基于时空分配组合的消防设施服务范围计算方法探讨     

詹庆明  庞前聪  周玉红  周俊 《武汉大学学报(信息科学版)》2008,33(4):353-357

基于时空分配组合方法,综合考虑服务时间在主干道路和街区内分配的各种情形,探讨了符合实际需求的消防站点服务范围计算方法.提出了基于多个独立指标的评价消防设施布局方案的方法,对消防规划方案进行评价.最后以武汉市武昌区为例对所提出方法进行了实验,实验结果也验证了该方法的可行性和合理性.  相似文献   

江西省九岭区地质灾害危险性区划     

雷万荣  顾琳娜  程志华  唐春梅  赵均 《上海国土资源》2008,(2):35-38

对九岭区地质灾害发育的基本特征及其地质环境条件进行了概述,并对其形成条件进行了相关性分析;通过对地质灾害发育的基本规律、控制因素、触发因素与地质灾害关系的分析,采用环境地质学原理,建立区域地质灾害空间预测模型,圈定九岭区地质灾害的危险性分区,为实时地质灾害时间预警预报圈定有效的空间靶区。预测单元采用规则的栅格(500m×500m),共14415个单元;评价指标主要包括地形地貌、工程地质岩类、地质构造、破坏地质环境人类工程活动等四大类26个因子;利用GIS技术,提取出相关的数据信息;信息量预测方程:Ii=-1.164X1-0.999X2-0.681X3 …… 0.203X25-0.135X26(其中X1、X2、X3、…X26取1或0,即某单元中存在某种因素时取1、否则取0),据此计算出各单元格的信息量;根据地质灾害危险性分区临界指标,确定单元格的地质灾害危险性等级;合并同类项,并考虑类似的地质、自然环境具有类似的地质灾害问题的原则,进行归并与单元边界线的修改,得出九岭区地质灾害危险性分区。  相似文献   

Multi-cloud model (MCM) method and its applications to the study on asymmetric spectral profiles   总被引：1，自引：0，他引：1  

Xiao-Ma Gu  Jun Lin  Ke-Jun Li  Jing-Ping Dun 《Astrophysics and Space Science》1996,240(2):263-271

A method of multi-cloud model (MCM) is proposed in this paper in order to research asymmetric profiles of spectral line formed by solar discrete active objects aligned along the line-of-sight difection. Based on the MCM method, under the conditions of certain assumptions and approximations, the line-of-sight velocityV and three other physical parameter approximation values, (i.e. Doppler width _D , source functionS and optical depth at line center ₀) within different clouds may be derived simultaneously by fitting both profiles theoretical and observational. An application example of the method withm=3 shows that MCM method is suitable to measure the velocity fields of multi-object at the same time from their non-Gaussian profiles of complex. TheV and _D derived from the method are reliable,S and ₀ are approximation. An influence of the variations of initial values in the parameter on the solution is given as well.  相似文献   

Calorimetric study of the coesite-stishovite transformation and calculation of the phase boundary     

Jun Liu  Letitia Topor  Jianzhong Zhang  Alexandra Navrotsky  Robert C. Liebermann 《Physics and Chemistry of Minerals》1996,23(1):11-16

High temperature drop-solution calorimetry in molten 2 PbO · B₂O₃ at 1044 K for coesite and stishovite polymorphs of silica was carried out to determine the enthalpy of the coesite-stishovite transition. These experiments were performed on high-purity, single-phase samples of coesite and stishovite. Our new value for the enthalpy of the coesitestishovite transition (ΔH ₂₉₈ ⁰ ) is 29.85 ± 0.78 kJ/mol, which is about 35% lower than previously reported by Akaogi and Navrotsky (1984) and Holm et al. (1967), but which compares well with new measurements by Akaogi et al. (1994b). Using these new data, we have calculated the equilibrium phase boundary between coesite and stishovite and obtained a slope, dP/dT=0.0031 (2) GPa/K. This calculated slope is in good agreement with that determined [0.0026 (2) GPa/K] from the in-situ X-ray diffraction study of Zhang et al. (1996).  相似文献   

近海核电厂核素地下水释放通量的模型计算方法     

朱君  李婷  陈超  谢添  张艾明 《吉林大学学报(地球科学版)》2021,51(1):201-211

为了定量计算陵区近海核电站排水管线泄漏情景下核素通过地下水途径向海洋环境的释放通量，以某近海核电站为例进行研究。首先，应用GOCAD软件建立三维地形地质模型，刻画地层的分布、剥蚀以及倾向等特点；然后，运用地下水数值模拟软件FEFLOW精细刻画丘陵区地下水系统的补给、径流和排泄特征；最后，以不被吸附滞留的核素³H和被吸附滞留的核素⁹⁰Sr、¹³⁷Cs为对象，通过实验测定了⁹⁰Sr、¹³⁷Cs在不同岩土介质中的分配系数，模拟计算了排水管线连续渗漏60 a后³H、⁹⁰Sr、¹³⁷Cs在地下水中的放射性分布及释放。结果表明：³H迁移速度基本与地下水流速一致，地下水中的最大放射性浓度为0.285 0 Bq/L，第20 000天时向收纳水域的释放通量达到最大值，约526 Bq/d；⁹⁰Sr吸附性能相对较弱，最大迁移距离约80 m，地下水中的最大放射性浓度为0.032 1 Bq/L；¹³⁷Cs吸附能力较强，相当长的时间内被滞留在管线附近，地下水中最大放射性浓度分别为6.840×10^-3 Bq/L，释放通量为0 Bq/d。由弥散度的不确定分析可知，弥散度越大，地下水中³H的最大放射性浓度越小，向海洋环境的释放通量越多。  相似文献   

扬子东南大陆边缘晚前寒武纪古海洋演化的稀土元素记录   总被引：10，自引：1，他引：9  

伊海生  彭军 《沉积学报》1995,13(4):131-137

本文采用中子活化方法分析了晚震旦～早寒武纪１９件样品的稀土元素组成,发现硅质岩石ＲＥＥ配分形式有着复杂的变化,初步可以划分为五种类型,包括“台地型”、“红海型”、“海水型”及两种特殊的配分形式。剖面上Ｃｅ异常由小到大的演变反映了古海洋底层水由缺氧环境向氧化条件的逐渐转化。正Ｅｕ异常的出现代表了热水沉积事件的存在。  相似文献   

Scattering of elastic waves by a fracture zone containing randomly distributed cracks     

Jun Kawahara  Teruo Yamashita 《Pure and Applied Geophysics》1992,139(1):121-144

We theoretically study the scattering ofP, SV andSH waves by a zonal distribution of cracks, which simulates a fault fracture zone. An investigation is conducted how the geometrical properties of the crack distribution and the frictional characteristics of the crack surface are reflected in the attenuation and dispersion of incident waves, as well as in the amplitudes of the transmitted and reflected waves from the zone. If the crack distribution within the fault zone changes temporally during the preparation process of the expected earthquake, it will be important for earthquake prediction to monitor it, utilizing the scattering-induced wave phenomena.We consider the two-dimensional problem. Aligned cracks with the same length are assumed to be randomly distributed in a zone with a finite width, on which elastic waves are assumed to be incident. The distribution of cracks is assumed to be homogeneous and sparse. The crack surface is assumed to be stress-free, or to undergo viscous friction; the latter case simulates fluid-filled cracks. The opening displacement of the crack is assumed to be negligibly small. The idea of the mean wave formalism is employed in the analysis, and Foldy's approximation is assumed.When the crack surface is stress-free, it is commonly observed for every wave mode (P, SV andSH) that the attenuation coefficientQ ^–1 peaks aroundka1, the phase velocity is almost independent ofk in the rangeka<1 and it increases monotonically withk in the rangeka>1, wherek is the intrinsicS wavenumber anda is the half length of the crack. The effect of the friction is to shift the peak ofQ ^–1 and the corner of the phase velocity curve to the low wavenumber range. The high wavenumber asymptote ofQ ^–1 is proportional tok ^–1 independently of model parameters and the wave modes. If the seismological observation thatQ ^–1 ofS waves has a peak at around 0.5 Hz in the earth's crust is combined with our results, the upper limit of crack size within the crust is estimated about 4 km. The information regarding the transmitted and reflected waves, such as the high wavenumber limit of the amplitude of the transmitted wave etc., allows estimation of the strength of the friction.  相似文献   

张家口市湿地资源现状、问题与保护对策     

毕君  王超  武明录  毛福玲  付芸生 《湿地科学与管理》2006,2(2):29-33

张家口地区有丰富的湿地资源,张家口的河流、湖淖等湿地对京津地区的水资源供应与调节、生物多样性保护、生态环境的平衡与区域可持续发展关系重大,本文对该区域主要湿地现状、导致其退化的主要原因与问题进行了探讨,并提出了当前湿地保护的建议与对策。  相似文献   

Study on the kinetics of iron oxide leaching by oxalic acid   总被引：2，自引：0，他引：2  

Suong Oh Lee  Tam Tran  Yi Yong Park  Seong Jun Kim  Myong Jun Kim   《International Journal of Mineral Processing》2006,80(2-4):144-152

The presence of iron oxides in clay or silica raw materials is detrimental to the manufacturing of high quality ceramics. Although iron has been traditionally removed by physical mineral processing, acid washing has been tested as it is more effective, especially for extremely low iron (of less than 0.1% w/w). However, inorganic acids such as sulphuric or hydrochloric acids easily contaminate the clay products with SO₄²⁻ and Cl⁻, and therefore should be avoided as much as possible. On the other hand, if oxalic acid is used, any acid left behind will be destroyed during the firing of the ceramic products. The characteristics of dissolution of iron oxides were therefore investigated in this study.The dissolution of iron oxides in oxalic acid was found to be very slow at temperatures within the range 25–60 °C, but its rate increases rapidly above 90 °C. The dissolution rate also increases with increasing oxalate concentration at the constant pH values set within the optimum range of pH2.5–3.0. At this optimum pH, the dissolution of fine pure hematite (Fe₂O₃) (105–140 μm) follows a diffusion-controlled shrinking core model. The rate expression expressed as 1 − (2 / 3)x − (1 − x)^2 / 3 where x is a fraction of iron dissolution was found to be proportional to [oxalate]^1.5.The addition of magnetite to the leach liquor at 10% w/w hematite was found to enhance the dissolution rate dramatically. Such addition of magnetite allows coarser hematite in the range 0.5–1.4 mm to be leached at a reasonable rate.  相似文献   

藏西北三岔口地区泥瓮系生物礁特征及其意义          下载免费PDF全文

夏军钟华明  童劲松鲁如魁 《沉积与特提斯地质》2006,26(2):34-41

在羌塘西部的三岔口一带泥盆系拉竹龙组中发现规模较大的生物礁——台地前缘礁。下层礁体厚7．28m，上层礁体厚40.98m。两个礁体均为叠置礁，礁体由礁基、礁核、礁顶组成。剖面显示发育有礁前垮塌角砾、礁格架、礁间及礁后环境。泥盆纪生物礁的发现为羌塘盆地寻找油气资源提供了新思路。  相似文献