利用交换机解决局域网安全问题

分析了局域网的安全现状,阐述了目前网络安全管理中存在的一些问题,并提出了利用交换机解决的办法.     

Assessing terrestrial wildlife populations in the Toronto and Region Area of Concern

Beneficial use impairments (BUIs) under the Great Lakes Water Quality Agreement identify environmental issues requiring remedial action within the Great Lakes Areas of Concern (AOCs). We conducted this study to support the assessment of the wildlife component of BUI 3: degradation of fish and wildlife populations. We compared bird and amphibian (frogs and toads) data from the Toronto and Region Conservation Authority’s Terrestrial Long-term Monitoring Program in the Toronto and Region AOC to an adjacent, but otherwise similar, reference watershed, Duffins Creek. Twelve of 13 targets were met within the AOC for forest bird, wetland bird, meadow bird and amphibian populations based on averages of mean annual values at sites within the AOC that were within two standard deviations of averages at sites in the Duffins Creek reference watershed between 2008 and 2017. Even though wildlife populations within the AOC were within the normal range of variability expected from a reference watershed, they were often at lower levels than within the Duffins Creek reference watershed. In addition, forest bird and amphibian populations were negatively affected by urbanization within the AOC and meadow bird indices declined. We conclude that while wildlife populations within the AOC currently meet targets for BUI 3, they continue to be negatively impacted by numerous stressors that are primarily related to past and ongoing urbanization. Thus, continued restoration of wildlife habitat and protection of existing habitat within the AOC is highly recommended.     

Towards improving an Area of Concern: Main-channel habitat rehabilitation priorities for the Maumee River

The Maumee River watershed in the Laurentian Great Lakes Basin has been impacted by decades of pollution and habitat modification due to human settlement and development. As such, the lower 35 km of the Maumee River and several smaller adjacent watersheds comprising over 2000 km² were designated the Maumee Area of Concern (AOC) under the revised Great Lakes Water Quality Agreement in 1987. As part of pre-rehabilitation assessments in the Maumee AOC, we assessed fish and invertebrate communities in river km 24–11 of the Maumee River to identify: 1) areas that exhibit the highest biodiversity, 2) habitat characteristics associated with high biodiversity areas, 3) areas in need of protection from further degradation, and 4) areas that could feasibly be rehabilitated to increase biodiversity. Based on benthic trawl data, shallow water habitats surrounding large island complexes had the highest fish diversity and catch per unit effort (CPUE). Electrofishing displayed similar fish diversity and CPUE patterns across habitat types early in the study but yielded no discernable fish diversity or CPUE patterns towards the end of our study. Although highly variable among study sites, macroinvertebrate density was greatest in shallow water habitats <2.5 m and around large island complexes. Our results provide valuable baseline data that could act as a foundation for developing rehabilitation strategies in the lower Maumee River and for assessing the effectiveness of future aquatic habitat rehabilitation projects. In addition to increasing in-channel habitat, watershed-scale improvements of water quality might be necessary to ensure rehabilitation strategies are successful.     

Performance and cost trade-off in Tracking Area reconfiguration: A Pareto-optimization approach

Tracking Area (TA) design is one of the key tasks in location management of Long Term Evolution (LTE) networks. TA enables to trace and page User Equipments (UEs). As UEs distribution and mobility patterns change over time, TA design may have to undergo revisions. For revising the TA design, the cells to be reconfigured typically have to be temporary torn down. Consequently, this will result in service interruption and “cost”. There is always a trade-off between the performance in terms of the overall signaling overhead of the network and the reconfiguration cost. In this paper, we model this trade-off as a bi-objective optimization problem to which the solutions are characterized by Pareto-optimality. Solving the problem delivers a host of potential trade-offs among which the selection can be based on the preferences of a decision maker. An integer programming model has been developed and applied to the problem. Solving the integer programming model for various cost budget levels leads to an exact scheme for Pareto-optimization. In order to deliver Pareto-optimal solutions for large networks in one single run, a Genetic Algorithm (GA) embedded with Local Search (LS) is applied. Unlike many commonly adopted approaches in multi-objective optimization, our algorithm does not consider any weighted combination of the objectives. Comprehensive numerical results are presented in this study, using large-scale realistic or real-life network scenarios. The experiments demonstrate the effectiveness of the proposed approach.     

基于FIRA仿真足球守门员的决策设计

研究FIRA机器人足球守门员的准确性站位设计。由于守门员站位不精确,导致失败。为了提高守门员对于小球危险程度判断的准确性及其站位的精确性,提出了以球门线为公共弦长、不同半径大小的圆形区域来划分场地,提取小球、场地和守门员的综合信息,通过小球与球门线的距离、射门角度以及速度判断场地区域的危险等级,进而采取不同的防守策略。同时提出一种新的基于"角平分线—中点连线中点"站位方法,综合运用其它不同的站位法来修正守门员最佳位置,结合守门员的动作模型实现快速、准确、高效的防守。实验结果表明,证明防守策略提高了守门员防守的成功率,为足球仿真平台的设计提供了依据。     

区位码/国标码输入法技术初探

计算机技术领域中,使用键盘输入汉字的方法实质是区位码/国标码输入法。本文介绍了区位码/国标码输入法的现实意义,IME的组成结构以及区位码/国标码输入法的发展动态。主要说明区位码/国标码输入法在中文键盘输入法的重要地位,并简单分析了中文键盘输入法编辑器的组成结构等技术。     

真空压铸的发展

真空系统是压铸过程中排除气体的最有效的方法之一。然而，真空压铸的发展几经起伏，现在则发展到一个新的阶段。从模具中抽出气体是几种抽气方法中较为简便的一种。真空气道的设计与常规气道则有所不同     

列车用CAN协议一致性测试平台的设计与实现

列车用CAN总线协议一致性测试是保证不同设备制造厂家生产的CAN通信设备之间实现互联、互通和互操作的前提。在对协议一致性测试原理和CAN总线协议特点进行简要分析的基础上,提出了针对CAN总线协议一致性测试的协同测试方法和相应的一致性测试内容,设计并构建了相应的一致性测试硬件平台,并对测试软件平台中可执行测试实例产生、测试执行、测试评估以及测试管理等诸多环节所涉及的基本功能软件进行了设计和实现,完成了CAN协议一致性测试的基本功能。实际运行和测试结果表明：所设计的测试平台达到了预期结果,为下一步列车用CAN总线协议的一致性测试打下了基础。     

Enhanced utilization bound of Rate-Monotonic scheduling in Controller Area Networks

When priorities to message streams are assigned using Rate Monotonic (RM) for a Controller Area Network (CAN), the utilization bound is known to be about 25% for CAN 2.0A and 29% for CAN 2.0B. In this letter, we present a higher utilization bound than the existing ones with a reasonable constraint. The new utilization bounds are approximately 34% for CAN 2.0A and 41% for CAN 2.0B if no single message stream's utilization exceeds 46% or 27% of the total utilization for CAN 2.0A or CAN 2.0B, respectively.     

促进三峡库区和谐稳定发展评价方法研究

三峡库区已完成了百万移民的搬迁安置,进入了移民安稳致富的新阶段,库区社会和谐稳定对促进库区经济社会健康发展和实现全面建成小康社会的目标具有重要作用。本研究重点关注和谐库区建设思路及评价指标体系构建:一方面,从理论层面,重点论述与库区和谐社会相关的理论认识成果;另一方面,从实际管理运用层面,构建了库区和谐评价指标体系,可为移民动态管理提供有力的技术支撑。