A linear response history analysis method is used to determine the influence of three factors:geometric incoherency,wave-passage,and local site characteristics on the response of lnulti-support structures subjected to...A linear response history analysis method is used to determine the influence of three factors:geometric incoherency,wave-passage,and local site characteristics on the response of lnulti-support structures subjected to differential ground motions.A one-span frame and a reduced model of a 24-span bridge,located in Las Vegas,Nevada are studied,in which the influence of each of the three factors and their combinations are analyzed.It is revealed that the incoherency of earthquake ground motion can have a dramatic influence on structural response by modifying the dynamics response to uniform excitation and inducing pseudo-static response,which does not exist in structures subjected to uniform excitation.The total response when all three sources of ground motion incoherency are included is generally larger than that of uniform excitation.展开更多
The design of aircraft hydraulic pipeline system is limited by many factors,such as the integrity of aviation structure or narrow installation space,so the limited clamp support position should be considered.This pape...The design of aircraft hydraulic pipeline system is limited by many factors,such as the integrity of aviation structure or narrow installation space,so the limited clamp support position should be considered.This paper studied the frequency adjustment and dynamic responses reduction of the multi-support pipeline system through experiment and numerical simulation.To avoid the resonance of pipeline system,we proposed two different optimization programs,one was to avoid aero-engine working range,and another was to avoid aircraft hydraulic pump pulsation range.An optimization method was introduced in this paper to obtain the optimal clamp position.The experiments were introduced to validate the optimization results,and the theoretical optimization results can agree well with the test.With regard to avoiding the aero-engine vibration frequency,the test results revealed that the first natural frequency was far from the aero-engine vibration frequency.And the dynamic frequency sweep results showed that no resonance occurred on the pipeline in the engine vibration frequency range after optimization.Additionally,with regard to avoiding the pump vibration frequency,the test results revealed that natural frequencies have been adjusted and far from the pump vibration frequency.And the dynamic frequency sweep results showed that pipeline under optimal clamp position cannot lead to resonance.The sensitivity analysis results revealed the changing relationships between different clamp position and natural frequency.This study can provide helpful guidance on the analysis and design of practical aircraft pipeline.展开更多
To achieve rational and precise seismic response predictions of large span spatial structures(LSSSs),the inherent non-uniformity and multidimensionality characteristics of earthquake ground motions should be properly ...To achieve rational and precise seismic response predictions of large span spatial structures(LSSSs),the inherent non-uniformity and multidimensionality characteristics of earthquake ground motions should be properly taken into consideration.However,due to the limitations of available earthquake stations to record seismic rotational components,the effects of rocking and torsional earthquake components are commonly neglected in the seismic analyses of LSSSs.In this study,a newly developed method to extract the rocking and torsion components at any point along the area of a deployed dense array from the translational earthquake recordings is applied to obtain the rotational seismic inputs for a LSSS.The numerical model of an actual LSSS,the Dalian International Conference Center(DICC),is developed to study the influences of multi-support and multidimensional excitations on the seismic responses of LSSSs.The numerical results reveal that the non-uniformity and multidimensionality of ground motion input can considerably affect the dynamic response of the DICC.The specific degree of influence on the overall and local structural displacements,deformations and forces are comprehensively investigated and discussed.展开更多
In this paper, a new spatial coherence model of seismic ground motions is proposed by a fitting procedure. The analytical expressions of modal combination （correlation） coefficients of structural response are develo...In this paper, a new spatial coherence model of seismic ground motions is proposed by a fitting procedure. The analytical expressions of modal combination （correlation） coefficients of structural response are developed for multi-support seismic excitations. The coefficients from both the numerical integration and analytical solutions are compared to verify the accuracy of the solutions. It is shown that the analytical expressions of numerical modal combination coefficients are of high accuracy. The results of random responses of an example bridge show that the analytical modal combination coefficients developed in this paper are accurate enough to meet the requirements needed in practice. In addition, the computational efficiency of the analytical solutions of the modal combination coefficients is demonstrated by the response computation of the example bridge. It is found that the time required for the structural response analysis by using the analytical modal combination coefficients is less than 1/20 of that using numerical integral methods.展开更多
The pseudo excitation method(PEM) has been improved into a more practical form,on which the analytic formulae of seismic response power spectral density(PSD) of simplified large-span structural models have been derive...The pseudo excitation method(PEM) has been improved into a more practical form,on which the analytic formulae of seismic response power spectral density(PSD) of simplified large-span structural models have been derived.The analytic formulae and numerical computing results of seismic response PSD have been derived to study the mechanism of multi-support excitation effects,such as the wave-passage effect and incoherence effect,for the seismic response of multiand large-span structures.By using a multi-span truss as an example,the influence of multi-support excitation effects on the seismic response of such structures is studied.展开更多
A practical suspen-dome project, Changzhou Gym roof, is adopted as an example and its transient analysis based on the multi-support excitations of the earthquake wave is carried out. Compared with the single support e...A practical suspen-dome project, Changzhou Gym roof, is adopted as an example and its transient analysis based on the multi-support excitations of the earthquake wave is carried out. Compared with the single support excitation, the position and value of the maximum stress under multi-support excitations both change and the amount of elements with obvious changes is large and more than 70% of the total. Moreover, when other terms are not changed, this influence will decrease as the span decreases, but increa...展开更多
The nonlinear analysis of pounding between bridge deck segments subjected to multi-support excitations and multi-dimensional earthquake motion was performed.A novel bottom rigid element(BRE)method of the current displ...The nonlinear analysis of pounding between bridge deck segments subjected to multi-support excitations and multi-dimensional earthquake motion was performed.A novel bottom rigid element(BRE)method of the current displacement input model for structural seismic analysis under the multi-support excitations was used to calculate structural dynamic response.In the analysis,pounding between adjacent deck segments was considered.The seismic response of a multi-span bridge subjected to the multi-support excitation,considering not only the traveling-wave effect and partial coherence effect,but also the seismic non-stationary characteristics of multi-support earthquake motion,was simulated using finite element method(FEM).Meanwhile,the seismic response of the bridge under uniform earthquake was also analyzed.Finally,comparative analysis was conducted and some calculation results were shown for pounding effect,under multi-dimensional and multi-support earthquake motion,when performing seismic response analysis of multi-span bridge.Compared with the case of uniform/multi-support/multi-support and multi-dimensional earthquake input,the maximum values of pounding force in the case of multi-support and multi-dimensional earthquake input increase by about 5 8 times;the absolute value of bottom moment and shear force of piers increase by about50%600%and 23.1%900%,respectively.A conclusion can be given that it is very necessary to consider the pounding effect under multi-dimensional and multi-support earthquake motion while performing seismic response analysis of multi-span bridge.展开更多
Kilns are the key equipment in the metallurgy,architectural and chemistry industry.It is the statically indeterminate system with over load,large torque and multi-support.The kiln move axis warp resulting in that the ...Kilns are the key equipment in the metallurgy,architectural and chemistry industry.It is the statically indeterminate system with over load,large torque and multi-support.The kiln move axis warp resulting in that the load distribution is asymmetry,cause many mechanical failure and safe accidents and the interruption of the produce,which bring a great losses.Treating the distribution of the kiln load and the complexity of the stiffness change,the all-purpose model and matrix,used to solve the variable-stiffness beam upon complex load,are established in this paper.The resultant force of kiln in vertical and horizontal direction is calculated.Accordingly,the liner formulas for calculating the supporting force of the support wheels are obtained,and the wheel supporting force also can be easily obtained based on each shell warp.This will provide theory conference for safety management and rational maintenance.展开更多
The precast segmental column(PSC)plays a vital role in both the design of new bridges and the rehabilitation of existing ones.Previous studies of PSCs have primarily focused on their individual seismic behavior.Howeve...The precast segmental column(PSC)plays a vital role in both the design of new bridges and the rehabilitation of existing ones.Previous studies of PSCs have primarily focused on their individual seismic behavior.However,research on the seismic performance of entire bridges supported by PSCs,particularly those incorporating soil-structure interaction(SSI),remains limited.Moreover,the amplification of earthquake waves as they propagate along the pile foundation to the surface,coupled with the coherency loss between earthquake motions at varying supports,may further impact the seismic responses of such bridges.This study systematically assesses the seismic performance of a PSC bridge(PSCB)supported by pile foundations considering the effects of SSI and depth-varying multi-support ground motions.Moreover,a benchmark bridge with the traditional monolithic column is also analyzed for comparison.The seismic fragility of bridges is calculated based on nonlinear time history analyses and joint probability density functions for both peak and residual responses.Parameter studies are conducted to reveal the influences of sSI,non-uniform excitation,and depth-varying earthquake loads on seismic performance assessments.This paper offers valuable insights for the reliable analysis of seismic response and fragility and the safety design of PSCB systems.展开更多
The vibration tests of Laoshan bicycle gymnasium for the Olympic Games are performed under multi-support excitations in order to verify the effectiveness of multi-support time history method. The excitation sources co...The vibration tests of Laoshan bicycle gymnasium for the Olympic Games are performed under multi-support excitations in order to verify the effectiveness of multi-support time history method. The excitation sources come from the impact forces acting on the ring beam of the reticulated structure, on the basis of which the records of motions of each excited point and corresponding structural vibration responses are all collected. The theoretical analytical model of the structure is further established and the structural dynamic responses are obtained subjected to the same excitation case via multi-support time history method. The calculation results are generally in agreement with those of the test in both time domain and frequency domain, which verify the effectiveness of multi-support time history method. The vibration test can also provide references for long-span structures under multi-support excitations.展开更多
人工智能(AI)作为引领新一轮科技革命的核心技术,已深度融入临床医学的各个环节。自20世纪50年代诞生以来,AI经历了从符号逻辑到深层神经网络的跨越式发展,目前已在疾病诊断、方案制订、药物研发及医院管理中展现出广阔的应用前景。国...人工智能(AI)作为引领新一轮科技革命的核心技术,已深度融入临床医学的各个环节。自20世纪50年代诞生以来,AI经历了从符号逻辑到深层神经网络的跨越式发展,目前已在疾病诊断、方案制订、药物研发及医院管理中展现出广阔的应用前景。国际监管方面,美国食品药品监督管理局(FDA)已建立并持续更新AI-Enabled Medical Device List,并对相关软件和器械实施风险分级与全生命周期监管。国内方面,中国在积极推进“AI+医疗卫生”行动、促进新技术临床转化的同时,监管部门亦同步加强制度建设,在医疗器械注册审评、AI医疗软件风险管理、数据安全与隐私保护等方面逐步完善规范要求,形成覆盖技术准入、应用实施与风险防控的监管体系,为AI技术在临床实践中的规范落地提供制度支撑。在上述国际与国内监管框架的共同推动下,AI技术正逐步应用于临床诊疗与公共卫生管理,在提升基层医疗服务能力、肿瘤早筛及流行病学管理等方面展现出重要应用前景。该文综述了AI在临床医学中的最新应用进展,涵盖计算机视觉与自然语言处理等技术基础,系统分析了其在实际应用中面临的数据隐私、算法透明度及法律责任界定等挑战,并强调AI医疗应用应坚持“以人为本”和“人类主导”原则,通过多中心验证与协同监管,推动精准医学的可持续发展。展开更多
基金the China Scholarship Council and the Teaching and Research Award Program for Outstanding Young Teachers (TRAPOYT) in Higher Education Institutions of MOE,PRC.
文摘A linear response history analysis method is used to determine the influence of three factors:geometric incoherency,wave-passage,and local site characteristics on the response of lnulti-support structures subjected to differential ground motions.A one-span frame and a reduced model of a 24-span bridge,located in Las Vegas,Nevada are studied,in which the influence of each of the three factors and their combinations are analyzed.It is revealed that the incoherency of earthquake ground motion can have a dramatic influence on structural response by modifying the dynamics response to uniform excitation and inducing pseudo-static response,which does not exist in structures subjected to uniform excitation.The total response when all three sources of ground motion incoherency are included is generally larger than that of uniform excitation.
基金Supported by National Natural Science Foundation of China(Grant No.51875460)Aviation Power Foundation(Grant No.6141B090320)Foundation of Innovation and Creation for Graduate Students in Northwestern Ploytechnical University(Grant No.ZZ2019124).
文摘The design of aircraft hydraulic pipeline system is limited by many factors,such as the integrity of aviation structure or narrow installation space,so the limited clamp support position should be considered.This paper studied the frequency adjustment and dynamic responses reduction of the multi-support pipeline system through experiment and numerical simulation.To avoid the resonance of pipeline system,we proposed two different optimization programs,one was to avoid aero-engine working range,and another was to avoid aircraft hydraulic pump pulsation range.An optimization method was introduced in this paper to obtain the optimal clamp position.The experiments were introduced to validate the optimization results,and the theoretical optimization results can agree well with the test.With regard to avoiding the aero-engine vibration frequency,the test results revealed that the first natural frequency was far from the aero-engine vibration frequency.And the dynamic frequency sweep results showed that no resonance occurred on the pipeline in the engine vibration frequency range after optimization.Additionally,with regard to avoiding the pump vibration frequency,the test results revealed that natural frequencies have been adjusted and far from the pump vibration frequency.And the dynamic frequency sweep results showed that pipeline under optimal clamp position cannot lead to resonance.The sensitivity analysis results revealed the changing relationships between different clamp position and natural frequency.This study can provide helpful guidance on the analysis and design of practical aircraft pipeline.
基金National Natural Science Foundation of China under Grant Nos.51738007,51808099the Fundamental Research Funds for the Central Universities under Grant No.DUT20RC(3)005。
文摘To achieve rational and precise seismic response predictions of large span spatial structures(LSSSs),the inherent non-uniformity and multidimensionality characteristics of earthquake ground motions should be properly taken into consideration.However,due to the limitations of available earthquake stations to record seismic rotational components,the effects of rocking and torsional earthquake components are commonly neglected in the seismic analyses of LSSSs.In this study,a newly developed method to extract the rocking and torsion components at any point along the area of a deployed dense array from the translational earthquake recordings is applied to obtain the rotational seismic inputs for a LSSS.The numerical model of an actual LSSS,the Dalian International Conference Center(DICC),is developed to study the influences of multi-support and multidimensional excitations on the seismic responses of LSSSs.The numerical results reveal that the non-uniformity and multidimensionality of ground motion input can considerably affect the dynamic response of the DICC.The specific degree of influence on the overall and local structural displacements,deformations and forces are comprehensively investigated and discussed.
基金National Natural Science Foundation of China Under Grant No. 50478112
文摘In this paper, a new spatial coherence model of seismic ground motions is proposed by a fitting procedure. The analytical expressions of modal combination （correlation） coefficients of structural response are developed for multi-support seismic excitations. The coefficients from both the numerical integration and analytical solutions are compared to verify the accuracy of the solutions. It is shown that the analytical expressions of numerical modal combination coefficients are of high accuracy. The results of random responses of an example bridge show that the analytical modal combination coefficients developed in this paper are accurate enough to meet the requirements needed in practice. In addition, the computational efficiency of the analytical solutions of the modal combination coefficients is demonstrated by the response computation of the example bridge. It is found that the time required for the structural response analysis by using the analytical modal combination coefficients is less than 1/20 of that using numerical integral methods.
基金National Natural Science Foundation of China under Grant No.51038006Specializes Research Fund for the Doctoral Program of Higher Education under Grant No.20090002110045
文摘The pseudo excitation method(PEM) has been improved into a more practical form,on which the analytic formulae of seismic response power spectral density(PSD) of simplified large-span structural models have been derived.The analytic formulae and numerical computing results of seismic response PSD have been derived to study the mechanism of multi-support excitation effects,such as the wave-passage effect and incoherence effect,for the seismic response of multiand large-span structures.By using a multi-span truss as an example,the influence of multi-support excitation effects on the seismic response of such structures is studied.
基金Supported by National Natural Science Foundation of China (No. 50778122)Program for New Century Excellent Talents in University (NCET)
文摘A practical suspen-dome project, Changzhou Gym roof, is adopted as an example and its transient analysis based on the multi-support excitations of the earthquake wave is carried out. Compared with the single support excitation, the position and value of the maximum stress under multi-support excitations both change and the amount of elements with obvious changes is large and more than 70% of the total. Moreover, when other terms are not changed, this influence will decrease as the span decreases, but increa...
基金Project(51078242)supported by the National Natural Science Foundation of China
文摘The nonlinear analysis of pounding between bridge deck segments subjected to multi-support excitations and multi-dimensional earthquake motion was performed.A novel bottom rigid element(BRE)method of the current displacement input model for structural seismic analysis under the multi-support excitations was used to calculate structural dynamic response.In the analysis,pounding between adjacent deck segments was considered.The seismic response of a multi-span bridge subjected to the multi-support excitation,considering not only the traveling-wave effect and partial coherence effect,but also the seismic non-stationary characteristics of multi-support earthquake motion,was simulated using finite element method(FEM).Meanwhile,the seismic response of the bridge under uniform earthquake was also analyzed.Finally,comparative analysis was conducted and some calculation results were shown for pounding effect,under multi-dimensional and multi-support earthquake motion,when performing seismic response analysis of multi-span bridge.Compared with the case of uniform/multi-support/multi-support and multi-dimensional earthquake input,the maximum values of pounding force in the case of multi-support and multi-dimensional earthquake input increase by about 5 8 times;the absolute value of bottom moment and shear force of piers increase by about50%600%and 23.1%900%,respectively.A conclusion can be given that it is very necessary to consider the pounding effect under multi-dimensional and multi-support earthquake motion while performing seismic response analysis of multi-span bridge.
基金Supported by the Key Project of Hunan Provincial Natural Science Foundation(Grant No.05JJ20012)Supported by Project of Hunan Provincial Research Scheme(Grant No.05CK3034)
文摘Kilns are the key equipment in the metallurgy,architectural and chemistry industry.It is the statically indeterminate system with over load,large torque and multi-support.The kiln move axis warp resulting in that the load distribution is asymmetry,cause many mechanical failure and safe accidents and the interruption of the produce,which bring a great losses.Treating the distribution of the kiln load and the complexity of the stiffness change,the all-purpose model and matrix,used to solve the variable-stiffness beam upon complex load,are established in this paper.The resultant force of kiln in vertical and horizontal direction is calculated.Accordingly,the liner formulas for calculating the supporting force of the support wheels are obtained,and the wheel supporting force also can be easily obtained based on each shell warp.This will provide theory conference for safety management and rational maintenance.
基金supported by the National Natural Science Foundation of China(Grant Nos.52422809 and 52027811).
文摘The precast segmental column(PSC)plays a vital role in both the design of new bridges and the rehabilitation of existing ones.Previous studies of PSCs have primarily focused on their individual seismic behavior.However,research on the seismic performance of entire bridges supported by PSCs,particularly those incorporating soil-structure interaction(SSI),remains limited.Moreover,the amplification of earthquake waves as they propagate along the pile foundation to the surface,coupled with the coherency loss between earthquake motions at varying supports,may further impact the seismic responses of such bridges.This study systematically assesses the seismic performance of a PSC bridge(PSCB)supported by pile foundations considering the effects of SSI and depth-varying multi-support ground motions.Moreover,a benchmark bridge with the traditional monolithic column is also analyzed for comparison.The seismic fragility of bridges is calculated based on nonlinear time history analyses and joint probability density functions for both peak and residual responses.Parameter studies are conducted to reveal the influences of sSI,non-uniform excitation,and depth-varying earthquake loads on seismic performance assessments.This paper offers valuable insights for the reliable analysis of seismic response and fragility and the safety design of PSCB systems.
基金the National Natural Science Foundation of China (Grant No.50108003)
文摘The vibration tests of Laoshan bicycle gymnasium for the Olympic Games are performed under multi-support excitations in order to verify the effectiveness of multi-support time history method. The excitation sources come from the impact forces acting on the ring beam of the reticulated structure, on the basis of which the records of motions of each excited point and corresponding structural vibration responses are all collected. The theoretical analytical model of the structure is further established and the structural dynamic responses are obtained subjected to the same excitation case via multi-support time history method. The calculation results are generally in agreement with those of the test in both time domain and frequency domain, which verify the effectiveness of multi-support time history method. The vibration test can also provide references for long-span structures under multi-support excitations.
文摘人工智能(AI)作为引领新一轮科技革命的核心技术,已深度融入临床医学的各个环节。自20世纪50年代诞生以来,AI经历了从符号逻辑到深层神经网络的跨越式发展,目前已在疾病诊断、方案制订、药物研发及医院管理中展现出广阔的应用前景。国际监管方面,美国食品药品监督管理局(FDA)已建立并持续更新AI-Enabled Medical Device List,并对相关软件和器械实施风险分级与全生命周期监管。国内方面,中国在积极推进“AI+医疗卫生”行动、促进新技术临床转化的同时,监管部门亦同步加强制度建设,在医疗器械注册审评、AI医疗软件风险管理、数据安全与隐私保护等方面逐步完善规范要求,形成覆盖技术准入、应用实施与风险防控的监管体系,为AI技术在临床实践中的规范落地提供制度支撑。在上述国际与国内监管框架的共同推动下,AI技术正逐步应用于临床诊疗与公共卫生管理,在提升基层医疗服务能力、肿瘤早筛及流行病学管理等方面展现出重要应用前景。该文综述了AI在临床医学中的最新应用进展,涵盖计算机视觉与自然语言处理等技术基础,系统分析了其在实际应用中面临的数据隐私、算法透明度及法律责任界定等挑战,并强调AI医疗应用应坚持“以人为本”和“人类主导”原则,通过多中心验证与协同监管,推动精准医学的可持续发展。
