Abstract: Gregory’s decomposed theorem of isotropic plate is extended to investigate torsional circular shaft for two-dimensional dodecagonal quasicrystal (2D dodecagonal QCs)with homogeneous boundary conditions, and the theory of equivalence that Cheng’s refined theory and Gregory’s decomposed theorem is extended to the cylindrical coordinate. The decomposed theorem of torsional circular shaft of 2D dodecagonal QCs with homogeneous boundary conditions is proposed on the basis of the classical elasticity theory and stress-displacement relations of 2D dodecagonal QCs without ad hoc assumptions. At first expressions are obtained for all the displacements and stress components in term of some 1D functions. Using Lur’e method, the exact equations were given. And the exact equations for the torsional circular shaft on 2D dodecagonal QCs without surface loadings consist of four governing differential equations: two harmonic equations and two transcendental equations.
Abstract: Contactless electroreflectance（CER）spectra of c-plane ZnO bulk have been measured from 20 to 300 K. Photoreflectance（PR）spectrum of ZnO bulk has also been measured at 300 K. The CER spectrum is red-shifted with respect to the PR spectrum at 300 K. It is known that the average field experienced in the CER is larger than that of the PR. In addition, the features of PR or CER is blue-shifted when the field becomes larger if they belong to band-to-band transitions. Hence, the observed features are excluded from band-to-band transitions and are attributed to excitonic transitions. The CER spectra were then fitted by Lorentzian profiles. The energies of the A（B）, B（A）, and C excitonic transitions at 0K, which were obtained by the best fit of Varshni’s equation, are 3.419, 3.436, and 3.482 eV, respectively.
Abstract: The experimental observation reveals that the influence of gas metal arc welding process on physical properties. The specimen was carbon steel ss400 grade sheet of 6 mm. The experiments with 23 factorial design. The factors used in this study are voltage at 20 and 23 V, travel speed at 5 and 7 mm/sec and wire feed rate were set at 80 and 110 mm/sec. The welded specimens were tested by penetration, width of weld metal and high of weld metal. The result showed that the voltage, travel speed and wire feed rate had interaction on penetration, width of weld metal and high of weld metal at 95% confidential (P value < 0.05). Factors affecting the penetration are the most voltage of 23 V, travel speed 7 mm/sec and wire feed rate 110 mm/sec. were penetration of 31.68 mm. The width of weld metal was most at 9.9 mm. on voltage of 23 V, travel speed 5 mm/sec and wire feed rate 110 mm/sec. The factors affecting the high of weld metal are most voltage of 20 V, travel speed 5 mm/sec and wire feed rate 110 mm/sec. were penetration of 4.51 mm. This research can bring information to the foundation in choosing the appropriate parameters to gas metal arc welding process.
Abstract: The research was study the effect of gas metal arc welding process parameters on mechanical property. The specimen was carbon steel ASTM A285 grade A which thickness of 6 mm. The experiments with full factorial design. The factors used in this study are shielding gas and voltage. The welded specimens were tested by tensile strength testing and hardness testing according to ASME boiler and pressure vessel code section IX 2007. The result showed that both of shielding gas and voltage had interaction on tensile strength and hardness at 95% confidential (P value < 0.05). Factors affecting the tensile strength are the most carbon dioxide and 27 voltage were tensile strength 213.43 MPa. And hardness maximum of 170.60 HV can be used carbon dioxide and 24 voltage. This research can be used as data in the following appropriate parameters to gas metal arc welding process.
Abstract: Bioactive glasses based on SiO2-CaO-P2O5 system have been synthesized by sol – gel process. The powder glass obtained has been characterized by X-ray diffraction, X-ray fluorescence spectroscopy (XRF), and Fourier transform-infrared spectroscopy (FTIR). In vitro study reveals formation of apatite layer at surface of powder glass, after 3 days of soaking in simulated body fluid.
Abstract: Brake pads are important safety devices in vehicles. An effort to avoid the use of asbestos in brake pads has led to the development of asbestos-free brake pads that incorporate various organic and inorganic fillers. Palm slag as a filler in brake pads was investigated in this paper. Different processing pressures were employed during production of samples through compression molding. The properties examined included hardness, compressive strength, and wear behavior. The results showed that brake pad samples prepared with 60 tons of compression pressure resulted in the most desirable properties. Hence, palm slag has its own potential for use as a filler in asbestos-free brake pads.
Abstract: An Mg-Li-Al-Zn-Sn alloy was prepared by vacuum melting. The actual content of the elements in the alloy was determined using inductively coupled plasma-atomic emission mass spectrometry (ICP-AEMS). The density of the alloy was detected using Archimedes’ method. Extrusion and rolling deformation were carried out on this alloy. Its microstructures and mechanical properties were then studied with an optical microscope (OM), scanning electronic microscope (SEM), X-ray diffractometer (XRD), energy dispersive spectrometer (EDS), and tensile tester. The extruded alloy was composed of α-Mg and Mg2Sn phases and had good strength and elongation properties as well as a good comprehensive performance. After further rolling deformation, an Al-Li phase appeared due to atomic diffusion during the hot rolling process. Strain-hardening and the strengthening effect of the Al-Li phase further improved the strength of the alloy but decreased its elongation capacity.
Abstract: This paper reports the design of a tunable radio-frequency (RF) inductor and analyses the parameters that influence the quality factor (Q) of the inductor. In our paper we mainly discuss the influence of the thickness of the metal layer on the Q when other parameters are fixed. In order to achieve the high thickness, we use SU-8 as our photoresist instead of the traditional photoresist. Through the analysis, we calculate out the thickness of the metal layer is 23um when the Q reaches to maximum.
Abstract: Density functional theory (DFT) calculations are performed to investigate CO bonded on the AunS (n=1~6) bimetallic clusters. It is found that the adsorption energies of CO on the AunS(n=1~6) clusters are greater than those on the pure Au clusters of corresponding sizes. This means that doped S atom can enhance CO adsorption on the Au clusters. Furthermore, through the Mulliken population analysis, we can see that charges transfer from the Au clusters to S atom, while charges donate to the Au clusters from the CO in CO/AunS sytem.