Development of a real-time algorithm for detection of solar wind discontinuities     

D. Vandev  K. Danov  P. Mateev  P. Petrov  M. Kartalev  N. Trendafilov  Z. K. Smith  M. Dryer 《Astrophysics and Space Science》1986,120(2):211-221

A study is presented of an algorithm, based on the statistical analysis of interplanetary magnetic field data, for the real-time detection of discontinuities in the solar wind. The analysis is based on the application of a sliding or searching algorithm together with a minimum variance treatment. A demonstration is given for a Pioneer data set from 29 August, 1966. This particular data set was chosen because it has been extensively studied (in terms of the fast forward MHD shock wave) by previous groups who utilized the three-dimensional Rankine-Hugoniot shock equations after identifying the shock on a subjective basis. Our procedure differs in that it is perfectly objective because of its searching technique. For this particular data set we identify the original shock with excellent agreement with the earlier studies of its normal vector, as well as an additional shock and tangential discontinuity, neither of which had been identified previously.  相似文献   

Geochemistry of re and trace elements in ferromanganese nodules and their genesis   总被引：1，自引：0，他引：1  

王贤觉  陈毓蔚  吴明清 《中国海洋湖沼学报》1986,4(3):211-226

Trace and RE element geochemistry and genesis have been studied with respect to ferromanganese nodules from the sediments of the Pacific, Atlantic and Indian oceans.  相似文献   

The Hα-cyclonic spectra of a flare loop system on 1981 April 27     

X. M. Gu  B. S. Li  Y. J. Ding  S. C. Li  Z. Li 《Solar physics》1983,87(1):155-164

The data such as the H-spectrum-spectroheliographic (SSHG) observations, the H-chromospheric observations, etc., of a flare loop prominence which occurred on the western solar limb on 1981 April 27 have been obtained at Yunnan Observatory. The distribution of the internal motions and the macroscopical motion of the flare loop prominence with time and space in the course of its eruption and ascension is derived from the comprehensive analysis of the data. The possible physical pictures and the instability of the motions of the loop are inferred and discussed.  相似文献   

Evolution of electron and proton temperatures in a flaring loop     

Nagai  F.  Wu  S. T.  Tandberg-Hanssen  E. 《Solar physics》1983,84(1-2):271-283

We have investigated numerically how a temperature difference between electrons and protons is produced in a flaring loop by adopting a one-fluid, two-temperature model instead of a single-temperature model. We have treated a case in which flare energy is released in the form of heating of electrons located in the top part of the loop.In this case, a large temperature difference (T _e/T _p 10) appears in the corona in the energy-input phase of the flare. When the material evaporated from the chromosphere fills the corona, the temperature difference in the loop begins to shrink rapidly from below. Eventually, in the loop apex, the proton temperature exceeds the electron temperature mainly due to cooling of the electrons by conduction down the loop and heating of the protons by compression of the ascending material. In the late phase of the flare (t 15 min from the flare onset), the temperature difference becomes less than 2% of the mean temperature of electrons and protons at every point in the loop.  相似文献   

A preliminary stable isotope study on Mogok Ruby, Myanmar     

Tzen-Fu Yui  Khin Zaw  Chao-Ming Wu 《Ore Geology Reviews》2008,34(1-2):192

The primary occurrence of ruby in the Mogok area, northern Myanmar is exclusively found in marble along with spinel–forsterite-bearing marble and phlogopite–graphite marble. These marble units are enclosed within banded biotite–garnet–sillimanite–oligoclase gneisses. Samples of these marbles collected for C–O stable isotope analysis show two trends of δ¹³C–δ¹⁸O variation resulting most likely from fluid–rock interactions. Ruby-bearing marble and phlogopite–graphite marble follow a trend with coupled C–O depletion, whereas spinel–forsterite-bearing marble follows a δ¹⁸O depletion trend with relatively constant δ¹³C values. Ruby formation might have resulted from CO₂-rich fluid–rock interaction, while spinel–forsterite-bearing marble was genetically related to CO₂-poor fluid–rock interaction. Both fluids may have arisen from external sources. Based on graphite Raman spectral thermometry, the estimated temperature for phlogopite–graphite marble, and probably ruby-bearing marble, was lower than 607 °C, and for spinel–forsterite-bearing marble, lower than 710 °C. Contrasting C/O diffusion between graphite/ruby/spinel/forsterite and calcite, local variations of isotopic compositions of newly formed minerals as a result of non-pervasive fluid infiltration, and open-system isotopic disturbance during cooling may have affected C-/O-isotopic fractionations between minerals. The estimated high formation temperatures for ruby and spinel/forsterite imply that the parental fluids may have been related to nearby igneous intrusions and/or metamorphic processes. Whether these two types of fluid were genetically related is unclear based on the present data.  相似文献   

印度共和国主要矿产资源及其地质特征   总被引：2，自引：0，他引：2  

张建华吴良士 《矿床地质》2008,27(4):541-542

印度共和国是南亚地区矿产资源比较丰富的国家,铁矿探明储量175.7亿吨;铝土矿探明储量26.54亿吨;锰矿探明储量1.35亿吨;铬铁矿储量5900万吨;重晶石储量3000万吨。目前,全印度已开发了89种矿产资源,其中有52种非金属矿产,11种金属矿产,22种稀有金属矿产,4种能源矿产。全国生产矿  相似文献   

Zircon U–Pb ages, Hf and O isotopes constrain the crustal architecture of the ultrahigh-pressure Dabie orogen in China     

Zi-Fu Zhao  Yong-Fei Zheng  Chun-Sheng Wei  Fu-Kun Chen  Xiaoming Liu  Fu-Yuan Wu 《Chemical Geology》2008,253(3-4):222-242

The crustal structure of the Dabie orogen was reconstructed by a combined study of U–Pb ages, Hf and O isotope compositions of zircons from granitic gneiss from North Dabie, the largest lithotectonic unit in the orogen. The results were deciphered from metamorphic history to protolith origin with respect to continental subduction and exhumation. Zircon U–Pb dating provides consistent ages of 751 ± 7 Ma for protolith crystallization, and two group ages of 213 ± 4 to 245 ± 17 Ma and 126 ± 4 to 131 ± 36 Ma for regional metamorphism. Majority of zircon Hf isotope analyses displays negative ε_Hf(t) values of − 5.1 to − 2.9 with crust Hf model ages of 1.84 to 1.99 Ga, indicating protolith origin from reworking of middle Paleoproterozoic crust. The remaining analyses exhibit positive ε_Hf(t) values of 5.3 to 14.5 with mantle Hf model ages of 0.74 to 1.11 Ga, suggesting prompt reworking of Late Mesoproterozoic to Early Neoproterozoic juvenile crust. Zircon O isotope analyses yield δ¹⁸O values of − 3.26 to 2.79‰, indicating differential involvement of meteoric water in protolith magma by remelting of hydrothermally altered low δ¹⁸O rocks. North Dabie shares the same age of Neoproterozoic low δ¹⁸O protolith with Central Dabie experiencing the Triassic UHP metamorphism, but it was significantly reworked at Early Cretaceous in association with contemporaneous magma emplacement. The Rodinia breakup at about 750 Ma would lead to not only the reworking of juvenile crust in an active rift zone for bimodal protolith of Central Dabie, but also reworking of ancient crust in an arc-continent collision zone for the North Dabie protolith. The spatial difference in the metamorphic age (Triassic vs. Cretaceous) between the northern and southern parts of North Dabie suggests intra-crustal detachment during the continental subduction. Furthermore, the Dabie orogen would have a three-layer structure prior to the Early Cretaceous magmatism: Central Dabie in the upper, North Dabie in the middle, and the source region of Cretaceous magmas in the lower.  相似文献   

Development of a 3D GIS and its application to karst areas   总被引：1，自引：0，他引：1  

Qiang Wu  Hua Xu  Wanfang Zhou 《Environmental Geology》2008,54(5):1037-1045

There is a growing interest in modeling and analyzing karst phenomena in three dimensions. This paper integrates geology, groundwater hydrology, geographic information system (GIS), database management system (DBMS), visualization and data mining to study karst features in Huaibei, China. The 3D geo-objects retrieved from the karst area are analyzed and mapped into different abstract levels. The spatial relationships among the objects are constructed by a dual-linker. The shapes of the 3D objects and the topological models with attributes are stored and maintained in the DBMS. Spatial analysis was then used to integrate the data in the DBMS and the 3D model to form a virtual reality (VR) to provide analytical functions such as distribution analysis, correlation query, and probability assessment. The research successfully implements 3D modeling and analyses in the karst area, and meanwhile provides an efficient tool for government policy-makers to set out restrictions on water resource development in the area.  相似文献   

Wind wave-forced fine sediment erosion during the slack water periods in Hangzhou Bay,China     

John Z. Shi  Wen-Jun Gu  Dian-Zhi Wang 《Environmental Geology》2008,55(3):629-638

The shallow water wave simulation model-SWAN incorporated with a simple fine sediment erosion model is applied to Hangzhou Bay, China, to model the horizontal distribution of the maximum bottom orbital velocity and corresponding fine sediment erosion rates induced by: (1) southeasterly steady winds (5, 20 and 30 m/s), (2) southwesterly steady winds (5 and 20 m/s); (3) northwesterly steady winds (5 and 20 m/s); (4) east-southeasterly steady winds (5 and 20 m/s); (5) easterly steady winds (5 and 20 m/s) under closed and unclosed boundaries; and (6) unsteady winds during the slack water periods. Results suggest: (1) the steady wind wave-induced maximum bottom orbital velocities and corresponding fine sediment erosion rates generally increased with the increasing steady winds; (2) closed and unclosed boundary conditions had more significant influences on modeled fine sediment erosion rates under 5 m/s easterly steady winds than 20 m/s; and (3) steady and unsteady wind wave-induced maximum bottom currents could be significant in eroding fine sediment bed in Hangzhou Bay. The results show implications for geomorphology, sedimentology, coastal erosion, and environmental pollution mitigation in Hangzhou Bay.  相似文献   

Environmental contamination of Zn,Cd, Ni,Cu, and Pb from industrial areas in Hamadan Province,western Iran     

M. Jalali  Z. V. Khanlari 《Environmental Geology》2008,55(7):1537-1543

Eleven surface soil samples from calcareous soils of industrial areas in Hamadan Province, western Iran were analyzed for total concentrations of Zn, Cd, Ni, Cu and Pb and were sequentially extracted into six fractions to determine the bioavailability of various heavy metal forms. Total Zn, Cd, Ni, Cu and Pb concentrations of the contaminated soils were 658 (57–5,803), 125.8 (1.18–1,361), 45.6 (30.7–64.4), 29.7 (11.7–83.5) and 2,419 (66–24,850) mg kg⁻¹, respectively. The soils were polluted with Zn, Pb, and Cu to some extent and heavily polluted with Cd. Nickel values were not above regulatory limits. Copper existed in soil mainly in residual (RES) and organic (OM) fractions (about 42 and 33%, respectively), whereas Zn occurred essentially as RES fraction (about 69%). The considerable presence of Cd (30.8%) and Pb (39%) in the CARB fraction suggests these elements have high potential biavailability and leachability in soils from contaminated soils. The mobile and bioavailable (EXCH and CARB) fractions of Zn, Cd, Ni, Cu, and Pb in contaminated soils averaged (7.3, 40.4, 16, 12.9 and 40.8%), respectively, which suggests that the mobility and bioavailability of the five metals probably decline in the following order: Cd = Pb > Ni > Cu > Zn.  相似文献