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1.
组网是卫星、无人机等飞行器集群实现协同的基础。传统自组织组网技术针对地面随机移动场景设计,不适用于拓扑和传输根据任务变化的飞行器集群场景,为此设计了一种管理与任务分离的组网方法,将网络分为管理面和任务面两个逻辑层面,管理面负责拓扑发现、路由建立、任务规划等基础组网功能,任务面负责任务执行过程中的数据传输功能。管理面和任务面实行不同的组网策略,从而使得网络的传输性能根据管理和任务执行的不同需求进行优化,以减少协议开销及降低传输自干扰。  相似文献   
2.
中国经济已经到了只有转型升级才能持续健康发展的关键阶段,产业转型升级在国家政策文件和研究文献中出现的词频较高。文章以我国物流业为研究对象,从现有涉及到物流业转型升级方面的文献挖掘有效信息,梳理我国物流业转型升级研究的历史脉络,从供应链与价值链、产业集群、现代科学技术应用和产业联动四个视角对现有的物流业转型升级文献进行了总结和归纳,并从物流业转型升级的动力研究、阶段性划分研究和演进规律研究三个方面指出了现有文献的研究不足和以后可能的研究方向。其中,供应链与价值链视角侧重于物流企业的纵向角度,产业集群视角侧重于物流企业的横向角度。文章对于物流企业战略设计、政府政策的制定和理论研究具有一定的参考作用。  相似文献   
3.
基于聚类分析电信运营企业仓库布局优化研究   总被引:1,自引:0,他引:1  
祝丽  汝宜红  罗平 《物流技术》2007,26(8):106-109
以某电信运营企业为例,在现场调研的基础上,分析了企业仓库布局的主要问题,应用聚类分析方法,提出了仓库布局优化方案,并进行了方案的综合评价.  相似文献   
4.
本文运用灰色系统理论中的灰色聚类数学模型,对四个金矿床勘探类型进行了划分,取得了比较满意的效果。  相似文献   
5.
产业集群的蓬勃发展带动了我国区域经济迅速发展,但当前我国产业集群中企业创新不足的问题日益显现,阻碍了产业集群的进一步发展,而要强化产业集群技术创新,关键是探寻技术创新的实现路径,整合创新要素,做出有利于推进产业集群技术创新的战略选择.  相似文献   
6.
Robustness issues in multilevel regression analysis   总被引:8,自引:0,他引:8  
A multilevel problem concerns a population with a hierarchical structure. A sample from such a population can be described as a multistage sample. First, a sample of higher level units is drawn (e.g. schools or organizations), and next a sample of the sub‐units from the available units (e.g. pupils in schools or employees in organizations). In such samples, the individual observations are in general not completely independent. Multilevel analysis software accounts for this dependence and in recent years these programs have been widely accepted. Two problems that occur in the practice of multilevel modeling will be discussed. The first problem is the choice of the sample sizes at the different levels. What are sufficient sample sizes for accurate estimation? The second problem is the normality assumption of the level‐2 error distribution. When one wants to conduct tests of significance, the errors need to be normally distributed. What happens when this is not the case? In this paper, simulation studies are used to answer both questions. With respect to the first question, the results show that a small sample size at level two (meaning a sample of 50 or less) leads to biased estimates of the second‐level standard errors. The answer to the second question is that only the standard errors for the random effects at the second level are highly inaccurate if the distributional assumptions concerning the level‐2 errors are not fulfilled. Robust standard errors turn out to be more reliable than the asymptotic standard errors based on maximum likelihood.  相似文献   
7.
Chi-Yo  Joseph Z.  Gwo-Hshiung   《Technovation》2007,27(12):744-765
Since the year 2000, silicon intellectual property (SIP), which can minimize the gap in ‘design productivity’ that exists with systems-on-chip (SOC), has become one of the most important factors in the development of integrated circuit (IC) products in the SOC era. Although SIP is very important for IC industry development, complicated business, technical as well as legal issues inside SIP transactions have hindered successful transactions and the integration of SIPs into SOCs. Thus, web-based SIP e-Commerce mechanisms, called SIP Malls, have emerged, aiming to resolve complex SIP issues. To maintain its leading position and competitiveness in the World's IC industry, as well as the value added by SOC products in Taiwanese IC firms, the Taiwanese government has developed SIP Malls, using innovation policy tools. However, the Taiwanese SIP Mall industry remains immature. No existing Taiwanese SIP Malls generate a profit or account for a significant share of worldwide SIP transactions. This research will develop an analytical framework for defining an innovation policy portfolio that aims to develop Taiwan's SIP Mall industry, so that it will enhance the value added of SIP Malls and, thus, the nation's competitiveness in the SIP and IC industries, something which already has become one of the Taiwanese government's major concerns. The industry innovation requirements (IIRs) are summarized using the Delphi method. Meanwhile, the major IIRs identified by Decision Making Trial and Evaluation Laboratory (DEMATEL) are introduced. After the IIRs are derived, the relationships between the IIRs and innovation policy tools are derived by Grey relational analysis (GRA). Then, the innovation policy tools are clustered, based upon the Grey grades derived by GRA. Finally, reconfigured innovation policy portfolios are presented for the Taiwanese government's policy definition. The results demonstrate that developing an innovative policy portfolio that includes scientific, technical, educational, public enterprise, information, legal and regulatory, financial, and taxation policy tools will be the most necessary step towards developing Taiwan's SIP Mall industry.  相似文献   
8.
灰色聚类综合评价方法在住宅建筑方案选优中的应用   总被引:2,自引:2,他引:2  
阐述了基于灰色聚类原理开发出的一种综合评价方法,其应用于住宅建筑方案选优,既可选出相对最优方案,又可直观地评出其属于何种等级的灰类。  相似文献   
9.
The underlying “architecture of the decision to pursue a degree in psychology was quantified using the Method of Sorting technique to identifying the critical issues necessary to make this choice. Multidimentsional scaling procedures were employed to construct a three-dimensional map representing the relationships between reasons for selecting psychology as a major. Freshman and senior psychology majors (N = 165) from a regional university and a large research-based institution rated the relative importance of items in their decision-making process. Hierarchical clustering procedures revealed seven different groups of students. Although significant differences associated with class standing were not found, institutional affiliation did influence cluster composition. Reflecting local emphases, students at the regional institution had a greater interest in Counseling Psychology, whereas those at the research-based school focused on Clinical Psychology. This semantic map and the associated item clusters arising from psychology student data provides an empirical basis for, amongst other things, course selection, faculty-initiated program design or revision, strategic niche marketing, and student retention.  相似文献   
10.
基于模糊综合评判的物流运输企业客户群体价值评估   总被引:1,自引:0,他引:1  
徐丽娟 《物流技术》2007,26(4):40-42
论述了物流运输企业实施客户群体价值评估的意义,给出了基于模糊综合评判的对现代物流运输企业客户进行价值评价的基本思路。  相似文献   
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