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排序方式: 共有267条查询结果,搜索用时 15 毫秒
1.
设计认知无线网络路由算法时,需要兼顾主用户保护与路由性能两个方面。为了提高认知无线网络中次用户之间路由的端到端性能,提出了基于无线电环境地图的路由优化机制,该机制中无线电环境地图能够为次用户提供主用户保护有关的无线电环境数据。首先,无线电环境地图根据次用户的数据请求将各授权频段的可用概率与功率控制相关信息反馈到该次用户;其次,次用户可以计算出与上一跳次用户之间的链路稳定性以及传输时延;最后,目的次用户通过计算每条路由的端到端吞吐量的期望值,然后选取期望值最大的一条路由。仿真结果表明,该路由机制在平均分组投递率、平均端到端吞吐量、平均端到端时延方面均优于对比路由算法。  相似文献   
2.
王晓青  吴秋明  周霖 《技术经济》2020,39(8):104-113
以Web of Science核心合集中收录的1990-2019年710篇企业孵化器相关文献为研究对象,基于CiteSpace可视化分析工具,绘制知识图谱。通过文献的时空分布,文献共被引分析,关键词共现网络分析等了解企业孵化器国际研究的概况、知识基础和研究热点。结果显示,企业孵化器国际研究发文量在近3年出现爆发式增长;知识基础大致可以分为两类:企业孵化器的作用和发展研究,对企业孵化器绩效的评估。研究热点主要集中在四个方面:企业孵化器绩效评价,企业孵化器绩效的影响因素分析,孵化网络与资源流动,孵化器对中小企业成长的影响。并提出对企业孵化器研究的未来展望。  相似文献   
3.
高速移动环境下,无线信道具有时频双选性衰落的特性,使得滤波器组多载波(Filter Bank Multi-carrier,FBMC)系统产生长突发差错。将一种基于Baker映射的混沌交织算法应用在滤波器组多载波系统中,根据混沌密钥对发送数据进行分块和重新排列,按照Baker映射规则完成数据交织。此方法可以将长突发差错变为单突发差错,结合卷积编码能有效地纠正双选信道产生的长突发差错。仿真结果表明,在双选择信道中,基于混沌交织的滤波器组多载波系统误比特率性能优于传统基于块交织的滤波器组多载波系统。  相似文献   
4.
A lack of empirical studies on Supply Chain Risk Management (SCRM) is observed, especially in the industries of large projects. Therefore, this paper conducts a risk analysis on the Brazilian Shipbuilding Industry by generating an initial risk profile. A panel was conducted with executives from major shipyards, and the primary risks were identified, assessed, and evaluated. Findings corroborate the academic literature, reinforcing that companies recognise the importance of SCRM, but the concept is incipient and far from being successfully implemented in real life. Despite the fact that the shipyards identified important risks, the focus was on internal factors. Because the industry was exposed to risks from the external environment, no risk mitigation actions existed, resulting in the bankruptcy of many shipbuilders. This research is an initial step toward investigating SCRM techniques, offering academics a novel empirical approach that can serve as a systematic risk management tool for supply chain planning.  相似文献   
5.
针对复杂电磁环境下卫星移动通信系统可靠通信需求,利用频谱地图多维数据呈现优势,提出了基于多维频谱地图的干扰规避方法。通过建立卫星移动通信系统波束、时隙、子频带、干扰强度等多维信息关联的频谱地图,利用数据挖掘方法对频谱可用情况进行预测,基于预测结果及用户QoS(Quality of Service)需求生成干扰规避策略,通过星地联合频谱资源调配实现系统干扰规避。该方法为卫星移动通信系统干扰规避提供了一种全新的思路,可提升卫星移动通信系统干扰防护能力。  相似文献   
6.
Carbon emission reduction could be achieved through extensive cooperation between relevant groups such as businesses, governments and consumers. Generally, carbon emissions stem from consumer behaviour. To tackle the increasingly serious energy crisis and climate change in China, it is thus vital to control carbon emissions generated by the country's urban consumers. From a consumption perspective, we utilize a self-organizing feature map model to analyse the spatial differentiation of per capita embedded carbon footprint (ECF) in urban China. We found that the spatial differentiation is significant with the per capita ECF of the east coastal area at a high level and that per capita disposable income is the key factor affecting ECF. Based on these findings, potential business opportunities to develop low-carbon products are discussed.  相似文献   
7.
This article explores how mental mapping can be used as a critical methodology for feminist migration studies. In a case study of female marriage migrants who settle in rural areas in South Korea from other Asian countries, I attempt to develop mental mapping to supplement verbal interviews. Mental maps of hometowns and current neighborhoods drawn by my interviewees represent their geographical imaginations and complex identity negotiations that mirror the change in their social locations. In order to understand multilayered meanings embedded in the images and the way in which power relations existent between the researcher and the researched affect the map production, I suggest a critical reading of the maps. The article shows how a reflexive and intertextual reading makes a difference to the interpretation of the maps. It argues that the maps are not mere reflections of the women's cognition, but rather socially constructed texts through which their desires, emotions, feelings and internal contradictions are expressed and negotiated. My research suggests that mental mapping, if ethically performed and critically evaluated, has potential as a means to convey the unheard voices of the marginalized to diverse audiences.  相似文献   
8.
We show that the set of competitive equilibrium points of a pure exchange economy are the equilibrium points of a broader class of better-response demands than the usual utility-maximizing demand functions. The better-response demands are derived from assigning weights to all commodity bundles with higher utility than the current commodity bundle, with the greatest weights being placed on the commodity bundles with the highest utility gain. The usual utility-maximizing demand functions are then those in which the weight on the utility-maximizing bundle is one. We also show that these better-response demands belong to a large class of response maps that are generated by monotonic transformations of the utility functions and/or monotonic transformations of the weights assigned to the commodity bundles.  相似文献   
9.
基于现有创新理论并结合当代技术发展特征,创建了多维技术创新地图,构建了基于多维技术创新地图维法耦合的技术创新路径。结合煤层气开采卸压消突创新实例,验证了该方法的可行性和有效性,即提高了技术创新路径构建的客观性,从技术创新本质层面指导技术创新活动的开展,有助于为企业开展技术创新活动提供决策支持。  相似文献   
10.
李云龙  刘铁良 《价值工程》2011,30(16):273-274
本文分析了常规的等值线绘制算法的缺点,根据经验提出了一种由离散数据生成等值线的算法,不但简单有效,又能达到更好的精度,而且适应能力更强,并且能方便地实现颜色填充,丰富了等值线图的表达能力。文中给出了具体算法的实现原理和过程。  相似文献   
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