Magnetic hydrogen atmosphere models and the neutron star RX J1856.5–3754

RX J1856.5−3754 is one of the brightest nearby isolated neutron stars (INSs), and considerable observational resources have been devoted to it. However, current models are unable to satisfactorily explain the data. We show that our latest models of a thin, magnetic, partially ionized hydrogen atmosphere on top of a condensed surface can fit the entire spectrum, from X-rays to optical, of RX J1856.5−3754, within the uncertainties. In our simplest model, the best-fitting parameters are an interstellar column density   N _H≈ 1 × 10²⁰ cm⁻²  and an emitting area with   R ^∞≈ 17 km  (assuming a distance to RX J1856.5−3754 of 140 pc), temperature   T ^∞≈ 4.3 × 10⁵ K  , gravitational redshift   z _g ∼ 0.22  , atmospheric hydrogen column   y _H≈ 1 g cm⁻²  , and magnetic field   B ≈ (3–4) × 10¹² G  ; the values for the temperature and magnetic field indicate an effective average over the surface. We also calculate a more realistic model, which accounts for magnetic field and temperature variations over the NS surface as well as general relativistic effects, to determine pulsations; we find that there exist viewing geometries that produce pulsations near the currently observed limits. The origin of the thin atmospheres required to fit the data is an important question, and we briefly discuss mechanisms for producing these atmospheres. Our model thus represents the most self-consistent picture to date for explaining all the observations of RX J1856.5−3754.     

黄河落淤治理巨野煤田塌陷区可行性初探

巨野煤田自南向北呈条带状分布。北依黄河，南接万福河。洙水河、洙赵新河、郓鄄河、郓巨河等黄河支流倾斜穿过矿区，这为大面积利用黄河落淤治理沉陷地区提供了天然的运输河道和动力，通过合理疏通和开挖河道引流落淤并配合使用远距离输沙技术，将使巨野煤田恢复沃野千里成为可能。     

基于J2EE的数据通用性操作框架的研究与实现

数据操作是基于J2EE的多级应用开发中常见而又具有通用性的重要一部分，而框架技术的研究可以实现软件开发过程中的重用，提高软件开发效率和质量。通过对国内外成熟的开发框架进行研究，并综合各自的优点形成一套在开发中可以保证数据操作模块具有可重用、可扩展、稳定性好等优势的方案；同时结合电子政务中的一个应用实例给出了数据通用性操作框架技术在企业级开发中的具体实现。     

中国之雷雨

第一章雷雨之定义成因及分类第一节雷雨之定义降雨而同时有雷电现象者,谓之雷雨。故有雨,纵甚急暴,但若无闪电及雷声者,不得谓之雷雨;反之,如沙漠旋风、森林大火、火山爆发等,只有雷电交作而无雨者,亦不得称曰雷雨。但雷电现象,并非雷雨之因,实为雷雨之果,此可由下列事实证明之。 (一)一定高度间之电位差,全球各处几皆相等,然雷雨之数目与     

Non‐uniqueness of critical state line in compression and extension conditions

Experimental evidence has indicated that the critical state line determined from undrained compression tests is not identical to that determined from undrained extension tests. The purpose of this paper is to investigate a modelling method that accounts for the non‐uniqueness of critical state lines in the compression and the extension testing conditions. Conventional elastic–plastic cap models can predict only a unique critical state line for the compression and the extension tests. A new micromechanical stress–strain model is developed considering explicitly the location of critical state line. The model is then used to simulate undrained triaxial compression and extension tests performed on isotropically consolidated samples with different over‐consolidated ratios. The predictions are compared with experimental results as well as that predicted by models with kinematic hardening of yield surface. All simulations demonstrate that the proposed micromechanical approach is capable of modelling the undrained compression and the undrained extension tests. Copyright © 2009 John Wiley & Sons, Ltd.     

基于GIS的宁波市农业资源管理信息系统构建

对在农业资源管理中应用GIS技术的必要性进行了论述,在了解了宁波市农业资源环境的特点以及用户需求的基础上,利用GIS的二次开发技术,对宁波市农业资源管理信息系统进行了构建与开发.     

Wavelet analysis of satellite images for coastal watch

The two-dimensional wavelet transform is a very efficient bandpass filter, which can be used to separate various scales of processes and show their relative phase/location. In this paper, algorithms and techniques for automated detection and tracking of mesoscale features from satellite imagery employing wavelet analysis are developed. The wavelet transform has been applied to satellite images, such as those from synthetic aperture radar (SAR), advanced very-high-resolution radiometer (AVHRR), and coastal zone color scanner (CZCS) for feature extraction. The evolution of mesoscale features such as oil slicks, fronts, eddies, and ship wakes can be tracked by the wavelet analysis using satellite data from repeating paths. Several examples of the wavelet analysis applied to various satellite images demonstrate the feasibility of this technique for coastal monitoring     

The fractal geometry of the surface ruptures of the 1999 Chi-Chi earthquake, Taiwan

The 1999 September 20 Chi-Chi earthquake is the largest seismic event which occurred in the island during the twentieth century. Available seismic data relative to this earthquake are of high quality, and surface ruptures identified as features associated to the Chelungpu fault can be clearly observed at the surface and precisely mapped. We calculated the fractal dimension ( D ) and b value of Gutenberg–Richter law for 6-month aftershocks of the Chi-Chi earthquake for the fault area, and find that the surface ruptures exhibit self-similar geometry only within specific ruler intervals. The D values of the surface ruptures reflect the fault slip and geometry at depth. More importantly, the small-size aftershocks seem more likely to occur within high D value and high b value areas, whereas small D value and small b value areas have a high potential for medium- and large-size aftershocks.     

内蒙古复杂地区地震勘探找煤效果

内蒙古新上海庙地区是煤田地质勘探的空白区，其地表为干旱、半干旱沙漠及黄土覆盖，属地震条件复杂地区。本次勘探在“三边”工作基础上，优化地震工程设计，共布设地震测线16条。经充分实验，确定了激发参数及接收参数。根据勘探区地震地质条件横向变化大的特点，在处理中始终以三高为中心，以静校正、反褶积为重点，选择最佳处理流程及参数，基本控制了区内主要可采煤层赋存情况，并否定了原断距1700m的区域大断层一沙葱沟断层。