填砾厚度与单井出水量及井水泥沙含量关系探讨     

李清平  王桂玲 《山东国土资源》1999,(2)

山东黄泛平原区浅层地下水丰富，但由于含水层岩性以粉砂为主，单井出水量小，井水含泥沙量高，井易淤易堵，因而影响该层地下水的开发利用。通过对填砾厚度与单井出水量及井水泥沙含量试验资料的分析，得出适宜细颗粒地层分布区成井的最佳填砾厚度为１５０～２００ｍｍ。这一结论对该类地区浅层地下水开发利用具有指导意义  相似文献   

Forecast of China’s grain production development and its self-support rate analysis     

Xikang Chen  Haijian Wang  Ju’e Guo 《中国地理科学(英文版)》1997,7(2):97-105

This paper discuses four stern difficulties and challenges faced by the development of grain production in China. According to the basic national conditions of China and the amount of grain resources in the world market, China must meet the grain demands mainly by her own domestic production. Using the input-occupancy-output techniques and system science methods, this paper makes a forecast about China’s grain output, grain import and self-support rate in the year 2030. The research was supported by the National Natural Science Foundation of China.  相似文献   

A constitutive model for granular materials with grain crushing and its application to a pyroclastic soil     

Manuela Cecconi  Antonio DeSimone  Claudio Tamagnini  Giulia M.B. Viggiani 《国际地质力学数值与分析法杂志》2002,26(15):1531-1560

A constitutive model for granular materials is developed within the framework of strain–hardening elastoplasticity, aiming at describing some of the macroscopic effects of the degradation processes associated with grain crushing. The central assumption of the paper is that, upon loading, the frictional properties of the material are modified as a consequence of the changes in grain size distribution. The effects of these irreversible microscopic processes are described macroscopically as accumulated plastic strain. Plastic strain drives the evolution of internal variables which model phenomenologically the changes of mechanical properties induced by grain crushing by controlling the geometry of the yield locus and the direction of plastic flow. An application of the model to Pozzolana Nera is presented. The stress–dilatancy relationship observed for this material is used as a guidance for the formulation of hardening laws. One of the salient features of the proposed model is its capability of reproducing the stress–dilatancy behaviour observed in Pozzolana Nera, for which the minimum value of dilatancy always follows the maximum stress ratio experienced by the material. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Forms of phosphorus and silicon in the natural grain size surface sediments of the southern Bohai Sea   总被引：5，自引：0，他引：5  

宋金明  罗延馨  吕晓霞  李鹏程 《中国海洋湖沼学报》2003,21(3):286-292

The forms of phosphorus and silicon in the natural grain sizes surface sediments of the southern Bohai Sea were studied. In sediments, the organic matter bound form of phosphorus was the main form of transferable phosphorus and ranged from 0.37μmol/g to 1.57μmol/g, accountingfor 10.7% of the total phosphorus, others were the carbonate bound form, iron-manganeso oxide bound form and ion-exchange able form; the transferable form of phosphorus accounted for 19.2% of the total phosphorus. Silicon‘ s carbonate bound form was predominant over others among its transferable forms, and content ranged from 1.55μmol/g to 8.94μmol/g, accounting for 0.05% of the total silicon; the total amount of transferable silicon forms accounted for only 0.12% of the total silicon. Therefore, 19.2% of the total phosphorus and 0.12 % of the total silicon contained in the surface sediments of the southern Bohai Sea could participate in the biogeochemical cycling.  相似文献   

A contrast analysis on the load character of the Changjiang River and the Huanghe River     

Wang Lachun  Zhang Jianxin  Chen Xiaoling  Chu Tongqing 《中国地理科学(英文版)》1997,8(4):317-325

According to the analysis of grain size, mineral composition and inclusion in quartz grain of the suspended and bed load sampled from the Changjiang (Yangtze) River and the Huanghe (Yellow) River, the authors reveal the differentiation of loads between the two rivers. In the Huanghe River the size of suspended load is coarser than that in the Changjiang River, while the bed load is on the contrary. Through heavy mineral analysis, the biotite content of the Huanghe River loads is much higher than that of the Changjiang River, and the monomorillonite content of the former is about two times higher than the latter. All those may be attributed to the effects of different material sources and hydraulic conditions on load. The analysis of inclusion in quartz grain definitely illustrates the environmental difference of material sources between the two rivers. In the meantime, it provides a new method in seeking source of river load. Subsidized by the National Natural Science Foundation. This paper is attributed to careful guidance from Prof. Wang Ying & Prof. Shi Yunliang.  相似文献   

Active hot star shells     

Philippe Stee 《Astrophysics and Space Science》2003,286(1-2):225-236

Interferometry in the visible provides milliarcsecond spatial resolution and thus has been used for studying the circumstellar environment of active hot stars. In this paper I will illustrate how the visibility modulus and phase can be used to better constrain the physics of Be disks through results from the VLA, the MkII and the GI2T interferometers. I will insist on the importance and the potential of coupling high angular resolution with high spectral resolution to the study of Be shells. Finally I will present a possible study of the circumstellar disk of Be stars using the VLTI. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

积分第二中值定理“中值点”渐近性探讨     

胡洪萍 《地球科学与环境学报》1997,(Z1)

本文研究了积分第二中值定理“中值点”的渐近性，得出了一般性的结果。  相似文献   

Densification and grain coarsening of melting snow     

周石硚  中尾正义  桥本重将  坂井亚规子  成田英器  石川信敬 《极地研究(英文版)》2003,14(1)

1　IntroductionSnowdensificationiscriticalforcalculationsinengineering glaciology,snowavalancheforecasting ,springflooding,andotherpracticalaspects.Itisalsoimportantforinterpretingicecoredataincludingthosetakenfromratherwarmsiteswheresurfacelay ersexperiencemelting ,sinceitwouldaffectthechangeofannuallayerthicknesswithtime.Whileextensivestudies(e.g .AndersonandBenson 1 963 ;Bader1 960 ,1 962 ;Koji ma 1 95 4,1 95 5 ,1 95 6,1 95 7,1 95 8,1 95 9,1 964;Keeler 1 967;Gow 1 975 ;MaenoandE binuma 1…  相似文献   

Capture of grains into resonances through Poynting-Robertson drag     

B. Sicardy  C. Beaugé  S. Ferraz-Mello  D. Lazzaro  F. Roques 《Celestial Mechanics and Dynamical Astronomy》1993,57(1-2):373-390

We review here some relevant problems connected to the evolution of circumstellar dust grains, subjected to Poynting-Robertson (PR) drag, and perturbed by first-order resonances with a planet on a circular orbit. We show that only outer mean motion resonances are able to counteract the damping effect of PR drag. However, the high orbital eccentricities reached by the particle lead to orbit crossings with the planet. This is a serious difficulty for a permanent trapping to be achieved. In any case, we show that the time spent in the resonance is long enough for statistical effects (accumulation at the resonant radius) to be significant. We underline some difficulties associated with this problem, namely, the non-adiabaticity of motion in the resonance phase space and the existence of close encounters with the planet at high eccentricities.  相似文献   

静力触探在莱州湾冰后期三角洲层序地层学研究中的应用     

徐建国  刘中业  陶有兵  徐华  纪汶龙  张春池 《地球学报》2022,43(1):11-24

静力触探试验是广泛应用于海岸带地区岩土工程勘察的原位测试手段,静探数据的连续性、高分辨率在其应用于晚第四纪地层结构研究中具有独特的优势.本文对莱州湾沿岸249个工程地质孔-静力触探孔组的岩性编录资料与静探参数资料进行对比研究,建立了冰后期沉积不同沉积相的静探参数曲线识别模式,以此为基础配合14C测年、微体古生物鉴定等资...  相似文献