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Lower bound shakedown analysis by using the element free Galerkin method and non-linear programming

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2008年第45-48期197卷 3911-3921页

作者： Chen, Shenshen Liu, Yinghua Cen, Zhangzhi Tsinghua Univ Dept Engn Mech Beijing 100084 Peoples R China

Shakedown analysis is a powerful tool for assessing the safety of structures under variable repeated loads. By using the element free Galerkin (EFG) method and non-linear programming, a novel numerical solution procedure is developed to perform lower bound shakedown analysis of structures made up of elastoperfectly plastic material. The numerical implementation is very simple and convenient because it is only necessary to construct an array of nodes in the domain under consideration. The reduced-basis technique is adopted here to solve the mathematical programming iteratively in a sequence of reduced self-equilibrium stress subspaces with very low dimensions. The self-equilibrium stress field is expressed by linear combination of several self-equilibrium stress basis vectors with parameters to be determined. These self-equilibrium stress basis vectors are generated by performing an equilibrium iteration procedure during elasto-plastic incremental analysis. The Complex method is used to solve the non-linear programming and determine the lower bound of shakedown load. The proposed numerical method is verified by using several numerical examples and the results show good agreement with other available solutions. (C) 2008 Elsevier B.V. All rights reserved.

关键词： shakedown analysis EFG method self-equilibrium stress reduced-basis technique non-linear programming

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COLLISION AVOIDANCE IN COMMERCIAL AIRCRAFT FREE FLIGHT VIA NEURAL NETWORKS AND non-linear programming

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INTERNATIONAL JOURNAL OF NEURAL SYSTEMS 2008年第5期18卷 371-387页

作者： Christodoulou, Manolis A. Kontogeorgou, Chrysa Tech Univ Crete Dept Elect & Comp Engn Khania 73100 Crete Greece

In recent years there has been a great effort to convert the existing Air Traffic Control system into a novel system known as Free Flight. Free Flight is based on the concept that increasing international airspace capacity will grant more freedom to individual pilots during the enroute flight phase, thereby giving them the opportunity to alter flight paths in real time. Under the current system, pilots must request, then receive permission from air traffic controllers to alter flight paths. Understandably the new system allows pilots to gain the upper hand in air traffic. At the same time, however, this freedom increase pilot responsibility. Pilots face a new challenge in avoiding the traffic shares congested air space. In order to ensure safety, an accurate system, able to predict and prevent conflict among aircraft is essential. There are certain flight maneuvers that exist in order to prevent flight disturbances or collision and these are graded in the following categories: vertical, lateral and airspeed. This work focuses on airspeed maneuvers and tries to introduce a new idea for the control of Free Flight, in three dimensions, using neural networks trained with examples prepared through non-linear programming.

关键词： Free Flight neural networks non-linear programming

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Parametric Optimization of Steel Shell Towers of High-Power Wind Turbines

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Procedia Engineering 2013年 57卷 895-905页

作者： Anatoly Perelmuter Vitalina Yurchenko SCAD Soft Ltd 3a Osvity str. 03037 Kyiv Kyiv National University of Civil Engineering and Architecture 31 Povitroflotskyj av. 03680 Kyiv

This paper presents a parametric optimization task of steel conic shell towers of wind-powered generators. The minimum weight of the steel tower has been considered as purpose function when produced capacity of the wind-powered generators has been fixed at the target level. The tower's height, diameters of the middle surface of the tower's conic shell at the base level and at a height if the wind turbine installation, thicknesses of the tower's conic shell, and also the diameter of the wind wheel were considered as design variables. The wind loads applied on steel shell tower have been presented in dependence of design variables and considered as state variables. The optimization problem formulated as non-linear programming task has been solved by improved gradient method. Optimum design decisions of the steel conic shell towers for the wind-powered generators with produced capacity of wide range have been defined. An optimum tower's height and weight in dependence of produced capacity of wind-powered generators have been plotted.

关键词： wind-powered generator steel shell tower parametric optimization non-linear programming gradient method software

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A non-linear programming Model for Funds Allocation in Software Development Projects

A Non-Linear Programming Model for Funds Allocation in Softw...

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4th International Conference on Wireless Communications, Networking and Mobile Computing

作者： Wang, Ning Wang, Lu Yang, Nannan Beijing Univ Posts & Telecommun Econ & Management Sch Beijing 100088 Peoples R China Beijing Univ Technol Coll Econ & Management Beijing Peoples R China Beijing Inst Fashion Technol Business Sch Beijing Peoples R China

ISBN: (纸本)9781424421077

In order to effectively avoid risks that might result in loss of failure in software development process, based on the experiences of software development and project management, this paper identifies 4 potential risk factors specific to software development projects which are integrated with 6 stages in software development process, and proposes a non-linear programming model to optimize funds allocation to reduce the risks. The paper provides an example to validate the effectiveness of the model.

关键词： software project development risk factors funds allocation non-linear programming K-T Condition

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Power-aware scheduling of preemptable jobs on identical parallel processors to meet deadlines

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EUROPEAN JOURNAL OF OPERATIONAL RESEARCH 2012年第1期218卷 68-75页

作者： Rozycki, R. Weglarz, J. Poznan Univ Tech Inst Comp Sci PL-60965 Poznan Poland

This paper deals with a power-aware scheduling of preemptable independent jobs on identical parallel processors where ready time for each job is given and its completion time has to meet a given deadline. Jobs are described by (different) continuous, strictly concave functions relating their processing speeds at a time to the amount of power allotted at the moment. Power is a continuous, doubly constrained resource, i.e. both: its availability at each time instant and consumption over scheduling horizon are constrained. A methodology based on properties of minimum-length schedules is utilized to determine the existence of a feasible schedule for given amounts of energy and power. The question about minimum levels of power and energy ensuring the existence of a feasible schedule for a given set of jobs is also studied. (C) 2011 Elsevier B.V. All rights reserved.

关键词： Power-aware computing Preemptable jobs Ready times Deadlines non-linear programming

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The economic value of improved agrometeorological information to irrigators amid climate variability

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INTERNATIONAL JOURNAL OF CLIMATOLOGY 2012年第4期32卷 567-581页

作者： Mushtaq, Shahbaz Chen, Charlie Hafeez, Mohsin Maroulis, Jerry Gabriel, Hamza Univ So Queensland Australian Ctr Sustainable Catchments Toowoomba Qld 4350 Australia Charles Sturt Univ Int Ctr Water Food Secur Wagga Wagga NSW 2678 Australia CSIRO Black Mt CSIRO Canberra ACT Australia

In Australia, climate variability and the predicted impact of climate change help in making seasonal rainfall less predictable and seasonal irrigation supplies more uncertain, eroding agricultural production prospects and profitability. Water allocation forecasts have economic value to irrigators for making informed cropping decisions. This study estimated the economic value of improved irrigation allocation forecasts in the Coleambally irrigation area (CIA) in southeastern Australia using a non-linear programming model. The model uses production and profit functions to estimate yield and gross margins for various water allocation levels rather than using given crop yields and gross margins. The model also captures the tactical response of improved cropping decisions made by irrigators based on water allocation announcements throughout the irrigation season. Tactical responses include changing the winter crop combinations, abandoning irrigation for a percentage of the summer crops, temporary purchase or sale of water, and deficit irrigation. The estimated economic benefit of improved seasonal water allocation forecasts to the CIA irrigators ranges from AU$1.33 ha(-1) to AU$9.58 ha(-1) (AU$1 = US$0.77). The economic analysis of water allocation forecasts shows that the potential total gross margin for the irrigators at the 100% allocation level was AU$47.6 m, assuming accurate forecast of the end-of-season allocations. A more realistic scenario generates a forecast value of AU$8.9 million reduction in the gross margin (pessimistic water allocation outlook) and AU$1.60 million in the forgone gross margin (optimistic water allocation outlook) for only 5% variation in outlook above or below the actual allocation level of 60%. This suggests that losses far exceed when water allocations are over-estimated by irrigators, as resources and inputs could be overly committed to execute the less-informed cropping plans. The knowledge benefits from forecasts are far greater at th

关键词： water allocation water policy forecasting economic value non-linear programming Australia

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Design optimization with chaos embedded great deluge algorithm

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APPLIED SOFT COMPUTING 2012年第3期12卷 1055-1067页

作者： Baykasoglu, Adil Dokuz Eylul Univ Fac Engn Dept Ind Engn TR-35160 Izmir Turkey

In this paper, the great deluge algorithm (GDA), which has not been previously used in constrained mechanical design optimization problems is employed to solve several design optimization problems selected from the literature. The GDA algorithm needs only one basic parameter to setup, which makes it very attractive for solving optimization problems. First time in this paper, an attempt is made to see whether it is possible to enhance the performance of a very simple algorithm like GDA to solve complex constrained non-linear design optimization problems by embedding chaotic maps in its neighborhood generation mechanism. Eight different chaotic maps are tested and compared in this paper. It is observed that chaotic maps can considerably improve the performance of GDA and enables it to find the best possible solutions for the studied problems. (C) 2011 Elsevier B.V. All rights reserved.

关键词： Great deluge algorithm Chaotic maps Design optimization non-linear programming

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A breakpoint search approach for convex resource allocation problems with bounded variables

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OPTIMIZATION LETTERS 2012年第4期6卷 629-640页

作者： De Waegenaere, Anja Wielhouwer, Jacco L. Tilburg Univ Ctr Econ Res NL-5000 LE Tilburg Netherlands Tilburg Univ Dept Econometr & Operat Res NL-5000 LE Tilburg Netherlands Vrije Univ Amsterdam Dept Accounting Fac Econ NL-1081 HV Amsterdam Netherlands

We present an efficient approach to solve resource allocation problems with a single resource, a convex separable objective function, a convex separable resource-usage constraint, and variables that are bounded below and above. Through a combination of function evaluations and median searches, information on whether or not the upper- and lowerbounds are binding is obtained. Once this information is available for all upper and lower bounds, it remains to determine the optimum of a smaller problem with unbounded variables. This can be done through a multiplier search procedure. The information gathered allows for alternative approaches for the multiplier search which can reduce the complexity of this procedure.

关键词： Resource allocation Multiplier search non-linear programming Pegging

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Energy-efficient spectrum sensing by optimal periodic scheduling in cognitive radio networks

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IET COMMUNICATIONS 2012年第6期6卷 676-684页

作者： Deng, R. He, S. Chen, J. Jia, J. Zhuang, W. Sun, Y. Zhejiang Univ State Key Lab Ind Control Technol Hangzhou 310027 Zhejiang Peoples R China Univ Waterloo Dept Elect & Comp Engn Waterloo ON N2L 3G1 Canada

Nowadays, with the dramatically increased penetration of wireless access, the conflict between spectrum scarcity and under-utilisation is becoming more and more aggravating. A promising technology to tackle such challenge is cognitive radio, of which spectrum sensing is one of the most important functionalities. In this study, the authors consider an essential problem of energy-efficient spectrum sensing in cognitive radio networks. Although most existing works of spectrum sensing mainly focus on determining an optimal sensing time to maximise the detection probability and/or to minimise the false alarm probability, our problem of how to schedule the power-constrained sensor is much more challenging, because of the trade-off among interests of the primary user, secondary user and sensor. The authors formulate it as a non-linear optimisation problem to maximise the sensor lifetime, with necessary constraints of quality and delay of spectrum sensing, and throughput for performance guarantee of primary and secondary users. Moreover, the authors incorporate the distribution information of channel occupancy/vacancy durations into the problem to yield a desirable solution. They propose a novel framework to obtain the optimal energy-efficient periodic scheduling by adopting both non-linear programming and linear programming. Extensive simulation results are provided to validate our theoretical analysis.

关键词： Radio access systems energy-efficient spectrum sensing non-linear programming false alarm probability radio access networks optimal periodic scheduling primary users power-constrained sensor radio spectrum management cognitive radio energy-efficient periodic scheduling cognitive radio networks non-linear optimisation problem wireless access scheduling secondary users

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A generalized compensation theory for active filters based on mathematical optimization in ABC frame

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ELECTRIC POWER SYSTEMS RESEARCH 2012年 90卷 1-10页

作者： Garces, Alejandro Molinas, Marta Rodriguez, Pedro Norwegian Univ Sci & Technol N-7034 Trondheim Norway Univ Tecnol Pereira La Julita Pereira Colombia Univ Politecn Cataluna Terrassa 08222 Spain

This paper presents a generalization of the ABC compensation theory based on mathematical optimization which integrates the neutral losses into the optimization model. The classical ABC theory is shown to be a particular case of the presented generalized compensation approach. The main contribution of this paper is the generalization of the ABC theory considering conflictive objectives which include among them the minimization of the network losses. The work presented here takes. into account not only conventional balanced and pure sinusoidal voltage source but also unbalances and harmonic distortions on the voltage. Four different compensation objectives are studied: invariant instantaneous power, constant power, unity power factor, and pure sinusoidal current. Through these four cases, the flexibility and simplicity of implementation of this approach is demonstrated. In addition, the proposed compensation strategy optimizes the line currents and therefore minimizes the network losses. The main contributions A simulation study which considers the switching effect, the control of the DC link and the size of the shunt compensator is presented. Experimental tests are carried out to verify the theory. (C) 2012 Elsevier B.V. All rights reserved.

关键词： Reactive power compensation ABC theory Optimization non-linear programming Lagrange multipliers Active filters

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