Applied Mechanics and Materials Vols. 34-35

Abstract: In this paper, we study how the geometry of helical intake port of diesel engine influent air flowing conditions to reduce the complexity and difficulty of getting air flowing conditions by experiments. In numerical modeling, we import model of intake port into ANSYS software and do mesh processing on intake port in sections. We then analyze air flow based on working conditions, including difference of pressure between intake and exhaust port and lift-range. We deal with data by post-processing module in ANSYS and obtain velocity distribution and turbulence energy distribution of intake and exhaust port. Finally, we can predict the performance of intake port and find optimizations theoretically.

Abstract: Cuprous oxide films are successfully electrodeposited through the reduction of cupric ions in alkaline and acid electrolytes. The effect of electrodeposition parameters on the optical band gaps of Cu2O films is investigated using UV-vis spectroscopy. It is found that the optical transmittances and the band gaps of the Cu2O thin films are strongly influenced by the electrodeposition bath, the temperature, the current density, and the pH value. The band gaps are varied from 1.80 eV to 2.43 eV with different electrodeposition parameters.

Abstract: Standard TCP has lots of problems; for example, the network bandwidth can not give its full play in certain application conditions such as high speed or long distance. High Speed TCP (HSTCP) can solve these problems, but it has serious problems in the fairness of different RTT. Based on the analysis of HSTCP fairness, an algorithm of adding fair factors to improve fairness of HSTCP has been put forward after fairness simulation test by NS2. NS2 simulation experiments prove that this algorithm has greatly reduced the unfairness because of the different RTT.

Abstract: Fretting wear behavior of 40CrNiMoA steel was studied on a SRVⅣoscillating friction and wear tester. The results indicate that the fretting wear volume increase with test frequency, load and amplitude increasing. Meanwhile, the fretting wear mechanism is directly related to test frequency, load and amplitude. When they are small, the main fretting wear mechanism is abrasive wear, with these test parameters increasing, the main fretting wear mechanism turns to a combination of abrasive wear and adhesion wear. Based on the experimental results, the anti-fretting wear measures of steel worm gear pairs used in mechanical tracked regulator of tracked vehicle are discussed.

Abstract: Green design is a key technology of green manufacturing. Compared with traditional design, green design requires taking into account the environment factors and pollution prevention measures in the product design during the designing phase. The basis to build an evaluation system of green design based on life cycle is a combination and integration of data and knowledge of different phases in product life cycle. Hence, this paper builts a hierarchy structure model of green design under influence of many factors according to the frame of ISO 14000, determines the weight of each factor based on experts’ opinion, and makes a systematic evaluation on the performance of green design based on fuzzy hierarchy evaluation principle.

Abstract: This paper investigates the compressive strength and splitting tensile strength of ultra high strength concrete containing steel fiber. The steel fibers were added at the volume fractions of 0%, 0.5%, 0.75%, 1.0% and 1.5%. The compressive strength of the steel fiber reinforced ultra high strength concrete (SFRC) reached a maximum at 0.75% volume fraction, being a 15.5% improvement over the UHSC. The splitting tensile strength of the SFRC improved with increasing the volume fraction, achieving 91.9% improvements at 1.5% volume fraction. Strength models were established to predict the compressive and splitting tensile strengths of the SFRC. The models give predictions matching the measurements. Conclusions can be drawn that the marked brittleness with low tensile strength and strain capacities of ultra high strength concrete (UHSC) can be overcome by the addition of steel fibers.

Abstract: This paper mainly studies early anti-cracking of cementitious composites containing polyvinyl alcohol (PVA) fiber and fly ash (FA). The PVA fibers were added at the volume fractions of 0%, 0.25%, 0.5%, 1.0% and 2.0%. The percentages of FA used in the experiment were 0% and 15%. Experimental results show that the maximum crack width and total crack area can be reduced with the increase of volume fraction of PVA fiber, and that no crack appeared at the volume fraction of 2.0%. The reducing tendency of crack width and total crack area kept constant with addition of FA, but reducing amplitude decreased. When the PVA fiber volume fraction remains constant, the early anti-cracking properties of cementitious composites containing PVA fiber and common cement are superior to one containing PVA fiber and FA. Conclusions can be drawn that the early anti-cracking properties of cementitious composites can be improved by PVA fiber.

Abstract: It is common to control the Frequency-variable air conditioner (A/C) by using PID controller. However, an arithmetic based on artificial immune system was proposed. The immune system of organism was analyzed, and an architecture of the arithmetic was designed. The A/C behaviors were expressed by antibodies, a concentration model of antibody was built, and rules of A/C behaviors could be obtained by the antibody concentration. the initial immune response arithmetic and the secondary immune response arithmetic were designed, which were used to memorized normal behaviors and detect abnormal behaviors. Experiments show that the scheme is capable of adapting to system variation. The system can obtain the stable condition with good convergence even high temperature of 45°C

Abstract: Ni-base alloy coatings on carbon steel surface were prepared by electro-spark deposition technology and the characterization and tribological behavior of the coatings were investigated. The research results show that the microstructure of Ni-base alloy coating can be divided into three typical areas: the white alloy zone, transition zone and overheating-affected zone. The hardness across the interface of the coating and substrate, in which chemical elements transferred from the coating to substrate, gradually decreases with the depth away from the coating surface. The friction coefficient slightly decreases, while the wear loss increases with the increase of load. The main wear mechanism of the coating is micro-cutting wear at light load friction, and gradually changes into mixture of micro-cutting wear, multi-plastic deformation wear and adhesive wear at heavy load friction.

Abstract: In order to improve the grinding performance and service life of electroplating composite coatings with high percent of hard abrasives, the composite coatings of Ni-Co/SiC were prepared by occlusion electroplating technology and their microstructure and tribological properties were studied. The research results show that the cathodal electric-current density in occlusion electroplating process and the SiC abrasive size have great influence on microstructure and tribological properties of Ni-Co/SiC coatings. The optimum value of cathodal electric-current density is 1 A/dm2 and the proper SiC abrasive size is about 20 μm, in which the Ni-Co/SiC coatings have excellent wear resistance and high grinding ability. The main wear mechanisms of Ni-Co/SiC coatings are micro-cutting and adhesive wear of matrix alloy, and micro-cracking wear and spalling of SiC abrasives.