老旧防空洞探测方法与分析

老旧防空洞是一种隐埋于地下几米到几十米的人防设施,一般的仪器无法从地表对其准确定位。本文利用地球物理勘探微重力测量和瞬变电磁测量两种方法,分别对已知参数防空洞进行探测,通过和已知防空洞的参数进行对比,总结出了微重力探测老旧防空洞的有效方法。     

GEDO IMS系统在有砟铁路精测中的应用

由于有砟铁路的精测工作效率与精度要求极高,常规人工测量手段精度低,轨道几何状态测量仪的测量速度慢,无法满足有砟铁路的捣固进度。本文介绍了GEDO IMS系统的工作原理,并重点对其应用于有砟铁路的精测效率和精度,以及联合大机捣固作业作全面测试。     

Conversion of Pressure to Depth for Moored Instruments Using a Reference Bottom Mounted Pressure Sensor

A new method is proposed to convert pressure measured by an instrument to water depth using an additional available bottom-moored pressure sensor. A perturbation analysis is used in this analysis, which leads to a simple formula for calculating water depth (defined as one from the mean sea surface to the instrument) from the pressure data. In field experiments, this method is easier to apply than existing methods. Based on the theoretical derivation, the error associated with the method comes from two sources when the instrument depth is known at the beginning of the measurement: temporal variation of deep water density at depths deeper than the instrument and variation in the gravitational acceleration with instrument displacement. These two sources contribute up to 4% of the error relative to the vertical displacement of the instrument, assuming the pressure sensor is accurate. With the vertical displacement of the instrument being on the order of 10?m, the absolute error is on the order of 0.4?m, which is expected and acceptable in oceanic measurements. The method is applied to data from a field experiment that took place along the Myanmar coast in December 2012.     

国家速滑馆动态高精度施工测量关键技术及应用

国家速滑馆建筑结构在空间上的不规则性、多样性、复杂性及超大规模给施工测量带来较大的难度,因此,加强对动态高精度测量技术的研究和应用,是实现施工过程各专业、各环节高精度搭接的重要基础。国家速滑馆动态高精度施工测量关键技术解决了不均匀作用力下大跨度马鞍形索网同步张拉困难的技术难题;突破了特大异形柔性结构屋顶预制、安装和调控精密测量关键技术,实现了精密工程测量从静态到动态、离散到连续的转变;形成了模型驱动的一测多用高密度网状排管表观形态高效测量新方法;解决了受阻或封闭环境长距离连续面超高精度地坪标高测量难题,有效指导了施工作业,为2022年冬奥会速滑项目的开展提供了保障。     

高水头泄洪底孔水力学研究方法适宜性分析

水力学问题研究方法多样且各具特点,各类方法所获成果的异同性倍受关注。基于某水电站高水头泄洪底孔,应用物理模型试验、水力学原型观测及时均化的紊流数学模型对水力学问题进行模拟或观测,辨识出3种研究方法的适宜范围及程度,三者对于宏观水力流态、底流速、时均压力及掺气空腔的模拟成果吻合良好,水面线模拟有一定差异,原型水面波动、水舌纵向扩散更大,成果可引导此类型水力学问题的研究方法选择及成果修正。     

Tectonic Stress State Changes Before and After the Wenchuan Ms 8.0 Earthquake in the Eastern Margin of the Tibetan Plateau

Crustal tectonic activities are essentially the consequences of the accumulation and release of in situ stress. Therefore, studying the stress state near active faults is important for understanding crustal dynamics and earthquake occurrences. In this paper, using in situ stress measurement results obtained by hydraulic fracturing in the vicinity of the Longmenshan fault zone before and after the Wenchuan Ms 8.0 earthquake and finite element modeling, the variation of stress state before and after the Wenchuan Ms 8.0 earthquake is investigated. The results show that the shear stress, which is proportional to the difference between principal stresses, increases with depth and distance from the active fault in the calm period or after the earthquakes, and tends to approach to the regional stress level outside the zone influenced by the fault. This distribution appears to gradually reverse with time and the change of fault properties such as frictional strength. With an increase in friction coefficient, low stress areas are reduced and areas with increased stress accumulation are more obvious near the fault. In sections of the fault with high frictional strengths, in situ stress clearly increases in the fault. Stress accumulates more rapidly in the fault zone relative to the surrounding areas, eventually leading to a stress field that peaks at the fault zone. Such a reversal in the stress field between the fault zone and surrounding areas in the magnitude of the stress field is a potential indicator for the occurrence of strong earthquakes.     

室内移动测量系统在新型基础测绘中的应用

室内移动测量系统在北京市新型基础测绘体系空间实体建设中发挥着重要作用。本文提出了室内移动测量系统在新型基础测绘体系空间实体建设中的技术框架,该框架包括室内外数据采集、处理流程与方法、多源点云数据拼接与融合及一体化点云和全景影像数据在全要素三维建模中的应用。并以NavVis M6室内移动测量系统为试验设备,选取怀柔区金隅水泥厂地区作为开展北京市新型基础测绘的试点区域。结果表明,本文室内移动测量系统作业流程可满足新型基础测绘体系空间实体建设的需求。     

专业村集聚的空间测度——以河南省专业村为例

调查了河南省487个专业村,形成了487×71的属性数据矩阵。通过GIS可视化、LISA集聚图分析,得出结论:(1)专业村数量明显增多,空间集聚程度显著增强;(2)特色农业型专业村早在20世纪80年代之前就已形成集聚态势,工业型专业村集聚始于20世纪90年代,服务业型专业村最晚,为21世纪以来逐渐形成;(3)受进入门槛、特定环境、农户市场意识等影响,三类专业村集聚成因有明显差异;(4)在较大区域尺度上,专业村集聚程度较高地域并非出现在经济发达区。     

Retrieval of aerosol optical properties over a vegetation surface using multi-angular,multi-spectral,and polarized data

An algorithm to retrieve aerosol optical properties using multi-angular,multi-spectral,and polarized data without a priori knowledge of the land surface was developed.In the algorithm,the surface polarized reflectance was estimated by eliminating the atmospheric scattering from measured polarized reflectance at 1640 nm.A lookup table （LUT） and an iterative method were adopted in the algorithm to retrieve the aerosol optical thickness （AOT,at 665 nm） and the （A）ngstr（o）m exponent （computed between the AOTs at 665 and 865 nm）.Experiments were performed in Tianjin to verify the algorithm.Data were provided by a newly developed airborne instrument,the Advanced Atmosphere Multi-angle Polarization Radiometer （AMPR）.The AMPR measurements over the target field agreed well with the nearby ground-based sun photometer.An algorithm based on Research Scanning Polarimeter （RSP） measurements was introduced to validate the observational measurements along a flight path over Tianjin.The retrievals were consistent between the two algorithms.The AMPR algorithm shows potential in retrieving aerosol optical properties over a vegetation surface.     

无人机磁矩测量方法

运载平台磁性分布研究和测量是平台选型与航磁设备加改装方案设计的前提与基础。通过无人机磁矩矢量分解及其磁场分量合成,提出一种基于总强度磁力仪的无人机磁矩测量方法,构建了相应的感应磁矩和固有磁矩计算模型,并通过实测数据的分析处理验证其有效性。