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Exploration of instantaneous frequency for local control assessment in real-time hybrid simulation
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作者 Xu Weijie Peng Changle +1 位作者 Guo Tong Chen Cheng 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2024年第4期995-1008,共14页
Local control parameters such as instantaneous delay and instantaneous amplitude play an essential role in evaluating the performance and maintaining the stability of real-time hybrid simulation(RTHS).However,existing... Local control parameters such as instantaneous delay and instantaneous amplitude play an essential role in evaluating the performance and maintaining the stability of real-time hybrid simulation(RTHS).However,existing methods have limitations in obtaining this local assessment in either the time domain or frequency domain.In this study,the instantaneous frequency is introduced to determine local control parameters for actuator tracking assessment in a real-time hybrid simulation.Instantaneous properties,including amplitude,delay,frequency and phase,are then calculated based on analytic signals translated from actuator tracking signals through the Hilbert transform.Potential issues are discussed and solutions are proposed for calculation of local control parameters.Numerical simulations are first conducted for sinusoidal and chirp signals with time varying amplitude error and delay to demonstrate the potential of the proposed method.Laboratory tests also are conducted for a predefined random signal as well as the RTHS of a single degree of freedom structure with a self-centering viscous damper to experimentally verify the effectiveness of the proposed use of the instantaneous frequency.Results from the ensuing analysis clearly demonstrate that the instantaneous frequency provides great potential for local control assessment,and the proposed method enables local tracking parameters with good accuracy. 展开更多
关键词 real-time hybrid simulation tracking assessment instantaneous frequency Hilbert transform
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Models to Simulate Effective Coverage of Fire Station Based on Real-Time Travel Times
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作者 Sicheng Zhu Dingli Liu +2 位作者 Weijun Liu Ying Li Tian Zhou 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第4期483-513,共31页
In recent years,frequent fire disasters have led to enormous damage in China.Effective firefighting rescues can minimize the losses caused by fires.During the rescue processes,the travel time of fire trucks can be sev... In recent years,frequent fire disasters have led to enormous damage in China.Effective firefighting rescues can minimize the losses caused by fires.During the rescue processes,the travel time of fire trucks can be severely affected by traffic conditions,changing the effective coverage of fire stations.However,it is still challenging to determine the effective coverage of fire stations considering dynamic traffic conditions.This paper addresses this issue by combining the traveling time calculationmodelwith the effective coverage simulationmodel.In addition,it proposes a new index of total effective coverage area(TECA)based on the time-weighted average of the effective coverage area(ECA)to evaluate the urban fire services.It also selects China as the case study to validate the feasibility of the models,a fire station(FS-JX)in Changsha.FS-JX station and its surrounding 9,117 fire risk points are selected as the fire service supply and demand points,respectively.A total of 196 simulation scenarios throughout a consecutiveweek are analyzed.Eventually,1,933,815 sets of valid sample data are obtained.The results showed that the TECA of FS-JX is 3.27 km^(2),which is far below the standard requirement of 7.00 km^(2) due to the traffic conditions.The visualization results showed that three rivers around FS-JX interrupt the continuity of its effective coverage.The proposed method can provide data support to optimize the locations of fire stations by accurately and dynamically determining the effective coverage of fire stations. 展开更多
关键词 Fire services fire station effective coverage real-time traffic simulation
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Hybrid Teaching Reform of Veterinary Microbiology Based on the Combination of Virtual Simulation and Problem-Based Learning
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作者 Jiedan Liao 《Journal of Contemporary Educational Research》 2024年第9期1-9,共9页
The Veterinary Microbiology course is centered around the diagnosis and testing of pathogenic microorganisms,with the core value of“moral education and character development.”It reconstructs multidimensional teachin... The Veterinary Microbiology course is centered around the diagnosis and testing of pathogenic microorganisms,with the core value of“moral education and character development.”It reconstructs multidimensional teaching resources by integrating disciplinary achievements with clinical cases and implements a hybrid teaching approach combining virtual simulation and problem-based learning(PBL)through the“three stages+four models+three reflections”framework.Dual-qualification teachers employ various teaching methods,create a“six-in-one”model for ideological and political education,and conduct formative assessments based on the principles of diversified objectives and process emphasis.The hybrid teaching reform addresses issues such as fragmented knowledge,insufficient class hours,weak animal disease diagnostic abilities among students,limited application and expansion of knowledge points,and students’lack of proactive critical thinking skills.The application of hybrid teaching has shown significant advantages and effectiveness,providing a reference for teaching reform in similar microbiology courses. 展开更多
关键词 Veterinary Microbiology hybrid teaching Virtual simulation Problem-based learning Teaching reform
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Data-based real-time petrochemical gas diffusion simulation approach on virtual reality
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作者 Min YANG Yong HAN +1 位作者 Chang SU Xue LI 《Virtual Reality & Intelligent Hardware》 2023年第3期266-278,共13页
Background Petrochemical products possess a high risk of flammability,explosivity,and toxicity,making petrochemical accidents exceedingly destructive.Therefore,disaster analysis,prediction,and real-time simulations ha... Background Petrochemical products possess a high risk of flammability,explosivity,and toxicity,making petrochemical accidents exceedingly destructive.Therefore,disaster analysis,prediction,and real-time simulations have become important means of controlling and reducing accident hazards.Methods This study proposes a complete real-time simulation solution of gas diffusion with coordinate and concentration data,which was mainly aimed at simulating the types of harmful gas leakage and diffusion accidents in the petrochemical industry.The rendering effect was more continuous and accurate through grid homogenization and trilinear interpolation.This study presents a data processing and rendering parallelization process to enhance simulation efficiency.Gas concentration and fragment transparency were combined to synthesize transparent pixels in a scene.To ensure the approximate accuracy of the rendering effect,improve the efficiency of real-time rendering,and meet the requirement of intuitive perception using concentration data,a weighted blended order-independent transparency(OIT)with enhanced alpha weight is presented,which can provide a more intuitive perception of the hierarchical information of concentration data while preserving depth information.This study compares and analyzes three OIT algorithms-depth peeling,weighted blended OIT,and weighted blended OIT with enhanced alpha weight-in terms of rendering image quality,rendering time,required memory,and hierarchical information.Results Using weighted blended OIT with an enhanced alpha weight technique,the rendering time was shortened by 53.2%compared with that of the depth peeling algorithm,and the texture memory required was significantly smaller than that of the depth peeling algorithm.The rendering results of weighted blended OIT with an enhanced alpha weight were approximately accurate compared with those of the depth peeling algorithm as the ground truth,and there was no popping when surfaces passed through one another.Simultaneously,compared with weighted blended OIT,weighted blended OIT with an enhanced alpha weight achieved an intuitive perception of the hierarchical information of concentration data. 展开更多
关键词 real-time gas diffusion simulation Trilinear interpolation Order-independent transparency rendering parallelization
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Model-based framework for multi-axial real-time hybrid simulation testing 被引量:4
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作者 Gaston A.Fermandois Billie F.Spencer,Jr. 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2017年第4期671-691,共21页
Real-time hybrid simulation is an efficient and cost-effective dynamic testing technique for performance evaluation of structural systems subjected to earthquake loading with rate-dependent behavior. A loading assembl... Real-time hybrid simulation is an efficient and cost-effective dynamic testing technique for performance evaluation of structural systems subjected to earthquake loading with rate-dependent behavior. A loading assembly with multiple actuators is required to impose realistic boundary conditions on physical specimens. However, such a testing system is expected to exhibit significant dynamic coupling of the actuators and suffer from time lags that are associated with the dynamics of the servo-hydraulic system, as well as control-structure interaction (CSI). One approach to reducing experimental errors considers a multi-input, multi-output (MIMO) controller design, yielding accurate reference tracking and noise rejection. In this paper, a framework for multi-axial real-time hybrid simulation (maRTHS) testing is presented. The methodology employs a real-time feedback-feedforward controller for multiple actuators commanded in Cartesian coordinates. Kinematic transformations between actuator space and Cartesian space are derived for all six-degrees-of- freedom of the moving platform. Then, a frequency domain identification technique is used to develop an accurate MIMO transfer function of the system. Further, a Cartesian-domain model-based feedforward-feedback controller is implemented for time lag compensation and to increase the robustness of the reference tracking for given model uncertainty. The framework is implemented using the 1/5th-scale Load and Boundary Condition Box (LBCB) located at the University of Illinois at Urbana- Champaign. To demonstrate the efficacy of the proposed methodology, a single-story frame subjected to earthquake loading is tested. One of the columns in the fraane is represented physically in the laboratory as a cantilevered steel column. For real- time execution, the numerical substructure, kinematic transformations, and controllers are implemented on a digital signal processor. Results show excellent performance of the maRTHS framework when six-degrees-of-freedom are controUed at the interface between substructures. 展开更多
关键词 real-time hybrid simulation multiple actuators dynamic coupling kinematic transformations model-basedcompensation
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Seismic performance evaluation of VCFPB isolated storage tank using real-time hybrid simulation 被引量:3
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作者 Hong Yue Tang Zhenyun +1 位作者 Li Zhenbao Du Xiuli 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2022年第2期501-515,共15页
Variable curvature friction pendulum bearings(VCFPB)effectively reduce the dynamic response of storage tanks induced by earthquakes.Shaking table testing is used to assess the seismic performance of VCFPB isolated sto... Variable curvature friction pendulum bearings(VCFPB)effectively reduce the dynamic response of storage tanks induced by earthquakes.Shaking table testing is used to assess the seismic performance of VCFPB isolated storage tanks.However,the vertical pressure and friction coefficient of the scaled VCFPB in the shaking table tests cannot match the equivalent values of these parameters in the prototype.To avoid this drawback,a real-time hybrid simulation(RTHS)test was developed.Using RTHS testing,a 1/8 scaled tank isolated by VCFPB was tested.The experimental results showed that the displacement dynamic magnification factor of VCFPB,peak reduction factors of the acceleration,shear force,and overturning moment at bottom of the tank,were negative exponential functions of the ratio of peak ground acceleration(PGA)and friction coefficient.The peak reduction factors of displacement,acceleration,force and overturning moment,which were obtained from the experimental results,are compared with those calculated by the Housner model.It can be concluded that the Housner model is applicable in estimation of the acceleration,shear force,and overturning moment of liquid storage tank,but not for the sliding displacement of VCFPBs. 展开更多
关键词 liquid storage tank base isolation variable curvature friction pendulum bearing seismic performance real-time hybrid simulation test
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Simulation of large-scale numerical substructure in real-time dynamic hybrid testing 被引量:7
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作者 Zhu Fei Wang Jinting +2 位作者 Jin Feng Zhou Mengxia Gui Yao 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2014年第4期599-609,共11页
A solution scheme is proposed in this paper for an existing RTDHT system to simulate large-scale finite element (FE) numerical substructures. The analysis of the FE numerical substructure is split into response anal... A solution scheme is proposed in this paper for an existing RTDHT system to simulate large-scale finite element (FE) numerical substructures. The analysis of the FE numerical substructure is split into response analysis and signal generation tasks, and executed in two different target computers in real-time. One target computer implements the response analysis task, wherein a large time-step is used to solve the FE substructure, and another target computer implements the signal generation task, wherein an interpolation program is used to generate control signals in a small time-step to meet the input demand of the controller. By using this strategy, the scale of the FE numerical substructure simulation may be increased significantly. The proposed scheme is initially verified by two FE numerical substructure models with 98 and 1240 degrees of freedom (DOFs). Thereafter, RTDHTs of a single frame-foundation structure are implemented where the foundation, considered as the numerical substructure, is simulated by the FE model with 1240 DOFs. Good agreements between the results of the RTDHT and those from the FE analysis in ABAQUS are obtained. 展开更多
关键词 real-time dynamic hybrid testing large-scale numerical substructure control signal generation finite element simulation
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Analysis of actuator delay and its effect on uncertainty quantification for real-time hybrid simulation 被引量:2
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作者 Cheng Chen Weijie Xu +1 位作者 Tong Guo Kai Chen 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2017年第4期713-725,共13页
Uncertainties in structure properties can result in different responses in hybrid simulations. Quantification of the effect of these tmcertainties would enable researchers to estimate the variances of structural respo... Uncertainties in structure properties can result in different responses in hybrid simulations. Quantification of the effect of these tmcertainties would enable researchers to estimate the variances of structural responses observed from experiments. This poses challenges for real-time hybrid simulation (RTHS) due to the existence of actuator delay. Polynomial chaos expansion (PCE) projects the model outputs on a basis of orthogonal stochastic polynomials to account for influences of model uncertainties. In this paper, PCE is utilized to evaluate effect of actuator delay on the maximum displacement from real-time hybrid simulation of a single degree of freedom (SDOF) structure when accounting for uncertainties in structural properties. The PCE is first applied for RTHS without delay to determine the order of PCE, the number of sample points as well as the method for coefficients calculation. The PCE is then applied to RTHS with actuator delay. The mean, variance and Sobol indices are compared and discussed to evaluate the effects of actuator delay on uncertainty quantification for RTHS. Results show that the mean and the variance of the maximum displacement increase linearly and exponentially with respect to actuator delay, respectively. Sensitivity analysis through Sobol indices also indicates the influence of the single random variable decreases while the coupling effect increases with the increase of actuator delay. 展开更多
关键词 real-time hybrid simulation actuator delay polynomial chaos expansion delay differential equation uncertainty quantification
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Real-time hybrid simulation for structural control performance assessment 被引量:2
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作者 Juan E Carrion BF Spencer Jr Brian M Phillips 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2009年第4期481-492,共12页
Real-time hybrid simulation is an attractive method to evaluate the response of structures under earthquake loads. The method is a variation of the pseudodynamic testing technique in which the experiment is executed i... Real-time hybrid simulation is an attractive method to evaluate the response of structures under earthquake loads. The method is a variation of the pseudodynamic testing technique in which the experiment is executed in real time, thus allowing investigation of structural systems with rate-dependent components. Real-time hybrid simulation is challenging because it requires performance of all calculations, application of displacements, and acquisition of measured forces, within a very small increment of time. Furthermore, unless appropriate compensation for actuator dynamics is implemented, stability problems are likely to occur during the experiment. This paper presents an approach for real-time hybrid simulation in which compensation for actuator dynamics is implemented using a model-based feedforward compensator. The method is used to evaluate the response of a semi-active control of a structure employing an MR damper. Experimental results show good agreement with the predicted responses, demonstrating the effectiveness of the method for structural control performance assessment. 展开更多
关键词 real-time hybrid simulation MR damper semi-active control actuator dynamics
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Real-time hybrid simulation of structures equipped with viscoelastic-plastic dampers using a user-programmable computational platform 被引量:2
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作者 Jack Wen Wei Guo Ali Ashasi-Sorkhabi +1 位作者 Oya Mercan Constantin Christopoulos 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2017年第4期693-711,共19页
A user-programmable computational/control platform was developed at the University of Toronto that offers real-time hybrid simulation (RTHS) capabilities. The platform was verified previously using several linear ph... A user-programmable computational/control platform was developed at the University of Toronto that offers real-time hybrid simulation (RTHS) capabilities. The platform was verified previously using several linear physical substructures. The study presented in this paper is focused on further validating the RTHS platform using a nonlinear viscoelastic-plastic damper that has displacement, frequency and temperature-dependent properties. The validation study includes damper component characterization tests, as well as RTHS of a series of single-degree-of-freedom (SDOF) systems equipped with viscoelastic-plastic dampers that represent different structural designs. From the component characterization tests, it was found that for a wide range of excitation frequencies and friction slip loads, the tracking errors are comparable to the errors in RTHS of linear spring systems. The hybrid SDOF results are compared to an independently validated thermal- mechanical viscoelastic model to further validate the ability for the platform to test nonlinear systems. After the validation, as an application study, nonlinear SDOF hybrid tests were used to develop performance spectra to predict the response of structures equipped with damping systems that are more challenging to model analytically. The use of the experimental performance spectra is illustrated by comparing the predicted response to the hybrid test response of 2DOF systems equipped with viscoelastic-plastic dampers. 展开更多
关键词 real-time hybrid simulation user-programmable computational/control platform supplemental dampers performance spectra
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Theoretical and experimental studies on critical time delay of multi-DOF real-time hybrid simulation 被引量:2
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作者 Lu Liqiao Wang Jinting +1 位作者 Ding Hao Zhu Fei 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2022年第1期117-134,共18页
This paper aims to investigate the critical stability of a multi-degree-of-freedom(multi-DOF)real-time hybrid simulation(RTHS).First,the critical time-delay analysis models are developed using the continuous-and discr... This paper aims to investigate the critical stability of a multi-degree-of-freedom(multi-DOF)real-time hybrid simulation(RTHS).First,the critical time-delay analysis models are developed using the continuous-and discrete-time root locus(RL)techniques,respectively.A bilinear transform is introduced into the first-order Padéapproximation while conducting the discrete RL analysis.Based on this technique,the time delay can be explicitly used as the gain factor and thus the instability mechanism of the multi-DOF RTHS system can be analyzed.Subsequently,the critical time delays calculated by the continuous-and discrete-time RL techniques,respectively,are compared for a 2-DOF RTHS system.It is shown that assuming the RTHS system to be a continuous-time system will result in overestimating the critical time delay.Finally,theoretically calculated critical delays are demonstrated and validated by numerical simulation and a set of RTHS experiments.Parametric analysis provides a glimpse of the effects of time step,frequency and damping ratio in a performing partitioning scheme.The constructed analysis model proves to be useful for evaluating the critical time delay to predict stability and performance,therefore facilitating successful RTHS. 展开更多
关键词 real-time hybrid simulation root locus critical time delay delay-dependent stability
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Control performance comparison between tuned liquid damper and tuned liquid column damper using real-time hybrid simulation 被引量:4
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作者 Zhu Fei Wang Jinting +1 位作者 Jin Feng Lu Liqiao 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2019年第3期695-701,共7页
Tuned liquid damper (TLD) and tuned liquid column damper (TLCD) are two types of passive control devices that are widely used in structural control. In this study, a real-time hybrid simulation (RTHS) technique is emp... Tuned liquid damper (TLD) and tuned liquid column damper (TLCD) are two types of passive control devices that are widely used in structural control. In this study, a real-time hybrid simulation (RTHS) technique is employed to investigate the diff erence in control performance between TLD and TLCD. A series of RTHSs is presented with the premise of the same liquid length, mass ratio, and structural parameters. Herein, TLD and TLCD are physically experimented, and controlled structures are numerically simulated. Then, parametric studies are performed to further evaluate the diff erent performance between TLD and TLCD. Experimental results demonstrate that TLD is more eff ective than TLCD under diff erent amplitude excitations. 展开更多
关键词 tuned LIQUID DAMPER tuned LIQUID COLUMN DAMPER real-time hybrid simulation CONTROL effi ciency STRUCTURAL CONTROL PARAMETRIC study
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Restoring force correction based on online discrete tangent stiffness estimation method for real-time hybrid simulation 被引量:2
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作者 Huang Liang Guo Tong +1 位作者 Chen Cheng Chen Menghui 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第4期805-820,共16页
In real-time hybrid simulation(RTHS), it is difficult if not impossible to completely erase the error in restoring force due to actuator response delay using existing displacement-based compensation methods. This pa... In real-time hybrid simulation(RTHS), it is difficult if not impossible to completely erase the error in restoring force due to actuator response delay using existing displacement-based compensation methods. This paper proposes a new force correction method based on online discrete tangent stiffness estimation(online DTSE) to provide accurate online estimation of the instantaneous stiffness of the physical substructure. Following the discrete curve parameter recognition theory, the online DTSE method estimates the instantaneous stiffness mainly through adaptively building a fuzzy segment with the latest measurements, constructing several strict bounding lines of the segment and calculating the slope of the strict bounding lines, which significantly improves the calculation efficiency and accuracy for the instantaneous stiffness estimation. The results of both computational simulation and real-time hybrid simulation show that:(1) the online DTSE method has high calculation efficiency, of which the relatively short computation time will not interrupt RTHS; and(2) the online DTSE method provides better estimation for the instantaneous stiffness, compared with other existing estimation methods. Due to the quick and accurate estimation of instantaneous stiffness, the online DTSE method therefore provides a promising technique to correct restoring forces in RTHS. 展开更多
关键词 online discrete tangent stiffness estimation restoring force correction fuzzy segment parameter updating real-time hybrid simulation
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Comparison of delay compensation methods for real-time hybrid simulation using frequency-domain evaluation index 被引量:2
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作者 Xu Weijie Guo Tong Chen Cheng 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2016年第1期129-143,共15页
The delay compensation method plays an essential role in maintaining the stability and achieving accurate real-time hybrid simulation results. The effectiveness of various compensation methods in different test scenar... The delay compensation method plays an essential role in maintaining the stability and achieving accurate real-time hybrid simulation results. The effectiveness of various compensation methods in different test scenarios, however, needs to be quantitatively evaluated. In this study, four compensation methods (i.e., the polynomial extrapolation, the linear acceleration extrapolation, the inverse compensation and the adaptive inverse compensation) are selected and compared experimentally using a frequency evaluation index (FEI) method. The effectiveness of the FEI method is first verified through comparison with the discrete transfer fimction approach for compensation methods assuming constant delay. Incomparable advantage is further demonstrated for the FEI method when applied to adaptive compensation methods, where the discrete transfer function approach is difficult to implement. Both numerical simulation and laboratory tests with predefined displacements are conducted using sinusoidal signals and random signals as inputs. Findings from numerical simulation and experimental results demonstrate that the FEI method is an efficient and effective approach to compare the performance of different compensation methods, especially for those requiring adaptation of compensation parameters. 展开更多
关键词 real-time hybrid simulation frequency domain evaluation index delay compensation methods
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Real-Time Hybrid Simulation of Seismically Isolated Structures with Full-Scale Bearings and Large Computational Models 被引量:3
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作者 Alireza Sarebanha Andreas H.Schellenberg +2 位作者 Matthew J.Schoettler Gilberto Mosqueda Stephen A.Mahin 《Computer Modeling in Engineering & Sciences》 SCIE EI 2019年第9期693-717,共25页
Hybrid simulation can be a cost effective approach for dynamic testing of structural components at full scale while capturing the system level response through interactions with a numerical model.The dynamic response ... Hybrid simulation can be a cost effective approach for dynamic testing of structural components at full scale while capturing the system level response through interactions with a numerical model.The dynamic response of a seismically isolated structure depends on the combined characteristics of the ground motion,bearings,and superstructure.Therefore,dynamic full-scale system level tests of isolated structures under realistic dynamic loading conditions are desirable towards a holistic validation of this earthquake protection strategy.Moreover,bearing properties and their ultimate behavior have been shown to be highly dependent on rate-of-loading and scale size effects,especially under extreme loading conditions.Few laboratory facilities can test full-scale seismic isolation bearings under prescribed displacement and/or loading protocols.The adaptation of a full-scale bearing test machine for the implementation of real-time hybrid simulation is presented here with a focus on the challenges encountered in attaining reliable simulation results for large scale dynamic tests.These advanced real-time hybrid simulations of large and complex hybrid models with several thousands of degrees of freedom are some of the first to use high performance parallel computing to rapidly execute the numerical analyses.Challenges in the experimental setup included measured forces contaminated by delay and other systematic control errors in applying desired displacements.Friction and inertial forces generated by the large-scale loading apparatus can affect the accuracy of measured force feedbacks.Reliable results from real-time hybrid simulation requires implementation of compensation algorithms and correction of these various sources of errors.Overall,this research program confirms that real-time hybrid simulation is a viable testing method to experimentally assess the behavior of full-scale isolators while capturing interactions with the numerical models of the superstructure to evaluate system level and in-structure response. 展开更多
关键词 real-time hybrid simulation SEISMIC ISOLATION PARALLEL processing full SCALE BEARING experimental testing
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Efficiency analysis of numerical integrations for finite element substructure in real-time hybrid simulation 被引量:5
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作者 Wang Jinting Lu Liqiao Zhu Fei 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第1期73-86,共14页
Finite element(FE) is a powerful tool and has been applied by investigators to real-time hybrid simulations(RTHSs). This study focuses on the computational efficiency, including the computational time and accuracy... Finite element(FE) is a powerful tool and has been applied by investigators to real-time hybrid simulations(RTHSs). This study focuses on the computational efficiency, including the computational time and accuracy, of numerical integrations in solving FE numerical substructure in RTHSs. First, sparse matrix storage schemes are adopted to decrease the computational time of FE numerical substructure. In this way, the task execution time(TET) decreases such that the scale of the numerical substructure model increases. Subsequently, several commonly used explicit numerical integration algorithms, including the central difference method(CDM), the Newmark explicit method, the Chang method and the Gui-λ method, are comprehensively compared to evaluate their computational time in solving FE numerical substructure. CDM is better than the other explicit integration algorithms when the damping matrix is diagonal, while the Gui-λ(λ = 4) method is advantageous when the damping matrix is non-diagonal. Finally, the effect of time delay on the computational accuracy of RTHSs is investigated by simulating structure-foundation systems. Simulation results show that the influences of time delay on the displacement response become obvious with the mass ratio increasing, and delay compensation methods may reduce the relative error of the displacement peak value to less than 5% even under the large time-step and large time delay. 展开更多
关键词 real-time hybrid simulation computational efficiency numerical integration storage optimization time delay
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A deep reinforcement learning approach to gasoline blending real-time optimization under uncertainty
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作者 Zhiwei Zhu Minglei Yang +3 位作者 Wangli He Renchu He Yunmeng Zhao Feng Qian 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2024年第7期183-192,共10页
The gasoline inline blending process has widely used real-time optimization techniques to achieve optimization objectives,such as minimizing the cost of production.However,the effectiveness of real-time optimization i... The gasoline inline blending process has widely used real-time optimization techniques to achieve optimization objectives,such as minimizing the cost of production.However,the effectiveness of real-time optimization in gasoline blending relies on accurate blending models and is challenged by stochastic disturbances.Thus,we propose a real-time optimization algorithm based on the soft actor-critic(SAC)deep reinforcement learning strategy to optimize gasoline blending without relying on a single blending model and to be robust against disturbances.Our approach constructs the environment using nonlinear blending models and feedstocks with disturbances.The algorithm incorporates the Lagrange multiplier and path constraints in reward design to manage sparse product constraints.Carefully abstracted states facilitate algorithm convergence,and the normalized action vector in each optimization period allows the agent to generalize to some extent across different target production scenarios.Through these well-designed components,the algorithm based on the SAC outperforms real-time optimization methods based on either nonlinear or linear programming.It even demonstrates comparable performance with the time-horizon based real-time optimization method,which requires knowledge of uncertainty models,confirming its capability to handle uncertainty without accurate models.Our simulation illustrates a promising approach to free real-time optimization of the gasoline blending process from uncertainty models that are difficult to acquire in practice. 展开更多
关键词 Deep reinforcement learning Gasoline blending real-time optimization PETROLEUM Computer simulation Neural networks
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Combined hybrid energy storage system and transmission grid model for peak shaving based on time series operation simulation 被引量:1
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作者 Mingkui Wei Yiyu Wen +3 位作者 Qiu Meng Shunwei Zheng Yuyang Luo Kai Liao 《Global Energy Interconnection》 EI CAS CSCD 2023年第2期154-165,共12页
This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure o... This study proposes a combined hybrid energy storage system(HESS) and transmission grid(TG) model, and a corresponding time series operation simulation(TSOS) model is established to relieve the peak-shaving pressure of power systems under the integration of renewable energy. First, a linear model for the optimal operation of the HESS is established, which considers the different power-efficiency characteristics of the pumped storage system, electrochemical storage system, and a new type of liquid compressed air energy storage. Second, a TSOS simulation model for peak shaving is built to maximize the power entering the grid from the wind farms and HESS. Based on the proposed model, this study considers the transmission capacity of a TG. By adding the power-flow constraints of the TG, a TSOS-based HESS and TG combination model for peak shaving is established. Finally, the improved IEEE-39 and IEEE-118 bus systems were considered as examples to verify the effectiveness and feasibility of the proposed model. 展开更多
关键词 Peak shaving hybrid energy storage system Combined energy storage and transmission grid model Time series operation simulation
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Dynamic phasor-based hybrid simulation for multi-inverter grid-connected system
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作者 Peng Yang Qian Li +2 位作者 Junyu Zhao Juanjuan Lu Yunfei Xu 《Global Energy Interconnection》 EI CAS CSCD 2023年第2期197-204,共8页
To realize the efficient transient simulation of a grid-connected power generation system based on multiple inverters, this paper proposes a hybrid simulation method integrating the models of electromagnetic transient... To realize the efficient transient simulation of a grid-connected power generation system based on multiple inverters, this paper proposes a hybrid simulation method integrating the models of electromagnetic transient and dynamic phasors. Based on a demonstration of the concepts and properties of dynamic phasors, the models of single-phase and three-phase inverters described by dynamic phasors are established first. Considering the numerical compatibility problem between dynamic phasors and instantaneous values, an interface scheme between dynamic phasors and instantaneous values is designed, and the efficiency and precision differences of various transformation methods are compared in detail.Finally, by utilizing MATLAB/Simulink, a hybrid simulation platform of a multi-inverter grid-connected system is built, and the efficiency and accuracy of the hybrid simulation are validated via comparison with the full electromagnetic transient simulation. 展开更多
关键词 Multi-inverter grid-connected system Electromagnetic transient Dynamic phasor hybrid simulation
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Broadband ground motion simulation using a hybrid approach of the May 21, 2021 M7.4 earthquake in Maduo, Qinghai, China
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作者 Yijun Liu Xiaofen Zhao +4 位作者 Zengping Wen Jie Liu Bo Chen Chunyao Bu Chao Xu 《Earthquake Science》 2023年第3期175-199,共25页
In this study,the broadband ground motions of the 2021 M7.4 Maduo earthquake were simulated to overcome the scarcity of ground motion recordings and the low resolution of macroseismic intensity map in sparsely populat... In this study,the broadband ground motions of the 2021 M7.4 Maduo earthquake were simulated to overcome the scarcity of ground motion recordings and the low resolution of macroseismic intensity map in sparsely populated high-altitude regions.The simulation was conducted with a hybrid methodology,combining a stochastic high-frequency simulation with a low-frequency ground motion simulation,from the regional 1-D velocity structure model and the Wang WM et al.(2022)source rupture model,respectively.We found that the three-component waveforms simulated for specific stations matched the waveforms recorded at those stations,in terms of amplitude,duration,and frequency content.The validation results demonstrate the ability of the hybrid simulation method to reproduce the main characteristics of the observed ground motions for the 2021 Maduo earthquake over a broad frequency range.Our simulations suggest that the official map of macroseismic intensity tends to overestimate shaking by one intensity unit.Comparisons of simulations with empirical ground motion models indicate generally good consistency between the simulated and empirically predicted intensity measures.The high-frequency components of ground motions were found to be more prominent,while the low-frequency components were not,which is unexpected for large earthquakes.Our simulations provide valuable insight into the effects of source complexity on the level and variability of the resulting ground motions.The acceleration and velocity time histories and corresponding response spectra were provided for selected representative sites where no records were available.The simulated results have important implications for evaluating the performance of engineering structures in the epicentral regions of this earthquake and for estimating seismic hazards in the Tibetan regions where no strong ground motion records are available for large earthquakes. 展开更多
关键词 Maduo earthquake hybrid broadband simulation source rupture model path model macroseismic intensity
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