全文获取类型
收费全文 | 223篇 |
免费 | 94篇 |
国内免费 | 24篇 |
出版年
2024年 | 2篇 |
2023年 | 1篇 |
2022年 | 6篇 |
2020年 | 13篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 9篇 |
2016年 | 12篇 |
2015年 | 13篇 |
2014年 | 19篇 |
2013年 | 23篇 |
2012年 | 25篇 |
2011年 | 19篇 |
2010年 | 11篇 |
2009年 | 18篇 |
2008年 | 13篇 |
2007年 | 23篇 |
2006年 | 17篇 |
2005年 | 17篇 |
2004年 | 24篇 |
2003年 | 12篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有341条查询结果,搜索用时 2 毫秒
331.
332.
333.
Accelerated life testing (ALT) is widely used to determine the failure time distribution of a product and the associated life‐stress relationship in order to predict the product's reliability under normal operating conditions. Many types of stress loadings such as constant‐stress, step‐stress and cyclic‐stress can be utilized when conducting ALT. Extensive research has been conducted on the analysis of ALT data obtained under a specified stress loading. However, the equivalency of ALT experiments involving different stress loadings has not been investigated. In this article, a log‐location‐scale distribution under Type I censoring is considered in planning ALT. An idea is provided for the equivalency of various ALT plans involving different stress loadings. Based on this idea, general equivalent ALT plans and some special types of equivalent ALT plans are explored. For demonstration, a constant‐stress ALT and a ramp‐stress ALT for miniature lamps are presented and their equivalency is investigated. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010 相似文献
334.
从概率论和信息论两个角度对单一基窃听方式下B92协议的安全性进行了研究,得出了最佳窃听角度和信源概率分布之间的关系;以马尔柯夫串联信道模型计算了Alice和Eve之间及Alice和Bob之间的信息量,并与广义量子测量窃听进行了比较,结果表明,Eve采用单一基窃听不仅能以较高概率猜中Alice发出的量子态,并且能获得较高平均互信息.得出的结论为合法通信者的安全通信和对窃听者的检测提供了标准. 相似文献
335.
This article develops a mathematical model and heuristic algorithm to design recreational boating mooring fields. The boating industry is important to the Florida economy, and boat storage is becoming a concern among those in the industry. The mooring field design problem is formulated to maximize the total number of boat feet moored in the mooring field. In the model, we allow two adjacent moorings to overlap, which introduces a risk that under certain conditions the boats on these moorings could contact each other. We identify the conditions when contact is possible and quantify the probability of contact. The mooring field design problem is formulated as a nonlinear mixed‐integer programming problem. To solve the problem, we decompose it into two separate models, a mooring radii assignment model and a mooring layout model, which are solved sequentially. The first is solved via exhaustive enumeration and the second via a depth‐first search algorithm. Two actual mooring fields are evaluated, and in both cases our model leads to better layouts than ones experts developed manually. The mooring field design model rationalizes the mooring field design and shows that in one case by increasing the risk from 0 to 1%, the mooring efficiency increases from 74.8% to 96.2%. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009 相似文献
336.
We present a computationally efficient procedure to determine control policies for an infinite horizon Markov Decision process with restricted observations. The optimal policy for the system with restricted observations is a function of the observation process and not the unobservable states of the system. Thus, the policy is stationary with respect to the partitioned state space. The algorithm we propose addresses the undiscounted average cost case. The algorithm combines a local search with a modified version of Howard's (Dynamic programming and Markov processes, MIT Press, Cambridge, MA, 1960) policy iteration method. We demonstrate empirically that the algorithm finds the optimal deterministic policy for over 96% of the problem instances generated. For large scale problem instances, we demonstrate that the average cost associated with the local optimal policy is lower than the average cost associated with an integer rounded policy produced by the algorithm of Serin and Kulkarni Math Methods Oper Res 61 (2005) 311–328. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2009 相似文献
337.
射击策略的选择在随机格斗中是一重要战术问题,当一方武器面临多个武器目标时,如何确定射击目标顺序的研究,显然是具有实际意义的。依据发射间隔服从负指数分布的多对一随机格斗中最优策略应满足的条件,推出求解此类多对一格斗最优策略的方法。进而研究了射击间隔服从此类分布的多对二随机格斗中处于劣势一方的射击策略选择问题,得出寻求最优射击策略的一般方法。 相似文献
338.
339.
矩阵开关技术在通用ATS电源模块自检中的应用 总被引:2,自引:0,他引:2
针对通用ATS中电源模块检查过程中存在检查时间长、劳动量大、工作效率低且易出错等问题,将矩阵开关技术引入通用ATS中电源模块的自检过程中,选取电压信号的均值和均方差作为评价电源模块性能的特征参数,并利用矩阵开关的多路复用功能设计了电源模块自检的拓扑结构,实现了自检过程中多通道的自动配置。仿真验证试验说明了该方法具有多通道自动配置、自检时间短、故障定位准确等优点。 相似文献
340.
针对圆(近圆)轨道航天器相对运动的固定时间状态转移问题,提出了一种基于导航点的多脉冲优化轨迹生成策略.从相对运动动力学出发,应用最优控制理论给出了基于连续推力的最优转移轨线,将引入的导航点限定在最优转移轨线上得到其位置参数;然后利用导航点位置参数建立了脉冲约束下的基于脉冲的优化轨迹生成模型,采用二次规划算法求解,通过改变导航点位置和脉冲间隔优化轨迹.仿真算例验证了策略的有效性. 相似文献