低频数字电磁测深仪器系统及其在攀-西地区的应用

本文介绍了在CTM-302型三分量磁通门磁力仪的基础上,研制的低频数字化大地电磁测深仪器系统;并根据该系统的功能和在攀-西地区的应用情况,对其发展前景进行了探索。     

G-880G海洋磁力梯度仪的改装与使用

将海洋磁力梯度仪用于海洋磁力总场测量是常见的实际需求,以G-880G海洋磁力梯度仪为例,分析了其结构及电流、电压情况,提出了一种将G-880G海洋磁力梯度仪改装用于地磁总场测量的方案,并论证了其可行性。     

“Methane on Mars: A product of H2O photolysis in the presence of CO”: Response to V.A. Krasnopolsky

The detection of CH₄ in the martian atmosphere, at a mixing ratio of about 10 ppb, prompted Krasnopolsky et al. [Krasnopolsky, V.A., Maillard, J.P., Owen, T.C., 2004. Icarus 172, 537-547] and Krasnopolsky [Krasnopolsky, V.A., 2006. Icarus 180, 359-367] to propose that the CH₄ is of biogenic origin. Bar-Nun and Dimitrov [Bar-Nun, A., Dimitrov, V., 2006. Icarus 181, 320-322] proposed that CH₄ can be formed in the martian atmosphere by photolysis of H₂O in the presence of CO. We based our arguments on a clear demonstration that CH₄ is formed in our experiments, and on thermodynamic equilibrium calculations, which show that CH₄ formation is favored even in the presence of oxygen at a mixing ratio 1.3×¹⁰⁻³, as observed on Mars. In the present comment, Krasnopolsky [Krasnopolsky, V.A., 2007. Icarus, in press (this issue)] presents his arguments against the suggestion of Bar-Nun and Dimitrov [Bar-Nun, A., Dimitrov, V., 2006. Icarus 181, 320-322], based on the effect of O₂ on CH₄ formation, the absence of kinetic pathways for CH₄ formation and on the inadequacy of thermodynamic equilibrium calculations to describe the martian atmosphere. In this rebuttal we demonstrate that experiments with molecular oxygen at a ratio of O₂/CO₂=(8.9-17)×¹⁰⁻³, exceeding the martian ratio, still form CH₄. Thermodynamic equilibrium calculations replicate the experimental CH₄ mixing ratio to within a factor of 1.9 and demonstrate that CH₄ production is favored in the martian atmosphere, which is obviously not in thermodynamic equilibrium. Consequently, we do not find the presence of methane to be a sign of biological activity on Mars.     

测高数据不准时的直升机航空瞬变电磁一维反演方法理论研究

航空电磁勘探中,高度计显示的发射线圈高度数据往往是不准确的,这可能会影响反演结果,出现假异常现象.针对这一情况,提出了一种高度计数据不准确条件下的航空瞬变电磁资料一维反演方法,在重构地电参数的同时也对发射线圈高度值进行校正.由于航空电磁反演问题是典型的病态问题,使用正则化反演方法,正则化因子由数据目标函数与模型目标函数之间的关系以自适应方式给出,使得反演迭代能稳定进行.以直升机航空瞬变电磁资料反演为例,用理论模型响应数据加入噪声进行反演,结果表明,无论初始高度值是高于真值还是低于真值,该反演方法均能够较好地重构地下介质参数和发射线圈高度值;作为反演初值的发射线圈高度测量值越准确时,反演迭代收敛速度就越快,反演效果也越好.     

Application of EDA technology and μClinux operating system in the earthquake precursor instruments

Using Altera's Quartus Ⅱ, Nios Ⅱ IDE and Sopc Builder development tools, the proton precession magnetometer principle host hardware platform is designed in a cyclone Ⅱ series FPGA chip (EP2C35). The proton precession magnetometer principle host core circuit's single-chip system-logic design is achieved by building and configuring the Nios Ⅱ soft-core processor, developing the IO interface and sensor control circuits, programming some hardware units' VHDL code, for example the equal precision cymometer and the DPLL. Through researching the embedded operating system configuration technology and building the NIOS Ⅱ soft-core processor's μClinux cross-compile environment, the μClinux system is transplanted to the NIOS Ⅱ environment. Another important task is writing the device drivers' and user programs' code. Through these work, the design realize the host function and achieve the expected target.

     

投影寻踪法的土地生态安全评价

针对土地生态安全评价所涉及的评价指标众多,数据量较大,评价体系具有明显的高维、非线性的特点.本文采用投影寻踪法构建土地生态安全评价模型,并应用模拟退火算法优化投影方向,将高维数据投影到低维空间上,根据优化出的一维投影值计算评价区域的土地生态安全度及主要影响要素.该模型在实际应用中取得了较为满意的效果,评价结果客观科学,...     

班公湖—怒江成矿带商旭造山型金矿床Ⅲ号矿段深部找矿潜力研究

西藏双湖县商旭造山型金矿床位于班公湖—怒江缝合带中段,矿体受NWW向的脆—韧性断裂构造控制,呈似层状、脉状产于中—下侏罗统木嘎岗日群混杂岩中。围岩为炭质板岩、变石英砂岩等。矿石类型主要为石英脉型和构造蚀变岩型,矿石构造以细脉状和角砾状为主,矿石矿物为自然金。矿床学与同位素地球化学研究认为木嘎岗日群含金建造为商旭金矿提供了主要物质来源,NWW向脆—韧性断裂构造为含金热液的运移和金的沉淀供了运输通道和就位空间,羌塘南缘早白垩世构造—岩浆活动为含金热液的运移提供了热动力,矿区内NWW向构造破碎带中变形强烈,具黄铁矿化、硅化蚀变的地段,为本矿区的找矿有利地区。土壤地球化学调查显示,Ⅲ号矿段南部,T-4、T-5异常区域具有较好的找矿潜力;电法测深资料显示,Ⅲ号矿段的控矿构造在深部还有延伸,并可能与区域较深大的断裂相连。综合分析认为,Ⅲ_(1-2)号矿体在标高4200m以下还具有较大的找矿潜力,通过进一步地质勘查工作,有望提高金资源量,扩大矿床规模。同时,初步总结了商旭造山型金矿床"找矿三步组合拳"的勘查工作方法。     

网上测绘相关文献的查找方法

掌握一个好的文献资料的查找方法对于我们的工作、学习、日常生活以及科学研究都有很大的帮助。本文阐述了利用Internet网查找测绘相关文献的方法,并介绍了一些测绘相关网站和网络数据库,还介绍了从Internet网上获取测绘文献的三种方式,以及在查找信息的过程中所使用的一般方法和选择检索词的技巧。     

磁通门仪器室建设要点

地磁观测条件的特殊性决定了仪器观测室建设具有难度，本文介绍了大连地震台按照《地震及前兆数字指导规范（试行）》要求建设磁通门仪器室的过程及结果。     

大连地震台GM3磁通门磁力仪的维护与应用

“九五”地磁数字化改造项目仪器配置分为两个部分，绝对观测仪－CTM－磁力仪和相对记录仪－GM3磁通门磁力仪，大连台自仪器装备以来，经过精心安装调试与观测摸索出一套仪器维护与高精度观测的经验，资料精度逐步达到规范要求，2001年11月9日通过验收，被专家组评价为“达到国内领先水平”。