Structural Evolvement of Heating Treatment of Mg/AI-LDH and Preparation of Mineral Mesoporous Materials

Although hydrotalcite, or layered double hydroxides （LDHs）, is not a common mineral, it is an important material that can be easily synthesized in laboratory. In this study, structural evolvement and BET surface area changes of heat treated Mg/AI-LDH is evaluated by XRD, TEM and N2-BET analyses. The results indicate that the magnesium-aluminum LDH with carbonate as interlayer anion, periclase-like oxides was formed at temperatures of 400-800℃. Meanwhile, 2-3 nanometer mesoporous were formed during decomposition of LDH. However, the heat treated samples still preserve the morphology of the original LDH plates. Periclase-like formed from LDH heat treatment may re-hydrolyze and recover the structure of LDH. However, crystallinity of the recovered LDH is lower than that of the original LDH. This heat treatment will result in formation of （Mg, Al）-oxide nano-crystals and nanopores among the nano-crystals. When heating temperature exceeds 1000, the periclase-like （Mg, Al）-oxide is transformed into a composite with periclase （MgO） and spinel phases. The periclase can be re-hydrolyzed and dissolved in HCl solution. After acid treatment, the sample with a high surface area is composed of spinel nano-crystals and nanopores among them. Our results will provide a new and economic way to synthesize mesoporous materials through pathways of phase transformation of precursor materials with different composition.     

中国大气本底观测发展概述

中国早期的大气本底观测网建设起步于上世纪80年代初，并于10a后基本建成。目前，中国气象局、中国科学院在原有观测站的基础上各自建设和发展着自己下属的大气本底观测网络。全球大气观测网给出了一整套开展大气本底观测的技术标准，各国均予以严格遵循。20多年来，中国大气本底观测工作在基础数据积累以及观测标准制定等方面取得了较大进展，与此相关的科学研究也取得了长足进步。最后对中国大气本底观测发展过程中存在的一些问题进行了探讨。     

宁夏产业结构演进与经济增长系统研究

产业结构的演进与升级一定程度上反映了区域经济的发展阶段与发展能力。以1978-2003年的统计数据为基础,系统研究了宁夏产业结构变迁与区域经济发展的关系。研究结果表明:(1)宁夏产业结构的变化符合产业结构变迁的一般规律,但产业结构高度化水平依然低下;(2)宁夏产业结构变迁的空间集聚效应明显;(3)宁夏产业结构演进对经济增长的影响形成产业结构偏离为正,竞争力偏离份额为负型、产业结构偏离为正,竞争力偏离份额为正型和产业结构偏离为负,竞争力偏离份额为正型三种类型;(4)产业结构变迁对各地区经济增长的影响差异较大。研究指出,在西部大开发和区域经济一体化进程中,以及在国家和地区产业政策调整的背景下,建立产业协调与分工合作机制,发展特色优势产业,推进重点地带布局开发,形成区域性“群落型”经济优势,成为新时期宁夏产业结构调整的战略选择。     

沈阳地区土地沙化过程与防治措施

地处我国北方半湿润森林与农区过渡的农牧交错带上的沙地在区域上具有边缘性与过渡性,对该区域土地沙化研究具有理论意义和实践意义。本文分析了从属于此类性质的沈阳的康法和柳绕地区土地沙化现状与特征,揭示了土地沙化过程及规律,并提出了生态建设的主要措施,对区域经济发展有一定的指导意义。     

基于“3N”理念的德化县旅游资源开发思路

现代社会的都市化及人工化,引发人类种种生理、心理问题,生活在钢筋水泥森林中的都市人逃出“现代围城”的欲望日益强烈,让身心回归真正的自然,于是“3N”旅游应运而生。本文结合德化县的实例,探讨“3N”旅游及其产品的开发问题。     

Climatic characteristics of summer high temperature and assessment methods in the large cities of North China

Based on the high temperature data of June to August in 1961-2000 in North China, the high temperature weather processes are investigated, and a more complete data set for severe high temperature processes is created. The climatic characteristics of adverse high temperature weather in Beijing, Tianjin, Shijiazhuang, Jinan and Taiyuan are analyzed respectively. The major features of the East-Asia Subtropical High and Transformed Continental High are discussed. The outcomes indicate that the influence of both East Asia Subtropical High and Transformed Continental High on these weather events varies, by a larger margin, from one city to another over North China and they are also closely related to the relative humidity. It is found that the behaviours of East-Asia Subtropical High and Transformed Continental High are the major important systems that give rise to the summer high temperature weather over the region. Based on these findings, the 5-day, 10-day and monthly assessment models for such high impact events have been developed. The assessment outcomes prove to be useful in assessing severe high-temperature events in major cities of North China.     

Climate change in Mt. Qomolangma region since 1971

Using monthly average, maximum, minimum air temperature and monthly precipitation data from 5 weather stations in Mt. Qomolangma region in China from 1971 to 2004, climatic linear trend, moving average, low-pass filter and accumulated variance analysis methods, the spatial and temporal patterns of the climatic change in this region were analyzed. The main findings can be summarized as follows: (1) There is obvious ascending tendency for the interannual change of air temperature in Mt. Qomolangma region and the ascending tendency of Tingri, the highest station, is the most significant. The rate of increasing air temperature is 0.234 oC/decade in Mt. Qomolangma region, 0.302 oC/decade in Tingri. The air temperature increases more strongly in non-growing season. (2) Compared with China and the global average, the warming of Mt. Qomolangma region occurred early. The linear rates of temperature increase in Mt. Qomolangma region exceed those for China and the global average in the same period. This is attributed to the sensitivity of mountainous regions to climate change. (3) The southern and northern parts of Mt. Qomolangma region are quite different in precipitation changes. Stations in the northern part show increasing trends but are not statistically significant. Nyalam in the southern part shows a decreasing trend and the sudden decreasing of precipitation occurred in the early 1990s. (4) Compared with the previous studies, we find that the warming of Mt. Qomolangma high-elevation region is most significant in China in the same period. The highest automatic meteorological comprehensive observation station in the world set up at the base camp of Mt. Qomolangma with a height of 5032 m a.s.l will play an important role in monitoring the global climate change.     

基于土质边坡塑性极限分析条分法的可靠度计算方法研究

从土塑性极限分析上限定理出发,以土质边坡塑性极限分析条分法为基础,在引入可靠性分析方法(JC法)后,建立了土质边坡塑性极限分析条分法可靠度极限状态方程,并推导得到了塑性极限分析条分法可靠度计算公式。这种方法实现了定值计算向不确定性计算的转变,同时可靠度指标的计算结果具有概率的意义。     

下庄铀矿田337矿床成矿流体稀土元素示踪

337铀矿床位于下庄矿田东缘,区内发育近EW向、NNE向构造裂隙群及NW向辉绿岩和正长岩脉体,发育以碱性为主的多种围岩蚀变。区内矿床主要赋矿围岩的稀土元素特征属壳源型。矿石内金属矿物以沥青铀矿为主,矿石的LREE/HREE比值为3.25,Sm/Nd比值平均为0.307,Ce/Yb比值为7.127,这些数据都显示出成矿流体具有较深来源。矿石较围岩亏损稀土元素尤其是轻稀土元素,稀土元素分布模式平缓,与幔源辉绿岩特别是与正长岩的稀土元素分布模式相近,负铕异常比围岩更为强烈,反映成矿流体的来源具有幔源性。结合区域地质特征,可以认为337矿床成矿流体来源具有幔源性质。     

USB总线与CAN总线协议转换器设计

现场总线(F ield bus)是将自动控制系统中底层的现场控制器和现场智能仪表设备互连的实时控制通讯网络,是5C(Computer,Control,Commun ication,CRT,Change)技术相结合的产物。CAN(Control Area Network)总线是现场总线的一种,广泛应用于汽车行业、机械工业、家用电器、传感器等领域,已经形成国际标准,是被公认的几种最有前途的现场总线之一。提出了一种通过计算机USB接口实现现场总线CAN与计算机(服务器)之间通信的方案。具体介绍了使用USB总线接口芯片CH372和独立的CAN控制器SJA1000实现的硬件电路设计方法、本地端软件的编写方法,给出了主要程序模块的流程。