Abstract: Films of pure and doped Polyvinyl alcohol (PVA) with different concentration of Nickel Chloride (NiCl2) were prepared using the casting technique, in order to investigate the effect of NiCl2 additions on the optical properties of PVA host. The dispersion studies of pure PVA film and PVA films doped with NiCl2 were studied using complex refractive index in the wavelength range 190-1100 nm. The absorption spectral analysis showed that the optical energy band is due to the direct and indirect allowed optical transitions. The optical energy band gap Egopt of the films decreases with increasing NiCl2 contents, while the Urbach energy ∆Et called the width of localized states in the optical band gap decreases from 0.7414 to 0.1891 eV. The reductions of optical energy band gap were observed for all samples after annealing at temperatures 70oC for three hours.
Abstract: This paper determine the maximal torus of filiform Lie algebra to prove whether they are completable or not, and a sufficient and necessary condition for a filiform Lie algebra to be completable can be obtained.
Abstract: Based on the heuristic nonlinear creep model, the nonlinear coupled differential equations of the motion of a 12 degree-of-freedom (12-DOF) bogie system which takes account of the lateral displacement, vertical displacement, the roll angle and the yaw angle of the each wheelset and the bogie frame, moving on curved tracks are derived. The nonlinear creep forces and moments are constructed via the saturation constant of the nonlinear creep model in completeness. The effect of the suspension parameters of a bogie system on the derailment quotient is investigated. Results obtained in this study show that the derailment quotient of a bogie system increases as the vehicle speed increases. In addition, the derailment quotient of a bogie system is generally decreased with the increasing values of suspension parameters.
Abstract: This Abrasive Water Jet Machining (AWJM) process is usually used to cut the materials which are difficult to cut by conventional machining processes. In this work, controlled depth milling (CDM) is done using AWJM. This work primarily focuses on controlling the abrasive flow rate to reduce the time for machining the component. Here, an experimental setup is made with a modified attachment for abrasive feed system to machine stainless steel. The work also investigates the surface morphology, tolerance on depth of machining and surface waviness for the modified setup. With change in mass flow rate of abrasive, the traverse speed may also be altered and its effects on the machining time are controlled. This work also employs Non-destructive Testing (NDT) method i.e. ultrasonic flaw detector to find out internal defects and cracks in the milled material.
Abstract: Welded structures are frequently used in today’s metal industry. Since fatigue is still one major reason of failures, investigation in this field is of interest to engineers. In this study experimental methods are employed to perform a fatigue evaluation concerning local weld geometry. The emphasis was on quantifying the weld toe radius as a feature in quantification of weld quality. Three different welding positions which have been led to different toe radii were analyzed. Each batch contained 12 specimens manufactured in cruciform joint and has been tested in non-load carrying status. Finally, the results of tests were compiled in Wöhler (S-N) curve and compared to reference curves introduced by IIW (International Institute of Welding). Results of this study show that local weld geometry has remarkable influence on strength of welded structures. It can be concluded that specimens with larger toe radii had more fatigue strength – as it was expected from the theory.
Abstract: A novel design of a simple square-frame USM (ultrasonic motor) was proposed. The stator of the motor consists of a square-frame shape elastic body and four rectangular plate ceramics. The four ceramics were attached to outer surfaces of the square-frame elastic body. The same phase voltages were applied to the ceramics on horizontal surfaces, and 90 degree phase difference voltages were applied to the ceramics on vertical surfaces. When the four outer edges of stator were clamped, the bending vibrations of the right angled bars were transformed into travelling vibrations and elliptical displacements were generated at the center of the bars. To find an optimal size of a stator, that generates elliptical displacement at the centers of the inner surfaces, the finite element analysis program ATILA was used. The analyzed results were compared to the experimental results. As result, the model EL10W3T0.5_CL7 which generates the maximum elliptical displacement was chosen by analyzing the resonance mode according to changes in frequency.
Abstract: Structure of a cantilever-type unimorph piezoelectric generator was proposed and designed so as to allow the generator to resonate at frequencies lower than commercial frequencies. This generator is capable of generating amount of voltage its despite low frequency and simple fabrication that result from its simple structure. In this paper, the resonance characteristics of the generator depending on significant parameters were determined through a modal analysis and the influence of each parameter was analyzed to define each its level of sensitivity on the high output characteristics using ANSYS, a FEM program. The generators resonated at frequencies lower than 60 [Hz], as determined through the FEM results. The generating characteristics were then defined by implementing vibration experiment and comparing the results with those from the analysis. The resonance frequency and output power depending on changes in the mass and material were determined by the analysis.
Abstract: In this study, Magneto-rheological (MR) fluid was modified by mixing and adding the additives. The researches on MR fluid have been active progress all around the worlds, especially for the application to many devices on the various fields. For the success of application, tribological characterisitcals are important to be satisfied. There are many progress mainly aimed to the methods to improve the stability and performance of MR fluid in application. In this study, the experiments on friction and wear with pin-on-disk tester as well as SRV tester are conducted in different operation and magnetic. From the results, tribological performance of modified MR fluid is analyzed.
Abstract: The effect of temperature-dependent thermal conductivity on the magneto-convection in a low Prandtl number liquid is investigated numerically. The liquid is contained in a closed square cavity with isothermal vertical walls kept at different temperatures. The top and bottom walls are assumed to be insulated. To solve the governing non-linear differential equations (mass, momentum and energy) a finite volume code based on SIMPLER algorithm is utilized. The results for different Rayleigh numbers (Ra), Hartmann numbers (Ha) and temperature coefficient of thermal conductivity (η) are presented in form of streamlines, isotherms and Nusselt number. It is found that the heat transfer decreases appreciably across the cavity with a decrease in thermal conductivity. It is observed that at low Hartmann number (Ha=30) the thermal boundary layer is formed near the side walls and as η increases the thickness of these boundaries decreases. Also it is found that as non-dimensional thermal conductivity increases the peak of velocity profile increases; however, this phenomenon is very weak at high Hartmann number.
Abstract: To improve passing topography capacity of 2WD truck on soft soil, A track device circling driving wheel (TDCDW) is developed and tested. Tests are conducted on sandy loam to determine the traction performance of the TDCDW. The drawbar pull and the slip of the 2WD truck with TDCDW are measured by the dynamometer vehicle. The soil resistance of 2WD truck with TDCDW is got by pulling the wire rope fixed on truck with the winch and reading the load cell fixed on the wire rope. The main results of this study are: The load on the front wheel has no influences on the tractive effort of TDCDW on sandy loam. The slip of the vehicles with the TDCDW is not the simple assembled slip of wheel on TDCDW and TDCDW on sandy loam. When the load is the same, the maximum tractive effort of truck with TDCDW is equal to the maximum tractive effort of tracked vehicle with the same contact area on sandy loam.