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961.
阐述了辽宁地震信息网络Web页面设计风格和Web页面制作过程中的主要技术难点及其解决方法,对更好地创建Web页面,使网页制作从文字界面向图文并茂、生动活泼的图形和多媒体界面发展有一定的借鉴作用。  相似文献   
962.
太阳活动,El Nino对北京地区降雨的影响及预测   总被引:4,自引:1,他引:3  
本文通过对北京地区1900年以来雨量,气温与太阳活动,厄尔尼诺的相关处理分析,得出一种预测北京地区年雨量的数学模型,已准确预测了1996,1997年的年雨量,对1998年预测为750mm~800mm。  相似文献   
963.
我国作为海洋大国,拥有广阔的海域和丰富的海洋资源。在全球海洋布局的时代背景下,加快海洋强国建设成为重中之重。国家开展海洋强国建设需要全民海洋意识的全面提升,由此海洋意识教育显得尤为重要。文章根据多年工作经验,从各方面研究数据出发,分析了海洋意识教育的含义以及加强海洋意识教育的重要性。根据我国国民海洋意识调查的现状,从基础教育、高等教育和大众宣传等方面提出了加强海洋意识教育的举措建议。最终得出应加强我国海洋意识教育,建设过硬的海洋人才队伍,以社会主义核心价值观为导向,加快我国海洋强国建设的步伐。  相似文献   
964.
We compare two methods for estimating the natural source zone depletion (NSZD) rate at fuel release sites that occurs by groundwater flow through the source zone due to dissolution and transport of biodegradation products. Dissolution is addressed identically in both methods. The “mass budget method”, previously proposed and applied by others, estimates the petroleum hydrocarbon biodegradation rate based on dissolved electron acceptor delivery and dissolved biodegradation product removal by groundwater flow. The mass budget method relies on assumed stoichiometry for the degradation reactions and differences in concentrations of dissolved species (oxygen, nitrate, sulfate, reduced iron, reduced manganese, nonvolatile dissolved organic carbon, methane) at monitoring locations upgradient and downgradient of the source zone. We illustrate a refinement to account for degradation reactions associated with loss of reduced iron from solution. The “carbon budget method,” a simplification of approaches applied by others, addresses carbon‐containing species in solution or lost from solution (precipitated) and does not require assumptions about stoichiometry or information about electron acceptors. We apply both methods to a fuel release site with unusually detailed monitoring data and discuss applicability to more typical and less thoroughly monitored sites. The methods, as would typically be applied, yield similar results but have different constraints and uncertainties. Overall, we conclude that the carbon budget method has greater practical utility as it is simpler, requires fewer assumptions, accounts for most iron‐reducing reactions, and does not include CO2 that escapes from the saturated to the unsaturated zone.  相似文献   
965.
Monitoring the Earth's natural pulse electromagnetic field (ENPEMF) signal is a geomagnetic detection approach for the Earth internal and external studies, and it provides a reference for earthquake prediction. In this paper, the Ensemble Empirical Mode Decomposition–Wigner Ville Distribution (EEMD–WVD) method is used to process the time sequences of the ENPEMF signal detected by GR‐01 receiving devices during the Lushan MS7.0 earthquake (April 20th, 2013). By obtaining the intrinsic mode function (IMF), the time–frequency–amplitude joint distribution and the energy spectrum of the ENPEMF signal, the suspected anomalies before the earthquake could be shown. The results illustrate the ENPEMF signal before an earthquake and its time–frequency characteristics based on an EEMD–WVD algorithm, proving useful information about the anomalies around the time of the earthquake.  相似文献   
966.
A numerical investigation regarding the seismic behavior of complex-3D steel buildings with perimeter moment resisting frames (PMRF) and interior gravity frames (GF) is conducted. The interior connections are assumed to be first perfectly pinned (PP) and then semi-rigid (SR); the two model responses are compared. Three steel building models representing low-, medium- and high-rise buildings, and several strong motions are used. The relative stiffness of SR connections is calculated according to the Richard Model and the Beam Line Theory. The Ruaumoko Computer Program is used to perform the required step-by-step nonlinear seismic analysis. Results indicate that interstory shears and interstory displacements at PMRF may be significantly reduced when interior connections are modeled as SR. Average reductions of up to 20, 46 and 11% are observed for interstory shears, for low-, medium-, and high-rise buildings, respectively. The corresponding reductions for interstory displacements are about 14, 44 and 15%. The contribution of GF to the lateral resistance is considerable, which significantly increases when the connections are modeled as SR; relative contributions larger than 80% are observed. The dissipated energy (DE) at PMRF is larger for the buildings with PP than for the buildings with SR connections indicating that damage at PMRF is reduced. Thus, the effect of the stiffness and the DE at interior connections should not be ignored. However, the design of some elements, particularly columns of the GF, has to be revised; these members may not be able to support the loads produced by the neglected lateral contribution if they are not properly designed.  相似文献   
967.
Taking the 2013 Tongliao MS5. 3 earthquake as a research subject, on the basis of statistical analysis of earthquake sequence using the HypoDD location method and focal mechanism solutions,the paper analyzes and discusses the relationship between the ML4. 4 and MS5. 3 earthquakes. The results show that the Tongliao MS5. 3 earthquake occurred under the background of medium-small earthquakes long-term quiescence and short-term enhancement in the epicentral area. The results of accurate seismic location shows that the Tongliao MS5. 3 earthquake sequence is distributed in the NW direction,extending 10 km,and the ML≥3. 0 aftershocks are concentrated south of the mainshock. The distance between the MS5. 3 mainshock and the ML4. 4 foreshock is about 1. 8 km,with a focal depth of 7. 208 km and 7. 089 km,respectively,their focal location is very close,and may have occurred on the same fault plane. The results of focal mechanism shows that the Tongliao MS5. 3 earthquake is of the strike-slip type,the focal mechanism of aftershocks are disordered,and with time lapse,the type is changed from strike-slip to thrust and normal faulting. The bigger foreshocks had similar focal mechanism and were all normal fault types,which exhibits to some extent,an obvious crustal medium anisotropy in the epicentral area before macroscopic rupturing,as represented by alignment fractures,with stress action enhanced,this"consistency"of seismic precursor regime would gestate the mainshock. According to the characteristics of temporal-spatial distribution of earthquake sequence and similarity of focal mechanism,we judge that the Tongliao MS5. 3 earthquake sequence is a foreshock-mainshock-aftershock type.  相似文献   
968.
为研究带空心钢球的钢管混凝土柱的抗震性能,以空心率和含钢率为参数,设计制作9个内置空心钢球的圆截面钢管混凝土柱和3个薄壁圆截面钢管混凝土柱,并进行拟静力试验,结合破坏形态通过延性系数和累积耗能等参数探讨了试件的抗震性能。研究结果表明:含钢率对内置空心钢球的薄壁圆形钢管混凝土柱极限荷载,峰前耗能的影响较大,空心率对试件延性系数,峰后耗能的影响显著;内置空心钢球的薄壁圆形钢管混凝土柱较实心薄壁圆形钢管混凝土柱极限荷载有所降低;试件水平荷载时程曲线的"V"字形波动的折线可以较直观的反映出结构损伤破坏过程,并在曲线数形与试验现象关联上和滞回曲线形成较好的一致性;可以通过优化内置空心钢球的大小和壁厚设计钢管混凝土柱,并取得与实心钢管混凝土柱同样的抗震性能,为同类钢管混凝土组合结构的设计提供了依据。  相似文献   
969.
Hu  Xiumian  Li  Juan  Han  Zhong  Li  Yongxiang 《中国科学:地球科学(英文版)》2020,63(8):1041-1058
A deeper understanding of hyperthermal events in the Earth's history can provide an important scientific basis for understanding and coping with global warming in the Anthropocene. Two types of hyperthermal events are classified based on the characteristics of the carbon isotope excursion(CIE) of the five representative hyperthermal events in the Mesozoic and Cenozoic. The first type is overall characterized by negative CIEs(NCHE) and represented by the Permian-Triassic boundary event(PTB, ~252 Ma), the early Toarcian oceanic anoxic event(TOAE, ~183 Ma), and the Paleocene-Eocene Thermal Maximum event(PETM, ~56 Ma). The second type is overall characterized by positive CIEs(PCHE) and represented by the early Aptian oceanic anoxic event(OAE1 a, ~120 Ma) and the latest Cenomanian oceanic anoxic event(OAE2, ~94 Ma).Hyperthermal events of negative CIEs(NCHE), lead to dramatic changes in temperature, sedimentation, and biodiversity. These events caused frequent occurrence of terrestrial wildfires, extreme droughts, acid rain, destruction of ozone layer, metal poisoning(such as mercury), changes in terrestrial water system, and carbonate platform demise, ocean acidification, ocean anoxia in marine settings, and various degree extinction of terrestrial and marine life, especially in shallow marine. In contrast,hyperthermal events of positive CIEs(PCHE), result in rapid warming of seawater and widespread oceanic anoxia, large-scale burial of organic matter and associated black shale deposition, which exerted more significant impacts on deep-water marine life,but little impacts on shallow sea and terrestrial life. While PCHEs were triggered by volcanism associated with LIPs in deep-sea environment, the released heat and nutrient were buffered by seawater due to their eruption in the deep sea, thus exerted more significant impacts on deep-marine biota than on shallow marine and terrestrial biota. This work enriches the study of hyperthermal events in geological history, not only for the understanding of hyperthermal events themselves, large igneous provinces, marine and terrestrial environment changes, mass extinctions, but also for providing a new method to identify the types of hyperthermal events and the inference of their driving mechanism based on the characteristics of carbon isotopic excursions and geological records.  相似文献   
970.
人工湿地研究现状与展望   总被引:7,自引:0,他引:7  
成水平  王月圆  吴娟 《湖泊科学》2019,31(6):1489-1498
自1950s开始系统性研究以来,人工湿地研究日趋深入,也得到了广泛的应用.本文基于文献报道,对人工湿地研究的历程特别是我国的研究进行了分析,分为起步探索、迅猛发展和规范应用三个阶段.梳理了人工湿地的研究现状,主要集中在如何提高脱氮除磷效率、对新兴污染物的去除、人工湿地根区微生物结构与功能以及人工湿地模型四个方面.核心还是提高人工湿地对污染物的去除效率并解释其机理.未来需要长期监测数据支撑的理论实践结合的设计规程;进一步揭示人工湿地的生物过程;建立合理简化的模型,对系统进行准确预测.  相似文献   
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