Search

AbstractIn this research, the response of the RC Beam-Column Joint under the cyclic loads was analyzed with a FEM solver (Abaqus) by using various grades of Engineered Cementitious Composite (ECC) in the joint zone. The concrete damage plasticity model for concrete and ECC material under cyclic loading was proposed. Accordingly, the Finite Element Analysis (FEA) model was established with the consideration of different constitutive material models for concrete and Engineered Cementitious Composites. The accuracy of the proposed FEA model was validated with the experimental results. Failure mechanism, crack propagation, moment rotation relationship, and energy absorption under cyclic loading were investigated. Under controlled deformation, cyclic loads were applied to the samples at the end of the beam up to the failure point. It was found that the use of various grades of Engineered Cementitious Composites in the joint zone was effective in enhancing the ultimate moment capacity upto 38.50%, ductility upto 13.72%, and siffniness degradation upto 28.57% respectively of the joint up to the failure stage alongwith significant reduction in crack propagation.

Thermophotovoltaic energy conversion is a solid-state thermal-to-electric energy conversion technique which uses only infrared light i.e., heat. Its maximum achieved efficiency by proper bandgap energy selection and utilizing spectral control strategies is merely 30% which is currently still low to be used as a standalone device for energy harvesting. Recently, researchers used molten metal storage and concentrated solar power (CSP) as an input to derive these thermophotovoltaic blocks. Such blocks usually consist of an emitter and a photovoltaic power converter which boosted the system efficiency by adding a silver-based reflector to bounce unused photons back to the emitter. In this work, we have demonstrated another means of photon recycling on the conversion efficiency by passing the radiations through spectral filters before incident on these cells. The spectral filters were selected by aiming at gaining maximum conversion efficiency and a cylindrical power block was used in order to reduce the conversion losses due to edge effects. The modified model in terms of geometrical shape and spectrally controlled filters was able to achieve a conversion efficiency up to 50% even without using the back surface reflectors (BSRs). This work provides the framework for a cheap and efficient alternative to the combined-cycle electric turbines currently used to convert heat into energy inside utility-scale concentrated solar power facilities. This work enables widespread use wherever solar energy is available in abundance.

Compression ignition engines are one of the world’s largest consumers of fossil oil but have energy extraction efficiency limited to 35%. Addition of hydrogen alongside diesel fuel has been found to improve engine performance and efficiency; however, after a certain limit, hydrogen begins to show adverse effects, mainly because the ratio of oxygen to fuel decreases. This can be overcome by using oxyhydrogen, which is a mixture of hydrogen and oxygen gas.In this study, effects of addition of oxyhydrogen generated by electrolysis, with varying flows at the intake manifold, on a 315 cc compression ignition engine alongside diesel were analyzed.The engine was mounted on a Thepra test bed and torque measurements were taken at predetermined test points for diesel and 6 and 10 standard cubic feet per hour flowrates of oxyhydrogen.H10 showed the maximum improvement in engine performance equating to a 22.4% increase in both torque and power at 3000 r/min, and a 19.4% increase in efficiency at 2600 r/min was recorded. The large increase in engine performance as compared to previous results is because of high oxyhydrogen flowrate to displacement volume ratio.The oxyhydrogen flowrate to displacement ratio is the most important factor as it is directly impacts engine performance. The difference in engine performance because of oxyhydrogen becomes prominent at higher engine speed due to high suction pressure. No experimental flowrates of oxyhydrogen showed any adverse effect on the engine performance.

This research comprehensively investigates the effect of uncertain time delay on performance of the deadbeat control. A solution based on a non-integer order Smith predictor has been proposed and analyzed to compensate uncertain time delays occurring in a stable closed loop system. Deadbeat control has been widely and conveniently used in the control of linear and non-linear systems. However, this control technique is severely sensitive to unmodeled dynamics and parameter uncertainties. Thus the performance of system may deviate significantly and hence lead to instability in practical cases. Time delay in a closed loop control system is a common source of unmodeled dynamics, which severely deteriorates control accuracy and results in reduced stability margin of the deadbeat control system. Physical system considered in this research work is a single-phase inverter. The simulation results indicate that the Smith predictor based deadbeat control scheme offers accurate time delay compensations and thus enhances the robustness and stability margin. Application example comprehensively illustrates effectiveness of the proposed control technique.