Advanced Materials Research Vols. 189-193

Abstract: Using time series model, isometric transformation time series model and ARTAFIT model, we deal with acoustic signal, obtaining different sets of parameters according to different acoustic signals. We use support vector machine (SVM) to recognize different acoustic signals by analyzing different sets of parameters. When the parameter set is too large, we should first reduce order making use of principal component analysis (PCA), then we can recognize them using support vector machine. In the end, we give a case study, which indicate the results of applying our models are satisfactory.

Abstract: Diffusion bonding of ZrB2 ceramic and Al-Sn-Mg alloys was carried out at atmosphere. The Al-Sn-Mg alloys were Al-xmass%Sn-ymass%Mg (x=0, 0.5, 1.0, 2.0; y=0, 0.5, 1.0, 2.0). ZrB2 ceramic was fine ZrB2 type. The bonding conditions were 873K for 3.6ks, 7.2ks and 14.4ks under the pressure of 1MPa, 2MPa and 4MPa. The microstructures of the bonding interface and the shear fracture surface were investigated by SEM and EPMA. The bonding strength was examined with the shear fracture test. The results show that ZrB2 ceramic could be joined to Al-Sn-Mg alloy with diffusion bonding. “Al-Sn” alloy can be used as an interlayer for diffusion bonding of ZrB2 ceramic. And the optimum “Al-Sn” alloy is Al-0.5Sn-0.5Mg. Shear strength of 42~44 MPa can been obtained for ZrB2/Al-0.5Sn-0.5Mg joint bonded at 873 K for 7.2 ks, 14.4 ks under 2 MPa, 4 MPa.

Abstract: Dissimilar metals joints between aluminum and zinc-coated steel were joined by CMT machine with ER4043 filler metal. The microstructure and mechanical properties of the joints obtained with different heat input were analyzed. The results showed that the thickness of interfacial intermetallic compound was determined by the welding heat input. Tensile specimens were broken in HAZ of aluminum base metal and the tensile strength of the joint can reach 122.3MPa.

Abstract: By determining membership function of the input parameters and selecting defuzzification method, the evaluation model which can be used to intelligent analyzing the causes of SMT solder joint defects was set up. The fuzzy neural network was trained by using the output variables of the training samples from intelligent discrimination as the input variables of training samples of fuzzy neural network. The fuzzy neural network was tested by using the output variables of the testing samples from intelligent discrimination as the input variables of testing samples of fuzzy neural network. The results show that by using the evaluation model the cause of SMT solder joint defects can be analyzed intelligently and the results of intelligently analysis are reasonable, the evaluation model can be used practically.

Abstract: This paper brought forward an intelligent computer aided instruction (ICAI) modeling method oriented to parallel robot instruction. According to the learning-origin structure of mechanical specialty students, the study process and cognition characteristics were analyzed, and the comparative research on their quality performance in parallel robot direction was carried out. The ICAI model was established oriented to parallel robot practical instruction combining machine learning and artificial intelligence method. Aiming at the basic instruction requirements of mechanical engineering specialty, the innovation mechanism of this area was researched, and the instruction strategies optimized and realization method were provided. Experiments proved that this method can simulate the implementation course of parallel robot instruction, and improve the instruction effects validly.

Abstract: Titanium alloy TC1 and Aluminum alloy LF6 were jointed by friction stir welding (FSW), and the influence of process parameters on formation of weld surface, cross-section morphology and tensile strength were studied. The results show that, Titanium and Aluminum dissimilar alloy is difficult to be joined by FSW, and some defects such as cracks and grooves are easy to occur. When the rotational speed of stir head(n) is 750r/min and 950r/min, the welding speed(v) is 118mm/min or 150mm/min, a good formation of weld surface can be obtained, but the bonding of titanium/aluminum interface in the cross-section of weld joint is bad when n is 750r/min which results in a low strength joint. When n is 950r/min and v is 118mm/min，the strength of the FSW joint of Titanium/Aluminum dissimilar materials is 131MPa which is the highest．

Abstract: Nanoindentation technique was employed to study the hardness and elastic modulus for different regions in the welded joint of high strength steel. And the variation in mechanical behavior at micro scales was analyzed combined with microstructure observation. Experimental results showed that both maximum hardness (4.11GPa) and maximum elastic modulus (210.3GPa) were obtained in the coarse grained HAZ and the corresponding microstructure was granular bainite. While the weld metal and fine grained HAZ had similar values of hardness and elastic modulus, and corresponding microstructures were acicular ferrite and polygonal ferrite respectively.

Abstract: Modern educational technology is widely used in college, modern educational technology application develop from simple slideshows, projection to the multimedia and network teaching, long-range education teaching, ect. The application of multimedia and network technology have positive significance in the teaching reform of cultivating student's quality , and skill training, and the creative thinking ability . Modern multimedia educational technology university plays an important role in promoting the level of teaching work and improving the quality of the education. The process of education and teaching which implements the mathematics education teaching through the application of modern educational technology curriculum, can improve math courses and teaching quality effectively. This paper explores the truth than using the modern education technology to improve education quality of teaching mathematics course. To realize mathematics teaching from the optimization, and extensive mathematics curriculum multimedia teaching, and explore the new mathematics curriculum teaching network technology actively, this paper discussed the application of multimedia technology to improve education in modern mathematics curriculum teaching quality.

Abstract: A new attempt is proposed to improve the load-carrying capacity of high strength steel undermatching butt welded joints by shape design. Based on the principle that reasonable geometric parameters designs of welded joints can regulate the distribution of stress and strain, reduce the stress concentration factors in low strength weld zone, the geometric parameters of undermatching butt joints, such as weld toe radius, height of excess weld metal and width of the cover passes are designed. A series of tests were completed to investigate the effect of weld shape design on the mechanical properties and security of undermatching butt joints. The results showed that the critical crack sizes of the 0.6~1.0 undermatching joints is greater than or equal to the one of base metal, the joints strengths approach to the tensile strength of base mental, and the fatigue strength is far higher than that of the as-welded equalmatching butt joints.

Abstract: Joining by forming of magnesium alloy is a kind of high-efficient joining method, but it’s restricted because of the limited formability of magnesium alloy at room temperature. According to the present status of joining by forming of magnesium alloy, the relative proposing solutions by using the contradiction matrix of TRIZ are given. The practice shows that dieless clinching solution is effective, and then the improvement program which also can decrease the pre-heating time considerably is presented. After analyzing, the result shows that the program is feasible.