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Appraisal of water quality indices for service reservoirs in water distribution networks

WATER SCIENCE AND TECHNOLOGY 2020年第8期81卷 1606-1614页

作者： Nyirenda, M. S. Tanyimboh, T. T. Univ Witwatersrand Sch Civil & Environm Engn Johannesburg South Africa GIBB PTY Ltd Woodmead North Off Pk54 Maxwell Dr Woodmead South Africa

The use of water quality indices to aggregate pollution loads in rivers has been widely studied, with researchers using various sub-indices and aggregation methods. These have been used to combine various quality variables at a sampling point in a river into an overall water quality index to compare the state of water quality in different river reaches. Service reservoirs in a water distribution network, like rivers, have complex mixing mechanisms, are subjected to various water quality variables and are variably sized and sited. Water quality indices and the relevant sub-indices are formulated here and applied to service reservoirs within a water distribution network. This is in an attempt to compare holistically the performance of service reservoirs in solutions of optimisation algorithms with regards to water quality.

关键词： optimisation algorithms service reservoirs water distribution networks water quality index

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Evaluation of existing optimal VAr planning tools on utility systems

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IEE PROCEEDINGS-GENERATION TRANSMISSION AND DISTRIBUTION 1998年第6期145卷 663-668页

作者： Vaahedi, E Mansour, Y Li, W Tamby, J Sun, D Maratukolam, D BC Hydro Burnaby BC Canada Empros Siemens Minneapolis MN USA Cegelec ESCA Bellevue WA USA EPRI Palo Alto CA USA

Findings of a recently completed EPRI project conducting a comprehensive evaluation of optimal VAr planning/OPF tools are reported. Three selected tools were adapted to address VAr allocation studies on four large-scale utility systems. The results obtained indicate that the use of such tools offers significant savings in cost of added MVAr requirements and the number of allocated sites with reasonable and manageable computer execution times. Based on the adaptation requirements for the different programs and studies conducted, recommendations on enhancement areas for the selected tools are provided, One of the major concerns in these studies should be the implementability of the results. This requires careful design including assignment of controls and constraints that can be implemented in the field together with the available tools to provide such requirements.

关键词： utility systems load flow Power system planning and layout Power transmission, distribution and supply optimisation algorithms EPRI project reactive power allocation power system planning optimal power flow VAr allocation optimal VAr planning tools reactive power

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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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Combinatorial approaches to heterogeneous catalysis: strategies and perspectives for academic research

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CATALYSIS TODAY 2001年第4期67卷 309-318页

作者： Holzwarth, A Denton, P Zanthoff, H Mirodatos, C Inst Rech Catalyse CNRS F-69626 Villeurbanne France

The application of combinatorial chemistry to heterogeneous catalysis is analysed in terms of current strategies and perspectives on the industrial and academic levels. Potential methodologies for academic research laboratories are proposed with emphasis on both theoretical and practical considerations. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词： heterogeneous catalysis combinatorial chemistry optimisation algorithms

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Joint coding bit-rate and activity rate optimisation in wireless visual sensor networks

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IET COMMUNICATIONS 2020年第19期14卷 3428-3439页

作者： Kafafy, Mai Fahmy, Yasmine Cairo Univ Elect & Commun Engn Dept Giza 12613 Egypt

Optimising the coding bit-rates and activity rates of sensor nodes is essential for the functionality and survival of wireless sensor networks as these rates not only affect the amount of information collected by the network, but also affect its power consumption. This study proposes a framework for joint coding bit-rates and activity rates optimisation (CARO) of sensor nodes in wireless visual sensor networks under limited energy constraints. The framework uses the concept of accumulative visual information (AVI) as a measure of the amount of visual information collected from a sensor node. The authors propose two optimisation algorithms for the following two cases: (I) networks with predetermined operation time, where algorithm CARO I maximises the AVI of the network over its predetermined operation time. (II) Best effort networks, where algorithm CARO II maximises the network operation time under constraints on the collected visual information. Simulations show that optimising the rates using CARO maximises the AVI of the network and extends its operation time compared to the straightforward solution when all nodes have equal activity rates. This is because the authors' framework takes into consideration that different nodes in different locations may operate under different conditions and collect information of different significance.

关键词： wireless sensor networks image sensors optimisation codes equal activity rates visual information algorithm CARO II predetermined operation time optimisation algorithms AVI accumulative visual information activity rates optimisation wireless sensor networks sensor node coding bit-rates wireless visual sensor networks activity rate optimisation joint coding bit-rate

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Joint scheduling of spare parts production and service engineers based on progressive Pareto algorithm

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INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2024年第6期62卷 2124-2141页

作者： Miao, Bingxin Deng, Qianwang Zhang, Like Huo, Zhangwen Han, Weifeng Hunan Univ State Key Lab Adv Design & Mfg Vehicle Body Changsha Peoples R China Zhengzhou Univ Light Ind Henan Prov Key Lab Intelligent Mfg Mech Equipment Zhengzhou Peoples R China China Railway Tunnel Grp Co Ltd Guangzhou Peoples R China Hunan Univ State Key Lab Adv Design & Mfg Vehicle Body 2 South Lushan Rd Changsha 410082 Peoples R China

We analyse the joint scheduling of spare parts production and service engineers in a multi-site maintenance system. In the system, for each failure, a service engineer with the required spare part needs to be allocated for on-site maintenance. If one of the required resources is not readily available, the maintenance task can be satisfied via an external channel with quick responsiveness but high involved costs. Service providers need to make an efficient plan, including production scheduling of spare parts, allocation of service engineers and outsourcing strategy. First, a mathematical model with the objectives of minimum total outsourcing costs and minimum weighted tardiness is formulated. Then, a novel and knowledge-based heuristic algorithm is developed, namely progressive Pareto algorithm based on step-size (PPAS). To verify the performance of PPAS, it is compared against other well-known algorithms, including NSGA-II, MOEA/D, NNIA, RIPG, MMOIG and MNNIA. Finally, the effectiveness of the joint scheduling mode is demonstrated by comparing it with the separate optimisation mode of spare parts production and workforce allocation.

关键词： Maintenance spare parts service engineers joint scheduling optimisation algorithms

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Advantages and disadvantages of thruster allocation procedures in preliminary dynamic positioning predictions

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OCEAN ENGINEERING 2016年 123卷 96-102页

作者： Mauro, Francesco Nabergoj, Radoslav Univ Trieste Dept Engn & Architecture Via Valerio 10 I-34127 Trieste Italy Univ Rijeka Fac Engn Vukovarska 58 Rijeka 51000 Croatia

Minimisation of power consumption is the primary target of the most commonly used procedures and strategies for the capability prediction of DP systems installed on floating objects and, therefore, dealing with an huge amount of limitations or restrictions that should be satisfied at the same time for different operating conditions. However, in the particular case of the "extreme limit prediction" for a considered system, other factors assume a prominent importance instead of fuel consumption, like the ability to use all the available power to keep the position in heavy weather conditions. When the maximum operating cases for a vessel are analysed, other effects like thruster-hull interaction and thruster-thruster interaction are rarely considered. To take into account the above-mentioned effects, different thrust allocation strategies were studied and implemented in a capability prediction suite. In this paper a new allocation philosophy is presented, with the aim of maximising the DP capability of a vessel operating in heavy whether conditions. An application of the procedure on two existing offshore vessels is also considered to highlight the effects of different allocation strategies and of the interaction effects on the resulting DP capability in terms of "operational rosettes". (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Dynamic positioning optimisation algorithms Thrust allocation

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Scenario-based multi-objective optimisation with loadability in islanded microgrids considering load and renewable generation uncertainties

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IET RENEWABLE POWER GENERATION 2019年第5期13卷 785-800页

作者： Jithendranath, J. Das, Debapriya Indian Inst Technol Kharagpur Dept Elect Engn Kharagpur 721302 W Bengal India

Operation of microgrids in islanded mode either by intention or by involuntary action is of increasing concern nowadays. Optimal operation and control of such islanded microgrids considering various objectives are crucial for effective planning problem. This work proposes a new methodology for optimal operation of islanded microgrids considering economic and emission objectives together with loadability in droop-regulated islanded microgrid. Loadability being one of dominant aspects to be considered for effective microgrid planning and operation to ensure increased voltage-stability margin in the entire due course of operation. In conjunction with that islanded microgrid operational constraints and uncertainty in various system parameters need to be considered to interpret real-time operation of the microgrid. In the light of above, a multi-objective optimisation problem in droop-regulated islanded microgrid is formulated with economic-emission-loadability objectives by considering uncertainties in load demand and renewable generation along with system constraints. The formulated problem is solved using multi-objective antlion optimiser algorithm and validated on the test system. The performance of the proposed approach is compared with other optimisation algorithms to show its effectiveness. The importance of considering loadability along with economic-emission objectives to achieve compromised solution resulted in ensuring better operational planning of droop-regulated islanded microgrids.

关键词： optimisation distributed power generation evolutionary computation considering loadability economic-emission objectives operational planning droop-regulated islanded microgrid scenario-based multiobjective optimisation islanded microgrids renewable generation uncertainties islanded mode optimal operation effective planning problem economic emission objectives effective microgrid planning islanded microgrid operational constraints real-time operation multiobjective optimisation problem economic-emission-loadability objectives optimiser algorithm optimisation algorithms

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Euler-based throughflow method for inverse design and optimisation of turbomachinery blades

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PROGRESS IN COMPUTATIONAL FLUID DYNAMICS 2014年第2期14卷 71-82页

作者： Taddei, Simone Rosa Larocca, Francesco Politecn Torino Aerosp Prop Grp Dept Mech & Aerosp Engn I-10129 Turin Italy

An inviscid model for complete axial flow turbomachinery is adopted, which replaces the blades with throughflow surfaces. The main effects of the real blades on the flow are modelled by blade forces. The inverse method predicts the axisymmetric flow field and throughflow surface geometry for a specified distribution of azimuthal inviscid force. This quantity drives the meridional distribution of rotor shaft power. Euler equations are solved by an implicit upwind finite-volume scheme. The time-marching computation includes an evolutionary equation for each throughflow surface, which is solved by implicit finite differences. Standard optimisation algorithms are used to find distributions of azimuthal force that minimise some sample cost functions. The optimal blade shapes are given by the corresponding geometrical solutions of the inverse problem. Since the cost function evaluation is reduced to an inviscid two-dimensional computation, the entire process is significantly less time-consuming than those based on three-dimensional CFD solvers.

关键词： axisymmetric flow field blade force computational fluid dynamics CFD Euler-based throughflow turbomachinery blade inverse design optimisation algorithms throughflow surface

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Current-mode group-delay equalisation using pole-zero mirroring technique

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IEE PROCEEDINGS-CIRCUITS DEVICES AND SYSTEMS 2000年第4期147卷 257-263页

作者： Al-Hashimi, BM Dudek, F Moniri, M Staffordshire Univ Sch Engn & Adv Technol VLSI Signal Proc Grp Beaconside ST18 0AD Staffs England

The authors describe an efficient method for designing current-mode group-delay equalisers, The method is based on introducing zeros into the right-hand s-plane by mirroring the Doles of an LC ladder network. This is achieved by developing a current-mode model capable of implementing the pole-zero mirroring technique. Using multiple-output OTAs and grounded capacitors, the model is used to derive an nth-order active group-delay equaliser structure which is simpler, has better correction accuracy and is less sensitive when compared to cascade approach based equalisers. The equaliser design involves two optimisation algorithms. The first algorithm generates a polynomial function whose group-delay response equalises the filter response. The second algorithm produces the equaliser component values as a result of solving a set of nonlinear equations generated from coefficient matching the equaliser transfer function to the polynomial generated from the first algorithm. Simulated results with CMOS OTAs and measured results based on discrete realisation of a 6th-order equaliser are included. The results demonstrate that the equaliser can effectively compensate the delay characteristics of a 7th-order 5.75MHz lowpass elliptic video filter to < 5 ns ripple over 90% of the filter passband.

关键词： multiple-output OTAs ladder networks optimisation algorithms analogue circuits grounded capacitors LC ladder network operational amplifiers equalisers poles and zeros network synthesis lowpass elliptic video filter group-delay response pole-zero mirroring technique current-mode circuits nonlinear equations equaliser transfer function delay characteristics compensation correction accuracy current-mode model filter response circuit optimisation efficient design method transfer functions coefficient matching current-mode group-delay equalisers 6th-order equaliser CMOS OTAs nth-order active group-delay equaliser structure polynomial function

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