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301.
Jia Zhenyuan 《地球科学》1990,(1)
作者以鄂尔多斯地区奥陶系丰富的重力流沉积为例,借助非牛顿流体力学的基本原理,对重力流运动的特点和类型作了进一步的探讨,重力流运动的特点是:具层移(流)运动、有旋性、挤压性、涡旋性、惯性、颗粒上浮性、颗粒下沉、颗粒碰撞、剪切作用和下切作用。重力流可分为:滑动流、混合流、碎石(屑)流、颗粒流、液化流和浊流。 相似文献
302.
Roberto Ragazzoni 《Experimental Astronomy》1997,7(3):209-219
Relativistic aberration and Doppler effects on rotating mirrors have been claimed (Ragazzoni & Claudi, 1995) and later refuted (Hickson, Bhatia & Iovino, 1995). While an experimental confirmation of the absence of the Doppler effect has been carried out in 1974, a measurement of the absence of the aberration effect is missing. It is shown that analyzing published data on the LAGEOS pulse-return signature an experimental confirmation of the absence of the effect is obtained. 相似文献
303.
超声辅助方法是制备纳米材料的有效手段,可提高纳米材料的磁学、光学等特殊性能。本文在不同p H条件下超声辅助合成GdPO_4:Ce,Tb三元体系荧光粉,采用X射线粉末衍射、傅里叶变换红外光谱、扫描电镜、透射电子显微镜及光致发光荧光光谱分析方法对样品进行了表征。结果表明:①样品仅在p H=1时,才能生成规则的15 nm×104nm六方晶系纳米棒状正磷酸盐绿色荧光粉,晶体优先选择(102)及(200)晶面生长;p H1无法得到样品;p H1为颗粒状的正磷酸盐绿色荧光粉。②进一步验证了Gd、Ce、Tb三元体系中Ce~(3+)离子能量较高的5d组态将能量传递给Gd~(3+)离子,而Gd~(3+)离子的跃迁发射与Tb~(3+)离子的吸收峰有较大的光谱重叠,故传递途径是Ce~(3+)→Gd~(3+)→Tb~(3+);少量Ce~(3+)的引入可提高以GdPO_4基质发光材料的发光强度。此结果可为开发稀土材料提供理论依据。 相似文献
304.
The Southern Ocean is a strong sink for atmospheric CO2, making it especially vulnerable to ocean acidification (OA). The aragonite saturation state (Ωarg) of seawater has been used as an index for the estimation of OA, which plays a critical role in evaluating the living environment of marine calcified organisms. However, it is very difficult to perform the studies of OA and Ωarg in the Southern Ocean due to its harsh climate. Therefore, in order to better understand the OA and its further influences, the advances of Ωarg studies were summarized in the oceans surrounding the Antarctica. Significant spatial and temporal variations of surface seawater Ωarg are demonstrated in the Southern Ocean. In general, the surface seawater Ωarg shows a lower value in the off-shore areas than in the open oceans. And, Ωarg also exhibits a strong seasonal cycle with a higher value in summer than in winter. The distributions of Ωarg in vertical water column generally present a declining tendency from surface to bottom. In addition, the shoaling of Ωarg horizon at high latitude could be attributed to the ventilation and upwelling of deep waters in the Southern Ocean. There are many factors that could impact the Ωarg in the Southern Ocean, including sea ice melting, sea-air CO2 exchange, biological activities and hydrological processes, etc. Finally, the future changes and key scientific problems of OA in the Southern Ocean are proposed. 相似文献
305.
306.
海洋酸化是全球变化的一个关注点,南大洋CO2吸收量占海洋对人为CO2的吸收量的30%—40%,同时,南大洋是缓冲能力较低、生态系统脆弱的高纬海域,所以,理解南大洋海水酸化过程及其控制因素就显得尤为重要。海水酸化引起海水中碳酸根离子(CO2-3)的浓度、碳酸钙饱和度(Ω)降低,这对成钙类生物碳酸钙(包括文石和方解石)的形成有害,最终可能对生态系统造成危害。了解海洋酸化的影响、预测酸化对海水碳酸盐体系和生态系统的影响具有重要意义。因此,本文对目前南大洋的开阔大洋区以及两个具有代表性的边缘海和海湾的酸化研究概况进行了梳理,试图对南大洋表层海水酸化的研究进行概述、展望未来南大洋海洋酸化研究趋势并提出一些亟须解决的问题。 相似文献
307.
Mao Fangguan Lu Shunchang Luo Ruiren
Senior Engineer Naval Medical Research Institute P. L. A. of China Shanghai Senior Engineer Navigation Guarantee 《中国海洋工程》1995,(4)
The Diver Gas Recovery Installation (DGRI) was evaluated at 80 msw saturation - 100 msw excursion diving on HeO2 in the Naval Medical Research Institute (NMRI) of China in April, 1995. The diving depth, lockout time, breathing gas flow rate and consumption, inspired oxygen partial pressure (PO2) and carbon dioxide partial pressure (PCO2) were monitored. The results indicated that PO2 was controlled to fluctuate from 64.3 to 84.0 kPa and PCO2 went up from 0.01 kPa up to O.I kPa during 4 hours excursion diving; recovery of breathing gas reached 95%; three divers felt well and breathed comfortably during simulating heavy work. The test showed that it met desired performance goals. The DGRI is a kind of important equipment for long duration deep dive. It enables the gases exhaled by the divers to be re-cycled, and therefore it has great social, military and economic significance for diving operation and submarine rescue. 相似文献
308.
Zhenfeng Qiu Junjie Wang Yulong Chen Yang Yang Yongsuo Li 《Marine Georesources & Geotechnology》2020,38(7):867-875
AbstractSandstone-mudstone particle mixture (SMPM) is one of the main materials, which has been widely used for filling in and around reservoirs for water conservation projects. During the periodic rising and falling of the water level, the fill material for the embankments, dam, and other waterfront features will also undergo drainage-saturation cycles. The deformation and coefficient of lateral pressure at rest K0 may be affected by periodic saturation. In this study, a device is modified for testing the K0 for gravel-soil under periodic saturation. In order to investigate the effects of periodic saturation on K0, a series of experiments were performed for SMPM under different vertical stress and saturation cycling. K0N values of SMPM containing 20% mudstone particles under periodic saturation were obtained. The results shows that the K0N initially increased, but eventually reached a stable value with the increasing number of periodic saturation cycles. The magnitude of the coefficient increment was also found to be related to the stress condition. K0N is a logarithmic function of the saturation cycling time. By calculating K0N with the proposed empirical formula, the deformation and stress distribution of the SMPM filler in waterfront engineering works can be calculated with greater precision. 相似文献
309.
It has been well documented that natural marine Ariake clays are sensitive clays. In this study, extensive data of marine Ariake clays are obtained to investigate the gravitational compression behavior for sensitive clays. Analysis results indicate that the compression behavior of remolded Ariake clays is not different from that of other remolded/reconstituted soils. But natural Ariake clays do not follow the gravitational compression pattern reported by Skempton (1970) for natural sedimentary soils. At a given value of effective overburden pressure, the void ratios of natural Ariake clays are almost independent of liquid limits. Most natural Ariake clays lie above the sedimentation compression line proposed by Burland (1990). When the liquid limit is larger than 90% and the ratio of natural water content over liquid limit ranges 0.8-1.1, the natural Ariake clays lie around the sedimentation compression line. In addition, the natural Ariake clay with higher value of the ratio of natural water content over liquid limit lies above the natural Ariake clay with lower value of the ratio of natural water content over liquid limit. Salt removal is the most probable cause for such a phenomenon. 相似文献
310.
In this paper, the control performance is investigated of Circular Tuned Liquid Column Dampers (CTLCD) over torsional response of offshore platform structures excited by ground motions. Based on the equation of motion for the CTLCD-structure system, the optimal control parameters of CTLCD are given through some derivations on the supposition that the ground motion is a stochastic process. The influence of systematic parameters on the equivalent damping ratio of the structures is analyzed with purely torsional vibration and translational-torsional coupled vibration, respectively, The results show that the Circular Tuned Liquid Column Damper (CTLCD) is an effective torsional response control device. 相似文献