含刚性沉水植物明渠水流结构的试验研究     

王子建  丁雪  吉庆丰 《灌溉排水学报》2020,(2):78-83

【目的】得到含刚性沉水植物明渠的水流结构。【方法】采用粒子图像测速仪(PIV),用有机玻璃棒模拟刚性植物,在不同来水流量、植物密度条件下对明渠水流结构进行了试验研究。【结果】无植物时平均流速沿垂向呈对数分布规律,有植物时则呈现明显的分区分布特性。无植物时紊动强度值沿垂向变化不大,有植物时在植物顶端位置处紊动最剧烈。流量或植物密度越大,植物顶端位置的流速梯度就越大,植物层上方的流速最大值也越大。植物密度越大,植物顶端位置的紊动强度越大,植物密度对水流紊动强度由最大值减小到最小值的区域影响很大。【结论】刚性沉水植物的存在会改变水流结构,增强紊动掺混,增强流体质点交换和能量传递,且上述影响会随着流量或植物密度的增大而增强。  相似文献   

开口薄壁结构弯扭屈曲能量原理的有限变形理论分析     

舒兴平  王世纪 《湖南农业大学学报(自然科学版)》1991,18(3)

The formulas of the total potential energy of arbitrary thin- walled open cross section member counting in the geometric non-linear factors is deduced. The deductions are based on the most general finite deformation theory and the two assumptions that"the  相似文献   

绿道在城镇密集区的应用     

申治琼  罗言云  卿人韦 《北方园艺》2011,(23):77-80

在分析绿道理论作为线性廊道重组自然空间的基础上,以金堂公园东区为例,提出3种类型绿道的设计途径和方法,包括边缘区绿道、自行车骑游道及游步道,使金堂公园东区形成完善的绿道网络系统.绿道的交通组织、生态、文化、科普、健身、游憩等功能均得到相应体现.  相似文献   

基于渐进形态学开运算和偏度平衡法的LiDAR数据滤波方法     

林金彦  邹时林  胡永杰 《安徽农业科学》2015,(16):351-354

基于高程的偏度参数统计的LiDAR数据滤波对地形起伏城区滤波适应性不强的弱点,对该方法进行了改进,提出了结合渐进形态学开运算和偏度平衡法的LiDAR数据滤波方法,该方法的原理就是将所有引起高程的突变转换成全由植被、建筑等非地面点引起,而不是由地形高程引起的,这个转换的中间量就是高差,即将高差作为偏度系数的统计对象.并通过实验验证了该方法的合理性,实验结果表明,改进的方法不仅延续了参数统计法无需阈值的优势,而且对城区滤波更具适应性、合理性和稳定性,能够明显地提高滤波精度.  相似文献   

体育院校大学生参加开放性实验的现状、问题与对策分析 ——以广州体育学院为例     

张甲秀  谭先明  罗冬林 《上海交通大学学报(农业科学版)》2015,(5):114-117

目的：分析探讨开放性实验的现状及存在的问题，旨在提高体育院校开放性实验教学质量，培养综合素质高与专业能力强的有用人才。方法：运用资料分析法对广州体育学院十年来积累的开放性实验教学资料进行研究。结果：（1）开放性实验形成了比较有效的教学模式；（2）历年参加开放性实验的学生人数占当年在校生人数比例非常高；（3）开放性实验科目内容丰富，以验证性实验为主，兼顾综合性和设计性实验；（4）开放性实验教学效果比较满意，教学质量较高。（5）改进开放性实验教学方式、构建独立的实验教学体系等措施可以有效解决体育类大学生参加开放性实验存在的一些问题。结论：体育类大学生参加开放性实验能够有效地巩固所学理论知识，促进专业水平的发展，培养独立分析问题及解决问题的能力。  相似文献   

Fusarium solani Upregulated Sesquiterpene Synthase Expression,Sesquiterpene Production and Allelopathic Activity in Piper betle L.     

Kamrai Woranoot  Rattikarn Buaruang  Kodchakorn Aranyakanon  Kumrop Ratanasut  Anupan Kongbangkerd  Panatda Jannoey  Pranee Nangngam  Chonnanit Choopayak 《水稻科学》2019,26(5):290-299

Activators of sesquiterpene synthase (STS) gene expression and sesquiterpene production in Piper betle L. were examined using quantitative real time PCR and gas chromatography mass spectrometry methods, and the allelopathic activity of untreated and Fusarium solani-treated betel extracts was tested on seed germination and on the shoot and root growth of Thai rice variety PSL2 (Oryza sativa cv. Phitsanulok 2) and three dominant paddy weeds (Eclipta prostrata, Echinochloa crus-galli and Chloris barbata). The results demonstrated that F. solani dramatically upregulated STS expression and productions of β-cubebene, β-caryophyllene and germacrene D sesquiterpene when compared with the untreated control, and that betel extracts had a greater inhibitory effect on weeds than on rice. The effects were more clearly detected on seed germination and root growth than on shoot growth, and they were found to be dose-dependent. It is also noted that F. solani-treated extract had stronger effects than the untreated extract. The species most sensitive to the allelopathic effects was C. barbata, germination of which was completely inhibited even at a dose of 0.1 mg/mL untreated extract. With regards to rice, although betel extract at 1.0 mg/mL showed no inhibition on germination, it affected the elongation of rice roots, in addition to those of the tested weeds. The obtained data suggested that F. solani has potential as an activator of sesquiterpene allelochemical production via STS expression, the latter leading to the treated betel extract having a stronger phytotoxic effect. These results were beneficial in the promotion of natural herbicide production using biotechnology.  相似文献   

干旱矿区不同干扰强度下土壤种子库特征     

冯昶栋  郭小平  罗超  叶金鹏  张昕  马原 《草业科学》2021,38(3):443-452

土壤种子库是矿区植被恢复的重要因素,其特征在一定程度上反映了区域的植被恢复潜力。本研究通过样地调查和室内萌发法对乌海新星煤矿区3种不同干扰条件下的土壤种子库及与其地表植被之间的关系进行分析。结果表明:1)新星矿区土壤种子库共有18种植物,隶属于7科16属,物种生活型以多年生草本植物为主;2)新星矿区土壤种子库平均储量较小(226.51~739.17粒·m^?2),并且随着土层深度增加而呈递减趋势,其90%以上的种子储藏在0?10 cm的表层土壤;3)研究区土壤种子库植物与地上植被的共有物种数少,土壤种子库与地上植被的植物群落相似性较低;4)随着干扰强度的增大,种子库的植被恢复潜力呈现先增大后减少的趋势:道路周边受到中度干扰的自然植被区朝着有利的方向发展,而采矿周边受重度干扰的自然植被区会受到较大负面影响,其多样性以及与其他分区植物群落的相似性较小,种子密度显著降低(P<0.05)。  相似文献   

Design of the Virtual Instrument of Frequency/Amplitude Sweep     

XIE Ting ting  TANG Bao ping  QIN Shu ren 《保鲜与加工》2002,(4):11-14

In this paper the inevitable trend of constructing open ecosystem in modern settlement environment was discussed through the history of the settlement environment and the characters of modern settlement environment.The ecological crisis,change of the modern life and the citizens' needs and the ecological system character show,that it is important for sustainable development of the settlement environment to construct open ecosystem.The construction of modern habitation and the city room embodies the concept of open ecosystem.Then,in construction and research of modern settlement,the ecological viewpoint and method should be applied.  相似文献   

Passage of sediment through flumes and over weirs     

M.G. Bos  J.H.A. Wijbenga 《Irrigation and Drainage Systems》1997,11(1):29-39

This paper reports on laboratory research on the sediment passagecapability through long-throated flumes and broad-crested weirs withwhich the Froude number in the approach channel does not exceed 0.6over a distance of about 20 times the water depth upstream of thestructure. Design rules are given for any combination of flume or weirin combination with any channel.  相似文献   

马蹄形过水断面正常水深计算的遗传算法     

王顺久  侯玉  张欣莉  丁晶 《灌溉排水学报》2002,21(3):43-45

马蹄形过水断面是无压输水隧洞中常采用的断面形式之一 ,因其几何形状复杂 ,水力计算困难。目前常采用的方法有试算法、图解法和迭代法 ,这些方法由于计算量大且精度不易保证 ,不便于在生产实践中应用推广。将马蹄形过水断面正常水深计算转化为非线性优化问题 ,采用实数编码的遗传算法进行求解 ,实例计算表明该方法精度高、通用性强、操作简便 ,便于在生产实践中应用。  相似文献