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101.
102.
WEI Heli LIU Qinghong XU Qingshan ZHAO Fengsheng SONG Zhengfang 《Acta Meteorologica Sinica》2001,15(2):249-256
Infrared solar spectra on clear days were measured automatically by an infrared solar spectrometer(ISS) with 0.4 cm-1 resolution developed by us.A line-by line(LBL) computation method was used to calculate theoretical atmospheric absorption.In the wavelength range of 3.410-3.438 μm.the absorption is mainly due to atmospheric methane and water vapor.Columnatmospheric methane was retrieved from the recorded infrared solar spectra.The seasonal variation of column atmospheric methane in Hefei has been obtained from the measuremental data of nearly 18 months since the April of 1997.and found that it is similar to that of background data.The instruments.principles of measurement and some of results were introduced,and the results are also discussed briefly in the paper. 相似文献
103.
In recent years, more and more studies are focused on the performance in seismic design instead of the strength of structures. People have realized that the structure deformation (displacement) can describe the damage more properly and directly than the strength (force). The displacement design spectra need to be constructed within more wide range of the period and the damping for the displacement-based seismic design. 相似文献
104.
J. A. Tossell 《Aquatic Geochemistry》2001,7(4):239-254
Changes in the UV spectra of As(OH)3 solutions with variations in pH and temperature have recently been used to determine the temperature dependence of the pKa of the acid. In previous studies I used quantum mechanical techniques to study changes in structure and vibrational spectra as a function of pH for arsenites and thioarsenites. I previously calculated UV spectra for ``molecular' minerals, like realgar As4S4. Here I use a number of different quantum mechanical methods, both Hartree-Fock and density functional theory based, to calculate the UV spectra for both a related simple well-characterized gas-phase molecule PF3 and for As(OH)3 and As(SH)3 and their conjugate anions and some neutral and anionic oligomers in aqueous solution. For the monomeric species small numbers of water molecules have been explicitly included, in a supermolecule or microsolvation approach. I find that UV absorption energies accurate to a few tenths of an eV can be obtained both for gas- phase PF3 and for neutral arsenious acid in aqueous solution, for which the UV absorption maximum is calculated to occur around 6.5 eV, consistent with experiment. Accurate calculation of the UV energies for arsenite anions in aqueous solution is much more difficult, since basis set size and solvation effects are considerably larger than for the neutral molecules, but fairly reliable results can still be obtained. Deprotonation is found to reduce the lowest calculated UV transition energy by about half an eV. Oligomerization also reduces the lowest calculated UV energy by at least half an eV. Replacement of one or all the –OH groups by –SH groups reduces the lowest calculated UV energies by about 2 eV. UV excitation energies have been calculated for oligomeric species as large as As3E3(EH)3 and As4E6, where E = O, S, and may be useful for identifying such species in solution. 相似文献
105.
北京地区一次特大强风过程边界层结构的研究 总被引:21,自引:2,他引:21
利用北京325 m气象塔资料对1993年4月9日北京地区出现的一次特大强风过程的边界层结构(风、温、风切变及阵风特征)进行了分析。随着该次大风的过境,边界层内风场出现数个风速高值中心,高度位于200~300 m,时间间隔1~3 h。伴随上层风速垂直切变和阵风特性。湍流能谱的计算结果表明了大尺度涡旋对边界层湍流微结构的影响。 相似文献
106.
107.
Anomalies found in the isotope ratios of ozone are traceable to the ozone formation process. Metastable electronic states may be responsible for the preferred production of the heavy molecules. While laboratory isotope data and first tropospheric results agree well in the magnitude of isotope enrichments, stratospheric measurements show often higher values. Only through the collection of ozone samples can sufficiently large amounts of gas be obtained to analyze the three isotopes 48O3, 49O3, and 50O3. Collector systems have been developed and successfully operated in the troposphere and in the stratosphere. They will play in the future an important role in atmospheric oxygen isotope studies. 相似文献
108.
109.
We have made a data collection and analysis system for recording microcracks in rock to study the three dimensional pattern
of fracture and the dynamic properties of rock during pressurization. This system, with 8 channel data detection, records
in real-time, from the initial microcracks to the final vibration waveform excited by the master fracture. The detected data
are recorded digitally at the hard disk of an IBM computer (or 286, 386 personal computer) as well as transmitted to disk.
The sampling rate for each channel is 10 MHz.
Collecting every acoustic emission events in the loaded rock sample with 8 channels by this system, mathematically modelling
the AE event travel time, and taking the coordinates of the AE event hypocenter and the three components of P wave velocity
as unknown parameters, we set up a set of residual equations for joint inversion, so that the three dimensional localization
of AE event hypocenters can be completed under variable velocities, which will lay foundations for the research on rock fracture
clearly.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismological Sinica,13, 489–495, 1991.
The design and development of the system, and the experiments are sponsored by the Chinese Joint Seismological Science Foundation. 相似文献
110.