热泵干燥过程PID加Fuzzy温调的应用与实验   总被引：3，自引：0，他引：3  

何书森  陆则坚  王则金 《农业机械学报》1999,30(1):49-53

研究了一种热泵干燥系统,由制冷机的冷凝器提供热量,过程的温控全用ＰＩＤ控制和模糊（Ｆｕｚｚｙ）调节相结合的方法,实验ＰＩＤ调节和ＰＩＤ加Ｆｕｚｚｙ调节进行了比较,证明后者温度过冲减小,振荡减小,过渡时间缩短,恒温平稳,可以达到较满意的效果。  相似文献   

低高径比气体环流生化反应器的研究   总被引：2，自引：0，他引：2  

卢泽民  吴守一 《农业工程学报》1999,15(3):76-81

简要介绍了研究低高径比气体环流生化反应器的目的和方法,采用在反应器内设置特别设计的喷嘴和挡板来提高混合和传质性能,从而反应器的高径比降低到３左右,用气含率、混合和传质特性等性能参数和相同尺寸的机械搅拌反应器进行对比试验,其性能相当。为进一步考察其实用性,设计和生产出２５０Ｌ气体环流反应器,对复合酶进行发酵培养试验。  相似文献   

锤片式粉碎机的理论分析和结构改进措施探讨     

朱新华  郭文川  阎晓利 《西北农林科技大学学报(自然科学版)》1999,27(1):108-111

对锤片式粉碎机的粉碎机理进行了简要分析,从而得出粉碎室内环流是粉碎机大功耗、低效率的主要原因,认为可以通过改变转子结构来降低环流速度,并提出了提高粉碎机的生产率和度电产量的具体措施。  相似文献   

Exploring connectivity between spawning and nursery areas of Mullus barbatus (L., 1758) in the Mediterranean through a dispersal model          下载免费PDF全文

Francesco Gargano  Germana Garofalo  Fabio Fiorentino 《Fisheries Oceanography》2017,26(4):476-497

Connectivity between spawning and nursery areas plays a major role in determining the spatial structure of fish populations and the boundaries of stock units. Here, the potential effects of surface current on a red mullet population in the Central Mediterranean were simulated using a physical oceanographic model. Red mullet larvae were represented as Lagrangian drifters released in known spawning areas of the Strait of Sicily (SoS), which represents one of the most productive demersal fishing‐grounds of the Mediterranean. To consider the effect of inter‐annual variability of oceanographic patterns, numerical simulations were performed for the spawning seasons from 1999 to 2012. The main goal was to explore connectivity between population subunits, in terms of spawning and nursery areas, inhabiting the northern (Sicilian‐Maltese) and southern (African) continental shelves of the SoS. The numerical simulations revealed a certain degree of connectivity between the Sicilian–Maltese and the African sides of the SoS. Connectivity is present in both directions, but it is stronger from the Sicilian–Maltese spawning areas to the African nurseries owing to the marine circulation features of the region. However, because the majority of the larvae are transported to areas unsuitable for settlement or outside the SoS, the dispersal process is characterized by a strong loss of potential settlers born in the spawning areas. These results are in agreement with the low genetic heterogeneity reported for this species in the Mediterranean Sea and support the existence of a metapopulation structure of red mullet in the SoS and the adjacent areas.  相似文献   

太阳能集热器的热流气体对砾石的蓄放热特性研究   总被引：1，自引：0，他引：1  

张文基 《农业工程学报》2005,21(8):126-131

太阳能的蓄放热特性的研究对清洁能源太阳能的开发和利用具有重要意义。该文利用冬季太阳能集热器的热流气体,对砾石的蓄放热特性进行了研究。以居民居住的标准房间（4 m×2.7 m）为依据进行了模拟;利用太阳能集热器的热能与直径为50～100 mm的砾石铺设成150 mm厚度的地下蓄热系统进行蓄热和放热试验,研究昼夜之间室内砾石的蓄热和放热特性;通过测试太阳能集热器的内部温度、砾石层内部及室内地表面的温度,研究了太阳能集热器的蓄热效率和转换效率,同时分析了蓄热层及室内地表面的热传递特性;为进一步开拓针对冬季寒冷地区太阳能蓄热型居民建筑物内部热环境方面的基础研究提供了科学的依据。  相似文献   

新农村建设背景下农地使用权流转研究-基于CGSS农户调查数据的分析     

杨丹  刘自敏 《农机化研究》2010,32(6)

为了研究社会主义新农村建设背景下我国农地使用权流转呈现的新特征,并分析影响农户参与农地使用权流转的因素,利用CGSS(2006)对河北和山西两省共6个区县的农户调查数据进行统计分析,比较了不同区域的农地使用权流转现状和特征差异,以及农户承包的旱地、水田和山林等不同类型的农用地使用权流转情况。在此基础上,分析了影响农户参与农地使用权流转的因素,发现农村劳动力转移、农户对农地经营的依赖、农地分配不均、农业比较收益低下和农业机械化程度的提高等都是影响农户参与农地使用权流转的重要因素。  相似文献   

组芯工艺自动循环装置的研制     

李杰 《拖拉机与农用运输车》2010,37(4):116-118

对组芯工艺自动循环装置进行了研制。生产实践证明,该装置不仅能在本机上实现循环输送功能,而且还能适应多品种缸体和曲轴箱主体芯制芯后的砂芯组合、装配和紧固多工位工作,可满足每小时最少40盒组芯要求。  相似文献   

Updated distribution and host records for the argasid tick Ornithodoros (Pavlovskyella) zumpti: A potential vector of African swine fever virus in South Africa     

Anthony F. Craig  Livio Heath  Jan E. Crafford  Juergen A. Richt  Robert Swanepoel 《The Onderstepoort journal of veterinary research》2021,88(1)

African swine fever virus (ASFV) causes a lethal and contagious disease of domestic pigs. In South Africa, the virus historically circulated in warthogs and ornithodorid ticks that were only found in warthog burrows in the north of the country. Regulations implemented in 1935 to prevent transfer of infected animals or products to the south initially proved effective but from 2016 there have been outbreaks of disease in the south that cannot be traced to transfer of infection from the north. From 1963 there were widespread translocations of warthogs to the south, initially from a source considered to be free of ornithodorid ticks. We undertook to determine whether sylvatic circulation of ASFV occurs in the south, including identification of potential new vectors, through testing extralimital warthogs for antibody and ticks for virus. Results of testing warthogs for antibody and other species of ticks for virus will be presented separately. Here we report finding Ornithodoros (Pavlovskyella) zumpti ticks in warthog burrows for the first time. This occurred in the Eastern Cape Province (ECP) in 2019. Since African swine fever was recognised in the ECP for the first time in 2020 and outbreaks of the disease in domestic pigs continue to occur there, priority should be given to determining the distribution range and vector potential of O. (P.) zumpti for ASFV.  相似文献   

活立木市场交易价格影响因素研究          下载免费PDF全文

邓伟芬  蒋天久  陈明  林露花  吴联杯 《林业调查规划》2023,48(3):188-191

基于2018—2020年浙江省龙泉市900宗活立木交易数据,采用半对数多元线性回归模型研究木材市场价格、单位面积蓄积、林分质量等因素对活立木交易价格的影响。结果表明,龙泉市活立木交易平均价格为3 976元/hm²,木材市场价格、单位面积蓄积、单位面积株数、平均胸径对活立木交易价格有显著的正向影响;流入方性质和流出方性质对活立木交易价格有显著影响,且影响存在差异性。提出规范木材市场交易,加强森林资源评估工作,提升交易的公平性,全面推进林权抵押贷款等建议。  相似文献   

一次持续性区域雾霾天气的综合分析   总被引：9，自引：0，他引：9  

赵桂香  杜莉  卫丽萍  贺耀武  李堂  朱煜 《干旱区研究》2011,28(5):871-878

利用1994年11月发生在山西省的持续性雾霾天气过程实况资料,计算了多种物理量,并从环流形势、形成条件和维持机制等方面进行综合分析。结果表明：①500 hPa锋区偏北,中纬度环流较平,低空850 hPa持续有暖平流向山西地区输送,是大范围霾天气持续的重要天气背景;而500 hPa阻塞形势的稳定维持,地面回流稳定,是导致...  相似文献