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Search Results: 1 - 10 of 83422 matches for " 尹红健 "
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不同预制体结构炭/炭复合材料烧蚀性能
,,熊翔,黄伯云
复合材料学报 , 2007,
Abstract: 采用电弧驻点烧蚀实验方法,测试了分别以细编穿刺毡和针刺无纬布整体毡为增强体的2种C/C复合材料的烧蚀率,并用电子扫描显微镜观察了烧蚀表面形貌。结果表明:C/C复合材料的烧蚀由化学烧蚀和机械剥蚀共同控制,以机械剥蚀为主;细编穿刺毡结构C/C复合材料由于Z向纤维束的存在,加速了材料烧蚀表面粗糙度的变化,烧蚀率略高于针刺无纬布整体毡结构C/C复合材料;针刺无纬布整体毡结构C/C复合材料中无纬布层与烧蚀气流垂直,具有良好的烧蚀性能。
热解炭结构对c/c复合材料烧蚀性能的影响
 ,波 ,熊翔 ,黄伯云
材料研究学报 , 2007,
Abstract: ?采用电弧驻点烧蚀试验方法测试了具有典型光滑层和粗糙层热解炭结构的两种c/c复合材料的烧蚀率,研究了热解炭结构对c/c复合材料烧蚀性能的影响.结果表明:热解炭结构对c/c复合材料烧蚀性能有较大的影响.具有粗糙层结构的c/c复合材料石墨化度高,不同炭结构之间结合好,线烧蚀率和质量烧蚀率较小,烧蚀性能较好;具有光滑层结构的c/c复合材料石墨化度低,烧蚀性能较差.
Semi-supervised learning based on K-means clustering algorithm
基于半监督学习的K-均值聚类算法研究

LIU Tao,YIN Hong-jian,
刘涛
,

计算机应用研究 , 2010,
Abstract: This paper constructed a new classified function which mixed Euclidean distance with supervising information. Taking into account that K-means algorithm was sensitive to the initial center, used search space of particle swarm algorithm was used to simulate the clustering Euclidean space to find a better cluster center of clustering. At the same time, brought up a strategy of species dynamic management to improve the efficiency of particle swarm optimization search. The algorithm got a good clustering accuracy on a number of UCI testing data sets.
热处理温度对添加碳化硼炭/炭复合材料摩擦磨损性能的影响
,辛伟,左劲旅,,李江鸿
摩擦学学报 , 2008,
Abstract: 以添加碳化硼的炭纤维针刺整体毡为预制体,经化学气相渗透以及树脂浸渍/炭化混合增密制备含碳化硼C/C复合材料,通过MM-1000型摩擦磨损试验机并结合摩擦表面和磨屑形貌的扫描电子显微镜观察分析,研究了热处理温度(2000℃、2300℃和2500℃)对含碳化硼C/C复合材料摩擦磨损性能的影响.结果表明:在2000℃时,含碳化硼C/C复合材料呈现出磨粒磨损特征,其磨损相当严重,摩擦系数较高,摩擦力拒曲线翘尾严重;在2300℃时,碳化硼发挥了促进石墨化的作用,使得含碳化硼C/C复合材料的石墨化度提高,在摩擦过程中摩擦表面能够形成平整而光滑的自润滑膜,材料耐磨能力明显增强,摩擦系数略有下降,制动过程平稳;在2500℃时,含碳化硼C/C复合材料的石墨化度提高至97.8%,与2300℃时相比,其摩擦系数和磨损量具有一定程度的增加,摩擦力矩曲线抖动加剧.
绿色荧光蛋白标记检测枯草芽孢杆菌在水体中的存活动态
敬芳,周向阳,,李永,侯红利,张文华
分析化学 , 2007,
Abstract: 基于生物-化学协同控制植物病害的原理,构建了一种由枯草芽孢杆菌和烯酰吗啉组成的对辣椒等作物疫病具有较好的防治效果的菌药合剂(DMBS).按照农药降解研究基本规则,采用绿色荧光蛋白(greenfluorescentprotein,GFP)标记技术和细菌学研究方法研究了DMBS在去离子水、地下水、自来水、河水和雨水中的降解动态.结果表明,GFP标记可以用于枯草芽孢杆菌在5种水环境中的存活检测.在(25±1)℃条件下,枯草芽孢杆菌菌剂和DMBS中的枯草芽孢杆菌数量主要表现为前12d迅速下降,此后则随时间的延长在一定的范围内呈变动的上升或下降趋势.在(50±1)℃灭菌和不灭菌的条件下,均表现为前12d迅速下降,12d后趋于稳定或缓慢下降.枯草芽孢杆菌在5种水中的降解速度较慢,在(25±1)℃和(50±1)℃条件下存放86d后,其含量均在104cfu/mL以上.培养温度和灭菌条件对枯草芽孢杆菌在不同水体中存活动态有一定的影响,菌药合剂中的烯酰吗啉对该菌的存活则没有显著影响.
液态地膜覆盖对土壤水分有效性的影响
光华**,郝亮,赵永,,刘作新
生态学杂志 , 2013,
Abstract: ?采用田间微区试验方式,观测和分析了液膜地表覆盖下土壤含水量、花生植株伸长速率、叶面积指数、叶片光合速率、水分利用效率及产量等指标,并利用隶属函数法进行数值转换后,对液膜覆盖的土壤水分有效性进行了分析。结果表明,液膜覆盖提高土壤含水量103%~167%,且随液膜浓度的增大有效性提高;不同土层间,花生耗水量差异显著,其中以土层深度为20~40cm差异最大;液膜覆盖也明显提高了光合速率,增幅为1.9%~15.6%;叶面积指数提高0.3%~26.4%,改善了植株光合形态。综合全部指标表明,液膜类型为3号,液膜浓度为高水平时,覆盖效应最为明显。?
利用傅立叶变换研究铜双晶纳米线的断裂行为
,王奋英,蒋璐芸,,刘云
物理化学学报 , 2009,
Abstract: 利用超大规模分子动力学模拟程序研究了[111]||[110]双晶铜纳米线的拉伸断裂行为.针对样品的周期性结构,开发了离散傅立叶变换进行晶体特征分析的技术.通过转换实空间的原子密度分布函数,得到振幅-频率图和归一化的长轴原子密度分布图.这两种处理方法提供了晶体取向和结晶状态的信息,其中振幅-频率图适合描述大范围的晶体特征,而归一化长轴的原子密度分布则反映了局部的细节.利用该方法,考察了不同拉伸时刻[111]||[110]双晶铜材料的晶体取向和结晶状态.在拉伸过程中,从振幅-频率图可以观察到4.78nm-1处的[111]特征峰和7.81nm-1处的[110]特征峰发生了低频移动和峰形变宽的现象;同时在断裂时刻观察到了5.50nm-1处的[100]特征峰.证明[111]||[110]铜双晶纳米线在拉伸形变过程中发生了界面融合,同时界面层原子向[100]晶向的转变,最终导致了双晶纳米线在[111]晶向一侧断裂.傅立叶变换晶体分析技术在纳米材料和器件的研究中可以发挥积极的作用.
热处理对炭/炭-铜复合材料载流磨损行为的影响
杨鹏翱,,,杨双磊
- , 2015, DOI: 10.11951/j.issn.1005-0299.20150507
Abstract: 为探明炭/炭(C/C)多孔体热处理对炭/炭-铜(C/C-Cu)复合材料载流磨损行为的影响,采用化学气相渗透法(CVI)增密的C/C多孔体,再通过压力熔渗法制备C/C-Cu复合材料.采用载流动态磨损试验机测试C/C-Cu复合材料载流磨损行为,利用数字式三维视频显微镜和扫描电子显微镜观察复合材料磨损前后的表面形貌,研究了C/C多孔体经过2 000 ℃热处理对C/C-Cu复合材料载流磨损行为的影响.结果表明:C/C-Cu复合材料的质量磨损率和线磨损率比C/C多孔体未经热处理的复合材料分别降低了34.42%和17.84%;C/C多孔体经过2 000 ℃热处理,石墨化度提高,片层劈裂阻力减小,在载荷的作用下石墨片层易于劈裂形成细小的石墨微晶碎片,迅速填充修复表面缺陷,形成具有一定润滑作用、平整的摩擦膜,有效抑制了局部非均匀磨损的扩大,减弱了磨粒磨损和电弧放电引起的烧蚀、粘着、氧化磨损之间的循环交替磨损,载流磨损性能提高.
To explore the effects of heat treatment of Carbon/Carbon (C/C) substrates on wear behavior of Carbon/Carbon-Copper (C/C-Cu) composites, copper-impregnated carbon fiber reinforced carbon composites were fabricated by infiltrating molten copper alloy into C/C substrates, which were made by chemical vapor infiltration (CVI). The wear behavior of C/C-Cu composites was investigated by using a dynamic wear test apparatus during application of an AC electrical current. The worn surfaces of composites before and after test were observed by 3D microscope and SEM. Effects of 2 000℃ heat treatment of C/C substrates on wear behavior of C/C-Cu composites were investigated. The results indicate that the mass wear rate and linear wear rate of the C/C-Cu composites whose C/C substrates were treated at 2 000 ℃ were 34.42% and 17.84%, respectively, lower than that of composites without heat treatment. The graphitization degree of C/C substrates improved after 2 000 ℃ heat treatment, thus, the interlaminar splitting resistance was reduced.Thus it is easier for graphite sheets to split into small graphite scraps and form a smooth and lubricant film on the surface, which restrained the inhomogeneous wear induced by surface defects. Therefore, the mutual effects of abrasive wear, adhesive wear, oxidation wear and arc ablation are weakened.
降低反-2-壬烯醛及老化前驱体的酿造工艺研究
黄淑霞,余俊,,,董建军
- , 2017, DOI: 10.3969/j.issn.1673-1689.2017.08.007
Abstract: 为降低麦汁和啤酒中反-2-壬烯醛与老化前驱体壬烯醛潜力的含量,研究糖化过程中影响麦芽脂肪氧合酶(LOX)作用的关键因素(蛋白休止温度、醪液pH值、麦芽粉碎度、麦芽LOX活力),确定最佳工艺:蛋白休止温度为55~60 ℃、醪液pH为5.5、EBC粉碎机磨盘间距为0.5 mm、LOX活力越低越好。大生产验证试验显示:蛋白质休止温度为55 ℃、使用低LOX麦芽时,啤酒中反-2-壬烯醛、壬烯醛潜力降低幅度分别为6.7%~25.0%、9.2%~20.3%,啤酒新鲜度得分提高4.2%~16.1%。
The key factors influencing malt lipoxygenase(LOX) during saccharification period were studied,such as protein rest temperature,pH value,grinding degree,LOX activity of malt for reducing the content of trans-2-nonenal and aging precursor nonenal potential of wort and beer. The optimum process parameters were confirmed:protein rest temperature was 55~60 ℃,mash pH was 5.5,EBC grinder distance was 0.5 mm,LOX activity was as low as possible. Experimental results of large-scale production showed that when protein rest temperature was 55 ℃,and malt with lower LOX activity was used,the content of trans-2-nonenal and nonenal potential declined 6.7%~25.0% and 9.2%~20.3% respectively. Beer freshness score increased 4.2%~16.1%
四种网蝽科昆虫外部形态特征提取与分析
Extraction and Analysis of External Morphological Characteristics from Four Species of Lace Bugs (Hemiptera:Tingidae)

潘鹏亮,,张方梅,智亚楠,
- , 2017,
Abstract: 中文摘要:随着计算机图像处理技术的发展,昆虫图像特征提取技术在昆虫分类学中的应用越来越广泛。相关的研究报道涉及到多种较大型昆虫和节肢动物,但对身体较小昆虫的外部形态特征提取与分析,及其雌雄鉴别方面的报道不多。本研究利用中国农业大学IPMist实验室开发的BugShape 1.0对体型较小的4种网蝽科Tingidae昆虫成虫进行了外部形态特征的提取,分析了所得参数在其种类和雌雄方面的差异。结果表明,获得的10个参数在4种网蝽成虫中差异均有高度统计学意义。4种网蝽雌雄成虫在面积、等效圆半径、偏心率、球状性和圆形度5个参数方面的差异有高度统计学意义,初步认为可以作为区别这4种网蝽雌雄成虫的重要指标。判别分析证明,4种网蝽交叉判别的正确率高达98.5%,对种类和性别同时进行判别时,交叉判别的正确率为85.0%。利用重心法得到的聚类分析结果符合传统昆虫分类学的结果,同一属的菊方翅网蝽 Corythucha marmorata和悬铃木方翅网蝽 C.ciliata优先聚为一类,其他2种网蝽先后分别聚类。本研究利用图像处理与分析技术得到的参数适合对此类昆虫进行种类和性别的鉴定,初步表明该技术在此类害虫分类鉴定中的科学性和可行性。
英文摘要:Along with the development of computer image processing techniques, the feature extraction of insect images was applied widely in the insect taxonomy. Although the published studies had reported the application of related techniques that on some relative large-sized insects and other arthropod species, little was conducted to analyze the external morphological features of small-sized insects and different gender samples. In this study, the external morphological parameters of4 lace bug species were extracted using BugShape (ver. 1.0) developed by IPMist Lab at the China Agricultural University, and then the morphological differences of inter-species and between male and female adults were analyzed. The result showed that 10 morphological parameters were significantly different among the 4 adult species. Five parameters (area, equivalent radius, eccentricity, sphericity and circularity) were considered as vital indicators for distinguishing the male and female adults in one species with highly significant difference. The result of canonical discriminant analysis indicated that the correct rate of cross-validation was 98.5% when only using species as the treatment, and was 85.0% when using species and genders as the treatments. Two lace bug species ( Corythucha ciliata and C. marmorata) which belong to one genus ( Corythucha) were clustered in the same group, and the others ( Stephanitis nashi and Perissonemia borneenis) were clustered successively by the hierarchy cluster with the centroid method. The hierarchy cluster result was coincident with that of the traditional insect taxonomy. In conclusion, our study indicated that the basic method of feature measuring and extraction of shape features was very descriptive to the species and genders of these adult bugs, and thus demonstrated the scientificity and feasibility of this method to the classification and determination of these bugs. 2017,36(5): 531-539 收稿日期:2017-04-03 DOI:10.11984/j.issn.1000-7083.20170107 分类号:S431.9;S126 基金项目:信阳农林学院校内青年教师基金项目(201401015) 作者简介:
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