腾冲老厂坪子地区铜多金属矿

老厂坪子地区已发现十余个矿床(点),矿体赋存于花岗岩与碳酸盐岩接触带及其附近的断裂破碎带中,并受其双重控制。矿石品位较富,矽卡岩型和热液型成因,矿质来源于二叠系、三叠系碳酸盐岩及燕山早期岩浆岩。     

适用于遥感图像分类的对偶子空间分类器

本文在子空间分类器的基础上，对子空间的概念进行了扩展，提出了对偶子空间的概念和相应的分类算法。这种分类器不仅保持了子空间分类器分类准确度高的特点，而且分类速度有很大提高，因而更适用于大规模的遥感图像分类。     

渤海北部东岸海风锋活动及其触发对流特征分析

利用常规观测、雷达、卫星及加密自动气象站等资料,对2015年、2018年和2019年渤海北部东岸海风锋活动及其触发的对流特征进行统计分析.结果表明:不同年份渤海北部东岸海风锋活动的差异较大,海风锋主要出现在6—8月,其中7月最多;海风锋可分为沿山型、北部沿海型和混合型3种,其中沿山型占比70％以上,海风锋东移到达沿山地...     

双能光子吸收法提高CT衬度(密度)分辨率的研究

目的：提高CT衬度的分辨率，30年来，医学CT经历了原始的第一代CT发展至目前第5代高分辨率CT和高速电子束CT，其成像的空间分辨率和时间分辨率均有明显提高，但CT成像的衬度（密度）分辨率提高并不显著，而衬度分辨率与图像的灰度等级（灰阶）密切相关，是图像清晰度的重要参数。本文对应用双能量光子扫描吸收法以提高CT衬度（密度）分辨率的原理进行分析，并探讨其实际应用的可行性。     

双差分吸收激光雷达:-种能有效减小气溶胶对臭氧测量影响的方法

文中提出了一种新的激光雷达测量臭氧的方法：双差分吸收方法。理论分析和数值模拟表明这种方法可以有效减小气溶胶消光和后向散射对臭氧测量的影响，从而使激光雷达在气溶胶影响严重地区测量的臭氧精度比传统差分吸收激光雷达大大提高。利用（２８９，３１３；２７７．１，２９９．１ｎｍ）或（２６８．４，２８９；２７７．１，２９９．１ｎｍ）４波长进行双差分吸收可以用于对流层大气气溶胶含量丰富或分布不均匀地区臭氧的测量。利用（２９９．１，３４１．５；３０８，３５３ｎｍ）４波长进行双差分吸收可以对火山爆发后平流层臭氧进行较精确的测量。     

Comparison of three models of dispersion in dual porosity media

The work presented in this paper shows that the probabilistic approach as well as the fractional Brownian motion model are reliable to simulate the dispersion of contaminant in the dual porosity media. Three models were tested on experimental data obtained by tracer tests in chalk characterized by a primary and a secondary porosity: a numerical model (MT3DMS), a probabilistic model based on the Bayesian approach and a fractional Brownian model. By using Einstein’s rule, it is demonstrated that the dispersion coefficient is time dependent and that the dispersion is ballistic which is a particular case of superdiffusion. A test of sensitivity was carried out and shows that the numerical model is slightly suitable to simulate the concentration in time and space for a given discharge starting from the physical parameters obtained by calibration for an other discharge because of the great sensitivity of its parameters according to the hydrodynamic conditions. On the other hand, the variability of the parameters of the two other models does not generate important errors on the values of simulated concentrations when other hydrodynamic conditions are considered.     

基于周向磁场有限元方法的双侧向测井影响因素分析

电流线分布是评价双侧向测井仪器探测性能的一种辅助手段.通常采用基于电位的有限元数值模拟方法,通过对电位的微分获得电流线的分布,这种处理方法引入了额外误差.为解决此问题,本文提出了一种基于周向磁场强度的有限元方法,通过对视电阻率和电流线的数值模拟验证了新方法的正确性,且新方法在计算电流线方面优于电位法.在此基础上,针对泥浆低侵和高侵两种情况,模拟了深浅侧向测井的视电阻率响应和电流线的分布,分析了侵入带对双侧向测井响应的影响规律.

     

A performance comparison of single and dual frequency GPS ambiguity resolution strategies

The impact of observation selection, observation combination and model parameterization on GPS carrier phase ambiguity resolution and position accuracy under operational conditions is investigated. The impact of an ionospheric bias for a generic linear combination of L1 and L2 measurements is assessed and the results are used to clearly outline the desirable characteristics for improving ambiguity resolution versus positioning accuracy performance. Ambiguity resolution performance and position accuracy are shown for widelane (WL), L1-only, and ionospheric-free (IF) combinations. Several techniques for dealing with the ionospheric bias are also presented and compared, including stochastic ionospheric modelling. Multiple carrier phase combination solutions estimated in the same filter are also compared. The concept of an optimal processing strategy—in terms of both reliable ambiguity resolution and high accuracy positions—is presented. In total, eight strategies, which vary in observables and parameters, are tested on several datasets ranging from 13 km to 43 km.     

双参数展开CRP叠加和速度分析方法研究

椭圆展开共反射点(CRP)方法可以获得比常规倾角时差校正(DMO)方法更近似的零偏移距时间剖面和相应CRP速度场.大量研究和实践证实,在非均质性较弱的地区,该方法取得的成果显著.但由于该方法没有考虑速度的横向变化和转换波等情况,当地下介质存在较强非均质性时,该方法不再准确,需要引进反映速度横向变化的双参数(上行波与下行波的平均速度和速度比)进行改进.本文详细推导了引入双参数后的叠加和速度分析算法,并通过数值模型和地震资料处理证实,修正后的算法可以更好地解决地质复杂地区速度建模和叠加成像问题.