分叉角与回转半径对双向流道灌水器水力性能影响模拟研究          下载免费PDF全文

王亚林  符剑平  吕从聪  钟韵  朱士江 《干旱地区农业研究》2024,(1):270-277

为研究双向流道灌水器水力性能，将其结构单元作为研究对象，以分叉角和回转半径两个结构参数为影响因素，采用正交试验设计16种结构参数组合方案，利用计算流体动力学软件Ansysfluent对流道内部流体的流动状态进行数值模拟，通过量纲分析建立流道结构参数与流道单元局部水头损失的回归模型。结果表明：双向流道单元局部水头损失与分叉角、回转半径和流道流速有关，分叉角与局部水头损失呈负相关关系，回转半径和速度与局部水头损失呈正相关关系；当入口流速为固定值时，分叉角为32.4°、回转半径为1.72 mm，流道单元局部水头损失最大；当设置10个流道单元时，交叉排列方式组合的灌水器流态指数较优。  相似文献   

云南地方栽培木豆群体数量性状变异分析   总被引：2，自引：0，他引：2       下载免费PDF全文

李正红  潘学政  周朝鸿  谷勇  刘秀贤  惠雅玲 《林业科学研究》2004,17(5):547-554

对云南省8个地方栽培木豆群体进行调查,对木豆株高、地径、冠幅、单株荚数、虫荚率、单株粒质量及百粒质量等数量性状变异进行分析,结果表明7个性状不论是群体间还是群体内个体间均存在丰富变异。性状相关性分析表明,单株粒质量与单株荚数呈高度正相关,与株高、地径呈弱正相关。单株荚数、虫荚百分率、百粒质量对产量构成贡献最大,通径系数分别为0．8551、-0．2374、0．1799。若将三个性状相结合,选择单株荚数多、粒大、虫荚少的单株,则后代产量可望有明显增加,有可能育成高产高抗虫性品种。  相似文献   

福建乡土野生绿化树种种质资源调查研究   总被引：4，自引：0，他引：4  

黄云鹏 《林业资源管理》2005,(6):74-77

通过对福建省各主要山脉乡土野生绿化树种种源分布状况调查,首次确定福建省观赏价值较高的乡土野生绿化树种有47科62属105种。并根据树种观赏价值划分为:观花植物、观果植物、垂直绿化植物、丛植观花植物、观叶植物、观形植物、盆景绿篱七大类。为充分开发利用当地资源和保护野生绿化树种种质提供科学理论依据。  相似文献   

试论园林文态建设     

郭燕舞  林汉 《湖北林业科技》2005,(5):56-58

文章从3个方面论述了对“园林文态”的理解,并进一步阐明在当今园林建设实践中,实现“园林文态”的途径。  相似文献   

对地方标准法律属性的探讨     

姚贵宝  王立海  任增杰  周次林 《森林工程》2007,23(5):74-77

研究地方标准的法律属性将有利于地方标准的发展和转型。从地方标准的法制性及法律规制属性两个方面来阐述地方标准的法律属性,从而进一步完善地方标准理论,促进地方标准的发展。  相似文献   

Conducting surveys on forestry attitudes and practices in Leyte communities,Philippines: Experiences and lessons learnt     

Edwin D. Cedamon  Nick Emtage 《Small-Scale Forestry》2005,4(1):69-84

A survey of forestry practices and attitudes was undertaken in four communities in Leyte, the Philippines, to improve understanding of the social and economic factors affecting small-scale forestry development. The survey had three main data collection activities — initial focus group discussions (FGDs), household interviews, and reporting and validation FGDs. A team of enumerators was selected for household interviews which consisted of both males and females, to avoid potential problems of unwillingness of people to talk with those of the opposite gender. The interviewers were also required to be able to speak local dialects (Cebuano and Waray Waray), the survey questionnaires being administered in these dialects. Various methods were used to gain the support and assistance of local government units and barangay captains. Some difficulty was experienced by the survey team in the first community due to barangay elections at the time of the survey, and the requirement by the University of Queensland Ethics Committee that respondents sign a consent form. This requirement was found to be not culturally appropriate for the Leyte smallholder communities. Offering goods at the end of the interview was found to be of limited value for encouraging participation in the survey. Provision of food and drinks were found to encourage FGD participants to express their views, but too much alcohol had a negative effect. The importance of providing comprehensive feedback to respondents and involving them and other stakeholders in development of policy recommendations was apparent. These survey experiences provide valuable insights which are not generally available in textbooks on sample surveys, and provide lessons for planning and conducting smallholder community survey into natural resource management issues.  相似文献   

People’s attitude and use of forestland: Co-evolution of forest administration in Bangladesh     

Mohammad Ali  M. Alamgir Kabir  A. T. M. Rafiqul Hoque 《Small-Scale Forestry》2006,5(2):271-286

This paper explores the influence over time of past policies on people’s attitudes towards the use of forestland in Bangladesh. The discourses of the attitudes of people were captured from the observed social tradition towards forest resources. Forests were reserved systematically and solely through the Forest Department. The conservation processes were not participatory, and rights and tenure were strictly controlled. People were socially excluded and alienated from the forest, and the socio-political factors stimulated negative attitudes among people. Forests were considered to be government property, and therefore managing forests was the responsibility of the government. People only used forest resources to meet their own requirements, either with formal permission or illegally. This situation continued even after the independence of Bangladesh in 1971. As a result, the forests of Bangladesh have been degraded heavily in recent decades.  相似文献   

强化基层林业站职能作用 促进林业跨越式发展   总被引：2，自引：0，他引：2  

周戡 《林业资源管理》2002,(3):6-8

基层林业站是国家设在基层的林业管理机构 ,在林业生产和建设中发挥着重要的职能作用。强化林业站的职能作用 ,必将对推动我国六大林业重点工程建设 ,实现林业跨越式发展起到巨大作用。  相似文献   

立地对西南桦不同种源生长的影响   总被引：1，自引：0，他引：1  

林玉清  黄伟强  陈国彪  薛瑞山  陈志敏 《福建林业科技》2007,34(2):5-9,40

25个种源在3种不同立地造林的结果显示:立地对西南桦生长影响大,3种立地幼林胸径、树高、材积生长差异显著。在好立地上西南桦胸径、树高、材积生长量比中等立地分别大2.3%~25.8%、15.1%~56.4%、27.6%~173.2%;中等立地比差立地大1.0%~53.3%、-9.9%~32.6%、14.0%~155.1%。3种立地上的西南桦不同种源胸径、树高、材积的生长有差异,最大与最小之间差异分别是1.60 cm、1.0 m、0.003 71 m3。  相似文献   

地方特色植物在昆明的适应性调查研究   总被引：1，自引：1，他引：1  

梁屯  董琳 《林业调查规划》2004,29(3):95-99

通过世博园中国园区在设计及建设中地方特色植物的应用分析，得出了地方特色植物在造园时均受到重视的结论，并实际调查造园植物的生长状况，初步掌握各省区地方特色植物在昆明的适应性。经植物区系分析，探讨地方特色植物的异地利用问题，为昆明园林建设中观赏植物的应用提供借鉴和参考。  相似文献