Abstract: In this paper, a new (novel) welding technology has been applied to join 0.1 mm thin plates. An initial study on the influence of welding current on the welding properties for stainless steel SUS304 plates is discussed in this paper. The weld bead appearance on both top surface and bottom surface was observed by microscope to indicate the change of weld bead size and welding defects. The results showed that by utilizing a constricted nozzle, a good weld bead is found out when the arc length is too short (0.3 mm), welding speed is very high (3000 mm min-1) and base metal is very thin (0.1 mm) with suitable welding conditions.
Abstract: The present study investigated the effect of operating parameters in modeling the output quality of welding process of steel sample. A three factor, three levels Box-Behnken Design (BBD) of RSM was applied to determine the effects of three independent variables (welding speed (A), welding current (B) and electrode potential (C)) on the tensile strength and to also develop a model for predicting the output quality. Data analysis shows that A, C, AB, BC, A2, B2and C2 are the terms which significantly affected the ultimate tensile strength of the sample at 95% confidence level. The experimental values were very close to the predicted values and were not statistically different at p<0.05. The maximum tensile strength of 228 MPa was obtained at 250 A current, electrode diameter of 3.25 mm and 50 cm/min welding speed, respectively. The regression model obtained has provided a basis for selecting optimum process parameters for the improving output quality (tensile strength) of the welded steel sample.
Abstract: The shear strength of 302 austenitic stainless steel spot welds has been studied. Thewelding current in resistance spot welding process (RSW) plays a significant role. However,this item's effect is well known and extensively studied in the previous literature. This work aims toshow the heat treatment’s effect on different joints that welded at various current. The experimentalresults show that the tensile shear strength is increased with increasing the current. Annealingtreatment improves the tensile shear strength due to the reformation of the grain size and removesthe residual stresses. Grain refinement is an effective technique for improving the strength.Therefore, the tensile shear strength is increased by annealing treatment temperature up to 750 °C.However, at 850°C, the tensile shear strength is dropped down.
Abstract: The self-conditioning of hydrophilic fixed abrasive lapping based on the principle of two-body (pad-wafer) abrasion has great importance on the MRR (material removal rate) of wafer. The physical and mechanical properties of pad were taken as set of available alternatives. Fuzzy comprehensive evaluation principle was applied to establish a model for the self-conditioning of FAP. The swelling ratio, the slurry abrasive ratio and pendulum hardness were selected to be the set of alternatives for self-conditioning evaluations in this paper .The five types of matrix formations of fixed-abrasive pad were prepared, and the matrix were ranked in order of comprehensive evaluation index. The results show that the fuzzy evaluation is rational. The tests of MRR verified the self-conditioning of FAP. The machining of pad can be evaluated in advance of lapping processes. Moreover, the self-conditioning evaluation will be important reference for determination of FAP during choosing the matrix formations.
Abstract: This paper addresses the development of a foot structure for 22-Degree of Freedom (DoF) humanoid robot. The goal of this research is to reduce the weight of the foot and enable the robot to walk steadily. The proposed foot structure is based on the consideration of cases where the ground reaction forces are set up in different situations. The optimal foot structure is a combination of all the topology optimization results. Additionally, a gait pattern is generated by an approximated optimization method based on Response Surface Model (RSM) and Improved Self-Adaptive Differential Evolution Algorithm (ISADE). The result is validated through dynamic simulation by a commercially available software called Adams (MSC software, USA) with the humanoid robot named KHR-3HV belonging to Kondo Kagaku company.
Abstract: One of the most important urban areas is street s and intersections that play an important role in shaping the overall identity of a city. The city is defined by the presence of the humans at night and nightlife plus visual sense plays the most important role in the perception of urban space. In addition, most of the things that are received by the sense of sight are with the help of light. Therefore, light and lighting in urban spaces as a non-physical element will have a huge impact on the quality of urban space. The main question in this study is the effects of lighting on the pedestrians’ understanding of the sense of security in Valiasr Street .In this regard, two variables of light color and light intensity are evaluated and considered based on eight hypotheses. To test these hypotheses, the main variables were first investigated and scrutinized. Then, according to the survey conducted, indicators related to the variables were determined and the items were designed. The main data collection tool is the questionnaire and among the pedestrians of Valiasr Street in Tehran that were selected as statistical population, 228 persons were randomly questioned. Due to the discrete nature of variables, a nonparametric function was used for their analysis. Calculation method using Kendall’s correlation analysis was analyzed using SPSS software. The findings show that that the satisfaction rate of light intensity is low, but their satisfaction with the lighting, light color, sense of security, and the ability to recognize faces is assessed averagely. Regarding the light color, people preferred white color to yellow one. The findings in this study suggest that using the white light instead of yellow and increase of light intensity increase the sense of security in pedestrians.
Abstract: In this study, the advantages and disadvantages of different immobilization approaches, proposed for a luminescent Hg2+chemosensor based in a spirocyclic phenyl-thiosemicarbazide Rhodamine 6G derivative (FC1), are analysed, and a comparative study of the different immobilization protocols is performed. The results demonstrated that the chemosensor is able to detect Hg2+ at ng mL-1 trace levels, with a remarkable selectivity, allowing its determination in biological, toxicological and environmental samples. Methyl methacrylate (MMA) and hydroxyethylmethacrylate (HEMA) polymeric film, electrospinning generated polymeric microfibres, nylon membranes and Au nanoparticles were tested as immobilization materials. The utilization of gold nanoparticles (AuNPs) is the method with the lowest limit of detection (LOD = 0.15 ng mL-1), but the response time is too high for practical use (7 hours). Nylon membranes give a very low detection limit (0.4 ng mL-1) and a practical response time (4 min), being the method of choice for practical applications to determine Hg2+ in aquatic, biological and toxicological samples, at a sampling rate of about 15 samples per hour.
Abstract: Numerical simulations have been performed to analyze the interaction of confined coaxial high-swirl jets in both cases: isothermal and reactive flows. Besides different setups of swirl injectors have been tested to study the influence of swirl in the flames for both stoichiometric and lean mixtures. The aim was to quantify the nitrogen oxide emissions as well as the flow pattern for different swirling annular air jet and non-swirling inner fuel jet. This simple setup is widely used in burners to promote stabilized flames of lean mixtures producing ultra low NOx emissions.
Abstract: The forest biomass of the province of Badajoz (southwestern Spain) is around 274,335 tons, which is equivalent to 112,000 toe of energy. Consequently, the quantification, analysis, and mapping of the energy potential from the residual biomass, considering the most important forestry species of the studied province, were performed. Moreover, the optimum locations of biomass logistics centers were established. Results of this study are within the value chain of biomass, regarding to the production, transformation, commercialization, and use of the existing biomass to generate energy, heat, and electricity.