特定消谐变频调速实验装置的研制

研制了变频调速原理和特定消谐技术相结合的实验装置,通过控制电路中的模数转换器对存储器高位地址的切换实现变压;改变循环加法计数器的计数脉冲频率实现变频。在逆变电路中采用了三菱公司的智能功率模块,简化了系统结构,提高了整个系统的可靠性和经济性。理论分析和实验结果表明:将特定消谐技术应用于变频调速系统后在节能和环保方面具有优越性能。该实验装置便于分析特定消谐技术的特点和变频调速的运行规律。     

浅谈绿色植保服务与IPM技术应用

本文分析了农产品质量安全问题,主要是农药残留问题,从而提出绿色植保服务即推广生物综合治理(IPM)技术.     

黄芩主要虫害及综合防治

黄芩是河北承德的道地药材,虫害是影响其产量和品质的重要因素之一,本文总结了北方地区黄芩主要虫害的种类、识别要点、发生特点及综合防治技术。     

基于变速积分的无刷直流电机PID控制系统

设计了以TMS320F28335控制器和PM100CLA060智能功率模块为基础的无刷直流电机控制系统,详细介绍了霍尔位置传感器和增量式光电编码器接口电路的设计方案和实现功能.采用变速积分PID控制算法,实现了转速和电流的双闭环调节.该控制系统具有硬件结构精简、调节精度高及响应速度快等特点,便于高效可靠地运行.     

Teaching Future Crop Protection Practitioners through the Use of On-line Cases: Practicing IPM Spray Decisions in New Zealand Apple Orchards

Purpose: There are many complexities to be considered when selecting tactical control options in crops grown under an Integrated Pest Management (IPM) regime. Students being trained in IPM are made aware of this complexity but do not always get the chance to experience IPM decision-making first-hand. This case study describes a web-based assessment and presents student feedback as to its value.

Design/Methodology/Approach: Students are required to analyse the pest and disease status of and provide pesticide recommendations for an export apple orchard at four different times of the season. At each ‘virtual visit’ they are required to interpret monitoring data and make spray decisions. The students are provided with the same IPM information and guidelines commercial growers receive. Amongst other things, management history, non-target organisms, pesticide resistance risk, allowable residues, pesticide restrictions and pesticide compatibility must be considered. Student reflections (n = 57) from three years of use were assessed using grounded theory analysis and reported.

Findings: Students found they gained an appreciation of the various factors that need to be considered for tactical IPM and that the exercise helped prepare them for this task ‘in real life’.

Practical Implications: The assessment described can be used as a template for an online integrated case-based training strategy which provides the opportunity for real-life decision making in a safe environment.

Originality/Value: The paper is original. It is hoped this case study will serve as a source of ideas and/or inspiration from those wishing to employ similar ‘active learning’ web-based exercises for agricultural education or extension training.     

用迭代摄动法求解含立方项强非线性振动方程

采用迭代摄动法求解含有立方项的非线性振动微分方程,得到形式简单的近似解析解.通过讨论解析解在各种情况下的近似程度,说明所采用的方法及得到的简单公式在很大范围内是有效的.     

感应电机解耦控制系统的研究

介绍了一种应用非线性状态反馈对感应电机进行解耦并线性化的交流调速系统。该系统以工控PC作为控制电路的核心部件、以智能功率模块（IPM）组成主电路。给出解耦控制系统的硬件、软件组成及设计方法。实验结果表明，该系统具有理想和动态与静态性能。     

陕西黄芩主要病害及其综合防治技术研究

黄芩作为我国常用的大宗药材品种,家种面积逐渐扩大,随之而来的黄芩根腐病、黄芩根结线虫病、黄芩叶枯病及黄芩白粉病病害面积和程度有逐渐加重的趋势,笔者调查研究了陕西黄芩病害的种类及发病规律,并提出以农业、生物防治为主、必要时采取化学防治的综合防治措施.取得了显著的效果.     

IPM在变频空调中的应用

变频技术是变频空调的核心技术,它不仅能降低噪声,还能提高制冷/热效果和舒适度.而使其拥有较高的可靠性和较低的功耗是由于在变频技术中采用了模块化的功率器件IPM智能功率模块.IPM不但能减少工作噪声,还可以提高系统的可靠性及控制效率.新一代的IPM还改进内部的寄生结构,在低正向压降、高开关速度和宽安全工作区方面进行优化设计,因此在空调和其它的家用电器中得到更广泛的应用.     

Expanding Integrated Pest Management Capacity: Rwanda Case Study

Abstract

Purpose

Rwanda is developing its agricultural capacity to meet the needs of national food security while addressing food demands and requirements of regional and international markets. The Rwanda Horticultural Export Standards Initiative was developed by the Ministry of Agriculture and Natural Resources in collaboration with Michigan State University to strengthen Rwanda's ability to meet both public and private standards for exports of food and agricultural products through capacity building.