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211.
Francis T.C. Ting 《Organic Geochemistry》1984,5(4):279-281
Use of the attitude of the optical axis of vitrinite as an indicator of paragenetic relationship of thermal maturation/coalification and tectonics is discussed. A constant angular relationship between the optical axis and bedding plane of coals is observed in seven coal mines in the Canadian Rocky Mountain coal fields. This constant relationship suggests that thermal maturation predated tectonic structures. 相似文献
212.
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Channel morphology and its impact on flood passage, the Tianjiazhen reach of the middle Yangtze River 总被引:1,自引:0,他引:1
The Tianjiazhen reach of the middle Yangtze is about 8 km long, and characterized by a narrow river width of 650 m and local water depth of > 90 m in deep inner troughs, of which about 60 m is below the mean sea level. The troughs in the channel of such a large river are associated with regional tectonics and local lithology. The channel configuration plays a critical role in modifying the height and duration of river floods and erosion of the riverbed. The formation of the troughs in the bed of the Yangtze is considered to be controlled by sets of NW–SE-oriented neotectonic fault zones, in which some segments consist of highly folded thick Triassic limestone crossed by the Yangtze River. Several limestone hills, currently located next to the river channel, serve as nodes that create large vortices in the river, thereby accelerating downcutting on the riverbed composed of limestone highly susceptible to physical corrosion and chemical dissolution. Hydrological records indicate that the nodal hills and channel configuration at Tianjiazhen do not impact on normal flow discharges but discharges > 50,000 m3s− 1 are slowed down for 2–3 days. Catastrophic floods are held up for even longer periods. These inevitably result in elevated flood stages upstream of prolonged duration, affecting large cities such as Wuhan and a very large number of people. 相似文献
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体验经济赋予了民族文化旅游产品新的内涵,也促使民族文化旅游产品的体验化设计成为必然.民族文化旅游产品体验化设计应遵循产品独特性、体验主题化、高度参与性、文化真实性的原则,从体验主题的确定、体验氛围营造、体验活动的策划、体验线路的安排和旅游纪念品的设计等5个方面进行. 相似文献
217.
Land subsidence basically is the deprivation of water and earth resources, further inducing social and economical undesirable
impact. The principal direction of land subsidence prevention is properly management of groundwater. However groundwater management
should be developed on the basis of combined technical, economical, social and institutional approaches to management that
reflect local conditions and can be adapted and evolved. Therefore, the aim of this paper is to make land subsidence prevention
strategies for government to refer. Before year 1969, agriculture was the main land utilization business in Pingtung Plain.
Due to intensive development of fish breeding after 1970’s, the aquaculture area along the estuary region of Pingtung Plain
have been dramatically increased. Groundwater thus became the main fresh water resource for aquacultural water diluting and
flushing because of the insufficiency in surface water supply. The uncontrolled development of groundwater resources has led
to undesirable effects, especially in the south where aquaculture is concentrated. These effects are land subsidence, saline
water intrusion, lowering of water tables and reductions in well yields. Government stressed on the improvement of breeding
technology in the past, which mainly focused on the water quality control in order to raise the culture density, however,
it neglected the impact to the environment and quantity control. This paper promotes a reasonable aquacultural water consumption
policy aims at finding out the most suitable breeding species considering water consumption and its reasonable breeding area
under the premise that it will not depress the original profit of aquatic products trading.
Published in Russian in Vodnye Resursy, 2007, published in Vodnye Resursy, 2007, Vol. 34, No. 3, pp. 281–289.
The text was submitted by the authors in English. 相似文献
218.
基于进化方向遗传算法的四维变分资料同化方法 总被引:7,自引:5,他引:7
数值天气预报模式初始时刻要素场的变分同化问题是一个非线性最优化问题。利用进化方向遗传算法(EDGA)求解该最优化问题,并对理想初始场作数值模拟,结果表明模拟的效果较好。 相似文献
219.
使用共轭码技术,构造了中尺度模式的伴随模式,研究了模式侧边界条件。基于伴随模式技术的原理,设计了伴随同化和Derber同化方法两套方案;下降算法采用共轭梯度法,使用准真实资料,进行子同化数值试验和预报试验。结果表明,两套同化方案都取得了一定的同化效果,Derber同化方法比伴随同化更令人满意。证明了变分同化是提高预报准确率的一种非常有效的手段。 相似文献
220.
提出了一种符合空间认知规律的栅格化处理的任意多边形间方向关系的计算方法,该方法计算结果与人眼的判断结果非常接近,在此基础上讨论了多边形间方向关系的可确定问题,并提出了一种基于8方向隶属零值个数的两个多边形方向关系可确定程度的判定方法。 相似文献