用全站仪测试九江长江大桥空间变位

文章介绍智能性全站速测仪在九江长江大桥荷载检定试验中的应用。与以往常用的挠度仅、水准仪等测量仪器相比，它具有测速快的优点，用于桥梁结构空间变位测试，精度可满足要求。

浅埋暗挖黄土地铁隧道施工地层空间变位分析

研究目的：为了解浅埋暗挖黄土地铁隧道施工地层空间变位规律，本文结合西安地铁二号线依托工程，构建三维数值计算模型，对黄土地区浅埋暗挖地铁隧道施工的地表、地层纵、横向变形规律进行系统研究，以期提高黄土地区地铁区间隧道的修筑水平。研究结论：（1）双洞开挖的空间效应与开挖洞径和相对位置有直接关系，后开挖洞室掌子面距先行洞室测试断面两倍洞径左右时开始产生影响，开挖洞室到先行洞室测试面断面时，影响最大；（2）浅埋暗挖法施工中地表地层沉降基本经历缓慢变化、急剧变化及逐渐平稳三个阶段；（3）施工对地层的影响与埋置深度近成反比关系，随地层深度逐渐增加，施工对另一侧地层的影响则逐渐减弱；（4）沉降速率与距离监测断面成反比关系，随掌子面向监测断面的靠近而不断增大，而后随着掌子面远离监测断面而不断减小，呈漏斗形，最大值在掌子面过后的2～4m的范围；（5）横向的地表沉降曲线呈宽底漏斗状，地层沉降曲线变为标准w形；（6）本文研究成果可为西安地铁修建中的地上地下重点文物和古今建筑的保护提供技术支持。

基于GNSS系统的大跨度悬索桥空间变位研究

大跨悬索桥梁的结构空间位置的变化与结构内力变化是一个统一体,桥梁结构空间状态的监测和对比分析是评估结构安全使用状态的重要组成部分。本文研究基于GNSS(全球导航卫星系统)实现对桥梁结构整体空间状态的监测,为悬索桥结构安全评估提供重要数据支撑。

浅埋暗挖黄土地铁隧道施工地层空间变位研究

随着我国经济的迅速发展，各大中型城市加快了地铁的建设步伐，地铁隧道施工越来越频繁。浅埋暗挖法做为地铁隧道的重要施工方法，对研究施工地层空间变位具有重要的意义，不仅能够提高施工的质量和效率，还能够保障施工的安全性，避免施工中坍塌等事故的发生。本文以西安地铁为例，研究浅埋暗挖法对黄土地铁隧道地层空间变位的影响。

基于监测数据的大跨径悬索桥主缆和主梁空间变位分析

作为大跨度悬索桥的主要承重构件,主缆及主梁的线形反映着结构整体的空间变位形态,是影响结构服役状态的重要评估指标。基于桥梁监测数据和定期空间变位几何观测数据,针对恒载状态主梁线形及主缆线形开展分析研究,通过对不同时间同一温度下主梁、主缆的恒载线形对比,评估一定时间段内桥梁结构空间变位情况。结果表明,该桥的主缆及加劲梁的线形及变形幅度一致性良好,为结构的安全评估及维护工作提供了基础。

Spatial variation law of vertical derivative zero points for potential field data

In this paper we deduce the analytic solutions of the first- and second-order vertical derivative zero points for gravity anomalies in simple regular models with single, double, and multiple edges and analyze their spatial variation. For another simple regular models where it is difficult to obtain the analytic expression of the zero point, we try to use the profile zero points to analyze the spatial variation. The test results show that the spatial variation laws of both first- and second-order vertical derivative zero points are almost the same but the second-order derivative zero point position is closer to the top surface edge of the geological bodies than the first-order vertical derivative and has a relatively high resolution. Moreover, with an increase in buried depth, for a single boundary model, the vertical derivative zero point location tends to move from the top surface edge to the outside of the buried body but finally converges to a fixed value. For a double boundary model, the vertical derivative zero point location tends to migrate from the top surface edge to the outside of the buried body. For multiple boundary models, the vertical derivative zero point location converges from the top surface edge to the outside of the buried body where some zero points coincide and finally vanish. Finally, the effectiveness and reliability of the proposed method is verified using real field data.

On Spatial Variability and Distribution of Soil Nutrients in Different Nitraria tangutorum Bobr.Populations in Tsaidam Basin

In this paper,six important distribution areas of Nitraria tangutorum Bobr.in Tsaidam Basin were selected as research objects,to study spatial variability and distribution of soil nutrients in different N.tangutorum populations and analyze the relationship between soil nutrient contents and geographical location,by measuring soil pH and the contents of organic matter（OM）,total nitrogen（N）,total phosphorus（P）,total potassium（K）,hydrolysis N,available P and available K in soils.Results showed that：（1） soil nutrient contents among different populations showed significant spatial variability,and soil depth had a significant effect on soil nutrients contents,but the variation rules were not obvious.（2）Average pH and average contents of OM,total N,total P,total K,hydrolysis N,available P and available K in soils with different depths（0-15,15-30,30-45 cm） varied in the range of 8.37-9.21,3.34-20.68,0.18-1.21,0.35-0.75,16.12-22.04,5.13-553.28,1.10-52.54 and 103.83-562.28 mg/kg,respectively.（3） The analysis results of correlation between average values of pH and contents of nutrient indexes in soils with different depths（0-15,15-30,30-45 cm） showed that the correlation of these indexes were different.（4）OM and total N contents in soils with different depths（0-15,15-30,30-45 cm） all had a significant positive correlation with latitude and negative correlation with longitude and altitude,and the correlation of available P and available K contents in surface soils（0-15 cm） with latitude,longitude and altitude were significant positive,significant negative and significant negative,respectively;moreover,longitude and latitude also showed a significant impact on soil available K contents with the depth of 30-45 cm.In addition,comprehensive analysis result of nutrient contents showed that N.tangutorum populations in Huaitou Tala Town had the highest fertility,and the fertility levels of N.tangutorum populations in Chaka Town and Wulan Keke Town were relatively lower.

Spatial Evolution and Locational Determinants of High-tech Industries in Beijing

Using datasets on high-tech industries in Beijing as empirical studies, this paper attempts to interpret spatial shift of high-tech manufacturing firms and to examine the main determinants that have had the greatest effect on this spatial evolution. We aimed at merging these two aspects by using firm level databases in 1996 and 2010. To explain spatial change of the high-tech firms in Beijing, the Kernel density estimation method was used for hotspot analysis and detection by comparing their locations in 1996 and 2010, through which spatial features and their temporal changes could be approximately plotted. Furthermore, to provide quantitative results, Ripley′s K-function was used as an instrument to reveal spatial shift and the dispersion distance of high-tech manufacturing firms in Beijing. By employing a negative binominal regression model, we evaluated the main determinants that have significantly affected the spatial evolution of high-tech manufacturing firms and compared differential influence of these locational factors on overall high-tech firms and each sub-sectors. The empirical analysis shows that high-tech industries in Beijing, in general, have evident agglomeration characteristics, and that the hotspot has shifted from the central city to suburban areas. In combination with the Ripley index, this study concludes that high-tech firms are now more scattered in metropolitan areas of Beijing as compared with 1996. The results of regression model indicate that the firms′ locational decisions are significantly influenced by the spatial planning and regulation policies of the municipal government. In addition, market processes involving transportation accessibility and agglomeration economy have been found to be important in explaining the dynamics of locational variation of high-tech manufacturing firms in Beijing. Research into how markets and the government interact to determine the location of high-tech manufacturing production will be helpful for policymakers to enact effective policies toward a more efficient urban spatial structure.

Influence of groundwater level change on vegetation coverage and their spatial variation in arid regions

Sampling and testing are conducted on groundwater depth and vegetation coverage in the 670 km2 of the Sangong River Basin and semi-variance function analysis is made afterwards on the data obtained by the application of geo-statistics. Results showed that the variance curve of the groundwater depth and vegetation coverage displays an exponential model. Analysis of sampling data in 2003 indicates that the groundwater depth and vegetation coverage change similarly in space in this area. The Sangong River Basin is composed of upper oasis, middle ecotone and lower sand dune. In oasis and ecotone, influenced by irrigation of the adjoining oasis, groundwater level has been raised and soil water content also increased compared with sand dune nearby, vegetation developed well. But in the lower reaches of the Sangong River Basin, because of descending of groundwater level, soil water content decreased and vegetation degenerated. From oasis to abandoned land and desert grassland, vegetation coverage and groundwater level changed greatly with significant difference respectively in spatial variation. Distinct but similar spatial variability exists among the groundwater depth and vegetation coverage in the study area, namely, the vegetation coverage decreasing (increasing) as the groundwater depth increases (decreases). This illustrates the great dependence of vegetation coverage on groundwater depth in arid regions and further implies that among the great number of factors affecting vegetation coverage in arid regions, groundwater depth turns out to be the most determinant one.

Phase Space Prediction of Chaotic Time Series with Nu-Support Vector Machine Regression

A new class of support vector machine, nil-support vector machine, isdiscussed which can handle both classification and regression. We focus on nu-support vector machineregression and use it for phase space prediction of chaotic time series. The effectiveness of themethod is demonstrated by applying it to the Henon map. This study also compares nu-support vectormachine with back propagation (BP) networks in order to better evaluate the performance of theproposed methods. The experimental results show that the nu-support vector machine regressionobtains lower root mean squared error than the BP networks and provides an accurate chaotic timeseries prediction. These results can be attributable to the fact that nu-support vector machineimplements the structural risk minimization principle and this leads to better generalization thanthe BP networks.

A fast-imaging method for airborne gravity gradient data based on tensor invariants

Airborne gravity gradient data contain additional short-wavelength information about the buried geological bodies.This study develops a fast interpretation method based on the gravity gradient data for the sources’spatial location and physical property parameters.This study analyzes the advantages of the source parameter inversion method based on tensor invariants.It proposes a normalized fast-imaging method based on tensor invariants to quickly estimate the spatial location parameters of sources through the local maximum value position of the imaging results.First,the tensor invariant characteristics and the imaging method’s effect in a simple model are analyzed using a theoretical model.Second,to analyze the imaging method’s application effect in complex model conditions,the method’s applicability is quantitatively analyzed using the data added with noise,superimposed anomalies of adjacent sources,and anomalies of deep and shallow geological bodies.The theoretical model’s simulation results show that the model’s imaging results in this study have satisfactory performance on the spatial position estimation of the sources.Finally,the method is applied to the gravity anomaly data corresponding to the Humble salt dome.The imaging results can effectively estimate the distribution of the salt dome’s horizontal and depths,verifying the practicability of the method.

Distribution Orientation and Driving Mechanism of Geographical Pattern Change of China′s Banking Industry

By analyzing the relationship among government, market driving forces, distribution orientation of banking industry, service opportunity equality and spatial patterns, this paper proposes that it is distribution orientation that lead to the formation and evolution of spatial pattern of banking industry. The difference of the distribution orientation leads to the separation of the spatial pattern of banking industry, and the change of the distribution orientation leads to the change of spatial pattern. The degree of spatial pattern change is subject to the degree of change of distribution orientation, and the scale of bank resources in the regions, which supports the distribution orientation variation. Based on these theoretical frameworks, some indicators were designed to analyze the pattern change of China′s banking industry and its effects since 1995 under the change of the distribution orientation. This paper finds that the orientation of economic benefit maximization driven by market causes the banking industry to concentrate in economically developed regions.The government, which does not follow the orientation of economic benefit maximization, plays a role of stabilizer. Since the bank branches in the regions with the greatest change in bank branch distribution are too few, and regions with the greatest change in bank loan allocation are the regions with lots of loans, the pattern change of the banking industry in physical form is not as notable as that in economic form.

The Role of Soil Investigation on Performance-based Design in Geotechnical Earthquake Engineering

The spatial variability of geotechnical earthquake engineering critical parameters obtained by laboratory and in situ tests in the same area is affected by different measurements. The paper provides a brief synthesis of ground motion and site effects analysis procedures within a Performance-Based Design framework. In particular it focuses about the influence on the evaluation of site effects in some active regions by different shear waves velocity measurements （Down Hole D-H and Seismic Dilatometer Marchetti Test SDMT）. Moreover the variation of shear modulus and damping ratio with strain level and depth from different laboratory dynamic or cyclic tests for soil characterisation （Resonant Column Test RCT） was evaluated. The available data enabled one to compare the shear waves velocity profile obtained by laboratory and in situ tests （Cone Penetration Tests CPT） with empirical correlations proposed in literature.

CONVERGENCE OF CASCADE ALGORITHMS AND SMOOTHNESS OF REFINABLE DISTRIBUTIONS

In this paper, the author at first develops a method to study convergence of the cascadealgorithm in a Banach space without stable assumption on the initial (see Theorem 2.1), andthen applies the previous result on the convergence to characterizing compactly supportedrefinable distributions in fractional Sobolev spaces and Holder continuous spaces (see Theorems3.1, 3.3, and 3.4). Finally the author applies the above characterization to choosing appropriateinitial to guarantee the convergence of the cascade algorithm (see Theorem 4.2).

Characterization of spatial variability with observed responses:application of displacement back estimation

Soil spatial variability is difficult to evaluate due to insufficient test data.An alternative option is estimation by indirect methods such as inverse analysis.In this paper,two examples are presented to demonstrate the capability and accuracy of the probabilistic estimation method to characterize soil spatial variability with displacement responses.The first example is a soil slope subject to a surcharge load,in which the spatially varied field of the elastic modulus is estimated with displacements.The results show that estimations based on horizontal displacements were more accurate than those based on vertical displacements.The accuracy of the estimated field was substantially reduced by increasing variance of elastic modulus.However,the estimation was generally acceptable as the error was not more than 10%,even for the high variance case(COV^l.5).The accuracy of estimation was also affected by the type of covariance function and the correlation length.When the correlation length decreased,the accuracy of estimation was reduced.The second example is a validation of laboratory model tests where a horizontal load was applied on a layered ground.The estimated thicknesses of soil layers were close to those in the real situation,which demonstrates the capacity of the estimation method.

Bonded excimer in stacked adenines:Semiclassical simulations

The nonradiative decay of a n-stacked pair of adenine molecules, one of which was excited by an ultrafast laser pulse, is studied by semiclassical dynamics simulations. This simulation investigation is focused on the effect of the formation of bonded excimer in stacked adenines on the mechanism of ultrafast decay. The simulation finds that the formation of the bond- ed excimer significantly lowers the energy gap between the LUMO and HOMO and consequently facilitates the deactivation of the electronically excited molecule. On the other hand, the formation of the chemical bond between two stacked adenines re- stricts the deformation vibration of the pyrimidine of the excited molecule due to the steric effect. This slows down the formation of the coupling between the HOMO and LUMO energy levels and therefore delays the deactivation process of the excited adenine molecule to the electronic ground state.