This study aims at investigating the effect of using L 1 （Arabic Language） while teaching a target language （English Language） on the achievement in General English of foundation year students in King Abdulaziz Un...This study aims at investigating the effect of using L 1 （Arabic Language） while teaching a target language （English Language） on the achievement in General English of foundation year students in King Abdulaziz University. To achieve the purpose of the study, the researcher used an experimental design： an experimental group and a control group. The independent variable is using L1 while teaching English in very limited and specified areas. The dependent variable is students＇ achievement in general English. The statistics used is the t-test. The population of the study was all students enrolled in the foundation year 1431/1432 in the ELI （English Language Institute） at King Abdulaziz University. The sample of the study consisted of 50 students taking North Star in the sections A and B as a university requirement in the foundation year 1431/1432 in King Abdulaziz University. The results of the study were in favor of banning Arabic in the English language classroom as shown in the mean scores of the control and experimental groups in the tables. It is recommended that teachers and instructors should be trained to use teaching strategies that help them use English only in the English language classroom.展开更多
A two-dimensionM discrete element code, particle flow code （PFC2D）, is employed to investigate foundations reinforced with horizontal-vertical （H-V） inclusions. The initial states and loading processes of both unr...A two-dimensionM discrete element code, particle flow code （PFC2D）, is employed to investigate foundations reinforced with horizontal-vertical （H-V） inclusions. The initial states and loading processes of both unreinforced and H-V reinforced foundations are simulated by PFC2D method. The interface between particles and reinforcements, and the reinforcement mechanism of the H-V reinforced foundations are studied through stress distribution graphs, displacement vector graphs and contact force graphs. The simulation results demonstrate that the vertical elements of the H-V reinforcement keep the particles from being displaced under the applied load. The H-V reinforcement can distribute the load uniformly over a wider area, thereby improving the bearing capacity of soil foundation.展开更多
Since collapsible soils are been mostly transported by wind and deposited in arid or semi-arid regions, they founded in a state of unsaturated condition. In addition, engineering filling when placed in a certain none ...Since collapsible soils are been mostly transported by wind and deposited in arid or semi-arid regions, they founded in a state of unsaturated condition. In addition, engineering filling when placed in a certain none want density, undesired settlement will be predictable either due to wetting or due to loading on these soil deposits. Collapsibility study is important for the foundation design and construction on these soils. The most foundation systems used on these soils are isolated and strip footing connected with concrete tie beams. Therefore studying rigid foundation system resting on partially saturated collapsible soil/deposits is very imp</span><span style="font-family:Verdana;">o</span><span style="font-family:Verdana;">rtant. The present work investigated using rigid strip footing resting in collapsible soils to study the effect of stress interference due to progressive wetting depth from leakage of surface water on collapsibility settlement. The study has been investigated the influence of different behavior of strip footing and inverted T-section strip footing rigidity system resting on unsaturated soil by numerical analysis using the finite element program PLAXIS 2D. The partially saturated collapsible soil is stimulated using the Mohr</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">Coulomb soil model. The significance parameters are considered two types of footing systems, collapsible soil thickness, use of sand cushion with geo-grid reinforcement at the bottom third of its thickness, and different clear spacing between source of surface water and strip footings on the stress-settlement relationship. The results of this study confirmed that the most important soil parameters in this problem are the use of reinforced sand cushion, decrease applied stress as well as rigid inverted T-section strip footing are more suitable for controlling Soil collapsibility, while the settlement is found to decrease. To avoid </span><span style="font-family:Verdana;">many</span><span style="font-family:Verdana;"> observation of spread footing disaster that founded and rest on collapse soil. In addition, the results can be guide for design engineers, how to choose foundation type and the effect of spacing water resource.展开更多
A new method for analysis of counter beams is presented in the paper. The analysis has taken into account their stiffness EI, Winkler’s space with modulus of subgrade reaction k and equality deformities of the founda...A new method for analysis of counter beams is presented in the paper. The analysis has taken into account their stiffness EI, Winkler’s space with modulus of subgrade reaction k and equality deformities of the foundation beam with the ground. The solution is found by using the numerical analysis of the Winkler’s model, with variation of different moduli of the subgrade reaction k2 outside the force zone r, while under the force P exists the modulus of the subgrade reaction k, up to the definition of minimum bending moments. The exponential function k2(r), as the geometric position of the minimum moments is approximately assumed. From the potential energy conditions of the reciprocity of displacement and reaction, the width of the zone r and the modulus of the subgrade reaction k2 are explicitly determined, introducing in the calculation initial and calculation soil displacement wsi successively. At the end of the paper, it presented numerical example in which the influence of k and k2 values on bending moments of the counter beam is analyzed. The essential idea of this paper is to decrease the quantity of the reinforcement in the foundations, beams, i.e. to obtain a cost-efficient foundation construction.展开更多
为解决传统数字滤波器在有限精度实现时因有限字长(Finite Word Length,FWL)效应导致滤波器性能下降的问题,提出一种L_(2)灵敏度最小化的数字滤波器状态空间实现稀疏化方法.推导前向差分算子数字滤波器结构传输函数及其等效状态空间实现...为解决传统数字滤波器在有限精度实现时因有限字长(Finite Word Length,FWL)效应导致滤波器性能下降的问题,提出一种L_(2)灵敏度最小化的数字滤波器状态空间实现稀疏化方法.推导前向差分算子数字滤波器结构传输函数及其等效状态空间实现,根据可控及可观格莱姆矩阵得到基于相似变换矩阵的L_(2)灵敏度表达式,并进行稀疏化校准,将L_(2)灵敏度最小化问题转换为凸函数求最值问题,求导得到L_(2)灵敏度最小化表达式,代回即得前向差分算子数字滤波器的稀疏化状态空间实现.仿真结果表明,所提方法设计的数字滤波器具有更好的抗FWL效应.展开更多
文摘This study aims at investigating the effect of using L 1 （Arabic Language） while teaching a target language （English Language） on the achievement in General English of foundation year students in King Abdulaziz University. To achieve the purpose of the study, the researcher used an experimental design： an experimental group and a control group. The independent variable is using L1 while teaching English in very limited and specified areas. The dependent variable is students＇ achievement in general English. The statistics used is the t-test. The population of the study was all students enrolled in the foundation year 1431/1432 in the ELI （English Language Institute） at King Abdulaziz University. The sample of the study consisted of 50 students taking North Star in the sections A and B as a university requirement in the foundation year 1431/1432 in King Abdulaziz University. The results of the study were in favor of banning Arabic in the English language classroom as shown in the mean scores of the control and experimental groups in the tables. It is recommended that teachers and instructors should be trained to use teaching strategies that help them use English only in the English language classroom.
基金the National Natural Science Foundation of China (Nos. 41202215 and 40972192)the Innovation Program of Shanghai Municipal Education Commission (No. 11ZZ88)the Innovation Foundation of Shanghai University
文摘A two-dimensionM discrete element code, particle flow code （PFC2D）, is employed to investigate foundations reinforced with horizontal-vertical （H-V） inclusions. The initial states and loading processes of both unreinforced and H-V reinforced foundations are simulated by PFC2D method. The interface between particles and reinforcements, and the reinforcement mechanism of the H-V reinforced foundations are studied through stress distribution graphs, displacement vector graphs and contact force graphs. The simulation results demonstrate that the vertical elements of the H-V reinforcement keep the particles from being displaced under the applied load. The H-V reinforcement can distribute the load uniformly over a wider area, thereby improving the bearing capacity of soil foundation.
文摘Since collapsible soils are been mostly transported by wind and deposited in arid or semi-arid regions, they founded in a state of unsaturated condition. In addition, engineering filling when placed in a certain none want density, undesired settlement will be predictable either due to wetting or due to loading on these soil deposits. Collapsibility study is important for the foundation design and construction on these soils. The most foundation systems used on these soils are isolated and strip footing connected with concrete tie beams. Therefore studying rigid foundation system resting on partially saturated collapsible soil/deposits is very imp</span><span style="font-family:Verdana;">o</span><span style="font-family:Verdana;">rtant. The present work investigated using rigid strip footing resting in collapsible soils to study the effect of stress interference due to progressive wetting depth from leakage of surface water on collapsibility settlement. The study has been investigated the influence of different behavior of strip footing and inverted T-section strip footing rigidity system resting on unsaturated soil by numerical analysis using the finite element program PLAXIS 2D. The partially saturated collapsible soil is stimulated using the Mohr</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">Coulomb soil model. The significance parameters are considered two types of footing systems, collapsible soil thickness, use of sand cushion with geo-grid reinforcement at the bottom third of its thickness, and different clear spacing between source of surface water and strip footings on the stress-settlement relationship. The results of this study confirmed that the most important soil parameters in this problem are the use of reinforced sand cushion, decrease applied stress as well as rigid inverted T-section strip footing are more suitable for controlling Soil collapsibility, while the settlement is found to decrease. To avoid </span><span style="font-family:Verdana;">many</span><span style="font-family:Verdana;"> observation of spread footing disaster that founded and rest on collapse soil. In addition, the results can be guide for design engineers, how to choose foundation type and the effect of spacing water resource.
文摘A new method for analysis of counter beams is presented in the paper. The analysis has taken into account their stiffness EI, Winkler’s space with modulus of subgrade reaction k and equality deformities of the foundation beam with the ground. The solution is found by using the numerical analysis of the Winkler’s model, with variation of different moduli of the subgrade reaction k2 outside the force zone r, while under the force P exists the modulus of the subgrade reaction k, up to the definition of minimum bending moments. The exponential function k2(r), as the geometric position of the minimum moments is approximately assumed. From the potential energy conditions of the reciprocity of displacement and reaction, the width of the zone r and the modulus of the subgrade reaction k2 are explicitly determined, introducing in the calculation initial and calculation soil displacement wsi successively. At the end of the paper, it presented numerical example in which the influence of k and k2 values on bending moments of the counter beam is analyzed. The essential idea of this paper is to decrease the quantity of the reinforcement in the foundations, beams, i.e. to obtain a cost-efficient foundation construction.
文摘为解决传统数字滤波器在有限精度实现时因有限字长(Finite Word Length,FWL)效应导致滤波器性能下降的问题,提出一种L_(2)灵敏度最小化的数字滤波器状态空间实现稀疏化方法.推导前向差分算子数字滤波器结构传输函数及其等效状态空间实现,根据可控及可观格莱姆矩阵得到基于相似变换矩阵的L_(2)灵敏度表达式,并进行稀疏化校准,将L_(2)灵敏度最小化问题转换为凸函数求最值问题,求导得到L_(2)灵敏度最小化表达式,代回即得前向差分算子数字滤波器的稀疏化状态空间实现.仿真结果表明,所提方法设计的数字滤波器具有更好的抗FWL效应.
