近景摄影测量支持下的地铁盾构管片姿态测量方法及其应用

传统的地铁盾构管片姿态测量的方法存在作业时间长,与施工流水线交叉作业劳动量大,且无法实时测量等不足。本文提出了利用近景摄影测量的方法对盾构管片姿态进行测量,通过在盾构管片环上铺设人工标志点,使用数码相机进行拍摄,利用光束法平常对摄影图片进行数据解算,得到解算标志点坐标后,再根据空间三点定圆心原理确定盾构环圆心点的坐标。试验结果表明,对比传统测量方法,新方法误差不超过3 cm,能够完全满足盾构管片姿态的测量精度要求,具有很好的推广价值。     

大动态宽带干涉式雷电测向接收机新技术

提出了一种基于非线性盲辨识的自适应数字接收机技术。由于宽带雷电信号的时频特征未知或时变,在频域对宽带数字接收机输出信号中的谐波与互调分量进行识别和分选,并以其短时能量最小化作为其非线性行为模型参数的盲辨识准则,利用最速下降算法实现模型参数的自适应提取和更新,然后在线实时地对接收机输出信号进行非线性补偿。实验结果表明,该盲辨识数字接收技术可以将整机的无杂散失真动态范围（SFDR）提高近20dB,极有利于在强干扰存在时对微弱信号的接收与检测。     

Floodplain Residents' Preferences for Water Level Management Options in Flood Control Projects in Bangladesh

A maximum difference conjoint (MDC) model was part of a questionnaire toassess floodplain residents' preferences for the outcomes of water level managementinside an enclosed embankment system on the left bank of the Dhaleswari River, calledthe Compartmentalization Pilot Project (CPP)-Tangail. The outcomes were described as(a) varied flood depths in the rice field, (b) incidence of flooding on the courtyard andinside homes, (c) changes in floodplain and culture fisheries, and (d) varied conditionsof drainage congestion. Following a standard survey, the respondents from inside andoutside a completed section of the compartment (Cluster 1b) were shown profiles of these flood management outcomes and were asked to indicate for each profile the one most preferred and the one least preferred item. The results of the study indicated that the respondents had a clear preference for preventing flooding of their homes and courtyards and for an ideal water depth of 2 ft in the aman rice fields. At the same time, they also showed a strong concern about malfunctioning of sluices and to a lesser extent about the changes in the fish habitat. The successful application of the MDC as an approach to model tradeoffs among rural residents of Bangladesh shows that a relatively complex quantitative survey method, incorporating choice cards as pictograms, can be applied successfully even in a developing country.     

裂谷盆地构造热演化的数值模型及在南海北部的应用

在沉积盆地的定量模拟研究中,建立各种数值模型是研究的基础。由于裂谷盆地在科学研究和油气勘探上的重要性,对其数值模型的研究一直受到高度重视,提出了众多理论模型。本文选择影响较大的或对南海被动陆缘研究有重要作用的数值型进行介绍,包括最基础的McKenzie瞬时拉伸模型,以及后来发展起来的限时拉伸模型、单剪伸展模型、挠曲悬臂梁模型、伸展随深度变化的模型和多幕拉伸模型。重点介绍各个模型的基本假设、应用条件、盆地演化的数学表达式,分析各模型之间的异同点和相互关系。文中还列举了南海北部的一些研究实例,以帮助深入理解不同数值模型的方法和应用。     

AN EVALUATION OF SEVERAL TURBULENCE SCHEMES FOR THE PREDICTION OF MEAN AND TURBULENT FIELDS IN COMPLEX TERRAIN

A prognostic three-dimensional mesoscale model has been developed andused in one- and two-dimensional modes to evaluate ten local turbulenceclosure schemes. The schemes ranged from first-order to the two-equationprognostic schemes. Predictions by the models were compared for aone-dimensional convective boundary layer using mixed layer scaling andmeasurements to interpret the results. Two-dimensional simulations were alsoperformed for a sea-breeze flow and for flow over a hill. The results showedthat for all of the models considered, minor differences were produced in themean meteorological fields and in the vertical scalar fluxes, but majordifferences were apparent in the velocity variances and dissipation rate.Predicted tracer concentrations were very sensitive to the turbulence modelformulation for dispersion from a point source in the convective boundarylayer, particularly for the prediction of maximum concentrations. Predictedtracer concentrations from a surface volume source for the two-dimensionalsimulations were similar for all models, although the degree of mixing in themorning growth period produced some differences. Generally, good results forthe mean meteorological fields can be obtained with first-order schemes, evenif they underpredict the magnitude of turbulence in the convective boundarylayer, and reasonable tracer concentrations can also be obtained with thesemodels provided near-source effects are not important. The two-equationprognostic models performed best for the prediction of turbulence in theconvective boundary layer.     

试论中国城市化发展模式

结合城市化的新观念,提出了中国城市化发展新理论模式--中国城乡网络化发展模式.城乡网络化发展模式建立在区域综合协调发展基础之上,指的是在一定区域范围内城乡之间各种经济活动主体构成一个有序化的关联系统及其运行过程,并通过这个过程获得一种特有的网络组织功能效应.同时,还在此理论基础上针对我国东部、中部、西部地区各自的现实条件,分别对其实施城乡网络化发展进行了初步构想.     

On the multivariate total least-squares approach to empirical coordinate transformations. Three algorithms

The multivariate total least-squares (MTLS) approach aims at estimating a matrix of parameters, Ξ, from a linear model (Y−E _Y = (X−E _X ) · Ξ) that includes an observation matrix, Y, another observation matrix, X, and matrices of randomly distributed errors, E _Y and E _X . Two special cases of the MTLS approach include the standard multivariate least-squares approach where only the observation matrix, Y, is perturbed by random errors and, on the other hand, the data least-squares approach where only the coefficient matrix X is affected by random errors. In a previous contribution, the authors derived an iterative algorithm to solve the MTLS problem by using the nonlinear Euler–Lagrange conditions. In this contribution, new lemmas are developed to analyze the iterative algorithm, modify it, and compare it with a new ‘closed form’ solution that is based on the singular-value decomposition. For an application, the total least-squares approach is used to estimate the affine transformation parameters that convert cadastral data from the old to the new Israeli datum. Technical aspects of this approach, such as scaling the data and fixing the columns in the coefficient matrix are investigated. This case study illuminates the issue of “symmetry” in the treatment of two sets of coordinates for identical point fields, a topic that had already been emphasized by Teunissen (1989, Festschrift to Torben Krarup, Geodetic Institute Bull no. 58, Copenhagen, Denmark, pp 335–342). The differences between the standard least-squares and the TLS approach are analyzed in terms of the estimated variance component and a first-order approximation of the dispersion matrix of the estimated parameters.     

都市水源区村域社会−生态系统脆弱性空间分异的地理影响模式——以上海市青浦区为例

以上海市青浦区为例,采用数据包络模型、空间自相关模型、多元Logistic回归模型、地理探测器和层次聚类模型分析该区184个行政村社会?生态系统脆弱性的空间差异及地理影响机制。研究表明：① 基于熵权集结交叉的“投入?产出”效率模型对村域社会?生态系统脆弱性评价结果更具可信度和精确性,2018年行政村社会?生态系统脆弱性空间上呈由东向西逐渐降低的变化趋势,脆弱性均值为0.583;② 地理因素对经济发达村域社会?生态系统脆弱性空间分异仍旧具有重要影响。距上海市中心距离、距淀山湖距离、距青浦区中心距离和水域面积成为影响该区社会?生态系统脆弱性的4种主导地理因素,其地理影响力呈现系统结构空间差异和种类属性替代及程度转化;③ 依据地理因素影响力聚类分析将该区社会?生态系统脆弱性地理因素空间耦合模式分为10种,多地理因素耦合模式是主要决定类型,呈现中部多因素主导和两侧单因素主导并存的多元环状地域决定格局;针对不同类型提出调控区域社会?生态系统脆弱性的可行方式。     

机载激光雷达数据的建筑物三维模型重建

机载激光雷达技术可以快速获取建筑物高精度高密度的三维空间信息.文章提出一种建筑物三维模型重建方法,该方法利用栅格数据使用RANSAC算法提取建筑边界上的长线段,采用规则化策略获取建筑轮廓;在模型生成阶段,基于原始点云和屋顶拓扑关系约束,获取屋顶间的交线和交点,并结合已得到的建筑边界、屋顶间交线和交点获取三维建筑模型.实验结果表明,该方法思路清晰、科学可行且适用性强,提取的建筑边界和模型垂直精度高.     

Numerical simulations for coupled rock deformation and gas leak flow in parallel coal seams

Based on the new viewpoint of interaction mechanics for solid and gas, gas leakage in parallel deformable coal seams can be understood. That is, under the action of varied geophysical fields, the methane gas flow in a double deformable coal seam can be essentially considered to be compressible with time-dependent and mixed permeation and diffusion through a pore-cleat deformable, heterogeneous and anisotropic medium. From this new viewpoint, coupled mathematical models for coal seam deformation and gas leak flow in parallel coal seams were formulated and the numerical simulations for slow gas emission from the parallel coal seams are presented. It is found that coupled models might be close to reality. Meanwhile, a coupled model for solid deformation and gas leak flow can be applied to the problems of gas leak flow including mining engineering, gas drainage engineering and mining safety engineering in particular the prediction of the safe range using protective layer mining where coal and gas outbursts can efficiently be prevented. This revised version was published online in July 2006 with corrections to the Cover Date.