自动气象站防雷电源切换器的设计开发

自动气象站设备经常被从交流电源线路感应进来的雷击而造成损坏,目前安装的各种防避雷器还不能完全有效防止该现象的发生。如果能用两组蓄电池,交替给设备供电,就能将交流电源与设备隔离,起到防止电源线感应来的雷电击毁设备的事故。设计开发的防雷电源切换器通过检测蓄电池的供电电压,控制两微型电机的正反转,再经电机的传动装置,带动接点移动,达到两组蓄电池交替供电和充电。调整电机的走动行程,可使充电器与设备的间距达到8~10 cm,起到了电源防雷的目的。     

北京市感染性腹泻疾病的医疗气象预报与应用研究

通过分析北京市海淀区感染性腹泻病发病情况与北京市观象台地面气象要素的相关关系,建立感染性腹泻病医疗气象分级预报及风险水平评估模式.收集海淀区2004-2006年逐日菌痢周发病数和同期气象因素资料,建立数据库,分析气象因素与肠道传染病发病率的关系,并采用多元回归概率分级技术,建立感染性腹泻病医疗气象分级预报(划分5个等级)及风险水平评估模式.结果表明,感染性腹泻病发病与水汽压的相关程度很好,单相关系数为0.8340.在所有候选预报因子中,它的方差贡献占70.5%.其他方差贡献较大的因子,还有平均风速、气温日较差等.在感染性腹泻病医疗气象分级预报及风险水平评估模式中,如果预报等级与实际等级相差≤±1级统计为正确,感染性腹泻病医疗气象分级预报模式组的平均预报正确率可达98.5%.其中,预报等级与实际等级完全吻合的正确率可到62.9%～66.4%(指6个预报时效).该模式预报结果可较好地为2008年奥运会提供肠道传染病预防服务,为北京各级疾病预防控制中心指导广大城乡居民卫生防疫提供科学依据.     

应用弹塑性反应谱对IDA方法的改进研究

针对传统IDA方法中结构的加速度反应远高于SPO分析结果的现象,采用弹塑性反应谱作为IDA的烈度度量,同时给出随地震烈度改变而不断变化的屈服强度系数,提出了改进的IDA方法,更有效地考虑了结构的非线性地震反应特征。实际工程分析表明,改进的IDA方法能够体现结构的非线性受力反应,同时兼顾结构的动力反应特征,与SPO曲线和由规范计算得到的结构承载力有更好的可比较性。     

油气化探异常模式

以判断深部油气藏的性质和保存状态,为油气勘探部门提供可靠的地球化学依据。化探是油气勘查的一种手段,它建立在烃类垂向微运移的理论基础之上。通过对油气化探指标的讨论,认为土壤中的次生烃类、热释汞和甲烷同位素是油气化探的有效指标;讨论了油气化探中异常的形成模式,根据地表地球化学异常特征及形态组合可以判断深部油气藏的性质和保存状态,为油气勘探部门提供可靠的地球化学依据。     

采用高山松最大密度重建川西高原近百年夏季气温

川西高原高山松树轮宽度及最大密度分析结果表明,最大密度年表和宽度年表中可提取的气候信息是不同的,在温暖、水分条件适中的地区,采用树木密度指标分析气候要素的变化是有效的途径。树轮宽度主要受5月降水影响,和西南季风活动有关;而最大密度主要指示了夏季(6￣9月)温度。利用转换函数重建了川西高原近百年来夏季(6￣9月)温度,重建序列的方差解释量为51%,(F=52.099,p<0.0001)。重建序列显示川西高原,30年代之前为偏冷期,30年代到60年代为偏暖期,与四川地区近百年的冷暖时期比较一致。与平原地区的成都相比,高原的升温转折点提前3年,表明高原地区对气温变化的响应更为敏感,川西高原地区可能是四川省气候变化的先兆地区。1983年以后川西高原地区夏季温度呈明显的上升趋势,20世纪90年代夏季温度的滑动平均为近百年的最大值,但在90年代初期仍处于均值线以下,表现为凉夏;90年代后半期表现为夏旱。     

近年来北京沙尘天气特征及成因分析

针对2000-2002年北京沙尘天气增加和2003年沙尘天气迅速减少的现象,统计分析了近几年北京沙尘天气的特征和出现的特点,并从大气环流形势、气候特点、气象要素以及可能影响北京沙尘天气的沙源状况进行分析。2000-2002年春季,我国处于西北气流的控制之下,冷空气势力强,以西或西北路径影响我国。2003年春季亚洲东北部高压脊偏强和日本海气旋较弱,使得冷空气路径偏北,入侵我国的冷空气势力较弱,产生大风沙尘的动力条件减弱。气候特点分析表明,1999-2002年北方大部分地区降水量持续偏少,年平均气温偏高,造成土壤水分蒸发强烈,土壤干燥疏松。2002年冬季至2003年春季,北方地区降水量较常年明显偏多,北京周边地区的主要沙源地一直被积雪覆盖,植被覆盖度扩大,有效抑制了沙尘天气的形成。     

湘西北常页1井下寒武统牛蹄塘组页岩气储层特征

湘西北常页1井为目前国内钻遇海相页岩层段厚度最大的调查井,其下寒武统牛蹄塘组页岩厚度约700m。该套页岩组合以粉砂质页岩、粉砂质页岩夹泥岩、炭质页岩、泥灰岩、钙质页岩、含炭钙质页岩、细晶灰岩、硅质页岩为主,见钙质结核及黄铁矿条带。其底部200m以富有机质炭质页岩为主,石英、长石和黄铁矿总量平均为41.9%,粘土矿物含量平均为27.9%,方解石和白云石含量平均为8.7%,与美国典型页岩储层相似。牛蹄塘组页岩有机碳含量底部为3.9%~17.6%,上部为0.3%~2.1%;平均孔隙度为1.57%,平均渗透率为0.004×10-3μm2。氩离子抛光扫描电镜下页岩微孔隙主要包括矿物晶间(溶)孔、晶间隙、晶内孔,有机质内微孔和微裂缝等。根据比表面-孔径分析,页岩孔喉中值半径最大为6.6nm,平均为5.5nm。综合研究认为牛蹄塘组海相页岩储气能力与孔隙体积、孔隙度、矿物成分、TOC等均有着一定的关系,其中有机碳含量是影响页岩含气量的最主要因素,其次是石英含量、粘土矿物含量、黄铁矿含量、比表面积和BJH总孔体积。利用多元线性回归法,建立了常页1井牛蹄塘组页岩含气量地质模型。     

Petrology,geochemistry and genesis of Kuiqi granite batholith

The Kuiqi granite batholith outcrops in the vicinity of Fuzhou City, Fujian Province and constitutes one of the typical alkali granitic complexes in the “Belt of Miarolitic Granites” extending along the southeast coast of China. The complex is believed to have been emplaced at higher levels of the crust in a tensional fault environment. Petrographically it is composed mainly of aegirine-arfvedsonite granites with early biotite granites scattered. Miarolitic structure and granophyric texture are commonly observed. The Rb-Sr isochron age of the complex is 107.65 m.y. Both petrological and petrochemical studies show that the Kuiqi granite is of A-type. Data on chemical composition, REE pattern and transition elements reveal that there is a close genetic connection between granites and associated volcanic rocks. Thus, syntexistype (I-type) granite, A-type granite and volcanic rocks form a cogenetic “trinity”, in which the A-type granite is usually the latest member of the volcanic-intrusive series.     

The use of nitrate, bacteria and fluorescent tracers to characterize groundwater recharge and contamination in a karst catchment, Chongqing, China

The Qingmuguan subterranean river system is located in the suburb of Chongqing, China, and it is the drinking water source that local people downstream rely on. The study aims to provide a scientific basis for groundwater protection in that area, using a hydrogeological framework, tracer tests, hydrological online monitoring, and hydrochemical and microbiological investigation, including heterotrophic plate count (HPC) and the analysis of denitrifying bacteria (DNB) and nitrobacteria (NB). The tracer tests proved simple and direct connections between two important sinkholes and the main springs, and also proved that the underground flows here are fast and turbulent. DNB and NB analyses revealed that the main recharge to the underground river in the dry season is the soil-leached water passing through the fissures of the epikarst, while in the rainy season, it is the surface water flow through sinkholes. The hydrochemical and microbiological data confirmed the notable impact of agriculture and sewage on the spring water quality. In the future, groundwater protection here should focus on targeted vulnerability mapping that yields different protection strategies for different seasons.     

Study on Distribution Characteristics of Mining Stress and Elastic Energy Under Hard and Thick Igneous Rocks

In the coal measure strata, igneous rocks are often invaded, and their occurrence, size, and distribution form play an important role in mining safety. The breakage of hard and thick igneous rocks easily induces dynamic disasters, such as rock burst, mine seismicity, gas outburst, and surface subsidence, which seriously threaten mine safety production. In view of the working face with overlying hard and thick igneous rocks, the evolution characteristics of mining stress and energy distribution under hard and thick igneous rocks were investigated. Furthermore, the influence law of different horizons and thicknesses of igneous rock on overlying strata movement law, stress distribution, and energy distribution was analyzed based on FLAC3D numerical simulation. Results show that no evident subsidence of the overlying strata exists before the igneous rock is broken. Additionally, the subsidence amount of the overburden is suddenly increased after the igneous rock is broken, thereby showing significant mutability. Before the igneous rock breaks, a high stress area is formed around the goaf, and the stress concentration gradually increases with the increase of the mining scope. After the igneous rock breaks, the coal under high stress is prone to induce dynamic disasters under the action of strong dynamic load. However, the advanced abutment pressure and stored energy rapidly decreased. The accuracy of the numerical simulation is verified by field monitoring. Results of the study are of considerable significance for safe mining of working face under similar geological conditions.