Environmental dependence of stellar mass,SFR, and SSFR for the Luminous Red Galaxy (LRG) sample of the SDSS DR7

Using the Luminous Red Galaxy (LRG) sample of the Sloan Digital Sky Survey Data Release 7 (SDSS DR7), we investigate the environmental dependence of stellar mass, star formation rate (SFR) and specific star formation rate (SSFR) of LRGs. It is found that stellar mass of LRGs nearly is independent of local environments, and that the environmental dependence of SFR and SSFR in the LRG sample is much weaker than the one in the Main galaxy sample. One possible explanation is that galaxy color and morphology are a pair of galaxy properties most predictive of local environments, while LRGs are a group of galaxies that are likely to be luminous, red and of early types (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A new look at pulsar statistics — Birthrate and evidence for injection

We make a statistical analysis of the periodsP and period-derivativesP of pulsars using a model independent theory of pulsar flow in theP-P diagram. Using the available sample ofP andP values, we estimate the current of pulsars flowing unidirectionally along theP-axis, which is related to the pulsar birthrate. Because of radio luminosity selection effects, the observed pulsar sample is biased towards lowP and highP. We allow for this by weighting each pulsar by a suitable scale factor. We obtain the number of pulsars in our galaxy to be 6.05_−2.80 ^+3.32 × 10⁵ and the birthrate to be 0.048_−0.011 ^+0.014 pulsars yr⁻¹ galaxy⁻¹. The quoted errors refer to 95 per cent confidence limits corresponding to fluctuations arising from sampling, but make no allowance for other systematic and random errors which could be substantial. The birthrate estimated here is consistent with the supernova rate. We further conclude that a large majority of pulsars make their first appearance at periods greater than 0.5 s. This ‘injection’, which runs counter to present thinking, is probably connected with the physics of pulsar radio emission. Using a variant of our theory, where we compute the current as a function of pulsar ‘age’ (1/2P/P), we find support for the dipole braking model of pulsar evolution upto 6 × 10⁶ yr of age. We estimate the mean pulsar braking index to be 3.7_−0.8 ^+0.8.     

The evolution of the z distribution of normal neutron stars in the Galaxy

Under the two initial 1‐D one parameter velocity distribution forms (one is normal, the other is exponential), the z direction scale height evolution of normal neutron stars in the Galaxy is studied by numerical simulation. We do statistics for the cases at different time segments, also do statistics for the cumulative cases made of each time segment. The results show in the cumulative cases the evolution curves of the scale heights are smoother than in the each time segment, i.e., the cumulation improve the signal‐to‐noise ratio. Certainly the evolution cases are different at different Galactic disk locations, which also have very large difference from the average cases in the whole disk. In the initial stages of z evolution of normal neutron stars, after the beginning transient states, the cumulative scale heights increase linearly with time, and the cumulative scale height increasing rates have linear relationship with the initial velocity distribution parameters, which have larger fluctuation in the vicinity of the Sun than in the whole disk. We utilize the linear relationship of the cumulative scale height increasing rates vs. the initial velocity distribution parameters in the vicinity of the Sun to make comparison with the observation near the Sun. The results show if there is no magnetic decay, then the deserved initial velocity parameters are obvious lower than the present well known results from some authors; whereas if introducing magnetic decay, for the 1‐D normal case we can make consistence among concerning results using magnetic decay time values which are supported by some authors, while for the 1‐D exponential case the results show the lackness of young pulsar samples in the larger z in the vicinity of the Sun (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

分形随机漫步噪声及相关函数

讨论了在地学、工程测量研究领域常见的随机漫步噪声,从理论上将经典布朗运动随机过程(随机漫步噪声)推广到分形布朗运动随机过程,并导出分形布朗运动随机过程的相关函数。     

2014秭归4.5、4.7级地震前小震活动特征研究

2014-03-27、30湖北秭归4.5、4.7级地震前,震中区附近发生过多次微小地震活动。双差精定位显示,这些小震集中分布在仙女山断裂北段西边次级小断裂附近(区域一)和北端端部(区域二)。结合近场地震波谱分析和区域地质构造特征认为,区域一的微小震主要为浅表塌陷事件,区域二的多数为构造地震事件。将区域二15次ML1.2以上事件震源机制解参数统计结果与该地区3次4级以上主震震源机制比较显示,两者的节面走向均为NNW和NE,力轴(P轴和T轴)的方位与倾角也基本一致,总体上均与区域应力场方向基本一致,反映了两者受力方式具有一致性,但两者的破裂滑动方式有差异,可能与仙女山断裂受库水作用活化的影响有关。     

Statistical analysis of galaxy surveys – III. The non-linear clustering of red and blue galaxies in the 2dFGRS

We present measurements of the higher order clustering of red and blue galaxies as a function of scale and luminosity made from the two-degree field galaxy redshift survey (2dFGRS). We use a counts-in-cells analysis to estimate the volume-averaged correlation functions,     , as a function of scale up to the order of   p = 5  , and also the reduced void probability function. Hierarchical amplitudes are constructed using the estimates of the correlation functions:     . We find that (i) red galaxies display stronger clustering than blue galaxies at all orders measured; (ii) red galaxies show values of   S _p   that are strongly dependent on luminosity whereas blue galaxies show no segregation in   S _p   within the errors; this is remarkable given the segregation in the variance; (iii) the linear relative bias shows the opposite trend to the hierarchical amplitudes, with little segregation for the red sequence and some segregation for the blue; (iv) faint red galaxies deviate significantly from the 'universal' negative binomial reduced void probabilities followed by all other galaxy populations. Our results show that the characteristic colour of a galaxy population reveals a unique signature in its spatial distribution. Such signatures will hopefully further elucidate the physics responsible for shaping the cosmological evolution of galaxies.     

雅砻江流域主汛期降水长期预报的一种方法

本文使用天气学方法，从影响雅砻江区域主汛期降水量的长期预报有关因子出发，再运用数理统计方法反复筛选，仅取３个主要因子：西部青藏高原８个站冬春积温，北部冬季极涡面积指数，南部冬季印缅槽平均强度，建立逐步回归预报方程。结果显示：对主汛期６～９月降水量预报拟合准确率为１６／１７即约９４％。回归分析中发现：尽管西太平洋副热带高压对盆地西部降水有很大影响，盛夏且与高原积温有较密切相关，但由放大范围长时段的青藏高原积温，对于雅砻江区域主汛期降水量的影响超过西太平洋副热高压，因而在逐步回归过程中，副高因子仍被剔除．     

西北地区五城市大型水源地地下水流模型若干问题研究

西北地区五城市系指西安市、兰州市、乌鲁木齐市、西宁市与银川市。五城市在“七五”期间分别建立了大型水源地的地下水管理模型，而地下水流模型的建立则是制作地下水管理模型的基础。一个好的地下水流模型对概化的水文地质模型必须有高度的仿真性，通过拟合求参必须有足够的保真性，对于预测必须有可靠性。     

高精度高空风预报技术探讨

针对航天气象保障中高分辨率高空风的预报需求,利用欧洲数值预报、GRAPESGFS、导航探空数据,通过WRF模式直接输出、高空风模式产品融合、动力统计订正等方法实现了20 km以下逐250 m的高空风短期预报,并选择2019年11月—2020年3月进行试验,结果表明：U风预报好于V风;5～14 km高空风预报效果好于其它层次;在模式产品融合基础上进行的动力统计订正,预报效果最好,对于同层U、V风,4 m/s偏差内预报准确率为77.4%,6 m/s偏差内预报准确率为93.2%。     

克拉玛依夏季日最高气温与08时 850hPa温度的关系

根据克拉玛依40年气温观测资料,分析克拉玛依夏季日最高气温与08时850hPa温度的关系,寻找预报夏季日最高气温关键因子.