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排序方式: 共有143条查询结果,搜索用时 15 毫秒
1.
对理想(主理想)的和、交与积等性质做进一步的推广,给出了任意多个理想(主理想)的和、交与积的性质.  相似文献   
2.
为解决自动导引小车(Automated Guided Vehicle,AGV)与轨道式龙门起重机(Rail-Mounted Gantry Crane,RMG)的协同调度问题,考虑AGV和RMG的任务分配约束,以卸船作业最小完工时间为目标,建立混合整数规划(Mixed Integer Programming,MIP)模型.改变AGV,岸桥和箱区数量的配置,得出不同条件下的完工时间.对该问题设计两组算例:小规模算例采用CPLEX软件和遗传算法(Genetic Algorithm,GA)分别进行求解,通过结果对比验证GA的有效性;大规模算例采用GA求解,给出自动化码头设备调度优化方案.分析结果表明,卸船完工时间随着卸船任务量的增加而增加,随着AGV,岸桥和箱区数量的增加而减少,且AGV和岸桥数量的增加对完工时间的影响大于箱区数量的增加时完工数量的影响.  相似文献   
3.
利用循环小数刻画了不定方程x2=(10k 1)y的正整数解x、y的结构,给出了平方数是连整数的一个充要条件,进而给出了所有是平方数的二重连整数(同时否定了文[1]的猜想)。  相似文献   
4.
珠三角城市群内部职能专业化水平测度与分析   总被引:1,自引:0,他引:1  
对珠三角城市群内部职能专业化水平进行测算,并与产业结构专业化和长三角地区职能专业化水平进行比较。结果显示,珠三角地区产业结构保持基本稳定,但职能专业化水平呈不断上升的趋势,特别是在实施珠江三角洲地区改革发展规划纲要和产业转移政策以来,职能专业化水平上升更为明显,并已高于长三角地区。但职能专业化水平与国际发达地区相比还存在一定差距。  相似文献   
5.
Ensuring quality of laboratory services is the need of the hour in the field of health care. Keeping in mind the revolution ushered by six sigma concept in corporate world, health care sector may reap the benefits of the same. Six sigma provides a general methodology to describe performance on sigma scale. We aimed to gauge our laboratory performance by sigma metrics. Internal quality control (QC) data was analyzed retrospectively over a period of 6 months from July 2009 to December 2009. Laboratory mean, standard deviation and coefficient of variation were calculated for all the parameters. Sigma was calculated for both the levels of internal QC. Satisfactory sigma values (>6) were elicited for creatinine, triglycerides, SGOT, CPK-Total and Amylase. Blood urea performed poorly on the sigma scale with sigma <3. The findings of our exercise emphasize the need for detailed evaluation and adoption of ameliorative measures in order to effectuate six sigma standards for all the analytical processes.  相似文献   
6.
理论分析了光束具有的自旋角动量传递给晶体并导致其旋转的机理。并以碳酸钙粒子为例从理论上的分析了有效功率,粒子形状和大小,以及粘滞系数对旋转角速度的影响。对实验中如何提高晶体旋转角速度具有一定参考价值。  相似文献   
7.
采用2001~2011年辽宁省农村居民人均消费支出数据,运用恩格尔系数法对其进行分析,揭示了现阶段辽宁省农村居民的消费特征.  相似文献   
8.
To cope with ambiguous and/or underspecified queries, search result diversification (SRD) is a key technique that has attracted a lot of attention. This paper focuses on implicit SRD, where the subtopics underlying a query are unknown. Many existing methods appeal to the greedy strategy for generating diversified results. A common practice is using a heuristic criterion for making the locally optimal choice at each round. As a result, it is difficult to know whether the failures are caused by the optimization criterion or the setting of parameters. Different from previous studies, we formulate implicit SRD as a process of selecting and ranking k exemplar documents through integer linear programming (ILP). The key idea is that: for a specific query, we expect to maximize the overall relevance of the k exemplar documents. Meanwhile, we wish to maximize the representativeness of the selected exemplar documents with respect to the non-selected documents. Intuitively, if the selected exemplar documents concisely represent the entire set of documents, the novelty and diversity will naturally arise. Moreover, we propose two approaches ILP4ID (Integer Linear Programming for Implicit SRD) and AP4ID (Affinity Propagation for Implicit SRD) for solving the proposed formulation of implicit SRD. In particular, ILP4ID appeals to the strategy of bound-and-branch and is able to obtain the optimal solution. AP4ID being an approximate method transforms the target problem as a maximum-a-posteriori inference problem, and the message passing algorithm is adopted to find the solution. Furthermore, we investigate the differences and connections between the proposed models and prior models by casting them as different variants of the cluster-based paradigm for implicit SRD. To validate the effectiveness and efficiency of the proposed approaches, we conduct a series of experiments on four benchmark TREC diversity collections. The experimental results demonstrate that: (1) The proposed methods, especially ILP4ID, can achieve substantially improved performance over the state-of-the-art unsupervised methods for implicit SRD. (2) The initial runs, the number of input documents, query types, the ways of computing document similarity, the pre-defined cluster number and the optimization algorithm significantly affect the performance of diversification models. Careful examinations of these factors are highly recommended in the development of implicit SRD methods. Based on the in-depth study of different types of methods for implicit SRD, we provide additional insight into the cluster-based paradigm for implicit SRD. In particular, how the methods relying on greedy strategies impact the performance of implicit SRD, and how a particular diversification model should be fine-tuned.  相似文献   
9.
The standard deviation is related to the mean by virtue of the coefficient of variation. Teachers of statistics courses can make use of that fact to make the standard deviation more comprehensible for statistics students.  相似文献   
10.
在J.K.Langley给出的高阶齐次线性微分方程复振荡的结果的基础上,考虑具有控制系数和系数仅有有限个极点的高阶线性齐次微分方程,研究亚纯系数齐次线性微分方程亚纯解的零点收敛指数,得到了这类方程的线性无关超越解的最少个数和零点收敛指数为有穷的解的最多个数。  相似文献   
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