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131.
the hypothesis that lineaments on Europa are fractures produced by tidal distortion and planetary volume change is examined by comparing the orientations of dark bands, triple bands, and cuspate ridges to fracture patterns predicted for tidal distortion due to orbital recession and orbital eccentricity. If short, reticulate dark band nnear the anti-Jove point are tension cracks which formed in response to tidal distortion, they could only have been produced by orbital eccentricity. Long, arcuate dark band and triple bands peripheral to the anti-Jove point orientations which suggest that they are strike-slip faults which formed in response to orbital recession. If cuspate ridges are compressional features, their orientations and distribution suggest that they formed in response to combined orbital recession and a decrease in planetary volume. Stresses due to orbital eccentricit could have produced tension cracks near the anti-Jove point only if tensile failure occurred either prior to the accumulation of orbital recession stresses or after they had relaxed. Surface fracturing, if a consequence of tidal deformation, places important constraints on the orbital evolution of Europa. 相似文献
132.
Wu Guang-jie 《Chinese Astronomy and Astrophysics》1990,14(4):454-460
Considering the errors transmitted from all pre-treatments, I suggest a “division” method for removing the sky background including interference fringes in CCD images. Compared to the traditional method, which may be called a “subtraction” method, the “division” method is easier to carry out and gives more accurate brightness measurement especially for the fainter images. 相似文献
133.
Based on the earthquake activity characteristics of the diamond block in the Sichuan-Yunnan region and by using the method of the meso-scope damage dynamics and damage evolution,we studied the damage evolution process for moderately strong earthquakes along two seismicbelts.The original combination patterns of all the units which illuminate the changes from stable state to destroyed state are given.All these patterns can direct the earthquake prediction practice in this region 相似文献
134.
135.
K. Golap N. Udaya Shankar S. Sachdev R. Dodson Ch. V. Sastry 《Journal of Astrophysics and Astronomy》1998,19(1-2):35-53
A new, meter-wave radio telescope has been built in the north-east of Mauritius, an island in the Indian Ocean, at a latitude
of -20.14‡. The Mauritius Radio Telescope (MRT) is a Fourier Synthesis T-shaped array, consisting of a 2048 m long East-West
arm and an 880 m long South arm. In the East-West arm 1024 fixed helices are arranged in 32 groups and in the South arm 16
trolleys, with four helices on each, which move on a rail are used. A 512-channel digital complex correlation receiver is
used to measure the visibility function. At least 60 days of observing are required for obtaining the visibilities up to 880
m spacing. The Fourier transform of the calibrated visibilities produces a map of the area of the sky under observation with
a synthesized beam width 4′ × 4.6′ sec(δ + 20.14‡) at 151.5 MHz.
The primary objective of the telescope is to produce a sky survey in the declination range –70‡ to –10‡ with a point source
sensitivity of about 200 mJy (3a level). This will be the southern sky equivalent of the Cambridge 6C survey. In this paper
we describe the telescope, discuss the array design and the calibration techniques used, and present a map made using the
telescope. 相似文献
136.
J. F. Rontani 《Marine environmental research》1985,16(4):301-314
Oxidation of alkyl-substituted benzenes by a marine mixed bacterial population showed no accumulation of phenyl acetic and phenyl acrylic acids, although more than 90 % of the substrates were converted to microbial cells and carbon dioxide. Photo-oxidation products were also used by bacteria to form assimilable intermediates. These reactions with mixed population constitute an interesting example of favourable interaction between bacterial degradation and photo-oxidation and can explain the disappearance of compounds listed as recalcitrant substrates. Key intermediates have been identified by gas chromatography and mass spectrometry. A mechanism based on their chemical structure is proposed for the degradation of alkyl-substituted benzenes containing side chains with odd and even numbers of carbon atoms. 相似文献
137.
The sorptive behaviour of natural estuarine colloids was investigated with benzene, naphthalene and anthracene. The equilibrium sorption isotherms were linear. Freundlich partition coefficients normalized to the organic content of the colloids for benzene, naphthalene, and anthracene were 920, 4060 and 510000, respectively. These values are at least an order of magnitude higher than those reported for corresponding soil/sediment systems. This suggests that hydrophobic compounds are more strongly bound to estuarine colloidal organic material.The effect of pH on sorption waas also studied. A significant decrease in sorption was observed when the ambient pH (8·01) of natural water was decreased by a factor of 2. The experimentally determined Koc values were regressed against the water solubilities of PAHs and compared with a corresponding predictine relationship developed for a soil/sediment system. Such information greatly facilitates prediction of PAH phase partitioning in natural waters. 相似文献
138.
文章概述了国外浮标在恶劣海况下发生的恶性事故,从而提出确保浮标安全可靠的重要性和在设计中必须解决的若干问题:合理的选型;正确的计算;可靠的结构和安全的锚锭系统。文章最后指出小型海洋调查浮标有广阔发展的前景。 相似文献
139.
为了探索塔克拉玛干沙漠夏季晴空对流边界层湍流结构和热对流运动规律,利用沙漠腹地探空及地表通量观测资料,开展了晴空对流边界层的大涡模拟研究。结果表明:(1)沙漠夏季晴空条件下,对流边界层湍能主要由地表热力浮力对流产生,机械剪切对边界层湍能的贡献较小,小尺度湍涡对湍能的耗散随高度呈减弱趋势,边界层湍能变化呈现间歇性特点。(2)沙漠夏季晴空边界层中存在着有组织的热对流泡现象,热泡最大上升速度可超过4.0 m·s-1;沙漠热对流运动一般呈羽状和网状分布特征,在上升运动区周围伴随有大片的下沉辐散区域。(3)地表感热和逆温层顶盖强度是控制和影响沙漠对流边界层发展的两个重要因素,感热增大,对流边界层变暖且高度升高;感热减小,对流边界层变冷且高度降低。在感热不变的条件下,逆温层顶盖强度越强,越不利于对流边界层发展,反之则相反。 相似文献
140.
随着太湖流域湖西区沿江引排工程的全面建成,以及区域水资源调度的开展,湖西区水文情势发生了一定变化。基于1986~2012年太湖流域湖西区出入湖水量、降雨量、沿江主要口门引排水量资料,采用Mann-kendall检验法、小波分析法和滑动检验法,对湖西区降雨量、沿江口门引排水量及净入湖水量的各月变化和周期变化特征进行研究,并对年净入湖水量增加的影响因素进行分析。结果表明:湖西区全年和汛期降雨量呈不显著的上升趋势,全年及汛期引水量、净引水量呈显著上升趋势,全年、汛期、各月净入湖水量均呈显著上升趋势。湖西区净入湖水量统计量在1997、1999、2001、2006年超出了临界线,其中,1997年净入湖水量由偏少转为偏多,可能与降雨由偏枯转为偏丰有关;1999年与湖西区沿江口门改扩建、口门调度以引水为主有关;2001、2006年则与环太湖巡测线路向湖边调整使控制水量增加有关。此外,湖西区净入湖水量的不断增加也与湖西区土地利用变化影响产汇流规律有关。 相似文献