To ensure the operational safety of railways in the landslide-prone areas of mountainous regions,a large-scale model test and numerical simulation were conducted to study the bending moment distribution,internal force...To ensure the operational safety of railways in the landslide-prone areas of mountainous regions,a large-scale model test and numerical simulation were conducted to study the bending moment distribution,internal force distribution,deformation development,and crack propagation characteristics of a framed anti-sliding structure(FAS)under landslide thrust up to the point of failure.Results show that the maximum bending moment and its increase rate in the fore pile are greater than those in the rear pile,with the maximum bending moment of the fore pile approximately 1.1 times that of the rear pile.When the FAS fails,the displacement at the top of the fore pile is significantly greater,about 1.27 times that of the rear pile in the experiment.Major cracks develop at locations corresponding to the peak bending moments.Small transverse cracks initially appear on the upper surface at the intersection between the primary beam and rear pile and then spread to the side of the structure.At the failure stage,major cracks are observed at the pil-beam intersections and near the anchor points.Strengthening flexural stiffness at intersections where major cracks occur can improve the overall thrust-deformation coordination of the FAS,thereby maximizing its performance.展开更多
In order to find the main factors that influence the urban traffic structure,a relational model between the travelers＇ characteristics and the trip mode choice is built.The data of urban residents＇ characteristics a...In order to find the main factors that influence the urban traffic structure,a relational model between the travelers＇ characteristics and the trip mode choice is built.The data of urban residents＇ characteristics are obtained from statistical data,while the trip mode split data is collected through a trip survey in Bengbu.In addition,the discrete choice model is adopted to build the functional relationship between the mode choice and the travelers＇ personal characteristics,as well as family characteristics and trip characteristics.The model shows that the relationship between the mode split and the personal,as well as family and trip characteristics is stable and changes little as the time changes.Deduced by the discrete model,the mode split result is relatively accurate and can be feasibly used for trip mode structure forecasts.Furthermore,the proposed model can also contribute to find the key influencing factors on trip mode choice,and restructure or optimize the urban trip mode structure.展开更多
This paper aims to provide a decision-making method for the transportation management strategies in guiding the transformation of trip mode choice during planned special events. The Expo 2010 Shanghai is taken as an e...This paper aims to provide a decision-making method for the transportation management strategies in guiding the transformation of trip mode choice during planned special events. The Expo 2010 Shanghai is taken as an example, and a structural equation model is employed to analyze the dynamic mechanism of trip mode choice behavior and the effectiveness of the transportation management measures at different stages. Based on the difference between the objective-oriented stated preference （SP） survey results and the objectives, together with the feedback from the previous stage survey, some adjustments on the transportation management measures are made in the next stage of the planning process until the objectives are eventually achieved. The results indicate that the adjustments on transportation management measures at different stages can effectively raise the transit share to 88.6%. Nonlocal visitors are inclined to choose nonstop modes of transportation and the companion attributes have the most significant effects on the trip mode choices of visitors. The research method is proved to be an effective way to support the decision making process of transportation management measures during planned special events in the future.展开更多
To evaluate the responses of fixed and pinned pile groups under torsion, a method is presented to analyze the nonlinear behavior of free-standing pile groups with rigid pile caps. The method is capable of simulating t...To evaluate the responses of fixed and pinned pile groups under torsion, a method is presented to analyze the nonlinear behavior of free-standing pile groups with rigid pile caps. The method is capable of simulating the nonlinear soil response in the near field usingp-y and r-θ curves, the far-field interactions through Mindlin＇s and Randolph＇s elastic solutions, and the coupling effect of lateral resistance on torsional resistance of the individual piles using an empirical factor. Based on comparisons of the solutions for fixed- and pinned-head, 1×2, 2×2, and 3×3 pile groups subjected to torsion, it was found that pile-cap connection significantly influences the torsional capacity of pile groups and the assignment of applied torques in the pile groups. In this study, the applied torques for the pinned-head pile groups are only 44%-64% of those for the corresponding fixed-head pile groups at a twist angle of 2^o. Such a difference is mainly due to the change of the lateral resistances of individual piles in the groups.展开更多
Due to the unique structural mode and material property of a composite sandwich plate, related research such as fragment impact resistance of a composite mast is short of publication and urgent in this field. In this ...Due to the unique structural mode and material property of a composite sandwich plate, related research such as fragment impact resistance of a composite mast is short of publication and urgent in this field. In this paper, the commonly accepted sandwich core board theory was modified. Damage caused by a fragment attack was simulated onto a sandwich plate model built with solid and shell elements. It was shown that shear failure and vast matrix cracking are the main reasons for outer coat damage, and tension failure and partial matrix cracking are the cause for inner coat damage. Additionally, according to complexities in actual sea battles, different work conditions of missile attacks were set. Ballistic limit values of different fragment sizes were also obtained, which provides references for enhancing the fragment impact resistance of a composite mast.展开更多
As a typical tropical agro-forestry ecosystem in Wenchang, Hainan Province, China, rational mechanisms of the rubber-tea-chicken eco-agricultural model were studied with the Solow technological level index, stability ...As a typical tropical agro-forestry ecosystem in Wenchang, Hainan Province, China, rational mechanisms of the rubber-tea-chicken eco-agricultural model were studied with the Solow technological level index, stability indicator, harmonizing coefficient, grey corretation coefficient and production dominance. This study focused on rational hierarchical structure, the limiting factors and optimal strategies of the model development based on model structure, resource conditions and external market demands. Results showed that rational mechanism of the rubber-tea-chicken ecosystem model mainly included technological contributions, leverage function of dominance component （livestock husbandry）, stability of the model structure and harmony of its components, the model dominant product＇s market demand and government＇s supporting policies. The contributions of fund, technology, information and talent resources played an important role in improving sustainability and productivity of the agro-forestry model.展开更多
AIM： To analyze the polygraphic sleep patterns during cirrhosis progression in a rat model by repeated CCh administration. METHODS： Male Wistar rats received three weekly injections of CCl4 for 11 wk, and were analy...AIM： To analyze the polygraphic sleep patterns during cirrhosis progression in a rat model by repeated CCh administration. METHODS： Male Wistar rats received three weekly injections of CCl4 for 11 wk, and were analyzed before and during the induction of cirrhosis. Rats were im- planted with electrodes to record their sleep patterns. Polygraph recordings were made weekly over 11 wk for 8 h, during the light period. After a basal recording, rats received three weekly injections of CCl4. Histological confirmation of cirrhosis was performed after 11 wk. RESULTS： The results showed a progressive decrease in total wake time that reached statistical significance from the second week of treatment. In addition, there was an increase in total time of slow wave sleep （SWS）Ⅱ and rapid eye movement sleep （REM sleep） in most of the 11 wk. SWS I showed no significant variations. During the final weeks, a significant increase in REM sleep frequency was also observed. Histological analyses of the livers showed unequivocal signs of cirrhosis. CONCLUSION： These data suggest that hepatic failure produced by CCh administration is capable of modifying the sleep pattern even after only a few doses.展开更多
This paper is concerned with the hydroelastic problem of a very large pontoon-type floating structure(VLFS) edged with a pair of submerged horizontal plates, which is a combination of perforated and non-perforated pla...This paper is concerned with the hydroelastic problem of a very large pontoon-type floating structure(VLFS) edged with a pair of submerged horizontal plates, which is a combination of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. For the hydroelastic analysis, the fluid is assumed to be ideal and its motion is irrotational so that a velocity potential exists. The VLFS is modeled as an elastic plate according to the classical thin plate theory. The fluid-structure interaction problem is separated into conventional hydrodynamics and structure dynamics by using modal expansion method in the frequency-domain. It involves, firstly, the deflection of the VLFS, which is expressed by a superposition of modal functions and corresponding modal amplitudes. Then the boundary element method is used to solve the integral equations of diffraction and radiation on the body surface for the velocity potential, whereas the vibration equation is solved by the Galerkin's method for modal amplitudes, and then the deflection is obtained by the sum of multiplying modal functions with modal amplitudes. This study examines the effects of the width and location of the non-perforated horizontal plates on the hydroelastic response of the VLFS, then the performance of perforated plates is investigated to reduce the motion near the fore-end of the VLFS. Considering the advantages and disadvantages of submerged plates without and with cylindrical holes, we propose a simple anti-motion device, which is a combination of a pair of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. The effectiveness of this device in reducing the deformation and bending moment of the VLFS has been confirmed, and is compared with the results in cases without and with the submerged horizontal plates by the analysis in this paper.展开更多
In this study, taking cultivated land fertility evaluation data for example, we conducted a preliminary study of GIS theory and spatial data management, and construct the frame system of mobile structure based on the ...In this study, taking cultivated land fertility evaluation data for example, we conducted a preliminary study of GIS theory and spatial data management, and construct the frame system of mobile structure based on the three layer structure model of application layer, business logic layer and data layer. Then we established a spatial data storage model, which has unified the data standards and achieved the management of spatial data and attribute database. Taking ArcGIS API for iOS as GIS platform, Xcode as the tool, we have realized the functions of data integration, data query, data statistics and fertilization recommendation, and constructed the management and service platform of mobile fertilization expert system.展开更多
This article through to new embedded geriatric rehabilitation care development present situation, pointed out that in the popularization of its restriction factors, and then asked a further analysis of various factors...This article through to new embedded geriatric rehabilitation care development present situation, pointed out that in the popularization of its restriction factors, and then asked a further analysis of various factors, constructed the obstacle factors explanation structure model （ISM）.According to the result of classification model and find out the problem, the most direct factors and put forward the corresponding Suggestions, facilities for embedded geriatric rehabilitation nursing mode to find out the key points of development, provide a reference value to scientific basis.展开更多
A series of physical modelings in which a main roof is considered as a Kirchhoff plate supported or clammed by Winkler elastic foundation were performed to simulate the fracturing process of the main roof in longwall ...A series of physical modelings in which a main roof is considered as a Kirchhoff plate supported or clammed by Winkler elastic foundation were performed to simulate the fracturing process of the main roof in longwall mining. Based on these modelings spatial structures of the main roof after its fracture are described, blocks of the fractured main roof are classified and their behaviors are analyzed in this paper. Additionally, two stability indexes of the structures are defined, and the factors affecting stability of the structures with different boundaries and geometric conditions are discussed.展开更多
基金The National Natural Science Foundation of China(No.52078427).
文摘To ensure the operational safety of railways in the landslide-prone areas of mountainous regions,a large-scale model test and numerical simulation were conducted to study the bending moment distribution,internal force distribution,deformation development,and crack propagation characteristics of a framed anti-sliding structure(FAS)under landslide thrust up to the point of failure.Results show that the maximum bending moment and its increase rate in the fore pile are greater than those in the rear pile,with the maximum bending moment of the fore pile approximately 1.1 times that of the rear pile.When the FAS fails,the displacement at the top of the fore pile is significantly greater,about 1.27 times that of the rear pile in the experiment.Major cracks develop at locations corresponding to the peak bending moments.Small transverse cracks initially appear on the upper surface at the intersection between the primary beam and rear pile and then spread to the side of the structure.At the failure stage,major cracks are observed at the pil-beam intersections and near the anchor points.Strengthening flexural stiffness at intersections where major cracks occur can improve the overall thrust-deformation coordination of the FAS,thereby maximizing its performance.
基金The National Natural Science Foundation of China (No.50738001,51078086)
文摘In order to find the main factors that influence the urban traffic structure,a relational model between the travelers＇ characteristics and the trip mode choice is built.The data of urban residents＇ characteristics are obtained from statistical data,while the trip mode split data is collected through a trip survey in Bengbu.In addition,the discrete choice model is adopted to build the functional relationship between the mode choice and the travelers＇ personal characteristics,as well as family characteristics and trip characteristics.The model shows that the relationship between the mode split and the personal,as well as family and trip characteristics is stable and changes little as the time changes.Deduced by the discrete model,the mode split result is relatively accurate and can be feasibly used for trip mode structure forecasts.Furthermore,the proposed model can also contribute to find the key influencing factors on trip mode choice,and restructure or optimize the urban trip mode structure.
基金The National Natural Science Foundation of China(No.51278363)
文摘This paper aims to provide a decision-making method for the transportation management strategies in guiding the transformation of trip mode choice during planned special events. The Expo 2010 Shanghai is taken as an example, and a structural equation model is employed to analyze the dynamic mechanism of trip mode choice behavior and the effectiveness of the transportation management measures at different stages. Based on the difference between the objective-oriented stated preference （SP） survey results and the objectives, together with the feedback from the previous stage survey, some adjustments on the transportation management measures are made in the next stage of the planning process until the objectives are eventually achieved. The results indicate that the adjustments on transportation management measures at different stages can effectively raise the transit share to 88.6%. Nonlocal visitors are inclined to choose nonstop modes of transportation and the companion attributes have the most significant effects on the trip mode choices of visitors. The research method is proved to be an effective way to support the decision making process of transportation management measures during planned special events in the future.
基金Project (No. HKUST 6037/01E) supported by the Research GrantsCouncil of Hong Kong SAR, China
文摘To evaluate the responses of fixed and pinned pile groups under torsion, a method is presented to analyze the nonlinear behavior of free-standing pile groups with rigid pile caps. The method is capable of simulating the nonlinear soil response in the near field usingp-y and r-θ curves, the far-field interactions through Mindlin＇s and Randolph＇s elastic solutions, and the coupling effect of lateral resistance on torsional resistance of the individual piles using an empirical factor. Based on comparisons of the solutions for fixed- and pinned-head, 1×2, 2×2, and 3×3 pile groups subjected to torsion, it was found that pile-cap connection significantly influences the torsional capacity of pile groups and the assignment of applied torques in the pile groups. In this study, the applied torques for the pinned-head pile groups are only 44%-64% of those for the corresponding fixed-head pile groups at a twist angle of 2^o. Such a difference is mainly due to the change of the lateral resistances of individual piles in the groups.
基金Supported by the Research-in-advance Foundation of Naval Armory under Grant No.401030101the National Defense Science and Technology Cooperation Foundation(2007DFR80340)Research-in-advance Foundation of National Defense Science and Technology in Shipbuilding Industry(07J1.1.6)
文摘Due to the unique structural mode and material property of a composite sandwich plate, related research such as fragment impact resistance of a composite mast is short of publication and urgent in this field. In this paper, the commonly accepted sandwich core board theory was modified. Damage caused by a fragment attack was simulated onto a sandwich plate model built with solid and shell elements. It was shown that shear failure and vast matrix cracking are the main reasons for outer coat damage, and tension failure and partial matrix cracking are the cause for inner coat damage. Additionally, according to complexities in actual sea battles, different work conditions of missile attacks were set. Ballistic limit values of different fragment sizes were also obtained, which provides references for enhancing the fragment impact resistance of a composite mast.
基金funded by National Natural Science Foundation of China(Grant No.40971227)International science & Technology Cooperation Program of China (Grant No.2010DFA21880)China Postdoctoral Science Foundation
文摘As a typical tropical agro-forestry ecosystem in Wenchang, Hainan Province, China, rational mechanisms of the rubber-tea-chicken eco-agricultural model were studied with the Solow technological level index, stability indicator, harmonizing coefficient, grey corretation coefficient and production dominance. This study focused on rational hierarchical structure, the limiting factors and optimal strategies of the model development based on model structure, resource conditions and external market demands. Results showed that rational mechanism of the rubber-tea-chicken ecosystem model mainly included technological contributions, leverage function of dominance component （livestock husbandry）, stability of the model structure and harmony of its components, the model dominant product＇s market demand and government＇s supporting policies. The contributions of fund, technology, information and talent resources played an important role in improving sustainability and productivity of the agro-forestry model.
基金Supported by Grant 50633 from CONACyT to Jiménez-Anguiano A
文摘AIM： To analyze the polygraphic sleep patterns during cirrhosis progression in a rat model by repeated CCh administration. METHODS： Male Wistar rats received three weekly injections of CCl4 for 11 wk, and were analyzed before and during the induction of cirrhosis. Rats were im- planted with electrodes to record their sleep patterns. Polygraph recordings were made weekly over 11 wk for 8 h, during the light period. After a basal recording, rats received three weekly injections of CCl4. Histological confirmation of cirrhosis was performed after 11 wk. RESULTS： The results showed a progressive decrease in total wake time that reached statistical significance from the second week of treatment. In addition, there was an increase in total time of slow wave sleep （SWS）Ⅱ and rapid eye movement sleep （REM sleep） in most of the 11 wk. SWS I showed no significant variations. During the final weeks, a significant increase in REM sleep frequency was also observed. Histological analyses of the livers showed unequivocal signs of cirrhosis. CONCLUSION： These data suggest that hepatic failure produced by CCh administration is capable of modifying the sleep pattern even after only a few doses.
基金the National Science Foundation for Creative Re-search Groups of China (Grant No.50921001) for supporting this work
文摘This paper is concerned with the hydroelastic problem of a very large pontoon-type floating structure(VLFS) edged with a pair of submerged horizontal plates, which is a combination of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. For the hydroelastic analysis, the fluid is assumed to be ideal and its motion is irrotational so that a velocity potential exists. The VLFS is modeled as an elastic plate according to the classical thin plate theory. The fluid-structure interaction problem is separated into conventional hydrodynamics and structure dynamics by using modal expansion method in the frequency-domain. It involves, firstly, the deflection of the VLFS, which is expressed by a superposition of modal functions and corresponding modal amplitudes. Then the boundary element method is used to solve the integral equations of diffraction and radiation on the body surface for the velocity potential, whereas the vibration equation is solved by the Galerkin's method for modal amplitudes, and then the deflection is obtained by the sum of multiplying modal functions with modal amplitudes. This study examines the effects of the width and location of the non-perforated horizontal plates on the hydroelastic response of the VLFS, then the performance of perforated plates is investigated to reduce the motion near the fore-end of the VLFS. Considering the advantages and disadvantages of submerged plates without and with cylindrical holes, we propose a simple anti-motion device, which is a combination of a pair of perforated and non-perforated plates attached to the for-end and back-end of the VLFS. The effectiveness of this device in reducing the deformation and bending moment of the VLFS has been confirmed, and is compared with the results in cases without and with the submerged horizontal plates by the analysis in this paper.
文摘In this study, taking cultivated land fertility evaluation data for example, we conducted a preliminary study of GIS theory and spatial data management, and construct the frame system of mobile structure based on the three layer structure model of application layer, business logic layer and data layer. Then we established a spatial data storage model, which has unified the data standards and achieved the management of spatial data and attribute database. Taking ArcGIS API for iOS as GIS platform, Xcode as the tool, we have realized the functions of data integration, data query, data statistics and fertilization recommendation, and constructed the management and service platform of mobile fertilization expert system.
文摘This article through to new embedded geriatric rehabilitation care development present situation, pointed out that in the popularization of its restriction factors, and then asked a further analysis of various factors, constructed the obstacle factors explanation structure model （ISM）.According to the result of classification model and find out the problem, the most direct factors and put forward the corresponding Suggestions, facilities for embedded geriatric rehabilitation nursing mode to find out the key points of development, provide a reference value to scientific basis.
文摘A series of physical modelings in which a main roof is considered as a Kirchhoff plate supported or clammed by Winkler elastic foundation were performed to simulate the fracturing process of the main roof in longwall mining. Based on these modelings spatial structures of the main roof after its fracture are described, blocks of the fractured main roof are classified and their behaviors are analyzed in this paper. Additionally, two stability indexes of the structures are defined, and the factors affecting stability of the structures with different boundaries and geometric conditions are discussed.
