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121.
We revisit the vertical structure of neutrino-dominated accretion flows (NDAFs) in spherical coordinates with a new boundary
condition based on the mechanical equilibrium. The solutions show that NDAF is significantly thick. The Bernoulli parameter
and neutrino trapping are determined by the mass accretion rate and the viscosity parameter. According to the distribution
of the Bernoulli parameter, the possible outflow may appear in the outer region of the disk. The neutrino trapping can essentially
affect the neutrino radiation luminosity. The vertical structure of NDAF is like a “sandwich”, and the multilayer accretion
may account for the flares in gamma-ray bursts. 相似文献
122.
123.
介绍了用GPS对台站数字化地震仪地理北方向的定位方法。试验表明,定向精度优于2′,完全满足地震仪器定向精度小于6′的要求。 相似文献
124.
125.
Impact of seasonal tide variation on saltwater intrusion in the Changjiang River estuary 总被引:1,自引:0,他引:1
An improved 3-D ECOM-si model was used to study the impact of seasonal tide variation on saltwater intrusion into the Changjiang River estuary, especially at the bifurcation of the North Branch (NB) and the South Branch (SB). The study assumes that the river discharge and wind are constant. The model successfully reproduced the saltwater intrusion. During spring tide, there is water and salt spillover (WSO and SSO) from the NB into the SB, and tidally averaged (net) water and salt fluxes are 985 m3/s and 24.8 ton/s, respectively. During neap tide, the WSO disappears and its net water flux is 122 m3/s. Meanwhile, the SSO continues, with net salt flux of 1.01 ton/s, much smaller than during spring tide. Because the tidal range during spring tide is smaller in June than in March, overall saltwater intrusion is weaker in June than in March during that tidal period. However, the WSO and SSO still exist in June. Net water and salt fluxes in that month are 622 m3/s and 15.35 ton/s, respectively, decreasing by 363 m3/s and 9.45 ton/s over those in March. Because tidal range during neap tide is greater in June than in March, saltwater intrusion in June is stronger than in March during that tidal period. The WSO and SSO appear in June, with net water and salt fluxes of 280 m3/s and 8.55 ton/s, respectively, increasing by 402 m3/s and 7.54 ton/s over those in March. Saltwater intrusion in the estuary is controlled by the river discharge, semi-diurnal flood-ebb tide, semi-monthly spring or neap tide, and seasonal tide variation. 相似文献
126.
A mutant (GQQ-M6) of a Sponge-Derived streptomyces sp. GQQ-10 obtained by UV-induced mutation was used for producing prodiginines (PGs). Single factor experiments and orthogonal array design (OAD) methods were employed for medium optimization. In the single factor method, the effects of soluble starch, glucose, soybean flour, yeast extract and sodium acetate on PGs production were investigated individually. In the subsequent OAD experiments, the concentrations of these 5 key nutritional components combined with salinity were further adjusted. The mutant strain GQQ-M6 gave a 2.2-fold higher PGs production than that of the parent strain; OAD experiments offered a PGs yield of 61mg L-1, which was 10 times higher than that of the initial GQQ-10 strain under the original cultivation mode. 相似文献
127.
P. Felenbok J. Guérin A. Fernandez V. Cayatte C. Balkowski R.C. Kraan-Korteweg 《Experimental Astronomy》1997,7(2):65-85
We are describing a new multi-fibre positioner, MEFOS, that was in generaluse at the La Silla Observatory, and implemented at the prime focus of theESO 3.6 m telescope. It is an arm positioner using 29 arms in a one degreefield. Each arm is equipped with an individual viewing system for accuratesetting and carries two spectroscopic fibres, one for the astronomical objectand the other one for the sky recording needed for sky subtraction. Thespectral fibres intercept 2.5 arcsec on the sky and run from the prime focusto the Cassegrain, where the B&C spectrograph is located. Afterdescribing the observational procedure, we present the first scientificresults. 相似文献
128.
Study of a comprehensive assessment method of the environmental quality of soil in industrial and mining gathering areas 总被引:1,自引:0,他引:1
Yang Guan Chaofeng Shao Qingbao Gu Meiting Ju Xueju Huang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(1):91-102
Industrial and mining activities have been recognized as major sources of heavy metal contamination in soil. Here, we developed a comprehensive assessment method for the soil environment in industrial and mining gathering areas based on the pressure–state–response model. Using this method, we assessed the environmental quality of soil in a typical industrial and mining gathering area in Tianjin City, China. The results are as follows: (1) The comprehensive environmental quality index of the soil in the study area was 0.532, which corresponds to an alert state and shows that the soil environment is generally poor. (2) The pressure, state, and response indexes were 0.609, 0.634, and 0.163, respectively, which suggests that the pressure in the soil environment of the study area is barely acceptable, and the state is merely passable. Furthermore, the response measures are not ideal. (3) The low response index scores indicate poor production processes, low pollutant treatment level, and unsatisfactory level of management by the enterprises in the study area. (4) The distribution of soil risks was found to be inseparably related to that of contamination sources and land use types. Furthermore, the distribution was uneven to a certain degree. Finally, we propose recommendations for the optimization, adjustment, and management of typical industrial and mining gathering areas with petrochemical, metallurgy, and other heavily polluting enterprises. 相似文献
129.
水震波是指地震波引起的井孔水位震荡现象.刘江等(1989)采用差容式加速度计作为拾震器,记录到了新丰江水库2.4级地震水震波中的PG和SG震相;舒优良等(2003)将BCC差压式水位仪与采样率为50Hz的地震数据采集器连接,周至深井成功记录到了2000年10月6日日本本州7.3级地震的数字化水震波波形,并与陕西数字地震台网部分台站的宽频带地震记录资料进行对比研究,得出有益的结论. 相似文献
130.
辜胜阻 《中国地理科学(英文版)》1993,3(2):97-111
Since cities and towns are places where those nonagricultural industries are centralized, urbanization is greatly interrelated with industrialization and de-agriculturalization. By means of this kind of interrelationship, Chinese urbanization level may be estimated with the formulas: P1=I1/I0/u0, Pr = N1/N0/u0. The urbanization after the founding of the People's Republic of China can be divided into the following 5 stages: the stage at the out set of industrialization (1949-1957); the high-speed urbanization stage (1958-1960); the first counter-urbanization stage (1961-1965); the second counter-urbanization stage (1966-1976); and the high-speed urbanization stage (1978-now). The characteristics of Chinese urbanization are: the industrialization launched by the government; the simultaneous development of urbanization of cities and urbanization of rural areas; the quite low capability of urbanization to absorb nonagricultural labor force; the incoordinate development of cities, etc. Before establishing a 相似文献