The goal of computational science is to develop models that predict phenomena observed in nature. However, these models are often based on parameters that are uncertain. In recent decades, main numerical methods for s...The goal of computational science is to develop models that predict phenomena observed in nature. However, these models are often based on parameters that are uncertain. In recent decades, main numerical methods for solving SPDEs have been used such as, finite difference and finite element schemes [1]-[5]. Also, some practical techniques like the method of lines for boundary value problems have been applied to the linear stochastic partial differential equations, and the outcomes of these approaches have been experimented numerically [7]. In [8]-[10], the author discussed mean square convergent finite difference method for solving some random partial differential equations. Random numerical techniques for both ordinary and partial random differential equations are treated in [4] [10]. As regards applications using explicit analytic solutions or numerical methods, a few results may be found in [5] [6] [11]. This article focuses on solving random heat equation by using Crank-Nicol- son technique under mean square sense and it is organized as follows. In Section 2, the mean square calculus preliminaries that will be required throughout the paper are presented. In Section 3, the Crank-Nicolson scheme for solving the random heat equation is presented. In Section 4, some case studies are showed. Short conclusions are cleared in the end section.展开更多
The physical aging behavior of atactic polystyrene (aPS) films achieved under different drawing conditions has been studied by optical birefringence and modulate differential scanning: calorimeter (m.d.s.c.). The resu...The physical aging behavior of atactic polystyrene (aPS) films achieved under different drawing conditions has been studied by optical birefringence and modulate differential scanning: calorimeter (m.d.s.c.). The results show that on annealing at specific temperature below glass transition temperatue (T-g), the enthalpy relaxation (Delta H) and T-g decrease with increasing of birefringence (Delta n). On the other baud, the effect of molecular draw ratio (MDR) is confusing: Delta H and T-g decrease with increasing of MDR in the early stage of aging, but the MDR's effect become unobvious with the development of aging. It may be concluded that the ordered domain generated by the drawing below or above glass transition temperature will affect the development of physical aging behavior. The viewpoint of cohesional entanglement is used to account for the above observations.展开更多
Land was important--in the course of spreading and seeking new converts--for both Missionaries of Africa （White Fathers） and Church Missionary Society （C.M.S.） in Buha, Western Tanzania. This paper examines the la...Land was important--in the course of spreading and seeking new converts--for both Missionaries of Africa （White Fathers） and Church Missionary Society （C.M.S.） in Buha, Western Tanzania. This paper examines the land question as one of the challenges that the White Fathers encountered in their attempt to evangelize communities in Western Tanzania. I argue that the land question remained throughout the late-colonial period one of the unresolved issues, and at some mission stations, impeded the activities of the White Fathers and C.M.S. missionaries. This paper relies on archival documents first, to examine the land question and White Fathers-C.M.S. relations in Buha from 1934 to 1959. Second, I intend to demonstrate the fact that land issues remained at the heart of the missionary enterprise in Buha. Both Catholic and Anglican missionaries were determined to have more mission plots for medical, education and religious purposes.展开更多
One of the contaminants in coal is sulphur. The adverse impact of sulfur on coal, such as environmental pollution, degradation of steel quality, and reduction of coal’s thermal value, has led to the attention of sulf...One of the contaminants in coal is sulphur. The adverse impact of sulfur on coal, such as environmental pollution, degradation of steel quality, and reduction of coal’s thermal value, has led to the attention of sulfur separation methods in recent decades. Leaching (chemical dissolution) is one of the best methods for desulfurising coal, reducing sulfur in coal. In this study, hydrogen peroxide as an oxidising agent on sulfuric acid yield in reducing sulfur types of coal and chemical structure and the organic texture of high sulfur coal was investigated. The experiments were designed using a three-level response surface methodology with four duplicate points and 27 experiments. The independent variables studied were temperature, time, stirring speed and ratio of sulfuric acid to hydrogen peroxide. Dependent variables included reduction percentage of total, pyritic and organic sulfur. This study showed that 99.99% of total sulfur, 30.11% of pyritic sulfur and 69.08% of organic sulfur were reduced. These values were obtained at a temperature of 60°C, time 120 min, stirring speed 200 rpm and 3:1 ratio of sulfuric acid to hydrogen peroxide. Significant changes were observed by infrared spectroscopy (FTIR) of the coal structure before and after desulphurisation. On the other hand, the studies showed no specific changes in the bonds related to the organic coal matrix. The results showed that this method could be used as a secure process for removing inorganic and organic sulfur without destroying the organic coal matrix.展开更多
An algorithm for solving the satisfiability problem is presented. It isproceed that this algorithm solves 2-SAT and Horn-SAT in linear time and k-positiveSAT (in which every clause contains at most k positive literals...An algorithm for solving the satisfiability problem is presented. It isproceed that this algorithm solves 2-SAT and Horn-SAT in linear time and k-positiveSAT (in which every clause contains at most k positive literals) ill time O(F.),where F is the length of input F, n is the number of atoms occurring in F, and k isthe greatest real number satisfying the equation x = 2-. Compared with previousresults, this nontrivial upper bound on time complexity could only be obtained fork-SAT, which is a subproblem of k-positive SAT.展开更多
文摘The goal of computational science is to develop models that predict phenomena observed in nature. However, these models are often based on parameters that are uncertain. In recent decades, main numerical methods for solving SPDEs have been used such as, finite difference and finite element schemes [1]-[5]. Also, some practical techniques like the method of lines for boundary value problems have been applied to the linear stochastic partial differential equations, and the outcomes of these approaches have been experimented numerically [7]. In [8]-[10], the author discussed mean square convergent finite difference method for solving some random partial differential equations. Random numerical techniques for both ordinary and partial random differential equations are treated in [4] [10]. As regards applications using explicit analytic solutions or numerical methods, a few results may be found in [5] [6] [11]. This article focuses on solving random heat equation by using Crank-Nicol- son technique under mean square sense and it is organized as follows. In Section 2, the mean square calculus preliminaries that will be required throughout the paper are presented. In Section 3, the Crank-Nicolson scheme for solving the random heat equation is presented. In Section 4, some case studies are showed. Short conclusions are cleared in the end section.
基金This work was Supported by the National Basic Research Project-Macromolecular Condensed State
文摘The physical aging behavior of atactic polystyrene (aPS) films achieved under different drawing conditions has been studied by optical birefringence and modulate differential scanning: calorimeter (m.d.s.c.). The results show that on annealing at specific temperature below glass transition temperatue (T-g), the enthalpy relaxation (Delta H) and T-g decrease with increasing of birefringence (Delta n). On the other baud, the effect of molecular draw ratio (MDR) is confusing: Delta H and T-g decrease with increasing of MDR in the early stage of aging, but the MDR's effect become unobvious with the development of aging. It may be concluded that the ordered domain generated by the drawing below or above glass transition temperature will affect the development of physical aging behavior. The viewpoint of cohesional entanglement is used to account for the above observations.
文摘Land was important--in the course of spreading and seeking new converts--for both Missionaries of Africa （White Fathers） and Church Missionary Society （C.M.S.） in Buha, Western Tanzania. This paper examines the land question as one of the challenges that the White Fathers encountered in their attempt to evangelize communities in Western Tanzania. I argue that the land question remained throughout the late-colonial period one of the unresolved issues, and at some mission stations, impeded the activities of the White Fathers and C.M.S. missionaries. This paper relies on archival documents first, to examine the land question and White Fathers-C.M.S. relations in Buha from 1934 to 1959. Second, I intend to demonstrate the fact that land issues remained at the heart of the missionary enterprise in Buha. Both Catholic and Anglican missionaries were determined to have more mission plots for medical, education and religious purposes.
文摘One of the contaminants in coal is sulphur. The adverse impact of sulfur on coal, such as environmental pollution, degradation of steel quality, and reduction of coal’s thermal value, has led to the attention of sulfur separation methods in recent decades. Leaching (chemical dissolution) is one of the best methods for desulfurising coal, reducing sulfur in coal. In this study, hydrogen peroxide as an oxidising agent on sulfuric acid yield in reducing sulfur types of coal and chemical structure and the organic texture of high sulfur coal was investigated. The experiments were designed using a three-level response surface methodology with four duplicate points and 27 experiments. The independent variables studied were temperature, time, stirring speed and ratio of sulfuric acid to hydrogen peroxide. Dependent variables included reduction percentage of total, pyritic and organic sulfur. This study showed that 99.99% of total sulfur, 30.11% of pyritic sulfur and 69.08% of organic sulfur were reduced. These values were obtained at a temperature of 60°C, time 120 min, stirring speed 200 rpm and 3:1 ratio of sulfuric acid to hydrogen peroxide. Significant changes were observed by infrared spectroscopy (FTIR) of the coal structure before and after desulphurisation. On the other hand, the studies showed no specific changes in the bonds related to the organic coal matrix. The results showed that this method could be used as a secure process for removing inorganic and organic sulfur without destroying the organic coal matrix.
文摘An algorithm for solving the satisfiability problem is presented. It isproceed that this algorithm solves 2-SAT and Horn-SAT in linear time and k-positiveSAT (in which every clause contains at most k positive literals) ill time O(F.),where F is the length of input F, n is the number of atoms occurring in F, and k isthe greatest real number satisfying the equation x = 2-. Compared with previousresults, this nontrivial upper bound on time complexity could only be obtained fork-SAT, which is a subproblem of k-positive SAT.
