用爆炸源和天然地震源对圣安德烈斯断层成像

现有证据说明,断层带的不均匀性可能在地震破裂局域化中起决定性的作用(Aki,1995)。这种不均匀性可以呈现多种形式,如物理性质(弹性、孔隙流体压力等)随空间的变化,或断层面的复杂性(弯曲、错断等)。P波和S波速度(v_p和v_S)结构的高分辨率三维模型以及精确的震源为研究断层带不均匀性对破裂局域化的作用     

Vertical seismic absorber utilizing inertance and negative stiffness implemented with gas springs

A novel implementation of negative stiffness elements(NSEs) is proposed, utilizing industrial grade nitrogen gas springs as pre-stressed stiffness elements in a configuration with lever arms. This NSE is combined with an inerter to form a stiff dynamic absorber(SDA) for vertical seismic protection of structures with base isolation. The SDA is optimized to minimize vertical accelerations while ensuring static structural integrity, excellent damping performance and containment of relative displace...     

世界原子能的地理分布

发展阶段原子能的发展历史可简略分为四个阶段。第一阶段包括五十年代中期。这个时期出现了第一批原子能电站和现有的各种反应堆类型。每二阶段从五十年代末期到六十年代末期。这段时间由于原子能电站设备价值昂贵,反应堆功率低,一些国家又发现了大型石油天然气产地,因此与热电站比较竞争能力低。原子能电站的发展陷入低潮。     

ADULT DRAGONFLY COMMUNITIES IN TROPICAL RIVERS OF THE NORTHERN PENINSULAR MALAYSIA： SPECIES COMPOSITION, BIOTOPE AND HOST PLANT PREFERRENCES

1INTRODUCTION Manyfactorshavebeenlinkedwithobserved patternsofodonatediversity.Eachhabitatisdifferent andpresentsitsownopportunitiesforexploitationby welladaptedspecies(Krebs,1989).Theyaresensi tiveresponderstonewlycreatedphysicalandtogether withphysiogra…     

Integrated geophysical surveys on railroads in permafrost areas

The zones of thawed ground in the permafrost area are most dangerous from engineer-geologist effect point of view. Detection of such zones, as making forecast of their movement is the main task of engi...     

I AND UTILIZATION IN KUNMING LAKE REGION, YUNNAN

The Kunming Lake, with an area of 324 sq. kin. during its flood water time, is the largest lake in Eastern Yunnan. More than twenty streams from the surrounding mountains empty into the lake which is drained by the TangLang River to the upper Yangtze. Around the Kunming Lake is an extensive     

坦桑尼亚城市体系演变与空间分布特征

坦桑尼亚是东部非洲城市化发展最快的国家之一,长期与中国保持密切合作关系。坦桑尼亚城市体系及空间分布研究可为当地城市发展决策及中-坦在城市建设方面的合作提供科学依据。基于坦桑尼亚独立以来全国人口普查资料及自然环境数据,在界定城市地区的基础上,运用位序-规模法则、标准差椭圆、城市发展适宜度等分析方法,定量分析了坦桑尼亚独立以来的城市体系演变过程及现阶段空间分布特征。研究发现:(1)坦桑尼亚城市规模分布经历了"不均衡-均衡-不均衡"的发展过程,达累斯萨拉姆在城市体系中长期占有绝对主导地位,且在未来一定时期内仍将持续;(2)坦桑尼亚城市空间上呈现"西北-东南"的分布格局,中心位于中部偏东省份,城市扩张方向以西北、西部以及西南方向为主;(3)城市的空间分布受河流、植被、高程、地形起伏度、降雨量等自然环境因素影响,且高等级城市倾向于分布在水土环境条件较好的地区;(4)城市发展高适宜度区位于东非大裂谷东、西支之间的中央高原,以及东部沿海和东南部高原一带,城市发展低适宜度区位于东北部高地及其向西南延伸的南部高地,整体上自西北向东南呈现"高-低-高"的空间分布格局。     

WATER QUALITY STUDIES IN MALAYSIAN DISUSED MAN MADE LAKFS FOR SUITABILITY OF AN AQUACULTURE PROJECT

A study has been conducted on the status of water quality in two disused man made lakes, which have potential for cage aquaculture project. This study highlights the quality of water analyzed with reference to various physical - chemical parameters in two selected lakes and their suitability for fish farming. A number of parameters were measured including the amount of NH3 - N, NO3 - N, NO2 - N and total phosphorus while in - situ measurement including DO, pH, temperature, conductivity, TDS and Secchi disk visibility. Beside the physical -chemical of water, the location, morphometry and climate conditions were also investigated. The chemical data analyzed for six months indicated that Lake A and Lake B are characterized by relatively high DO, slightly neutral pH and low TSS. The concentration of NH3 -N and NO2 -N was very low （0. 058 mg/L and 0. 04 mg/L, respectively） and total phosphorus was usually in low concentration and sometimes would seem negligible. Besides, NO3 - N occurred in slightly higher concentration （1.75 mg/L）. Results obtained indicated that the study site has high potentiality for development of inland fisheries practices.