加速开发宁夏南部山区农业资源

本文分析了宁南山区农业生产条件和存在的问题,认为宁南山区农业资源十分丰富,只要合理开发利用,宁南山区必将成为我区油料、大豆、畜产品的生产基地,并相应地提出了加速开发宁南山区农业资源的措施。     

MOUND FORMATION AT CULVERT OUTLETS1

ABSTRACT One component of the local scour process near a culvert outlet is the formation of an aggraded mound downstream of the scour area. This investigation presents a series of observations and empirical relationships depicting the formation, growth, and estimated maximum dimensions of a mound in a uniformly graded sand material due to clear water scour. The maximum dimensions of the mound were correlated to the discharge intensity (Qg^-0.5 D^-2.5), the maximum dimensions of the scour hole, time, and tailwater elevation. The concept of an approximate area of scour influence was developed relating the mound width, scour hole length, and mound length as a function of the culvert diameter and discharge intensity.     

Impact of a shock wave on a structure on explosion at altitude

The number of explosive attacks on civilian buildings has recently increased and the pattern of damage inflicted on structures when an explosion takes place at altitude remains quite difficult to predict. The primary aim of the work reported here was to enhance the understanding of how blast waves from an explosion at altitude interact with the ground and with a structure. Small-scale experiments were conducted using a propane–oxygen stoichiometric mixture as explosive. This approach is original because it models high-explosive detonation in terms of gaseous charge explosion using TNT equivalents. Several non-dimensional laws are expressed and validated by experiments. These relationships allow determination of the propagation of a blast wave and its interaction with a structure as a function of the position of the explosive charge when the explosion occurs at altitude. Then, from knowledge of the blast loading, using Hopkinson's scaling law and TNT equivalents, we can predict the interaction of blast waves with the ground and a structure on a real scale. Simulations were performed using the Autodyn code, and good correlation with the experimental results was obtained.     

镇江旅游资源特色及其开发刍议

镇江旅游资源具有“江山风光”、“城市山林”、“佛道文化”、“名人故迹”等特色。分析了镇江旅游开发具有的优势条件,包括水陆交通枢纽、名优特产丰富、局部区位优势等方面,在此基础上提出若干政策建议,包括开辟长江水上游和沿江风光带、发展宗教朝觐游、建设古代科技博物馆、开拓宁镇扬度假市场、精心组织旅游线路等,以促进镇江旅游业的进一步开发,提高它在苏南旅游区中的地位。     

包头市达茂旗土地退化现状及其成因分析

通过对包头市达茂旗自然环境和社会经济状况的研究，得出其土地退化问题十分严重。主要表现为：风蚀沙化严重、土壤水蚀问题突出、草地退化趋势加剧、耕地肥力下降相当普遍、盐渍化问题不容忽视。针对土地可持续利用中存在的主要制约因素进行了深入分析，得出长期的自然和人为因素的综合干扰是导致土地退化的主要原因，以期为各级决策部门提供参考。     

工程复杂系统灾害形成与自愈防范原理研究

工程安全科学是涵盖机电工程、过程工程、信息论、系统论、控制论、耗散结构理论、医学、人文科学、社会科学的一门新兴科学。工程安全科学应该而且必将列入我国基础学科发展的行列。笔者探讨了工程安全科学的定义,重点研究工程活动中人-机-过程-环境复杂系统故障、事故发生发展及其防治、根除的规律,研究危险源隐患转化为危害或灾害的条件和影响因素及其监测、预防和控制。提出并讨论了工程系统灾害形成的机理,工程复杂系统灾害形成遵循的共性规律,工程复杂系统故障和事故的诊断预测以及灾害的防治原理。安全度既取决于危险又取决于控制能力。与故障作斗争是与疾病作斗争以另一种方式的延续。借鉴医学的“自主调理是治疗学的第一原理”和系统科学的自组织理论,提出并研究了故障自愈原理及安全的动态评价与灾害的自愈防范机制。该研究的理论和成果是落实科学发展观、促进人-机和谐和实现安全、绿色、节约型流程制造的重要途径。     

"两硬"条件高瓦斯放顶煤工作面瓦斯防治技术探讨

放顶煤综采工作面由于其工艺的特殊性,瓦斯防治工作一直是安全开采的难题之一,大同矿区特有的“两硬”条件（坚硬顶板、坚硬煤层）作开采时其顶板、顶煤难以冒落,给瓦斯治理带来了更多的困难.经过近几年的攻关研究,同煤集团已经形成了一整套行之有效的方法,保证了矿井的安全生产.本文对“两硬”条件下的高瓦斯放顶煤工作面的瓦斯防治方法做一简单的介绍.     

Test of a Model to Assess the Condition of Lodgepole Pine Stands

/ A predictive model for assessing stand condition as a function of suitability for achieving specified management objectives was originally developed using a data set for only 28 stands. In this study, we evaluate the model using an operational-sized data set composed of currently collected stand inventory data for 238 stands in the Snowy Range of the Medicine Bow National Forest in southern Wyoming. We compared its predictions of old growth suitability to results of a separate special old growth survey. Stands were characterized as profiles of variables derived from stand inventory data, and plotted as points in two-dimensional space where similarity between stands was reflected by the distance between their points. Results suggest the model is useful for classifying stand condition using relatively large sets of data currently collected during routine stand inventories.     

东营凹陷北带沙四下凝析油气成藏模式与主控因素

本文在已经确立了东营北带沙四下亚段凝析油气藏烃源岩的基础上,通过结合热演化史、古地温史,分析储层流体包裹体的均一温度,确定该区沙四下凝析油气藏存在三个成藏期次,分别为沙三~沙二沉积时期的古油藏形成初期、沙一段沉积末期至馆陶组沉积时期的古油藏形成期、明化镇组沉积时期至今的古油藏裂解及凝析气藏形成期。结合构造发育史建立了沙四下亚段凝析油气藏成藏模式;并分析了本区成藏主控因素。     

好氧颗粒污泥的影响因素及其形成机理探讨

结合国内外的研究成果,对好氧颗粒污泥的影响因素及形成机理进行了探讨,认为接种污泥、进水基质和有机负荷、运行方式、水力剪切力、沉淀时间等对好氧颗粒污泥的培养具有重大影响,是好氧颗粒污泥形成的主要影响因素;并提出了好氧颗粒污泥形成机理的"凝结核猜想",认为好氧颗粒污泥的最终形成分为出现凝结核、形成胚胎颗粒污泥及形成好氧颗粒污泥三个阶级。