In this paper, a probabilistic distribution of fatigue strength as a function of fatigue life is discussed. The transformation method between fatigue life and fatigue strength developed in the past by other methods ...In this paper, a probabilistic distribution of fatigue strength as a function of fatigue life is discussed. The transformation method between fatigue life and fatigue strength developed in the past by other methods did not deal with the fact that the scatter factor of fatigue life increases at a low stress level. A modified model of fatigue strength distribution based on the fatigue scatter investigation is presented in this paper. The results of the statistical inferences from a large sample fatigue test indicate that the proposed model can be accepted at a 10% level of significance.展开更多
This paper modifies the weighted probabilistic cellular automaton model （Li X L, Kuang H, Song T, et al 2008 Chin. Phys. B 17 2366） which considered a diversity of traffic behaviors under real traffic situations ind...This paper modifies the weighted probabilistic cellular automaton model （Li X L, Kuang H, Song T, et al 2008 Chin. Phys. B 17 2366） which considered a diversity of traffic behaviors under real traffic situations induced by various driving characters and habits. In the new model, the effects of the velocity at the last time step and drivers＇ desire for acceleration are taken into account. The fundamental diagram, spatial-temporal diagram, and the time series of one-minute data are analyzed. The results show that this model reproduces synchronized flow. Finally, it simulates the on-ramp system with the proposed model. Some characteristics including the phase diagram are studied.展开更多
Higher-order multiscale structures are proposed to predict the effective elastic properties of 3-phase particle reinforced composites by considering the probabilistic spherical particles spatial distribution,the parti...Higher-order multiscale structures are proposed to predict the effective elastic properties of 3-phase particle reinforced composites by considering the probabilistic spherical particles spatial distribution,the particle interactions,and utilizing homogenization with ensemble volume average approach.The matrix material,spherical particles with radius a1,and spherical particles with radius a2,are denoted as the 0th phase,the 1st phase,and the 2nd phase,respectively.Particularly,the two inhomogeneity phases are different particle sizes and the same elastic material properties.Improved higher-order(in ratio of spherical particle sizes to the distance between the centers of spherical particles)bounds on effective elastic properties of 3-phase particle reinforced proposed Formulation II and Formulation I derive composites.As a special case,i.e.,particle size of the 1st phase is the same as that of the 2nd phase,the proposed formulations reduce to 2-phase formulas.Our theoretical predictions demonstrate excellent agreement with selected experimental data.In addition,several numerical examples are presented to demonstrate the competence of the proposed frameworks.展开更多
An optimal preventive-corrective control model for static voltage stability under multiple N-1 contingencies considering the wind power uncertainty is established in this paper.The objective is to minimize the control...An optimal preventive-corrective control model for static voltage stability under multiple N-1 contingencies considering the wind power uncertainty is established in this paper.The objective is to minimize the control variable adjustment cost including the load shedding cost of each contingency.The chance constraints of the static voltage stability margins(SvSMs)in the normal operation state and after each N-1 contingency are included.The approximate functions between the probability density functions(PDFs)of SVSMs and load shedding quantity with respect to preventive control variables are obtained to transform the expectation of load shedding quantity and the SvSM chance constraints into deterministic expressions.An approximate sequential convex quadratically constrained quadratic programming iteration method is proposed to solve the optimal control model.In each iteration,the approximate expressions and range are determined by the generated data samples.Moreover,a fast approximation calculation method of second-order matrices is proposed.By the naive Bayes classifier,the most severe N-1 contingencies are selected to replace all the contingencies to be added to the optimization model to improve the computational efficiency.Case studies on the IEEE-39 bus system and an actual provincial power grid demonstrate the effectiveness and efficiency of the proposed method.展开更多
With the technical development of wind power forecasting,making wind power generation schedule in power systems become an inevitable tendency.This paper proposes a new dispatch method for wind farm(WF)cluster by consi...With the technical development of wind power forecasting,making wind power generation schedule in power systems become an inevitable tendency.This paper proposes a new dispatch method for wind farm(WF)cluster by considering wind power forecasting errors.A probability distribution model of wind power forecasting errors and a mathematic expectation of the power shortage caused by forecasting errors are established.Then,the total mathematic expectation of power shortage from all WFs is minimized.Case study with respect to power dispatch in a WF cluster is conducted using forecasting and actual wind power data within 30 days from sites located at Gansu Province.Compared with the variable proportion method,the power shortage of the WF cluster caused by wind power forecasting errors is reduced.Along with the increment of wind power integrated into power systems,the method positively influences future wind power operation.展开更多
文摘In this paper, a probabilistic distribution of fatigue strength as a function of fatigue life is discussed. The transformation method between fatigue life and fatigue strength developed in the past by other methods did not deal with the fact that the scatter factor of fatigue life increases at a low stress level. A modified model of fatigue strength distribution based on the fatigue scatter investigation is presented in this paper. The results of the statistical inferences from a large sample fatigue test indicate that the proposed model can be accepted at a 10% level of significance.
基金supported by the State Key Development Program for Basic Research of China (Grant No 2006CB705500)the National Natural Science Foundation of China (Grant Nos 70631001,70501004 and 70701004)Program for New Century Excellent Talents in University (Grant No CET-07-0057)
文摘This paper modifies the weighted probabilistic cellular automaton model （Li X L, Kuang H, Song T, et al 2008 Chin. Phys. B 17 2366） which considered a diversity of traffic behaviors under real traffic situations induced by various driving characters and habits. In the new model, the effects of the velocity at the last time step and drivers＇ desire for acceleration are taken into account. The fundamental diagram, spatial-temporal diagram, and the time series of one-minute data are analyzed. The results show that this model reproduces synchronized flow. Finally, it simulates the on-ramp system with the proposed model. Some characteristics including the phase diagram are studied.
基金This work was in part sponsored by the 2015-2016 California State University Long Beach Research,Scholarship and Creative Activity(RSCA)Award。
文摘Higher-order multiscale structures are proposed to predict the effective elastic properties of 3-phase particle reinforced composites by considering the probabilistic spherical particles spatial distribution,the particle interactions,and utilizing homogenization with ensemble volume average approach.The matrix material,spherical particles with radius a1,and spherical particles with radius a2,are denoted as the 0th phase,the 1st phase,and the 2nd phase,respectively.Particularly,the two inhomogeneity phases are different particle sizes and the same elastic material properties.Improved higher-order(in ratio of spherical particle sizes to the distance between the centers of spherical particles)bounds on effective elastic properties of 3-phase particle reinforced proposed Formulation II and Formulation I derive composites.As a special case,i.e.,particle size of the 1st phase is the same as that of the 2nd phase,the proposed formulations reduce to 2-phase formulas.Our theoretical predictions demonstrate excellent agreement with selected experimental data.In addition,several numerical examples are presented to demonstrate the competence of the proposed frameworks.
基金supported by the National Natural Science Foundation of China under Grant 51977080the Natural Science Foundation of Guangdong Province(2023A1515240075).
文摘An optimal preventive-corrective control model for static voltage stability under multiple N-1 contingencies considering the wind power uncertainty is established in this paper.The objective is to minimize the control variable adjustment cost including the load shedding cost of each contingency.The chance constraints of the static voltage stability margins(SvSMs)in the normal operation state and after each N-1 contingency are included.The approximate functions between the probability density functions(PDFs)of SVSMs and load shedding quantity with respect to preventive control variables are obtained to transform the expectation of load shedding quantity and the SvSM chance constraints into deterministic expressions.An approximate sequential convex quadratically constrained quadratic programming iteration method is proposed to solve the optimal control model.In each iteration,the approximate expressions and range are determined by the generated data samples.Moreover,a fast approximation calculation method of second-order matrices is proposed.By the naive Bayes classifier,the most severe N-1 contingencies are selected to replace all the contingencies to be added to the optimization model to improve the computational efficiency.Case studies on the IEEE-39 bus system and an actual provincial power grid demonstrate the effectiveness and efficiency of the proposed method.
基金This work was supported by the Nation High Technology R&D Program of China(No.2011AA05A104)funded by Ministry of Science and Technology,and the Key Technological Projects“Research on Integrated Supervisory and Control Technolo-gies of Wind Farm Containing Wind Power Prediction System”“Application and Research on the Key Techniques for Large-scale Grid Friendly Wind Farm”funded by State Grid Corporation of China。
文摘With the technical development of wind power forecasting,making wind power generation schedule in power systems become an inevitable tendency.This paper proposes a new dispatch method for wind farm(WF)cluster by considering wind power forecasting errors.A probability distribution model of wind power forecasting errors and a mathematic expectation of the power shortage caused by forecasting errors are established.Then,the total mathematic expectation of power shortage from all WFs is minimized.Case study with respect to power dispatch in a WF cluster is conducted using forecasting and actual wind power data within 30 days from sites located at Gansu Province.Compared with the variable proportion method,the power shortage of the WF cluster caused by wind power forecasting errors is reduced.Along with the increment of wind power integrated into power systems,the method positively influences future wind power operation.
