异构小蜂窝网络移动性管理研究综述

新一代移动通信网络不断演进为高密集、无定型、立体分层的异构网络,移动性管理旨在保证用户设备（user equipment,UE）移动通信服务的连续性和无缝切换及降低信令开销等。移动性管理问题正成为异构小蜂窝网络（heterogeneous and small cell networks,HetNets）中无线资源管理需要应对的关键性挑战之一。阐述了移动性管理的一般性问题,根据移动性管理的主要特征给出了一个综合分类：整体切换性能增强、小蜂窝发现与识别增强和无线链路失效（radio link failure,RLF）恢复增强。此外,依据此分类对近年来第三代合作伙伴计划（3rd genera-tion partnership project,3GPP）成员在无线接入网（radio access network,RAN）标准化工作组历次会议中提出的主要移动性管理增强方案进行了分类阐述和性能对比。对异构小蜂窝网络的移动性管理所面临的挑战和未来研究的趋势进行展望,并在此基础上进行了总结。     

手机铃声下载的著作权问题

手机铃声下载作为一种新型网络服务方式引发了一系列相关的著作权问题。通过对一起典型案例的分析,指出未经许可使用音乐作品作为手机铃声供人下载侵犯了作者的信息网络传播权,但是应当由网络内容提供商而非网络服务商承当由此产生的赔偿责任。此外,应当以合理方式确定著作权集体管理组织的相关收费标准,以促进作者利益与社会公共利益之间的平衡。     

Extinction risk assessment of declining wild populations: The case of the southern Bluefin Tuna

We estimate the extinction probability of a large and decreasing population, the southern bluefin tuna. This tuna was listed as critically endangered by the World Conservation Union (IUCN) in 1996. However, the absolute population size is still large and the extinction probability within the next half century is negligible if the recent population decline rate does not increase in the future. IUCN’s criterion with respect to the population decline rate should be linked to the absolute population size, if this is estimated. Several methods estimating the probability of extinction conclude that the southern bluefin tuna population will be below 500 mature individuals within the next 100 years and may be listed as vulnerable. These analyses suggest that extinction risk assessment is useful for management action for taxa that still have large population and are rapidly decreasing.     

基于随机权重多目标遗传算法的多目标动态单元构建方法

考虑多变的市场需求环境下单元生产系统在多个计划期具有多个目标的动态构建决策问题。通过对单元生产构建过程中的总费用、设备负载与能力之间最大偏差以及零部件跨单元移动的总次数3个目标进行权衡,建立了非线性多目标动态单元构建的数学模型。采用自适应小生境技术、惩罚技术、双轮盘赌法和精华选择策略,提出了基于精华保留策略的随机权重多目标遗传算法求解该组合优化问题。结合实例对模型和算法进行了仿真分析,结果显示了算法对解决多目标动态单元构建问题的有效性。     

An Alternative Exact Solution of the Two-Stage Clonal Growth Model of Cancer

The approximate solution of the two-stage clonal expansion model of cancer may substantially deviate from the exact solution, and may therefore lead to erroneous conclusions in particular applications. However, for time-varying parameters the exact solution (method of characteristics) is not easy to implement, hampering the accessibility of the model to nonmathematicians. Based on intuitive reasoning, Clewell et al. (1995) proposed an improved approximate solution that is easy to implement whatever time-varying behavior the parameters may have. Here we provide the mathematical foundation for the approximation suggested by Clewell et al. (1995) and show that, after a slight modification, it is in fact an exact solution for the case of time-constant parameters. We were not able to prove that it is an exact solution for time-varying parameters as well. However, several computer simulations showed that the numerical results do not differ from the exact solution as proposed by Moolgavkar and Luebeck (1990). The advantage of this alternative solution is that the hazard rate of the first malignant cell can be evaluated by numerically integrating a single differential equation.     

区域资源优势发挥与新农村建设协同发展探讨——以宁夏隆德县杨店民俗文化旅游村为例

杨店民俗文化旅游村在新农村建设中充分利用村庄地域优势和政府政策支持,不断推进新农村建设和发展,改善村庄的硬件服务设施,致力于提高村民的整体生活质量,并在村庄经济社会发展中,转变发展观念,更新发展思路,创新发展模式,依托丰富的红色旅游资源和绿色生态资源,与当地的民俗文化资源相结合,走出一条兴村富农的新路子。对当前我国新农村建设与发展模式的转变有一定的启示作用。     

四川省红色旅游共生图谱形成机理及演进态势研究——基于红色旅游与民族经济发展的视角

革命博物馆、纪念馆、党史馆、烈士陵园等是党和国家红色基因库,是具有鲜明政治导向、强大思想感召力和广泛教育意义的特色文化资源,籍此形成的红色旅游在我国的旅游发展格局以及当地经济社会发展中占据着重要地位。改革开放以来,我国取得的世界瞩目的发展成绩的客观事实、应对新冠疫情体现出的制度优势、实现中国梦愿景下攻坚克难的精神需求等共同催生了对红色旅游的发展期待。中国共产党选择的是农村包围城市的革命道路,红色旅游资源富集地也大多处于我国的老少边穷地区,红色旅游资源的开发利用和利益分享,关系到民族地区经济发展、社会安定和民生改善。本文以更好地发挥红色旅游在脱贫攻坚与乡村振兴衔接中的作用为旨向,运用共生理论,聚焦四川省这个特定区域,分析红色旅游共生体系的搭建历程、共生体系内各要素的内在关联、未来发展态势研判和应对举措等,以期为我国民族地区红色旅游高质量发展提供参考。     

红色旅游开发与区域旅游业新增长点的培育

培育区域旅游业新增长点是旅游业发展、革命老区脱贫致富、农村全面小康建设的需要。将红色旅游作 为区域旅游业新增长点来培育,具有资源比较优势、市场需求优势、政策扶持优势。发展红色旅游要发挥政府主导 作用、始终把社会效益放在首位、深入挖掘文化内涵、与革命老区和农村全面小康建设紧密结合、注意资源保护、促 进区城经济共同增长。     

光电池非线性区PN结光生伏特效应的研究

根据光电池线性区应用叠加定理建立的PN结光生伏特效应理论，阐述了PN结光生伏特效应在光电池非线性区的应用。     

Risk Assessment of Listeria monocytogenes: Impact of Individual Cell Variability on the Exposure Assessment Step

Recently, the lag phase research in predictive microbiology is focusing more on the individual cell variability, especially for pathogenic microorganisms that typically occur in very low contamination levels, like Listeria monocytogenes. In this study, the effect of this individual cell lag phase variability was introduced in an exposure assessment study for L. monocytogenes in a liver paté. A basic framework was designed to estimate the contamination level of paté at the time of consumption, taking into account the frequency of contamination and the initial contamination levels of paté at retail. Growth was calculated on paté units of 150 g, comparing an individual-based approach with a classical population-based approach. The two different protocols were compared using simulations. If only the individual cell lag variability was taken into account, important differences were observed in cell density at the time of consumption between the individual-based approach and the classical approach, especially at low inoculum levels, resulting in high variability when using the individual-based approach. Although, when all variable factors were taken into account, no significant differences were observed between the different approaches, allowing the conclusion that the individual cell lag phase variability was overruled by the global variability of the exposure assessment framework. Even in more extreme conditions like a low inoculum level or a low water activity, no differences were created in cell density at the time of consumption between the individual-based approach and the classical approach. This means that the individual cell lag phase variability of L. monocytogenes has important consequences when studying specific growth cases, especially when the applied inoculum levels are low, but when performing more general exposure assessment studies, the variability between the individual cell lag phases is too limited to have a major impact on the total exposure assessment.