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81.
为探究贵州省地震灾害风险薄弱环节,减轻地震灾害风险,以贵州省罗甸县为示范,采用地震危险性概率分析方法对各乡镇进行危险性分析,开展地震灾害承灾体现场抽样调查,通过层次分析法和问卷调查的方式,首次构建乡镇级别的地震灾害风险和减灾能力指标体系,评估各乡镇地震灾害综合指数和程度,计算各乡镇地震灾害风险指数,确定红水河镇为高风险区、罗悃镇为中风险区、木引等7个乡镇为低风险区,并从建筑物设防、地震地质灾害及水库地震等角度剖析罗甸县地震灾害特点,从农村危房改造、移民搬迁、地质灾害防护及交通等方面提出减小地震灾害风险的建议。 相似文献
82.
The formation and evolution of a large amplitude MHD perturbation propagating perpendicular to the magnetic field in a perfectly conducting low plasma is studied. The perturbation is generated by an abrupt expansion of the source region. Explicit expressions for the time and the distance needed for the transformation of the perturbation's leading edge into a shock wave are derived. The results are applied to coronal conditions and the dynamic spectra of the radio emission excited by the shock are synthesized, reproducing metric and kilometric type II bursts. The features corresponding to the metric type II burst precursor and the moving type IV burst in the case of kilometric type II bursts are identified. A specific radio signature that is sometimes observed at the onset of a metric type II burst is found to appear immediately before the shock wave formation due to the associated growth of the magnetic field gradient. Time delays and starting frequencies of bursts' onsets are calculated and presented as a function of the impulsiveness of the source-region expansion, using different values of the ambient Alfvén velocity and various time profiles of the expansion velocity. The results are confronted with the observations of metric and kilometric type II solar radio bursts. 相似文献
83.
An interval-parameter multi-stage stochastic programming model for water resources management under uncertainty 总被引:1,自引:0,他引:1
In this study, an interval-parameter multi-stage stochastic linear programming (IMSLP) method has been developed for water resources decision making under uncertainty. The IMSLP is a hybrid methodology of inexact optimization and multi-stage stochastic programming. It has three major advantages in comparison to the other optimization techniques. Firstly, it extends upon the existing multi-stage stochastic programming method by allowing uncertainties expressed as probability density functions and discrete intervals to be effectively incorporated within the optimization framework. Secondly, penalties are exercised with recourse against any infeasibility, which permits in-depth analyses of various policy scenarios that are associated with different levels of economic consequences when the promised water-allocation targets are violated. Thirdly, it cannot only handle uncertainties through constructing a set of scenarios that is representative for the universe of possible outcomes, but also reflect dynamic features of the system conditions through transactions at discrete points in time over the planning horizon. The developed IMSLP method is applied to a hypothetical case study of water resources management. The results are helpful for water resources managers in not only making decisions of water allocation but also gaining insight into the tradeoffs between environmental and economic objectives. 相似文献
84.
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86.
Summary The three-dimensional mesoscale cloud-resolving model ARPS (Advanced Regional Prediction System) was used to investigate the
dispersal of an inert seeding agent within a cumulonimbus (Cb) cloud developing from two different initial states. In this
paper, we stress the influence vortices in the cloud have on seeding agent dispersion. If a strong directional ambient wind
shear is present in the lowest layer, a vortex pair formed at the flanks of the simulated cloud. Following the velocity field,
a considerable amount of the injected seeding agent would be thrown out to the rear of the cloud, where both updrafts associated
with vortices and downdrafts occurred. After a short time the agent was present only in the cloud periphery. If the Cb cloud
developed under conditions where directional ambient wind shear did not exist, seeding agent dispersion would be quite different.
In this case, almost all the seeding agent was transported into the main updraft, while the residence time of the agent within
the cloud was longer due to the weaker cloud dynamics. Therefore, we must pay attention to whether or not the cloud contains
vortices when we make the decision where to seed. This is necessary in order to minimize the loss of seeding material. 相似文献
87.
K. Pandžić I. Šimunić F. Tomić S. Husnjak T. Likso D. Petošić 《Theoretical and Applied Climatology》2006,85(1-2):107-115
Summary This paper presents an the evaluation of three mathematical models for the estimation of 10-day drain discharge using weather, pedological and phenological parameters. One model uses modified Palmer’s procedure for the calculation of
water balance components and the second two use empirical multiple linear regression. The models have been applied to data
of an amelioration experimental field in central Croatia (south-western part of the Pannonian Lowland), where a set of average
10-day air temperature and relative humidity data, average wind speed, cumulative precipitation and drain discharge amounts,
insolation and soil moisture data and vegetation indices have been collected. The experiment has been performed during the
period 1990–1992. The models have been tested by comparing estimated and observed 10-day drain discharge amounts. All models
mainly give acceptable cumulative results although their accuracy depends on the season. 相似文献
88.
地球化学块体与大型矿集区的关系——以东天山为例 总被引:11,自引:5,他引:11
通过在东天山15万km2的战略性深穿透地球化学调查共圈出大于1000km2以上的地球化学块体18处,其中铜-铅-锌-银地球化学块体5处,铜地球化学块体3处,铜-镍地球化学块体1处,金的地球化学块体4处,铀的地球化学块体3处,铂-钯地球化学块体1处,钨地球化学块体1处。有6处地球化学块体与已知矿集区相对应,新圈定的地球化学块体12处,其中有3处发现了新的矿床。根据这些块体与矿集区的对比得出如下结论:所有的已知矿集区都位于地球化学块体的范围之内,地球化学块体为矿集区的形成提供了丰富的物质基础;有矿集区的存在一定有地球化学块体的存在,但反过来有地球化学块体的存在不一定有矿集区的存在,地球化学块体是客观存在的,而矿集区是已经发现了一系列矿床并勘探到一定程度才能称作矿集区,因此,地球化学块体内可能会存在潜在的矿集区,这为利用地球化学块体预测新的矿集区提供了依据。 相似文献
89.
针对三维激光测高拟合问题,本文采用BP神经网络进行拟合,该方法可以有效地消除或减弱数据中的系统误差影响,提高计算精度。实际算例证明,在数据无粗差情况下,BP神经网络的内符合与外符合精度优于传统的二次曲面拟合的精度。 相似文献
90.
针对传统BP神经网络容易发散、泛化能力差等问题,采用自适应Kalman滤波方法训练神经网络的连接权。与Kalman滤波训练连接权和传统的BP算法相比,该方法提高了BP神经网络计算精度,增强了泛化能力。实测数据的计算结果证明了该方法的可行性与有效性。 相似文献