Applied Mechanics and Materials Vols. 121-126

Abstract: Addition of supplementary cementitious materials (SCM) has been contradictorily reported to be beneficial or detrimental to the flowability of concrete and no general conclusion can be drawn up to now. In order to comprehensively disclose the effects of SCM on the flowability, an experimental study had been carried out to measure the flowability of a total of 100 cement paste samples with different condensed silica fume (CSF) and superfine cement (SFC) contents at a wide range of water/cementitious materials (W/CM) ratios. The results showed that the addition of CSF would decrease the flowability at a relatively high W/CM ratio but increase the flowability at a low W/CM ratio, while the addition of SFC could generally improve the flowability of cement paste. Joint addition of SFC and CSF would not exert any definite effect on flowability at a relatively high W/CM ratio but could improve the flowability at a low W/CM ratio. In-depth analysis showed that these results could be well explained by the theory of water film thickness.

Abstract: Grinding process is regarded as the most effective way to generate the tooth profile of spur shaper cutter. However, for the purpose of generating a tip chamfer of gear, the semi-topping is always required on the tooth surface of shaper cutter, which is difficult to process by grinding wheel. This paper proposes a method to compute the profile of grinding wheel which is used to process the spur shaper cutter with a semi–topping. Firstly, translate the points on the surface of shaper cutter into auxiliary rack; Secondly, building the relationship between the coordinate system of grinding wheel and coordinate system of auxiliary rack; Lastly, the points on the surface of auxiliary rack are translated into the coordinate system of grinding wheel based on the relative motion between the grinding wheel and shaper cutter.

Abstract: As a type of solid state switch, MR (magnetoresistive) sensor detects the air cylinder piston’s position in pneumatic control system. The construction and working principle of the air cylinder with MR sensor are introduced. Using 2-D magnetic field finite element analysis (FEA) method, the magnetic field distribution of air cylinder with piston motion is analyzed. Simulation results are given. The magnetic flux density characteristics are compared between piston wear or not.

Abstract: With the requirements for reducing emissions and improving fuel economy, it has been recognized that the electric, hybrid electric powered drive train technologies are the most promising solution to the problem of land transportation in the future. In this paper, the parameters of series hybrid electric vehicle (SHEV), including engine-motor, battery and transmission, are calculated and matched. Advisor software is chosen as the simulation platform, and the major four parameters are optimized in orthogonal method. The results show that the optimal method and the parameters can improve the fuel economy greatly.

Abstract: As an important engineering work, maintainability design, analysis, evaluation and other activities runs through the entire weapon equipment development process. To solve the current maintenance puzzle in the beginning, and let the maintenance in time, economic and effective, this paper build up the weapon equipment maintain-ability lifecycle models from function view, information view and process view oriented on the concurrent engineering (CE). Accordingly, put the maintainability design, analysis and evaluation works in to practice throughout the weapon equipment system analysis, design, manufacture, test, evaluation and other engineering activities in the earlier phase of weapon equipment system demonstration, thus can make the equipment have the best maintainability character by the roots.

Abstract: White LEDs can show different correlated color temperature (abbreviated as CCT) by adjusting the luminous spectrum peak distribution and relative strength. Recent research results indicate that spectral luminous efficiency function of mesopic vision Vmes(λ) and equivalent brightness are associated with luminous spectra of light sources. A series of white LEDs with different CCT are tested and calculated, it shows white LED with higher CCT has higher mesopic vision equivalent brightness, although the brightness are identical when the tester corrected by traditional photopic vision spectral luminous efficiency V(λ). From the equivalent brightness curve fitting, the curve can be described as a polynomial function, for it excellent correlation, the more value of equivalent brightness could be calculated without complex derivation.

Abstract: The paper deals with the problem of estimating the S-N curve for the cement based composites under fatigue loading. Selected approximation curves for mechanical-fracture parameter values derived from specific fracture energy in time are used to determine the most accurate fatigue parameter values corresponding to the age of specimens when dynamic tests were performed. For standard description of S-N curve the power dependence and Weibull model developed by Castillo et al. are used to discuss the problem under study and the suitability of using models as an input data for finite element modeling

Abstract: The cementing quality is directly related to the normal operation of the gas well, therefore, the evaluation of cementing quality is key to the correctly use the gas well as well as to take measures to protect the gas well. In this paper, four first wave amplitudes at the same depth point when using the borehole compensated sonic logger with double transceiver technique to carry out the acoustic amplitude log operation are served as the discriminant factors to evaluate the cementing quality. Taking the engineering actual measured data as the learning samples and using the particle swarm optimization to optimize the parameters of support vector machine, this paper established the intelligent evaluation model for cementing quality based on genetic algorithm (GA) and support vector machine (SVM). The model employs the excellent characteristic of SVM which has high speed of solving and could describe nonlinear relation as well as the characteristic of GA which has global optimization. Through test of engineering samples, the research result showed that this model has fast astringency and high precision, providing a new method and approach for the fast and accurate evaluation of the well cementing quality.

Abstract: This paper is about the KF301/WS2 modified lubricating wear-resisting coating which is prepared by supersonic plasma spraying, laser remelting and surface texturing technology, tribological characteristic of KF301/WS2 lubricating wear-resisting coating of four different (round pit, diamond, parallel and intermittence) tracks and part laser remelting is studied under room temperature. Research shows: textures of different tracks have a certain influence on friction factor of coating’s surface and abrasion loss. Friction coefficient of mouldling surface of broken texture is about 0.012 in the initial stages, while friction coefficient of round pit texture is about 0.0085. Round pit, diamond and parallel microtopography make friction state enter stabilization quickly, effectively restraining the wave of abrasion loss. When wear time reaches to 1 hour, abrasion loss of broken texture is 0.03mg, while abrasion loss of round pit texture is about 0.015mg. Tribological properties, from high to low, in turn, are round pits, diamond, parallel and broken texture.

Abstract: This paper presents an experimental study on the energy saving effect of building envelope in winter in Chongqing city. The basic cubicle was adopted for comparison. Experiments show that when energy saving measurements are applied in the external walls and windows, energy saving cubicle has an average energy efficiency rate of 32.68%, 7.68% over the target value of the standard. The indoor temperature of the energy saving cubicle is higher than the basic one’s. The internal surface temperature and the temperature difference between the exterior and interior of the insulation wall of the energy saving cubicle are both higher than that of the basic cubicle, the mean value is 1.28°C and 1.90°C respectively. And the temperature difference of the insulation glass is higher than that of the single glass, with a maximum value of 6.32°C. Daily simulation of the two cubicles is addressed by VisualDOE-4.0, the mean error between simulation and experiment is 16.16%, illustrating the effectivity and the accurateness of the VisualDOE-4.0.