlos; Melo-Pinto, P.Penalty and Barrier methods are normally used to solve Nonlinear Optimization Problems constrained problems. The problems appear in areas such as engineering and are often characterised by the fact that involved functions (objective and constraints) are non-smooth and/or their derivatives are not know. This means that optimization methods based on derivatives cannot net used. A Java based API was implemented, i...
Indoor location using fingerprinting and fuzzy logic
Mestre, Pedro; Coutinho, Luis; Reigoto, Luis; Matias, João; Correia, Aldina; Couto, Pedro; Serôdio, CarlosIndoor location systems cannot rely on technologies such as GPS (Global Positioning System) to determine the position of a mobile terminal, because its signals are blocked by obstacles such as walls, ceilings, roofs, etc. In such environments. The use of alternative techniques, such as the use of wireless networks, should be considered. The location estimation is made by measuring and analysing one of the param...
A lightweight indoor localization model based on motley-keenan and COST
Serôdio, Carlos; Coutinho, Luis; Reigoto, Luis; Matias, João; Correia, Aldina; Mestre, PedroThis paper presents a novel approach to WLAN propagation models for use in indoor localization. The major goal of this work is to eliminate the need for in situ data collection to generate the Fingerprinting map, instead, it is generated by using analytical propagation models such as: COST Multi-Wall, COST 231 average wall and Motley- Keenan. As Location Estimation Algorithms kNN (K-Nearest Neighbour) and WkNN ...
RSS and LEA adaptation for indoor location using fingerprinting
Mestre, Pedro; Reigoto, Luis; Coutinho, Luis; Correia, Aldina; Matias, João; Serôdio, CarlosFingerprinting is an indoor location technique, based on wireless networks, where data stored during the offline phase is compared with data collected by the mobile device during the online phase. In most of the real-life scenarios, the mobile node used throughout the offline phase is different from the mobile nodes that will be used during the online phase. This means that there might be very significant diffe...
Improvement of a filters method in a derivative free optimization
Matias, João; Mestre, Pedro; Correia, Aldina; Serôdio, CarlosConstraints nonlinear optimization problems can be solved using penalty or barrier functions. This strategy, based on solving the problems without constraints obtained from the original problem, have shown to be e ective, particularly when used with direct search methods. An alternative to solve the previous problems is the lters method. The lters method introduced by Fletcher and Ley er in 2002, , has been w...
Filters method in direct search optimization, new measures to admissibility
Correia, Aldina; Matias, João; Mestre, Pedro; Serôdio, CarlosConstrained nonlinear optimization problems are usually solved using penalty or barrier methods combined with unconstrained optimization methods. Another alternative used to solve constrained nonlinear optimization problems is the lters method. Filters method, introduced by Fletcher and Ley er in 2002, have been widely used in several areas of constrained nonlinear optimization. These methods treat optimizatio...
A web-based tool to evaluate the iterative processes of direct search methods
Mestre, Pedro; Correia, Aldina; Matias, João; Teixeira, Christophe; Almeida, José; Serôdio, CarlosConstrained and unconstrained Nonlinear Optimization Problems often appear in many engineering areas. In some of these cases it is not possible to use derivative based optimization methods because the objective function is not known or it is too complex or the objective function is non-smooth. In these cases derivative based methods cannot be used and Direct Search Methods might be the most suitable optimizatio...
Classification of some penalty methods
Correia, Aldina; Matias, João; Mestre, Pedro; Serôdio, CarlosOptimization problems arise in science, engineering, economy, etc. and we need to find the best solutions for each reality. The methods used to solve these problems depend on several factors, including the amount and type of accessible information, the available algorithms for solving them, and, obviously, the intrinsic characteristics of the problem. There are many kinds of optimization problems and, consequen...
Direct search optimization application programming interface with remote access
Mestre, Pedro; Matias, João; Correia, Aldina; Serôdio, CarlosSearch Optimization methods are needed to solve optimization problems where the objective function and/or constraints functions might be non differentiable, non convex or might not be possible to determine its analytical expressions either due to its complexity or its cost (monetary, computational, time,...). Many optimization problems in engineering and other fields have these characteristics, because function...
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