近场源二极激电法在贫硫银金矿床的应用效果

在管地贫硫银金矿床进行了近场源二极激电法的应用研究，获得了三高一低的次级低缓激电异常，即高ηｓ、Ｒ_２、Ｊｓ，低ρｓ，表明用次级参数表示的激电弱异常要明显，为增加矿量，提高地质找矿效果起了积极作用。     

The mean and turbulence structure simulation of the monsoon trough boundary layer using a one-dimensional model withe-l ande-ε closures

An attempt has been made here to study the sensitivity of the mean and the turbulence structure of the monsoon trough boundary layer to the choice of the constants in the dissipation equation for two stations Delhi and Calcutta, using one-dimensional atmospheric boundary layer model withe-ε turbulence closure. An analytical discussion of the problems associated with the constants of the dissipation equation is presented. It is shown here that the choice of the constants in the dissipation equation is quite crucial and the turbulence structure is very sensitive to these constants. The modification of the dissipation equation adopted by earlier studies, that is, approximating the Tke generation (due to shear and buoyancy production) in theε-equation by max (shear production, shear + buoyancy production), can be avoided by a suitable choice of the constants suggested here. The observed turbulence structure is better simulated with these constants. The turbulence structure simulation with the constants recommended by Aupoixet al (1989) (which are interactive in time) for the monsoon region is shown to be qualitatively similar to the simulation obtained with the constants suggested here, thus implying that no universal constants exist to regulate dissipation rate. Simulations of the mean structure show little sensitivity to the type of the closure parameterization betweene-l ande-ε closures. However the turbulence structure simulation withe-ε. closure is far better compared to thee-l model simulations. The model simulations of temperature profiles compare quite well with the observations whenever the boundary layer is well mixed (neutral) or unstable. However the models are not able to simulate the nocturnal boundary layer (stable) temperature profiles. Moisture profiles are simulated reasonably better. With one-dimensional models, capturing observed wind variations is not up to the mark.     

变质反应的代数识别方法

在回顾变质矿物共生组合和变质反应图解分析法的基础上，论述了录求变质矿物组合之间、同一组合内矿物之间的平衡变质反应的代数方法，即矩阵高斯变换，线性回归分析、矩阵奇值分解。     

Role of apparent cohesion in the stability of Dominician allophane soil slopes

This study examines the effect of loss of apparent cohesion from rainwater infiltration upon the stability of partly saturated, allophanic soil slopes of Dominica (West Indies). The parent material of the Dominican allophanic soils are the andesitic and dacitic volcanic rocks from ten volcanic centres of mainly Pleistocene age. Although simplifying assumptions are made to assess the depth of wetting front and magnitudes of true and apparent cohesion values of the partly saturated allophanic soils, certain inferences of practical significance emerge from the study.

Matric suction contributes to the effective stress of unsaturated soils and increases the shear strength of these soils by imparting them an apparent cohesion strength component. This apparent cohesion strength component of the partly saturated Dominician allophanic soils is considered to be related to the matric suction term (u_a−u_w) by a parabolic relationship.

The partly saturated allophanic soil slopes of Dominica would invariably fail from loss of apparent cohesion upon saturation of the soil mantle by the infiltrating water front only if (a) the average slope angle (β) is greater than or equal to the drained shear strength parameter of the unsaturated soil (Φ_d) (slopes with β ≥ Φ_d are referred to as category 1 slopes in this study) and (b) the drained cohesion parameter (c_d) belonging to the partly saturated soil of the category 1 slope is mainly contributed by matric suction induced apparent cohesion (c_app) and contribution from true cohesion (c′) is absent. However, the possibility of the category 1 slopes (for the case 1 situation) failing in the saturated condition from effective stress reduction due to rise in ground water table is shown to be an unfeasible proposition. In contrast, for the case 1 situation, the partly saturated category 2 slopes (β < Φ_d) are insusceptible to failure from reduction in effective stress due to loss of matric suction but fail in the saturated condition from effective stress reduction due to rise in ground water table. If the allophanic soils were to possess a sufficient magnitude of true cohesion (c′), even the partly saturated category 1 slopes possessing slope angles (β) much in excess of their Φ_d values (β − Φ_d = 15.1°) would remain stable upon total elimination of the matric suction induced cohesion. However, partly saturated category 1 slopes possessing a true cohesion component and insusceptible to failure from reduction in effective stress upon loss of matric suction, invariably fail in the saturated condition from reduction in effective stress due to rise in ground water table.

Using the methodology developed in this study, two previously reported case histories pertaining to rain induced translational landslides in the residual soil areas of Brazil are re-examined and the results obtained in this study are found to be in agreement with the findings of the previous researchers.     

Characteristics of VHF radiowave scintillations over a solar cycle (1983–1993) at a low-latitude station: Waltair (17.7°N, 83.3°E)

The characteristics of VHF radiowave scintillations at 244 MHz (FLEETSAT) during a complete solar cycle (1983–93) at a low-latitude station, Waltair (17.7°N, 83.3°E), are presented. The occurrence of night-time scintillations shows equinoctial maxima and summer minima in all the epochs of solar activity, and follows the solar activity. The daytime scintillation occurrence is negatively correlated with the solar activity and shows maximum occurrence during the summer months in a period of low solar activity. The occurrence of night-time scintillations is inhibited during disturbed days of high solar activity and enhanced during low solar activity.     

VICARIOUS RADIOMETRIC CALIBRATION OF SATELLITE FY-ID SENSORS AT VISIBLE AND NEAR INFRARED CHANNELS

For the problem of in-flight test site radiometric calibration for the FY-1D Meteorological Satellite onboard sensor's visible and near infrared channels,this paper described the calibration method,satellite-ground synchronous observation data acquired at China Dunhuang Calibration Test Site,parameter derivation and radiative transfer computation during the calibration,and the calibration result analysis.At FY-1D seven channels (with central wavelength at Channels 1:630 nm,2:865 nm;6:1610 nm;7:455 nm,8:505 nm;9:555 nm;10:932 nm),calibration coefficients obtained during the ground site calibration were compared with that respectively of prelaunch calibration.It is demonstrated that results of FY-1D onboard two sensors' (A and B) at channels 1,2,6 and 10 were close to pre-calibration,and the absolute difference of Gobi desert reflectance computed using test site and pre-launch calibration coefficients was no more than 2%. At other channels,large pre-launch calibration errors resulted in a poor consistency between the test site and pre-launch calibration.The errors can be corrected by the test site calibration results. Based on a rough estimation,the overall error of the calibration was about 6%. The paper also presented the in-flight vicarious calibration at the visible and near infrared channels of FY-1C sensor A which was launched in 1999 and has been put into operational mode since 2002.The results exhibit that FY-1C sensor's response has 23% attenuation at Channels 7 and 8,while only minor degradation at the other channels was found. During the mission,calibrations were also conducted at NOAA-17's Channels 1 and 2 (1:430-830 nm,2:500-1072 nm).A very good consistency has been achieved between the test site and pre-launched calibration results.     

利用敦煌辐射校正场对FY-2B静止气象卫星进行可见光通道的在轨辐射定标

FY-2B由于杂散光的影响，其可见光通道的发射前定标存在较大误差。利用敦煌戈壁滩辐射校正场可进行FY-2B可见光通道的在轨绝对定标。由于FY-2B对于敦煌场区的卫星天顶角接近50°，需要进行场地的方向特性BRDF修正。2002年7月对FY-2B进行了场地地表反射率、大气消光、探空等项同步测量，并对场地的方向特性进行了测量。资料处理结果表明，FY-2B可见光通道杂散光可影响定标精度达20%。长期监视表明FY-2B可见光通道探测器输出十分稳定。该文将4个可见光通道探测器场地定标得出的定标查找表列出，供用户参考使用。     

Seismic horizontal pullout capacity of shallow vertical anchors in sand

The concept of the equivalent free surface has been extended to determine the seismic horizontal pullout capacity of shallow vertical strip plate anchors buried in sand. The analysis has been done rigorously by using the method of stress characteristics. The results have been expressed in the form of non-dimensional charts. The pullout resistance has been found to reduce quite extensively with increase in the magnitude of horizontal earthquake acceleration. The results were compared with the previously published data, and it was seen that the computed pullout resistance with the proposed method was found to be lowest. This revised version was published online in July 2006 with corrections to the Cover Date.     

Impact of a Tropical Cyclone on Coastal Upwelling Processes

A three-dimensional numerical model is described to study theresponse of a coastal ocean excited by a tropical cyclone in the Bay of Bengal. The numericalexperiments have been carried out using the model to understand the dynamics and thermodynamics ofthe ocean due to different cyclonic systems approaching in different directions. In the firstexperiment, the model is used to simulate the vertical thermal structure of the ocean as a response ofpassage of the less intensified 1997 cyclone, which was skirting the east coast of India before crossingthe Bangladesh coast. The simulations are compared with the buoy data available during the storm period.In the next experiment, it is considered an idealized cyclone with hurricane winds movingnormal to the east coast of India crossing between Visakhapatnam and Kakinada to evolve thermalstructure and currents of the ocean. A net decrease of the SST of 6–7 °C is simulated whenthe severe cyclonic storm moved over the coastal ocean.