Use of La2O3 with 8YSZ as thermal barrier coating and its effect on thermal cycle behavior,microstructure, mechanical properties and performance of diesel engine operated by hydrogen-algae biodiesel blend

In this present work, the effect of lanthanum oxides (La₂O₃) on the thermal cycle behavior of TBC coatings and mechanical properties such as adhesion strength and microhardness of 8% Yttria Stabilized Zirconia (8YSZ) TBCs were investigated. CoNiCrAlY and aluminium alloy (Al–13%Si) were used as bond coat and substrate materials. 8YSZ and different wt % of La₂O₃ (10, 20, and 30%) top coatings were applied using the atmospheric plasma spray (APS) method. The thermal cycling test for TBC coated samples were conducted at 800 °C in the electric furnace. The XRD pattern shows that the La₂O₃ doped 8YSZ material transformed to cubic pyrochloric structured La₂Zr₂O₇ during thermal cycling. Further, the Taguchi-based grey relation analysis (GRA) method was applied to optimize the TBC coating parameters to achieve better mechanical properties such as adhesion strength and microhardness. And the optimized La₂O₃/8YSZ TBC coating was coated on CRDI engine combustion chamber components. The engine was tested with microalgae biodiesel and hydrogen, and the results were promising for the TBC-coated engine. The engine performance increased while using La₂O₃/8YSZ coated components, and the emissions from engine exhaust gas such as CO, HC, and smoke reduced considerably. It was found that there was no separation crack and spallation of the coating layer in the microstructure. Ultimately, the microstructural analysis of the optimized TBC coated piston sample after 50 h of running in the diesel engine confirmed that the developed coating had a superior thermal insulation effect and longer life.     

Harmonic power distortion measurement in Park Plane

Harmonics free system voltage or currents form a closed loop in voltage–voltage or current–current plane. In this loop cleavages appear with the presence of harmonics, order of which is directly proportional to number of cleavages. Reactive and active power of the system are related with the area in v–i and vi–t planes covered by the curves consisting of fundamental waveform along with harmonic components, wherefrom, active power and reactive power distortion factors have been measured to assess power quality in a three-phase power system. Park transformation technique has been used for power distortion factor measurement, which has reduced the computational effort to a great extent.     

Fault diagnosis in six-phase induction motor using a current trajectory mass center

This paper proposes a new methodology for diagnosing the occurrence of stator winding faults in the six-phase induction motor. The proposed approach uses the xy current trajectory mass center of the motor stator currents. The Park transform is applied to the acquired induction motor stator currents. This transformation allows obtaining specific patterns that are used to identify stator winding faults. For healthy motors, a single point in the xy-plane is obtained. However, for a motor with a stator winding fault a circle is obtained, whose radius is related with the severity of the fault. To identify these patterns an algorithm, entitled current trajectory mass center, was developed. A theoretical analysis of the six-phase motor in αβ and xy current coordinates, for healthy and stator fault operation modes, is also presented. In order to show the applicability of the proposed technique several simulation and experimental results are presented.     

Uncertainty estimation of a liquid flow standard system with small flow rates

A liquid flow standard system is used to calibrate liquid volume of fuel–oil flow meters at small flow rates between 50 L/h and 700 L/h. However, the system has not been used to calibrate volume flow rate because the system is only operated with the standing-start-and-finish mode. In this study, the liquid flow standard system was rebuilt to provide a calibration service of volume flow rate by attaching two flow diverters, which can operate the system with the flying-start-and-finish mode. To evaluate its performance for volume flow metering, several techniques were introduced. First, diverter timing errors were estimated by linear regression. Second, covariance between buoyancy correction factor and water density was obtained to consider interdependency between the two measurands. Third, calibration and measurement capability (CMC) was evaluated by setting a fixed value of collected weight or elapsed time for flow diversion. Finally, several CMCs were compared to find the best measurement condition. As a result of the above approach, the CMC of the liquid flow standard system was found to be (0.10–0.52)% (k = 2) for (50–700) L/h with a minimum collected weight at 10 kg.     

Flaw detection and measurement for 4K Ultra HD thin-film-transistor array panel

Display pixels of liquid-crystal-display televisions (LCD TVs) on thin-film-transistor (TFT) array are getting smaller. This paper introduced the method of voltage imaging technique, which developed and provides initial insight into the thin-film-transistor array flaw detection and measurement for ultra-high-definition (Ultra HD, UHD) LCD TV application. We proposed the measurement of flaw detection, based on TFT array testing and characterization with respect to opto-electric transformation measurement.     

Understanding low cycle fatigue and creep–fatigue interaction behavior of 316 L(N) stainless steel weld joint

The aim of this work is to study the time dependent effects on the low cycle fatigue (LCF) behavior of 316 L(N) stainless steel weld joint. Influence of strain rate, temperature, strain range, hold time and hold duration on fatigue life is evaluated. Occurrence of dynamic strain aging, creep damage, overall distribution of damage across the weld joint and the role of microstructure on the failure mode and failure location of the weld joint is discussed as a function of test parameters.     

Numerical investigations of developing flow and heat transfer in raccoon type microchannels under inlet pulsation

The present study investigates numerically the simultaneously developing unsteady laminar fluid flow and heat transfer inside a two dimensional wavy microchannel caused by a sinusoidal varying velocity component at an inlet. The flow was both thermally and hydro dynamically developing while the channel walls were kept at a uniform temperature. The simulation was performed in the laminar regime for Prandtl number 7(water) and Reynolds number ranging from 0.1 to 100. A Wavy microchannel having non-dimensional hydraulic diameter 1 with varying pulsating amplitude and frequency represented by the Strouhal number was designed for the given Reynolds number range. Based on the comparison with steady flow in a wavy channel it was found that imposed sinusoidal velocity at the inlet can provide improved heat transfer performance at different amplitudes (0.2, 0.5, 0.8) and frequencies (1, 5, 10) while keeping the pressure drop within acceptable limits.     

The TTP Transonic wind tunnel Mach number uniformity analysis

The distribution of the Mach number in the test section of the Brazilian Pilot Transonic Wind Tunnel was evaluated for the subsonic, transonic and low supersonic regimes. A convergent–divergent nozzle was designed and manufactured to increase the TTP envelope up to Mach number 1.3. Static and total pressures of the airflow are input quantities for the isentropic equation used for Mach number estimation. Static pressure measurements at the test section stations are accomplished by a centreline pressure probe and by distributing pressure taps along the upper and lower walls. Data reduction includes the evaluation of the uncertainties associated with the measured quantities, as well as their propagation to the output quantity, by employing the Monte Carlo method. Least squares fitting is applied to the experimental data in order to supply Mach number calibration curves. Sources of error causing non-uniform flow for Mach number equal to 1.3 are pointed out.     

Buckling analysis of stiffened plates subjected to non-uniform biaxial compressive loads using conventional and super finite elements

This paper presents the buckling analysis of stiffened plates, using both conventional and super finite element methods. Mindlin plate and Timoshenko beam theories are utilized so as to formulate the plate and stiffeners, respectively. The arbitrary oriented stiffeners can be positioned anywhere within the plate element and are not limited to be placed on nodal lines. Therefore, any configuration of plate and stiffeners can be modeled. Furthermore, extensive boundary conditions as well as general in-plane loading conditions can be considered using the proposed method. As the applied in-plane loads are not uniform, the buckling load is evaluated in two steps. First, the elasticity problem is solved to determine the stress distribution in prebuckling stage. Applying the principle of minimum potential energy, based on derived stress distribution, yields to the buckling equation of stiffened plates. Numerical examples are proposed to study the accuracy and efficiency of the developed super elements. Effects of various combinations of biaxial loads along with different boundary conditions on buckling characteristics of stiffened panels are also investigated.