A bearing capacity evaluation for the surface strip foundation on a working platform modelled on a twolayered substrate is considered in the study.The upper layer is assumed as man-made and wellcontrolled and thus non...A bearing capacity evaluation for the surface strip foundation on a working platform modelled on a twolayered substrate is considered in the study.The upper layer is assumed as man-made and wellcontrolled and thus non-variable.The lower layer modelling natural cohesive soil is subjected to spatial variability of undrained shear strength.The random failure mechanism method(RFMM)is used to evaluate the bearing capacity.This approach employs a kinematic assessment of the critical load and incorporates the averaging of three-dimensional(3 D)random field along dissipation surfaces that result from the failure mechanism geometry.A novel version of the approach considering an additional linear trend of undrained shear strength in the spatially variable layer is proposed.The high efficiency of the RFMM algorithm is preserved.The influences of foundation length,trend slope in the spatially variable layer,fluctuation scales,and thickness of the homogenous sand layer on the resulting bearing capacity evaluations are analysed.Moreover,for selected cases,verification of the RFMM based assessment obtained using random finite difference method(RFDM)based on 3 D analysis is provided.Two types of analyses are performed using RFDM based on associated and non-associated flow rules.For associated flow rule which corresponds to RFMM,the RFMM is conservative and efficient and thus it seems preferable.However,if RFDM employs non-associated flow rule(much lower dilation angle for sand layer),the efficient RFMM is no longer conservative.For this situation,a combined approach that improves the efficiency of the numerical method is suggested.展开更多
A coupled electromechanical dynamic model for a working platform supported by an active magneticguide(AMG)is set up according to the special stiffness and damping theory of maglev system and theunique vibration of the...A coupled electromechanical dynamic model for a working platform supported by an active magneticguide(AMG)is set up according to the special stiffness and damping theory of maglev system and theunique vibration of the working platform for a machine tool.The dynamic characteristics of a workingplatform supported by an AMG are studied using different groups of control parameters.Results show thatthe dynamic characteristics of the platform system,such as critical vibration frequency,vibration modeand so on,can be improved by adjusting the control parameters.This research offers theoretical supportfor ultra-high-speed and ultra-precise machine working platform designs,including the structure of plat-forms,the design of electromagnets,and the establishment of the control parameters.展开更多
Under the employment model of online car-hailing platforms,the extension of working hours and increase of labor intensity for practitioners are driven by the orders from these platform companies and labor-related thir...Under the employment model of online car-hailing platforms,the extension of working hours and increase of labor intensity for practitioners are driven by the orders from these platform companies and labor-related third parties.Also,they are more attributable to the internal driving force of practitioners themselves who hope to have more orders and earn more.It is impossible to apply the regulation system of the existing labor law to protect the rights and interests of employees in terms of working hours and labor intensity.The author suggests that the state should make special labor legislation to make the following targeted provisions:Online car-hailing platform companies and labor-related third parties that implement labor management and control over practitioners shall,on the premise of abiding by labor standards and industry rules,set various reasonable indicators of working hours and labor intensity through rules and take effective technical measures to control these two dimensions,so that practitioners can avoid serious overwork.Besides,by encouraging the provision of certain convenience for practitioners to take intermittent breaks,jointly building a compatibility system for different online car-hailing platforms,and establishing relevant operating rules,we can restrain practitioners from being seriously overworked.This is actually a multi-cooperative boosting legislative regulation approach.展开更多
Rigid model of the aerial work platform and hydraulic model of the oscillating mechanism were established with ADAMS. The simulation of two parameters, cy-linder force and oil chamber pressure, was carried out. The si...Rigid model of the aerial work platform and hydraulic model of the oscillating mechanism were established with ADAMS. The simulation of two parameters, cy-linder force and oil chamber pressure, was carried out. The simulation result is useful to the design of the oscillating mechanism.展开更多
文摘A bearing capacity evaluation for the surface strip foundation on a working platform modelled on a twolayered substrate is considered in the study.The upper layer is assumed as man-made and wellcontrolled and thus non-variable.The lower layer modelling natural cohesive soil is subjected to spatial variability of undrained shear strength.The random failure mechanism method(RFMM)is used to evaluate the bearing capacity.This approach employs a kinematic assessment of the critical load and incorporates the averaging of three-dimensional(3 D)random field along dissipation surfaces that result from the failure mechanism geometry.A novel version of the approach considering an additional linear trend of undrained shear strength in the spatially variable layer is proposed.The high efficiency of the RFMM algorithm is preserved.The influences of foundation length,trend slope in the spatially variable layer,fluctuation scales,and thickness of the homogenous sand layer on the resulting bearing capacity evaluations are analysed.Moreover,for selected cases,verification of the RFMM based assessment obtained using random finite difference method(RFDM)based on 3 D analysis is provided.Two types of analyses are performed using RFDM based on associated and non-associated flow rules.For associated flow rule which corresponds to RFMM,the RFMM is conservative and efficient and thus it seems preferable.However,if RFDM employs non-associated flow rule(much lower dilation angle for sand layer),the efficient RFMM is no longer conservative.For this situation,a combined approach that improves the efficiency of the numerical method is suggested.
基金the National High Technology Research and Development Program of China(No2001AA423310)
文摘A coupled electromechanical dynamic model for a working platform supported by an active magneticguide(AMG)is set up according to the special stiffness and damping theory of maglev system and theunique vibration of the working platform for a machine tool.The dynamic characteristics of a workingplatform supported by an AMG are studied using different groups of control parameters.Results show thatthe dynamic characteristics of the platform system,such as critical vibration frequency,vibration modeand so on,can be improved by adjusting the control parameters.This research offers theoretical supportfor ultra-high-speed and ultra-precise machine working platform designs,including the structure of plat-forms,the design of electromagnets,and the establishment of the control parameters.
基金the final result of the general topic of the National Rule of Law and Law Science The-oretical Research Project launched by the Ministry of Justice of the PRC,“Challenges Posed by the Sharing Economy to Labor Law and Social Insurance Law and Corresponding Solutions”(19SFB2050)the funded result of the“CUPL Emerging Discipline Creation and Construction Program”
文摘Under the employment model of online car-hailing platforms,the extension of working hours and increase of labor intensity for practitioners are driven by the orders from these platform companies and labor-related third parties.Also,they are more attributable to the internal driving force of practitioners themselves who hope to have more orders and earn more.It is impossible to apply the regulation system of the existing labor law to protect the rights and interests of employees in terms of working hours and labor intensity.The author suggests that the state should make special labor legislation to make the following targeted provisions:Online car-hailing platform companies and labor-related third parties that implement labor management and control over practitioners shall,on the premise of abiding by labor standards and industry rules,set various reasonable indicators of working hours and labor intensity through rules and take effective technical measures to control these two dimensions,so that practitioners can avoid serious overwork.Besides,by encouraging the provision of certain convenience for practitioners to take intermittent breaks,jointly building a compatibility system for different online car-hailing platforms,and establishing relevant operating rules,we can restrain practitioners from being seriously overworked.This is actually a multi-cooperative boosting legislative regulation approach.
文摘Rigid model of the aerial work platform and hydraulic model of the oscillating mechanism were established with ADAMS. The simulation of two parameters, cy-linder force and oil chamber pressure, was carried out. The simulation result is useful to the design of the oscillating mechanism.
