圆口径天线远场分析

采用基尔霍夫公式,并利用计算机编程技术实现了对圆口径天线的远场（电场）的精确计算,同时得到天线的方向图,分析了其辐射特性,并将程序的计算结果与相关文献中的理论值作对比,验证了该方法的准确性及有效性。     

中美油罐VOCs排放核算公式参数敏感性研究

介绍了中石化系统VOCs排放核算公式和美国环保署推荐公式,并对2种方法的优缺点进行了对比分析.结合油罐排放核算实例,分析了导致中美两种方法计算结果不同的原因,最终确定了VOCs年排放量核算结果为43.43t.利用了回归分析的方法,对中美核算公式的主要参数进行了敏感性研究,各参数拟合方程的R²均接近于1,将t统计量P值显著性水平设置为0.05,结果表明,在计算浮顶罐VOCs排放时,中石化公式的敏感参数包括：粘附系数、风速、二次密封系数、密封系数和风速指数;EPA公式的敏感参数为内壁粘附系数、风速、静风边缘密封排放系数、有风情况下边缘密封排放系数和浮顶板密封长度系数,风速指数为非敏感参数.     

灾民撤退网络流模型及其GIS模拟技术

灾民撤退问题实质上是一个多源点、多收点的网络流问题。本文建立了用于灾民撤退的网络流分析模型,介绍了基于地理信息系统网络分析的灾民撤退模拟技术。通过对某蓄洪区的实例分析表明,网络分析是模拟灾民撤退的有效方法,地理信息系统技术是辅助制定灾民撤退方案的崭新途径。     

形率法测算单株立木材积公式选用

单株立木求积,是林业科研和生产的重要内容.本文通过对临武县杉木人工林分590株标准木进行测算研究,发现不同的立木求积式其求积精度有明显差异,由此优选出精度高简便实用的测算公式.     

铁路隧道火灾中烟气逆流层长度的研究

以狮子洋隧道为工程背景,对不同火源热释放速率、不同通风风速、不同坡度及不同断面当量直径情况下的火灾进行了数值模拟。分析了隧道烟气逆流层长度的变化规律,并对模拟数据进行了拟合。结果表明,隧道烟气逆流层长度与通风风速、火源热释放速率、隧道断面当量直径的自然对数值拟合均符合直线关系,呈递增或递减变化;坡度对烟气逆流层长度的影响随通风风速的增大而减弱。在分析烟气逆流层长度变化规律的基础上,建立了烟气逆流层长度与火源热释放速率、通风风速及断面当量直径的关系式,通过对数据拟合获得了烟气逆流层长度公式,该公式推导合理,并有所创新。     

两种计算扩散参数方案的对比研究

利用由泰勒公式导出的Hay-Pasquill方法和Draxler经验公式方法,处理了双向风标风速仪的观测资料,计算并分析了兰州郊区皋兰县的扩散参数.结果表明,Hay-Pasquill方法的计算结果较Draxler经验公式方法稍大,皋兰地区的扩散参数比Briggs开阔平原地区的扩散曲线高2～3个稳定度级。      

三相生物流化床膨胀特性方程的研究

研究建立了描写三相生物流化床床层膨胀特性的经验关联式．当已知床内表观液速、表观气速和载体上生物膜厚度时,能比较准确地预测床层膨胀高度,为设计提供依据．与以往不同的是,本研究通过等效函数的设置和求解,用一个方程将两相床和三相床的膨胀特性描述出来．该方程能反映三相床低气速下的床层收缩行为,在气速为零时可还原为两相床．试验用反应器直径１．４ｍ,高６．５ｍ,载体为０．３—０．５ｍｍ的石英砂,射流曝气体内充氧．４种生物膜厚：５２,８０,１１５,１３７μｍ．试验用生活污水ＢＯＤ５４７．６—７７．２ｍｇ／Ｌ．     

Fertilizer application training programs,the adoption of formula fertilization techniques and agricultural productivity: Evidence from 691 apple growers in China

The article examines whether agricultural training boosted technology adoption and productivity was a key issue that was concerned by policymakers and researchers. Thus, impacts of fertilizer application training programs on the adoption of formula fertilization techniques and agricultural productivity were analyzed by using the survey data of 691 apple growers. The results indicated that: (i) compared with farmers who did not participate in fertilizer application training programs, the probability of the adoption of formula fertilization techniques was significantly increased by 256.1% for farmers who participated in fertilizer application training programs; (ii) fertilizer application training programs boosted the adoption of formula fertilization techniques via influencing farmers' cognition and willingness; (iii) yield was significantly increased by 14.3% at the 5% level through participating in fertilizer application training programs, and fertilizer application training programs improved agricultural productivity by means of enhancing the adoption of formula fertilization techniques. This study was conducive to evaluating the effectiveness of agricultural training and boosting agricultural sustainable development.     

模型公式法在确定BOD_5样品稀释系数中的应用

本文提出了一种利用以往监测数据计算ＢＯＤ５稀释系数的简易公式,为ＢＯＤ５测定中稀释系数的确定提供了一种科学准确的计算方法。本法不受经验因素的限制,并能确保ＢＯＤ５样品分析的可靠性与成功率,具有应用与推广价值。     

Experimental investigation on the lower flammability limits of diethyl ether/ n-pentane/epoxypropane-air mixtures

Diethyl ether (DEE), epoxypropane (PO) and n-pentane have excellent ignition and combustion performance; hence, they have a wide variety of applications in industry and advanced aviation propulsion systems. As these fuels are flammable at normal temperature and pressure, their explosive characteristics need to be explored. In this study, the lower flammability limits (LFLs) of vapor mixtures of DEE/PO/n-pentane in air were measured in 20 L, closed, stainless steel spherical vessels. Experimental results were obtained at ambient atmospheric pressure and an initial temperature of 40 °C. The experimental results show that the LFLs of DEE-air, n-pentane -air, and PO-air are 1.81 vol%, 1.41 vol% and 2.44 vol%, respectively. The LFLs of binary/ternary fuel mixtures under different compositions were tested, and the experimental results are compared with the classical Le Chatelier's formula. The results show that, for the binary fuels (i.e., DEE/PO, DEE/n-pentane, PO/n-pentane)-air mixtures, the maximum difference of the LFLs between Le Chatelier's formula and the experimental results is 6.10%. For the ternary fuels (i.e., DEE/PO/n-pentane)-air mixtures, the maximum difference of the LFLs between the two results is 6.33%. Due to the adiabatic flame temperature of each single fuel mixture being close, the Le Chatelier's formula is applicable for an estimation of the LFL for DEE/PO/n-pentane-air mixtures.