网式散叶密集烘烤下部烟叶失水规律与烘烤效应关系研究

为明确网式散叶密集烘烤过程中不同装烟层烟叶的失水规律及其与烟叶烘烤效应的关系,采用称重器对气流上升式密集烤房网式烟框装烟下部叶烘烤过程中失水量进行了实时测定,并考查烘烤过程中烟叶外观性状变化及烤后烟叶质量性状。结果表明:(1)烘烤过程中上、中、下三层烟叶失水率均呈Logistic曲线变化规律,在干筋期以前烟叶失水率下层明显大于中层,中层明显大于上层;(2)不同层次烟叶失水速率均呈"先上升后下降"的"∧"型变化趋势,全炕烟叶的平均失水率与中层烟叶接近;(3)各层烟叶失水变化规律及烟叶外观性状变化与烘烤过程中温湿度变化、烘烤时间的关系密切,对烟叶外观质量和内在质量都有影响。     

市、县、乡、村四级网络联动探索农村信息服务模式

本文对我国推进农村信息化的意义和当前发展现状进行了阐述,指出日前我国农村信息服务体系建设中存在的问题,作者以济南市在实施农村信息化工程中的对策和效果为研究对象,全面阐述和分析了“市、县、乡、村”四级网络联动的农村信息服务模式,同时用实例说明了全面推进农村信息化对缩小城乡之间的“数字鸿沟”和拉近城乡之间“知识文明”距离的作用。     

林业有害生物基层监测网络的建设与管理

本文通过对达县国家级森林病虫害中心测报点的监测网络体系及其管理方法的分析,对有关林业有害生物基层监测网络建设与管理等问题进行了阐述。     

亲近阅读 亲近图书馆

当今网络正深刻地影响着人们的学习和工作,与此同时也带来了“浅阅读”、“阅读危机”等现象。本文在此背景下阐述了提倡“亲近阅读”、“亲近图书馆”的价值和意义,以及图书馆在全民阅读活动中应扮演的角色。     

基于BP神经网络的农机总动力预测模型研究

利用黑龙江省1980～2007年农机总动力数据,对BP神经网络模型和现有农机总动力预测模型进行分析,建立了基于BP神经网络的农机总动力预测模型,并将该模型应用到2007年以后黑龙江省农机总动力的预测中,取得了良好的预期效果,为黑龙江省的农业机械化发展趋势和农机产品市场分析提供了一定的理论指导。     

面向新农村建设的远程教学资源与网络平台整合研究

根据新农村建设中新型农民教育发展的要求,分析了教学资源建设的有关问题,明确了网络教学资源建设的内涵,给出教学资源建设和教学平台建设的关系,指出支撑教学和学习的平台软件是一种资源,而加强对组员的分析和组织是构建网络教学平台的关键,并提出了利用XML进行数据建模以及基于Struts＋Spring＋Hibernate架构实现网络教学平台等有关技术思路。     

都市型现代农业走廊网络服务系统的设计与实现

对京承农业走廊区域内空间信息资源管理、农产品供求、观光农业、农业技术推广、土地利用监测和农业生态评价等方面的问题进行深入分析研究,运用网络地理信息技术,建立基于WebGIS的都市型现代农业走廊网络服务系统。系统包括走廊管理、园区动态、技术示范、供求信息和观光农业等模块,采用土地利用动态变化、生态服务价值量和景观生态丰度等模型,对京承农业走廊内的土地利用变化、景观和生态效益进行分析评价,解决了上述在农业走廊区域内农业发展转变过程中所要面临的问题;系统化地构建了为农民、消费者、经销商和管理部门等提供信息、技术和服务的网络平台,以提高都市型现代农业的科学化管理、规划和实施水平。     

Wireless sensor network deployment for integrating video-surveillance and data-monitoring in precision agriculture over distributed crops

Monitoring different parameters of interest in a crop has been proven as a useful tool to improve agricultural production. Crop monitoring in precision agriculture may be achieved by a multiplicity of technologies; however the use of Wireless Sensor Networks (WSNs) results in low-cost and low-power consumption deployments, therefore becoming a dominant option. It is also well-known that crops are also negatively affected by intruders (human or animals) and by insufficient control of the production process. Video-surveillance is a solution to detect and identify intruders as well as to better take care of the production process. In this paper, a new platform called Integrated WSN Solution for Precision Agriculture is proposed. The only cost-effective technology employed is IEEE 802.15.4, and it efficiently integrates crop data acquisition, data transmission to the end-user and video-surveillance tasks. This platform has been evaluated for the particular scenario of scattered crops video-surveillance by using computer simulation and analysis. The telecommunications metrics of choice are energy consumed, probability of frame collision and end-to-end latency, which have been carefully studied to offer the most appropriate wireless network operation. Wireless node prototypes providing agriculture data monitoring, motion detection, camera sensor and long distance data transmission (in the order of several kilometers) are developed. The performance evaluation of this real tests-bed scenario demonstrates the feasibility of the platform designed and confirms the simulation and analytical results.     

基于遗传算法优化BP神经网络的小球藻生长模型的建立与应用

[目的]探讨用遗传算法优化BP神经网络对小球藻生长模型的建立与应用。[方法]使用遗传算法对BP神经网络的权值和阈值进行优化,并使用该网络模型,以小球藻培养时间和残余葡萄糖为输入,菌体光密度值（OD680）为输出,对小球藻在500 L多功能生物反应器中的生长情况进行了建模,还探讨了该模型的应用情况。[结果]经过遗传算法优化的BP神经网络,其泛化值的误差平方和比BP神经网络的小,因而预测值更加接近实际值。t检验表明,所建立的模型是可信的。验证表明,该模型具有良好的拟合度,能够很好地描述在500 L多功能生物反应器中培养的小球藻的生物量（OD680）与残余葡萄糖和培养时间之间的关系。[结论]所建立的模型可用于试验结果的预测,对小球藻的培养控制具有指导意义。     

Gas composition of baled grass silage as influenced by the amount,stretch, colour and type of plastic stretch‐film used to wrap the bales,and by the frequency of bale handling

The effectiveness of the polyethylene stretch‐film barrier to air infiltration is the major factor affecting the preservation of silage in bales. Three separate experiments investigated the effects of the number of layers of stretch‐film cover, film colour, stretch extent, film type and frequency of bale handling on gas composition, surface mould growth and conservation characteristics of baled grass silages. Monitoring gas composition in bales during ensiling proved useful for assessing the success with which wrapped bales were stored anaerobically. Under good storage conditions the early stages of ensiling were characterized by the rapid reduction of O₂ concentration in the bale and the creation of a CO₂‐rich environment. However, wrapping bales in only two layers of stretch‐film failed to create the anaerobic conditions required for a successful fermentation and the inhibition of visible fungal growth. In contrast, a minimum of four layers of stretch‐film were required to achieve suitably anaerobic conditions, but the additional benefits of applying more layers were relatively small. Under temperate climatic conditions with moderate solar radiation, film colour had little effect on the gas composition in baled silage. Likewise, the extent of stretching applied to the film at wrapping and film type had no influence on gas composition, baled silage quality or mould development. However, frequent mechanical handling of bales after wrapping had a negative effect on gas composition and surface mould growth, and thus should be kept to a minimum.