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51.
板块碰撞造山模式难以解释造山作用在时间上的“滞后”和在空间上的“差位”现象,大量研究表明山脉隆升的动力来自深部,因此,探索深部地质过程的物理和化学机制及其导致的能量再分配是认识山脉隆升动力学机制的关键,若干线索表明地幔中的核反应中可能在岩石圈动力学演化过程中起过不可忽视的作用,通过分析U,Th等元素的地球化学性质及其在深变质过程中的行为,认为伴随板块俯冲发生的陆壳物质向地幔的再循环有可能在办流圈顶部形成富含U,Th,K等放射性亲石元素和碳质(石墨)的地质体,通过理论上的论证和对Oklo天然核反应堆遗迹的反演表明这些地质体可能有一部分具备了形成石墨核反应堆的条件。这种反应堆在亚临界状态下的断续运行有可能为其上方岩石圈中的岩浆作用提供热源,进入超临界状态时将可能导致深部核爆炸,成为地震,火山爆发和岩石圈破裂的动力来源,据此建立的山脉隆升的动力学初步模式,可以解释造山带的形成,高原的隆升,深源地震及其前兆的成因和金刚石及其相关岩石地壳浅部置位的机制。 相似文献
52.
A long-range transport model with nonlinear chemical reactions is described. The model contains 35 pollutants and 70 chemical reactions. This is a Eulerian model defined on a space domain containing the whole of Europe. The spherical space domain (corresponding to the Earth's surface covered by the model) is mapped into a square plane domain and discretized by using a 32×32 grid. The grid increments are equidistant (both along the Ox axis and along the Oy axis). The choice of values of the physical parameters involved in the model and the numerical treatment of the model are shortly discussed. The model is tested with meteorological data for 1985 and 1989. The numerical results are compared with measurements at stations located in different European countries. Extensive comparisons of ozone concentrations for July 1985 with measurements taken at 24 European stations are also carried out. Results concerning three episodes in July 1985 as well as results obtained in the study of the sensitivity of the ozone concentrations to variations of NO
x
and/or anthropogenic VOC emissions are presented. The advantages and the limitations of such a model are discussed. The model is continuously improved by adding new modules to it. The plans for improvements in the near future are outlined. 相似文献
53.
张永荣 《地震地磁观测与研究》1992,13(1):24-30
核爆炸与地震相比,围绕爆炸源的初动具有更多的向上记录和更高的振幅周期比,初动可以作为核爆与地震的一个识别标志。某些核爆炸的向下记录。或许是由于低信噪比的原因,记录到的是初至波的第二个半周;其余的也许是由于近P波走时曲线的反射波造成。 相似文献
54.
55.
Threat level green: Conceding ecology for security in eastern Europe and the former Soviet Union 总被引:1,自引:0,他引:1
Following the collapse of the Soviet Union, the predicted scenarios of Central Asian water wars and catastrophic nuclear accidents have failed to materialize. However, the Aral Sea continues to shrink apace, and dangerous Soviet-built nuclear reactors have since proliferated in the former eastern bloc. These seemingly paradoxical outcomes can in part be attributed to the framing of these environmental issues as security matters by leading international regulatory, aid and lending institutions. Integrating these environmental concerns with the realist worldview of security studies systematically emphasized security dimensions at the expense of ecological concerns even amongst organizations distant from traditional defense affairs. This article proposes that international security strategy in this period is one of environmental appeasement defined as the systematic granting of ecologically unfriendly concessions in order to reduce short-term security risks. The article presents evidence that this appeasement strategy generated seemingly impressive results in terms of ameliorating short-term security risks, while actually exacerbating the underlying ecological situation. The article argues that while the foundational environmental risks remain unaddressed, the associated security threats have likewise not been ultimately resolved. 相似文献
56.
57.
研究数字化核探测器输出脉冲信号的幅度提取问题。根据闪烁探测器的电路特性,推导了其脉冲信号理想曲线方程。综合利用三和值法、最小二乘法、试探法等方法,设计了该理想曲线拟合算法。由脉冲信号采样点数据,通过曲线拟合,计算出曲线的极大值,该值即为闪烁探测器输出脉冲信号的幅度。正反演数据结果对比表明,采用曲线拟合算法提取闪烁探测器输出脉冲信号幅度,其方案可行,计算结果更准确。相较于数字滤波和数字脉冲成形方法提取核探测器输出脉冲幅度,该算法更简单,对仪器的硬件处理速度要求更低。该方法开辟了核探测器脉冲幅度提取的新途径。 相似文献
58.
D. J. R. Wiggins G. J. Sharpe & S. A. E. G. Falle 《Monthly notices of the Royal Astronomical Society》1998,301(2):405-413
An off-centre detonation propagating near the interface between a C–O core and a He envelope in a Type Ia supernova explosion is modelled as a steady two-dimensional similarity solution at a plane interface. We assume that in both regions the energy release occurs in an infinitely thin detonation, which produces material in nuclear statistical equilibrium (NSE) in He and in nuclear statistical quasi-equilibrium in C–O. An α-network is then used to determine the effect of the associated rarefaction wave in the C–O on the final abundance of intermediate elements. We find that, although there is a significant effect, the rarefaction is not strong enough to quench the reactions and prevent the C–O from burning to NSE. 相似文献
59.
介绍与评述了I_a型超新星理论研究中最为突出的8个尚未解决的重要疑难问题,并简单介绍了国内围绕SNI_a开展的某些物理探讨研究. 相似文献
60.
Autoclaves are closed vessels in which liquids can be heated above their ‘normal' boiling points. As a consequence the pressure will rise. This equipment has permitted a variety of processes like the syntheses of organics and the leaching of metal ores. Pressure technologies can be used for accelerating reactions, for specific syntheses or they offer an environmental or economical alternative for existing processes. Wet pressure oxidation of sewage sludge, an organic waste product, has become a proven technology. If less oxygen is added than stoichiometrically required for a complete oxidation, cellulose will break down by a different reaction mechanism, releasing electrons. Under these circumstances reduction of inorganic compounds is possible. 相似文献