Abstract: A nanostructured surface layer is formed on 2219 Al alloy plate by means of supersonic fine particles bombarding (SFPB). The surface microstructure formation mechanism of morphology change is systematically characterized by using scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average grain size of 30nanostructured layer is about 30 nm when the surface of sample is induced by severe plastic deformation. Based on the experimental observations, nanoscale dislocation cells exist in strain layer about 200 from the surface, and we put forward a new formation mechanism of Al alloy surface nanocrystalline layer through theoretical analysis. The original grain is segmented fast into nanoscale dislocation cell or lamellar cell. As the Burgers vector of cell walls continue to accumulate, grain orientation difference constantly increases to form the nanoscale subboundary. Eventually, equiaxed nanocrystallites with random crystallographic orientations are formed by grain rotating or grain boundary sliding.
Abstract: An investigation has been done to study the effect of heat treatment at low temperature on the development of mechanical and electrical properties of the industrially cold drawn aluminum alloy wires (6101). This aluminum alloy is used by the national company of electric cables of Biskra (ENICAB) for the transmission lines of electrical energy. The mechanical and electrical properties of the Al-Mg-Si alloys can be changed by heat treatment. Different technical procedures have been used In order to understand the complicated effect of aging on 6101 aluminum alloy; we have used the optical microscopy, hardness measurements and the electrical resistivity measurement. It was noted that the cold drawing of this aluminum alloy increase the microhardness which is produced by a high strain hardening of the material accompanied by a development of a fibrous texture. We notice also that the electrical resistivity of the alloy increase with an increase of the deformation level and decrease of this properties with the increasing aging time at 170 ° C.
Abstract: Graphene oxides are known for their affinity towards ionic components. Hence this property could be utilized to remove the impurities present in water molecules. Moreover, Graphene oxides are popular for their antimicrobial and disinfective properties. Graphene nanocomposite was prepared with reduced sugar and sand mixture at nitrogen atmospheres at 200o C and was characterized using XRD, SEM-EDAX, UV- Visible spectroscopy and Raman’s spectroscopic techniques. Two different water mixtures were used for the purification purpose- ie., sewage and soft drink concentrate (Coca Cola). Graphene Sand Composite (GSC) was loaded for purification at different weight percentage compositions such as 1%, 3% and 5%. Water mixtures were analyzed for their chemical and physical properties before and after treatment with graphene nanocomposite. The microbiological load before and after treatment with the composite was also analyzed. All the characterization shows the presence of graphene functionalities, carbon functionalities, and other elements present in the GSC. The physical, chemical and microbial examination of purified coca cola and sewage water matches the features of pure water with less impurities and absence of pathogen. The current study reveals the importance of water purification application using GSC and the measurement of water purification efficiency with conventional techniques.
Abstract: The oil production industry in Nigeria operates both onshore and more recently offshore in the coastal areas located in the oil-rich Niger-Delta. Unfortunately, the drilling mud additives currently used in the country are all imported and at huge foreign exchange costs. Therefore the objective of the current effort is development of drilling fluid from locally sourced mud additives for drilling operations. Various rheological and filtration tests were carried out on both unbeneficiated and beneficiated local clay from Afuze, Nigeria using a six-speed Rheometer and API filter press respectively. Beneficiation involved the addition of sodium carbonate, caustic soda and starch to the mud formulations.Clay concentrations were varied from 20g/350ml to 60g/350ml. The test results showed that free swell volume (FSV) increased from with clay concentration with the optimum values observed at 60g/350ml. The filtrate loss of 63ml, filter cake thickness of 6m, yield point of 7cp and plastic viscosity of 1cp values of Afuze clay did not satisfy API specification of 15ml, 2m, 24cp and 8cp respectively at any tested concentration. Likewise Afuze clay did not display gel strength (10 seconds and 10 minutes of 29 and 34 respectively) suitable for bringing cuttings up from the hole. However, improvements in its rheological and filtration properties as well as free swell volume were observed with the beneficiated Afuze clay at clay concentrations of 20, 30, 40, 50, 60g/350ml when beneficiated with starch concentrations of 1g and 0.5g, sodium carbonate of 2g and 1g and caustic soda of 0.25g. Beneficiated Afuze clay displayed gel strengths (10 seconds and 10 minutes of 98 and 140 respectively) suitable for bringing cuttings up from the hole with optimum values observed at 60g/350ml.
Abstract: Optimum design in civil structures like domes and vaults is a very old and ongoing research field. These structures are preferably designed to transport loads via membrane action. In this paper, we have considered a reinforced concrete dome and vault, where the bending moment and strain energy were used as objective function to be minimized using genetic algorithm, and model reduction method by proper orthogonal decomposition based on the results of finite element analysis of gradually changed design parameters. The proposed approach results are of a high accuracy compared to finite element based optimization.
Abstract: In order to improve the efficiency of centrifugal pump, based on the bionics principle, established non-smooth surfaces of various groove structure on the centrifugal pump impeller. The internal flow field of it was numerically simulated through RNG k-ε turbulence model. Research the drag reduction characteristics of non-smooth impeller in different groove shape and arrangement. The results showed that the biggest drag reduction rate of centrifugal pump with non-smooth blades is about 6.22%. The blades of non-smooth unit can effectively inhibit the near wall boundary layer flow state, reduce the shear stress on blades wall, reduce the internal fluid turbulent degree of centrifugal pump, so that the fluid flow in centrifugal pump impeller is more stable, improve the efficiency of centrifugal pump.
Abstract: In the present work DEA (data envelopment analysis) coupled with Taguchi method has used for optimization in process parameters of hot turning operation. An experimental investigation has been carried out to study the effect of cutting parameters such as speed, feed and depth of cut during. The material removal rate and surface finish, are to be studied with respect to machining at 450 temperature by heating Inconel 625. In order to achieve both quality and productivity, optimization of both is necessary simultaneously. DEA –Taguchi method can employed for solving in multi-response problem. LINGO software was used to find out the relative efficiency and converted to S/N ratio using MINITAB software. The optimization of the machining parameter found at 100 m/min cutting speed, 0.15 mm/rev feed rate and 1 mm depth of cut. Depth of cut is the most influencing parameter which affect both surface finish and material removal rate in the machining process.
Abstract: This paper presents a desirability function approach in order to find out an optimal combination of Machining parameters for multi-response parameters in hot turning operation of nickel based alloy. Taguchi’s L9 orthogonal array is used for experimental design. The machining parameters such as cutting velocity, feed rate, depth of cut and temperature are optimized by multi-response considerations namely power, flank wear, and MRR. ANOVA test was carried out and it was found that cutting speed is most influence parameter followed by feed rate, depth of cut and workpiece temperature. The optimization of machining parameters was found at 5.8 m/min of cutting speed, 30 °C preheating temperature, 0.2 mm depth of cut and 0.15 mm/rev feed rate
Abstract: Calibration curves of a multi-component dynamometer is of essence in machining operations in a lathe machine as they serve to provide values of force and stress components for cutting tool development and optimization. In this study, finite element analysis has been used to obtain the deflection and stress response of a two component cutting tool lathe dynamometer, for turning operation, when the cutting tool is subjected to cutting and thrust forces from 98.1N to 686.7N (10 to 70kg-wts), at intervals of 98.1N(10kg-wt). By obtaining the governing equation, modeling the dynamometer assembly, defining boundary conditions, generating the assembly mesh, and simulating in Inventor Professional; horizontal and vertical components of deflection by the dynamometer were read off for three different loading scenarios. For these three loading scenarios, calibration plots by experiment compared with plots obtained from simulation by finite element analysis gave accuracies of 79%, 95%, 84% and 36%, 57%, 63% for vertical and horizontal deflections respectively. Also, plots of horizontal and vertical components of Von Mises stress against applied forces were obtained.
Abstract: This paper proposes a procedure based on a multi-phase seeker optimization algorithm (MSOA) for optimizing the commitment of transmission system. The under consideration problem is formulated with the aid of AC-based security constrained optimal power flow (SC-OPF) considering system constraints. The target is to detect transmission lines commitment schedule that reduces system production costs and enables sufficient reserve levels from both generation and transmission. The methodology is illustrated through several computational tests on IEEE 57 and IEEE 118 bus test systems to confirm the previous objectives. It is proven that numerical results based on the use the AC model demonstrate that the calculation time is short enough and the cost savings are reasonably better than DC power flow model. In addition, all transmission lines are preserved within their permissible boundaries and the voltage deviation is maintained at the least levels.