The conversion from neutron stars to strange stars and its implications     

Zigao Dai  Xuejun Wu  Tan Lu 《Astrophysics and Space Science》1995,232(1):131-138

The conversion from neutron stars with different equation of states (EOSs) for neutron matter into strange stars with different EOSs for strange quark matter has been studied in a general relativistic numerical calculation in this paper. For hot neutron stars, their conversion may lead to great variations in their rotation periods, of which the magnitude would be greatly dependent upon the EOS for neutron matter, and of which the timescale would be greatly determined by the EOS for strange matter. This phenomenon appears as giant glitches, which might provide a probe of EOSs for both neutron matter and strange matter. But for cold neutron stars, their conversion may result in a population of gamma-ray bursts.  相似文献   

Decametric bursts caused by the fragment S of comet SL-9     

Xi-Zhen Zhang  Hong Wang  Jun-Hu Du  Zhi-Kai Wang 《Earth, Moon, and Planets》1994,66(1):49-52

On July 21, 1994, 13 ^h - 15 ^h UT, decametric bursts had been recorded at frequencies from 24.0 MHz to 28.5 MHz in Xin Xiang station (longitude =-113.8°, latitude =35.3°), Henan province, China. Three maps of the three hour data are presented. Some of the bursts appears to be relative to the impact of the fragment S(No. 5) of the comet SL-9.The Project is supported by the National Natural Science Foundation of China.  相似文献   

Experimental Evidence of Critical Sensitivity in Catastrophe     

Xianghong Xu  Mengfen Xia  Fujiu Ke  Yilong Bai 《Pure and Applied Geophysics》2006,163(9):1751-1767

The paper presents an experimental study on critical sensitivity in rocks. Critical sensitivity means that the response of a system to external controlling variable may become significantly sensitive as the system approaches its catastrophic rupture point. It is found that the sensitivities measured by responses on three scales (sample scale, locally macroscopic scales and mesoscopic scale) display increase prior to catastrophic transition point. These experimental results do support the concept that critical sensitivity might be a common precursory feature of catastrophe. Furthermore, our previous theoretical model is extended to explore the fluctuations in critical sensitivity in the rock tests.  相似文献   

The Displacement and Strain Field of Three-dimensional Rheologic Model of Earthquake Preparation     

Zhiping Song  Xiangchu Yin  Shirong Mei  Yucang Wang  Can Yin  Huihui Zhang  Langping Zhang 《Pure and Applied Geophysics》2006,163(9):1991-2009

Based on the three-dimensional elastic inclusion model proposed by Dobrovolskii, we developed a rheological inclusion model to study earthquake preparation processes. By using the Corresponding Principle in the theory of rheologic mechanics, we derived the analytic expressions of viscoelastic displacement U(r, t) , V(r, t) and W(r, t), normal strains ε_xx (r, t), ε_yy (r, t) and ε_zz (r, t) and the bulk strain θ (r, t) at an arbitrary point (x, y, z) in three directions of X axis, Y axis and Z axis produced by a three-dimensional inclusion in the semi-infinite rheologic medium defined by the standard linear rheologic model. Subsequent to the spatial-temporal variation of bulk strain being computed on the ground produced by such a spherical rheologic inclusion, interesting results are obtained, suggesting that the bulk strain produced by a hard inclusion change with time according to three stages (α, β, γ) with different characteristics, similar to that of geodetic deformation observations, but different with the results of a soft inclusion. These theoretical results can be used to explain the characteristics of spatial-temporal evolution, patterns, quadrant-distribution of earthquake precursors, the changeability, spontaneity and complexity of short-term and imminent-term precursors. It offers a theoretical base to build physical models for earthquake precursors and to predict the earthquakes.  相似文献   

LURR and the San Simeon M 6.5 Earthquake in 2003 and the Seismic Tendency in CA     

Yongxian Zhang  Xiangchu Yin  Keyin Peng  Haitao Wang  Jianchang Zheng  Yongjia Wu  Lang-ping Zhang 《Pure and Applied Geophysics》2006,163(11-12):2343-2351

The spatial and temporal variation of LURR (Load/Unload Respond Ratio) in California during April 2002 to June 2004 was studied in this paper. The result shows that before the San Simeon earthquake (35.7 N, 121.1 W) on Dec. 22, 2003, Y/Y _c anomalous region occurred successively near the epicenter from April 2002 to June 2002, and the maximum anomaly of Y/Y _c occurred in May, 2002. The published research work pointed out that the Y/Y _c anomaly near the San Simeon earthquake appeared from March, 2002. Compared with the five earthquake cases out of the six with M ≥ 6.5 in California during the period from 1980 to 2001, the maximum Y/Y _c and duration of Y/Y _c anomaly before this earthquake are among the normal ranges, but the time delay from the maximum anomaly time to the occurrence time of this earthquake is the longest one. The result also shows that two areas with Y/Y _c anomalies occurred from Oct. 2002 and Dec. 2002, respectively. According to statistical characteristics of the relationship between Y/Y _c anomalies and the coming earthquakes, the seismic tendency in California was discussed in this paper.  相似文献   

Reductive kinetics of the reaction between a natural ilmenite and carbon     

Yuming Wang  Zhangfu Yuan 《International Journal of Mineral Processing》2006

The reductive degree and rate of Bama ilmenite concentrate by graphite under argon atmosphere were measured by using thermogravimetric analysis system at the temperatures from 850 °C to 1400 °C. The reduction degree of the ilmenite increased with temperature rise, the case similar to reaction rate. The higher the temperature was, the faster the reaction rate was. The phases before and after reduction and the morphology of reduced samples were identified by using X-ray diffraction and optical microscopy analysis, respectively. The reduction degree of the ilmenite decreased due to the presence of impurities. Manganese and magnesium oxide-rich zones formed which prevented complete reduction of Fe²⁺. In general, the reaction products were iron, Ti₃O₅, reduced rutiles and pseudobrookite solid solution. The kinetics was also discussed and it was found that the rate-controlling steps were different in the different temperature ranges.  相似文献   

用动力相似方法预报广东省区域暴雨试验   总被引：4，自引：4，他引：4  

万日金  何溪澄  林钢 《热带气象学报》2006,22(2):198-202

应实际业务预报需要，利用最新43年欧洲中期数值预报中心（ECMWF）逐日再分析资料，采用多种动力相似方法研究了广东省短期区域暴雨预报，发现了预报员预报经验成长曲线模式，找到了影响暴雨预报的决定性因子850hPa风场，证明了双时次相似的优越性，并研制了广东短期区域暴雨预报的动力相似法，预报评分明显高于业务平均水平。该方法的应用软件实现了短期区域暴雨的自动、客观、定时、定点、定量预报，目前已经投入业务使用。  相似文献   

机载激光雷达数据的误差分析及校正   总被引：2，自引：2，他引：2  

王成  Menenti M  Stoll M p  李传荣  唐伶俐 《遥感学报》2007,11(3):390-397

数据质量分析是遥感机理/应用研究（尤其是定量遥感）首要和关键的一步,直接影响遥感反演的精度和遥感应用的效果。激光雷达（Light Detection and Ranging,LiDAR）是一种新兴的主动遥感技术,对数据后处理算法的研究还有待进一步加强,尤其对激光雷达数据的质量分析显得十分迫切。采用了一种基于扫描航带间重叠区数据分析的方法对LiDAR数据质量进行评价,分析误差来源,计算误差的大小,并分别对数据的随机和系统误差进行校正。以机载激光雷达数据为例来进行验证,实验结果表明,这种方法能有效地减少数据误差,达到提高数据质量的目的。  相似文献   

卫星观测方位对遥感成像的影响   总被引：2，自引：0，他引：2  

张云松  冯钟葵  石丹 《遥感学报》2007,11(4):433-438

光学卫星成像主要是通过传感器接收地表对太阳入射光线的反射、地表辐射和大气散射等能量,形成影像数据。卫星侧视成像时,太阳与卫星之间的位置关系随日期、地理位置和地方时变化,当条件适当时,两者处于对称关系,从地面上看类似镜面反射状态。此时,由于地表的非朗伯性,就使卫星接收的反射能量偏高,造成接收得到的图像亮度高于正常水平,甚至过饱和而不可用。本文以SPOT卫星为例,从卫星的观测方位和太阳的照射方位入手,讨论卫星观测方位对遥感成像质量的影响。经分析,每年5—9月期间,在北纬32°—45°地区,当SPOT卫星以较大的侧视角向左侧成像时,卫星观测方向和太阳入射方向在成像区投影共线并且太阳的高度角与卫星的高度角近似相等的可能性很大,从而影响卫星成像的质量。  相似文献   

SZ-4雷达高度计及其在轨测量结果     

许可  刘和光 《遥感学报》2007,11(4):439-445

SZ-4雷达高度计搭乘神舟4号飞船（SZ-4）于2002年12月30日发射入轨,按预定模式工作,获得了大量有效的观测数据。SZ-4雷达高度计是中国第一个上星工作的实验性海洋雷达高度计,为中国海洋动力环境卫星的发展奠定了基础。本文系统地论述了SZ-4雷达高度计系统方案、系统实现和在轨测量结果。  相似文献