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941.
The geothermal reservoir in Tianjin can be divided into two parts: the upper one is theporous medium reservoir in the Tertiary system; the lower one includes the basement reservoir inLower Paleozoic and Middle-Upper Proterozoic. Hot springs are exposed in the northern mountainand confined geothermal water is imbedded in the southern plain. The geothermal reservoir is in-cised by several fractures. In recent years, TDS of the geothermal water have gone up along withthe production rate increasing, along the eastern fracture zone (Cangdong Fracture and West Bai-tangkou Fracture). This means that the northern fracture system is the main seepage channel ofthe deep circulation geothermal water, and the reservoir has good connection in a certain area anddefinite direction. The isotopic research about hydrogen and carbon chronology indicates that themain recharge period of geothermal water is the Holocene Epoch, the pluvial and chilly period of20 kaBP. The karst conduits in weathered carbonate rocks of the Proterozoic and Lower Paleozoicand the northeast regional fracture system are the main feeding channels of Tianjin geothermalwater. Since the Holocene epoch, the geothermal water stayed at a sealed warm period. Thetracer test in WR45 doublet system shows that the tracer test is a very effective measure forunderstanding the reservoir's transport nature and predicting the cooling time and transportvelocity during the reinjection. 3-D numerical simulation shows that if the reinjection well keeps asuitable distance from the production well, reinjection will be a highly effective measure to extractmore thermal energy from the rock matrix. The cooling of the production well will not be a problem. 相似文献
942.
943.
Pogliani L 《Journal of computational chemistry》2003,24(9):1097-1109
The complete graph conjecture that encodes the inner-core electrons of atoms with principal quantum number n >or= 2 with complete graphs, and especially with odd complete graphs, is discussed. This conjecture is used to derive new values for the molecular connectivity and pseudoconnectivity basis indices of hydrogen-suppressed chemical pseudographs. For atoms with n = 2 the new values derived with this conjecture are coincident with the old ones. The modeling ability of the new homogeneous basis indices, and of the higher-order terms, is tested and compared with previous modeling studies, which are centered on basis indices that are either based on quantum concepts or partially based on this new conjecture for the inner-core electrons. Two similar algorithms have been proposed with this conjecture, and they parallel the two "quantum" algorithms put forward by molecular connectivity for atoms with n > 2. Nine properties of five classes of compounds have been tested: the molecular polarizabilities of a class of organic compounds, the dipole moment, molar refraction, boiling points, ionization energies, and parachor of a series of halomethanes, the lattice enthalpy of metal halides, the rates of hydrogen abstraction of chlorofluorocarbons, and the pED(50) of phenylalkylamines. The two tested algorithms based on the odd complete graph conjecture give rise to a highly interesting model of the nine properties, and three of them can even be modeled by the same set of basis indices. Interesting is the role of some basis indices all along the model. 相似文献
944.
W. Ren 《Colloid and polymer science》1992,270(10):990-998
Inverse relaxation is studied for hard elastic polypropylene (HEPP), rubber and non-elastic polypropylene. The results show that contractive stress, stress, and internal friction are three essential factors related to the phenomenon. A three-element model in which each element has a definite meaning is proposed to describe this phenomenon. The results also show that, in the first cyclic deformation, relaxation time increases with the increase of recovery for all the materials, which indicates that recovery viscosity increases with the increase of recovery, but the stress rising amplitude (SRA) of inverse relaxation has a maximum in the recovery range. Analysis indicates that SRA equals recovery internal friction (RIF) for ideal material in which stress is solely a function of strain, independent of paths, and approximately equals RIF for non-ideal material at a given strain. From this principle it is found that the order of the work counteracted by RIF for the four materials is the same as that of their second hysteresis loop, and the RIF of HEPP has a sudden increase at the later recovery range. 相似文献
945.
946.
947.
煤焦在燃烧过程中孔隙结构变化的模拟 总被引:4,自引:1,他引:4
煤焦在燃烧过程中的物理特性,如比表面积和孔径分布会发生连续变化,直接测量煤焦在燃烧过程中的孔隙结构变化很困难,但可以通过合适的数学模型来观察,二维的圆柱孔模型已大量用来对煤焦气化与燃烧过程中表面积和孔隙结构的变化进行模拟,这个模型把孔隙分成两大部分--大孔与小孔,因为小孔构成比表面的绝大部分,所以在反应过程中比表面积的变化可以由单一小孔模型来拟合,本文采用了用Tseng和Edgar提出的孔模型对几 相似文献
948.
949.
ADSORPTION OF 2,4-D ON MODIFIED HYPERCROSSLINKED POLYSTYRENE (NDA-99) AND XAD-4 RESIN 总被引:1,自引:0,他引:1
The adsorption behavior of pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) in aqueous solution has been investigated using a hypercrosslinked polystyrene adsorbent (NDA-99) modified by dimethylamine group as well as a nonionic macroporous adsorbent (XAD-4). The Langmuir and Freundlich isotherm models were employed to fit the experimental data to describe adsorption mechanism. It shows that NDA-99 resin exhibits an adsorption affinity for 2,4-D higher than XAD-4 resin owing to its exceptional micropore structure and the amine group of the hypercrosslinked matrix.Further studies indicate that the hydrogen bonding interaction and the stronger π-π conjugation play a significant role in the course of the adsorption of 2,4-D on NDA-99 resin, which is in agreement with the IR spectroscopic results and the △E values of HOMO (the highest occupied molecular orbit) of adsorbent and LUMO (the lowest unoccupied molecular orbit) of adsorbate calculated from the MINDO/3 model. 相似文献
950.
Chromate conversion coatings (CCCs) on AA7075‐T6 were characterized using scanning electron microscopy, focused ion beam sectioning and scanning transmission electron microscopy with nano‐electron dispersive spectroscopy line profiling. The thickness and composition of the CCC was different at different locations on the heterogeneous microstructure of AA7075‐T6. The coating formed on the matrix phase was much thicker than that formed on the coarse Al–Cu–Mg, Al–Fe–Cu and Mg–Si intermetallic particles. Nano‐electron dispersive spectroscopy line profiling indicated that the coating on the Al–Fe–Cu particles was similar to the CCC formed on the phase matrix, primarily a chromium oxide. However, the coatings on the Al–Cu–Mg and Mg–Si particles were mixed Al/Mg/Cr oxide and Mg oxide, respectively. The growth of CCC followed a linear‐logarithmic kinetic rate law. The observations of this study support the sol‐gel model of CCC formation. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献