The safety and the fatigue comfort were compared between a domestic and a Japanese postal bicycle. Firstly, the fatigue comfort of these two kinds of bicycles was evaluated by surface electromyographic signal (sEMG) e...The safety and the fatigue comfort were compared between a domestic and a Japanese postal bicycle. Firstly, the fatigue comfort of these two kinds of bicycles was evaluated by surface electromyographic signal (sEMG) experiment, in which human lower limb muscle groups were research objects, and the average EMG (AEMG) index and median frequency (MF) were chosen as the evaluation indexes. Secondly, the safety of these two kinds of bicycle frames was analyzed and compared by using the finite element analysis. The results show that the riding fatigue comfort of the Japanese postal bicycle is better, and the Japanese postal bicycle frame is more safe and reasonable although both the postal bicycles meet the requirement for strength. Finally, based on the above analysis, the frame structure and related parameters of the domestic postal bicycle were improved with reference to the Japanese postal bicycle and biomechanics theory.展开更多
Estimation of support pressure is extremely important to the support system design and the construction safety of tunnels.At present,there are many methods for the estimation of support pressure based on different roc...Estimation of support pressure is extremely important to the support system design and the construction safety of tunnels.At present,there are many methods for the estimation of support pressure based on different rock mass classification systems,such as Q system,GSI system and RMR system.However,various rock mass classification systems are based on different tunnel geologic conditions in various regions.Therefore,each rock mass classification system has a certain regionality.In China,the BQ-Inex(BQ system)has been widely used in the field of rock engineering ever since its development.Unfortunately,there is still no estimation method of support pressure with BQ-index as parameters.Based on the field test data from 54 tunnels in China,a new empirical method considering BQ-Inex,tunnel span and rock weight is proposed to estimate the support pressure using multiple nonlinear regression analysis methods.And then the significance and necessity of support pressure estimation method for the safety of tunnel construction in China is explained through the comparison and analysis with the existing internationally widely used support pressure estimation methods of RMR system,Q system and GSI system.Finally,the empirical method of estimating the support pressure based on BQ-index was applied to designing the support system in the China’s high-speed railway tunnel—Zhengwan high-speed railway and the rationality of this method has been verified through the data of field test.展开更多
Purpose： This study aimed to examine the extent to which the quality physical education teaching （QPET） practices contributed to improving 4th- and 5th-grade students＇ manipulative skill competency. Methods： Part...Purpose： This study aimed to examine the extent to which the quality physical education teaching （QPET） practices contributed to improving 4th- and 5th-grade students＇ manipulative skill competency. Methods： Participants were 9 elementary physical education （PE） teachers and their 4th- and 5th-grade students （n = 2709 3420）. The students＇ skill competency was assessed with 3 manipulative skills using PE metrics assessment rubrics. The PE teachers＇ levels of QPET were assessed by coding 63 videotaped lessons using the assessing quality teaching rubrics （AQTR）, which consisted of 4 essential dimensions including task design, task presentation, class management, and instructional guidance. Codes were confirmed through inter-rater reliability （82.4%, 84.5%, and 94%）. Data were analyzed through descriptive statistics, multiple R2 regression models, and independent sample t tests. Results： This study indicated that the 4 essential dimensions of QPET were all significant contributors to students＇ manipulative skill competency. These predictors were significantly higher for boys than for girls in soccer and striking skills, while they were significantly higher for girls than for boys in throwing skill competency. Of the 4 essential dimensions of QPET, task presentation played the most significant role in contributing to all 3 skill competencies for both boys and girls. Further, students who experienced high QPET were significantly more skillfully competent than those students who did not have this experience. Conclusion： It was concluded that the QPET practices played a significantly critical role in contributing to students＇ manipulative skill competency.展开更多
According to the characteristics of ecosystem and concept of the ecosystem in mining area, the index system of the ecosystem health in mining area was set up, and the evaluation standard was established. Aiming at the...According to the characteristics of ecosystem and concept of the ecosystem in mining area, the index system of the ecosystem health in mining area was set up, and the evaluation standard was established. Aiming at the complexion in which the information lost in index ration, the matter element method was put forward to evaluate the ecosystem health in mining area. Making use of the model set up, the weight was built up by the method of index number heavy, the matter element, clas- sical field, and limit field were set up. The rating hierarchy was calculated by relating function. As a case study in the mining area of Pingyangsi Town, the results show that the ecosystem is good and sustainable from 2003 to 2006, but the healthy degree is not high, and some indexes have depravation.展开更多
Industrial ecological system is a sustainable mode of modern industry development. Industrial symbiosis, a sub-field of industrial ecology, engages traditionally separate industries in a collective approach, involving...Industrial ecological system is a sustainable mode of modern industry development. Industrial symbiosis, a sub-field of industrial ecology, engages traditionally separate industries in a collective approach, involving exchange of materials, energy, water, and/or by-products, to enhance competitive ability and environmental performance. To construct a symbiosis analysis method, this article employs a number of parameters embodying information about materials, energy and economics as the main essential parameters in system analysis and introduces symbiosis profit and symbiotic consumption elements as the economic indicators. A modeling and simulation program is designed using the agent-based modeling approach to simulate the evolvement of a hypothetical coal-based industrial system and the change of symbiosis conditions in the process of construction is examined. The simulation program built using the Swarm library, which is a freely available multi-agent simulation package, provides a useful demonstration for the symbiosis analysis method.展开更多
With the development of high-speed and heavy-haul railway in China, problems like insufficient thickness of ballast bed and overlarge track stiffness are obvious. Ballast may break into small particles and their conta...With the development of high-speed and heavy-haul railway in China, problems like insufficient thickness of ballast bed and overlarge track stiffness are obvious. Ballast may break into small particles and their contact status will deteriorate under cyclic loading, resulting in ballast degradation. Discrete element method(DEM) was used to research improved performance of ballast bed using elastic sleeper. Clusters were generated by bonding spheres to model real ballasts, while broken bonds were utilized to distinguish breakage. Two kinds of ballast beds with elastic sleeper and conventional sleeper were established, respectively. After applying cyclic loading to the models, differences of mechanical properties between two models were analyzed by contrasting their dynamic behavior indexes, such as particle contact force, sleeper settlement, vibration velocity and acceleration, breakage characteristic. The results illustrate that compared with conventional sleeper, elastic sleeper increases sleeper settlement, while reduces ballast vibration and contact force between particles, which could depress ballast breakage.展开更多
There are essentially six sources for obsidians in the Mediterranean Basin： Mount Arci in Sardinia, the islands of Lipari and Pantelleria in Sicily and Palmarola in Latium, as well as the islands of Melos and Gyali i...There are essentially six sources for obsidians in the Mediterranean Basin： Mount Arci in Sardinia, the islands of Lipari and Pantelleria in Sicily and Palmarola in Latium, as well as the islands of Melos and Gyali in the south-eastern part of Greece. Identification and quantification of principal and trace elements which compose this volcanic glass allow source tracking. The present study proposes a investigation methodology, which was developed on a sample set composed by archaeological obsidian findings from Neolithic sites in Latium; three different analytical techniques are compared： SEM-EDXS, ED-XRF and LA-ICP-MS, in order to gather a wide data set to be compared with data in literature and to be processed by Principal Component Analysis （PCA） for assigning a provenance to each find.展开更多
The deformation performance index limits of high reinforced concrete （RC） shear wall components based on Chinese codes were discussed by the nonlinear finite element method. Two typical RC shear wall specimens in th...The deformation performance index limits of high reinforced concrete （RC） shear wall components based on Chinese codes were discussed by the nonlinear finite element method. Two typical RC shear wall specimens in the previous work were first used to verify the correctness of the nonlinear finite element method. Then, the nonlinear finite element method was applied to study the deformability of a set of high RC shear wall components designed according to current Chinese codes and with shear span ratio λ≥2.0. Parametric studies were made on the influence of shear span ratio, axial compression ratio, ratio of flexural capacity to shear capacity and main flexural reinforcement ratio of confined botmdary members. Finally, the deformation performance index and its limits of high RC shear wall components under severe earthquakes were proposed by the finite element model results, which offers a reference in determining the performance status of RC shear wall components designed based on Chinese codes.展开更多
基金Supported by Special Fund Project for Technology Innovation of Tianjin (No.10FDZDGX00500)Tianjin Product Quality Inspection Technology Research Institute
文摘The safety and the fatigue comfort were compared between a domestic and a Japanese postal bicycle. Firstly, the fatigue comfort of these two kinds of bicycles was evaluated by surface electromyographic signal (sEMG) experiment, in which human lower limb muscle groups were research objects, and the average EMG (AEMG) index and median frequency (MF) were chosen as the evaluation indexes. Secondly, the safety of these two kinds of bicycle frames was analyzed and compared by using the finite element analysis. The results show that the riding fatigue comfort of the Japanese postal bicycle is better, and the Japanese postal bicycle frame is more safe and reasonable although both the postal bicycles meet the requirement for strength. Finally, based on the above analysis, the frame structure and related parameters of the domestic postal bicycle were improved with reference to the Japanese postal bicycle and biomechanics theory.
基金Projects(51878567,51878568,51578458)supported by the National Natural Science Foundation of ChinaProjects(2017G007-F,2017G007-H)supported by China Railway Science and Technology Research and Development Plan。
文摘Estimation of support pressure is extremely important to the support system design and the construction safety of tunnels.At present,there are many methods for the estimation of support pressure based on different rock mass classification systems,such as Q system,GSI system and RMR system.However,various rock mass classification systems are based on different tunnel geologic conditions in various regions.Therefore,each rock mass classification system has a certain regionality.In China,the BQ-Inex(BQ system)has been widely used in the field of rock engineering ever since its development.Unfortunately,there is still no estimation method of support pressure with BQ-index as parameters.Based on the field test data from 54 tunnels in China,a new empirical method considering BQ-Inex,tunnel span and rock weight is proposed to estimate the support pressure using multiple nonlinear regression analysis methods.And then the significance and necessity of support pressure estimation method for the safety of tunnel construction in China is explained through the comparison and analysis with the existing internationally widely used support pressure estimation methods of RMR system,Q system and GSI system.Finally,the empirical method of estimating the support pressure based on BQ-index was applied to designing the support system in the China’s high-speed railway tunnel—Zhengwan high-speed railway and the rationality of this method has been verified through the data of field test.
文摘Purpose： This study aimed to examine the extent to which the quality physical education teaching （QPET） practices contributed to improving 4th- and 5th-grade students＇ manipulative skill competency. Methods： Participants were 9 elementary physical education （PE） teachers and their 4th- and 5th-grade students （n = 2709 3420）. The students＇ skill competency was assessed with 3 manipulative skills using PE metrics assessment rubrics. The PE teachers＇ levels of QPET were assessed by coding 63 videotaped lessons using the assessing quality teaching rubrics （AQTR）, which consisted of 4 essential dimensions including task design, task presentation, class management, and instructional guidance. Codes were confirmed through inter-rater reliability （82.4%, 84.5%, and 94%）. Data were analyzed through descriptive statistics, multiple R2 regression models, and independent sample t tests. Results： This study indicated that the 4 essential dimensions of QPET were all significant contributors to students＇ manipulative skill competency. These predictors were significantly higher for boys than for girls in soccer and striking skills, while they were significantly higher for girls than for boys in throwing skill competency. Of the 4 essential dimensions of QPET, task presentation played the most significant role in contributing to all 3 skill competencies for both boys and girls. Further, students who experienced high QPET were significantly more skillfully competent than those students who did not have this experience. Conclusion： It was concluded that the QPET practices played a significantly critical role in contributing to students＇ manipulative skill competency.
文摘According to the characteristics of ecosystem and concept of the ecosystem in mining area, the index system of the ecosystem health in mining area was set up, and the evaluation standard was established. Aiming at the complexion in which the information lost in index ration, the matter element method was put forward to evaluate the ecosystem health in mining area. Making use of the model set up, the weight was built up by the method of index number heavy, the matter element, clas- sical field, and limit field were set up. The rating hierarchy was calculated by relating function. As a case study in the mining area of Pingyangsi Town, the results show that the ecosystem is good and sustainable from 2003 to 2006, but the healthy degree is not high, and some indexes have depravation.
基金Supported by the National Basic Research Program of China(2012CB720500)the National Natural Science Foundation of China(20936004)
文摘Industrial ecological system is a sustainable mode of modern industry development. Industrial symbiosis, a sub-field of industrial ecology, engages traditionally separate industries in a collective approach, involving exchange of materials, energy, water, and/or by-products, to enhance competitive ability and environmental performance. To construct a symbiosis analysis method, this article employs a number of parameters embodying information about materials, energy and economics as the main essential parameters in system analysis and introduces symbiosis profit and symbiotic consumption elements as the economic indicators. A modeling and simulation program is designed using the agent-based modeling approach to simulate the evolvement of a hypothetical coal-based industrial system and the change of symbiosis conditions in the process of construction is examined. The simulation program built using the Swarm library, which is a freely available multi-agent simulation package, provides a useful demonstration for the symbiosis analysis method.
基金Project(U1234211)supported by the National Natural Science Foundation of ChinaProject(2013G009-B)supported by China Railway Corporation
文摘With the development of high-speed and heavy-haul railway in China, problems like insufficient thickness of ballast bed and overlarge track stiffness are obvious. Ballast may break into small particles and their contact status will deteriorate under cyclic loading, resulting in ballast degradation. Discrete element method(DEM) was used to research improved performance of ballast bed using elastic sleeper. Clusters were generated by bonding spheres to model real ballasts, while broken bonds were utilized to distinguish breakage. Two kinds of ballast beds with elastic sleeper and conventional sleeper were established, respectively. After applying cyclic loading to the models, differences of mechanical properties between two models were analyzed by contrasting their dynamic behavior indexes, such as particle contact force, sleeper settlement, vibration velocity and acceleration, breakage characteristic. The results illustrate that compared with conventional sleeper, elastic sleeper increases sleeper settlement, while reduces ballast vibration and contact force between particles, which could depress ballast breakage.
文摘There are essentially six sources for obsidians in the Mediterranean Basin： Mount Arci in Sardinia, the islands of Lipari and Pantelleria in Sicily and Palmarola in Latium, as well as the islands of Melos and Gyali in the south-eastern part of Greece. Identification and quantification of principal and trace elements which compose this volcanic glass allow source tracking. The present study proposes a investigation methodology, which was developed on a sample set composed by archaeological obsidian findings from Neolithic sites in Latium; three different analytical techniques are compared： SEM-EDXS, ED-XRF and LA-ICP-MS, in order to gather a wide data set to be compared with data in literature and to be processed by Principal Component Analysis （PCA） for assigning a provenance to each find.
基金Project(2009ZA04) supported by the Independent Research Foundation of State Key Laboratory of Subtropical Architecture Science,China
文摘The deformation performance index limits of high reinforced concrete （RC） shear wall components based on Chinese codes were discussed by the nonlinear finite element method. Two typical RC shear wall specimens in the previous work were first used to verify the correctness of the nonlinear finite element method. Then, the nonlinear finite element method was applied to study the deformability of a set of high RC shear wall components designed according to current Chinese codes and with shear span ratio λ≥2.0. Parametric studies were made on the influence of shear span ratio, axial compression ratio, ratio of flexural capacity to shear capacity and main flexural reinforcement ratio of confined botmdary members. Finally, the deformation performance index and its limits of high RC shear wall components under severe earthquakes were proposed by the finite element model results, which offers a reference in determining the performance status of RC shear wall components designed based on Chinese codes.
