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991.
992.
993.
L. Ma G. Z. Xie T. F. Yi S. B. Zhou K. H. Li X. Zhang H. Dai 《Astrophysics and Space Science》2010,327(1):35-58
We present the results of the monitoring of a sample of 5 HBLs in the B, V and R bands during 2003–2008. All sources in our monitoring project show significant rapid optical variations, except 1ES 1959+650, however; for 1ES 1959+650, the gamma-ray variability on a timescale of ~7 hours has been observed by Holder et al. (Astrophys. J. 583:L9, 2003). Using these variability timescales, we estimate the black hole masses for each source with the Kerr black hole theory. 相似文献
994.
Based on Hinode SOT/NFI observations with greatly improved spatial and temporal resolution and polarization sensitivity, the lifestory of
the intranetwork (IN) magnetic elements are explored in a solar quiet region. A total of 2282 IN elements are followed from
their appearance to disappearance and their fluxes measured. By tracing individual IN elements their lifetimes are obtained,
which fall in the range from 1 to 20 min. The average lifetime is 2.9±2.0 min. The observed lifetime distribution is well
represented by an exponential function. Therefore, the e-fold characteristic lifetime is determined by a least-square fitting
to the observations, which is 2.1±0.3 min. The lifetime of IN elements is correlated closely with their flux. The evolution
of IN elements is described according to the forms of their birth and disappearance. Based on the lifetime and flux obtained
from the new observations, it is estimated that the IN elements have the capacity of heating the corona with a power of 2.1×1028 erg s−1 for the whole Sun. 相似文献
995.
Observed winds,turbulence, and dispersion in built-up downtown areas of Oklahoma City and Manhattan 总被引:2,自引:2,他引:0
Wind and tracer data from the Oklahoma City Joint Urban 2003 (JU2003) and the Manhattan Madison Square Garden 2005 (MSG05)
urban field experiments are being analyzed to aid in understanding air flow and dispersion near street-level in built-up downtown
areas. The mean winds are separately calculated for groups of anemometers having similar exposures such as “near street level”
and “on building top”. Several general results are found, such as the scalar wind speed at street level is about 1/3 of that
at building top. Turbulent standard deviations of wind speed components and temperature, and vertical fluxes of momentum and
sensible heat, are calculated from sonic anemometers near street level at 20 locations in JU2003 and five locations in MSG05,
and from two rooftop locations in MSG05. The turbulence observations are consistent with observations in the literature at
other cities, although the JU2003 and MSG05 data are unique in that many data are available near street level. For example,
it is found that the local (i.e., at the measuring height) averages about 1.5 and the local averages about 0.25 in the two cities, where is the standard deviation of vertical velocity fluctuations, is the friction velocity, and u is the wind speed. The ratio of temperature fluctuations to temperature scale, , averages about −3 in both cities, consistent with similarity theory for slightly unstable conditions, where is the standard deviation of temperature fluctuations, and is the temperature scale. The calculated Obukhov length, L, is also consistent with slightly unstable conditions near street level, even at night during JU2003. The SF6 tracer concentration observations from JU2003 are analyzed. Values of for the continuous releases are calculated for each release and arc distance, where is the 30-min average arc maximum concentration, Q is the continuous source emission rate, and u is the spatial-averaged wind speed in the downtown area. The basic characteristics of the JU2003 plot of averaged agree reasonably well with similar plots for other urban experiments in Salt Lake City and London (i.e., at . A is found to be about 3 during the day and about 10 during the night. 相似文献
996.
德州气候变化与建筑物防腐 总被引:2,自引:0,他引:2
利用德州11县市1951~2005年温度、降水资料,计算气候干燥度,1981~2005年与1951~1980年相比全市干燥度由1.45增大到1.64,已由原来的半湿润气候变化为半干旱气候。各县市降水量呈减少趋势,平均每10年减少19.64mm;气温呈上升趋势,平均每10年升高0.11℃,冬季升高0.30℃,冬季增温显著,北部县市已由原来的冰冻区变化为微冻区,全市均为微冻区。由于气候条件变化,相应场地环境类别与腐蚀介质指标的调整系数标准应作调整改变,场地环境类别由Ⅱ类转变为Ⅰ类,腐蚀介质指标的调整系数均取0.9。 相似文献
997.
998.
High-pressure granulite from Western Kunlun,northwestern China: Its metamorphic evolution,zircon SHRIMP U-Pb ages and tectonic implication 总被引:1,自引:0,他引:1
QU JunFeng ZHANG LiFei AI YongLiang L Zeng WANG JianPing ZHOU Hui & WANG ShiYan MOE Key Laboratory of Orogenic Belts Crustal Evolution School of Earth Space Science Peking University Beijing China Henan Polytechnic University Jiaozuo China Geological Survey of Henan Province Zhengzhou China 《中国科学D辑(英文版)》2007,50(7):961-971
High-pressure mafic granulites occurring as lenticular bodies within garnet-amphibolites in Kangxiwar Fault have been first reported in this paper. The P-T conditions of two metamorphic stages were ob-tained using calibrated geothermal barometers and ThermoCalc Program. The peak metamorphic con-dition of these high-pressure granulites is about 760―820℃,1.0―1.2 GPa and the retrograde meta-morphic condition is about 620―720℃,0.7―0.8 GPa. The petrological studies show that they have a near-isobaric cooling P-T... 相似文献
999.
Journal of Geographical Sciences - Due to the atmospheric nuclear weapon tests carried out, terrestrial environments have been extensively contaminated by global fallout of plutonium (Pu)... 相似文献
1000.
Geochemical characteristics,cooling history and mineralization significance of Zhangtiantang pluton in South Jiangxi Province,P.R. China 总被引:1,自引:0,他引:1
The zircon SHRIMP dating of the Zhangtiantang granite gave an age of 159±7 Ma., which shows that the granite was produced
at the early Late Jurassic. The Ar-Ar plateau ages of biotite and K-feldspar from the Zhangtiantang pluton are 153.2±1.1 Ma
and 135.8±1.2 Ma, respectively. The Ar-Ar anti-isochrone ages of biotite and K-feldspar are 152.5±1.7Ma and 135.4±2.7Ma, respectively.
The ages represent the isotopic closure ages of minerals in the pluton. The Zhangtiantang granites are regarded as peraluminous
crust-derived type granites to possess the typical geochemical characteristics of calc-alkaline rocks on continental margin,
with enriched Si, K, Al (average value of A/CNK as 1.18), HREE, Rb, U, and Th, heavily depleted V, Cr, Co, Ni, Ti, Nb-Ta,
Zr, Sr, P, and Ba, strongly negative Eu and common corundum normative (average value of C as 1.84). The εNd(t) values of the Zhangtiantang granite are −5.84 to −7.79, and t
2DM values are 1.69 to 1.83 Ga, which indicates partial melting of continental-crust metamorphic sedimentary rocks during the
Middle Proterozoic.
The cooling history of the Zhangtiantang granitic pluton indicates that the cooling velocity of pluton was faster (about 67°C/Ma)
from zircon (158 Ma) to biotite (152 Ma), and was slower (about12°C/Ma) from biotite (152.5 Ma) to K-feldspar (135.8 Ma).
It can be deduced that the temporal gap (about 10 Ma) between the granite formmation and W-Sn mineralization in South China
may be related to ordinary magma-hydrothermal processes by the variational cooling curve of the pluton. The Zhangtiantang
pluton was formed in a compressive setting, with differentiation evolution and mineralization occurring in a relative relaxation
setting. 相似文献