Objective To estimate the relative effect of early vs. late tracheotomy on clinical end-points in unselected intensive care unit （ICU） patients undergoing mechanical ventilation. Methods We searched electronic data...Objective To estimate the relative effect of early vs. late tracheotomy on clinical end-points in unselected intensive care unit （ICU） patients undergoing mechanical ventilation. Methods We searched electronic databases （up to February 27, 2013） for both randomized control trials and observational studies satisfying the predefined inclusion criteria.展开更多
This paper considers the parallel machines scheduling problem where jobs are subject to different release times. A constructive heuristic is first proposed to solve the problem in a modest amount of computer time. In ...This paper considers the parallel machines scheduling problem where jobs are subject to different release times. A constructive heuristic is first proposed to solve the problem in a modest amount of computer time. In general, the quality of the solutions provided by heuristics degrades with the increase of the probiem’s scale. Combined the global search ability of genetic algorithm, this paper proposed a hybrid heuristic to improve the quality of solutions further. The computational results show that the hybrid heuristic combines the advantages of heuristic and genetic algorithm effectively and can provide very good solutions to some large problems in a reasonable amount of computer time.展开更多
文摘逆时偏移成像建立在全波波动方程基础上,偏移成像结果精准,但偏移时计算耗时长,影响了逆时偏移的实际应用.以缩短逆时偏移的计算时间为目的,分析造成计算耗时的原因,采用基于提升构架的整数小波变换的多级树集合分裂(set partitioning in hierarchical tree,SPIH了)图像编码方法降低逆时偏移计算时的内存占有量,解决了计算耗时过长的问题,提高了综合计算效率.对Marmousi模型叠前深度逆时偏移处理表明,该方法能较好地解决逆时偏移计算耗时的问题,而且不影响成像精度.
文摘Objective To estimate the relative effect of early vs. late tracheotomy on clinical end-points in unselected intensive care unit （ICU） patients undergoing mechanical ventilation. Methods We searched electronic databases （up to February 27, 2013） for both randomized control trials and observational studies satisfying the predefined inclusion criteria.
文摘This paper considers the parallel machines scheduling problem where jobs are subject to different release times. A constructive heuristic is first proposed to solve the problem in a modest amount of computer time. In general, the quality of the solutions provided by heuristics degrades with the increase of the probiem’s scale. Combined the global search ability of genetic algorithm, this paper proposed a hybrid heuristic to improve the quality of solutions further. The computational results show that the hybrid heuristic combines the advantages of heuristic and genetic algorithm effectively and can provide very good solutions to some large problems in a reasonable amount of computer time.
