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MULTIAXIAL CREEP-FATIGUE LIFE EVALUATION UNDER PROPORTIONAL LOADING 被引量:3
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作者 Y.Noguchi M.Miyahara 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2004年第4期355-360,共6页
A new method was proposed for the multiaxial creep-fatigue life evaluation under proportional loadings. Because this method was derived from the strain range partitioning method with a multiaxiality factor, it was pos... A new method was proposed for the multiaxial creep-fatigue life evaluation under proportional loadings. Because this method was derived from the strain range partitioning method with a multiaxiality factor, it was possible to consider the influence of both creep-fatigue interaction and multiaxial stress state on fatigue life. In order to predict the combined axial-torsional fatigue life the damage under combined loading was defined as linear summation of the damages under axial loading and torsional loading. Axial-torsional creep-fatigue tests were carried out using tubular specimens of 316LC austenitic stainless steel and the ferritic rotor steel. This rotor steel was developed for the permanent magnet type eddy current retarder in heavy trucks. Experimentally obtained lives of both steels were well corresponded with the lives predicted by the proposed method. It was found that the proposed method was effective in multiaxial fatigue life evaluation under proportional creep-fatigue loadings. 展开更多
关键词 multiaxial fatigue CREEP-FATIGUE proportional loading life evaluation
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Fatigue characteristics and microcosmic mechanism of Al-Si-Mg alloys under multiaxial proportional loadings 被引量:1
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作者 Xiao-song Jiang Guo-qiu He +2 位作者 Bing Liu Zheng-yu Zhu Wei-hua Zhang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2011年第4期437-443,共7页
With the increasing use of Al-Si-Mg alloys in the automotive industry,the fatigue performance of Al-Si-Mg alloy has become a major concern with regard to their reliability.The fatigue characteristics and microcosmic m... With the increasing use of Al-Si-Mg alloys in the automotive industry,the fatigue performance of Al-Si-Mg alloy has become a major concern with regard to their reliability.The fatigue characteristics and microcosmic mechanism of an Al-Si-Mg alloy under multiaxial proportional loadings were investigated in this research.As low cycle fatigue life and material strengthening behavior are closely related,the effect of equivalent strain amplitude on the multiaxial fatigue properties was analyzed.Fatigue tests were conducted to determine the influence of equivalent strain amplitude on the multiaxial proportional fatigue properties.The fatigue life exhibits a stable behavior under multiaxial proportional loadings.The dislocation structures of the Al-Si-Mg alloy were observed by transmission electron microscopy(TEM).The dislocation structure evolution of the Al-Si-Mg alloy under multiaxial proportional loadings during low cycle fatigue develops step by step by increasing fatigue cycles.Simultaneously,the dislocation structure changes with the change in equivalent strain amplitude under multiaxial proportional loadings.The experimental evidence indicates that the multiaxial fatigue behavior and life are strongly dependent on the microstructure of the material,which is caused by multiaxial proportional loadings. 展开更多
关键词 aluminum alloys proportional loadings FATIGUE MICROSTRUCTURE
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EFFECT OF NON-PROPORTIONAL OVERLOADING ON FATIGUE CRACK GROWTH
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作者 GAO Hua CHEN Youxuan LI Ming Shanghai University of Engineering Science,Shanghai,ChinaCHEN Dehai Shanghai Dalong Machinery,Shanghai,China Associate Professor,Dept.of Materials,Shanghai University of Engineering Science,Shanghai 200051,China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1991年第1期59-64,共6页
The effect of proportional and non-proportional overloading on mode l fatigue crack growth have been studied,and the influences of crack tip plastic zone,crack tip blunting as well as crack closure were discussed.Prop... The effect of proportional and non-proportional overloading on mode l fatigue crack growth have been studied,and the influences of crack tip plastic zone,crack tip blunting as well as crack closure were discussed.Proportional(model I)overloading may cause more serious crack growth retardation than non-proportional(mixed mode)overloading.Therefore,for estimating the fatigue life of engineering structures to simplify a real overload which may of- ten be non-proportional as a proportional one is not always safe. 展开更多
关键词 non-proportional overloading fatigue crack growth mixed mode loading
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Water-Assisted Injection Molding System Based on Water Hydraulic Proportional Control Technique 被引量:5
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作者 ZHOU Hua ZHANG Zengmeng +1 位作者 GAO Yuan'an YANG Huayong 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2010年第4期418-427,共10页
Water-assisted injection molding(WAIM), an innovative process to mold plastic parts with hollow sections, is characterized with intermittent, periodic process and large pressure and flow rate variation. Energy savin... Water-assisted injection molding(WAIM), an innovative process to mold plastic parts with hollow sections, is characterized with intermittent, periodic process and large pressure and flow rate variation. Energy savings and injection pressure control can not be .attained based on conventional valve control system. Moreover, the injection water can not be supplied directly by water hydraulic proportional control system. Poor efficiency and control performance are presented by current trial systems, which pressurize injection water by compressed air. In this paper, a novel water hydraulic system is developed applying an accumulator for energy saving. And a new differential pressure control method is proposed by using pressure cylinder and water hydraulic proportional pressure relief valve for back pressure control. Aiming at design of linear controller for injection water pressure regulation, a linear load model is approximately built through computational fluid dynamics(CFD) simulation on two-phase flow cavity filling process with variable temperature and viscosity, and a linear model of pressure control system is built with the load model and linearization of water hydraulic components. According to the simulation, model based feedback is brought forward to compensate the pressure decrease during accumulator discharge and eliminate the derivative element of the system. Meanwhile, the steady-state error can be reduced and the capacity of resisting disturbance can be enhanced, by closed-loop control of load pressure with integral compensation. Through the developed experimental system in the State Key Lab of Fluid Power Transmission and Control, Zhejiang University, China, the static characteristic of the water hydraulic proportional relief valve was tested and output pressure control of the system in Acrylonitrile Butadiene Styrene(ABS) parts molding experiments was also studied. The experiment results show that the dead band and hysteresis of the water hydraulic proportional pressure relief valve are large, but the control precision and linearity can be improved with feed-forward compensation. With the experimental results of injection water pressure control, the applicability of this WAIM system and the effect of its linear controller are verified. The novel proposed process of WAIM pressure control and study on characteristics of control system contribute to the application of water hydraulic proportional control and WAIM technology. 展开更多
关键词 water-assisted injection molding water hydraulics proportional pressure control linear control load characteristic
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Experimental Study on Non-proportional Multiaxial Strain Cyclic Characteristics and Ratcheting of U71Mn Rail Steel 被引量:6
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作者 Guozheng KANG, Qing GAO, Lixun CAI, Yafang SUN and Xianjie YANGDepartment of Applied Mechanics and Engineering, Southwest Jiaotong University, Chengdu 610031, China 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2002年第1期13-16,共4页
An experimental study was carried out on the strain cyclic characteristics and ratcheting of U71Mn rail steel subjected to non-proportional multiaxial cyclic loading. The strain cyclic characteristics were researched ... An experimental study was carried out on the strain cyclic characteristics and ratcheting of U71Mn rail steel subjected to non-proportional multiaxial cyclic loading. The strain cyclic characteristics were researched under the strain-controlled circular load path. The ratcheting was investigated for the stress-controlled multiaxial circular, elliptical and rhombic load paths with different mean stresses, stress amplitudes and their histories. The experiment shows that U71Mn rail steel features the cyclic non-hardening/softening, and its strain cyclic characteristics depend greatly on the strain amplitude but slightly on its history. However, the ratcheting of U71Mn rail steel depends greatly not only on the values of mean stress and stress amplitude, but also on their histories. In the meantime, the shape of load path and its history also apparently influence the ratcheting. The ratcheting changes with the different loading paths. 展开更多
关键词 U71 Mn steel RATCHETING Cyclic plasticity Non-proportional load
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Analytic Formulae for Estimating Motor Proportion of Load Model Under Small Disturbance
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作者 Ping Ju Shiqiu Xia +1 位作者 Yuqing Jin Lu Cao 《CSEE Journal of Power and Energy Systems》 SCIE EI CSCD 2024年第4期1599-1607,共9页
In the composite load model(CLM),which is commonly used in China,an equivalent motor and equivalent static load are used to represent all electrical equipment and networks connected to a load bus.Existing research has... In the composite load model(CLM),which is commonly used in China,an equivalent motor and equivalent static load are used to represent all electrical equipment and networks connected to a load bus.Existing research has determined typical values of electrical and mechanical parameters for load models of different load types,which improves the basis for load modeling.However,the motor proportion parameter is not the same for different load buses or at different times;therefore,obtaining the actual motor proportion is key to establishing an accurate load model.In the existing load modeling method,motor proportion is commonly identified along with other parameters under rare large disturbances;therefore,the value of the motor proportion is fixed by the time when a large disturbance occurs.In this paper,formulae are derived to estimate motor proportion under small disturbances,and these formulae allow direct calculation of motor proportion without using any optimization algorithm.The proposed estimation formulae do not rely on any parameters of load model or power system but instead rely only on measurement of the voltage and active power at steady-state points before and after a small disturbance.Because of universality of small disturbances in power systems,estimating time-varying motor proportion under small disturbances will be helpful for solving the time-varying problem of load models.Finally,the proposed motor proportion estimation formulae are validated by simulations,physical experiments,and field experiments. 展开更多
关键词 Composite load model load modeling motor proportion parameter estimation
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Elastoplastic solutions for single piles under combined vertical and lateral loads 被引量:16
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作者 ZHANG Lei GONG Xiao-nan +1 位作者 YANG Zhong-xuan YU Jian-lin 《Journal of Central South University》 SCIE EI CAS 2011年第1期216-222,共7页
In order to improve the reliability of the design and calculation of single piles under the combined vertical and lateral loads, the solutions were presented based on the subgrade reaction method, in which the ultimat... In order to improve the reliability of the design and calculation of single piles under the combined vertical and lateral loads, the solutions were presented based on the subgrade reaction method, in which the ultimate soil resistance was considered and the coefficient of subgrade reaction was assumed to be a constant. The corresponding computational program was developed using FORTRAN language. A comparison between the obtained solutions and the model test results was made to show the validity of the obtained solutions. The calculation results indicate that both the maximum lateral displacement and bending moment increase with the increase of the vertical and lateral loads and the pile length above ground, while decrease as the pile stiffness, the coefficient of subgrade reaction and the yielding displacement of soil increase. It is also shown that the pile head condition controls the pile responses and the vertical load may cause the instability problem to the pile. In general, the proposed method can be employed to calculate the pile responses independent of the magnitude of the pile deflection. 展开更多
关键词 pile-soil interaction combined vertical and lateral loads ultimate resistance subgrade reaction method bendingmoment
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Numerical modeling of centrifuge cyclic lateral pile load experiments 被引量:8
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作者 Nikos Gerolymos Sandra Escoffier +1 位作者 George Gazetas Jacques Garnier 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2009年第1期61-76,共16页
To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoir... To gain insight into the inelastic behavior of piles, the response of a vertical pile embedded in dry sand and subjected to cyclic lateral loading was studied experimentally in centrifuge tests conducted in Laboratoire Central des Ponts et Chaussees. Three types of cyclic loading were applied, two asymmetric and one symmetric with respect to the unloaded pile. An approximately square-root variation of soil stiffness with depth was obtained from indirect in-flight density measurements, laboratory tests on reconstituted samples, and well-established empirical correlations. The tests were simulated using a cyclic nonlinear Winkler spring model, which describes the full range of inelastic phenomena, including separation and re-attachment of the pile from and to the soil. The model consists of three mathematical expressions capable of reproducing a wide variety of monotonic and cyclic experimentalp-y curves. The physical meaning of key model parameters is graphically explained and related to soil behavior. Comparisons with the centrifuge test results demonstrate the general validity of the model and its ability to capture several features of pile-soil interaction, including: soil plastification at an early stage of loading, "pinching" behavior due to the formation of a relaxation zone around the upper part of the pile, and stiffness and strength changes due to cyclic loading. A comparison of the p-y curves derived from the test results and the proposed model, as well as those from the classical curves of Reese et al. (1974) for sand, is also presented. 展开更多
关键词 centrifuge test Winkler model p-y curves cyclic loading pile-soil separation/gapping nonlinear response experimental validation
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Numerical simulation on behavior of pile foundations under cyclic axial loads 被引量:4
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作者 ZHAO Ming-hua HENG Shuai ZHENG Yue 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第12期2906-2913,共8页
On the basis of the two dimensional finite element analysis model, the pile foundations' mechanical effect of the rigid pile composite foundation under the dynamic load was researched. Through the research, the de... On the basis of the two dimensional finite element analysis model, the pile foundations' mechanical effect of the rigid pile composite foundation under the dynamic load was researched. Through the research, the development law and deformation property of axial force of pile body, shaft resistance of pile, and cumulative settlement of pile head under vertical cyclic dynamic loads were concluded. Through the comparison and analysis of the test results of dynamic models, the test results of Poulos(1989) and cumulative settlement model of the single pile under cyclic loads were confirmed. Based on the above research, Fortran language was adopted to introduce the soil attenuation factor, the secondary development of relevant modules of ABAQUS was carried out, and the effect of soil attenuation factor on dynamic property of pile-soil was discussed further. 展开更多
关键词 PILE FOUNDATION ABAQUS CYCLIC dynamic load numerical simulation pile-soil interaction SECONDARY development
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Comparison of Pile-Soil-Structure Interaction Modeling Techniques for A 10-MW Large-Scale Monopile Wind Turbine Model Under Wind and Wave Conditions 被引量:2
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作者 ZENG Yu-xin ZHANG Xiao-ming +3 位作者 ZHANG Li-xian SHI Wei WANG Wen-hua LI Xin 《China Ocean Engineering》 SCIE EI CSCD 2023年第3期471-483,共13页
Considering the large diameter effect of piles,the influence of different pile-soil analysis methods on the design of monopile foundations for offshore wind turbines has become an urgent problem to be solved.Three dif... Considering the large diameter effect of piles,the influence of different pile-soil analysis methods on the design of monopile foundations for offshore wind turbines has become an urgent problem to be solved.Three different pile-soil models were used to study a large 10 MW monopile wind turbine.By modeling the three models in the SACS software,this paper analyzed the motion response of the overall structure under the conditions of wind and waves.According to the given working conditions,this paper concludes that under the condition of independent wind,the average value of the tower top x-displacement of the rigid connection method is the smalle st,and the standard deviation is the smallest under the condition of independent wave.The results obtained by the p-y curve method are the most conservative. 展开更多
关键词 large-scale monopile offshore wind turbine pile-soil model wind-wave load combination
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Multi-objective optimization of multi-cell conical structures under dynamic loads 被引量:2
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作者 PIRMOHAMMAD Sadjad ESMAEILI-MARZDASHTI Sobhan 《Journal of Central South University》 SCIE EI CAS CSCD 2019年第9期2464-2481,共18页
In this paper,crashworthiness performance of multi-cell conical tubes with new sectional configuration design(i.e.square,hexagonal,octagonal,decagon and circular)has been evaluated under axial and three different obli... In this paper,crashworthiness performance of multi-cell conical tubes with new sectional configuration design(i.e.square,hexagonal,octagonal,decagon and circular)has been evaluated under axial and three different oblique loads.The same weight conical tubes were comparatively studied using an experimentally validated finite element model generated in LS-DYNA.Complex proportional assessment(COPRAS)method was then employed to select the most efficient tube using two conflicting criteria,namely peak collapse force(PCF)and energy absorption(EA).From the COPRAS calculations,the multi-cell conical tube with decagonal cross-section(MCDT)showed the best crashworthiness performance.Furthermore,the effects of possible number of inside ribs on the crashworthiness of the decagonal conical tubes were also evaluated,and the results displayed that the tubes performed better as the number of ribs increased.Finally,parameters(the cone angle,θ,and ratio of the internal tube size to the external one,S)of MCDT were optimized by adopting artificial neural networks(ANN)and genetic algorithm(GA)techniques.Based on the multi-objective optimization results,the optimum dimension parameters were found to beθ=7.9o,S=0.46 andθ=8o,S=0.74 from the minimum distance selection(MDS)and COPRAS methods,respectively. 展开更多
关键词 CRASHWORTHINESS multi-cell conical tube axial and oblique loads complex proportional assessment(COPRAS) multi-objective optimization
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Design and Experiment of Electronic-hydraulic Loading Test-bed Based on Tractor's Hydraulic Steering By-wire 被引量:1
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作者 Yue JIN Yang LU +3 位作者 Jiahui GONG Zhixiong LU Wenming LI Jungan WU 《Asian Agricultural Research》 2015年第12期86-89,共4页
An Electro-hydraulic loading system is designed based on a test-bed of tractor's hydraulic steering by-wire. To simulate the steering resistance driving tractor in many kinds of soils and roads,the loading force i... An Electro-hydraulic loading system is designed based on a test-bed of tractor's hydraulic steering by-wire. To simulate the steering resistance driving tractor in many kinds of soils and roads,the loading force is controlled to make proportional and continuous variable by an electro-hydraulic proportional relief valve. A steering resistance loading test-bed is built to test three kinds of steering resistance including constant,step and sine style. Tire lateral resistance is also tested under different steering conditions. The result shows that the electro-hydraulic loading system has high stability and following performance. Besides,the system's steady state error is lower than 3. 1%,and it meets the test requirement of tractor's hydraulic steering by-wire. 展开更多
关键词 TRACTOR Hydraulic steering by-wire loading system ELECTRO-HYDRAULIC proportional RELIEF valve BENCH test
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Elastic solutions for partially embedded single piles subjected to simultaneous axial and lateral loading 被引量:4
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作者 张磊 龚晓南 俞建霖 《Journal of Central South University》 SCIE EI CAS 2014年第11期4330-4337,共8页
In order to improve the design level of partially embedded single piles under simultaneous axial and lateral loads, the differential solutions were deduced, in which the soil was treated as an ideal, elastic, homogene... In order to improve the design level of partially embedded single piles under simultaneous axial and lateral loads, the differential solutions were deduced, in which the soil was treated as an ideal, elastic, homogeneous, semi-infinite isotropic medium. A comparison was made between model test results and the obtained solutions to show their validity. The calculation results indicate that the horizontal displacement and bending moment of the pile increase with increases of the axial and lateral loads. The maximum horizontal displacement and bending moment decrease by 37.9% and 13.9%, respectively, when the elastic modulus of soil increases from 4 MPa to 20 MPa. The Poisson ratio of soil plays a marginal role in pile responses. There is a critical pile length under the ground, beyond which the pile behaves as though it was infinitely long. The presented solutions can make allowance for the continuous nature of soil, and if condition permits, they can approach exact ones. 展开更多
关键词 pile-soil interaction simultaneous axial and lateral loads difference method elastic modulus displacement
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Morphological evolution and flow conduction characteristics of fracture channels in fractured sandstone under cyclic loading and unloading 被引量:1
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作者 Quanle Zou Zihan Chen +4 位作者 Jinfei Zhan Chunmei Chen Shikang Gao Fanjie Kong Xiaofeng Xia 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第12期1527-1540,共14页
In coal mining,rock strata are fractured under cyclic loading and unloading to form fracture channels.Fracture channels are the main flow narrows for gas.Therefore,expounding the flow conductivity of fracture channels... In coal mining,rock strata are fractured under cyclic loading and unloading to form fracture channels.Fracture channels are the main flow narrows for gas.Therefore,expounding the flow conductivity of fracture channels in rocks on fluids is significant for gas flow in rock strata.In this regard,graded incremental cyclic loading and unloading experiments were conducted on sandstones with different initial stress levels.Then,the three-dimensional models for fracture channels in sandstones were established.Finally,the fracture channel percentages were used to reflect the flow conductivity of fracture channels.The study revealed how the particle size distribution of fractured sandstone affects the formation and expansion of fracture channels.It was found that a smaller proportion of large blocks and a higher proportion of small blocks after sandstone fails contribute more to the formation of fracture channels.The proportion of fracture channels in fractured rock can indicate the flow conductivity of those channels.When the proportion of fracture channels varies gently,fluids flow evenly through those channels.However,if the proportion of fracture channels varies significantly,it can greatly affect the flow rate of fluids.The research results contribute to revealing the morphological evolution and flow conductivity of fracture channels in sandstone and then provide a theoretical basis for clarifying the gas flow pattern in the rock strata of coal mines. 展开更多
关键词 CT imaging Flow conductivity Three-dimensional reconstruction proportion of fracture channels Cyclic loading and unloading
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Design of Nichols PID Controller for Load Frequency Control 被引量:10
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作者 KONG Fannie LI Xiaocong +1 位作者 WU Jiekang GUO Zhuangzhi 《中国电机工程学报》 EI CSCD 北大核心 2012年第22期I0011-I0011,15,共1页
为解决互联水电系统负荷频率控制(load frequencycontrol,LFC)问题,及保持互联电网系统频率、联络线功率及区域控制误差(area control error,ACE)的稳定,根据闭环系统谐振峰值与系统响应最大峰值之间的关系,构建一个与系统参数及控... 为解决互联水电系统负荷频率控制(load frequencycontrol,LFC)问题,及保持互联电网系统频率、联络线功率及区域控制误差(area control error,ACE)的稳定,根据闭环系统谐振峰值与系统响应最大峰值之间的关系,构建一个与系统参数及控制器参数都相关的优化问题,通过该问题的求解获得控制器参数与系统参数之间的数学关系,针对水轮发电系统非最小相位特性,通过串加比例–微分(proportional-derivative,PD)控制方式降低系统阶次,设计尼科尔斯(Nichols)曲线的比例–积分–微分(proportional-integral-derivative,PID)控制器。基于模型参数扰动和负荷干扰的仿真结果表明:尼科尔斯PID控制器能快速调整系统频率偏差、联络线功率偏差及ACE为0,具有良好的鲁棒性能和抗负荷干扰性能,系统过渡过程性能明显优于传统PID调节器结果。 展开更多
关键词 负荷频率控制 PID控制器 设计 区域控制误差 自动控制理论 电力系统稳定 水电系统 提出问题
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EXPERIMENTAL INVESTIGATION ON FATIGUE CRACK PROPAGATION UNDER TENSION-TORSION LOADING
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作者 WANGYing-yu YAOWei-xing 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2004年第4期263-266,共4页
Various proportional and nonproportional tension-torsion fatigue tests are conducted on aeronautical material-LY12CZ aluminum alloy. The stress and strain states under tension-torsion loading are analyzed by an elasti... Various proportional and nonproportional tension-torsion fatigue tests are conducted on aeronautical material-LY12CZ aluminum alloy. The stress and strain states under tension-torsion loading are analyzed by an elastic-plastic finite element method. The relation between the orientation of crack propagation and each stress and strain component is investigated. Analytical results are compared with experimental data. Results demonstrate that the fatigue cracks tend to be propagated perpendicular to the direction of the largest principle strains under proportional loading, and grow alone one of the maximum shear strain planes under 45° and 90° out-of-phase loadings. 展开更多
关键词 multi-axial fatigue crack propagation proportional loading non-proportional loading
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Kautz Function Based Continuous-Time Model Predictive Controller for Load Frequency Control in a Multi-Area Power System
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作者 A.Parassuram P.Somasundaram 《Computer Modeling in Engineering & Sciences》 SCIE EI 2018年第11期169-187,共19页
A continuous-time Model Predictive Controller was proposed using Kautz function in order to improve the performance of Load Frequency Control(LFC).A dynamic model of an interconnected power system was used for Model P... A continuous-time Model Predictive Controller was proposed using Kautz function in order to improve the performance of Load Frequency Control(LFC).A dynamic model of an interconnected power system was used for Model Predictive Controller(MPC)design.MPC predicts the future trajectory of the dynamic model by calculating the optimal closed loop feedback gain matrix.In this paper,the optimal closed loop feedback gain matrix was calculated using Kautz function.Being an Orthonormal Basis Function(OBF),Kautz function has an advantage of solving complex pole-based nonlinear system.Genetic Algorithm(GA)was applied to optimally tune the Kautz function-based MPC.A constraint based on phase plane analysis was implemented with the cost function in order to improve the robustness of the Kautz function-based MPC.The proposed method was simulated with three area interconnected power system and the efficiency of the proposed method was measured and exhibited by comparing with conventional Proportional and Integral(PI)controller and Linear Quadratic Regulation(LQR). 展开更多
关键词 load frequency control model PREDICTIVE CONTROLLER orthonormal basis FUNCTION kautz FUNCTION phase plane analysis linear QUADRATIC REGULATOR proportional and integral CONTROLLER genetic algorithm.
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APPLICATION OF NONLINEAR PID CONTROLLER IN AERODYNAMICS LOADING SYSTEM
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作者 Hu Fei Cai Xiaobin Li Yanjun(Department of Computer Science, Northwesternm PolytechnicalUniversity, Xi’an, 710072, China) 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 1997年第2期155-160,共6页
The design idea of tracking-differentiator and the nonlinear PID controllerare introduced, the applicable algorithm and its real result for distributed aerodynamicsloading control system are discussed, and the constru... The design idea of tracking-differentiator and the nonlinear PID controllerare introduced, the applicable algorithm and its real result for distributed aerodynamicsloading control system are discussed, and the construction of the test & contro1 system arealso presented. The application shows that the nonlinear PID algorithm has the advan-tages of high reliability, short run time and strong stability. 展开更多
关键词 aerodynamic loads NONLINEARITY proportional-integral-differential (controller) controllers test & control systems
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A Novel Flower Pollination Algorithm to Solve Load Frequency Control for a Hydro-Thermal Deregulated Power System
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作者 D. Lakshmi A. Peer Fathima Ranganath Muthu 《Circuits and Systems》 2016年第4期166-178,共13页
Load frequency control plays a vital role in power system operation and control. LFC regulates the frequency of larger interconnected power systems and keeps the net interchange of power between the pool members at pr... Load frequency control plays a vital role in power system operation and control. LFC regulates the frequency of larger interconnected power systems and keeps the net interchange of power between the pool members at predetermined values for the corresponding changes in load demand. In this paper, the two-area, hydrothermal deregulated power system is considered with Redox Flow Batteries (RFB) in both the areas. RFB is an energy storage device, which converts electrical energy into chemical energy, that is used to meet the sudden requirement of real power load and hence very effective in reducing the peak shoots. With conventional proportional-integral (PI) controller, it is difficult to get the optimum solution. Hence, intelligent techniques are used to tune the PI controller of the LFC to improve the dynamic response. In the family of intelligent techniques, a recent nature inspired algorithm called the Flower Pollination Algorithm (FPA) gives the global minima solution. The optimal value of the controller is determined by minimizing the ISE. The results show that the proposed FPA tuned PI controller improves the dynamic response of the deregulated system faster than the PI controller for different cases. The simulation is implemented in MATLAB environment. 展开更多
关键词 load Frequency Control Redox Flow Battery proportional Integral Controller Flower Pollination Algorithm
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进气歧管喷水对发动机燃烧性能的试验研究
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作者 叶坦 王雷 曹永 《机械科学与技术》 CSCD 北大核心 2024年第1期45-53,共9页
为研究进气歧管喷水技术对汽油发动机热效率的提升潜力,基于一台研究型单缸汽油发动机,采用试验的手段对比研究了不同的喷水比例、不同的负荷工况及不同的压缩比下进气歧管喷水对发动机燃烧性能的影响。结果表明,采用进气歧管喷水技术... 为研究进气歧管喷水技术对汽油发动机热效率的提升潜力,基于一台研究型单缸汽油发动机,采用试验的手段对比研究了不同的喷水比例、不同的负荷工况及不同的压缩比下进气歧管喷水对发动机燃烧性能的影响。结果表明,采用进气歧管喷水技术可有效降低发动机的爆震趋势,随着喷水比例的增加,CA50逐渐提前,燃料的滞燃期及燃烧持续期增加,同时伴随着传热损失逐渐增加。相比于无喷水(w/o PWI)的结果,喷水的引入虽然导致未燃损失增加,但有利于排气能量损失大幅降低,最终反应到经济性的表现为热效率随着喷水比例的增大呈先增加后降低的趋势,油耗率的表现同热效率的结果相反;此时最佳的净指示热效率(GITE)为43.1%,相比于w/o PWI的结果升高了2.5%;最佳的净指示油耗率(GISFC)为197.9 g/(kW·h),相比于w/o PWI的结果降低了11.8 g/(kW·h)。高负荷运用喷水技术将达到更显著的热效率改善及油耗改善效果;同时,喷水技术的引入使得发动机高压缩比的应用成为可能。 展开更多
关键词 进气歧管喷水 喷水比例 负荷 压缩比 燃烧性能
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