The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructi...The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructive particle damping-phononic crystal vibration isolator is proposed herein,which uses the particle damping vibration absorption technology and bandgap vibration control theory.The vibration reduction performance of the NOPD-PCVI was analyzed from the perspective of vibration control.The paper explores the structure-borne noise reduction performance of the NOPD-PCVIs installed on different bridge structures under varying service conditions encountered in practical engineering applications.The load transferred to the bridge is obtained from a coupled train-FST-bridge analytical model considering the different structural parameters of bridges.The vibration responses are obtained using the finite element method,while the structural noise radiation is simulated using the frequency-domain boundary element method.Using the particle swarm optimization algorithm,the parameters of the NOPD-PCVI are optimized so that its frequency bandgap matches the dominant bridge structural noise frequency range.The noise reduction performance of the NOPD-PCVIs is compared to the steel-spring isolation under different service conditions.展开更多
Research on particulate characteristics has been an important frontier in physics and chemistry during the past decades. It has however been mostly focused on granular materials with short-range interactions. In this ...Research on particulate characteristics has been an important frontier in physics and chemistry during the past decades. It has however been mostly focused on granular materials with short-range interactions. In this work, it was found that the power law of particle size distribution applied to the long-range interacting system of floating dust in air, from which we deduced that self-organized criticality might hold for floating dust just as granular materials with short-range interactions. This feature may reveal underlying kinetic mechanisms, important in dispersed particle systems. In industry, power law of size distribution of dispersed particles can be used to investigate the change of dust size, and the power law parameter could be taken as an important index for dust separation.展开更多
The service capacity of urban public open spaces is an important indicator of the justness and soundness of the allocation of public space resources,such as parks and green spaces,in the process of urban development.I...The service capacity of urban public open spaces is an important indicator of the justness and soundness of the allocation of public space resources,such as parks and green spaces,in the process of urban development.Improving the service capacity of urban public open spaces is conductive to healthy,sustainable urban development.In this study,taking Shengyang City,China as a case study,a Gaussian-based two-step floating catchment area method(2 SFCA)is used to calculate an accessibility index and identify residential areas with a poor accessibility to urban public open spaces.Then,a particle swarm algorithm(PSA)is used to optimize the locations of new open space developments.Finally,the optimization results are verified using the analytic network process(ANP).The results show that the service capacity of public open spaces in the center of Shenyang City(covering six districts)is relatively low and exhibits an uneven spatial distribution.In the service scope of the existing urban public open spaces,the accessibility for 48.6%of the residential estates is moderately poor or poor.The layout is optimized when the number of optimization points is set to 8.These points are mainly located in old town areas such as the Tiexi,Huanggu,and Dadong districts.The optimization increases the green space area accessible by motor vehicles(60 min),bicycles(60 min),and walking(30 min)by 4.67%,5.38%,and 8.03%of the study area,respectively.Finally,green space planning recommendations are offered from two perspectives:spatial layout and transport system optimization.展开更多
基金Project(51978585)supported by the National Natural Science Foundation,ChinaProject(2022YFB2603404)supported by the National Key Research and Development Program,China+1 种基金Project(U1734207)supported by the High-speed Rail Joint Fund Key Projects of Basic Research,ChinaProject(2023NSFSC1975)supported by the Sichuan Nature and Science Foundation Innovation Research Group Project,China。
文摘The problems associated with vibrations of viaducts and low-frequency structural noise radiation caused by train excitation continue to increase in importance.A new floating-slab track vibration isolator-non-obstructive particle damping-phononic crystal vibration isolator is proposed herein,which uses the particle damping vibration absorption technology and bandgap vibration control theory.The vibration reduction performance of the NOPD-PCVI was analyzed from the perspective of vibration control.The paper explores the structure-borne noise reduction performance of the NOPD-PCVIs installed on different bridge structures under varying service conditions encountered in practical engineering applications.The load transferred to the bridge is obtained from a coupled train-FST-bridge analytical model considering the different structural parameters of bridges.The vibration responses are obtained using the finite element method,while the structural noise radiation is simulated using the frequency-domain boundary element method.Using the particle swarm optimization algorithm,the parameters of the NOPD-PCVI are optimized so that its frequency bandgap matches the dominant bridge structural noise frequency range.The noise reduction performance of the NOPD-PCVIs is compared to the steel-spring isolation under different service conditions.
基金The present project is currently sponsored by the National Natural Science Foundation of China through Contract#50406018the Scientific Research Foundation for Returned Overseas Chinese Scholars.
文摘Research on particulate characteristics has been an important frontier in physics and chemistry during the past decades. It has however been mostly focused on granular materials with short-range interactions. In this work, it was found that the power law of particle size distribution applied to the long-range interacting system of floating dust in air, from which we deduced that self-organized criticality might hold for floating dust just as granular materials with short-range interactions. This feature may reveal underlying kinetic mechanisms, important in dispersed particle systems. In industry, power law of size distribution of dispersed particles can be used to investigate the change of dust size, and the power law parameter could be taken as an important index for dust separation.
基金Under the auspices of the China National R&D Program(No.2017YFC0505704)National Natural Science Foundation of China(No.32101325)+1 种基金Fundamental Research Funds for the Central Universities of China(No.N2011005)Student Innovation Training Program of Northeastern University of China(No.201299)。
文摘The service capacity of urban public open spaces is an important indicator of the justness and soundness of the allocation of public space resources,such as parks and green spaces,in the process of urban development.Improving the service capacity of urban public open spaces is conductive to healthy,sustainable urban development.In this study,taking Shengyang City,China as a case study,a Gaussian-based two-step floating catchment area method(2 SFCA)is used to calculate an accessibility index and identify residential areas with a poor accessibility to urban public open spaces.Then,a particle swarm algorithm(PSA)is used to optimize the locations of new open space developments.Finally,the optimization results are verified using the analytic network process(ANP).The results show that the service capacity of public open spaces in the center of Shenyang City(covering six districts)is relatively low and exhibits an uneven spatial distribution.In the service scope of the existing urban public open spaces,the accessibility for 48.6%of the residential estates is moderately poor or poor.The layout is optimized when the number of optimization points is set to 8.These points are mainly located in old town areas such as the Tiexi,Huanggu,and Dadong districts.The optimization increases the green space area accessible by motor vehicles(60 min),bicycles(60 min),and walking(30 min)by 4.67%,5.38%,and 8.03%of the study area,respectively.Finally,green space planning recommendations are offered from two perspectives:spatial layout and transport system optimization.
