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In the application background of virtual teaching system, the author analyzes and designs the collision detection algorithm of parallel space dividing in view of the requirements of collision detection process. Through the experiment, the author compares the two kinds of serial and parallel space division method on the operation efficiency of comparison, and adopts parallel space partitioning algorithm to improve the efficiency of collision detection as well.

TiO2/NCCN nanocomposites have been prepared by sol-gel and hydrothermal methods. Firstly, the NCCN was prepared by electrospinning technology, then the amorphous TiO2films were coated on the surface of the NCCN by a sol-gel method, and TiO2(anatase structure) nanoparticles could be fixed on the surface of NCCN by a hydrothermal method to get higher photocatalysis efficiency. The photocatalytic activities indicate that the TiO2/NCCN nanocomposites exhibited a good photocatalytic activity for photodegradation of methylthionine chloride (MO) solution under UV light irradiation, leading to an important application in photodegradation of organic pollutant.

It is first extended the log4j and then applied the log file distribution function of log4j in E-Commerce service system in this paper. In this way, it can avoid all log information are centralized interspersed in a single log file, effectively disperse the log information of different concerns, easy to monitor and analyze E-Commerce service system operation status. Key words: Log4j, dynamic log file, extension, e-commerce services

A high performance and high voltage half-bridge novel IGBT driver circuit is described in this paper. The module integrates dual insulated driving and special protection circuits. It has high push-pull driving capability, bootstrap power supply technology and is easy for inverter miniature design. The paper also introduces the application in portable diesel engine generator and discusses some attention items in practical application. Experimental results show that this driving module has better performance and can reliably drive and protect IGBT.

This paper presents the backtracking search optimization algorithm with low-discrepancy sequences to solve mechanical design optimization problems involving problem-specific constraints and many different variables. Similar to other evolutionary algorithms, backtracking search optimization algorithm is sensitive to the initial population. Generally speaking, since there is no information about the optimization problem, the initial population should be created uniformly. The low-discrepancy sequences are employed to increase the uniformity of the initial population. The benchmark problems widely used in the literature of mechanical design optimization are used to evaluate the performance of the presented algorithm. Results show that the proposed algorithm is effective and efficient for solving the mechanical design optimization problems considered.

The Fault detection and diagnosis for sensors are important for the performance of the complex control system seriously. The kernel principal component analysis (KPCA) effectively captures the nonlinear relationship of the process variables, which computes principal component in high-dimensional feature space by means of integral operators and nonlinear kernel functions. The KPCA method is used in diagnosing for four common sensor faults. At first its fault is detected by Q statistic; secondly its fault is identified by T2 contribution percent change. The simulation and the practical result show the KPCA method has good performance on complex control system in sensor fault detection and diagnosis.

Light steel houses are widely applied to low-rise industrial buildings for lightweight, easy industrialization and fast construction. But under the condition of strong wind, there often occurs wind-induced damages to light steel houses because they are sensitive to wind loads, causing huge economic losses. This paper offers a wind-resistant design for a steel structure warehouse which may suffer from force-14 super typhoon with maximum wind speed of 150 km/h. The main factors affecting the wind-resistant capacity of steel structure plants as well as the attacking characteristics and failure mechanism of typhoon on low-rise buildings are fully analyzed. Opinions on the design of low-rise steel structure warehouses against typhoon have been proposed by discussing different wind directions. Considering conceptual design, we also provide some concrete measures of wind-resistance for low-rise buildings in coast areas.

In order to understand the overall mechanical characteristics of a steel-concrete composite box girder bridge, static and dynamic tests were carried out. According to the results of tests and calculations, its bearing capacity and working performance were evaluated. The results show that the stress and deformation at control cross-section of the bridge meet design requirements under the static load, the vibration frequency and impact coefficient consistent with the theoretical calculation results under the dynamic load.

The integrated half-bridge IGBT driver need compact, high efficiency and high power density isolated DC-DC power supply, a set of two magnetic cores share a high-frequency full-bridge switches are designed. A simple circuit generates four channel drive signals, without isolation, to achieve compact on-board power supply and the best combination with the integrated half-bridge IGBT driver. The key signals are simulated, and experimental results show that the power supply is simple, reliable.

This paper based on the ideology of cloud computing, using the cloud platform of Google App Engine and Web Services technology, utilizing the eclipse, Google Plugin for Eclipse and Java Web, building a sharing platform for university network teaching resources. The design and implementation of the system reduce the capital investment and the burden of system development and maintenance costs, and will bring a great convenience to teachers "teaching" and students "learning. Practice shows that the cloud platform of teaching resources has high stability and scalability than traditional services technology, and can provide new ideas for the system design, so online teaching resource sharing cloud model can be achieved.

the control strategy has a direct impact on the performance of active power filter. Creating system model in the simulation software to research and analyze. Results show that the hysteresis comparison control method can track the harmonic current accurately, and control inverter circuit generate compensation current quickly and accurately. And doing spectrum analysis for the power grid currents before, the spectrum figures show that the power grid current harmonics has been suppressed greatly, and the compensation effect is very significant.

In this paper, two kinds of micro-mechanical models are utilized to predict the effective Young's modulus for hybrid composites including fiber-like, spherical and needle inclusions in an isotropic matrix. The two models of Multi-Phase Mori-Tanaka Model (MP model) and Multi-Step Mori-Tanaka Model (MS model) are proposed by the authors in a series of interrelated research. The results show that the shape and the Young’s modulus of inclusion, aspect ratio of fiber-like inclusion are the controlling factors to influence the Young's modulus, and MP model is more rational to predict the effective Young’s modulus of hybrid composites reinforced with multi-shape inclusions.

Based on the group explicit strategies, a new alternating group explicit algorithm for solving 2D diffusion equation was presented. The four new difference schemes which were constructed to implement the algorithm in parallel, can be converted to explicit computation. The stability and truncation error analyses were provided. Finally, numerical experiment was performed to examine that the the presented algorithm is efficient and accurate.

The thermal effect experiments were carried out of a direct air-cooled system in the low speed wind tunnel. The influence of effect factors on recirculation is also discussion, after that the relationship between the thermal flows field structure and recirculation ratio under the cooling tower is analyzed. At last, the engineering measures to reduce or avoid recirculation are proposed. For certain conditions the experimental measurement shows close agreement with numerical values.

By using the computational fluid dynamics code, FLUENT, Numerically simulation is investigated for Youngshou power plant. Under the constant ambient temperature, the effects of different wind speed and wind direction on the thermal flow field are qualitatively considered. It was found that when considering about the existing and normally operating power plants, the thermal flow field is more sensitive to wind direction and wind speed. Based on the above results, three improved measures such as: increasing the wind-wall height and accelerating the rotational speed of the fans near the edge of the ACC platform and lengthen or widen the platform are developed to effectively improving the thermal flow field, and enhanced the heat dispersal of ACC.

Multi-step Mori-Tanaka method (MMT) is applied to the estimation of the effective mechanical properties for composites with three-phase randomly distributed aggregates in this paper. The Multi-phase Homogenization Theory (MHT) which is based on mathematical homogenization method and is employed to verify the results of MMT method. Results show that MMT method is reasonable and practicable to predict the effective mechanical properties of composites with several phases, and the Young’s moduli and Poisson’s ratios of each phase may have some effects on the effective mechanical properties of multi-phase composites.

Due to the complexity of underground engineering, study on creep characteristics of surrounding rock mainly adopts laboratory simulation experiment. Recently, the similar materials are used to do the experiment both at home and abroad, yet it can't reflect the original nature and others of rock fissure in original rock mass. Through the field collection of undisturbed sample of Tertiary mudstone, the conclusions are made by laboratory model test on surrounding rock of underground tunnel and creep process regularity and failure mechanism in the surrounding rock in this paper as follows: there are three obvious stages of creep under certain stress levels, which is measured on the surface of surrounding rock mass in argillaceous soft rock tunnel--decay creep ,steady creep and accelerated creep. The surrounding rock will produce the accelerated creep damage when the stress level is over a threshold value. Creep damage of surrounding rock mainly includes the forms of roof sinking, floor working up, and forming a macro- fracture surfaces etc. Test results showed that the undisturbed surrounding rock fracture would be dissimilar to the homogeneous surrounding rock without fracture in damage model, and original fissure have a larger effect on creep damage of surrounding rock.

In the past, when used the foundation coefficient to calculate the internal force of anti-slide pile, power series method is usually adopted. The deformation compatibility conditions and continuity conditions of sliding surface between non-anchoring section and anchoring section are exploited to determine the final result, causing the lengthy solution process and that there is no guarantee for the calculation accuracy. This paper uses the foundation coefficient method in the calculation of internal force of anti-slide pile and employs the “m-k” method with a more complicated up-down foundation structure to get the finite difference equation to determine the new-type deeply buried anti-slide pile displacement and internal force. Then the calculation on the internal force and displacement of the whole pile can be realized easily through the procedure method. Finally, this paper makes a contrastive analysis on the result of the finite difference method and finite element calculation through the case study. As long as the equal differential step length is small enough, the calculation accuracy can meet the demand of engineer design and the program graph processing result can optimize the design of anti-slide pile.

Based on a series tests, the properties of proto-machine-made sand of gravel such as grain feature, fineness modulus, grading, density, void ratio and MB value as well as the fineness distribution of stone powder were studied, the influences of content of stone powder on these properties of sand and strength of cement mortar were investigated. The results are introduced in the paper, some of them contribute to explain the special properties of concrete mixed with proto- machine-made sand.

This paper briefly introduced the design and operation features of capillary air conditioning system, put forward multi-objective optimization problem in hydraulic calculation process, using genetic algorithm to solve multi-objective optimization problem and established a capillary air-conditioning system hydraulic calculation model. The problems of hydraulic calculation were transformed into the problems of multi-objective optimization Pareto optimal solution using genetic algorithm (GA). And GA was applied to illustrate corresponding to specific model. The optimal specific frictional resistance under the different flow conditions was described here.