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Optimal re-dispatch of an isolated system considering transient stability constraints

INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS 2013年第1期44卷 728-735页

作者： Calle, Ignacio A. Castronuovo, Edgardo D. Ledesma, Pablo Univ Carlos III Madrid Dept Elect Engn Leganes 28911 Madrid Spain

In this paper, an algorithm for calculating the optimal operation of a system with different load states and fault clearing times is proposed. The algorithm simultaneously considers both economic and stability constraints. The proposed formulation is evaluated on the Majorca and Minorca islands power system, which is a small, isolated system with low inertia. A conventional optimisation tool is used to solve the optimisation problem. The results show the efficiency of the proposed approach and the advantages of including stability restrictions in the optimisation analysis. The application of the algorithm to different operation points is used to evaluate the cost of assuring the transient stability after a severe fault in the transmission grid. The analysis of different fault clearing times is used to estimate the economic savings of implementing a faster protection system. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： Nonlinear programming optimisation algorithms Power system transient stability Optimal power flow with dynamical constraints Stability of power systems

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Learning regular expressions to template-based FAQ retrieval systems

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KNOWLEDGE-BASED SYSTEMS 2013年 53卷 108-128页

作者： Moreo, A. Eisman, E. M. Castro, J. L. Zurita, J. M. Univ Granada Dep Comp Sci & Artificial Intelligence E-18071 Granada Spain

Template-based approaches have proven to be one of the most efficient and robustest ways of addressing Question Answering problems. Templates embody the expert's knowledge on the domain and his/her ability to understand and answer questions, but designing these templates may become a complex task since it is usually carried out manually. Although these methods are not automatic, companies may prefer to undertake this solution in order to offer a better service. In this article, we propose a semiautomatic method to reduce the problem of creating templates to that of validate, and possibly modify, a list of proposed templates. In this way, a better trade-off between reliability the system is still monitored by an expert and cost is achieved. In addition, updating templates after domain changes becomes easier, human mistakes are reduced, and portability is increased. Our proposal is based on inferring regular expressions that induce the language conveyed by a set of previously collected query reformulations. The main contribution of this work consists of the definition of a suitable optimisation measure that effectively reflects some important aspects of the problem and the theoretical soundness that supports it. (C) 2013 Elsevier B.V. All rights reserved.

关键词： Learning regular expressions Template-based QA FAQ retrieval optimisation algorithms Cost reduction

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Matrix-Based Analytical Methods for Recasting Jacobian Models to Power-Law Models 8

Matrix-Based Analytical Methods for Recasting Jacobian Model...

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8th EUROSIM Congress on Modelling and Simulation (EUROSIM)

作者： Idowu, Michael A. Bown, James L. Univ Abertay Sch Contemporary Sci SIMBIOS Ctr Dundee Scotland Univ Abertay Inst Arts Media & Comp Games SIMBIOS Ctr Dundee Scotland

ISBN: (纸本)9780769550732

New methods for inferring data-consistent, self-reconfigurable power-law models from time series data are required and developed. These novel methods may be categorised into two broad groups, namely: straightforward (or direct) inference methods based on power-law models;and a jacobian based indirect inference method. The direct method involves applying direct means to infer a power-law model from time series data. The indirect method, however, uses a new system identification method to first infer a jacobian model as instant and temporal solution to the inverse problem before recasting the inferred jacobian model to corresponding power-law model using our newly developed recast technique. The recast method, in addition to normal behaviour, also provides a novel analytical technique for integrating power-law and jacobian models together. The modelling approach we have developed extends previous work on matrix-based network inference to model interoperability and multiple model transformation in terms of finding two distinct models (solutions) to an inverse problem.

关键词： mathematical modelling simulation reverse engineering optimisation algorithms network inference inverse problems analytical methods matrix algebra and calculus time series analysis system identification parameter estimation methods

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Modelling and mathematical results arising from ferromagnetic problems

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Science China Mathematics 2012年第5期55卷 1053-1067页

作者： DESCLOUX Jean FLUECK Michel RAPPAZ Jacques Department of Mathematics Ecole Polytechnique Fdrale de Lausanne (EPFL)Lausanne 1015Switzerland

Abstract In this article, we investigate the equations of magnetostaties for a configuration where a ferromagnetic material occupies a bounded domain and is surrounded by vacuum. Furthermore, the ferromagnetic law takes the form B=μ0μr（｜H｜）Hi i.e., the magnetizing field H and the magnetic induction B are collinear, but the relative permeability μr is allowed to depend on the modulus of H. We prove the well-posedness of the magnetostatic problem under suitable convexity assumptions, and the convergence of several iterative methods, both for the original problem set in the Beppo-Levi space W1（R3）, and for a finite-dimensional approximation. The theoretical results are illustrated by numerical examples, which capture the known physical phenomena.

关键词： ferromagnetism nonlinear elliptic problems finite element methods optimisation algorithms

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Solving ring loading problems using bio-inspired algorithms

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JOURNAL OF NETWORK AND COMPUTER APPLICATIONS 2011年第2期34卷 668-685页

作者： Bernardino, Anabela Moreira Bernardino, Eugenia Moreira Manuel Sanchez-Perez, Juan Antonio Gomez-Pulido, Juan Angel Vega-Rodriguez, Miguel Polytech Inst Leiria Sch Technol & Management Dept Comp Sci Res Ctr Informat & Commun P-2400 Leiria Portugal Univ Extremadura Polytech Sch Dept Technol Comp & Commun Caceres 10071 Spain

In the last years, several combinatorial optimisation problems have arisen in the communication networks field. In many cases, to solve these problems it is necessary the use of emergent optimisation algorithms. The Weighted Ring Loading Problem (WRLP) is an important optimisation problem in the communication optical network field. When managed properly, the ring networks are uniquely suited to deliver a large amount of bandwidth in a reliable and inexpensive way. An optimal load balancing is very important, as it increases the system's capacity and improves the overall ring performance. The WRLP consists on the design, in a communication network of a transmission route (direct path) for each request, such that high load on the arcs/edges is avoided, where an arc is an edge endowed with a direction. In this paper we study this problem in two different ring types: Synchronous Optical NETworking (SONET) rings and Resilient Packet Ring (RPR). In RPR the purpose is to minimise the maximum load on the ring Arcs (WRALP). In SONET rings the purpose is to minimise the maximum load on the ring Edges (WRELP). The load of an arc is defined as the total weight of those requests that are routed through the arc in its direction and the load of an edge is the total weight of the routes traversing the edge in either direction. In this paper we study both problems without demand splitting and we propose three bio-inspired algorithms: Genetic Algorithm with multiple operators, Hybrid Differential Evolution with a multiple strategy and Hybrid Discrete Particle Swarm optimisation. We also perform comparisons with other algorithms from literature. Simulation results verify the effectiveness of the proposed algorithms. (C) 2010 Elsevier Ltd. All rights reserved.

关键词： Communication networks Bio-inspired algorithms optimisation algorithms Swarm Intelligence Weighted Ring Arc-Loading Problem Weighted Ring Edge-Loading Problem

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Recent advances on key technologies for innovative manufacturing

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JOURNAL OF INTELLIGENT MANUFACTURING 2011年第5期22卷 675-691页

作者： Brousseau, Emmanuel Eldukhri, Eldaw Cardiff Univ Mfg Engn Ctr Cardiff S Glam Wales

Through the I*PROMS Network of Excellence which originated during the sixth Framework Programme of the European Commission, this paper introduces a European vision of the essential research areas to deliver future innovations in manufacturing. In particular, these areas are identified as Advanced Production Machines, Production Automation and Control, Innovative Design Technologies and Production Organisation and Management. Then, special attention is given to the main findings from the authors' research programme since the start of I*PROMS in October 2004 for a number of technologies belonging to these four generic research streams.

关键词： Advanced production machines Micro and nano manufacturing Rapid prototyping Production automation and control optimisation algorithms Innovative design technologies Conceptual design Automatic feature recognition Production organisation and management Fit manufacturing

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ITSE optimal controller design and achievable performance bounds

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INTERNATIONAL JOURNAL OF CONTROL 2009年第11期82卷 2115-2126页

作者： Carrasco, D. S. Salgado, M. E. Univ Tecn Federico Santa Maria Dept Elect Engn Valparaiso Chile

This article proposes a methodology to design optimal controllers and to compute achievable performance bounds in the control of linear, stable discrete-time SISO plants. The performance is measured using a time-weighted cost function (ITSE) of the tracking error for a step reference or a step output disturbance, combined with a measure of the energy of the incremental control. The proposed methodology relies on the use of a function space product that, for stable systems, can be defined in both the frequency and the time-domains. The solution technique requires the expansion of stable functions in orthogonal basis. An analytical expression is found for the computation of the optimal coefficients of the expansion. Numerical examples are included to illustrate the results.

关键词： optimal control performance bounds linear systems optimisation algorithms

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Time-constant control analysis of microwave differentiators

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IET MICROWAVES ANTENNAS & PROPAGATION 2009年第7期3卷 1044-1050页

作者： Tsai, L. -C. Wu, Y. -T. Lunghwa Univ Sci & Technol Dept Elect Engn Tao Yuan 33306 Taiwan

A model describing the time constant of a wide-band microwave differentiator is presented. The time constant combined with the amplitude response dictates the circuit behaviour of a microwave differentiator. By representing the formulations of differentiators in the discrete-time (or Z) domain, the authors implement the differentiators with equal-length transmission lines. The approach method consists of discrete signal processing techniques, transfer functions in the Z domain and optimisation algorithms. Three differentiators with different time constants and frequency bands are built and tested. The experimental results are in good agreement with theoretical values.

关键词： equal-length transmission lines discrete signal processing techniques Microwave circuits and devices circuit behaviour Waveguides and microwave transmission lines Time control amplitude response transfer functions optimisation wide-band microwave differentiator time-constant control analysis discrete-time domain transmission lines Control system analysis and synthesis methods optimisation techniques Z domain algorithms microwave devices optimisation algorithms

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Experimental validation of optimisation strategies in hydroforming of T-shaped tubes

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INTERNATIONAL JOURNAL OF MATERIAL FORMING 2008年第1-Sup期1卷 323-326页

作者： Di Lorenzo, R. Ingarao, G. Gagliardi, F. Filice, L. Univ Palermo Dipartimento Tecnol Meccan Prod & Ingn Gest I-90128 Palermo Italy Univ Calabria Dept Mech Engn I-87036 Arcavacata Di Rende CS Italy

For three dimensional tube hydroforming operations (i.e. T or Y shaped tubes) the calibration of both material feeding history and internal pressure path during the process is crucial and many approaches to such optimization were presented;the authors developed some procedures to optimize pressure paths and punch velocity histories with the application of an integrated method FEM - Gradient based optimization tools. In this paper, an experimental validation campaign of the utilized optimization strategies is presented with the aim to assess the effectiveness of the developed procedures. An optimization procedure (gradient based techniques) was applied on the process parameters leading to the determination of an optimal pressure path. Finally, a testing machine was set up to carry out hydroforming operations on T-shaped tubes. The developed equipment allows a computer assisted control of both the internal fluid pressure paths and the punches actions (material feeding paths). The experimental evidences validated the results obtained by the optimization strategies utilized to design the process parameters.

关键词： Tube hydroforming optimisation algorithms Experimental validation

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Geometry and New and Future Spatial Patterns

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Architectural Design 2009年第6期79卷

作者： Helmut Pottman

Despite architects' preoccupation with designing geometric surfaces, there has remained a gap between design and construction. The realisation of complex architectural freeform shapes and the generation of panel patterns continues to be especially challenging, limited by material and manufacturing constraints. Here, Helmut Pottmann , Head of Geometric Modelling and the Industrial Geometry Group within the Institute of Discrete Mathematics and Geometry at Vienna University of Technology (TU Vienna), explores the possibilities thrown up by new research employing fabrication‐aware design software. Copyright © 2009 John Wiley & Sons, Ltd.

关键词： Alhambra Palace fabrication‐aware design tools freeform shapes texture mapping techniques Designtoproduction Evolute Gehry Technologies optimisation algorithms Geometric Modelling and Industrial Geometry research group at TU Vienna Asymptote Architecture, Yas Island Marina Hotel, Abu Dhabi, 2009 Subdivision Buckminster Fuller geodesic domes freeform quad meshes with planar faces (known as PQ meshes) Frei Otto Lars Spuybroek siliceous microskeletons of radiolaria hexagonal meshes Gaussian curvature non‐convex panels Future Systems (Selfridges department store, Birmingham, 1999), arrangements of circles and spheres ‘circle‐packing’ (CP) meshes unsolved mathematical problems tri‐hex meshes Voronoi diagrams shape evolution algorithms computation of 4‐D patterns flexible space structures Kas Oosterhuis Hyperbody research group

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