This paper deals with the approximate solution of the Fredholm equation Lu= f of the second kind with f ∈H’(Γ). First, we give the order of the n-the optimal radius in the worst case setting. Then, we show that the...This paper deals with the approximate solution of the Fredholm equation Lu= f of the second kind with f ∈H’(Γ). First, we give the order of the n-the optimal radius in the worst case setting. Then, we show that the Galerkin method using 2n+1 inner products of f has minimal error. Finally, we give the estimate of the ε-complexity of the Fredholm problem of the second kind and Galerkin method in the worst case setting.展开更多
The order of computational complexity of all bounded linear functional ap proximation problem is determined for the generalized Sobolev class Wp?（Id）, Nikolskii class H|∞k（Id） in the worst （deterministic）, stoc...The order of computational complexity of all bounded linear functional ap proximation problem is determined for the generalized Sobolev class Wp?（Id）, Nikolskii class H|∞k（Id） in the worst （deterministic）, stochastic and average case setting, from which it is concluded that the bounded linear functional approximation problem for the classes Wp?（Id） and H∞k（Id） is intractable in worst case setting, but is tractable with respect to stochastic and average case setting.展开更多
Search-based software engineering has mainly dealt with automated test data generation by metaheuristic search techniques. Similarly, we try to generate the test data (i.e., problem instances) which show the worst cas...Search-based software engineering has mainly dealt with automated test data generation by metaheuristic search techniques. Similarly, we try to generate the test data (i.e., problem instances) which show the worst case of algorithms by such a technique. In this paper, in terms of non-functional testing, we re-define the worst case of some algorithms, respectively. By using genetic algorithms (GAs), we illustrate the strategies corresponding to each type of instances. We here adopt three problems for examples;the sorting problem, the 0/1 knapsack problem (0/1KP), and the travelling salesperson problem (TSP). In some algorithms solving these problems, we could find the worst-case instances successfully;the successfulness of the result is based on a statistical approach and comparison to the results by using the random testing. Our tried examples introduce informative guidelines to the use of genetic algorithms in generating the worst-case instance, which is defined in the aspect of algorithm performance.展开更多
To overcome disadvantages of traditional worst-case execution time （WCET） analysis approaches, we propose a new WCET analysis approach based on independent paths for ARM programs. Based on the results of program flo...To overcome disadvantages of traditional worst-case execution time （WCET） analysis approaches, we propose a new WCET analysis approach based on independent paths for ARM programs. Based on the results of program flow analysis, it reduces and partitions the control flow graph of the program and obtains a directed graph. Using linear combinations of independent paths of the directed graph, a set of feasible paths can be generated that gives complete coverage in terms of the program paths considered. Their timing measurements and execution counts of program segments are derived from a limited number of measurements of an instrumented version of the program. After the timing measurement of the feasible paths are linearly expressed by the execution times of program seg-ments, a system of equations is derived as a constraint problem, from which we can obtain the execution times of program segments. By assigning the execution times of program segments to weights of edges in the directed graph, the WCET estimate can be calculated on the basis of graph-theoretical techniques. Comparing our WCET estimate with the WCET measurement obtained by the exhaustive measurement, the maximum error ratio is only 8.259 3 %. It is shown that the proposed approach is an effective way to obtain the safe and tight WCET estimate for ARM programs.展开更多
[Objective] The paper aimed to analyze the meteorological factors of the worst drought in 2010 in Liupanshui City and its impact on the agriculture.[Method] To make research analyses based on the real-time meteorologi...[Objective] The paper aimed to analyze the meteorological factors of the worst drought in 2010 in Liupanshui City and its impact on the agriculture.[Method] To make research analyses based on the real-time meteorological data and the characters of this drought disaster.[Result]Due to the influence of abnormal atmospheric circulation and El Nio events,the convergence of warm and cold air in the arid are inadequate,so the rainfall reduced seriously,shortage of water resources,and successive drought disasters were intensified by hot and dry weather,moreover,special geographical environment(Karst,desertification,etc.)increased the danger of drought.[Conclusion] Local people faced the test of the severest drought in a century which had great impact on drinking water,agriculture,forestry,hydropower production,residents living and so on.Taking advantage of favorable meteorological conditions for artificial rainfall,and combined with scientific drought-relief measures could help to east the drought in advance and reduce the losses.展开更多
基金This work was partially supported by the Chinese National Science Fundation,the Chinese National High Technology Program(863).and the UNSW Vice-Chancellor's Post Doctoral Fellowship in Australia.
文摘This paper deals with the approximate solution of the Fredholm equation Lu= f of the second kind with f ∈H’(Γ). First, we give the order of the n-the optimal radius in the worst case setting. Then, we show that the Galerkin method using 2n+1 inner products of f has minimal error. Finally, we give the estimate of the ε-complexity of the Fredholm problem of the second kind and Galerkin method in the worst case setting.
基金Project supported by the Natural Science Foundation of China(10371009) and Research Fund for the Doctoral Program Higher Education.
文摘The order of computational complexity of all bounded linear functional ap proximation problem is determined for the generalized Sobolev class Wp?（Id）, Nikolskii class H|∞k（Id） in the worst （deterministic）, stochastic and average case setting, from which it is concluded that the bounded linear functional approximation problem for the classes Wp?（Id） and H∞k（Id） is intractable in worst case setting, but is tractable with respect to stochastic and average case setting.
文摘Search-based software engineering has mainly dealt with automated test data generation by metaheuristic search techniques. Similarly, we try to generate the test data (i.e., problem instances) which show the worst case of algorithms by such a technique. In this paper, in terms of non-functional testing, we re-define the worst case of some algorithms, respectively. By using genetic algorithms (GAs), we illustrate the strategies corresponding to each type of instances. We here adopt three problems for examples;the sorting problem, the 0/1 knapsack problem (0/1KP), and the travelling salesperson problem (TSP). In some algorithms solving these problems, we could find the worst-case instances successfully;the successfulness of the result is based on a statistical approach and comparison to the results by using the random testing. Our tried examples introduce informative guidelines to the use of genetic algorithms in generating the worst-case instance, which is defined in the aspect of algorithm performance.
基金Supported by the National High Technology Research and Development Program of China(863 Program,2009AA011705)the National Natural Science Foundation of China(60903033)
文摘To overcome disadvantages of traditional worst-case execution time （WCET） analysis approaches, we propose a new WCET analysis approach based on independent paths for ARM programs. Based on the results of program flow analysis, it reduces and partitions the control flow graph of the program and obtains a directed graph. Using linear combinations of independent paths of the directed graph, a set of feasible paths can be generated that gives complete coverage in terms of the program paths considered. Their timing measurements and execution counts of program segments are derived from a limited number of measurements of an instrumented version of the program. After the timing measurement of the feasible paths are linearly expressed by the execution times of program seg-ments, a system of equations is derived as a constraint problem, from which we can obtain the execution times of program segments. By assigning the execution times of program segments to weights of edges in the directed graph, the WCET estimate can be calculated on the basis of graph-theoretical techniques. Comparing our WCET estimate with the WCET measurement obtained by the exhaustive measurement, the maximum error ratio is only 8.259 3 %. It is shown that the proposed approach is an effective way to obtain the safe and tight WCET estimate for ARM programs.
文摘[Objective] The paper aimed to analyze the meteorological factors of the worst drought in 2010 in Liupanshui City and its impact on the agriculture.[Method] To make research analyses based on the real-time meteorological data and the characters of this drought disaster.[Result]Due to the influence of abnormal atmospheric circulation and El Nio events,the convergence of warm and cold air in the arid are inadequate,so the rainfall reduced seriously,shortage of water resources,and successive drought disasters were intensified by hot and dry weather,moreover,special geographical environment(Karst,desertification,etc.)increased the danger of drought.[Conclusion] Local people faced the test of the severest drought in a century which had great impact on drinking water,agriculture,forestry,hydropower production,residents living and so on.Taking advantage of favorable meteorological conditions for artificial rainfall,and combined with scientific drought-relief measures could help to east the drought in advance and reduce the losses.
