气泡声学特性探潜方法研究

文中提出了一种探测潜艇的新方法,通过分析由潜艇螺旋桨产生的气泡特有的声学特征来探测潜艇。潜艇螺旋桨产生的气泡在水中会滞留比较长的时间,分布也很广泛,这给利用尾流气泡探测潜艇提供了可行性。利用此方法探测安静型潜艇具有理论和技术上的可行性。     

大气背景场对云中液态水反演结果影响

基于机载对空微波辐射计GVR讨论应用BP神经网络算法反演液态水路径时大气背景资料对反演结果的影响,为合理选择训练样本获取更准确的液态水观测数据提供依据,同时有利于了解反演算法的探测适用范围。文章选择多个历史探空资料,按照历史资料时间序列长度、季节和区域进行分类,建立不同类样本集训练BP神经网络获取反演方程,选择样本检验集模拟计算每类反演方程的反演精度,通过反演精度对比分析大气背景资料差异在反演云中液态水时造成的影响。结果表明训练样本的大气背景时空差异影响反演结果,在一定时间范围内增加历史资料序列长度可以减小大气背景差异对反演误差的影响,但当时间序列长度到达一定程度时,增加历史样本量将不再是提高反演精度的一种有效措施。季节分类可以减小大气背景差异对反演误差的影响,但在实际应用中,资料分类带来样本容量减小,对一定时间序列长度的历史资料,按照季节进行分类并不能有效提高垂直累积液态水的反演精度。     

长白山天池火山气象站期晚期碱流质熔岩的岩石学研究

通过野外火山堆积物的相分析、岩石显微鉴定和造岩矿物化学分析,可以确认气象站期晚期碱流质熔岩是典型的溢流熔浆冷却固结形成的,不是碎成熔岩。熔岩流的顶部和底部是黑曜质碱流岩的表壳相,中部是致密厚层与薄层相间产出的、具有塑性变形的碱流岩的内部相。组成熔岩流的岩石具有斑状和聚斑结构,从表壳相向内部相基质依次发育玻璃质结构、（微）球粒结构和霏细结构。斑晶矿物钠透长石、钙铁辉石、铁橄榄石和少量石英出现在熔岩流的所有岩相中,而钠铁闪石、铁钠透闪石和钛铁矿则作为内部相基质中的显微斑晶出现。气象站期晚期碱流质熔岩是过铝质、过碱性的钠闪碱流质熔岩,属于碱性系列,与意大利潘泰莱里亚岛碱流岩相比,富Si、Al、K、Mg、Ca和P而贫Fe、Na、Mn和Ti。     

基于MAPGIS轴向分带序列软件的二次开发

建立矿床地球化学异常模式,确定盲矿预测标志的一个重要研究内容,是计算矿床的原生晕轴向分带序列.目前,计算分带序列主要是通过手工,或借助其它数据处理软件半自动实现的.针对这一点,这里在VC 6.0的开发环境下,结合MAPGIS强大的二次开发功能,就实现了格里戈良分带序列的计算,并且阐述了二次开发的一般方法和步骤.通过应用表明,该程序算法合理,操作简单,速度快,大大提高了工作效率.     

低渗透软弱岩非达西渗流拟启动压力梯度试验研究

利用新开发的高压渗流仪,对大尺寸低渗透性软弱岩进行了系统的试验测试。试验渗透压差波动幅度仅为0.01MPa,渗出端溶液体积变化量测试精度可达0.05ml。通过溶液体积变化与时间的线性关系,稳定渗流量大小可以精确测定。以稳定压差、流量法(即稳压法),试验验证了低渗透岩石的非达西渗流现象。并根据非达西流线性段的渗流特点,采用三种方法推算了拟启动压力梯度值,并通过实例说明"二次平均法"是拟启动压力梯度推算的最有效方法。     

柴北缘早古生代埃达克质花岗岩锆石定年及其地质意义

铁石观岩体位于柴达木盆地北缘中偏西段,是该地区新发现的具埃达克岩特点的花岗岩。岩石化学分析结果表明,铁石观岩体SiO2含量变化于71.36%~73.70%,Al2O3含量介于14.48%~15.64%之间,MgO含量为0.44%~0.71%,w(Sr)一般350×10-6,w(Yb)变化于0.67×10-6~1.58×10-6,w(Y)介于6.74×10-6~18.02×10-6,w(Sr)/w(Y)=21.32~72.49,富集LREE和大离子亲石元素,亏损HREE及高场强元素,与典型的埃达克岩相似。铁石观岩体锆石206Pb/238U年龄加权平均值为(422.0±6.4)Ma,代表了岩浆形成年龄。研究表明,铁石观岩体形成于大陆后碰撞造山阶段,为加厚陆壳重熔形成。     

用变分玻恩迭代方法重建二维非均匀介质结构

提出了用于二维轴对称非均匀介质结构的反演和成像的一种新的反演迭代方法──变分玻恩迭代方法（ＶＢＩＭ）．首先利用玻恩近似将非线性积分方程线性化,然后应用变分方法导出用于反演的电场积分方程．正演数据则利用高效的数值模式匹配方法获得．数值结果表明,ＶＢＩＭ与ＢＩＭ相比,其收敛速度、成像质量等均得到较大的改善。     

数字地震分析软件WSGNPLOT的改进与应用

利用MATLAB语言结合DK-1仪器的工作特性设计滤波器,并且利用DIMAS中WSGNPLOT地震分析软件运用到实际工作中,解决WGSNPLOT软件中长周期滤波器近震分析结果不理想的问题。提高近震的分析质量,并且对这个滤波器的工作特性进行对比分析。     

广州市部分城区地震小区划和震害预测

在特大城市开展地震小区划和震害预测在我国是一次新的尝试。广州密集的建筑物群、到处耸立的高楼大厦、横贯市区的高架路桥和立交桥,是其它中小城市不具有的。海量的数据资源、复杂的空间结构给地震灾害分析、空间数据处理带来了诸多挑战,在数据资料调查收集、分析处理技术、信息系统开发平台等方面要求更高,加深了研究难度。介绍了广州市部分城区地震小区划和震害预测的工作区概况、研究方法和内容及成果特点。     

Geology and Origin of the Dongping Alkalic-Type Gold Deposit, Northern Hebei Province, People's Republic of China

Abstract: The Dongping deposit, located near the center of the northern margin of the north China craton, is one of the largest gold deposits in China. It is spatially, temporally, and genetically associated with the shallowly-emplaced Hercynian Shuiquan-gou alkaline intrusive complex. The complex intrudes high-grade metamorphic rocks of the Archean Sanggan Group along a deep-seated fault zone within the north China craton. Four major ore bodies (Nos. 1, 2, 22, and 70), consisting mainly of a set of en echelon lenses and veins, have been delineated at the Dongping deposit. Hypogene hydrothermal activities can be divided into four periods from early to late including: (1) gold-bearing K–feldspar–quartz stockworks and veins; (2) disseminated sulfide and gold zones; (3) gold-bearing quartz veins, and (4) barren calcite-quartz veins. Individual veins and stockwork systems can be traced along strike for 125 to 600 m and downdip for 100 to 600 m; they range from 0. 5 to 3 m in thickness. The mineralogical composition of the ore in the first three hypogene periods is relatively simple. It is composed of pyrite, galena, sphalerite, magnetite, specularite, chalcopyrite, native gold, electrum, calaverite, and altaite. Gangue minerals include K–feldspar, quartz, sericite, chlorite, epidote, albite, and calcite. Ore grade averages 6 g/t Au, but varies between 4. 14 and 22. 66 g/t Au. Gold is generally fine-grained and not visible in hand specimen. Fluid inclusions in ore-bearing quartz of periods 1, 2, and 3 are CO₂–rich, variable salinity (2. 5–21 wt% equiv. NaCl), and have variable homogenization temperatures of 195° to 340°C. Quartz in the gold-bearing K–feldspar–quartz stockworks (period 1), disseminated sulfide and gold zones (period 2), and the gold-bearing quartz veins (period 3) has calculated δ¹⁸O_H2O values between –1. 7 and 6. 9%, and δ values of fluid inclusion waters between –101 and –66%. All these isotope data of the ore-forming fluids plot between the magmatic fluid field and the meteoric water line. Sulfide minerals disseminated in host rocks show positive δ³⁴S values of 1. 9 to 3. 5%. Pyrite separates from he gold-bearing K–feldspar–quartz stockworks and veins (period 1) have a δ³⁴S range of –4. 3 to 0. 5%, whereas δ³⁴S values of pyrite, chalcopyrite, galena, and sphalerite from the disseminated sul-fide and gold zones (period 2) and the gold-bearing quartz veins (period 3) vary from –5. 3 to –13. 4%. Gold ores are also characterized by relatively radiogenic lead isotope compositions compared to those of the alkaline syenite host rock. The data are interpreted as indicative of a mixing of lead from the alkaline intrusive complex with lead from Archean metamorphic rocks. The combined fluid inclusion measurements, sulfur, oxygen, hydrogen, and lead isotope data, and petrological observations indicate that the Dongping deposit was formed from the mixing of these magmatic fluids with meteoric waters. The deposit is, therefore, believed to be a product of Hercynian alkaline igneous processes within the north China craton.