Self-vibrating systems comprised of active materials have great potential for application in the fields of energy harvesting,actuation,bionic instrumentation,and autonomous robotics.However,it is challenging to obtain...Self-vibrating systems comprised of active materials have great potential for application in the fields of energy harvesting,actuation,bionic instrumentation,and autonomous robotics.However,it is challenging to obtain analytical solutions describing these systems,which hinders analysis and design.In this work,we propose a self-vibrating liquid crystal elastomer(LCE)fiber-spring system exposed to spatially-constant gradient light,and determine analytical solutions for its amplitude and period.First,using a dynamic model of LCE,we obtain the equations governing the self-vibration.Then,we analyze two different motion states and elucidate the mechanism of self-vibration.Subsequently,we derive analytical solutions for the amplitude and frequency using the multi-scale method,and compare the solutions with numerical results.The analytical outcomes are shown to be consistent with the numerical calculations,while taking far less computational time.Our findings reveal the utility of the multi-scale method in describing self-vibration,which may contribute to more efficient and accurate analyses of self-vibrating systems.展开更多
As a crucial component of intelligent chassis systems,air suspension significantly enhances driver comfort and vehicle stability.To further improve the adaptability of commercial vehicles to complex and variable road ...As a crucial component of intelligent chassis systems,air suspension significantly enhances driver comfort and vehicle stability.To further improve the adaptability of commercial vehicles to complex and variable road conditions,this paper proposes a linear motor active suspension with quasi-zero stiffness(QZS)air spring system.Firstly,a dynamic model of the linear motor active suspension with QZS air spring system is established.Secondly,considering the random uncertainties in the linear motor parameters due to manufacturing and environmental factors,a dynamic model and state equations incorporating these uncertainties are constructed using the polynomial chaos expansion(PCE)method.Then,based on H_(2) robust control theory and the Kalman filter,a state feedback control law is derived,accounting for the random parameter uncertainties.Finally,simulation and hardware-in-the-loop(HIL)experimental results demonstrate that the PCE-H_(2) robust controller not only provides better performance in terms of vehicle ride comfort compared to general H_(2) robust controller but also exhibits higher robustness to the effects of random uncertain parameters,resulting in more stable control performance.展开更多
Free vibrations of a beam-mass-spring system with different boundary conditions are analyzed both analyt- ically and numerically. In the analytical analysis, the system is divided into three subsystems and the effects...Free vibrations of a beam-mass-spring system with different boundary conditions are analyzed both analyt- ically and numerically. In the analytical analysis, the system is divided into three subsystems and the effects of the spring and the point mass are considered as internal boundary con- ditions between any two neighboring subsystems. The par- tial differential equations governing the motion of the sub- systems and internal boundary conditions are then solved us- ing the method of separation of variables. In the numerical analysis, the whole system is considered as a single system and the effects of the spring and point mass are introduced using the Dirac delta function. The Galerkin method is then employed to discretize the equation of motion and the result- ing set of ordinary differential equations are solved via eigen- value analysis. Analytical and numerical results are shown to be in very good agreement.展开更多
In order to study the hydrodynamic characteristics of the karst aquifers in northern China,time series analyses(correlation and spectral analysis in addition with hydrograph recession analysis)are applied on Baotu Spr...In order to study the hydrodynamic characteristics of the karst aquifers in northern China,time series analyses(correlation and spectral analysis in addition with hydrograph recession analysis)are applied on Baotu Spring and Heihu Spring in Jinan karst spring system,a typical karst spring system in northern China.Results show that the auto-correlation coefficient of spring water level reaches the value of 0.2 after 123 days and 117 days for Baotu Spring and Heihu Spring,respectively.The regulation time obtained from the simple spectral density function in the same period is 187 days and 175 days for Baotu Spring and Heihu Spring.The auto-correlation coefficient of spring water level reaches the value of 0.2 in 34-82 days,and regulation time ranges among 40-59 days for every single hydrological year.The delay time between precipitation and spring water level obtained from cross correlation function is around 56 days for the period of 2012-2019,and varies among 30-79 days for every single hydrological year.In addition,the spectral bands in cross amplitude functions and gain functions are small with 0.02,and the values in the coherence functions are small.All these behaviors illustrate that Jinan karst spring system has a strong memory effect,large storage capacity,noticeable regulation effect,and time series analysis is a useful tool for studying the hydrodynamic characteristics of karst spring system in northern China.展开更多
The geothermal waters of south hot spring, small hot spring and Qiaokouba in Chongqing, are all part of the south hot spring geothermal water system. Exploitation has caused a decline in the water levels of the south ...The geothermal waters of south hot spring, small hot spring and Qiaokouba in Chongqing, are all part of the south hot spring geothermal water system. Exploitation has caused a decline in the water levels of the south and small hot springs, which have not flowed naturally for 15 years. Now, bores pump geothermal water to the springs. If the water level drops below the elevation of the rivers, river-water will replenish the geothermal water, destroying this resource. It is therefore an urgent task to model the geothermal water system, to enable sustainable development and continued use of the geothermal water in Qiaokouba. A numerical simulation of the geothermal water system was adopted and a quantitative study on the planning scheme was carried out. A mathematical model was set up to simulate the whole geothermal water system, based on data from the research sites. The model determined the maximum sustainable water yield in Qiaokouba and the two hot springs, and the south hot spring and small hot spring sustainable yields are 1 100 m^3/d and 700 m^3/d from 2006 to 2010, 1 300 m^3/d and 1 000 m^3/d from 2011 to 2015, and 1 500 m^3/d and 1 200 m^3/d from 2016 to 2036. The maximum exploitable yield is 3 300 m^3/d from 2006 to 2036 in Qiaokouba. The model supplies a basis to adequately exploit and effectively protect the geothermal water resources, and to continue to develop the geothermal water as a tourist attraction in Chongqing.展开更多
Based on the lightning monitoring data, automatic and routine weather station observation data in spring （March-May） of 2013 of Sichuan Province, the corresponding relationship between the spatial distribution and t...Based on the lightning monitoring data, automatic and routine weather station observation data in spring （March-May） of 2013 of Sichuan Province, the corresponding relationship between the spatial distribution and the different regions, and the characteristics of atmospheric circulation and evolution of influence the sys- tem were analyzed and summarized. The results show that： the lightning and thunderstorm showed great regional differences in the spring of 2013 in Sichuan Province and the thunderstorm activity period was not the same in different areas. Because of the change of atmospheric circulation, the influence system from March to May corresponding to the thunderstorms in Sichuan tended to be volatile, also.展开更多
This paper’s simple ecological model to simulate the ecosystem variation and the vertical carbon flux in the central part of the East China Sea in spring, inter-reated the phytoplankton, zooplankton,autotrophic and h...This paper’s simple ecological model to simulate the ecosystem variation and the vertical carbon flux in the central part of the East China Sea in spring, inter-reated the phytoplankton, zooplankton,autotrophic and heterotrophic bacterioplankton, nitrate, and dissolved organic carbon (DOC) in a run lasting 90 days. Except for DOC, because of poor observation precision,the major seasonal features of the vertical distribution for these components can be simulated by this model. The results show that spring bloom is just a short period of 1-2 weeks and that deposit carbon flux at the bottom interface is about 200 mg /m2 ·d in the first 20 days and then reaches its maximum of 1500mg/m2·d about 2 months later after the spring bloom.展开更多
Short suspension system has an indispensable effect on vehicle handling and ride,so,optimization of vehicle suspension system is one of the most effective methods,which could considerably enhance the vehicle stability...Short suspension system has an indispensable effect on vehicle handling and ride,so,optimization of vehicle suspension system is one of the most effective methods,which could considerably enhance the vehicle stability and controllability.Motion control,stability maintenance and ride comfort improvement are fundamental issues in design of suspension system of off-road vehicles.In this work,a dependent suspension system mostly used in off-road vehicles is modeled using Trucksim software.Then,geometric parameters of suspension system are optimized using integrated anti-roll bar and coiling spring in a way that ride comfort,handling and stability of vehicle are improved.The simulation results of suspension system and variations of geometric parameters due to road roughness and different steering angles are presented in Trucksim and effects of optimization of suspension system during various driving maneuvers in both optimized and un-optimized conditions are compared.The simulation results indicate that the type of suspension system and geometric parameters have significant effect on vehicle performance.展开更多
Quasi-zero stiffness(QZS) device is widely studied for their better performance in low-frequency and micro-vibration isolation due to the high-static and low-dynamic(HSLD) stiffness characteristics.The previous QZS is...Quasi-zero stiffness(QZS) device is widely studied for their better performance in low-frequency and micro-vibration isolation due to the high-static and low-dynamic(HSLD) stiffness characteristics.The previous QZS isolator with determined parameters is not suitable for variable isolated mass.In this study,a novel compound regulative quasi-zero stiffness air spring(CRQSAS)has been proposed and designed by introducing a bidirectional regulator for the horizontal air springs.The CRQSAS could change the quasi-zero region depending on the payload.To identify the parameters of the convoluted air spring(CAS) and novel rubber air spring(NRAS),the air spring testing system is established.The stiffness functions of air springs are obtained by the multi-parameter fitting method.According to the structure of the CRQSAS,the dynamic model of the system is analyzed and simplified by Taylor Expansion.The harmonic balance method(HBM) is applied to calculate the frequency response and absolute displacement transmissibility.An experimental prototype has been set up to verify the theoretical model and simulation.Compared with the single NRAS,CRQSAS performs better in low-frequency and micro-amplitude vibration.The research proves that CRQSAS is a passive device widely applied for improving isolation precision under low-frequency vibration.展开更多
To reduce the roll movement of an air spring passenger car, an active anti-roll system is developed, which is constructed with hydraulic and pneumatic units to change spring rate during cornering. For the comparing re...To reduce the roll movement of an air spring passenger car, an active anti-roll system is developed, which is constructed with hydraulic and pneumatic units to change spring rate during cornering. For the comparing research between the passive and active system, a two-track vehicle model and a co-simulation model of air spring system are built. For the simulation research on the linear movement of the actuator, a mathematical model is considered as dynamical subsystem in the co-simulation model. To active control the roll angle of vehicle body, a sliding-mode controller with optimized control parameters for the test vehicle is introduced into the model. The characteristics of sliding-mode controller is discussed and the validation of active antiroll control is proved by comparison with other control methods. The results show that the roll angle of air spring vehicle is reduced obviously with the active anti-roll actuator in comparison with that of the passive system. Compared with other control methods, sliding-mode controller has an advantage of shortest switching times, which leads to a longer lifetime of actuator and valves.展开更多
BACKGROUND： Spring water therapies have been used since at least 1550 BC. Despite the growing body of evidence supporting these therapies for a range of conditions, including musculoskeletal, dermatological, respirat...BACKGROUND： Spring water therapies have been used since at least 1550 BC. Despite the growing body of evidence supporting these therapies for a range of conditions, including musculoskeletal, dermatological, respiratory and cardiovascular conditions, they do not currently form part of mainstream healthcare in many countries. The protocol established in this paper aims to support systematic reviews that examine the health outcomes associated with human exposure to regional spring waters, using the Australia and New Zealand context as a case study. METHODS/DESIGN： The protocol searches for studies in eight health/medical databases, searches three local health/medical journals, and includes forwards and backwards searching. Standard systematic review methods are used including： specifying pre-deterrnined inclusion criteria and data management plans, appraising the studies for bias, and allocation to a hierarchy of evidence. DISCUSSION： The protocol supports a review and comprehensive synthesis of the current evidence regarding the health effects of natural spring water, and can be adapted for reviews in other regions. From this evidence, recommendations regarding practice and future research can be made on the therapeutic role of spring water.展开更多
As the rapid growth of population and social economy, the situation of water resources shortage in Beijing city becomes more and more serious. Karst groundwater in Beijing has great potential for development. The reas...As the rapid growth of population and social economy, the situation of water resources shortage in Beijing city becomes more and more serious. Karst groundwater in Beijing has great potential for development. The reasonable exploitation of karst groundwater can enhance the water-supply stability of Beijing city. Firstly, the distribution of springs has been investigated in Fangshan, Beijing, and the characteristics of these springs have also been analyzed. Secondly, the hydrogeological conceptual model has been built, based on this, the groundwater flow numerical simulation model was established, and the parameter identification and validation of the model were performed under groundwater level and spring discharge. The results shows that the simulated values of groundwater level and spring discharge are very close to measured values, and the model can be used for groundwater resources evaluation and spring discharge prediction. Finally, a reasonable exploitation design has been developed with three exploitation scenarios considering the spring discharge protection; meanwhile, the quantity of groundwater resources was evaluated in the karst aquifer. The simulation results indicate that different exploitation yields have a significant impact on spring discharge; and the effective measures should be taken to protect the spring discharge.展开更多
This article gives an overview of important property of the integrated management of agricultural product quality safety system,analyzes the lightweight characteristics of Spring technical system,hierarchical organiza...This article gives an overview of important property of the integrated management of agricultural product quality safety system,analyzes the lightweight characteristics of Spring technical system,hierarchical organization of MVC,and the technology SSH+Ajax associated with the Spring framework system.On the basis of this technical system,we design the quality management system of agricultural products under B/S model.This article points out that this system is realized mainly through consumers'information feedback and order management;then discusses operation environment,expandability,portability and security of the system.展开更多
Guided by the theory of groundwater system, based on the groundwater level data from the northern basin of Laiyuan Spring area, the authors took into account factors such as the lithology, geological structure and top...Guided by the theory of groundwater system, based on the groundwater level data from the northern basin of Laiyuan Spring area, the authors took into account factors such as the lithology, geological structure and topography to study the relationship between groundwater recharge, runoff and drainage in this area. It was concluded that the infiltration of atmospheric precipitation is the main source of groundwater supply in this area; the upper layer of the Spring area is distributed with the Cambrian-Lower Ordovician karst water, and the lower layer is filled with the Jixian system karst water. The upper layer of karst water supplies to the lower layer of karst water or the pore water in loose strata through the fault while the lower layer of karst water runs to the three strong runoff belts from the east and west sides of the watershed, southwards into the basin, partially replenishing the pore water in loose strata, or forming fault Springs(e.g. Nanguan Spring, Beihai Spring) when dolomite movement encounters faults. Replenished by atmospheric precipitation and the upper and lower layers of karst waters, the pore water in loose strata joins the groundwater in the southern basin and then flows eastwards, in the end it flows out of the system in Shangfanpu. Through the analyses of groundwater level data and hydrogeological drilling data, based on groundwater D and ^(18) O isotope test results, the karst groundwater circulation system in the northern basin of Laiyuan Spring area is further verified, which provides hydrogeological basis for water resources development and utilization as well as protection in this area.展开更多
In order to study an isolation system of rolling friction with springs, computer programs were compiled to evaluate the seismic performance based on its movement characteristics. Through the programs, the influences o...In order to study an isolation system of rolling friction with springs, computer programs were compiled to evaluate the seismic performance based on its movement characteristics. Through the programs, the influences of various seismic performance factors, e.g., rolling friction coefficient, spring constant, were systematically investigated. Results show that by increasing the rolling friction coefficient, the structural relative displacement due to seismic load effectively decreases, while the structural response magnitude varies mainly depending on the correlations between the following factors: the spring constant, the earthquake intensity, and the rolling friction coefficient. Furthermore, increasing the spring constant can decrease the structural relative displacement, as well as residual displacement, however, it increases the structural response magnitude. Finally, based on the analyses of various seismic performance factors subjected to the scenario earthquakes, optimized theoretical seismic performance can be achieved by reasonably combining the spring constant and the rolling friction coefficient.展开更多
基金supported by the National Natural Science Foundation of China(No.12172001)the University Natural Science Research Project of Anhui Province(No.2022AH020029)+1 种基金the Anhui Provincial Natural Science Foundation(Nos.2208085Y01 and 2008085QA23)the Housing and Urban-Rural Development Science and Technology Project of Anhui Province(No.2023-YF129),China.
文摘Self-vibrating systems comprised of active materials have great potential for application in the fields of energy harvesting,actuation,bionic instrumentation,and autonomous robotics.However,it is challenging to obtain analytical solutions describing these systems,which hinders analysis and design.In this work,we propose a self-vibrating liquid crystal elastomer(LCE)fiber-spring system exposed to spatially-constant gradient light,and determine analytical solutions for its amplitude and period.First,using a dynamic model of LCE,we obtain the equations governing the self-vibration.Then,we analyze two different motion states and elucidate the mechanism of self-vibration.Subsequently,we derive analytical solutions for the amplitude and frequency using the multi-scale method,and compare the solutions with numerical results.The analytical outcomes are shown to be consistent with the numerical calculations,while taking far less computational time.Our findings reveal the utility of the multi-scale method in describing self-vibration,which may contribute to more efficient and accurate analyses of self-vibrating systems.
基金Supported by National Natural Science Foundation of China(Grant No.51875256)Open Platform Fund of Human Institute of Technology(Grant No.KFA22009).
文摘As a crucial component of intelligent chassis systems,air suspension significantly enhances driver comfort and vehicle stability.To further improve the adaptability of commercial vehicles to complex and variable road conditions,this paper proposes a linear motor active suspension with quasi-zero stiffness(QZS)air spring system.Firstly,a dynamic model of the linear motor active suspension with QZS air spring system is established.Secondly,considering the random uncertainties in the linear motor parameters due to manufacturing and environmental factors,a dynamic model and state equations incorporating these uncertainties are constructed using the polynomial chaos expansion(PCE)method.Then,based on H_(2) robust control theory and the Kalman filter,a state feedback control law is derived,accounting for the random parameter uncertainties.Finally,simulation and hardware-in-the-loop(HIL)experimental results demonstrate that the PCE-H_(2) robust controller not only provides better performance in terms of vehicle ride comfort compared to general H_(2) robust controller but also exhibits higher robustness to the effects of random uncertain parameters,resulting in more stable control performance.
文摘Free vibrations of a beam-mass-spring system with different boundary conditions are analyzed both analyt- ically and numerically. In the analytical analysis, the system is divided into three subsystems and the effects of the spring and the point mass are considered as internal boundary con- ditions between any two neighboring subsystems. The par- tial differential equations governing the motion of the sub- systems and internal boundary conditions are then solved us- ing the method of separation of variables. In the numerical analysis, the whole system is considered as a single system and the effects of the spring and point mass are introduced using the Dirac delta function. The Galerkin method is then employed to discretize the equation of motion and the result- ing set of ordinary differential equations are solved via eigen- value analysis. Analytical and numerical results are shown to be in very good agreement.
基金This study is supported by the geological survey project:National Glacier and Desertification Remote Sensing Geological Survey(DD20190515)Youth Innovation Fund of China Aero Geophysical Prospecting and Remote Sensing Center for Natural Resources(2020YFL18).
文摘In order to study the hydrodynamic characteristics of the karst aquifers in northern China,time series analyses(correlation and spectral analysis in addition with hydrograph recession analysis)are applied on Baotu Spring and Heihu Spring in Jinan karst spring system,a typical karst spring system in northern China.Results show that the auto-correlation coefficient of spring water level reaches the value of 0.2 after 123 days and 117 days for Baotu Spring and Heihu Spring,respectively.The regulation time obtained from the simple spectral density function in the same period is 187 days and 175 days for Baotu Spring and Heihu Spring.The auto-correlation coefficient of spring water level reaches the value of 0.2 in 34-82 days,and regulation time ranges among 40-59 days for every single hydrological year.The delay time between precipitation and spring water level obtained from cross correlation function is around 56 days for the period of 2012-2019,and varies among 30-79 days for every single hydrological year.In addition,the spectral bands in cross amplitude functions and gain functions are small with 0.02,and the values in the coherence functions are small.All these behaviors illustrate that Jinan karst spring system has a strong memory effect,large storage capacity,noticeable regulation effect,and time series analysis is a useful tool for studying the hydrodynamic characteristics of karst spring system in northern China.
文摘The geothermal waters of south hot spring, small hot spring and Qiaokouba in Chongqing, are all part of the south hot spring geothermal water system. Exploitation has caused a decline in the water levels of the south and small hot springs, which have not flowed naturally for 15 years. Now, bores pump geothermal water to the springs. If the water level drops below the elevation of the rivers, river-water will replenish the geothermal water, destroying this resource. It is therefore an urgent task to model the geothermal water system, to enable sustainable development and continued use of the geothermal water in Qiaokouba. A numerical simulation of the geothermal water system was adopted and a quantitative study on the planning scheme was carried out. A mathematical model was set up to simulate the whole geothermal water system, based on data from the research sites. The model determined the maximum sustainable water yield in Qiaokouba and the two hot springs, and the south hot spring and small hot spring sustainable yields are 1 100 m^3/d and 700 m^3/d from 2006 to 2010, 1 300 m^3/d and 1 000 m^3/d from 2011 to 2015, and 1 500 m^3/d and 1 200 m^3/d from 2016 to 2036. The maximum exploitable yield is 3 300 m^3/d from 2006 to 2036 in Qiaokouba. The model supplies a basis to adequately exploit and effectively protect the geothermal water resources, and to continue to develop the geothermal water as a tourist attraction in Chongqing.
文摘Based on the lightning monitoring data, automatic and routine weather station observation data in spring （March-May） of 2013 of Sichuan Province, the corresponding relationship between the spatial distribution and the different regions, and the characteristics of atmospheric circulation and evolution of influence the sys- tem were analyzed and summarized. The results show that： the lightning and thunderstorm showed great regional differences in the spring of 2013 in Sichuan Province and the thunderstorm activity period was not the same in different areas. Because of the change of atmospheric circulation, the influence system from March to May corresponding to the thunderstorms in Sichuan tended to be volatile, also.
文摘This paper’s simple ecological model to simulate the ecosystem variation and the vertical carbon flux in the central part of the East China Sea in spring, inter-reated the phytoplankton, zooplankton,autotrophic and heterotrophic bacterioplankton, nitrate, and dissolved organic carbon (DOC) in a run lasting 90 days. Except for DOC, because of poor observation precision,the major seasonal features of the vertical distribution for these components can be simulated by this model. The results show that spring bloom is just a short period of 1-2 weeks and that deposit carbon flux at the bottom interface is about 200 mg /m2 ·d in the first 20 days and then reaches its maximum of 1500mg/m2·d about 2 months later after the spring bloom.
文摘Short suspension system has an indispensable effect on vehicle handling and ride,so,optimization of vehicle suspension system is one of the most effective methods,which could considerably enhance the vehicle stability and controllability.Motion control,stability maintenance and ride comfort improvement are fundamental issues in design of suspension system of off-road vehicles.In this work,a dependent suspension system mostly used in off-road vehicles is modeled using Trucksim software.Then,geometric parameters of suspension system are optimized using integrated anti-roll bar and coiling spring in a way that ride comfort,handling and stability of vehicle are improved.The simulation results of suspension system and variations of geometric parameters due to road roughness and different steering angles are presented in Trucksim and effects of optimization of suspension system during various driving maneuvers in both optimized and un-optimized conditions are compared.The simulation results indicate that the type of suspension system and geometric parameters have significant effect on vehicle performance.
基金supported by the National Key Research and Development Project (Grant No.2021YFC0122502)the National Natural Science Foundation of China (Grant Nos.52205043 and 52275043)。
文摘Quasi-zero stiffness(QZS) device is widely studied for their better performance in low-frequency and micro-vibration isolation due to the high-static and low-dynamic(HSLD) stiffness characteristics.The previous QZS isolator with determined parameters is not suitable for variable isolated mass.In this study,a novel compound regulative quasi-zero stiffness air spring(CRQSAS)has been proposed and designed by introducing a bidirectional regulator for the horizontal air springs.The CRQSAS could change the quasi-zero region depending on the payload.To identify the parameters of the convoluted air spring(CAS) and novel rubber air spring(NRAS),the air spring testing system is established.The stiffness functions of air springs are obtained by the multi-parameter fitting method.According to the structure of the CRQSAS,the dynamic model of the system is analyzed and simplified by Taylor Expansion.The harmonic balance method(HBM) is applied to calculate the frequency response and absolute displacement transmissibility.An experimental prototype has been set up to verify the theoretical model and simulation.Compared with the single NRAS,CRQSAS performs better in low-frequency and micro-amplitude vibration.The research proves that CRQSAS is a passive device widely applied for improving isolation precision under low-frequency vibration.
基金Sponsored by German Academic Exchange Service(Deutsche Akademische Austauschdienst)
文摘To reduce the roll movement of an air spring passenger car, an active anti-roll system is developed, which is constructed with hydraulic and pneumatic units to change spring rate during cornering. For the comparing research between the passive and active system, a two-track vehicle model and a co-simulation model of air spring system are built. For the simulation research on the linear movement of the actuator, a mathematical model is considered as dynamical subsystem in the co-simulation model. To active control the roll angle of vehicle body, a sliding-mode controller with optimized control parameters for the test vehicle is introduced into the model. The characteristics of sliding-mode controller is discussed and the validation of active antiroll control is proved by comparison with other control methods. The results show that the roll angle of air spring vehicle is reduced obviously with the active anti-roll actuator in comparison with that of the passive system. Compared with other control methods, sliding-mode controller has an advantage of shortest switching times, which leads to a longer lifetime of actuator and valves.
文摘BACKGROUND： Spring water therapies have been used since at least 1550 BC. Despite the growing body of evidence supporting these therapies for a range of conditions, including musculoskeletal, dermatological, respiratory and cardiovascular conditions, they do not currently form part of mainstream healthcare in many countries. The protocol established in this paper aims to support systematic reviews that examine the health outcomes associated with human exposure to regional spring waters, using the Australia and New Zealand context as a case study. METHODS/DESIGN： The protocol searches for studies in eight health/medical databases, searches three local health/medical journals, and includes forwards and backwards searching. Standard systematic review methods are used including： specifying pre-deterrnined inclusion criteria and data management plans, appraising the studies for bias, and allocation to a hierarchy of evidence. DISCUSSION： The protocol supports a review and comprehensive synthesis of the current evidence regarding the health effects of natural spring water, and can be adapted for reviews in other regions. From this evidence, recommendations regarding practice and future research can be made on the therapeutic role of spring water.
基金generously supported by National Natural Science Foundation of China(Grant No.51459003)the Project of Karst Groundwater Resources Exploration and Assessment in Beijing(BJYRS-ZT-01)
文摘As the rapid growth of population and social economy, the situation of water resources shortage in Beijing city becomes more and more serious. Karst groundwater in Beijing has great potential for development. The reasonable exploitation of karst groundwater can enhance the water-supply stability of Beijing city. Firstly, the distribution of springs has been investigated in Fangshan, Beijing, and the characteristics of these springs have also been analyzed. Secondly, the hydrogeological conceptual model has been built, based on this, the groundwater flow numerical simulation model was established, and the parameter identification and validation of the model were performed under groundwater level and spring discharge. The results shows that the simulated values of groundwater level and spring discharge are very close to measured values, and the model can be used for groundwater resources evaluation and spring discharge prediction. Finally, a reasonable exploitation design has been developed with three exploitation scenarios considering the spring discharge protection; meanwhile, the quantity of groundwater resources was evaluated in the karst aquifer. The simulation results indicate that different exploitation yields have a significant impact on spring discharge; and the effective measures should be taken to protect the spring discharge.
文摘This article gives an overview of important property of the integrated management of agricultural product quality safety system,analyzes the lightweight characteristics of Spring technical system,hierarchical organization of MVC,and the technology SSH+Ajax associated with the Spring framework system.On the basis of this technical system,we design the quality management system of agricultural products under B/S model.This article points out that this system is realized mainly through consumers'information feedback and order management;then discusses operation environment,expandability,portability and security of the system.
基金supported by the geological survey project of China Geological Survey(CGS)“1:50000 Hydrogeological Surveys in Taihang Mountainous Area(9)”(No.12120114010801)
文摘Guided by the theory of groundwater system, based on the groundwater level data from the northern basin of Laiyuan Spring area, the authors took into account factors such as the lithology, geological structure and topography to study the relationship between groundwater recharge, runoff and drainage in this area. It was concluded that the infiltration of atmospheric precipitation is the main source of groundwater supply in this area; the upper layer of the Spring area is distributed with the Cambrian-Lower Ordovician karst water, and the lower layer is filled with the Jixian system karst water. The upper layer of karst water supplies to the lower layer of karst water or the pore water in loose strata through the fault while the lower layer of karst water runs to the three strong runoff belts from the east and west sides of the watershed, southwards into the basin, partially replenishing the pore water in loose strata, or forming fault Springs(e.g. Nanguan Spring, Beihai Spring) when dolomite movement encounters faults. Replenished by atmospheric precipitation and the upper and lower layers of karst waters, the pore water in loose strata joins the groundwater in the southern basin and then flows eastwards, in the end it flows out of the system in Shangfanpu. Through the analyses of groundwater level data and hydrogeological drilling data, based on groundwater D and ^(18) O isotope test results, the karst groundwater circulation system in the northern basin of Laiyuan Spring area is further verified, which provides hydrogeological basis for water resources development and utilization as well as protection in this area.
基金Project(51308549)supported by the National Natural Science Foundation,China
文摘In order to study an isolation system of rolling friction with springs, computer programs were compiled to evaluate the seismic performance based on its movement characteristics. Through the programs, the influences of various seismic performance factors, e.g., rolling friction coefficient, spring constant, were systematically investigated. Results show that by increasing the rolling friction coefficient, the structural relative displacement due to seismic load effectively decreases, while the structural response magnitude varies mainly depending on the correlations between the following factors: the spring constant, the earthquake intensity, and the rolling friction coefficient. Furthermore, increasing the spring constant can decrease the structural relative displacement, as well as residual displacement, however, it increases the structural response magnitude. Finally, based on the analyses of various seismic performance factors subjected to the scenario earthquakes, optimized theoretical seismic performance can be achieved by reasonably combining the spring constant and the rolling friction coefficient.
