基于3G通信技术的现代图书馆工作新思路

3G移动通信技术所具有的高带宽、高数据传输率为现代图书馆的发展提供了新的历史机遇和挑战,传统的数字图书馆在基础设施、管理架构和服务模式等方面已经远远不能满足3G时代读者的个性化需求,因此对传统图书馆进行3G适应性的改造势在必行。结合3G移动通信的技术特征和传统图书馆的不足提出新环境下图书馆工作的新思路。     

P2P网络传输协议浅析

本文从C/S与P2P传输方式的区别入手,讨论了P2P的发展历程,分析P2P的基本工作原理与多点传输的信息共享方式的优势所在,每个用户既是客户机同时又是服务器,极大的提高网络下载速度,丰富了网络资源,并对当前的P2P技术在人们日常生活中的各方面应用作了简要介绍。     

基于GSM和WSN的温室环境监控系统设计

针对温室环境监控的应用需求,设计了一种基于GSM无线技术和无线传感器网络(Wireless Sensor Network,WSN)技术的智能温室监控系统。该系统以GSM网络为远程通信平台,以无线传感器网络作为监测和近距离通信平台;采用ARM9微处理器和MSP430单片机为核心构建系统硬件平台实现对温室环境的远程监控。该系统具有操作简单、可扩展性强和装设灵活等特点,是一种实现智能监控温室环境的有效途径。     

Sustainable Aquaculture Products: Implications of Consumer Awareness and of Consumer Preferences for Promising Market Communication in Germany

Sustainability issues are becoming increasingly important in Western food consumption. This research aims at identifying ways to increase the market share of sustainable fish from aquaculture by analyzing consumer awareness and preferences for sustainable aquaculture products and by drawing conclusions on improving communication in the German market. An integrative research approach was used: it began with an inventory of sustainable seafood products on the German market, followed by qualitative and quantitative consumer research, and ending with a stakeholder workshop, which reflected on the research outcome with practitioners. Sustainability and country of origin proved to be of minor relevance to the vast majority of the consumers interviewed. Indeed, attributes such as freshness, taste, and price frequently ranked higher. Like most of the other consumers, the small consumer segment that is generally interested in sustainability issues of food also often lacks knowledge of fish farming and its products. Consequently, communication of sustainability in aquaculture is challenging, and the development of this market requires concerted actions along the whole value chain, with the retail sector as the main actor.     

生猪养殖阶段可追溯系统的天线设计

[目的]针对生猪养殖阶段特点,设计基于RFID技术的畜产品可追溯系统。[方法]阐述电子标签和读写器的天线设计方法,并采用不同的天线对可追溯系统进行通信测试。[结果]数据传输率等参数设置相同时,外接天线的通讯距离比PCB天线要远;3种外接天线比较而言,同轴天线和壁挂天线的通讯距离较远;500kbps数据传输卒时通讯距离在28m范围内,250kbps数据传输率时通讯距离在40m范围内。从硬件成本角度考虑,壁挂天线价格远高于同轴天线,在相同通讯距离要求时,系统选用同轴天线。[结论]在生猪养殖阶段采用该研究设计的有源电子标签和读写器,可提高猪肉产品的安全性,并对彻底实现食品的“源头”追踪和提供食品安全的透明化管理提供技术支撑。     

基于PC机的自动恒压供水系统

介绍了基于PC机的自动恒压供水系统。该系统根据供水管网的水压、水位、流量等参数，调整水泵的投入台数及转速，实现全自动恒压供水。给出了恒压供水系统的硬件组成框图及工作原理，根据系统功能要求，重点介绍了PC机与MCS-51单片机的串行通信原理。用VB语言设计了系统的上、下位机之间的数据通信、过程控制的显示和数据处理等程序。本控制系统具有工作稳定、人机界面好、系统扩展能力强和操作简便等特点。     

工业通信网络实时性的分析

实时性问题在工业通信网络中具有十分重要的地位,本文首先介绍了工业通信网络实时性的概念以及影响通信网络实时性的几个要素,进而列举了网络实行性问题的对象模型,并且对模型做了深入的分析,阐述了满足网络实时性要求的各方面因素,有利于大家对不同的工业通信网络进行网络实时性问题的分析.     

串口的调试和软件实现

本文对船舶中使用设备的串口通讯的硬件、软件实现和调试进行了深入的讨论 ,虽然用的是船舶中的例子 ,但所述的方法是通用的。     

Optimization of experimental infection protocols for the estimation of genetic parameters of resistance to White Spot Syndrome Virus (WSSV) in Penaeus (Litopenaeus) vannamei

Two infection protocols, individual oral (IO) and waterborne infection (WB), were evaluated to challenge Penaeus (Litopenaeus) vannamei with White Spot Syndrome Virus (WSSV). Five different batches of full and half-sib families were infected experimentally and tested for growth performance under commercial growth conditions. The genetic variance for WSSV resistance was estimated using a linear sire-dam repeatability model that considers test-day survival as the dependent variable. The heritability estimates using the IO protocol ranged from 0.01 ± 0.00 to 0.02 ± 0.01, whereas the heritability estimates using the WB infection protocol were not significantly different from zero. The genetic correlations measured as the product moment correlation between full-sib family breeding values for resistance to WSSV and harvest body weight in ponds were unfavourable in three of the five batches and favourable in one of them. The dosage of WSSV was better controlled with IO oral infection than with other methods, with all animals being exposed to approximately the same risk of infection at the same time. This should improve the accuracy of the genetic parameters and hence improve the accuracy of the breeding values. It should, however, be noted that once the outbreak was established and the mortalities began, the shape and the magnitude of the slope of the mortality curves showed little difference in the infection pattern between batches irrespective of the dosage and infection protocol, and in most of the cases the cumulative mortality was greater than 80%. The main reason for this is probably the high densities of animals in the tanks needed for the genetic evaluations.