液态危险品船舶的远程监视报警系统设计

为了有效监测液态危险品船舶运输过程中液货舱液位、压力、温度和惰性气体含量等安全状态参数的实时状况,采用单片机作为微处理器,设计数据采集与处理模块;基于北斗定位与短报文通信技术,实现船舶数据远程传输,并在B/S架构下开发岸基监控报警管理平台,完成液态危险品船舶远程监视报警系统的研发,最后通过实验平台和实船,对系统性能进行...     

听觉线索引导大鼠空间定位

运用Morris水迷宫实验模式,研究听觉线索在大鼠进行空间定位时的作用.结果显示:听觉线索引导组和对照组动物在4 d内寻找平台的时间和错误率均显著下降.但与对照组动物相比,听觉线索引导组动物寻找隐藏平台的时间和错误率均较低,2组之间具有显著性差异(P<0.05).对动物的轨迹分析发现,听觉线索引导组和对照组动物在水池边缘区域分配的时间不同,提示2组动物寻找平台所用的策略不同.实验结果提示,大鼠能够利用单独的声音线索进行空间定位.     

基于多径瑞利衰落信道的非规则LDPC码分析性能

分析了在静态多径瑞利衰落信道上应用于正交频分复用技术的非规则LDPC码在相同的调制方式,不同的映射模式下的误码性能,并与规则LDPC码的性能作了比较,结果显示,在静态多径瑞利衰落信道上,不同的映射模式下,非规则LDPC码的误码性能均优于规则LDPC码的误码性能,非规则LDPC码在相同的调制方式下,格雷映射的误码性能优于自然映射的误码性能。     

对高校数字图书馆与远程教育服务的思考

针对数字图书馆的特点,分析了数字图书馆在远程教育中具有的优势,探讨了数字图书馆在远程教育过程中存在的不足,论述了数字图书馆在远程教育发展中应注意的诸如设立权威的远程教育管理机构、致力于解决远程教育的"信息孤岛"等问题,提出了加强和改进数字图书馆服务远程教育的策略.     

关于高校图书馆学科导航库建设的思考

阐述了学科导航库的定义与类型,分析了高校图书馆建设学科导航库的意义,针对其发展中存在的读者定位不够明确、类目设置不够规范、信息组织描述不足和更新不及时、检索功能缺乏等问题,提出了几点改进措施。     

Pre-processing for time domain image formation in SS-BSAR system

A pre-processing procedure is designed for a space-surface bistatic synthetic aperture radar (SS-BSAR) system when a time domain image formation algorithm is employed. Three crucial technical issues relating to the procedure are fully discussed. Firstly, unlike image formation algorithms operating in the frequency domain, a time domain algorithm requires the accurate global navigation satellite system (GNSS) time and position. This paper proposes acquisition of this information using a time-and-spatial transfer with precise ephemeris and interpolation. Secondly, synchronization errors and compensation methods in SS-BSAR are analyzed. Finally, taking the non-ideal factors in the echo and the compatibility of image formation algorithms into account, a matched filter based on the minimum delay is constructed. Experimental result using real data suggest the pre-processing is functioning properly.     

转杯速度与成纱质量关系的研究

本文探讨了国产转杯纺纱器的转杯速度与成纱质量的关系,采用经过优化的转杯、隔离盘和假捻盘进行纺纱。试验结果表明,随着转杯速度的提高,成纱质量基本上呈下降趋势。但在杯速为50000 r/min 左右时,成纱质量的几项主要指标最佳。这对于合理设计转杯速度具有一定的参考价值。     

Genetic Algorithms to the Nesting Problem in the Leather Manufacturing Industry

The nesting problem in the leather manufacturing is the problem of placing a set of irregularly shaped pieces (called stencils) on a set of irregularly shaped surfaces (called leathers sheets). This paper presents a novel and promising processing approach. After the profile of leather sheets and stencils is obtained with digitizer, the discretization makes the processing independent of the specific geometrical information. The constraints of profile are regarded thoroughly. A heuristic bottom-left placement strategy is employed to sequentially locate stencils on sheets. The optimal placement sequence and rotation are deterimined by genetic algorithms (GA). A natural concise encoding method is developed to satisfy all the possible requirements of the leather nesting problem. The experimental results show that the proposed algorithm can not only be applied to the normal two-dimensional nesting problem, but also especially suitable for the placement of multiple twodimensional irregular stencils on multiple two-dimensional irregular sheets.     

卫星导航定位系统(二)

介绍了3种卫星定位系统，阐述了美国对伽利略系统的态度及美军空间武器的发展重点。     

综放沿空异形煤柱留巷系统力学场演化规律

研究了不同煤柱宽度时综放沿空异形煤柱锚网支护留巷系统围岩应力分布和破坏特征. 揭示了煤体边缘水平应力和垂直应力峰值不耦合的规律以及巷道顶板应力峰值随煤柱宽度不同而演化的轨迹. 深入探讨了综放沿空留巷岩石力学系统的控制变量,并根据控制变量的取值对系统稳定性区域进行了划分,对不同煤柱宽度时的巷道系统稳定性进行了综合分析和评价,对综放沿空留巷合理护巷煤柱宽度提出了建议. 提出并实施了"以加固沿空异形煤柱为主、悬承锚网支护留巷圈为辅"的综合控制技术.