具有负载扰动时晶闸管直流调速系统的最优设计     

常恕吾 《东北林业大学学报》1991,(6)

本文以状态空间分析法介绍了工程上普遍应用的晶闸管直流双环调速系统,基于二次型最优控制的状态调节器的设计方法,给出了模拟电路,实验表明,采用状态反馈和扰动前馈补偿的最优控制,使系统性能比用经典理论设计的调节器优越。  相似文献   

摩洛哥脐血橙植株上一种机械传播性病毒的鉴定   总被引：2，自引：0，他引：2  

陈国庆  王洪祥 《植物病理学报》1997,27(4):365-368

 本文采用叶片接种法和枝条接种法对25个柑桔种类体细胞杂种或品种进行了抗脚腐病鉴定,结果表明:体细胞杂种中枳+酸橙、枳+甜橙为高抗类型;酸橙+兰普来檬、枳+印度酸桔;蚝壳刺+哈姆甜橙、酸橙+澳洲指桔为抗性;酸橙+印度酸桔为中抗。建立了叶片接种法的抗病性分级标准。初步分析了柑桔体细胞杂种的抗性规律。  相似文献   

状态空间迭代法计算拱坝的动力响应     

田洪臣  黄胜伟 《山东农业大学学报(自然科学版)》2001,32(3):327-330

应用现代控制论中的状态空间理论，将坝体位移作为状态变量，导出拱坝动力响应分析的状态方程，建立状态空间迭代法的计算格式。由于状态空间法可同时算出各种应力和位移量，因此，应力与位移的精度较高。文要给出了一个拱坝动力响应问题的算例，所得计算结果与其它方法作了比较。  相似文献   

《国家安全法》试点教学的探索和思考     

张玉兰  徐秀勇  徐毓马 《金陵科技学院学报》2001,17(2):100-104

总结了我校开展《国家安全法》试点教学实践的基本做法 :做好三方面的准备工作 ;重点抓好课前、课堂、课后三环节 ;采取多种辅助教学形式 ;进行教学教研。在实践的基础上提出了一些理性思考。为《国家安全法》的普及与推广提供了经验。  相似文献   

东北,内蒙古国有林区林业发展潜力的研究——营林业发展潜力     

王永青  杨长峰 《东北林业大学学报》1997,25(4):42-46

研究林业发展潜力是正确确定林业发展规模和水平，建立林业多产业和合理的产业产品结构的重要依据，是制定林业发展战略和林业的重要前提。文章从林地利用和林地生产力两个方面研究了东北、内蒙古国有林区林业发展潜力，通过多方案优化分析表明，该区林地利用林地生产力具有巨大的发展潜力，并针对营林业发展潜力的挖掘提出了具体的建议；搞好林地利用的规划和设计；加强经营管理，转换经营方式；加强资金投入，扭转目前资金投入不  相似文献   

Nutrient and nutritional evaluation of sinasin prepared in two ways     

Elizabeth C. Chibuzo  Fati A. Godowoli  Rose J. Kure 《Plant foods for human nutrition (Dordrecht, Netherlands)》1996,49(2):139-145

Two types of sinasin, a rice-based fermented kanuri flat bread, were prepared and evaluated for their nutrient content and nutritional qualities. The preparation of the sinasin entailed using traditional and developed methods. The nutritional qualities of the products were evaluated in Wistar-strain albino rats using the Food Efficiency Ratio (FER), and Protein Efficiency Ratio (PER) methods. There was a higher protein content (11.11 percent) in the traditional sinasin than in the developed sinasin (9.93 percent). However, a one-way analysis of variance indicated no significant difference in FER, but a significantly different mean PER (p<0.01) of 1.3 and 1.5 for the traditional and developed sinasin respectively. The two methods of preparation of the sinasin, their nutrient composition and nutritional qualities are described in this paper.  相似文献   

A Review of “The Heirloom Tomato: From Garden to Table Recipes,Portraits, and History of the World's Most Beautiful Fruit”     

Tom Volkening 《Journal Of Agricultural & Food Information》2013,14(3):267-268

This study examined wetland farming systems in Edo State, Nigeria, with specific focus on practitioners’ response to Fadama technologies, as well as factors that might promote adoption behavior. Primary data were sourced from 301 wetland farmers across the three political districts in the state. Responses were analyzed using frequency distribution and multiple regression. Fertilizers, herbicides, insecticides, and improved varieties were the most adopted technologies; cost was the most serious constraint to adoption. The average earnings derived from wetland farming enterprises were 291,400.28 (US$1,942.60) per annum. Important determinants of wetland farming technology adoption by farmers include education, contact with extension agents, revenue, and credit. The study recommends an improvement in Fadama farmers’ access to credit and extension services.  相似文献   

Perception of the Influence of Home Videos on Youth Farmers in Makurdi,Nigeria     

Emmanuel Chukwunyem Odiaka 《Journal Of Agricultural & Food Information》2013,14(4):337-346

This study examined the effects of home video on youth farmers. Data collected from 175 randomly selected farmers in Makurdi using a structured questionnaire showed 84.6% watch at least once a week; 77.1% watch between 4–10 p.m. Farming is portrayed as tedious and unprofitable. The effects are reduced interest in farming (90.3%), rural-urban migration (66.9%), and abandonment (57.1%). The chi-square test showed significant influence of home videos on male youth farmers (χ² Cal = 102.14 ≥ χ Tab = 3.84, p =.05). The study recommends collaboration between food stakeholders and moviemakers to inject positive agricultural messages to stimulate interest among youth farmers for improved agricultural production and sustainability.  相似文献   

Demographic Survey of Tree Species in Urban Centers of Ekiti State,Nigeria     

Joshua Kayode 《Journal of Sustainable Forestry》2013,32(5):477-485

A combination of social surveys and direct field observations was used to identify and enumerate the tree species that are presently planted in and around the urban centers in the three zones of Ekiti State, Nigeria. A total of 62 tree species belonging to 27 families were sampled as urban tree species in the study area. Products derived from these trees ranged from edible fruits, cash income, medicine, fuel, shade, and wind control. The various similarity measures revealed that similar species of trees occurred as urban tree species in the three zones of the study area. Interviews with the various respondents revealed that all of them were tree minded irrespective of their sex, age, educational, economic, and religious status. Thus, these features were not regarded as prerequisites to tree mindedness in the study area. Field observation revealed that urban forestry is still poor in the state and at present the products derivable from the trees influenced the choice of species planted by the respondents. Thus, the various advantages derivable from the urban tree species, coupled with the tree mindedness of the respondents, could be utilized to serve as viable incentives to tree cultivation—especially in Nigeria where previous efforts had concentrated on farm and industrial forestry.  相似文献   

柴油品质对非道路移动机械用柴油机性能的影响     

李旭聪  邹强  姚春德 《拖拉机与农用运输车》2012,39(5):51-54

以一台四缸非道路移动机械用柴油机为试验发动机,采用不同燃料品质的柴油为燃料在发动机台架上进行发动机动力特性、经济特性以及排放特性试验研究。其研究结果显示:国三柴油在柴油机上应用的动力性与普通柴油差别不大,仅在大转矩时优于普通柴油;其经济性明显优于普通柴油,燃油消耗率最大可降低将近7%;国三柴油燃烧后的排放物CO、HC、NOx、烟度以及PM均有不同程度的改善。  相似文献