The Q value variations in the preparing pro－cess of rock rupture

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A Study on the Light Curves of GRBs

It is generally believed that the complexity and variability of the light curves of gamma-ray bursts (GRBs) are caused by the internal shocks, which would occur when a rapid shell catches up a slower one and collides with it. The electrons in the shock layer are heated by the shocks and radiate via the mechanisms of synchrotron radiation and inverse Compton scattering. Based on relativistic kinematics, a relation between the photon number of the emission from the rapidly moving shock layer and the number of the photons received by an observer is derived. Then, employing the angular spreading of the internal shock emission, the curve equation and profile of a single pulse are obtained, and the shape is typically in the shape of a fast rise and exponential decline. Furthermore, by using the model of the successive collisions of multiple shells under the condition of reasonable parameters, the observed light curves are fitted with a rather good effect. Therefore, by this means, more different types of light curves of GRBs can be explained.     

Solar Type III Bursts and the Generation of Backward Langmuir Wave

It is generally believed that the conversion of Langmuir wave (LW) to electromagnetic wave is the generating mechanism of solar type III bursts. The Langmuir wave can be easily excited by the instability of the electron-beam current, and the interaction of the forward and backward Langmuir waves is considered to be the cause for the second harmonic of a type III burst, but, so far, the dispersion equation and generating mechanism of the backward Langmuir wave have not yet been thoroughly studied. For the equation of two-stream instability with temperature included, an analytical solution is derived. It is found that the dispersion relation of the forward LW strongly depends on the beam-current speed, while that of the backward LW depends only on the thermal velocity, when the other parameters are fixed. These analytical results are partially confirmed by particle-in-cell (PIC) simulations. With the PIC simulation, the generating mechanism of the backward LW is studied, and it is revealed that the backward LW can not be excited directly by the electron-beam current, and that its energy is obtained basically from the scattering of the forward LW. However, the electron-beam current does cause a direct amplification of the second harmonic of the forward LW.     

THE THEORY OF RESPONSE ANALYSIS OF FUZZY STOCHASTIC DYNAMICAL SYSTEMS WITH A SINGLE DEGREE OF FREEDOM

Most real-life structural/mechanical systems have complex geometrical and material properties and operate under complex fuzzy environmental conditions. These systems are certainly subjected to fuzzy random excitations induced by the environment. For an analytical treatment of such a system subjected to fuzzy random excitations, it becomes necessary to establish the general theory of dynamic response of a system to fuzzy random excitations. In this paper, the theory of response, fuzzy mean response and fuzzy covariance response of a single-degree-of-freedom (sdf) system to fuzzy random excitations in the time domain and frequency domain is put forward. The theory of response analysis of an sdf system to both stationary and non-stationary fuzzy random excitations in the time domain and frequency domain is established. Two examples are considered in order to demonstrate the rationality and validity of the theory, and the models of stationary filtered white noise and non-stationary filtered white noise fuzzy stochastic processes of the earthquake ground motion are set up. Methods of analysis for fuzzy random seismic response of sdf systems are put forward using the principles of response analysis of an sdf fuzzy random dynamic system.     

Drifting and Meandering of Olive Ridley Sea Turtles in the Bay of Bengal: Role of Oceanic Rossby Waves

Olive Ridley turtles in the Bay of Bengal are previously thought to migrate southward from their nesting ground, along the east coast of India (Orissa coast), towards Sri Lanka. Surprisingly, three of the four Platform Transmitter Terminal (PTT) attached turtles in April-June 2001 meandered off the east coast of India for about two months. It is found that these turtles meandered at the peripherals of cold core cyclonic eddy surrounded by warm core eddies on either side. Concentrations of prey for the turtles in those frontal regions are known to be abundant. Only one of the four PTT attached turtles migrated to the south along the frontal regions in the direction of geostrophic currents. It is found that the locations of these thermal fronts in the Bay of Bengal are primarily determined by the Oceanic Rossby waves and local Ekman pumping.     

基于高阶滑模控制器的水下潜器运动控制

水下环境复杂多变,由于水流的不可预知性和多变性,潜器的水动力系数往往无法准确获取,使得依赖这种参数的潜器运动控制算法的应用受到了很大的局限。为了解决控制器对模型参数的依赖,设计了一种基于高阶滑模控制算法的模型无关控制器,并通过设置合理的过渡过程,解决了这种控制算法依赖初值的弊端。仿真结果表明,位置和姿态的控制能够快速的收敛,误差很小并且不依赖于初始条件,控制器需调节参数很少,并且算法简单,适用于工程的实际需要。     

黑潮延伸体海域典型涡旋的次中尺度特征分析

本文基于卫星遥感资料和高分辨率ROMS(Regional Ocean Modeling System)数值模拟结果, 对黑潮延伸体海域典型中尺度涡旋的次中尺度特征进行了探讨。卫星观测和模拟结果显示, 黑潮延伸体涡旋海域伴随着活跃的次中尺度现象。涡旋演变与多尺度能量分析结果表明, 涡旋海域次中尺度动能的强弱与涡旋海域地转流动能有着密切联系, 锋生可能是涡旋边缘次中尺度动能增强的重要机制。次中尺度现象在中尺度涡旋海域具有沿地转流方向的复杂涡丝状结构特征, 意味着涡旋边缘较强的水平浮力梯度和地转流侧向剪切为次中尺度过程形成与发展提供了有利条件。此外, 垂向结构分析表明, 次中尺度过程能引起较大的垂向速度, 最大可达100m·day^-1, 该垂向速度可以影响至混合层下200m深度处, 对海洋内部的垂向物质能量交换、海—气相互作用等有着重要的影响。     

Geochemical Characteristics of Volcanic Rocks from ODP Site 794, Yamato Basin: Implications for Deep Mantle Processes of the Japan Sea

Deep mantle processes and the dynamic mechanism of magmatism in the Japan Sea Basin are important processes that have not been studied in detail. In this paper, systematic evaluation of basalt samples from the ocean drilling program Site 794 in the Japan Sea was performed, which included petrography, whole-rock major- and trace-element analysis, Sr-Nd-Pb isotopic composition, and electron microprobe analysis of plagioclase and clinopyroxene. These basalts belong to the tholeiitic series with porphyritic texture and massive Ca-rich plagioclase, clinopyroxene, and minor olivine phenocrysts. The basalts are characterized as flat rare earth elements and high-field-strength elements with remarkably low ratios of(La/Yb)N(0.75–2.51), significant positive anomalies of Ba, Sr, and Rb and no Eu anomaly(δEu = 0.99–1.36). The samples showed relatively high 87Sr/86Sr(0.70425–0.70522), 207Pb/204Pb(15.511–15.610), and 208Pb/204Pb(38.064–38.557) values and a low 143Nd/144 Nd ratio(0.51271–0.51295). The basalts from Site 794 can be divided into upper, middle, and lower volcanic rocks(UVR, MVR, and LVR) on the basis of their stratigraphic level. The MVR was geochemically derived from the depleted mantle, whereas the UVR and LVR originated from a nondepleted and relatively enriched mantle source with contributions from subducted Pacific plate fluid and sediments. Use of geothermobarometers indicates that the crystallization pressure for the UVR and LVR(6.25–11.19 kbar) was significantly higher than that of the MVR(3.48–5.84 kbar). The UVR and LVR may have been derived from the low-degree(5%–10%) partial melting of spinel lherzolite, while the MVR originated from a shallower mantle source with a high degree(10%–20%) of partial melting. In addition, the geochemical characteristics of the samples are consistent with a younger age(13–17 Ma) and the depleted composition of the MVR and an older age(17–23 Ma) and slightly enriched composition of the UVR and LVR. Therefore, temporal changes in the mantle source from old and enriched to young and depleted and subsequently to old and nondepleted may have been associated with progressive lithospheric extension and thinning, as well as at least two episodes of diverse asthenospheric upwelling and pull-apart tectonic motion in the Yamato Basin.     

要十分重视另一类型地质灾害的防治

文章提出另一类型地质灾害,即化学型地质灾害的定义及其分类。并认为化学型地质灾害不像物理型地质灾害那样发生瞬时灾害,而有一个延缓过程,但是一旦发生,难于挽救。化学型地质灾害体的主体是化学元素,开展地球化学调查,研究化学元素的赋存规律、土壤及沉积物承受各类元素的极限、各类元素活化的条件是揭示诱发化学型地质灾害机理的关键。因此要十分重视与加强化学型地质灾害的调查、研究、监测与治理工作。     

Holistic approach of GIS based Multi-Criteria Decision Analysis (MCDA) and WetSpass models to evaluate groundwater potential in Gelana watershed of Ethiopia

Appropriate quantification and identification of the groundwater distribution in a hydrological basin may provide necessary information for effective management, planning and development of groundwater resources. Groundwater potential assessment and delineation in a highly heterogeneous environment with limited Spatiotemporal data derived from Gelana watershed of Abaya Chamo lake basin is performed, using integrated multi-criteria decision analysis (MCDA), water and energy transfer between soil and plant and atmosphere under quasi-steady state (WetSpass) models. The outputs of the WetSpass model reveal a favorable structure of water balance in the basin studied, mainly using surface runoff. The simulated total flow and groundwater recharge are validated using river measurements and estimated baseflow at two gauging stations located in the study area, which yields a good agreement. The WetSpass model effectively integrates a water balance assessment in a geographical information system (GIS) environment. The WetSpass model is shown to be computationally reputable for such a remote complex setting as the African rift, with a correlation coefficient of 0.99 and 0.99 for total flow and baseflow at a significant level of p-value<0.05, respectively. The simulated annual water budget reveals that 77.22% of annual precipitation loses through evapotranspiration, of which 16.54% is lost via surface runoff while 6.24% is recharged to the groundwater. The calibrated groundwater recharge from the WetSpass model is then considered when determining the controlling factors of groundwater occurrence and formation, together with other multi-thematic layers such as lithology, geomorphology, lineament density and drainage density. The selected five thematic layers through MCDA are incorporated by employing the analytical hierarchy process (AHP) method to identify the relative dominance in groundwater potential zoning. The weighted factors in the AHP are procedurally aggregated, based on weighted linear combinations to provide the groundwater potential index. Based on the potential indexes, the area then is demarcated into low, moderate, and high groundwater potential zones (GWPZ). The identified GWPZs are finally examined using the existing groundwater inventory data (static water level and springs) in the region. About 70.7% of groundwater inventory points are coinciding with the delineated GWPZs. The weighting comparison shows that lithology, geomorphology, and groundwater recharge appear to be the dominant factors influence on the resources potential. The assessment of groundwater potential index values identify 45.88% as high, 39.38% moderate, and 14.73% as low groundwater potential zones. WetSpass model analysis is more preferable in the area like Gelana watershed when the topography is rugged, inaccessible and having limited gauging stations.