国内外侧扫声纳测量标准比较研究

由于侧扫声纳应用领域不断扩大,用户要求不断提高,国际海道测量组织和世界测量技术发达国家相继发布了各自的新版测量规范和标准。本文将我国侧扫声纳现行测量标准与国际相关标准在系统探测能力、测线布设、数据采集、质量控制等方面进行比较详细的分析比较,指出了我国侧扫声纳测量规范在测线布设、数据采集要求等方面的不足,旨在推进我国测量标准尽快实现与国际接轨。     

Geophysical Signature of the Shallow Water Flow in the Deepwater Basin of the Northern South China Sea

Shallow water flow (SWF), a disastrous geohazard in the continental margin, has threatened deepwater drilling operations. Under overpressure conditions, continual flow delivering unconsolidated sands upward in the shallow layer below the seafloor may cause large and long-lasting uncontrolled flows; these flows may lead to control problems and cause well damage and foundation failure. Eruptions from over-pressured sands may result in seafloor craters, mounds, and cracks. Detailed studies of 2D/3D seismic data from a slope basin of the South China Sea (SCS) indicated the potential presence of SWF. It is commonly characterized by lower elastic impedance, a higher Vp/Vs ratio, and a higher Poisson’s ratio than that for the surrounding sediments. Analysis of geological data indicated the SWF zone originated from a deepwater channel system with gas bearing over-pressured fluid flow and a high sedimentation rate. We proposed a fluid flow model for SWF that clearly identifies its stress and pressure changes. The rupture of previous SWF zones caused the fluid flow that occurred in the Baiyun Sag of the northern SCS.     

预修正快速傅里叶变换方法在波浪绕射和辐射问题中应用

在波浪对海上建筑物绕射和辐射问题的计算中,面元法被广泛使用,但由于传统面元法的存储量和计算量均为未知量的平方量级,很难满足大范围多未知量问题的计算需要。采用预修正快速傅里叶变换方法(pFFT方法),使计算量与存储量都降低到未知量的线性量级。以淹没圆球与漂浮圆柱两个典型算例为基础,通过不同未知量时pFFT方法与传统面元法的计算量与存储量的对比,以及pFFT方法自身各步骤计算时间的对比,研究了不同网格方案的选取对pFFT方法计算量和存储量的影响,推荐根据未知量个数采用计算时间最小化原则选取pFFT网格参数。     

GRS 1915+105的X射线能谱分析及黑洞自旋测量

GRS 1915+105是银河系内的低质量黑洞X射线双星,其能谱和黑洞自旋已经得到了广泛的研究.自2018年6月开始,其X射线流量下降到了低流量水平,其间偶尔会产生多波段的耀发.利用Insight-HXMT(Insight-Hard X-ray Modulation Telescope,简称为慧眼)卫星在2020年8月30日到2020年10月13日之间对GRS1915+105的观测数据,研究了其能谱特性,发现在此次爆发过程中, X射线能谱可以用一个康普顿化的多温黑体谱很好地拟合.整个爆发的硬度强度图(Hardness-Intensity Diagram, HID)一直处于软态.采用GRS1915+105的最新动力学参数M=12.4_-1.8^+2.0M⊙, i=60°±5°, D=8.6_-1.6^+2.0kpc (M、M⊙、i和D分别表示黑洞质量、太阳质量、盘倾角和距离),得到其无量纲黑洞自旋a*的一个下限a*> 0.9990,确认了GRS 1915+105是一个具有极端自旋的黑洞.考虑本地吸收体的...     

基于内存映射文件技术的海量VCT2.0数据库文件管理方法

讨论VCT2.0数据库文件的存储结构,研究Windows内存管理机制和内存映射文件技术的基本原理,实现内存映射文件技术存海量VCT2.0数据库文件管理上的应用,并完成性能分析.     

宁武盆地中-新生代构造演化的裂变径迹证据

为深入研究宁武盆地中-新生代的构造演化及煤层气资源的赋存条件,采集样品进行裂变径迹测试。锆石裂变径迹年龄为156～139 Ma,磷灰石裂变径迹年龄为97～47 Ma。宁武盆地中-新生代的构造演化历史可分为3个阶段。晚侏罗世(156 Ma),盆地两翼的岩体开始缓慢隆升,核部坳陷沉积,到早白垩世晚期(100 Ma),宁武盆地古地温达到最高,烃源岩达到了生气高峰期。白垩世晚期-古新世(79～59 Ma),快速抬升剥蚀。之后,虽有短暂埋藏,但总体处于隆升状态。渐新世晚期(40～30 Ma)以来快速抬升到现今位置。宁武盆地抬升剥蚀具有空间上的不均衡性。北东部抬升剥蚀早于南部,周缘岩体隆升剥蚀速率大于核部。宁武盆地是在中生代山西地块上形成一系列雁行状排列的复背斜和复向斜的构造背景下,新生代受印度洋板块挤压欧亚大陆,两翼山体强烈抬升推挤作用形成,属于华北克拉通区域构造事件的响应。     

基于蜂窝通信的突发事件预警短信靶向发布方案

短信因其传播方式的主动性、用户群体的广覆盖等特点,在突发事件预警信息发布中具有举足轻重的作用。但目前气象部门所建短信平台在发布时效、覆盖面、定位发布等方面存在局限性,无法满足预警信息快速、精准发布的要求。本文结合中国移动大数据平台,提出了基于蜂窝通信原理的突发事件预警短信靶向发布技术方案,并以该方案在宁夏地区的实现为例,重点阐述了系统布局、数据对接、目标用户筛选、靶向发布策略等关键技术。该方案可有效提高突发事件预警信息发布的针对性和有效性。     

Evaluating the spatiotemporal variations of water budget across China over 1951–2006 using IBIS model

The Integrated Biosphere Simulator is used to evaluate the spatial and temporal patterns of the crucial hydrological variables [run‐off and actual evapotranspiration (AET)] of the water balance across China for the period 1951–2006 including a precipitation analysis. Results suggest three major findings. First, simulated run‐off captured 85% of the spatial variability and 80% of the temporal variability for 85 hydrological gauges across China. The mean relative errors were within 20% for 66% of the studied stations and within 30% for 86% of the stations. The Nash–Sutcliffe coefficients indicated that the quantity pattern of run‐off was also captured acceptably except for some watersheds in southwestern and northwestern China. The possible reasons for underestimation of run‐off in the Tibetan plateau include underestimation of precipitation and uncertainties in other meteorological data due to complex topography, and simplified representations of the soil depth attribute and snow processes in the model. Second, simulated AET matched reasonably with estimated values calculated as the residual of precipitation and run‐off for watersheds controlled by the hydrological gauges. Finally, trend analysis based on the Mann–Kendall method indicated that significant increasing and decreasing patterns in precipitation appeared in the northwest part of China and the Yellow River region, respectively. Significant increasing and decreasing trends in AET were detected in the Southwest region and the Yangtze River region, respectively. In addition, the Southwest region, northern China (including the Heilongjiang, Liaohe, and Haihe Basins), and the Yellow River Basin showed significant decreasing trends in run‐off, and the Zhemin hydrological region showed a significant increasing trend. Copyright © 2009 John Wiley & Sons, Ltd.     

道路曲线数字化数据的联合平差模型

在讨论道路曲线基本单元数字化数据处理模型的基础上，进一步建立了道路曲线的联合平差模型，探讨了以线形为特征的交通运输空间数据的平差处理方法，提出了评价道路曲线数字化的精度指标。这些工作为研究交通空间数据的质量和建立动态分段模型以及道路GIS空间基础数据库是有益的。     

南海海平面高度年循环的特征

根据 ＴＯＰＥＸ／ ＰＯＳＥＩＤＯＮ－ＥＲＳ高度计提供的海平面高度异常资料和并行海洋气候模式（ＰＯＣＭ）模拟海平面高度资料，分析了南海海平面高度年循环特征。结果表明：ｌ月，３月和５月海平面高度的异常值分别与７月，９月，１１月的异常值相反。ｌ月（７月），深水海区与吕宋海峡的海平面高度为负（正）异常，在大部分陆架区和南海的西和南部，海平面高度为正（负）异常。在３月（９月），除海平面高度异常的量级已减少，且较小的ＳＳＨ正异常（负异常）出现在南海的中部以外，海平面高度异常的分布型与 １月（７月）类似； ＳＳＨ的年循环的最大振幅出现在吕宋岛的西北海域；风的季节变化是南海ＳＳＨ季节变化的主要原因。