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排序方式: 共有802条查询结果,搜索用时 343 毫秒
91.
SADIKI Moulay Lhassan EL MANSOURI Bouabid BENSEDDIK Badr CHAO Jamal KILI Malika EL MEZOUARY Lhoussaine 《地下水科学与工程》2014,7(3):224-236
In arid and semi-arid zones, water is the most vulnerable resource to climate change. In fact, various techniques such as artificial recharge are adopted to restore aquifers and to ensure aquifer sustainability in relation to the accelerated pace of exploitation. Morocco is a Mediterranean country highly vulnerable to climate change, many of its main aquifers are subjected to excessive drawdowns. This technique is practiced to increase potentiality of these aquifers. In the Northwestern area of Morocco, the significant development experienced by Tangier City in the industrial, tourism, and commercial sectors will lead to increased water requirements-up to 5 067 L/s (159.8 mm3) by 2030. However, the Charf El Akab aquifer system, subject to artificial recharge, is the only groundwater resource of Tangier region; hence, a rational management context is needed to ensure aquifer sustainability, and optimized exploitation under the background of differing constraints, such as increased water requirements, and climate change impacts. This work aims to respond, for the first time, to the Charf El Akab aquifer overexploitation problem, and to evaluate the future scenarios of its exploitation in the event of failure of one of the superficial resources. This work also presents a synthesized hydrodynamic modeling based on the results of the numerical simulations carried out using Feflow software for 2004 (date of cessation of injections) and 2011 (date of resumption of these facilities), making it possible to evaluate the impact of the artificial recharge on the piezometric level of the aquifer on a spatiotemporal scale. Finally, the exploitation scenarios have shown that the aquifer of Charf El Akab will not adequatly provide for the region's water requirements on the future horizon, entailing an optimal management of water resources in the region and an intentionally increased recharge rate. 相似文献
92.
93.
从北部湾沿海采捕的日本鬼鱼由 ( Inimicus japonicus)亲鱼 ,经暂养后进行催产 ,雌鱼每千克体重注射 L RH-A3 1 0μg DOM 5mg或 HCG 60 0~ 80 0 IU LRH-A3 3 0~ 4 0μg;雄鱼注射同样药物 ,剂量减半。共采卵 1 0 9万粒 ,平均受精率 89.0 % ,平均孵化率 90 .0 % ,共培育出体长 1 .8~ 2 .3 cm的幼鱼 2 6.8万尾 ,平均成活率 3 0 .7%。 相似文献
94.
P. Exertier 《Celestial Mechanics and Dynamical Astronomy》1993,57(1-2):137-153
The monitoring of the perturbed motion of artificial satellites since the 1960's has provided a valuable resource for improved activities in geodesy. These observations and the improved geodetic techniques they fostered have provided an unparalleled means for studying both the gravity field and the Earth's shape. In this paper, we will review the various determinations of the Earth's gravity field produced at many research centers over the years from space techniques. The specific methods which have been used to measure our planet, such as satellite altimetry and satellite orbital perturbation analyses (over short and long periods of time), will be compared. 相似文献
95.
选取旱、涝、震灾害之间的一步转移概率作为B-P人工神经网络训练样本的输入信息,建立了四川旱、涝、震的人工神经网络灾型预测模型。B-P网络模型应用于实例预测结果与用主分量分析法的趋势预测结果精度接近。 相似文献
96.
Sławomir Breiter 《Celestial Mechanics and Dynamical Astronomy》1997,67(3):237-249
The analytical solution for the perturbations of an artificial satellite due to the zonal part of the geopotential is presented.
The Hamiltonian is fully normalized up to the second order by a single averaging transformation and the generating function
is given explicitly. The formulas allow an arbitrarily high degree of geopotential harmonics to be included. The transformation
from mean to osculating variables or vice versa is performed by means of a numerical method proposed by the author in a previous
paper (Breiter,1997): periodic perturbations are computed by means of a Runge-Kutta method of order 2 instead of being explicitly
derived from a generator.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
97.
1 INTRODUCTION Scientific management of aquacultural andnatural populations studies on the early life historyof flatfishes in the aspects of their metamorphosisand benthic settlement accompanying pronouncedtransitions in morphology, behavior and habitatecology have received much attention (Youson,1988). Accumulated data showed that temperatureand substrate played a main role in the recruitmentsuccess of flatfish during their early development(Rijnsdorp et al., 1995, Gibson and Robb, 2000… 相似文献
98.
地理信息系统的现状及其技术系统的研究动向 总被引:1,自引:0,他引:1
地理信息系统作为新兴的高技术系统,已经应用于整个空间信息的处理领域。本文将在分析现有系统应用水平和存在问题的基础上,着重讨论了六个方面值得重视的研究课题。 相似文献
99.
Tanveer Ferdous Saeed 《湿地科学》2012,10(2):142-148
This study investigated the effects of two alternative substrates(wood mulch and zeolite) on the performance of three laboratory-scale hybrid wetland systems that had identical system components and configurations.Each system consisted of a vertical flow(VF) wetland column,followed by a horizontal flow(HF) column and a vertical flow column.The substrates employed were wood mulch,gravel and zeolite,and Phragmites australis were planted in each column.The systems received synthetic wastewater,with pollutant loadings in the range of 8.5-38.0 g/(m2·d) total nitrogen(TN) and 4.0-46.4 g/(m2·d) biological oxygen demand(BOD5).Wood mulch and zeolite substrates showed higher efficiencies in terms of removing nitrogenous compounds and biodegradable organics.The supply of organic carbon from the organic mulch substrates enhanced denitrification,while adsorption of influent ammoniacal nitrogen(NH4-N) in zeolite played a major role in the removal of nitrogenous species in the wetland columns.Overall,the average percentage removals of TN and BOD5 reached >66% and >96% respectively,indicating stable performances by the hybrid wetland systems under the experimental loading ranges.Mathematical models were developed,based on the combination of Monod kinetics and continuously-stirred tank reactor(CSTR) flow patterns to describe the degradation of nitrogenous compounds.Predictions by the models closely matched the experimental data,indicating the validity and potential application of Monod kinetics in the modelling and design of treatment wetlands. 相似文献
100.
利用TRMM卫星资料对人工增雨云系模式云微观场预报能力的检验 总被引:6,自引:0,他引:6
文中利用TRMM卫星测雨雷达探测反演的云水、雨水、云冰和降冰4种云参数产品及实况降水资料,对比检验该人工增雨云系业务模式对云微观场和地面降水场的预报能力.结果表明,人工增雨云系模式系统对降水的预报能力要略优于现行业务运行的GRAPES模式;人工增雨云系模式系统能较好地预报云系系统云物理微观量的垂直结构特征,模式预报的微观场与卫星监测吻合较好;在播撒窗区的水平分布上,模式预报的各水凝物分布形势和强中心位置与卫星监测一致,其大小也接近监测值;人工增雨云系模式能较好地预报云的微观场和天气形势场,可作为云系人工增雨条件决策的重要参考依据. 相似文献