Abstract:The construction environment of shallow tunnel under asymmetrical pressure of the mountains in the southwest of China was analyzed from the viewpoint of geographical, topographical and geological. According to the denaturations of medium parameter and load as well as the complexity of the mechanical transmission mechanism of the lining structure, the model of stress and displacement double equivalent back analysis for getting the parameter of tunnel medium and the optimization algorithm was studied on the basis of the strength and deformation control principle of the lining structure stability, and the implementation procedures were straightened out. Then, the characteristics of the characterization parameter and unbalanced depicting index for the supporting structure of the shallow tunnel under asymmetrical pressure were refined. In the end, the mechanical response of the supporting system was studied in the finite element numerical method, and the bearing characteristics of the support structure for the shallow tunnel under asymmetrical pressure were summarized in order to provide guidance for similar engineering in design and construction control.

Abstract:Experimental research on the shear test behavior of different shear-span ratios and different stress modes was carried out through the experimental research on two general beams and four RC beams strengthened with steel fiber ferrocement mortar. The regulation for the change of the mode of failure, diagonal cracks, deflection and strain was analyzed in the experiment. According to the test results, the computational formula of the shear load capacity of RC beams strengthened with the steel fiber ferrocement mortar was established. The calculation results fit well with the experimental results, which provides a theoretical reference for actual engineering designs.

Abstract:In order to investigate the mechanical behavior of the hybrid system for the glass roof structure of new Guangzhou Railway Station, the prestress design of the lower cable-strut system was discussed. Then, the effect of the flexible members on the static behavior was studied. The linear eigenvalue buckling analysis and nonlinear buckling analysis on this system were carried out. At last, the influence of the area of upper steel beams, the area and prestress value of the upper track bars and lower cables on the vertical stiffness was investigated. The results have shown that the upper track bar and lower cable increase the structural stiffness. The whole stability of the hybrid system of this project can meet the demand, but the end of the structure is the weakest area. The structural vertical stiffness increases with the increase of the area of the upper beams. Moreover, the increasing area and prestress value of the upper track bar slightly increase the vertical stiffness. The influence of the area of the lower cables on the structural stiffness is significant, but the stiffness is not appreciably affected by the prestress of lower cables.

Abstract:To analyze the gas flow in an axis-in cyclone separator, a two-stage turbulence model based on the RNG κ-ε model combined with the Reynolds stress model was developed. The RNG κ-ε model was first used for the gas-phase of five cases of the cyclone. When the gas flow field was stable, the particle phase was added to the gas-phase and the Reynolds stress model was used for the gas-phase. A stochastic trajectory model was employed for the particle phase on the basis of the gas flow field, and the resistance and efficiency of the cyclone were calculated. Finally, a typical case was measured. The results agree reasonably well with the numerical results. Therefore, the simulation method based on the two-stage turbulence model is reliable for the study of the gas flow in axis-in cyclone separators.

Abstract:This paper proposed an optimization control method for fresh air rate based on the objective function of energy consumption. By establishing the module of optimization control, a simulation analysis was carried out for an office building of Hong Kong on TRNSYS platform. The simulation result has indicated that, compared with minimum fresh air requirement control, the optimization control has not only saved the energy consumption of fresh air fan, but also reduced the energy consumption of refrigerators, chilled water pumps and cooling water pumps. The air-conditioning system with the optimization control can save 2.73×105 kWh in a year and the energy-saving rate reaches 17.1%. Its energy-saving effectiveness is remarkable. Especially in most time from November to March, the optimization control not only reduces the energy consumption of air-conditioning system, but also greatly improves indoor air quality.

Abstract:CFD analysis was carried out on the in-cylinder and water jacket with AVL-Fire. In order to achieve the conjugate heat transfer, the convection thermal boundary conditions were coupled to the calculation process of the solid heat conduction with FE technology. The calculation of the cylinder head stress under the mechanical and thermal load was done. Finally, the mechanical-thermal fatigue integrating the material properties corrected by temperature, and the access to the safe factor, were analyzed. The results have shown that, in terms of the fatigue of cylinder head, the contribution of thermal load is noticeably greater than the mechanical load. The results have also shown that the cylinder head design meets its work demand.

Abstract:Based on the potential flow theory, a two-dimension mathematical model of oscillating water column (OWC) wave energy device was obtained. The fully nonlinear wave was simulated in the desigularized boundary integral equation method (DBIEM). The anti-reflection was achieved by adjusting the amplitude and phase of the oscillating air pressure in the OWC's chamber. The relationship of the wave energy absorption efficiency with the amplitude and phase of the oscillating air pressure in the OWC's chamber was investigated. Numerical results have shown that the wave energy absorption efficiency of OWC at anti-reflection is much higher than that of the traditional OWC. Under the condition of anti-reflection, the amplitudes of the oscillating air pressure in the chamber and the flow through the turbine are much higher, and the phase differences between the two are observed, which differ from the traditional OWC. A novel design idea of the OWC wave energy device was also presented.

Abstract:A 2-D electromagnetic simulation model of the large gap magnetic drive system driven by traveling wave magnetic field was established, and the magnetic moment for the four pole-states when the angular displacement of the permanent magnet ranged from 0°to 360° was simulated with ANSYS software. In order to get the largest driving torque of the system, the concept of the best phase angle for the pole-state of the electromagnets was presented. The approximate formula for the best phase angle was drawn by analyzing the influence of the coupling distance and electromagnet-pole distance on the best phase angle of the system. The largest load torque of the axial-flow blood pump for different phase angles was calculated and compared by using load torque model through experiment. The results have shown that the best phase angles obtained through simulation can get the largest driving torque.

Abstract:A modified Mumford-Shah model with nonlinear statistical shape prior was proposed to segment the optic nerve head in fundus images of poor quality, very low contrast, obscurity due to blood vessels, and distinct inter-differences of individuals. Firstly, the narrow band level set of shape prior was mapped into its kernel space by a nonlinear kernel function. Then, principal component analysis (PCA) was performed in the kernel space so as to acquire its base vectors, and statistical shape prior was integrated into a Mumford-Shah model. The segmentation results of the color optic nerve head images of patients in different stages of glaucoma have showed that the proposed model is effective and practicable.

Abstract:Axial flux machines can compete with traditional radial flux machines in terms of torque and power density if the number of pole-pairs is sufficiently high and the ratio of axial length to outer diameter is low. However, it is difficult to manufacture the armature core of the axial flux machine. So this paper proposed a new method. The stator of the machine was realized by using soft magnet compound (SMC) to form a teeth, which was combined with a strip punched laminated core and concentrated winding. Then the electromagnetic design of the machine was performed, and the magnetic field was simulated in the Ansoft Infinite Element Analysis method. Design results and simulation results have indicated that the suitable choice of the main dimensions of the machine and the ratio of the number of pole to slot can achieve sinusoidal emf waveform and small cogging torque.

Abstract:C-SiC-B4C composites were prepared by using a mixture of phenolic resin binder, SiC,B4C, flake graphite, green coke and calcined pitch coke as the raw materials for uniaxial compression. The influence of the raw materials on the performance and microstructure of C-SiC-B4C composites was investigated. The result has shown that the C-SiC-B4C composites prepared with raw materials of green coke possess excellent compressive strength, while those prepared with raw materials of flake graphite present the lowest resistivity and the best oxidation resistance.

Abstract:TiB2-SiC composite powders were synthesized by carbothermal reduction using silica sol, carbon black, TiO2 and B4C as the raw materials. The effects of reaction temperature and titanium oxide content on the phase composition and morphology of TiB2-SiC composite powders were investigated. Thermodynamic analysis and calculation were performed systematically during the reaction, and the growth mechanism of TiB2-SiC composite powders was discussed. The results have shown that the suitable condition for synthesizing TiB2-SiC composite powders is at 1 600 ℃ for 1h. In the reaction process, TiB2 is formed before SiC, and the formation of TiB2 alters the growth mode of SiC. When TiB2 content is about 10%, the formation of SiC is controlled by the vapor-solid reaction to the combination of vapor-solid and vapor-vapor reaction. The composite powders are mainly composed of a small amount of round-like particles, short rod-like particles and a lot of whiskers. With the increase of TiB2 content in the composite powders, the growth of SiC whiskers is inhibited. When TiB2 content is more than 20%, the number of whiskers in the composite powders reduces, and the number of round-like, plate-shaped and short rod-like particles increases noticeably, which results in a variety of the morphology. The growth of SiC is still controlled by the combination of vapor-solid and vapor-vapor reaction.

Abstract:In order to investigate the siltation mechanism of intercepting well with pressure, CFD was applied for numerical simulation, which was validated with field measurement data of sonar. On the basis of critical BSS model based on DPM, the probability selection method of GA was applied from a new point of view to put forward "probability sedimentation" model of particle. This model worked effectively on the simulation of silt surface and relatively siltation depth, which was validated with field measurement data of sonar. The results have shown that the silt surface of x-direction is a slope and there is a bulge with a location insensitive to flow. The silt surface of y-direction is concave and the middle surface swells while both sides tend to be flat because of scouring. The field measurement of sonar has shown that the silt depth in intercepting well is strongly relative to dry weather flow while the siltation condition of main intercepting pipe is relative to intercepting well.

Abstract:Poyang Lake wetland, one of the world's six major wetlands, was taken as the research object. The theories and technologies of geographic information system, remote sensing, global positioning system, spatial database, three-dimensional virtual simulation and hydrodynamic theories were adopted to construct the fundamental geographic information system for Poyang Lake wetland, which integrates the expert knowledge, model and decision making functions. To a certain extent, this system solved the contradictions in wetland economic development, in which different sectors (e.g. environment, water conservation and land planning) are closely related, but are at the same time isolated from each other. And to some extent, this system realized systems integration development, three-dimensional modeling and simulation for hydraulic engineering, and the dynamic simulation and forecasting of flooding based on 3D WebGIS.

Abstract:To improve the spectral efficiency and user experience of terminals at cell edge of LTE-Advanced systems, two improved single frequency network (SFN) precoding schemes were proposed for coordinated multi-point (CoMP) transmission systems based on the existing methods, which can solve the problem of uncertainty when the channels are merged in traditional SFN precoding scheme. The first improved scheme adds a phase parameter to the transmitted end, which is determined by maximizing the channel gain after mergence. The second improved scheme takes a swapping function at some transmission points when the transmitted data is mapped to the antenna ports, and the swapping rule is also determined by maximizing the channel gain. Simulation results have shown that the two proposed schemes can improve the spectral efficiency of users at cell edge in both correlated and uncorrelated channel, and both low and high rank channel.

Abstract:This paper focused on how to quickly construct the topological relationship of cadastral data. Based on the space topological information of the cadastral data, a new algorithm of auto-constructing block polygon was given. This algorithm only requires the characteristic information of the graphic in auto-constructing block polygon, so it avoids calculating interior angle, comparing interior angle and coordinates, and considering some special cases. The example and its algorithm analysis have shown that the new algorithm dramatically reduces polygon repetitive search and improves the efficiency of polygon search.