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991.
地震监测是一项对震情应急反映要快 ,系统网络安全性要求较高的工作 ,Windows终端就是建立在系统网络的基础上 ,以允许多个用户同时登录到一台服务器并运行服务器上应用的网络系统终端。它具有成本低 ,安全性好 ,解决网络阻塞能力强 ,应急反映速度快等优势。“Windows终端”的局域网模式是目前应用较为广泛 ,使用性能较好的一种网络连接方式。本文系作者在参加福建省地震局“1 0 5 - 0 3”十五重点项目中 ,对监测中心的台网监测网络系统建设的思考。目前我局新办公楼即将竣工 ,我监测中心新的办公写字间网络系统连接方式 ,选择“Windows终端”不失为一个较好的方案。  相似文献   
992.
We collect a sample of 51 Fermi-detected gamma-ray loud blazars with known radio Doppler factors and study properties of the Doppler factors of blazars at optical,X-ray and gamma-ray bands.A basic assumption is that the emission from the radio to gamma-ray bands of the blazars are produced by the nonthermal radiation of accelerated particles in a jet.Our results show that (1) the Doppler factors of blazars are a function of frequency,with the Doppler factor decreasing with frequency from the radio to X-ray ...  相似文献   
993.
The application of fiber reinforced plastic(FRP),including carbon FRP and glass FRP,for structural repair and strengthening has grown due to their numerous advantages over conventional materials such as externally bonded reinforcement(EBR) and near-surface mounted(NSM) strengthening techniques.This paper summarizes the results from 21 reinforced concrete beams strengthened with different methods,including externally-bonded and near-surface mounted FRP,to study the strain coordination of the FRP and steel rebar of the RC beam.Since there is relative slipping between the RC beam and the FRP,the strain of the FRP and steel rebar of the RC beam satisfy the quasi-plane-hypothesis;that is,the strain of the longitudinal fiber that parallels the neutral axis of the plated beam within the scope of the effective height(h 0) of the cross section is in direct proportion to the distance from the fiber to the neutral axis.The strain of the FRP and steel rebar satisfies the equation:ε FRP =βε steel,and the value of β is equal to 1.1-1.3 according to the test results.  相似文献   
994.
We present a paleolimnological record from shallow Lake Wuliangsu in the Yellow River Basin, north China, using a short (56 cm) sediment core. Our objective was to investigate environmental changes in this semi-arid region over the past ~150 years. The sediment core was dated using 137Cs and 210Pb. We examined stratigraphic trends in core lithology, nutrients, stable isotopes (δ13C and δ15N) and trace element concentrations in the Lake Wuliangsu core to discern between natural sediments and those affected by human agency. A lithologic transition from yellow, coarse-grained sediment to grey, fined-grained sediment marked the lake’s formation about 1860. Until ~1950, sediments displayed relatively low and constant heavy metal concentrations, indicating little human influence. In the 1950s, enrichment factors (EFs) increased, reflecting greater impact of human activities. Carbon and nitrogen stable isotopes in organic matter (OM), along with heavy metal concentrations, were used to infer past shifts in trophic state and identify pollutants that came from agriculture, industry and urbanization. In the late 1950s, the first evidence for environmental change is recorded by increases in total organic carbon (TOC), total organic nitrogen (TN), TOC/TN, EFs, δ13C and a decrease in δ15N. After about year 2000, a more rapid increase in trophic status occurred, as indicated by greater total phosphorus (TP), EFs, δ15N and lower δ13C values. Changes in isotope and TOC/TN values in the lake sediments may reflect a shift in lake ecology during this period. The first increase in trophic status during the late 1950s was mainly a result of agricultural development in the catchment. In contrast, the change after ca. AD 2000 was driven largely by urban and industrial development. Agreement between paleolimnologic data from Lake Wuliangsu, and both instrumental and written records, indicates that the lake sediments provide a reliable archive for investigating the formation and environmental history of the lake.  相似文献   
995.
运用2007年河南省和全国投入产出表基础数据,从纵横两个方面比较分析了河南省产业关联特征。研究结果表明:河南省农业前向、后向关联能力较强,基础地位突出;矿产资源采掘及加工业优势突出;制造业尤其是装备制造业辐射力不足,高端生产性服务业及公共服务业前向、后向关联效应较弱,服务消费不足;服务业增加值率较低,并且制造业对传统生产性服务业中间需求比重明显高于全国水平,而对高端生产性服务业的中间需求低于全国水平。  相似文献   
996.
将地区划分为城区和农村两区域系统,构建一个综合考虑城乡劳动力迁移、环境污染、农业生产效率、城乡贸易和公共服务基础设施建设等诸因素的核心-边缘模型,以深入系统地考察城乡差距问题,对于解决现有城乡问题有着重要的理论和现实意义.研究表明:劳动力向城区迁移有助于提高城镇和农村居民的生活效用水平,并缩小城乡差距;环境污染物排放对居民生活造成负面影响,生产活动的集聚对城乡差距的影响取决于污染的危害程度;倘若农业生产的环境影响较小,农业生产效率的提高可以缩小城乡差距;城乡间交通基础设施建设、城区交通及通信设施建设和产业集聚等将提高城镇居民效用水平,拉大城乡差距.  相似文献   
997.
This paper is about the development of a decision‐support system for water‐pollution management and environmental planning. More specifically, the paper first presents the overall concept and the system architecture of a generic environmental decision‐support system (EDSS) and then develops an EDSS especially for analysing the tidal flow pattern and water quality of China's Pearl River Delta. The EDSS developed here employs the object‐oriented approach to design the environmental database and utilizes the system integration technology to develop the overall user‐friendly system that operates in the Windows environment. Furthermore, the system can be expanded to facilitate automated model selection and analysis. The EDSS should be of value for managing water quality of river networks with complicated flow patterns, such as that found in the Pearl River Delta.  相似文献   
998.
川东北地区下三叠统飞仙关组为浅海碳酸盐岩夹泥页岩与蒸发岩序列,而在碳酸盐岩台地边缘通常发育一些白云石化的鲕粒滩。这些鲕粒滩白云岩储集层是川东北地区主要的产气层,一些学者认为该套白云岩为大气淡水与海水的混合水白云石化成因,另外一些学者将其视为回流—渗透白云石化成因。飞仙关组鲕粒滩白云岩稳定同位素氧值一般为-6.73‰~-3.65‰(PDB),平均值为-4.89‰(PDB)(罗家寨地区为-10.81‰(PDB)),稳定同位素碳值一般为+0.57‰~+3.00‰(PDB)。对基质和孔洞中充填的鞍状白云石和亮晶白云石胶结物而言,稳定同位素87Sr/86Sr值为0.70735~0.70800。这些有关鲕粒滩白云岩的数据表明白云石化作用是在埋藏条件下进行的。在测定流体包裹体的均一化温度后,计算出白云石化流体稳定同位素氧成分(δ18O白云石-δ18O=[3.2×106 T-2]-1.5,来自 Friedman 和 ONeil(1977)),其平均值约为+4‰(SMOW)。根据流体稳定同位素氧、碳成分与海水蒸发时流体盐度的正相关性,计算出流体δD平均值约为+25‰(SMOW)。流体包裹体盐度测定表明,白云石化流体是一种超盐度卤水,其盐度是海水的数倍,白云石化的温度为90~130℃。由于下三叠统鲕粒滩白云岩的稳定同位素氧和碳成分与上二叠统生物礁白云岩的稳定同位素氧和碳成分类似,因此,它们的白云石化流体很可能是同一来源。然而,这一结论还有待于进一步研究。  相似文献   
999.
漳州地热田基岩裂隙水系统温度分布特征   总被引:1,自引:0,他引:1  
为研究漳州地热田基岩裂隙水系统温度分布特征,建立了新的三维基岩裂隙水系统概念模型,并利用Fluent软件求解模型。结果表明:基岩裂隙热水温度场受到断裂区的强烈控制,在北东—南西向断裂中,强烈对流形成的高温热柱刺穿了基岩顶部形成热田高温中心;基岩热流在断裂区中部高温区达到最大,在北东—南西方向上最大值为343.02mW/m2,在北西—南东方向最大值为368.72mW/m2,并向边缘逐渐降低;第四系孔隙水的存在和运动使得地表热流的最大值和局部值降低。未来漳州热田应加强深部温度的测量研究。  相似文献   
1000.
Near-surface atmospheric dust in Changsha city of China was analyzed in terms of morphological and geochemical composition. Morphological and chemical composition of the dust particles were analyzed by environmental scanning electron microscopy coupled with an energy-dispersive X-ray analyzer. Results indicated that the atmospheric dusts were mainly composed of spherule, plate, irregularly shaped and agglomerate, which contains variable sizes and amounts of particles. The dust particles could be categorized into five groups based on their chemical characteristic: Al-, Si-, Ca-, C-rich particles and aggregate. These particles and aggregate could be directly related to nearby polluting activities, such as building construction, traffic emission and coal combustion. The X-ray diffraction results show that the main minerals for atmospheric dust are gypsum, quartz and calcite. Mica, halloysite, montmorillonite, hematite, brushite, zeolite, sepiolite, feldspar, alite, dickite, SiS2, Fe6(OH)2CO3, FeSO4, CdSO4, Pb(NO)2O3, Al2SO4(OH)4, As2O3SO3, (NH4)2SO4, NH4Cl, K(NH4)·Ca(SO4)2·H2O are also detected in samples. The identification of heavy metals shows that the concentrations of Cr (403.5?mg?kg?1), Cu (126?mg?kg?1), Zn (1541.5?mg?kg?1), Cd (2.5?mg?kg?1) and Pb (348?mg?kg?1) in the atmospheric dust are much higher compared to background value of soil. It indicates that the heavy metal (Cr, Cu, Zn, Cd and Pb) in the atmospheric dust is mainly due to human activities. The identification of main sources of atmospheric dust collected in typical areas can help to control the polluting sources in urban area.  相似文献   
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