Polarization of loop-top and footpoint sources in microwave bursts     

Su  Y.N.  Huang  G.L. 《Solar physics》2004,219(1):159-168

The polarization is analyzed in four microwave bursts with one loop-top and two footpoint sources observed at 17 GHz with the Nobeyama Radioheliograph (NoRH). The loop-like structure of the four events is confirmed by simultaneous SOHO/MDI magnetograms and TRACE/EUV images or Yohkoh/SXT images. The heliocentric distance of the four events is greater than 30°. The three microwave sources in each given burst are polarized in the same sense. This may be interpreted in terms of extraordinary mode emission, taking into account the polarity of the underlying magnetic field and propagation effects, which may lead to inversion of the sense of polarization in the limbward foot and loop-top source of the flaring loop.  相似文献   

青海省大柴旦镇红柳沟金矿床地质特征及其成因     

吴正寿  邓元良  苏生顺 《青海国土经略》2001,(1)

通过对红柳沟金矿床地质特征及围岩蚀变的研究,总结了金矿控矿因素及其富集规律,认为该矿床的成因为动力变质热液型。  相似文献   

A One-Dimensional Relativistic Shock Model for the Light Curve of Gamma-ray Bursts     

Cheng-Yue Su  Yi-Ping Qin  Jun-Hui Fan  Zhang-Yu Han National Astronomical Observatories/Yunnan Observatory  Chinese Academy of Sciences  Kunming  Graduate School of Chinese Academy of Sciences  Beijing Department of Physics  Guangdong University of Technology  Guangzhou Center for Astrophysics  Guangzhou University  Guangzhou Department of Mechanics  University of Science  Technology of China  Hefei 《中国天文和天体物理学报》2006,6(3):323-330

We investigate the forming of gamma-ray burst pulses with a simple one-dimensional relativistic shock model. The mechanism is that a "central engine" drives forward the nearby plasma inside the fireball to generate a series of pressure waves. We give a relativistic geometric recurrence formula that connects the time when the pressure waves are produced and the time when the corresponding shocks occurred. This relation enables us to relate the pulse magnitude with the observation time. Our analysis shows that the evolution of the pressure waves leads to a fast rise and an exponential decay pulses. In determining the width of the pulses, the acceleration time is more important than that of the deceleration.  相似文献   

A Statistical Study of Rhessi Flares     

Yang Su  W. Q. Gan  Y. P. Li 《Solar physics》2006,238(1):61-72

A statistical analysis of RHESSI X-ray flares in the 12–25 keV band during the period from February 2002 to June 2005 is presented. We found that a power-law with an index of 1.80± 0.02 can fit well the frequency distribution of the peak count rates. This power-law does not change significantly with time. However, the frequency distribution of the flare durations cannot be fitted well by a single power-law. There is a weak correlation between the peak count rates and the characteristic times like rise times, decay times, or durations. But the correlation between the rise times and decay times seems to be strong. We discuss the results obtained and compare them with previous works. The frequency distribution of rise times for the sub-group events with a similar magnitude of peak count rates is also shown. In particular, we propose a new parameter R _a , the growth factor of the count rate, defined as the peak count rate divided by the rise time, to reflect the characteristics of the rising phases of flares. The distribution of R _a is shown and discussed.  相似文献   

Analysis of Magnetic Shear in An X17 Solar Flare on October 28, 2003     

Y. N. Su  L. Golub  A. A. Van Ballegooijen  M. Gros 《Solar physics》2006,236(2):325-349

An X17 class (GOES soft X-ray) two-ribbon solar flare on October 28, 2003 is analyzed in order to determine the relationship between the timing of the impulsive phase of the flare and the magnetic shear change in the flaring region. EUV observations made by the Transition Region and Coronal Explorer (TRACE) show a clear decrease in the shear of the flare footpoints during the flare. The shear change stopped in the middle of the impulsive phase. The observations are interpreted in terms of the splitting of the sheared envelope field of the greatly sheared core rope during the early phase of the flare. We have also investigated the temporal correlation between the EUV emission from the brightenings observed by TRACE and the hard X-ray (HXR) emission (E > 150 keV) observed by the anticoincidence system (ACS) of the spectrometer SPI on board the ESA INTEGRAL satellite. The correlation between these two emissions is very good, and the HXR sources (RHESSI) late in the flare are located within the two EUV ribbons. These observations are favorable to the explanation that the EUV brightenings mainly result from direct bombardment of the atmosphere by the energetic particles accelerated at the reconnection site, as does the HXR emission. However, if there is a high temperature (T > 20 MK) HXR source close to the loop top, a contribution of thermal conduction to the EUV brightenings cannot be ruled out.  相似文献   

Attenuation Compensation and Anisotropy Correction in Reverse Time Migration for Attenuating Tilted Transversely Isotropic Media     

Mu  Xinru  Huang  Jianping  Li  Zhenchun  Liu  Yanli  Su  Laiyuan  Liu  Junzhou 《Surveys in Geophysics》2022,43(3):737-773

Surveys in Geophysics - The propagation of seismic waves in attenuating and anisotropic earth media is accompanied by amplitude attenuation and phase distortion. If these adverse effects are not...  相似文献   

The Paleogene to Neogene climate evolution and driving factors on the Qinghai-Tibetan Plateau     

Zhao  Jiagang  Li  Shufeng  Farnsworth  Alexander  Valdes  Paul J.  Reichgelt  Tammo  Chen  Linlin  Zhou  Zhekun  Su  Tao 《中国科学:地球科学(英文版)》2022,65(7):1339-1352

Science China Earth Sciences - The growth of the Qinghai-Tibetan Plateau (QTP) during the Cenozoic drove dramatic climate and environmental change in this region. However, there has been limited...  相似文献   

Pressure calibration and sound velocity measurement to 12 GPa in multi-anvil apparatus     

Song  Wei  Shan  Shuangming  Tang  Qizhe  Su  Chang  Liu  Yonggang 《中国地球化学学报》2021,40(4):525-531

We performed the pressure calibration to 12 GPa for 14/6 type (octahedron edge length/WC truncated edge length, in mm) cell assembly in DS 6 × 1400 multi-anvil apparatus by using the phase transitions in Bi (I-II 2.55 GPa, III-V 7.67 GPa) and ZnTe (LPP-HPP I 9.6 GPa, HPP I-II 12.0 GPa). As verification and application, sound velocity measurements on polycrystalline Al₂O₃ to 12 GPa at room temperature were conducted and the ultrasonic result is in good agreement with previous reports. It demonstrates the feasibility of performing sound velocity measurements close to the mantle transition zone pressure condition in our laboratory.

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利用微区XRF技术测定地质样品中元素含量研究     

林梵宇  尹希杰  黄杰超  粟蓉  李云海  孙治雷 《矿物岩石》2021,41(4):59-67

微区XRF是新兴的固体样品表面元素半定量分析技术,由于缺少同类基质标样和仪器参数整体优化方案等问题,使得该技术在定量分析方面的研究较少.本研究利用微区XR F技术对黄铁矿地质标样硫、铁元素进行检测,探讨了真空度、驻留时间、检测器频率、X射线功率等仪器参数对非标定量准确度的影响,结果显示了真空度和X射线功率是影响检测准确度的重要指标,真空条件下,硫、铁元素检测结果与标样理论值的相对误差从非真空时的-52.25％和59.95％减少到0.51％和-0.21％;在20、30、40和50 keV的X射线功率下,硫元素的相对误差分别为-12.65％、-5.70％、-1.22％、0.51％,而铁元素分别为 14.79％、6.86％、1.76％、-0.21％.在优化的仪器参数下(检测器频率Tc设置为1 ps,驻留时间设置为100 s,X射线功率设置为50 keV,检测环境设置为真空),对土壤样品GSS-1进行非标定量,发现多数元素平行性良好,3次检测的相对标准偏差在3％以内;由于样品基质复杂,定量准确度较差,相对误差范围在-14.08％到905.98％之间.为优化准确度,采用GSS-2～GSS-10 土壤标样建立标准曲线,以标样GSS-1作为样品进行检测分析,结果显示通过线性校准曲线校正,GSS-1样品中多种元素检测值与理论值的相对误差减少到-13.07％到4.72％之间,而通过拟合标准曲线校正,相对误差在-13.64％到14.91％之间,两种标准曲线校正后全部元素的定量结果与理论值相对误差均在±15％之内.本研究结果表明,通过优化微区XRF测试参数,对黄铁矿简单基质样品可直接进行定量;对土壤基质复杂的样品,通过类似的基质标样建立相应标准曲线进行校准,也可获得准确度相对较好的定量结果.  相似文献   

Sequence stratigraphic characteristics and geological significance of the Permian Qixia Stage in northwestern Sichuan Basin          下载免费PDF全文

Hu Sheng  Tan Xiu-Cheng  Luo Bing  Zhang Ben-Jian  Zhang Ya  Su Cheng-Peng  Lu Fei-Fan  Li Ming-Long 《古地理学报》2021,22(6):1109-1126

Based on outcrops, drilling, cores, and logging data, the Liangshan Formation and Qixia Formation in the northwestern Sichuan region are analyzed using the theory and method of sequence stratigraphy. Three third-order sequence boundaries are identified, including the basal boundary of Liangshan Formation (type Ⅰ), the boundary between Qi 1 Member and Qi 2 Member (type Ⅱ), and the boundary between the Qixia Formation and the Maokou Formation (type Ⅰ). The Middle Permian Qixia Stage can be subdivided into two third-order sequences (from base to top: SQ1 and SQ2). The SQ1 sequence corresponds to the Liangshan Formation and the Qi 1 Member, and the SQ2 sequence corresponds to the Qi 2 Member. Based on the sequence stratigraphic framework reconstruction of the Qixia Stage, the sedimentary filling pattern of the “onlapping at the base and truncation at the top” is discovered. The contour maps of SQ1 and SQ2 sequence stratigraphic thickness are calculated and plotted. Combined with the stratigraphic filling pattern, the tectonic-palaeogeographical framework of the early SQ1 and SQ2 phases of the Qixia Stage, their geological significance is discussed. At the Qixia Stage, the differentiation between uplift and depression occurs in the northwest and northeast trends. The Hannan uplift, the northern Sichuan uplift, the northern margin uplift and the Guangyuan-Wangcang sag have controlled the sedimentary pattern in the study area. It is indicated that prototype of the Guangyuan-Wangcang Trough began in the Middle Permian Qixia Stage. In the study area, the karst cave-type dolostone reservoir and the karst-type limestone reservoir around the Guangyuan-Wangcang sag rim are favorable exploration areas.  相似文献