Basic handling characteristics of wood fuels: Angle of repose,friction against surfaces and tendency to bridge for different assortments     

《Scandinavian Journal of Forest Research》2012,27(1-4):583-597

Basic handling characteristics were measured for sawdust, fuel pellets, fuel chips, hog fuel and chunkwood. The aim was to find relations between the basic handling characteristics and easily measurable fuel properties to facilitate the design of feeding systems in heating plants. The angle of repose was 25–55° and increased with the increasing ratio of particle length to thickness and with the increasing content of hooked or long particles. The angle of static friction, 10–40°, was affected more by the kind of surface than the fuel and followed the ascending order: coated plywood, urethane rubber, particle board, stainless steel, concrete and rubber belt conveyor. The tendency to bridge varied considerably and increased with greater content of hooked or long particles, a deeper fuel bed depth over the opening and a higher moisture content. The results indicate that more attention should be paid to the particle shape.  相似文献   

热带作物田间废弃物多功能粉碎综合实验装置研究     

张世亮  李德荣  陆兵  张建  李明  薛忠 《热带作物学报》2013,33(12):79-83

介绍热带作物田间废弃物多功能粉碎综合实验装置的组成及其工作原理，详细论述该实验装置小车行走与控制，刀辊组件转速、直径、刀片、刀辊长度等的调节，粉碎工作室形状调节，实验数据自动采集与信息化处理等设计问题。该装置对于系统开展热带作物田间废弃物粉碎设备的基础实验研究具有重要意义。  相似文献   

木材表面非极性化原理的研究 Ⅱ.木材与苯乙烯接枝共聚过程中化学官能团和表面极性的变化   总被引：2，自引：0，他引：2  

阎昊鹏  秦特夫 《木材工业》1999,(6)

通过对杉木、杨木木材及其主要成分在与苯乙烯接枝共聚反应过程中化学官能团及临界表面张力变化的研究,探讨了木材各化学组成在接枝共聚过程中的反应性能和对木材表面极性的影响。研究表明:木材可与苯乙烯发生接枝共聚反应,反应只在木素和苯乙烯之间进行。木材与苯乙烯接枝共聚可降低木材临界表面张力,即降低木材表面自由能,从而有效地改善木材的极性。  相似文献   

Morphological Basis of Resistance in Cotton to the WhiteflyBemisia Tabaci     

N. S. Butter  B. K. Vir 《Phytoparasitica》1989,17(4):251-261

The morphological basis of resistance to the whiteflyBemisia tabaci Genn. (Aleyrodidae: Hemiptera) was studied. The plant characters examined were leaf area, thickness of leaf lamina, hair density, hair length, angle of insertion of leaf hair, and density of gossypol glands. Hair density and leaf thickness were positively correlated with the population ofB. tabaci, and a positive correlation was obtained between the adult whitefly population and gossypol glands on stem internodes. Cotton genotype USA-22 (sparsely hairy) was found to be more tolerant toB. tabaci than was genotype USA-13 (velvety hairy). The use of thinner and glabrous leaved cotton varieties is suggested to minimize the whitefly menace in cotton.  相似文献   

Identification of ocular matrix metalloproteinases present within the aqueous humor and iridocorneal drainage angle tissue of normal and glaucomatous canine eyes   总被引：1，自引：0，他引：1  

William L. Weinstein  Ursula M. Dietrich  John S. Sapienza§  K. Paige Carmichael†  Phillip A. Moore  Thomas M. Krunkosky‡ 《Veterinary ophthalmology》2007,10(S1):108-116

  相似文献   

大型烟囱垂直度偏差的测量方法     

廖勇元  吴善能 《技术与市场》2010,(2):10-11

大型烟囱一般是工业厂区的高耸建筑，经过几十年的使用，需要重新鉴定其结构可靠性，烟囱的垂直度，是一个很重要的安全指标。由于烟囱为圆形截面，不能直接测量，而且工业厂区内建筑较多，通视条件较差，给测量带来很多困难。通过测量烟囱上下两个标高处的外轮廓水平角度，换算出上下标高处的相对水平偏移角，再用角度交汇方法求出最终偏移值，经过精度分析，完全满足工程精度要求。本文以上海某大型烟囱为例，提出了对已有烟囱垂直度偏差的检测方法，以用于大型服役烟囱的监测。  相似文献   

乳粉喷流性及影响因素的探讨     

石春权  孙克杰  刘玲  于自强 《乳业科学与技术》2007,29(5):239-243

通过对乳粉颗粒观察及对其喷流性的研究,测定代表流动性的自然坡度角（θr）、压缩率（Cp）、凝集度（Ch）、代表喷流性的崩溃角（θf）、差角（θd）、分散度（Ds）,讨论各种性能对乳粉的影响因素.  相似文献   

Mapping Ridolfia segetum patches in sunflower crop using remote sensing     

J M PEÑA-BARRAGÁN  F LÓPEZ-GRANADOS  M JURADO-EXPÓSITO  & L GARCÍA-TORRES 《Weed Research》2007,47(2):164-172

Ridolfia segetum is a frequent umbelliferous weed in sunflower crops in the Mediterranean basin. Field and remote sensing research was conducted in 2003 and 2004 over two naturally infested fields to determine the potential of multispectral imagery for discrimination and mapping of R. segetum patches in sunflower crops. The efficiency of the four wavebands blue (B), green (G), red (R) and near‐infrared (NIR), selected vegetation indices and the spectral angle mapper (SAM) classification method were studied using aerial photographs taken in the late vegetative (mid‐May), flowering (mid‐June) and senescence (mid‐July) crop growth stages. Discrimination efficiency of R. segetum patches in sunflower crops is consistently affected by their phenological stages, in this order: flowering > senescence > vegetative. In both fields, R. segetum patches were efficiently discriminated in mid‐June, corresponding to the flowering phase, by using the waveband G, the ratio R/B or SAM with overall accuracies ranging from 85% to 98%. The application of the median‐filtering algorithm to any of the classified images improved the accuracy. Our results suggest that mapping R. segetum weed patches in sunflower to implement site‐specific weed management techniques is feasible with aerial photography when images are taken from 8 to 10 weeks before harvesting.  相似文献   

旋转编码器在回转体回转角度测量中的应用   总被引：4，自引：0，他引：4  

于晓东  胡大欣 《林业机械与木工设备》2005,33(2):43-44

针对回转体回转角度测量的实际情况，研制了新型回转体回转角度测量仪。该测量仪是以光、机、电为一体的旋转编码器作为传感器，测量回转体的回转角度。这种测量输出的信号为数字信号，克服了零漂、测量准确度低等缺点，提高了测量的准确度和可靠性。  相似文献   

竹材表面润湿性研究   总被引：12，自引：0，他引：12  

江泽慧  于文吉  余养伦 《竹子研究汇刊》2005,24(4):31-38

从竹材表面润湿性的原理推导入手,采用测定竹材表面接触角的方法,对竹材表面的自由能、路易丝-范得华力和酸碱力关系进行研究,并分析不同部位和不同处理方法对竹材表面湿润性的影响.结果表明:表面粗糙度,抽提物的含量和分布是影响竹材表面润湿性的主要原因;竹材的表面自由能是以路易丝-范得华力为主体;竹材表面的自由能差异主要由竹材表面的酸碱力引起;竹材表面具有稳定的路易丝-范得华力,其数值大小不受竹材表面的化学成分的影响.  相似文献