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991.
992.
Interstellar graphene could be present in the interstellar medium(ISM), resulting from the photochemical processing of polycyclic aromatic hydrocarbon(PAH) molecules and/or collisional fragmentation of graphitic particles. Indeed, by comparing the observed ultraviolet(UV) extinction and infrared(IR) emission of the diffuse ISM with that predicted for graphene, as much as ~ 2% of total interstellar carbon could be locked up in graphene without violating the observational constraints. While the possible detection of planar C24, a small piece of a graphene sheet, has been reported towards several Galactic and extragalactic planetary nebulae, graphene has not yet been detected in interstellar environments. In this work, we search for the characteristic IR features of C24 at ~ 6.6, 9.8 and 20 μm toward Sgr B2, a high-mass star formation region, and find a candidate target toward R.A.(J2000) = 267.05855?and Decl.(J2000) =-28.01479?in Sgr B2 whose Spitzer/IRS spectra exhibit three bands peaking at ~ 6.637, 9.853 and 20.050 μm which appear to be coincident with those of C24. Possible features of C60 are also seen in this region. The candidate region is a warm dust environment heated by massive stars or star clusters, associated with a WISE spot(a tracer of star formation activity), close to the HII region candidate IRAS 17450–2759, and is surrounded by seven young stellar object candidates within ~ 5′, suggesting that the creation and/or excitation of C24 could be related to star formation activities. 相似文献
993.
利用断裂力学观点前已得出震级 M、区域剪切应力值τ0, 震源破裂半径 a 之间的关系式[1]. 通过求a和M可算出应力值M, shear stress τ0 of the source region and radius a of the earthquake fracture (assumed eircular) was obtained previously, from which one can get the stress value τ0 if a and M are known. The direction of the stress field is determined by averaging the focal mechanism solutions of small earthquakes of the region. This paper discusses the variation of stress field τ0 with time for the source region before and after the Yan-Yuan Earthquake, Yunnan Province, occurred on November 7, 1976, magnitude 6.9 and compares the stress field with that of the neighbouring regions.The results are as follows:(1). Before the Yan-Yuan Earthquake, in the neighbouring region Zhong-Dian, the value of τ0 was four times higher than all other parts of the entire province of Yunnan.(2). In the Yan-Yuan region, from the beginning of 1976, the τ0 value increased substantially and meanwhile the average direction of stress field from small earthquake source mechanism solutions was essentially the same as that of the main shock. Thus, one can see the actual variation of the stress field before the Yan-Yuan Earthquake.A discussion regarding the errors and sources of errors in the computation of the τ0 valus has been made and also the possibility and the consequent error for comparing the τ0 values of different regions using a single recording station or many stations, analysed. 相似文献
994.
Shift-share Analysis on International Tourism Competitiveness - A Case of Jiangsu Province 总被引:5,自引:0,他引:5
SHI Chunyun ZHANG Jie YANG Yang ZHOU Zhang 《中国地理科学(英文版)》2007,17(2):173-178
Shift-share analysis has been confirmed a useful approach in the study of regional economics and many kinds of extended shift-share models have been advanced and put into practice in economic studies, but few have hitherto been introduced and applied to the tourism research in China. Moreover understanding the spatially competitive relationship is of paramount importance for marketers, developers, and planners involved in tourism strategy development. Based on international tourism receipts from 1995 to 2004, this study aims at probing into the spatial competitiveness of interna- tional tourism in Jiangsu Province in comparison with its neighbors by applying a spatially extended shift-share model and a modified dynamic shift-share model. The empirical results illustrate that exceptional years may exist in the ap- plication of dynamic shift-share models. To solve this issue, modifications to dynamic shift-share model are put forward. The analytical results are not only presented but also explained by the comparison of background conditions of tourism development between Jiangsu and its key competitors. The conclusions can be drawn that the growth of international tourism receipts in Jiangsu mainly attributes to the national component and the competitive component and Zhejiang is the most important rival to Jiangsu during the period of 1995-2004. In order to upgrade the tourism competitiveness, it is indispensable for Jiangsu to take proper positioning, promoting and marketing strategies and to cooperate and integrate with its main rivals. 相似文献
995.
We examine the behaviour of accretion flow around a rotating black hole in presence of cooling. We obtain global flow solutions
for various accretion parameters that govern the accreting flow. We show that standing isothermal shock wave may develop in
such an advective accretion flow in presence of cooling. This shocked solution has observational consequences as it successfully
provides the possible explanations of energy spectra as well as generation of outflows/jets of various galactic and extra-galactic
black hole candidates. We study the properties of isothermal shock wave and find that it strongly depends on the cooling efficiency.
We identify the region in the parameter space spanned by the specific energy and specific angular momentum of the flow for
standing isothermal shock as a function of cooling efficiencies and find that parameter space gradually shrinks with the increase
of cooling rates. Our results imply that accretion flow ceases to contain isothermal shocks when cooling is beyond its critical
value. 相似文献
996.
Raghavendra Vishnu Tadivaka Bhanu Priyanka Paruchuri Sridhar Miriyala Padma Raju Koppireddi Venkata Ratnam Devanaboyina 《Acta Geophysica》2017,65(4):777-784
The performance and measurement accuracy of global navigation satellite system (GNSS) receivers is greatly affected by ionospheric scintillations. Rapid amplitude and phase variations in the received GPS signal, known as ionospheric scintillation, affects the tracking of signals by GNSS receivers. Hence, there is a need to investigate the monitoring of various activities of the ionosphere and to develop a novel approach for mitigation of ionospheric scintillation effects. A method based on Local Mean Decomposition (LMD)–Detrended Fluctuation Analysis (DFA) has been proposed. The GNSS data recorded at Koneru Lakshmaiah (K L) University, Guntur, India were considered for analysis. The carrier to noise ratio (C/N0) of GNSS satellite vehicles were decomposed into several product functions (PF) using LMD to extract the intrinsic features in the signal. Scintillation noise was removed by the DFA algorithm by selecting a suitable threshold. It was observed that the performance of the proposed LMD–DFA was better than that of empirical mode decomposition (EMD)–DFA. 相似文献
997.
青藏块体北缘跨断层测量资料宏观分析 总被引:1,自引:1,他引:1
本文在系统整理青藏块体北缘跨断层测量资料的基础上,进行了形变类型的划分,探讨了不同类型形变所反映的断层运动性能。 相似文献
998.
In horizontally layered soils of different electrical properties, electrical potential distribution becomes complex and the
obtained resistivity data may be limited in reflecting the actual soil profile. Thus the objective of this study was to identify
the factors that affect resistivity measurement on the cone penetrometer and further investigate the sensitivity of measured
resistivity to different types and concentrations of contaminants at the subsurface level. First, a theoretical resistivity
equation was derived to provide a means of computing the geometric factor. The effective volume of measurement on the cone
penetrometer was investigated and laboratory soil box tests verified the dominance of partially high resistivity regions within
the effective volume of measurement over the apparent resistivity. Such effect was found to lead to possible discrepancies
between the recorded resistivity data and the actual depth of measurement. Measurements on contaminated soil layers indicated
that resistivity cones are efffective in delineating inorganic contaminants in soils of high water contents, and detecting
NAPLs floating above the groundwater table provided that soils adjacent to the plume are not dry of water.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
999.
???FG5????????????й?????????????????12?????????????????????????????????????????????????5??10 -8 ms -2??????????????峱????????????????????FG5??????????????Ms6.0??????????? 相似文献
1000.
为了解决现有静态重力测量在城市地下空洞探测时存在工作难度大、效率低等问题,本文提出了基于车载重力测量平台的城市地下空洞快速探测方法。采用国产高精度捷联式重力仪SAG搭建车载移动重力测量平台,在长春卫星广场附近进行动态重力测量试验。首先对测得数据进行楼房干扰校正;之后采用基于传统极值点深度估计(depth from extreme points,DEXP)方法改进的比值DEXP方法进行重力异常数据深度成像;最后采用Tilt梯度法对位场数据进行边界识别。选取轻轨站附近两条测线进行研究,得出测线在700~1 300m区域附近存在负值异常,在800和1 000m附近最佳深度分别是24和28m,构造指数分别为0.18和0.06;经分析符合实际地下轻轨站空洞类型和所在范围,验证了车载移动平台重力测量在城市地下空洞探测中展开的可能性和有效性。 相似文献