2010年玉树超剪切破裂地震破裂过程反演

为探讨玉树地震是否为超剪切破裂事件,利用Yagi的方法重新进行了此次地震震源破裂过程的反演。通过给定不同的破裂速度进行对比,发现当破裂速度为4.7km/s时,理论与实际观测结果拟合残差最小,且反演结果更符合实际。另据P波高频辐射能量包络反演,破裂传播速度在4.7～5.8km/s范围内,而该地区的剪切波速度则为3.0～3.6km/s,从而证明了此次地震超剪切破裂现象的存在。反演结果表明,此次地震在玉树段的NW和SE段形成了19和31km的地表破裂,而震中所在的中段由于隆宝湖拉分盆地的存在,造成了15km的未破裂区。超剪切破裂是造成SE段玉树县城遭受严重破坏的原因之一。     

Application of a new non-linear least squares velocity curve analysis technique for spectroscopic binary stars

Using measured radial velocity data of nine double lined spectroscopic binary systems NSV 223, AB And, V2082 Cyg, HS Her, V918 Her, BV Dra, BW Dra, V2357 Oph, and YZ Cas, we find corresponding orbital and spectroscopic elements via the method introduced by Karami and Mohebi (Chin. J. Astron. Astrophys. 7:558, 2007a) and Karami and Teimoorinia (Astrophys. Space Sci. 311:435, 2007). Our numerical results are in good agreement with those obtained by others using more traditional methods.     

Random walk forecast of urban water in Iran under uncertainty

Water Resources - There are two significant reasons for the uncertainties of water demand. On one hand, an evolving technological world is plagued with accelerated change in lifestyles and...     

Experimental investigation on the effect of wear flat inclination on the cutting response of a blunt tool in rock cutting

Acta Geotechnica - A vast majority of experimental researches focuses on the cutting action of a sharp cutter, while there has been limited experimental work devoted to the study of the contact...     

Calculation of fracture parameters and their effect on porosity and permeability using image logs and petrophysical data in carbonate Asmari reservoir,SW Iran

Evaluation of fractures and their parameters, such as aperture and density, is necessary in the optimization of oil production and field development. The purpose of this study is the calculation of fracture parameters in the Asmari reservoir using two electrical image logs (FMI, EMI), and the determination of fracture parameters’ effect on the porosity and permeability using thin sections and velocity deviation log (VDL). The results indicate that production in the Asmari reservoir is a combination of fractures and rock matrix. Fracture aperture (VAH) and fracture porosity (VPA) are only measurable with core and image logs directly. However, regarding core limitations, the image log has been recognized as the best method for fracture parameter determination due to their high resolution (2.5 mm). In this study, VDL log and thin sections have been used as auxiliary methods which may be available in all wells. The VDL log provides a tool to obtain downhole information about the predominant pore type in carbonates. Results indicate that between fracture parameters, VAH is considered as the most important parameter for determining permeability. For well No. 3, VAH ranges from minimum 51 × 10^?5 mm to maximum 0. 047 mm and VPA changes from min 10^?5% to maximum 0.02056%. For well No. 6, VAH varies from 5 × 10^?4 to 0.0695 mm and VPA varies from 10^?5 to 0.015%. Therefore, due to high fracture density and fracture aperture, it seems that most of effective porosity originates from fractures especially in well No. 3. However, VDL for well No. 6 indicates that intercrystalline and vuggy porosity are the dominant porosity. This result may be an indication for fracture set diversity in the two studied wells. While in well No. 3, they related to the folding and active faults, in well No. 6 they are only of folding type. Furthermore, results indicate the high capability for both of EMI and FMI image logs for calculation of fracture and vug parameters in the carbonate reservoirs.     

Inverse problem theory to chemo-poroelastic parameters estimation: an analytical/experimental investigation

Shale formation swelling is one of the main factors affecting wellbore instability and associated problems in drilling operation. In order to eliminate these problems, it is important to investigate formation characteristics and understand mechanisms of rock-fluid interaction, from chemical/mechanical point of view. Shale membrane efficiency is known as an important parameter affecting wellbore instability. In order to measure this parameter, many mathematical models and experimental efforts have been carried out which consider mechanical-chemical processes for rock-fluid interactions. In this study, the field equations governing the problem have been derived based on the linear chemo-poroelastic theory and solved using analytical/numerical methods. Afterward, a comprehensive workflow to characterize the chemo-poroelastic parameters of illite-rich shale is conducted in the laboratory. In fact, mineralogical and apparent properties of shale sample have been described and some setups were performed such as triaxial test and membrane efficiency. Then genetic algorithm has been applied to solve an inverse problem and get a match between experimental data and modeling results. Ultimately, the three important properties in shale-fluid interactions, i.e., shale membrane efficiency, hydraulic, and chemical diffusivity coefficient have been estimated. Comparing the simulation results with the experimental data indicates that the simulation model can appropriately simulate the pore pressure transmission test. With this approach, the required parameters can be estimated with good accuracy without using time-consuming and costly tests.     

The generalized second law for the interacting generalized Chaplygin gas model in non-flat universe enclosed by the apparent horizon

We investigate the validity of the generalized second law of gravitational thermodynamics in a non-flat FRW universe containing the interacting generalized Chaplygin gas with the baryonic matter. The boundary of the universe is assumed to be enclosed by the dynamical apparent horizon. We show that for the interacting generalized Chaplygin gas as a unified candidate for dark matter and dark energy, the equation of state parameter can cross the phantom divide. We also present that for the selected model under thermal equilibrium with the Hawking radiation, the generalized second law is always satisfied throughout the history of the universe for any spatial curvature, independently of the equation of state of the interacting generalized Chaplygin gas model.     

海草凋落叶的溶解有机物的释放及其生物地球化学意义

Dissolved organic matter(DOM) represents a significant source of nutrients that supports the microbial-based food web in seagrass ecosystems. However, there is little information on how the various fractions of DOM from seagrass leaves contributed to the coastal biogeochemical cycles. To address this gap, we carried out a 30-day laboratory chamber experiment on tropical seagrasses Thalassia hemprichii and Enhalus acoroides. After 30 days of incubation, on average 22% carbon(C), 70% nitrogen(N) and 38% phosphorus(P) of these two species of seagrass leaf litter was released. The average leached dissolved organic carbon(DOC), dissolved organic nitrogen(DON) and dissolved organic phosphorus(DOP) of these two species of seagrass leaf litter accounted for 55%, 95% and 65% of the total C, N and P lost, respectively. In the absence of microbes, about 75% of the total amount of DOC, monosaccharides(MCHO), DON and DOP were quickly released via leaching from both seagrass species in the first 9 days. Subsequently, little DOM was released during the remainder of the experiment. The leaching rates of DOC, DON and DOP were approximately 110, 40 and 0.70 μmol/(g·d). Leaching rates of DOM were attributed to the nonstructural carbohydrates and other labile organic matter within the seagrass leaf. Thalassia hemprichii leached more DOC, DOP and MCHO than E. acoroides. In contrast, E. acoroides leached higher concentrations of DON than T. hemprichii, with the overall leachate also having a higher DON: DOP ratio. These results indicate that there is an overall higher amount of DOM leachate from T. hemprichii than that of E. acoroides that is available to the seagrass ecosystem. According to the logarithmic model for DOM release and the in situ leaf litter production(the Xincun Bay, South China Sea), the seagrass leaf litter of these two seagrass species could release approximately 4×10~3 mol/d DOC, 1.4×10~3 mol/d DON and 25 mol/d DOP into the seawater. In addition to providing readily available nutrients for the microbial food web, the remaining particulate organic matter(POM)from the litter would also enter microbial remineralization processes. What is not remineralized from either DOM or POM fractions has potential to contribute to the permanent carbon stocks.