采用座逾渗模型,引入计算机控制扫描电镜(computer-controlled scanning electron microscope,CCSEM)矿物原粒径数据作模型初始矿物数据,考察了不同孔隙分布对煤焦转化与破碎的影响,煤焦转化过程对破碎程度的影响,以及煤焦破碎和内在矿...采用座逾渗模型,引入计算机控制扫描电镜(computer-controlled scanning electron microscope,CCSEM)矿物原粒径数据作模型初始矿物数据,考察了不同孔隙分布对煤焦转化与破碎的影响,煤焦转化过程对破碎程度的影响,以及煤焦破碎和内在矿聚合对飞灰颗粒物尤其是1～10μm颗粒物最终分布的影响。模拟结果表明:煤焦初始孔隙率越大,表面反应面积和破碎次数均越大。当φ≥0.4时,煤焦破碎明显集中于转化率为0.4～0.7的阶段,且峰值有一定的向转化前期移动的趋势。初始孔隙率φ越大,颗粒破碎就越剧烈,内在矿聚合概率小,10μm以内颗粒物的数目明显增大。随着φ值的增大,生成颗粒物的浓度尤其是1～10μm颗粒物的浓度逐渐升高,最终颗粒物浓度分布到在3～5μm和6～8μm存在2个峰值,这与实际燃烧生成的中间模态和粗模态颗粒物的峰值基本吻合。展开更多
In order to improve the computation efficiency and simulation accuracy,a novel simplified simulation method for friction pendulum bearing( FPB) is proposed. The behavior of FPB was analyzed based on the stress charact...In order to improve the computation efficiency and simulation accuracy,a novel simplified simulation method for friction pendulum bearing( FPB) is proposed. The behavior of FPB was analyzed based on the stress characteristics of the slider of FPB. Then,a novel simplified FPB model with a single pendulum and a nonlinear spring was established. The mechanical behavior of the simplified model was analyzed and it conformed well to the basic requirements of FPB. Furthermore,shaking table tests of a concrete slab block structure isolated by four FPBs were carried out, followed by finite element simulations of the test using the proposed simplified model.Three waves and eleven loading scenarios were selected in the test. The results show that the overall trend of the relative displacement time-history curves,the horizontal acceleration time-history curves and the vertical acceleration time-history curves from the numerical simulation match in a good manner with those obtained from the tests. Specifically,it is found that the difference of the peak value within these curves between the simulation and test results is less than 15%,which means that the proposed simplified model can be used to simulate the FPB behaviors under dynamic loadings with acceptable accuracy for engineering purposes.展开更多
The linear seat suspension is considered due to the low cost consideration therefore, the optimal linear seat suspension design method can be used for this purpose. In this paper, the design of a passive vehicle seat ...The linear seat suspension is considered due to the low cost consideration therefore, the optimal linear seat suspension design method can be used for this purpose. In this paper, the design of a passive vehicle seat suspension system was handled in the framework of linear optimization. The variance of the dynamic load resulting from the vibrating vehicle operating at a constant speed was used as the performance measure of a suspension system. Using 4-DOF human body model developed by Abbas et al., with linear seat suspension and coupled with half car model. A genetic algorithm is applied to solve the linear optimization problem. The optimal design parameters of the seat suspension systems obtained are kse = 3 012.5 N/m and cse = 1 210.4 N.s/m, respectively.展开更多
Bianchi type I string dust cosmological models in the presence and absence of magnetic field in the frame work of Lyra geometry are investigated. To get the deterministic model of the universe, we assume that the eige...Bianchi type I string dust cosmological models in the presence and absence of magnetic field in the frame work of Lyra geometry are investigated. To get the deterministic model of the universe, we assume that the eigenvalue （σ^11） of shear tensor （σ^ii） is proportional to expansion （θ）. This leads to A = （BC）^n, where A, B, C are metric potentials and n is a constant. To discuss the results in terms of cosmic time t, we have considered n = 1. The physical and geometrical aspects＇ of the models and singularities in the models are also discussed.展开更多
Involvement in road traffic crashes as vehicle occupants is a leading cause of death and serious injury among children. The objective of this study was to investigate crash severity factors and child safety restraint ...Involvement in road traffic crashes as vehicle occupants is a leading cause of death and serious injury among children. The objective of this study was to investigate crash severity factors and child safety restraint use characteristics in order to identify effective countermeasures to increase children＇s highway safety. Characteristics and percentages of restraint use among child passengers aged 4-13 years were examined using highway crash data from Kansas. The association between restraint use, injury severity and characteristics of children involved in crashes were investigated using OR （odds ratios） and a logistic regression model, which was used to identify risk factors. Results showed that children, who were unrestrained, were seated in the front seat, traveling with drunk drivers and on rural roads, and traveling during nighttime was more vulnerable to severe injury in the case of motor vehicle crashes. The most frequent contributing causes related to crashes involving children included driver＇s inattention while driving, failure to yield right-of-way, driving too fast, wet roads and animals in the road. Based on identified critical factors, general countermeasure ideas to improve children＇s traffic safety were suggested, including age-appropriate and size-appropriate seat belt restraints and having children seated in the rear seat. Parents and children must gain better education regarding these safety measures in order to increase child safety on the road.展开更多
The authors describe the relationships between categories of B-branes in dif- ferent phases of the non-Abelian gauged linear sigma model. The relationship is described explicitly for the model proposed by Hori and Ton...The authors describe the relationships between categories of B-branes in dif- ferent phases of the non-Abelian gauged linear sigma model. The relationship is described explicitly for the model proposed by Hori and Tong with non-Abelian gauge group that connects two non-birational Calabi-Yau varieties studied by Rcdland. A grade restriction rule for this model is derived using the hemisphere partition function and it is used to map B-type D-branes between the two Calabi-Yau varieties.展开更多
文摘采用座逾渗模型,引入计算机控制扫描电镜(computer-controlled scanning electron microscope,CCSEM)矿物原粒径数据作模型初始矿物数据,考察了不同孔隙分布对煤焦转化与破碎的影响,煤焦转化过程对破碎程度的影响,以及煤焦破碎和内在矿聚合对飞灰颗粒物尤其是1～10μm颗粒物最终分布的影响。模拟结果表明:煤焦初始孔隙率越大,表面反应面积和破碎次数均越大。当φ≥0.4时,煤焦破碎明显集中于转化率为0.4～0.7的阶段,且峰值有一定的向转化前期移动的趋势。初始孔隙率φ越大,颗粒破碎就越剧烈,内在矿聚合概率小,10μm以内颗粒物的数目明显增大。随着φ值的增大,生成颗粒物的浓度尤其是1～10μm颗粒物的浓度逐渐升高,最终颗粒物浓度分布到在3～5μm和6～8μm存在2个峰值,这与实际燃烧生成的中间模态和粗模态颗粒物的峰值基本吻合。
基金The National Natural Science Foundation of China(No.6505000184)the National Key Research and Development Program of China(No.2016YFC0701400)
文摘In order to improve the computation efficiency and simulation accuracy,a novel simplified simulation method for friction pendulum bearing( FPB) is proposed. The behavior of FPB was analyzed based on the stress characteristics of the slider of FPB. Then,a novel simplified FPB model with a single pendulum and a nonlinear spring was established. The mechanical behavior of the simplified model was analyzed and it conformed well to the basic requirements of FPB. Furthermore,shaking table tests of a concrete slab block structure isolated by four FPBs were carried out, followed by finite element simulations of the test using the proposed simplified model.Three waves and eleven loading scenarios were selected in the test. The results show that the overall trend of the relative displacement time-history curves,the horizontal acceleration time-history curves and the vertical acceleration time-history curves from the numerical simulation match in a good manner with those obtained from the tests. Specifically,it is found that the difference of the peak value within these curves between the simulation and test results is less than 15%,which means that the proposed simplified model can be used to simulate the FPB behaviors under dynamic loadings with acceptable accuracy for engineering purposes.
文摘The linear seat suspension is considered due to the low cost consideration therefore, the optimal linear seat suspension design method can be used for this purpose. In this paper, the design of a passive vehicle seat suspension system was handled in the framework of linear optimization. The variance of the dynamic load resulting from the vibrating vehicle operating at a constant speed was used as the performance measure of a suspension system. Using 4-DOF human body model developed by Abbas et al., with linear seat suspension and coupled with half car model. A genetic algorithm is applied to solve the linear optimization problem. The optimal design parameters of the seat suspension systems obtained are kse = 3 012.5 N/m and cse = 1 210.4 N.s/m, respectively.
文摘Bianchi type I string dust cosmological models in the presence and absence of magnetic field in the frame work of Lyra geometry are investigated. To get the deterministic model of the universe, we assume that the eigenvalue （σ^11） of shear tensor （σ^ii） is proportional to expansion （θ）. This leads to A = （BC）^n, where A, B, C are metric potentials and n is a constant. To discuss the results in terms of cosmic time t, we have considered n = 1. The physical and geometrical aspects＇ of the models and singularities in the models are also discussed.
文摘Involvement in road traffic crashes as vehicle occupants is a leading cause of death and serious injury among children. The objective of this study was to investigate crash severity factors and child safety restraint use characteristics in order to identify effective countermeasures to increase children＇s highway safety. Characteristics and percentages of restraint use among child passengers aged 4-13 years were examined using highway crash data from Kansas. The association between restraint use, injury severity and characteristics of children involved in crashes were investigated using OR （odds ratios） and a logistic regression model, which was used to identify risk factors. Results showed that children, who were unrestrained, were seated in the front seat, traveling with drunk drivers and on rural roads, and traveling during nighttime was more vulnerable to severe injury in the case of motor vehicle crashes. The most frequent contributing causes related to crashes involving children included driver＇s inattention while driving, failure to yield right-of-way, driving too fast, wet roads and animals in the road. Based on identified critical factors, general countermeasure ideas to improve children＇s traffic safety were suggested, including age-appropriate and size-appropriate seat belt restraints and having children seated in the rear seat. Parents and children must gain better education regarding these safety measures in order to increase child safety on the road.
文摘The authors describe the relationships between categories of B-branes in dif- ferent phases of the non-Abelian gauged linear sigma model. The relationship is described explicitly for the model proposed by Hori and Tong with non-Abelian gauge group that connects two non-birational Calabi-Yau varieties studied by Rcdland. A grade restriction rule for this model is derived using the hemisphere partition function and it is used to map B-type D-branes between the two Calabi-Yau varieties.
