Applied Mechanics and Materials Vol. 711

Abstract: Since twentieth Century 40's, some foreign enterprises in developed countries began to study and produce sweeper [1-2]. Research on China's sweeping car began in twentieth Century 60 years, but until the 80 time end when china had been reforming and opening that it began to rapidly develope [3-4].But the study of mouth has the same general trend at home and abroad. Due to the different design of suction mouth, circulation type pneumatic conveying systems in general can be divided into open pneumatic conveying system using pure suction type suction mouth [5] and the use of reverse blowing type suction mouth delivery system [6]. Now most of the sweeper adopts the latter, but if the back blowing type suction mouth design improperly ,it can not achieve the ideal effect of absorbing dust, and may lead to strong fugitive dust [7-9].Today although road sweeper have been studied for decades at home and aboard, but these studies mainly is through the enterprise using engineering practice means to complete ,there are two situations occurring as follows: a number of technical on research and development need to rely on our own to explore; The engineering practice have greater demand for human, material and financial resources, and it is difficult to achieve better expected. In order to solve the problems of the above two points, according to the fluid mechanics analysis, this paper mainly research and analyze the sweeper suction mouth's flow field pickup role of entrainment process for particulate contamination by negative pressure suction, which can provide a foundation for the research and optimization of sweeper pneumatic conveying system.

Abstract: Efficient ventilation and sound air current are significant to improve indoor air quality (IAQ) and control the contamination concentration. Healthy and comfort air conditioning will provide a strong guarantee for high-performance work. While limited by lots of conditions, the airflow distribution in room is very difficult to be revealed, so numerical simulation and analysis for airflow organization become more and more important during the design stage of ventilation and air conditioning system. In the paper a ship accommodation is taken as a model to do simulation analysis on the effect of different airflow organizations. On the basis of computational fluid dynamic (CFD) theory and methodology, the temperature fields, velocity fields and air age fields under different airflow organizations are gotten by means of Airpak3.1. All these search works will be helpful for the further design and optimization for the ventilation and air conditioning system of the ship accommodation.

Abstract: The basic principle of sequential quadratic programming method and the concrete implementation steps in MATLAB are expounded. Sequential quadratic programming method is used for the cabin structure optimization. In the optimization, the minimal sizes of components stipulated by the rules are used as size constraints, the frequencies required by the rules are used as performance constraints and the minimum lightness of the ship are used as objective. Finite element analysis of the ship structure optimized is done and the results obtained show that both the maximum equivalent stress and the maximum shear stress meet the requirements and first three order frequencies of the cabin structure are also far away from the working frequency of propeller and host. The optimization reduces the weight of the cabin under the condition of meet the static characteristic and dynamic characteristic.

Abstract: The selection, fitting and evaluation methods of response surface functions are expounded. The parameter sensitivity analysis of the cabin is carried out. The response surface functions of the stress and the vibration frequencies are constructed through the Box-Behnken experimental design method. Fitting inspection on the response surface functions is done with correlation coefficient, correction coefficient, etc. The results show that the response surface models are very similar to the real models. Four design variables are extracted randomly as the test sample of each response surface function. The data gotten by the response surface function are compared with the data gotten by the finite element analysis. The results show that the response surface models are with high accuracy and can reflect the real test values well. These response surface models can be used for further optimization design. They are helpful in reducing the ship mass without exceeding the allowable stress and resonance.

Abstract: In order to test the performance of a cannonball, various types of media are used in a test site. The best media should have good stability, effectiveness, economic feasibility, etc. Among them, sand is most widely used. Sand, which consists of many small grains, can be used effectively in a site. In this study, the penetration depth of a cannonball is analyzed for shear modulus using FEM. It is found that the penetration depth decreases with the shear modulus of sand. For management of a test side, the shear modulus of sand is an important factor.

Abstract: Double-column vehicle lift is a lifting equipment commonly used in auto repair and maintenance units, which is widely applied to the repair and maintenance of small vehicles such as cars. The design is a double-column vehicle lift driven by hydraulic. It mainly consists of lifting device, synchronous drive, column and bracket arm. The hydraulic circuit of hydraulic lifting device is designed. Currently, the articles concerning solidworks in the design of hydraulic drive lift only focus on unilateral appliance. When it comes to the design of the system, most of them concentrate on part modeling, virtual assembly, finite element analysis of parts ,etc, or a partial function of certain lifting machine. Seldom of them make a systematic research concerning motion stimulation. This paper, however, makes a three-dimensional virtual modeling for the lifting machine by the use of solidworks. In addition, it makes a structure verification of lift with assembly and motion simulation.

Abstract: According to the thermal experiment data and correction curve of heat supply units, the mathematical analysis formula of thermodynamic characteristic has been given accurately in this paper. Moreover, the mathematical model with objective function and the constraint condition for parallel operation of several heat supply units has been built up. By using simplex method and improved SCDD(Synthesized Constrained Dual Descent) method on the basis of the mathematical model, optimal distribution of heat and power load between heat supply units has been realized, and result indicates that this model is reliable and may achieve the goal of energy conservation.

Abstract: Accurate and timely recognizing whether gas wells get effusion is one of the important guarantee to ensure the normal production of water-cut gas well. It often gets errors when using current normal recognizing methods of the critical carrying fluid flow model to predict and recognize the actual flow situation in these wellbores, which already have effusion or have been drained effusion by taking measures. This paper is based on the coordinating relation between the energy of gas well itself and the energy required for draining effusion out, establishing a new method to recognize gas well effusion, and establishing a relatively complete system of gas well effusion identification. Combined with field production data, this method can be more accurately used to recognize gas effusion and real-time trace, and it can avoid the above problems. Combined with the instance of gas well for real-time effusion diagnosis, the predicted result is very good agreement with actual situation. This new method has important guiding significance for the normal production of water producing gas wells and the implementation of related gas recovery with water draining.

Abstract: An antibacterial agent (ZPU) was prepared by surface modification of nanoZnO with aliphatic aqueous polyurethane (WPU) and polyacrylates sodium of lower molecular weight (LPAA). Then two kinds of cotton fabrics were dipped in ZPU and finally finished by paking-baking process. ZPU and the finished cotton fabrics were characterized by SEM, TEM and DLS. The antimicrobial properties of the cotton fabrics were investigated. The results indicated that ZnO retained nanosize with little aggregation on the fabric surface. The finished cotton fabrics showed obviously antibacterial activity against S. aureus and E. coli with the 24 h antibacterial rate of 99%.

Abstract: Mechanical behavior and failure mode of jointed rock is one of the significant researches in rock mechanics field. In this work, combined with similar material testing and discrete element numerical method(PFC) to investigate the mechanical behavior and failure mode of the rock-like materials with multi-fissures. The numerical analyses agree well with physical experimentation. It is found that, fissures will weaken the strength of the rock-like material, and when the angle of the fissures is about 25°, the strength of the material reaches a minimum value. The weakening effect of fissure on specimen strength would decrease gradually along with the increase of fissure angle. Compared with the effects of fissure angle, the influence of cracks number to the strength is relatively small. The fissure inclination angle was the main factor of the failure modes. With the different fissure inclination angles, the crack tip of Micro-cracks presents different developmental pattern. However, the influence of fissure distribution density on the failure mode mainly reflects at the fracture penetration mode.