Optical identifications of five INTEGRAL hard X-ray sources in the Galactic plane

The results of optical identifications of five hard X-ray sources in the Galactic plane from the INTEGRAL all-sky survey are presented. The X-ray data on one source (IGR J20216+4359) are published for the first time. The optical observations were performed with the 1.5-m RTT-150 telescope (Turkish National Observatory, Antalya, Turkey) and the 6-m BTA telescope (Special Astrophysical Observatory, Nizhny Arkhyz, Russia). A blazar, three Seyfert galaxies, and a high-mass X-ray binary are among the identified sources.     

Migration of supermassive black holes in galactic nuclei

The migration of central black holes in galactic nuclei through their encounters with galactic globular clusters is studied. The black hole moves in the field of the galactic bulge with a fixed potential. The dependences of the black-hole drift amplitude on orbital parameters of the globular cluster, its mass, and bulge parameters have been found. The drift amplitude of the central black hole can reach several parsecs in our Galaxy and several tens of parsecs in early-type (Sa) and late-type (Sc) spiral galaxies.     

Dynamical Control of Asymmetrically Oblique Tidal Currents to the Sedimentary Characteristics and Development of Linear Sand Ridges in the Liaodong Shoal,East Bohai Sea

The Liaodong Shoal is a group of linear sand ridges located in the east Bohai Sea of China.In this study,54 surface sediment samples have been collected,current measurements at 4 stations have been carried out and bathymetric data were obtained.The current directions are rightward deflected relative to the strikes of the sand ridges.Affected by the narrowing effect of the ridge,the current velocities exhibited an anti-‘C’type vertical profile.The velocities of the lower currents linearly correlate with the water depths.The near-bed current velocities over the troughs are estimated to be higher than those over the ridges,and this feature could be explained by the loss of kinetic energy together with the conversion between kinetic energy and gravitational potential energy.The sedimentary characteristics that are compatible with the tidal dynamics are developed across the ridges and troughs,including grain size compositions,grain size parameters,mineral compositions and Dhm indexes.The existence of the angles between the current directions and the strikes of the sand ridges is the key factor for the growth of the sand ridges.The asymmetric hydrodynamic features between the flood and ebb currents lead to the differences in the topographical and sedimentary characteristics on both sides of a sand ridge.Insufficient material supply led to the degradation of the sand ridges,and the reduction of the tidal current intensity has led to the development of the subordinate sand ridges in the troughs.Sand ridges are migrating.     

Spatially filtered ridge regression (SFRR): A regression framework to understanding impacts of land cover patterns on urban climate

Understanding the impacts of land cover pattern on the heat island effect is essential for sustainable urban development. Conventional model fitting methods have restricted ability to produce accurate estimates of the land cover‐temperature association due to the lack of procedures to address two important issues: spatial dependence in proximal spatial units and high correlations among predictor variables. In this study, we seek to develop an effective framework called spatially filtered ridge regression (SFRR) to estimate the variations in the quantity and distribution of land surface temperature (LST) in response to various land cover patterns. The SFRR effectively integrates spatial autoregressive models and ridge regression, and it achieves reliable parameter estimates with substantially reduced mean square errors. We show this by comparing the performance of the SFRR to other widely adopted models using Monte Carlo simulation followed by an empirical study over central Phoenix. Results highlight the great potential of the SFRR in producing accurate statistical estimates, providing a positive step toward informed and unbiased decision‐making across a wide variety of disciplines. (Code and data to reproduce the results in the case study are available at: https://github.com/cfan13/SFRRTGIS.git .)     

冬季大范围持续性极端低温事件与欧亚大陆大型斜脊斜槽系统研究进展

本文总结了近年来关于我国冬季大范围持续性极端低温事件（EPECE）及其对应的欧亚大陆大型斜脊斜槽系统的研究成果。EPECE和普通寒潮是冬季影响我国的两类不同时间尺度大型冷空气活动,对它们的异同点进行梳理和深入理解是非常必要的。最新研究进展可概括为如下:（1）基于极端低温站点的范围和极端低温过程的持续性特点,客观界定了我国冬季EPECE。近年来的研究表明,欧亚大陆大型斜脊斜槽系统是冬季EPECE形成和维持的主要关键环流系统。同时,鉴于大型斜脊斜槽系统的重要应用意义,建立了客观识别方法。（2）从前兆信号、环流演变、阻塞高压和反气旋式波破碎活动的角度,揭示了EPECE和普通寒潮事件之间的关键区别。全国类EPECE的发生具有一周之前的前兆信号,而普通寒潮并不存在这么早的前兆信号。EPECE以从乌拉尔山到东北亚的广阔区域的阻塞高压活动为关键特征,而普通寒潮则主要以区域性阻塞高压为其主要特征。这两类事件对应的阻塞高压活动的差异可由天气尺度波破碎活动的差异加以解释。（3）最新的研究解释了大型斜脊斜槽系统形成和维持的动力学机理。基本流场对位涡扰动的正压作用是大型斜脊斜槽系统的形成和维持最重要的动力学机制。基本流场通过变形场作功和线性平流使大型扰动维持和向下游发展。与阻塞高压不同,非线性作用并非大型斜脊斜槽系统维持的主要原因。     

滇西洋拉矿区火山岩构造—岩浆类型

羊拉矿区的火山岩形成于石炭纪金沙江裂谷洋盆中段,其构造－岩浆类型有３：早石炭世羊拉岩组的富集型洋中脊拉斑玄武岩;晚石炭世里农岩组的洋岛钙碱性安山岩和洋岛碱性率武岩。各种构造－岩浆类型的形成均与地幔热性相关。     

Thermal structure and paleo-heat flow in the Shimanto accretionary prism, Southwest Japan

Abstract Thermal structural analysis and paleo-heat flow estimation provide clues to understanding the thermal evolution of the accretionary complex. The thermal structure and heat flow in the Jurassic Chichibu and Cretaceous to Tertiary Shimanto accretionary complex, Southwest Japan, have been investigated by vitrinite reflectance measurement and fluid inclusion analysis. As a result, the local and multistage metamorphisms were recognized as follows. First, the Tertiary complex around the Miocene Ashizuri granite underwent exposure to extra-high temperatures. Second, the Okitsu Melange underwent exposure to higher temperatures than the surrounding strata and was formed concurrently with the Kula-Pacific ridge subduction beneath the Japanese Islands in the Eocene. Finally, the thermal structure of most of the Cretaceous and southern Jurassic complexes is independent of the geologic structure, indicating that these areas suffered thermal overprint. Regional radiometric dating studies show that most of the Cretaceous Shimanto complex was heated in the Eocene; the thermal overprint might have occurred as a result of ridge subduction. The heat flow during peak heating was estimated to be 95–120 mW/m² except for the Cretaceous Okitsu melange and the Cretaceous Nonokawa formation, north of the Okitsu Melange; a much higher value of heat flow of ~200 mW/m² was estimated in the Okitsu Melange. An estimation of heat flow failed for the non-okawa formation because thermal equilibrium between the fluid and rocks has not yet been reached. It is probable that the southern strata underwent a higher heat flow. Such a trenchward increase in heat flow resembles the present situation of the Nankai Trough, although the heat flow in the Eocene was much higher.     

Architecture of a tide-influenced river delta in the Frontier Formation of central Wyoming, USA

The Frewens sandstone is composed of two elongate tide-influenced sandstone bodies that are positioned directly above and slightly landward of a more wave-influenced lobate sandstone. The 20-km-long, 3-km-wide Frewens sandstone bodies coarsen upwards and fine away from their axes, have gradational bases and margins and have eroded tops abruptly overlain by marine shales. These sandstones are superbly exposed in large cliffs on the banks of the South Fork of the Powder River in central Wyoming, USA. The deposits change upwards from thinly interbedded sandstones and mudstones to metre-thick heterolithic cross-strata and, finally, to metres-thick sandstone-dominated cross-strata. There is abundant evidence for tidal modulation of depositional flows; however, palaeocurrents were strongly ebb-dominated and nearly parallel the trend of sandstone-body elongation. Detailed mapping of stratal geometry and facies across these exposures shows a complex internal architecture. Large-scale bedding units within sandstone bodies are defined by alternations in facies, bed thickness and the abundance of shales. Such bedsets are inclined (5°–15°) in walls oriented parallel to palaeoflow and gradually decrease in dip over hundreds of metres as they extend from the sandstone-dominated deposits higher in a sandstone body to muddier deposits lower in the body. Where viewed perpendicular to palaeoflow, bedsets are 100-metre-wide lenses that shingle off the sandstone-body axis towards its margins. The sandstone bodies are interpreted as sand ridge deposits formed on the shoreface of a tide-influenced river delta. Metres-thick cross-strata in the upper parts of sandstone bodies resemble deposits of bars (sandwaves) formed where tidal currents moved across shallows and the tops of tidal ridges. Heterolithic deposits lower in sandstone bodies record fluctuating currents caused by ebb and flood tides and varying river discharge. Erosion surfaces capping sandstone bodies record tidal ravinement. The tidal ridges were abandoned following transgression and covered with marine mud as waters deepened.     

预处理共轭梯度法解病态问题及在GPS中的应用

介绍测量数据处理中病态问题的岭估计思想及确定岭参数的方法。引入预处理共轭梯度法求解病态法方程组,说明算法的基本原理和它能有效减弱病态性的原因。用一个GPS差分动态定位的实例,通过与不同岭估计方法的对比分析,验证该方法是一个有效的数值迭代算法。     

利用最优正则化方法确定Tikhonov正则化参数

基于均方误差最小意义下运用最优正则化方法确定正则参数,推导了计算最优正则参数的公式,并结合算例分析比较了求解病态方程的L-曲线法、GCV法等常用的方法,算例表明,基于最小均方误差的Tikhonov正则化参数优化选取方法是一种可行有效的方法。