半导体光放大器的原理及应用分析

半导体光放大器的主要特点是：它由有源区和无源区构成,其放大原理主要取决于有源层的介质特性和激光腔的特性.半导体光放大器可用作线性放大器、波长转换器、光开关和再生器等等.     

基于移动通信网络的农业移动机器人遥操作研究

以农业移动机器人为研究对象,首先介绍了基于移动通信网络的遥操作技术,并基于ARM嵌入式技术,设计了农业移动机器人硬件方案,并从硬件和软件两方面设计实现了该系统.实验结果表明:该系统能够出色地完成任务,满足了预期的效果,具有一定的稳定性和可靠性.     

基于NRF24E1无线奶牛体温数据采集系统设计

奶牛体温是衡量奶牛健康状况的重要参数,定时采集奶牛体温对于判断奶牛的健康状况有着重要意义。人们对于数据传输大多采用有线方式,但牛舍环境不便于铺设线缆进行数据传输。为此,本系统利用收发芯片NRF24E1进行设计,实现了奶牛体温数据采集系统与上位机进行无线通信,满足了对奶牛体温数据实时监测的要求,提高了对奶牛体温数据采集的自动性和高效性。通过芯片的选型以及芯片外围电路的改进优化了硬件电路,并且设计了有效的通信协议,防止传输的数据信号产生畸变并具有自动剔除错误信号的能力。该系统对多头奶牛的体温进行了测量,试验表明,本系统具有较高的实用性和可靠性,成本低功耗低,具有良好的应用前景。     

奶牛场无线传感器网络设计研究

针对奶牛养殖场数据采集时不易实现检测区域的完全覆盖和铺设线缆繁琐的问题,设计了由高性能、低功耗单片机ATmega32L和无线通信模块CRM2400CNC,建立奶牛养殖场无线传感器网络。同时,重点讨论了系统结构、传感器节点的硬软件设计和通信协议等关键问题,结合奶牛场的实际对系统结构的简化进行了研究,并提出了一种新的适合动态网络的跨层技术。试验结果表明,该系统具有结构简单、成本低、功耗低等特点。     

Hygiene-Eliciting Brood Semiochemicals as a Tool for Assaying Honey Bee (Hymenoptera: Apidae) Colony Resistance to Varroa (Mesostigmata: Varroidae)

Despite numerous interventions, the ectoparasitic mite Varroa (Varroa destructor Anderson and Trueman [Mesostigmata: Varroidae]) and the pathogens it vectors remain a primary threat to honey bee (Apis mellifera Linnaeus [Hymenoptera: Apidae]) health. Hygienic behavior, the ability to detect, uncap, and remove unhealthy brood from the colony, has been bred for selectively for over two decades and continues to be a promising avenue for improved Varroa management. Although hygienic behavior is expressed more in Varroa-resistant colonies, hygiene does not always confer resistance to Varroa. Additionally, existing Varroa resistance selection methods trade efficacy for efficiency, because those achieving the highest levels of Varroa resistance can be time-consuming, and thus expensive and impractical for apicultural use. Here, we tested the hypothesis that hygienic response to a mixture of semiochemicals associated with Varroa-infested honey bee brood can serve as an improved tool for predicting colony-level Varroa resistance. In support of our hypothesis, we demonstrated that a mixture of the compounds (Z)-10-tritriacontene, (Z)-8-hentriacontene, (Z)-8-heptadecene, and (Z)-6-pentadecene triggers hygienic behavior in a two-hour assay, and that high-performing colonies (hygienic response to ≥60% of treated cells) have significantly lower Varroa infestations, remove significantly more introduced Varroa, and are significantly more likely to survive the winter compared to low-performing colonies (hygienic response to <60% of treated cells). We discuss the relative efficacy and efficiency of this assay for facilitating apiary management decisions and selection of Varroa-resistant honey bees, as well as the relevance of these findings to honey bee health, pollination services, and social insect communication.     

基于虚拟仿真技术的农机展示和交互设计研究

为了提高农机产品的设计效率和水平,将虚拟仿真和交互展示技术引入到了农机产品的设计制造和展示过程中,通过农机建模、虚拟环境创建和网络发布构建了农机展示系统,有效提高了农机的展示和交流交互效果.在交互展示系统的设计上,采用3 Ds MAX软件创建了农机的三维模型,并在Unity 3 D软件中进行了解析,最后利用Web 3 ...     

21世纪高校图书馆服务新理念

本文从三个方面阐述了服务是图书馆的天职,针对如何创新服务观念,改进图书馆的服务工作提出了自己的观点。     

Design and FPGA Implementation of animproved structure of digital matched filter

An improved structure of digital matched filter(DMF)is presented. Two same pseudorandom spread spectrum sequences with the length of N are used to spread the same baseband symbol at the transmitter, which is equal to spread the baseband symbol with a spread spectrum sequence with the length of 2N. At the receiver, only a spread spectrum sequence with the length of N is needed to de spread the data, and then cumulates the two correlation peaks and exports to the output. The detection probability(Pd)and the false alarm probability(Pf)are analyzed and simulated. The improved structure of DMF is implemented based on the recursive and folded principle. Experimental results show that, for the same spread gain, the improved structure has the same Pd and Pf as the basic DMF, while saves the hardware resources greatly compared with the recursive and folded structure.     

基于低功耗广域网的海岛水产养殖环境监测系统研制

针对海岛环境中水产养殖区域分散、工作环境恶劣、人工巡检不便等问题,设计了基于低功耗广域物联网的海岛养殖环境监测系统。系统包括集成Arduino和传感器的终端采集节点,通过LoRa技术实现数据汇总和远距离传输的汇聚网关,利用Python与PostgreSQL开发用于数据接收、存储、处理、访问和控制的后台监测系统。通过对网络拓扑复杂度、能耗等方面的评估,表明在海岛环境下部署水产养殖环境监测系统,相比传统Zigbee多跳无线传感网,采用LoRaWAN,其单跳节点覆盖范围更大,而网络复杂度、能耗等更优。测试表明该系统能以较低功耗实现整片区域内远距离数据采集,有效传输养殖区水体环境数据。网络生存期与传输可靠性测试表明,当传感器节点采用3.7 V/4 200 mAh锂电池,上传周期为30 min时,监测网络的有效生存期理论上可达2.4 a;在800 m通信范围内,发射功率为20 mW时,节点丢包率小于3.6%,具有较高的通信可靠性。该研究可为水产养殖生产和物联网应用研究提供有效参考。     

地下LoRa无线传感器网络的传输测试系统研究

【目的】以智能手机为核心,研制成本低、使用简单的面向LoRa地下无线数据传输的测试系统。【方法】该测试系统由安装了测试用的App智能手机和与之匹配的地下测试节点组成。利用该系统进行场景测试,测定影响土壤中LoRa无线数据传输效果的因素并讨论对应的数据传输方法。【结果】测试结果表明,该系统运行可靠、使用方便灵活,LoRa低功耗广域网技术亦可以较为可靠地满足土壤介质中的无线传感器网络数据传输需求。【结论】本系统可为未来地下LoRa无线传感器网络的工程应用提供相应的测试手段。