Variation of permeability with depth and lithology in a formation of fractured sandstone-mudstone media          下载免费PDF全文

JIANG Xiao-wei  WAN Li  Bill X.HU 《水科学进展》2008,19(4)

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数字地质调查系统在西藏驱龙矿区资源量 估算中的应用     

徐开锋  刘鸿飞  蒋光武  王平 《地质通报》2008,27(7):1011-1018

埋藏于地下的矿产资源形态千差万别,产状复杂多变,数据来源多种多样。如何科学、合理、准确、灵活、高效地估算在一定工程控制条件下的资源量,完成资源量估算的各类图件、报表制作满足不同工作的需求是目前急需解决的问题。将数字地质调查系统技术运用到资源量估算领域是解决问题的有效途径。数字地质调查系统是基于GIS技术并在计算机软硬件支持下,融合计算机图形学、计算机人工智能和数据库技术于一体,实现对多源、海量地学实体数据采集、管理、存储、处理、成图、分析、成果输出等全过程的数据表达,实现了从野外工作到成果汇交的全数字化过程的无缝连接。通过在驱龙矿区的应用,充分体现了系统对多源、海量地学数据进行科学、合理、准确、灵活、高效的处理能力。  相似文献   

长江水系河水主要离子化学特征   总被引：14，自引：2，他引：12  

夏学齐  杨忠芳  王亚平  季峻峰  李文明  袁旭音 《地学前缘》2008,15(5):194

2007年夏季采集了长江从上游沱沱河至入海口的干流原水样品36个,长江各主要支流水样品40个,分析了江水Ca2+、Mg2+、Na+、K+、HCO3-、SO42-、Cl-离子含量及溶解性SiO2等溶质成分。结果显示,长江流域水系离子化学组成主要受碳酸盐和蒸发岩风化控制,长江上游水离子化学呈现阳离子以K+和Na+为主,阴离子以Cl-和SO42-为主的蒸发岩类风化控制特征,但随着采样点位下移,离子含量逐渐呈现阳离子以Ca2+为主,阴离子以HCO3-为主的逐渐向碳酸盐风化过渡的特征;从时间变化上看,与20世纪50年代至1990年长江水离子化学数据相比,以Na+、K+、SO42-和Cl-为代表的所有阴阳离子均有明显增加;从通量上看,洞庭湖和鄱阳湖是长江离子两个最大的输入源,除洞庭湖和鄱阳湖外的其他长江各大支流中,岷江是长江Na+、K+、Ca2+、Mg2+、F-和HCO3-的最大输入源,嘉陵江是SO24-和溶解性SiO2的最大输入源;在几大世界河流中,长江是对海洋Mg2+、SO24-和Cl-的输入通量最大的河流,Ca2+和HCO3-通量仅次于亚马逊河。  相似文献   

Influence of dissolved oxygen concentration and aeration time on nitrite accumulation in partial nitrification process   总被引：1，自引：1，他引：0  

X. Guo Ph. D.  J. H. Kim Ph.D.  S. K. Behera Ph.D.  H. S. Park Ph.D. 《International Journal of Environmental Science and Technology》2008,5(4):527-534

This study investigated the influence of dissolved oxygen concentration and aeration time on nitrification and nitrite accumulation in an attempt to optimize the recently developed biological-partial-nitritation process for the treatment of strong nitrogen wastewaters. Investigation of dissolved oxygen concentration on ammonium and nitrite oxidation was carried out in a batch reactor. The dissolved oxygen concentration of 0.5 mg O₂/L inhibited both ammonium as well as nitrite oxidation, while increase of dissolved oxygen concentration to ～1 mg O₂/L increased the ammonium oxidation rate and was comparable to that at higher dissolved oxygen concentrations. Experiments were carried out in a sequencing batch reactor for more than 100 days to investigate the influence of aeration time on nitrite accumulation. The dissolved oxygen concentration was controlled at ～1.0 mg O₂/L (in the range of 0.8–1.5 mg/L) during the aeration stage, and volatile suspended solid was maintained at 2.0 g/L while temperature and pH were 30±1°C and 8.3±0.1, respectively. In a typical cycle, complete nitrification occurred at aeration time longer than 6 h. When the aeration time was reduced to 4 h., ～80 % of partial nitritation was achieved. With a further reduction in aeration time to 3 h., nearly 1:1 nitrite/ammonium ratio was yielded. This result revealed that for the reactor design, aeration time determined by feasibility experiments must be considered based on the nitrogen strength in wastewater and biomass concentration in the reactor with dissolved oxygen concentration of ～1.0 mg O₂/L for satisfactory partial nitrification with subsequent processes such as anaerobic ammonium oxidation.  相似文献   

Ecological studies on the Kerhni reservoir (N-Greece)     

A. Kamarianos Dr.  X. Karamanlis Dr.  S. Dellis  S. Kilikidis Dr.  Th. Kousouris  G. Foties 《GeoJournal》1992,28(1):73-80

This paper refers to the morphometric and hydrological conditions, as well as to the physical and chemical characteristics of the Kerkini reservoir (N Greece) and determines the trophic status. The flushing rate, and the residence time of the water show clearly the dominance of the riverine system upon the lacustrine circulation pattern. The shallowness of the reservoir, the inflow of river Strimon, and the nearly continuous functioning of the dam throughout the year should be considered as the factors influencing the circulation of the water in the reservoir. Phosphorous mean annual value, mean annual and maximum values of chlorophyll-a were found 106.6 g P 1^–1, 18.4 g 1^–1, 29.7 g 1^–1 respectively. There is a tendency of the reservoir to decline into a hypertrophic state from a eutrophic one. River Strimon contributes significantly to the overloading of the reservoir by nitrogenous agricultural effluents.  相似文献   

Pitch angle scattering of solar particles: Comparison of ‘particle’ and ‘field’ approach     

J. F. Valdés-Galicia  G. Wibberenz  J. J. Quenby  X. Moussas  G. Green  F. M. Neubauer 《Solar physics》1988,117(1):135-156

In the quasi-linear theory of pitch angle scattering the power spectrum of magnetic field fluctuations is related to the shape of the pitch angle diffusion coefficient D(), the absolute value of the mean free path , and the rigidity dependence of the mean free path (R). We discuss these relations in detail during the solar particle event of 11 April, 1978 which was observed on HELIOS-2 at a distance of 0.49 AU from the Sun. Magnetic field measurements obtained during the time of the event are used as a basis for the layer model in which the method of particle trajectories in an actually measured field is used to simulate pitch angle diffusion. The values of D() and based on the trajectory simulation for 100 MeV protons (field approach) are compared with results obtained from solar proton data (particle approach) and with predictions from quasi-linear theory based on the additional assumption of the slab model for magnetic field fluctuations (QLT approach). The time of the event is characterized by a high level of field fluctuations, the observed mean free path of about 0.03 AU for 100 MeV protons is smaller than the average value near 1 AU. Results from the field and particle approaches agree surprisingly well. The remaining difference in the mean free path of about a factor of 2 could be due to tangential discontinuities which are measured by the magnetometer, but not seen by the real particles traveling along the average field. The results from the field and QLT approaches based on the same set of magnetic field measurements differ by about a factor of 4. One of the reasons for this discrepancy is that the conditions for resonance scattering are only marginally valid. In addition, the wave vectors representing Alfvén-type fluctuations may not be totally field aligned. This deviation from the slab model would cause an increase of the theoretically predicted mean free path and lead to better agreement with the other two approaches.  相似文献   

Long-term orbit computations with KS uniformly regular canonical elements with oblateness     

Ram Krishan Sharma  M. X. James Raj 《Earth, Moon, and Planets》1988,42(2):163-178

This paper concerns with the study of KS uniformly regular canonical elements with Earth's oblateness. These elements, ten in number, are all constant in the unperturbed motion and even in the perturbed motion, the substitution is straightforward and elementary due to the transformation laws being explicit and closed expression. By utilizing the recursion formulas of Legendre's polynomials, we are able to include any number of Earth's zonal harmonics J _n in the package and also economize the computations. A fixed step-size fourth-order Runge-Kutta-Gill method is employed for numerical integration of the canonical equations.Utilizing 5 test cases covering a large range of semimajor axis and eccentricity, we have carried out computations to study the effects of Earth's zonal harmonics (up to J ₃₆) and integration step-size variation. Bilinear relations and energy equation are used for checking the accuracies of numerical integration. From the application point of view, the package is utilized to study the behaviour of 900 km height near-circular sun-synchronous satellite orbit over a longer duration of 220 days time (nearly 3078 revolutions) and the necessity of including more number of Earth's zonal harmonic terms is noticed. The package is also used to study the effect of higher zonal harmonics on three 900 km height near-circular orbits with inclinations of 60, 63.2, and 65 degrees, by including Earth's zonal harmonics up to J ₂₄. The mean eccentricity (e _m) is found to have long-periods of 459.6, 6925.1 and 1077.6 days, respectively. Sharp changes in the variation of _m near the minima to e_m are noticed. The values of _m are found to be very near to +-90 degrees at the extrema of e_m. The same orbit is employed to study the effect of variation of inclination from 0 to 180 degrees on long-period (T) of eccentricity with J ₂ to J ₂₄ terms. T is found to increase rapidly as we proceed towards the critical inclinations.  相似文献   

Analysis of 11 late-type close binary systems     

K. C. Leung  D. S. Zhai  R. X. Zhang  Q. Y. Liu  J. T. Zhang  Y. L. Yang 《Astrophysics and Space Science》1984,99(1-2):411-411

This is a preliminary report on the joint research project between 3 observatories: Beijing, Yunnan, and Behlen Observatories from China and the United States. The systems we have been dealing with are primary of late spectral types and with short periods. Most of the observations were secured from the observatories in China. The computational analysis is carried out in University of Nebraska, Lincoln. The photometric solutions are based on the Wilson and Devinney method. Out of 11 systems analyzed 6 of them: AO Cam, ER Ori. BX Peg, BB Peg, U Peg, and SW Lac are found to be contact systems. All of them are having their primary eclipses at occultation. Therefore they can be classified as W-type W U Ma systems. They also show other W-type characteristics.Three systems: ZZ Aur, RZ Dra, and AX Vir are found to be semi-detached systems, with low mass components filling their Roche surfaces. The massive components are having their radii fairly close to Roche surfaces and are larger than their contact companions.The last two systems: AT Cam and AZ Cam are found to be detached systems, but with their low mass components almost filling their Roche surfaces. This type of configuration is of great interest to our understanding of close binary evolution. We believe that these systems are at phase immediately after the normal Algol phase, where the mass lossing components detached from the Roche surfaces at the conclusion active mass lost phase.Paper presented at the Lembang-Bamberg IAU Colloquium No. 80 on Double Stars: Physical Properties and Generic Relations, held at Bandung, Indonesia, 3–7 June, 1983.  相似文献   

Perceived and projected flood risk and adaptation in coastal Southeast Queensland,Australia     

Morena Mills  Konar Mutafoglu  Vanessa M. Adams  Carla Archibald  Justine Bell  Javier X. Leon 《Climatic change》2016,136(3-4):523-537

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Study of Seabed Pullout Resistance on a Quadrate Foundation Using Adaptive Time-Stepping Method     

X. W. Zhang  R. Uzuoka  Q. Shao 《Marine Georesources & Geotechnology》2016,34(3):234-243

We developed a solid-fluid analysis procedure that can simulate the seabed pullout resistance based on two adaptive time-stepping methods. One is heuristic time stepping, and the other is based on the truncation error estimation in temporal discretization. The pullout resistance is investigated through experiments and numerical simulations. The results show that the proposed adaptive stepping methods can deal with the un-convergence problems caused by the time increment and can improve the calculation efficiency. The base suction, related to the area of the negative pore water pressure, is generated under the structure and provides the pullout resistance.  相似文献