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991.
聊古-井逸出气氦数字化观测资料分析及其映震能力的初步研究 总被引:3,自引:0,他引:3
简要介绍了一种新型测氦仪-GWK-201型测氦仪,分析了聊古一井1998年9月1日~1999年11月30日的逸出气氦观测资料。结果表明:该资料的正常动态为近直线型,并且在附近4.0级地震前有显的异常显示,对今后的地震预报探索研究具有一定的参考价值。 相似文献
992.
活动态测量中滤材的选择及其应用 总被引:1,自引:1,他引:1
研究滤材对元素活动态测定结果及测定精密度的影响,综合考虑元素活动态测量结果的真实性以及土壤胶体的性质等因素,确定了2μm孔径的滤膜是用于活动态测量的较佳滤材,本研究对活动态测量方法的规范化、标准化具有重要意义。应用试验表明所选滤材适用于活动态测量。 相似文献
993.
地球深部流体演化与矿石成因 总被引:26,自引:2,他引:26
文中重点讨论含矿NaClH2 O溶液在从高温、高压向低温、低压条件改变时性质变化对矿石形成过程的影响。通过对含矿NaClH2 O溶液的实验观测获得对地球深部流体性质的新认识。地球深部的NaClH2 O流体大多处于超临界态流体 ,在上升过程中经减压降温后 ,通过临界态 ,进入低于临界态的热液状态。流体在这一跨越临界态的转变过程中造成了大多数矿石的沉淀。自然界里的许多矿石是在开放流动体系和在非平衡的化学动力学过程中形成的。开放流动体系矿物与水的反应动力学实验 ,证明一些矿石可能形成于流动热液。跨越临界态这一转变过程中的矿物水反应动力学实验结果表明了反应速率的大涨落。地球深部流体在上升过程中的性质演化、流动体系和非均相反应动力学是现代矿石成因研究的 3个关键问题 相似文献
994.
Plasticity model for sand under small and large cyclic strains: a multiaxial formulation 总被引:1,自引:0,他引:1
Achilleas G. Papadimitriou George D. Bouckovalas 《Soil Dynamics and Earthquake Engineering》2002,22(3):15
This paper presents the multiaxial formulation of a plasticity model for sand under cyclic shearing. The model adopts a kinematic hardening circular cone as the yield surface and three non-circular conical surfaces corresponding to the deviatoric stress ratios at phase transformation, peak strength and critical state. The shape of the non-circular surfaces is formulated in accordance with the experimentally established failure criteria, while their size is related to the value of the state parameter ψ. To simulate cyclic response under small and large shear strain amplitudes without a change in model parameters, it was found necessary to introduce: (a) a non-linear hysteretic (Ramberg–Osgood type) formulation for the strain rate of elastic states and (b) an empirical index of the effect of fabric evolution during shearing which scales the plastic modulus. This index is estimated in terms of a macroscopic second-order fabric tensor, which develops as a function of the plastic volumetric strain increment and the loading direction in the deviatoric plane. Comparison of simulations to pertinent data from 27 resonant column, cyclic triaxial and cyclic direct simple shear tests provide a measure for the overall accuracy of the model. 相似文献
995.
Lidunka Vo?adlo John BrodholtDavid P Dobson K.S Knight W.G MarshallG.David Price Ian G Wood 《Earth and Planetary Science Letters》2002,203(1):567-575
First-principles calculations have been used to determine the equation of state of Fe3C in both its low-pressure magnetically ordered and high-pressure non-magnetically ordered states; at 0 K the ferromagnetic transition was found to occur at about 60 GPa. In the high pressure, non-magnetically ordered regime at 0 K the material may be described by a Birch-Murnaghan third-order equation of state with V0=8.968(7) Å3 per atom, K0=316.62(2) GPa and K′=4.30(2). At atmospheric pressure the ferromagnetic phase transition in Fe3C occurs at ∼483 K; preliminary measurements of the thermal expansion by powder neutron diffraction show that this transition produces a large effect on thermoelastic properties. The volumetric thermal expansion coefficient in the paramagnetic phase was found to be 4.34×10−5 K−1 at T∼550 K. By applying a thermal expansion correction to the calculated equation of state at 0 K, predicted values for the density and adiabatic incompressibility of this material at core pressures and temperatures were obtained. These results appear to be sufficiently different from seismological data so as to preclude Fe3C as the major inner core-forming phase. 相似文献
996.
Sang-Heon Shim Thomas S. DuffyKenichi Takemura 《Earth and Planetary Science Letters》2002,203(2):729-739
The pressure-volume-temperature equation of state (EOS) of gold is fundamental to high-pressure science because of its widespread use as an internal pressure standard. In particular, the EOS of gold has been used in recent in situ multi-anvil press studies for determination of phase boundaries related to the 660-km seismic discontinuity. These studies show that the boundaries are lower by 2 GPa than expected from the depth of the 660-km discontinuity. Here we report a new P-V-T EOS of gold based on the inversion of quasi-hydrostatic compression and shock wave data using the Mie-Grüneisen relation and the Birch-Murnaghan-Debye equation. The previously poorly constrained pressure derivative of isothermal bulk modulus and the volume dependence of Grüneisen parameter (q=d lnγ/d ln V) are determined by including both phonon and electron effects implicitly: K′0T=5.0±0.2 and q=1.0±0.1. This combined with other accurately measured parameters enables us to calculate pressure at a given volume and temperature. At 660-km depth conditions, this new EOS yields 1.0±0.2 GPa higher pressure than Anderson et al.’s EOS which has been used in the multi-anvil experiments. However, after the correction, there still exists a 1.5-GPa discrepancy between the post-spinel boundary measured by multi-anvil studies and the 660-km discontinuity. Other potential error sources, such as thermocouple emf dependence on pressure or systematic errors in spectroradiometry, should be investigated. Theoretical and experimental studies to better understand electronic and anharmonic effects in gold at high P-T are also needed. 相似文献
997.
统一建模语言UML及应用实例 总被引:3,自引:0,他引:3
UML是从众多最好的软件工程实践经验中发展而来的一种建模语言。它用标准化的图形符号来表示面向对象系统的概念,使其在软件开发前期为用户和系统分析人员提供了可以相互交流的基础,也为软件开发中后期的开发人员提供了交流的依据。同时,UML作为一种模型语言,可与任何面向对象的开发过程相结合来进行使用。这些优点使它具有广泛的适用性。 相似文献
998.
Carrying capacity research has been carried out for a long time. However, synthesized carrying capacity researches based on
systematic views began only in the 1970s. There is even less work done in China. This paper tries to address both synthesized
carrying capacity research and its utilization in China. State spaces method from the systematic science was borrowed to construct
the conceptual model of regional carrying capacity. Based on the conceptual model and the surveys in the Bohai Rim area, we
construct a representative indicators system for quantifying regional carrying capacity in the Bohai Rim. While employing
system dynamic models we simulated the evolving trend of both the regional carrying states and regional carrying capacity
from 1999 to 2015. The results proved the statement that Bohai Rim is overall over-capacity for a long time and will be over-capacity
in the foreseeable future. Among all the restriction factors, water shortage and environmental pollution stand out to be the
two primary obstacles for Bohai Rim’s sustainable development. Regional differentiation analysis further indicates that coastal
areas of the Bohai Rim burden more than its overall level. However, Shandong province shows some good signs in addressing
the regional carrying capacity issues. The research is successful in addressing the quantification of regional carrying capacity
issues, but nonetheless it needs further refinery and more information. 相似文献
999.
Sujata Ramachandran 《Singapore journal of tropical geography》2002,23(3):311-332
The remarkable ease with which the xenophobic tenor of the Hindu Right nationalist organizations or Sangh Parivar found favour with many privileged Indians in the early 1990s cannot be easily or comfortably discounted. Indeed, it even perniciously swayed a moderate secular central government led by the long dominant Congress Party. By mid–1992, when Sangh Parivar made the manifold dangers of the unsanctioned immigration by growing numbers of poverty–stricken Bangladeshi Muslim peasants their rallying cry, the lenient attitude of the Indian state towards these immigrants had hardened with astonishing rapidity. Unsettled by this sweeping tide of Hindu chauvinism, a hurriedly enforced "Action Plan" to locate and identify these undocumented immigrants was followed by brisk efforts under "Operation Pushback" to deport them from New Delhi — India's capital city and locus of bureaucratic, political and financial power. Haphazard and sporadic in implementation, Operation Pushback, while unmasking partisan dispositions coursing through the Indian bureaucracy, also exemplified Congress' belated attempts at redeeming its enervated standing. It is also worth noting that the highly circumscribed material realities of the Bangladeshi immigrants residing in Delhi's numerous slums made them easy targets of these perverse politics, and that subsequent opposition, internally and from neighbouring Bangladesh, to the gratuitous brutality displayed towards the first groups of deportees contributed to the Operation's abrupt truncation. 相似文献
1000.
The geography of choice and diversity in the 'new' secondary education market of England 总被引:1,自引:0,他引:1
Chris Taylor 《Area》2002,33(4):368-381
The geography of education remains an under-researched area, particularly in light of major transformations in education provision over the last two decades. This paper reaffirms the position of a geographical approach to studying the education system by focussing upon the differential impact of two major features of national policy reforms on secondary school admissions in England: the desire to enhance choice and diversity in the provision of schooling. 相似文献