水足迹与主成分分析法耦合的新疆水资源承载能力评价

通过耦合水足迹理论与主成分分析方法,构建基于水足迹的新疆地区水资源承载力评价指标体系,分析研究区2010～2015年间水资源承载能力变化情况.结果表明:2010～2015年间新疆地区的水资源承载力呈先增大后减小的现象,2014年水资源承载力最差,供水压力最大.其中,研究区的承载力主要受水资源和社会因素以及进出口贸易中虚...     

An Extreme Drought over South China in 2020/21 Concurrent with an Unprecedented Warm Northwest Pacific and La Ni?a

An extreme drought appeared in South China from October 2020 to March 2021. During that time, sea surface temperatures exhibited an unprecedented warm center over the northwest Pacific (NWP) and a cold center over the tropical eastern Pacific (La Ni?a). This study demonstrates the combined effects of an exceptionally warm NWP and a moderate La Ni?a are closely linked to the anomalous drought in South China. The sea surface temperature anomaly in these two regions induced a steeper horizontal geopotential height gradient over South China. As a result, anomalous northeasterly winds prevailed over South China, altering water vapor transport and moisture convergence. A simplified atmospheric general circulation model also verifies the influence of the NWP warm anomaly on South China precipitation. This study points out that the sea surface temperature variation in the NWP was important to the occurrence of extreme drought in South China from October 2020 to March 2021.     

捷联惯导与天文导航组合导航系统仿真研究

介绍了捷联惯导与天文导航(SINS/CNS)组合导航仿真方案,简要设计和实现了SINS/CNS组合导航软件仿真平台;以Kalman滤波为基础,通过将SINS和CNS所测得的飞行器相关姿态和位置信息进行数据融合,估计出组合导航系统的误差状态量,进而修正SINS的位置、速度和姿态,最后在该系统下进行仿真,验证了这种设计方案的可行性和有效性。     

台湾东北黑潮入侵东海陆架强度的变化规律:持续一年的ADCP现场流速观测

本文利用台湾东北陆坡附近海域持续一年的多普勒流速剖面仪(AcousticDopplerCurrent Profilers,ADCP)定点深水测流数据提取了观测站点处黑潮跨陆坡入侵强度的时间序列,并与美国海军混合坐标海洋模式(HybridCoordinateOceanModel,HYCOM)分析数据中提取的观测站点处以及台湾东北陆坡东西区段黑潮入侵强度的时间序列进行了对比研究。研究结果显示黑潮在观测站点处的跨陆坡入侵强度存在显著的季节和季节内变化特征,并且与台湾东北黑潮主轴位置的摆动有较好的对应关系,黑潮主轴东(西)移,则黑潮在台湾东北陆坡西段及观测站点处的入侵显著减弱(增强),而在台湾东北陆坡东段的入侵显著增强(减弱)。此外,观测站点处黑潮跨陆坡入侵强度的时间序列还显示出较强的10d和20d左右的短周期信号,其中10d的周期信号对应着东海黑潮斜压不稳定波动的特征周期,而20d的周期信号则体现了台湾东北附近海域局地涡旋的短期变化。     

喀斯特关键带水—土—气CO2分压垂直转化特征及影响因素

喀斯特关键带是碳循环在岩石圈、大气圈、水圈和生物圈的主要综合作用区域,各层相互作用形成不同的反应体系,其中,CO₂扮演了十分重要的作用。通过对双河洞洞穴上覆土壤及洞穴水及空气CO₂浓度的监测,采用数理统计分析方法,根据碳酸平衡系统理论对CO₂的垂直向转化特征进行系统分析。结果表明：CO₂的垂直向转化过程受洞穴内外部气温变化、滴水pH及脱气沉积过程的影响,其供给来源、离子饱和状况在雨季和旱季存在明显差异;雨季时,大气降水在土壤中下渗速度较快,构成一个相对稳定的封闭环境,土壤、表层喀斯特带对渗透水CO₂补充作用较弱,渗透水中CO₂分压（即PCO₂）变化范围在0.035~0.126 vol%,洞内水—气CO₂分压（△lg PCO₂ > 0）,洞穴水具有溶蚀性,此时表层喀斯特带下部中的CO₂应为洞穴水CO₂的主要来源;旱季时,由于降水量较小,渗透水有充分时间接受土壤与表层喀斯特带CO₂补充,构成开放系统,渗透水变化范围为0.038 vol%~0.095 vol%,更有利于发生先期沉积过程（PCP）,此时洞内空气PCO₂小于洞穴水（△lg PCO₂ < 0）,促使滴水在洞内再次发生沉积、形成沉积物,此时土壤和表层喀斯特带均为洞穴水CO₂的主要来源。     

On the warm/cold regime shift in the South China Sea: Observation and modeling study

Remote sensing data sets and a high-resolution three-dimensional regional ocean model were utilized to investigate the shifting of warm/cold regime and the associated sea level variation in the South China Sea (SCS) during 2000–2003. Both the altimetry data and the model results showed an increase in the sea level (warm phase) followed by an abrupt decrease (cold phase) in the SCS during 2000–2003. Heat budget calculations performed with the model revealed excess heat advection from the western Pacific warm pool into the SCS during the warm phase than the cold phase. The warm phase, which occurred during La Niña episodes, resulted from the intrusion of abnormally warmer western Pacific water that increased the heat content and thus sea level in the SCS. The cold phase, which occurred during El Niño episodes, was triggered by a reduction in the net atmospheric heat flux followed by cold water advection into the SCS. Decrease in the rate of precipitation minus evaporation (P?E) also accounted for the falling of sea level during cold phase. The present study integrated the available remote sensing data and advanced numerical model to identify the time-dependent three-dimensional dynamic and thermodynamic forcing that are important in governing the warm/cold regime shift in the SCS.     

空间技术实现地心坐标的精度检测与分析

为评价GPS、VLBI、SLR三种空间技术确定地心坐标的实现精度，选择使用三种技术并置站上的坐标数据，在经历元统一、偏心改正和七参数转换之后，计算了这三种技术实现的参考架的转换参数，得到了任意两种技术地心坐标不符值的加权中误差，以此作为外符精度。经分析可知VLBI与GPS实现的地心坐标比SLR高一些，可达到毫米级。     

Comparative study to evaluate three ground-based optical remote sensing techniques under field conditions by a gas tracer experiment

Today, ground-based optical remote sensing (ORS) has become an intensively used method for quantifying pollutant or greenhouse gas emissions from point or area sources, and for the validation of airborne or satellite remote sensing data. In this study, we present the results of a release experiment using acetylene (C₂H₂) as a tracer gas, where three ORS techniques were simultaneously tested for two main purposes: (1) the detection of emission sources and (2) the quantification of release rates. Therefore, passive and active open-path Fourier transform infrared spectroscopy (OP-FTIR) and open-path tunable diode laser absorption spectroscopy (TDLAS) were applied and evaluated. The concentration results of the active ORS methods are compared to those estimated by a Lagrangian stochastic atmospheric dispersion model. Our results reveal that passive OP-FTIR is a valuable tool for the rapid detection and imaging of emission sources and the spatial tracer gas distribution; while with active OP-FTIR and TDLAS, C₂H₂ concentrations in the sub-ppm range could be quantified that correlated well with the concentration data obtained by our modeling approach.     

基于SIP的IP-PBX系统研究

会话初始协议的出现，为解决在多用户之间的多会话问题提出了一个简单有效的处理办法和一个基于会话初始协议的网络专用电话交换机的整体设计，主要包括网关、协议、驱动3大部分。     

基于惯导／天文高精度定姿方法

研究了利用惯性导航系统与天文导航系统进行组合定姿的方法,构造了惯导/天文组合导航系统的状态方程和量测方程;采用卡尔曼滤波技术设计了惯导/天文组合定姿算法.设计飞行器的典型飞行轨迹,通过数学仿真对该算法的有效性进行了验证.结果表明,天文导航能够有效地补偿惯性导航因陀螺漂移带来的误差,非常适用于飞行器的高精度定姿.