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Applications of adaptive stiffness suspensions to vibration control of a high-speed stiff rotor with tilting pad bearings

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ARCHIVE OF APPLIED MECHANICS 2021年第4期91卷 1819-1835页

作者： Abbasi, A. Khadem, S. E. Bab, Saeed Tarbiat Modares Univ Dept Mech Engn POB 14115-177 Tehran Iran Niroo Res Inst Mech Rotary Equipment Dept POB 14665-517 Tehran Iran

The current paper discusses the optimum parameter setting of asymmetric high-static low-dynamic stiffness (HSLDS) suspensions to reduce vibrations of a high-speed symmetric rotary system, excited by an unbalance force. The rotating system consists of a shaft that is supported by tilting pad journal bearings on the asymmetric HSLDS suspensions. The Reynolds equation is solved numerically to obtain the oil pressure distribution for each pad of bearing. With the aim of calculating the hydrodynamic forces applied to each pad, an analytical approach is presented. Its results are validated using a numerical integration approach. Given the considerable difference between the shaft mass and pads moment of inertia, the mathematical equations governing the motions of disk, journal, bearing and pads are solved implementing a routine specified for stiff ordinary differential equations in MATLAB. The optimum parameters of HSLDS suspensions are obtained, using a multi-objective genetic algorithm. Design objectives are considered to minimize the vibrations of rotor, journal, and bearing and bearing force transmission to the external supports. The efficiency of optimum HSLDS suspensions in reducing the vibrations of journal, bearing and rotor within the operating speed range is shown. The high performance of the designed suspensions in decreasing the bearings force transmission is proved as well. In addition, the design robustness to uncertainties in HSLDS suspensions parameters is studied.

关键词： High-static low-dynamic stiffness Suspension Rotor Journal Tilting pad journal bearing multi-objective genetic algorithm

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Determination of interfacial heat transfer coefficients in a sand mould casting process using an optimised inverse analysis

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APPLIED THERMAL ENGINEERING 2015年 78卷 682-694页

作者： Palumbo, Gianfranco Piglionico, Vito Piccininni, Antonio Guglielmi, Pasquale Sorgente, Donato Tricarico, Luigi Politecn Bari DMMM Bari Italy

Determination of the interface heat transfer coefficients in casting processes represents a fundamental step in the creation of a reliable numerical model that can predict some of the most common defects (for example hot tear or residual stress) which may affect the process. This work focuses on the most appropriate methodology to determine the heat transfer coefficients for the numerical modelling of the casting process of a super duplex stainless steel (ASTM A890 Gr. 5A) using a silica sand mould. Experimental instrumented castings were used to acquire (both in the casting and in the sand) temperature changes for a number of points of interest by means of thermocouples;in addition, the entire process was simulated using the finite difference method commercial software package MAGMASOFT((R)) (v. 5.2) in order to calculate the temperature at the same points at any step of the process. Firstly, the most influential input parameters were chosen in order to determine the factors to be investigated using a reduced factorial scheme. Further simulations, in which the value of the chosen factors was changed, made it possible to create response surfaces using as a response variable the value of the mismatch between the experimental and numerical temperature changes in the same points. Finally, the optimisation procedure using a multi-objective genetic algorithm was performed, with the goal of finding optimal values for the input parameters, i.e. those with which the mismatch between experimental and numerical temperature changes is minimised. As confirmed by the numerical simulations using the results of the optimisation procedure, the methodology proposed enabled us to determine the correct values of the input variables for modelling the casting process of the ASTM A890 Gr. 5A. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Super duplex stainless steel (ASTM A890 Gr. 5A) Casting MAGMASoft Interface heat transfer coefficients Response surface multi-objective genetic algorithm

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Theoretical analysis and design optimization of wideband input/output branch waveguide couplers for a sheet beam traveling wave tube

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JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS 2015年第15期29卷 2002-2013页

作者： Shu, G. X. Wang, J. X. Liu, G. Zheng, Y. Yang, L. Y. Luo, Y. Univ Elect Sci & Technol China Sch Phys Elect Chengdu 610054 Peoples R China Univ Calif Davis Dept Appl Sci Davis CA 95616 USA

The branch waveguide coupler (BWC) with an intrinsically excellent microwave property in an extremely wide frequency range was proposed to build the input/output (I/O) structure for the sheet beam traveling wave tube. The odd and even mode theory is utilized to analyze the BWC. Based on the theory, a code is written to calculate its microwave performance parameters. The numerical calculation has a good agreement with the computation simulation. To improve the efficiency of developing the BWC, a novel design optimization approach based on the MATLAB optimization tool is proposed. A BWC with nine branch waveguides is optimized using multi-objective genetic algorithm. In addition to the excellent microwave property, a compact configuration is achieved. It is predicted that the I/O structure possesses a very good performance with coupling above -0.3dB, port reflectivity under -19dB, and isolation less than -15dB in a broad frequency range of 37.4-51.0GHz, corresponding to a bandwidth of 13.6GHz (30.7%).

关键词： sheet beam traveling wave tubes input output structure multi-objective genetic algorithm odd and even mode theory branch waveguide coupler wideband coupler

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A multi-objective particle swarm optimization for project selection problem

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EXPERT SYSTEMS WITH APPLICATIONS 2010年第1期37卷 315-321页

作者： Rabbani, M. Bajestani, M. Aramoon Khoshkhou, G. Baharian Univ Tehran Dept Ind Engn Tehran 4563 Iran

Selecting the most appropriate projects out of a given set of investment proposals is recognized as a critical issue for which the decision maker takes several aspects into consideration. Since many of these aspects may be conflicting, the problem is rendered as a multi-objective one. Consequently, we consider a multi-objective project selection problem in this Study where total benefits are to be maximized while total risk and total coat must be minimized, simultaneously. Since solving an NP-hard problem becomes demanding as the number of projects grows, a multi-objective particle swarm with new selection regimes for global best and personal best for swarm members is designed to find the locally Pareto-optimal frontier and is compared with a salient multi-objective genetic algorithm, i.e. SPEAII, based on some comparison metrics with random instances. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： multi-objective particle swarm Project selection problem multi-objective genetic algorithm

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Effective semicontinuous distillation design for separating normal alkanes via multi-objective optimization and control

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CHEMICAL ENGINEERING RESEARCH & DESIGN 2021年 168卷 340-356页

作者： Liu, Jiyan Ren, Junyao Yang, Yilei Liu, Xinglong Sun, Lanyi China Univ Petr East China Coll Chem Engn State Key Lab Heavy Oil Proc Qingdao 266580 Shandong Peoples R China

As a process intensification technology, semicontinuous distillation uses less equipment to achieve the separation of multiple components. However, there is still a lack of systematic guidance for the design of semicontinuous distillation. In this paper, we propose a new method to guide the design of semicontinuous distillation via multi-objective optimization (MOO) and control. Conventional continuous distillation, dividing wall column (DWC) distillation and semicontinuous distillation for separation of n-alkanes are optimized through multi-objective genetic algorithm (MOGA). Several different control schemes are proposed for semicontinuous distillation, and the temperature-concentration cascade control scheme C55 is selected as the optimal control scheme. The economic benefits of semicontinuous distillation based on dynamic simulation are evaluated by the comparison with the conventional continuous distillation and DWC under a series of throughput. It is found that the total annual cost (TAC) of the semicontinuous distillation is smaller than that of conventional continuous distillation when the annual throughput is less than 7.73 x 10(4) kmol/yr. And the TAC of the semicontinuous distillation is less than that of DWC when the annual throughput is less than 5.29 x 10(4) kmol/yr. Therefore, we can conclude that the semicontinuous distillation has better economic benefits than the other two configurations within the smaller annual throughput. (C) 2021 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

关键词： Semicontinuous distillation N-alkanes multi-objective genetic algorithm Process control Economic evaluation

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Optimization of the driver's seat belt and injury biomechanical analysis in real-world minivan small offset impact accident scenarios

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FRONTIERS IN BIOENGINEERING AND BIOTECHNOLOGY 2022年 10卷 965206页

作者： Yang, Xiuju Shi, Jingjing Fu, Qianying Pu, Shanshan Lian, Chunxiao Li, Kui Yin, Zhiyong Liu, Shengxiong Wang, Guixue Chongqing Univ State & Local Joint Engn Lab Vasc Implants Key Lab Biorheol Sci & Technol Coll BioengnMinist Educ Chongqing Peoples R China Chongqing Univ Technol Dept Biomed Engn Coll Pharm & Bioengn Chongqing Peoples R China Army Med Univ Chongqing Key Lab Vehicle Crash Bioimpact & Traff Dept 4 Inst Surg ResDaping Hosp Chongqing Peoples R China China Automot Engn Res Inst Co Ltd Chongqing Peoples R China

To minimize injuries and protect the safety of the driver in minivan small offset collisions, an optimized pre-tensioned force-limiting seat belt was proposed herein. An accident with detailed information, such as medical reports, vehicle inspection reports, and accident scene photographs, was reconstructed using HyperMesh software. The effectiveness of both the accident model and the pre-tensioned force-limiting seat belt was evaluated. To obtain the optimal seat belt parameters for driver protection, first, force-limiting A, pre-tensioned force B, and pre-tensioned time C factors were selected in designing an orthogonal test with different factor levels. The influence laws of each factor on the injury biomechanical characteristics of the driver were analyzed via the direct analysis method. Moreover, each kind of critical injury value of the human body was synthesized, and the radial basis function surrogate model was constructed. The three seat belt parameters were optimized using the NSGA-II multi-objective genetic algorithm. The results showed that the optimal balance variable parameter of the seat belt was 4751.618 N-2451.839 N-17.554 ms (A-B-C). Finally, the optimal scheme was verified in a system simulating a minivan small offset collision. The results showed that after optimization, the skull von Mises stress was reduced by 36.9%, and the stress of the cervical vertebra cortical bone and cancellous bone decreased by 29.1% and 30.8%, respectively. In addition, the strains of the ribs and lungs decreased by 31.2% and 30.7%, respectively.

关键词： small offset collision accident reconstruction driver injury pre-tensioned force-limiting seat belt multi-objective genetic algorithm biomechanics analysis genetic algorithm

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Adapting multireservoir Operation to Shifting Patterns of Water Supply and Demand

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WATER RESOURCES MANAGEMENT 2014年第3期28卷 625-643页

作者： Vonk, E. Xu, Y. P. Booij, M. J. Zhang, X. Augustijn, D. C. M. Univ Twente Dept Water Engn & Management NL-7522 NB Enschede Netherlands Zhejiang Univ Inst Hydrol & Water Resources Hangzhou 310058 Zhejiang Peoples R China

The aim of this study is to determine whether dam reoperation (the adjustment of reservoir operating rules) is an effective adaptation strategy to reduce the potential impacts of climate change and regional socio-economic developments. The Xinanjiang-Fuchunjiang reservoir cascade, located in Hangzhou Region (China), is selected as case study. We use a scenario-based approach to explore the effects of various likely degrees of water stress for the future period between 2011 and 2040, which are compared to the control period from 1971 to 2000. The scenario impacts are simulated with the WEAP water allocation model, which is interlinked with the NSGA-II metaheuristic algorithm in order to derive optimal operating rules adapted to each scenario. Reservoir performance is measured with the Shortage Index (SI) and Mean Annual Energy Production (MAEP). For the investigated scenarios, adapted operating rules on average reduce the SI with 84 % and increase the MAEP with 6.4 % (compared to the projected future performance of conventional operation). Based on the optimization results, we conclude that for the studied case dam reoperation is an effective adaptation strategy to reduce the impact of changing patterns of water supply and demand, even though it is insufficient to completely restore system performance to that of the control period.

关键词： Reservoir operation multi-objective genetic algorithm WEAP multireservoir system Climate adaptation Scenario analysis

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Influence of solution heat treatment on mechanical response and fracture behaviour of aluminium alloy sheets: An experimental study

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MATERIALS & DESIGN 2015年 88卷 1119-1126页

作者： Ma, Wenyu Wang, Baoyu Yang, Lei Tang, Xuefeng Xiao, Wenchao Zhou, Jing Univ Sci & Technol Beijing Sch Mech Engn Beijing 100083 Peoples R China

Solution heat treatment (SHT), as a part of a consolidated process involving quenching and artificial ageing, significantly affects the mechanical properties of AA6082 sheets. In this study, SHT temperature and time were analysed as main design variables. Specimens were subjected to SHT by using central composite design and then processed by water quenching and artificial ageing (190 degrees C/3 h). Tension tests were conducted at room temperature to measure the tensile strength and formability of the specimens. Response surface models for ultimate tensile stress (UTS) and ductility were constructed as a function of the design variables. UTS generally increased and ductility decreased with increasing SHT temperature and time. This result was processed using the multiobjective sorting genetic algorithm NSGA-II to optimise design parameters and improve UTS and ductility. Pareto optimal solutions corresponding to UTS and ductility and appropriate ranges of design variables were obtained. The fracture characteristics of the alloy parts formed after tensile tests were further analysed using scanning electron microscopy. The fracture mode was the ductile fracture. Increasing SHT temperature and time made the dimples to be shallow and less. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Aluminium alloy Solution heat treatment Response surface model multi-objective genetic algorithm Fracture morphology

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Direct method for uncertain multi-objective optimization based on interval non-dominated sorting

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STRUCTURAL AND multiDISCIPLINARY OPTIMIZATION 2020年第2期62卷 729-745页

作者： Liu, Guiping Liu, Sheng Hunan Univ Coll Mech & Vehicle Engn State Key Lab Adv Design & Mfg Vehicle Body Changsha 410082 Hunan Peoples R China

The interval optimization methods which describe the uncertainty by intervals are widely used in uncertain multi-objective optimization. Commonly, the interval values of the objective functions are substituted by approximate values, which will cause the loss of accuracy. To deal with the problem, a direct method is presented in this paper. In the framework of the multi-objective genetic algorithm, the upper and lower boundaries of the objective and constraint functions are found using the Monte Carlo stochastic simulation method and the constraints are handled by the degree of interval constraint violation;and then every two individuals from the combination population of the evolutionary population and the external elite population are compared using the interval comparison method. Afterwards, an interval non-dominated sorting based on the interval dominance relations is performed to sort the combination population into different non-dominated level. Furthermore, a general crowding distance is calculated for each individual to make individuals from the same non-dominated level comparable and also to maintain the diversity. The efficiency and accuracy of the proposed method is demonstrated by three test functions, the multi-objective structural optimization of the ten-bar truss, and the multi-objective structural optimization of a vehicle body for crashworthiness and lightweight.

关键词： Uncertain multi-objective optimization Interval non-dominated sorting General crowding distance multi-objective genetic algorithm Crashworthiness

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Optimal energy management of microgrid using advanced multi-objective particle swarm optimization

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ENGINEERING COMPUTATIONS 2020年第6期37卷 2085-2110页

作者： Anh, Ho Pham Huy Kien, Cao Van Ho Chi Minh City Univ Technol VNU HCM FEEE Ho Chi Minh City Vietnam Ind Univ Ho Chi Minh City Fac Elect Technol Ho Chi Minh City Vietnam

Purpose The purpose of this paper is to propose an optimal energy management (OEM) method using intelligent optimization techniques applied to implement an optimally hybrid heat and power isolated microgrid. The microgrid investigated combines renewable and conventional power generation. Design/methodology/approach Five bio-inspired optimization methods include an advanced proposed multi-objective particle swarm optimization (MOPSO) approach which is comparatively applied for OEM of the implemented microgrid with other bio-inspired optimization approaches via their comparative simulation results. Findings Optimal multi-objective solutions through Pareto front demonstrate that the advanced proposed MOPSO method performs quite better in comparison with other meta-heuristic optimization methods. Moreover, the proposed MOPSO is successfully applied to perform 24-h OEM microgrid. The simulation results also display the merits of the real time optimization along with the arbitrary of users' selection as to satisfy their power requirement. Originality/value This paper focuses on the OEM of a designed microgrid using a newly proposed modified MOPSO algorithm. Optimal multi-objective solutions through Pareto front demonstrate that the advanced proposed MOPSO method performs quite better in comparison with other meta-heuristic optimization approaches.

关键词： Optimal energy management Hybrid microgrid multi-objective genetic algorithm multi-objective particle swarm optimization algorithm 24-hour optimal energy management simulations Bio-inspired optimization methods

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