Synthesis of nanoparticles using plant extract is a cost effective, green and eco-friendly technology beside beingavailable for large scale production. The phytochemicals present in plant extracts may act as reducing andstabilizing agents for the synthesis of nanoparticles in plant extracts. In the present work, silver nanoparticleshave been synthesized using aqueous olive tree extract. The synthesized nanoparticles were characterized withUV-Vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The existence ofpeak (absorption maxima) at 429 nm confirms the formation Ag nanoparticles in the extract. According to XRDpattern, the synthesized AgNP’s have fcc crystalline structure. It was also found that the size of silvernanoparticles synthesized was 6.0 ± 4.0 nm and spherical.
In this paper, surrogate based global design optimization strategies have been illustrated for application problems in engineering. In order to simulate this complex behavior realistically, automotive crash for example involves simulation and modeling of complex non-linear behavior. These non- linear phenomenons includes simulation of very large deformations, non- linear material and contact modeling with Finite Element Analysis (FEA). Even with today’s increased computational power, the solution time has increased substantially with increasing model complexity. The Kriging model is used as surrogate model for the modeling the objective function and constraints used in the FE model. Genetic Algorithm (GA) is used to estimate the model parameters of Kriging. The global optimization is achieved by infill points based on maximizing the constrained expected improvement criterion. For the applications of these techniques a constrained cantilever beam problem and frontal crash simulation on partial car body is illustrated.
The efficiency of the flat-plate and U-tube solar collector was investigated and analyzed experimentally as a function of the concentration of Al2O3nanofluid. When Ti = Ta, the efficiency of the flat-plate solar collector with 1.0 vol%-Al2O3nanofluid was 70.9%, which is the highest value and 16.2% higher than that with water. Besides, the maximum efficiency of U-tube solar collector was 67.6%, which is a 16.3% higher than that with water. In this study, the efficiency of the solar collector with 1.0vol%-Al2O3nanofluid was the highest. In addition, the flat-plate solar collector had a higher maximum efficiency than U-tube solar collector, but the decrease of efficiency of flat-plate solar collector was much steeper than U-tube solar collector because of a higher heat losses.
Rajkumar B. Patil, Basavraj S. Kothavale, V. K. Tripathi
Reliability is widely recognized as a critical design attribute for most of the industrial systems. In recent papers, various types of analysis of CNC assisted systems are conducted using binary state system approach. In this paper, reliability analysis of CNC turning center is presented using multi-state system (MSS) approach. The field failure database has been used for the statistical analysis. The failures of the CNC turning center are classified into three degraded states, one failed state and one fully operational state and thus provide more insights through finer resolution into the degradation behavior of the system and its propagation towards complete failure. This work highlights the importance of conducting multi-state (MS) failure analysis of any engineering system when seeking to understand its failure behavior.
Experiments in laminar lifted nitrogen-diluted propane coflow-jet flames were performed to investigate distinct differences between buoyancy-driven self-excitation (BDSE) and Lewis-number-induced self-excitation coupled with heat loss near flame extinction (LISE_CHL) in normal- and micro-gravities. The flame stability map with 9.4 mm nozzle diameter was presented as the functional dependency upon fuel mole fraction XF,O and nozzle exit velocity UO. The results showed that only the BDSE was observed. Further experiments were conducted with 0.95 mm nozzle diameter (buoyancy-suppressed), and the flame stability map was also presented. Two self-excitations existed separately when the helium mole fraction XHe,coflow in coflow-air varied in the range of 0.1 to 0.2. The two self-excitations had different characteristics in flame dimensions with time (flame width, and flame tip and base lengths) and phase diagram of effective Damköhler number versus light-off height. The BDSE was observed at relatively larger XF,O; meanwhile, the LISE_CHL was at smaller XF,O. Both the self-excitations were characterized with different functional dependencies of Strouhal number upon their related physical parameters. The mechanism of LISE_CHL, caused by repetitive interaction between burning rate and heat loss from premixed wings to trailing diffusion flame in addition to Lewis number larger than unity, was suggested. Further confirmation on both self-excitations was made through microgravity experiments using a 10 m drop tower.
Heat treatment processes such as case hardening are performed on critical machine components such as gears to increase its wear resistance. During this process distortion occurs which causes significant cost impact to the manufacturer, because distorted components are often need to be hard-machined after heat treatment. Distortion can be significantly reduced by using low pressure carburizing (LPC) and high pressure gas quenching (HPGQ) techniques. HPGQ provides a very uniform heat transfer coefficient. In this study LPC and HPGQ processes are simulated using ABAQUS software for a spur gear and distortion is calculated.
The paper presents an active vibration control of Timoshenko smart beams using finite element approach. Smart beam is modelled by Timoshenko beam theory considering the effects of rotational inertia and shear deformation. Single input-single output and multiple input-multiple output active control systems have been considered. A linear, quadratic regulator controller based on optimal control theory is utilized for the vibration suppression of the smart beam. The output responses of both the systems with controller are effective and efficient to suppress the active vibration of the smart beam. However, to control the vibration, the later system has more effective than the first.
In current range of commercial vehicle air compressors, there is a need for development of more competent and complex designsdue to increase in competition. The reciprocating air compressors play an important role to supply air for brake actuation as well as suspension systems. In this paper, mathematical models are prepared for parametric study of kinematic and dynamic characteristics of piston-crank mechanism .An alternative approach of Rigid body dynamics simulation of this mechanism in ANSYS software is presented and validated through analytical models and experimental results. The thrust forces and moments obtained from rigid body analysis are used to perform static FEM analysis of various parts for stress evaluation. This RBD-FEM approach is widely established for IC engine cranktrains but less work is done regarding air compressors. This new simulation methodology for reciprocating compressors proves useful for designers to verify new designs and take better design decisions.