Applied Mechanics and Materials Vols. 638-640

Abstract: The contribution deals with leakage of natural gas from domestic low-pressure piping. Spreading of the leaked natural gas in the confined space is deals with and the areas are defined where local hazardous concentrations are formed. Mathematical CFD models provide broad overview of spreading of natural gas, in dependence on the elapsed time from the start of leakage. The contribution should improve the understanding of spreading and distribution of mixture of gaseous fuels in confined spaces, and thus leads to significant reduction of the risk of occurrence of fire or explosion or to prevention of these hazards.

Abstract: In this paper, we shall first briefly introduce the hydraulic junction of three-sources branched heat-supply network and the related optimization method. It's difficult to guarantee that the system runs in optimal state and it increases energy consumption in the system. In view of this situation this paper proposes a method to find the optimal positions of hydraulic intersections based on analyzing a real heating system with three heat sources in Jining. The optimization objective is to minimize the electric power consumption of circulating water pumps in district heating system. Finally, optimization programs are designed and the optimized results verify the feasibility and validity of the method compared with conventional experience values.

Abstract: In this paper, we shall discuss the calculate method of heat loss of central heating pipes.the calculation formulas available are too complicated and inconvenienced to analysis the dynamic thermal conditions of heating pipeline. Therefore, this paper presents one order polynomial with least-squares solution, and then establishes linear equations of heating pipeline heat loss that the hot water temperature as a variable alone. It is based on the comparision and analysis of buried hot water heating pipeline heat loss formula. This method will simplify not only the calculation, but also the model of calculation analysis for different diameter, different insulation materials. The result is that the deviation of the formula is caused mainly by the thermal resistance. The relative errors of simplified formula and the selection formulas are less than 3%, which can meet the requirements for engineering applications.

Abstract: All-year thermal dynamic load simulating and energy consumption analysis for new energy-saving building is very important in building environment. According to thermal instantaneous response factors method, the paper develop a software to calculate air conditioning cooling load temperature and the dynamic thermal basic data that involve thermal response factors, periodic response factors, Z transfer function coefficient for new energy ­saving walls in building, which will provide the referable scientific foundation for all-year new thermal dynamic load simulation, energy consumption analysis, building environment systems control, carrying through farther research on thermal particularity and general particularity evaluation for new energy ­saving walls building. based on which, we will not only expediently design system of building energy, but also analyze building energy consumption and carry through scientific energy management. The study will provide the referable scientific foundation for carrying through farther research on thermal particularity and general particularity evaluation for new energy saving walls building.

Abstract: An indoor cooling pond heat dissipation test was conducted under specified climatic conditions. When cooling pond was in thermal equilibrium, different levels of error exist between dissipating heat flux calculated by four empirical formulae and receiving heat flux provided by heating system, and the formula used in the same area where it is developed got a quite good result. When a heat transfer coefficient formula is used not in the area where it is developed, and if the recalibrations of parameters contained in formulae are neglected, large errors will be expected.

Abstract: Determining exterior orientation elements of image is an important task in photogrammetry. Considering some shortcomings in various classical methods, a new algorithm based on angle-axis to represent rotation was presented. Based on the least square principle, the closed-form solution of angle-axis and coordinates of perspective centre were solved out first; then the rotation matrix and angular elements were derived. Lastly the six exterior orientation elements were obtained. Compared with the traditional space resection based on the classical collinearity equation (Euler angles) method, angle-axis representation method of space resection can be removed from a large number of cumbersome trigonometric functions, simple equations structure, easy to program implementation. Simulation data test described space resection solution based on angle-axis is fast, effective and stable.

Abstract: The design and Realization of the scenic spot electronic sand table system as the core of electronic sand table, such as remote sensing, and geographic information system, 3D simulation technology and other related concepts were introduced, the electronic sand table overall data structure and process analysis, discusses how to establish the electronic sand table based on ArcGIS software and realize its function, resulting inconvenience the tour guide teaching at the same time,upgrade the development level of tour industry.

Abstract: In this paper, combined with the first phase of wuhan rail transit line No. 4 line network management service center B building curtain wall engineering practical problems, Auto CAD auxiliary polar coordinate method is used to rapidly and accurately complete curved plane positioning pay-off, forming method, this method has been applied in several projects, produced good economic and social benefits.

Abstract: 3D terrestrial laser scanner (TLS) provides both 3D point coordinates and intensity data of scanned object surface. The intensity data can be used to discriminate different materials, since it partly represents the object reflection characteristic at the laser wavelength. In addition to laser reflectance properties of object, the intensity data is influenced by many other factors, such as instrument mechanism, environmental condition, distance and incidence angle. In this paper, the effects of distance and incidence angle are studied. Except for standard reflector, some building facades of various kind of material were used as experimental samples. Experimental survey find that the intensity is inversely proportional to distance and incidence angle, but their relations do not agree with the theoretical model. Several models were selected to describe the relations between intensity and distance, intensity and incidence angle. The suitability of each model was analyzed by its correlation coefficient.

Abstract: Based on measurement data acquired by GPS-RTK (Real Time Kinematic) technology, this paper established a three-dimensional traces model on digital terrain. Then Zhang and Einstein method and H-H method were chosen to estimate the mean trace length of discontinuities. The results using these two methods are both very close to the reference value. It shows the feasibility of these methods and the rules for setting digital windows in this case.