激光点云的隧道数据处理及形变分析     

黄帆  李维涛  侯阳飞  吴廷  王解先 《测绘科学》2019,44(5):132-137

针对目前隧道的变形监测多是通过经纬仪、水准仪以及全站仪对隧道断面进行观测完成,无法准确、有效地反映隧道整体变形的问题。研究了基于三维激光扫描点云的数据处理及形变分析方法,首先进行隧道断面椭圆拟合,然后利用拟合得到的椭圆参数进行断面长、短半轴形变分析,同时对隧道管片进行拟合以求得观片接头处变形,进而对隧道整体变形进行分析。实验表明,对实测的两期数据截取12个位置相同的断面,利用文中算法进行断面椭圆拟合和形变分析,统计结果显示两期数据拟合所得长、短半轴之差绝对值均小于3mm,且各断面整体形变参考点90%的变形小于3mm,结果充分证明本文介绍的数据处理方法的合理性及有效性,与传统方法相比优势明显,对地铁施工和运行阶段的隧道变形监测具有一定的指导和借鉴意义。  相似文献   

地震活动时间分布不均匀结构的多尺度检验分析          下载免费PDF全文

陈时军  贾庆华  马丽 《地震学报》2005,27(5):532-542

利用ldquo;非零导数显著性rdquo;检验方法, 分析了中国大陆东西部地区及青藏高原、新疆、东北、华北、华南以及台湾构造区内地震活动广义应变释放时间分布的不均匀结构. 结果表明,当广义地震应变指数eta;取较小值时,新疆、华南、东北以及台湾构造区地震活动自1970年以来总体上呈长期增强趋势, 而青藏高原与华北构造区则呈长期减弱的态势;在较小的时间窗宽情况下,各构造区均存在多尺度成丛特征,显示出地震活动在一定的尺度层次下的强弱交替现象. 但当该eta;取较大值时,除青藏高原与台湾构造区在某些尺度时间窗宽内存在某些时段趋势性变化外,其它各构造区广义地震应变释放时间分布均无统计学意义上的显著变化.   相似文献   

空间线要素综合算法的不确定性讨论   总被引：1，自引：0，他引：1  

雷伟刚  刘大杰  童小华 《测绘工程》2005,14(1):33-36

简述了几种曲线综合算法思路,从综合算法阈值的计算,综合算例数据等方面对综合算法及其不确定性进行了量化的评价,并进一步总结了综合算法不确定的各种表现.  相似文献   

湖沼相土K0值与微结构参数的关联性分析     

谢雪宁  赵瑞斌  张彦 《岩土工程技术》2011,25(3):128-132

土的静止侧压力系数K0是实际工程中经常需要用到的重要数据,影响土的静止土压力系数的主要因素就是土本身的性质。静止土压力系数是土的工程性质的一个重要指标,土的工程性质与土的微观结构联系紧密,土的许多工程性质可以从土的微观角度进行解释。通过研究静止侧压力系数K0与土的微观参数之间的关系,得出静止侧压力系数K0与微观参数中的等效直径、数量、形态比关联不大,而与圆度比较相关。  相似文献   

溴化锂水溶液的几个主要物性参数计算方程   总被引：10，自引：0，他引：10  

贾明生 《广东海洋大学学报》2002,22(3):52-58

通过对溴化锂水溶液物性的实测数据进行回归分析 ,提出了溴化锂水溶液的平衡方程及粘度系数、结晶温度、密度、定压比热容、比焓等物性参数计算方程。回归和归纳出的方程中最大的相对误差为6 42 % ,平均相对误差均不超过 1 3 6% ,能够满足双效溴化锂吸收式制冷循环热力计算和传热计算的要求  相似文献   

A study of housing typology and perceived age-friendliness in an established Hong Kong new town: A person-environment perspective     

《Geoforum》2018

Our study examines older people’s perceptions towards the urban environment and their spatial experiences through a person-environment perspective. We argue that Person-Environment (P-E) fit is critical to older people’s quality of life: positive environmental stimuli and personal adaptation competence have been held to influence this fit, and quality of fit will eventually affect interactions between older people and place. In a mixed-methods study, a context sensitive place audit was applied to a new town in Hong Kong, with a view to identifying strengths and weaknesses in the built environment and older people’s own strategies of living. Through 302 questionnaires and three focus groups with older participants, the results revealed high appreciation of outdoor spaces, transportation and social participation. The findings also indicate a strong association between housing typology and perceived age-friendliness. People accommodated in public housing estates tended to accord higher scores to their living environment although social exclusion was identified among oldest-old respondents in particular. Older people’s affective links with their living environment across time and their unique life-course experiences may help to explain their relatively relaxed attitudes when they face changes and hardships.  相似文献   

北斗系统精密卫星钟差精度评价   总被引：1，自引：1，他引：0  

周佩元  杜兰  方善传 《测绘科学》2015,(12):86-90

针对目前北斗卫星导航系统尚未形成统一的事后轨道和钟差产品的现状,该文提出了一种较为全面的北斗卫星导航系统精密卫星钟差精度评价方法,从钟差拟合残差标准差和天跳变等方面对北斗系统事后精密卫星钟差的精度进行了评价。使用相同方法对2013年全年、2014年上半年的北斗系统精密卫星钟差产品进行了评价,以此来分析定轨策略调整对卫星钟差的影响。结果表明,武汉大学分析中心解算的北斗系统精密卫星钟差产品的精度为分米级,大部分卫星的钟差精度优于0.2m,且定轨策略调整后倾斜地球同步轨道/中地球轨道卫星钟差产品的精度有小幅度提升;定轨策略调整前卫星钟差天跳变在0.2~0.5m间,但是调整后钟差天跳变显著增大,变化范围为2~3m,建议在实际应用中对其加以慎重处理。  相似文献   

最小二乘拟合GNSS位置时间序列分析     

冯胜涛  刘雪龙  王友 《测绘科学》2015,(10):157-160

针对GNSS位置时间序列包含的线性趋势及其变化可能干扰后续分析并掩盖动力学因素信息的问题,该文使用最小二乘方法分析时间序列的线性趋势并减弱时间序列中阶跃的影响。分析了最小二乘方法用于GNSS位置时间序列分析的可行性及利用该方法分别获取趋势变化点前后的线性趋势,据此估计时间序列趋势变化的大小进而可以对时间序列进行修复。该方法用于GNSS位置时间序列的初步分析,可以方便有效地去除线性趋势变化对后续时间序列分析的影响,同时拟合结果本身也能反应出时间序列的变化特征。  相似文献   

Antarctica‐Australia fit resolved by satellite mapping of oceanic fracture zones     

J. J. Veevers 《Australian Journal of Earth Sciences》2013,60(2):123-126

Sea floor spreading between Antarctica and Australia was resolved into two stages: (1) fast (27 mm/year), from the present to 49 Ma on a northerly azimuth constrained by well mapped fracture zones; and (2) slow (4.5 mm/year), from 49 Ma to break‐up at 96 Ma. A northwesterly azimuth was inferred by interpolation between the position of the continents at 49 Ma and the initial fit of the continents at break‐up at 96 Ma; during this stage, jumps to Australia of the spreading ridge west of the Spencer‐George V Fracture Zone were postulated to have transferred parts of the Australian Plate to Antarctica. Recently acquired satellite gravity trends confirm the inferred northwesterly azimuth and ridge jumps of the early spreading stage.  相似文献   

Time-series analysis of monthly rainfall data for the Mahanadi River Basin, India   总被引：1，自引：0，他引：1  

Janhabi Meher  Ramakar Jha 《寒旱区科学》2013,5(1):0073-0084

Time series analysis has two goals, modeling random mechanisms and predicting future series using historical data. In the present work, a uni-variate time series autoregressive integrated moving average (ARIMA) model has been developed for (a) simulating and forecasting mean rainfall, obtained using Theissen weights; over the Mahanadi River Basin in India, and (b) simulating and forecasting mean rainfall at 38 rain-gauge stations in district towns across the basin. For the analysis, monthly rainfall data of each district town for the years 1901-2002 (102 years) were used. Theissen weights were obtained over the basin and mean monthly rainfall was estimated. The trend and seasonality observed in ACF and PACF plots of rainfall data were removed using power transformation (α=0.5) and first order seasonal differencing prior to the development of the ARIMA model. Interestingly, the ARIMA model (1,0,0)(0,1,1) 12 developed here was found to be most suitable for simulating and forecasting mean rainfall over the Mahanadi River Basin and for all 38 district town rain-gauge stations, separately. The Akaike Information Criterion (AIC), goodness of fit (Chi-square), R 2 (coefficient of determination), MSE (mean square error) and MAE (mea absolute error) were used to test the validity and applicability of the developed ARIMA model at different stages. This model is considered appropriate to forecast the monthly rainfall for the upcoming 12 years in each district town to assist decision makers and policy makers establish priorities for water demand, storage, distribution, and disaster management.  相似文献