Applied Mechanics and Materials Vols. 90-93

Abstract: Based on characteristic analysis of the aged people’s traveling and research for the development of the urban barrier-free traffic environments, the article analyses some factors of the barrier-free traffic environment, such as road barrier-free, vehicles barrier-free, information and communication barrier-free. In order to offer some good advice in the rapid development of Urban barrier-free environment.

Abstract: The drought resistance adaptation mechanism of highway greening plants was always the focal point which the researcher payed attention. This experiment took Cornus alba as the study object and examines its resistance to drought stress by using the potting and water control method. The researcher measured bond water content, water saturation deficit, relevant water content, relevant content of osmotic water, and osmotic potential when full turgor and turgor were both zero. Other water condition indexes also were analyzed systematically. Finally, a comprehensive evaluation on the drought resistance of Cornus alba by fuzzy mathematics’ anti-membership function was conducted. According to the experiment result, Cornus alba had the highest drought resistance at B-level treatment (soil water content: 53.60%), followed by D-level (soil water content: 29.90%) treatment. Cornus alba had strong endurance and resistance to drought stress. This study could provide a scientific basis for the future introduction of other urban greenbelt plants and the choice of excellent traits.

Abstract: A regularization homotopy iterative method established for ill-posed nonlinear least squares problem. Two new regularization parameter selecting strategies are proposed, which are called direct search method and interval division method. The calculation results of nonlinear least squares problems show that the regularization homotopy iterative method and parameter selecting strategies proposed in this paper are correctly and applicable. And also calculation results of nonlinear adjustment of free networks with rank deficiency of Jianglong bridge pier displacement defor-mation monitoring control network show that the method not only decrease the iterative matrix con-dition number, but also make the condition number small fluctuation in full iterative process.

Abstract: The foundation of delaunay triangulation and constrained delaunay triangulation is the basis of three dimensional geographical information system which is one of hot issues of the contemporary era; moreover it is widely applied in finite element methods, terrain modeling and object reconstruction, euclidean minimum spanning tree and other applications. An algorithm for generating constrained delaunay triangulation in two dimensional planes is presented. The algorithm permits constrained edges and polygons (possibly with holes) to be specified in the triangulations, and describes some data structures related to constrained edges and polygons. In order to maintain the delaunay criterion largely，some new incremental points are added onto the constrained ones. After the data set is preprocessed, the foundation of constrained delaunay triangulation is showed as follows: firstly, the constrained edges and polygons generate initial triangulations，then the remained points completes the triangulation . Some pseudo-codes involved in the algorithm are provided. Finally, some conclusions and further studies are given.

Abstract: Abstract.The wetlands dynamics was investigated in Nansi Lake for the period between 1987 and 2007. Four periods of remote sensing images, including TM&ETM and SPOT images, were used to locate and quantify the changes. Results show that from 1987 to 2007 the reclamation in Nansi Lake was serious. A large part of the lake had been replaced by land, the open water region only accounted for 51.3 percent. Farmland was distributed along the coast of lake accounting for 13.3 percent. Aquaculture ponds area was 37430 hm²，accounting for 29.7 percent. Comparing the three time period (1987-1991, 1991-1999 and 1999-2007), more changes in the cover areas occurred during the period 1991-1999 and 1999-2007 which is characterized by human interventions.

Abstract: The paper researches how to import the large amount of discrete data into 3DMAX and realizes high precision 3D terrain modeling. By analyzing and researching the data type and the feature of discrete data which can be accepted in 3DMAX, this author proposes a technical by importing data to ArcGIS, adding and modifying the characteristic points and lines, smoothing the data, exporting the 3D model in the use of the ArcGIS, and finally importing the result model into 3DMAX, and then generating the high precision 3D terrain model. In practice, the feasibility of this process is proved very well.

Abstract: Based on the current condition of Guangzhou subway network, the authors used GIS methods and extended the space syntax theory to analyze the accessibility of the subway network, and compared with actual passenger flow. The results show: 1)Space syntax is practicable to measure the accessibility of subway system; 2)Among all sections by division, the accessibility of Tiyuxilu-Chen Clan Academy is the highest, the accessibility of Yantang-Panyu Square is the second highest, while the accessibilities of Jiaokou–Xicun and Dongchong–Jinzhou are the lowest, the accessibility of Xilang -Chen Clan Academy is the second lowest; 3)The accessibility level of subway and actual passenger flow have a positive correlation, the higher the accessibility, the larger the passenger flow; 4)As a whole, line 1 has the highest accessibility and the largest passenger flow, followed closely by line 3. Their departure frequency and number of carriages should be properly increased to relieve passenger flow pressure. Line 4 has relatively low accessibility and less passenger flow, so it should appropriately decrease train frequency or extend departure interval to reduce operating cost at present. Certainly, space syntax inevitably has its limitations, but after proper extension, the space syntax method can be used to instruct traffic reconstructing and urban planning etc.

Abstract: The three-dimensional information of urban buildings is an important issue in urban monitoring, urban planning, urban management and various economic activities. In this paper we introduce a probabilistic approach of urban buildings’ height and location extraction on remote sensing image. According to the distance between the corner of building roof and its shadow on remote sensing image, buildings’ height can be extracted from single remote sensing image and buildings’ location also can be extracted from the classified image. Compared with the measured values, the absolute error of extracted urban buildings’ height and location is less than 1 m. The method is simple, fast and efficient, and is useful in the three-dimensional information extraction of urban buildings.

Abstract: A system model for web deployment of 3D terrain which mode is Browser/Server based on J2EE tri-tier system framework is given in the paper. Technology of Applet, JSP, Servlet, Java3D and BC4J has been integrated in the model. The main idea of this model as follows, using Java3d to develop the Applet that can interact with user, and the Applet embeds in web page of JSP. The Applet applies agent server, BC4J to communicate with server of Oracle database. The experiment shows that this model has some certain superiority.

Abstract: This paper process spectral data of the water based on normalization and Envelope elimination methods, by correlation analysis between land surface spectral data of single band or combining band and concentration of chlorophyll a and Suspended Solid to select band with max correlation coefficients, construct the best linear regressive models between spectral data and chlorophyll a and suspended solid. Firstly, the reflectance of the land surface of Hyperion images were obtained through geometric rectification and atmospheric modification adopted the 6S model, then the maps of spatial distributions of the concentration of chlorophyll a and suspended solid in the Nansi Lake were obtained using the best linear regressive model of chlorophyll a and the best linear regressive model of suspended solid. The results show that, data process of envelope elimination can remove the effect of the background spectral effectively and stand out the features of spectral absorption and reflection, and the combination of spectral R₇₀₀/R₅₆₀ and R₇₃₆/R₇₅₉ can be used to retrieved the concentration of chlorophyll a and suspended solid in the Nansi Lake.