The new era of the livestock production in Mongolia: Consequences on streams of the Great Lakes Depression

Mongolia, a landlocked country of the Central Asian plateau, is experiencing a significant modification of herding practices coupled with an increase in livestock numbers. These modifications lead to increasing impacts of grazing on the Mongolian steppes with major consequences on the waterbodies. We researched the impacts of grazing intensity on the streams of the Great Lakes Depression in northwestern Mongolia. We assessed the level of watershed and stream bank erosion and the type of vegetation structure. We calculated the livestock densities per watershed and linked them to the stream water discharge through a new metric (I_CU). I_CU was created as a function of cattle unit density and water discharge, having water discharge at a stream section reflecting its location in the drainage and therefore accounting for the surface area drained upstream. We measured also the major nutrients in the stream water and researched the causalities between the grazing and the impairment of watersheds and streams. Our results suggest that the increase of livestock numbers is reaching beyond the grassland and affecting the stream ecosystem. Two major impacts were highlighted by this study, 1) the extensive watershed and stream bank erosion and 2) the increase in concentration of suspended particles and orthophosphate in stream systems. When compared with past values from literature, our results show recent eutrophication of the streams compared to the pre-liberalization of the herding activity in Mongolia (before 1991). Consequently the continued uncontrolled increase of livestock numbers could threaten the conservation of the Mongolian waterbodies, with notable consequences on the life of the nomadic population of the Central Asian Plateau.     

中欧绿道——设计可持续发展的国际性廊道

以绿道运动在中欧的发展与实际应用为背景,首先回顾了绿道运动最初在欧洲的起源与早期的发展,其次介绍了执行这一运动的可持续发展环境合作组织的愿景、任务及绿道运动在中欧与东欧背景下开展的特点、目标与对象、方法及所产生的有效成果,最后对绿道运动未来的发展方向做了展望.     

一种湿式安全型中央制动器

制动器是工程车辆的关键部件,对车辆运行的安全起着决定性作用.不同功用的制动器,其结构也不相同,介绍一种适用于恶劣环境,特别是可在煤矿井下高瓦斯环境中使用的,具有隔爆性能的湿式安全型中央制动器,对其结构特点、工作原理和制动力矩特性进行分析,为设计同类型制动器提供参考,也为使用和维护这种制动器提供理论依据.     

国产首套刨煤机组控制系统在晓明矿的应用

文章介绍了由三一重型装备有限公司自主生产的全自动刨煤机BH38/2×400的控制系统,该控制系统的硬件系统由防爆工控机、主控制器、支架控制器等设备组成,其通信系统采用可靠性高,传输距离远的CAN总线通信方式.通过全自动刨煤机组BH38/2×400在铁法晓明矿北二419工作面的应用,标志着我国已经取得了薄煤层开采的关键核...     

中央空调自动控制系统概述

介绍了中央空调自动控制系统的组成、内容、功能、特点和分类,着重介绍了几种常用的中央空调自动控制方法。     

Automatic rotational symmetry determination for shape analysis

The determination of the rotational symmetry of a shape is useful for object recognition and shape analysis in computer vision applications. In this paper, a simple, but effective, algorithm to analyse the rotational symmetry of a given closed-curve shape S is proposed. A circle C with the centroid of S as the circle center and the average radius of S as the circle radius is superimposed on S, resulting in the intersection of C and S at a set of points. By theoretical analysis, the relationship between the order N_s of the rotational symmetry of S and the number of intersection points between C and S is established. All the possible values for N_s are determined. And finally N_s is determined by evaluating the similarity between S and its rotated versions. In the proposed algorithm, only simple pixel operations and second-order moment function computation are involved. Several problems caused by the use of discrete image coordinates are analysed and solved for correct decision-making in the algorithm. Good experimental results are also included.     

大型楼宇空调自动控制系统模型选用与系统设计

本文着重从空调自动控制系统模型的选用,系统的设计以及系统的可靠性这三方面介绍空调自动控制系统的设计。     

石化装置中联合控制室的建筑设计评析

通过对3套石化装置联合控制室建筑设计的分析研究,阐述了当前潮流趋势装置管控一体化-联合控制室的优点及其共同拥有的建筑设计特点,特别强调抗爆结构的联合控制室与常规非抗爆建筑物的建筑设计的主要区别。     

扇聚焦等时性回旋加速器性能的改进和提高

安装了ＥＣＲ离子源及其外注入系统后，增加了离子种类、提高了束流强度。扇聚焦等时性回旋加速器（ＳＦＣ）主要工作点分布于三次谐波加速区域，为了匹配外注入系统，仔细地研究了中心区，重新设计加工了Ｄ盒及假Ｄ。为了改进ＳＦＣ性能，提高运行效率，同时进行了其它改进工作。介绍了改进后的ＳＦＣ的调束工作。     

川西地区中部存在泥盆系—石炭系吗？——一个不整合面的地质属性推论

四川盆地川西坳陷泥盆系具有发育大型油气藏的成藏条件，但由于泥盆系埋藏深度大、研究程度低，其分布状况长期存疑。近期，在川西坳陷中部二叠系底与寒武系底之间新发现了一个角度不整合面，因资料限制，不能直接确认该不整合面的地质属性。为此，以该角度不整合面为研究对象，依据地表露头、钻井、区域构造演化、川西坳陷北部泥盆系—石炭系残余地层分布以及沉积相等资料，分析推断该不整合面的地质属性；详细对比、追踪该不整合面，研究泥盆系—石炭系残余地层的分布，编制二叠纪前古地质图；结合加里东秦祁洋的演化历史，探讨断陷槽的形成机理；进而依据礁滩地震相特征，预测该区泥盆系—石炭系的油气勘探前景。研究结果表明：①该不整合面可能为泥盆系的底界面，主要分布于文星—中江—绵阳老关庙一带，其上为泥盆系—石炭系残余地层；②泥盆系—石炭系残余地层呈现出断陷槽的特征，并且存在着多个断陷；③断陷槽可能为秦祁洋在奥陶纪—石炭纪期间扩展，于龙门山裂谷内形成的次级断陷；④以川西断陷槽为中心，泥盆系—石炭系礁滩相在其两侧对称分布，规模大、礁滩相特征明显。结论认为，川西坳陷泥盆系—石炭系发育礁滩相，其上叠置二叠系礁滩相，下伏寒武系生烃中心，具有多层系立体勘探的有利条件和良好的油气勘探前景。