Inverse coefficient problem for cascade system of fourth and second order partial differential equations

The study of the paper mainly focusses on recovering the dissipative parameter in a cascade system coupling a bilaplacian operator to a heat equation from final time measured data via quasi-solution based optimization. The coefficient inverse problem is expressed as a minimization problem. We proved that minimizer exists and the necessary optimality condition which plays the crucial role to prove the required stability result for the corresponding coefficient is derived. Utilising the conjugate gradient approach, numerical results are examined to show the method's effectiveness.Comment: 24 pages, 18 figure

Simulation of a Diesel Engine with Variable Geometry Turbocharger and Parametric Study of Variable Vane Position on Engine Performance

Modelling of a turbocharger is of interest to the engine designer as the work developed by the turbine can be used to drive a compressor coupled to it. This positively influences charge air density and engine power to weight ratio. Variable geometry turbocharger (VGT) additionally has a controllable nozzle ring which is normally electro-pneumatically actuated. This additional degree of freedom offers efficient matching of the effective turbine area for a wide range of engine mass flow rates. Closing of the nozzle ring (vanes tangential to rotor) result in more turbine work and deliver higher boost pressure but it also increases the back pressure on the engine induced by reduced turbine effective area. This adversely affects the net engine torque as the pumping work required increases. Hence, the optimum vane position for a given engine operating point is to be found through simulations or experimentation. A thermodynamic simulation model of a 2.2l 4 cylinder diesel engine was developed for investigation of different control strategies. Model features map based performance prediction of the VGT. Performance of the engine was simulated for steady state operation and validated with experimentation. The results of the parametric study of VGT’s vane position on the engine performance are discussed

Development and Demonstration of Control Strategies for a Common Rail Direct Injection Armoured Fighting Vehicle Engine

The development of a controller which can be used for engines used in armoured fighting vehicles is discussed. This involved choosing a state of the art reference common rail automotive Diesel engine and setting-up of a transient engine testing facility. The dynamometer through special real-time software was controlled to vary the engine speed and throttle position. The reference engine was first tested with its stock ECU and its bounds of operation were identified. Several software modules were developed in-house in stages and evaluated on special test benches before being integrated and tested on the reference engine. Complete engine control software was thus developed in Simulink and flashed on to an open engine controller which was then interfaced with the engine. The developed control software includes strategies for closed loop control of fuel rail pressure, boost pressure, idle speed, coolant temperature based engine de-rating, control of fuel injection timing, duration and number of injections per cycle based on engine speed and driver input. The developed control algorithms also facilitated online calibration of engine maps and manual over-ride and control of engine parameters whenever required. The software was further tuned under transient conditions on the actual engine for close control of various parameters including rail pressure, idling speed and boost pressure. Finally, the developed control strategies were successfully demonstrated and validated on the reference engine being loaded on customised transient cycles on the transient engine testing facility with inputs based on military driving conditions. The developed controller can be scaled up for armoured fighting vehicle engines

Association between internalized stigma and depression among HIV-positive persons entering into care in Southern India

Background: In India, which has the third largest HIV epidemic in the world, depression and HIV–related stigma may contribute to high rates of poor HIV–related outcomes such as loss to care and lack of virologic suppression. Methods: We analyzed data from a large HIV treatment center in southern India to estimate the burden of depressive symptoms and internalized stigma among Indian people living with HIV (PLHIV) entering into HIV care and to test the hypothesis that probable depression was associated with internalized stigma. We fitted modified Poisson regression models, adjusted for sociodemographic variables, with probable depression (PHQ–9 score ≥10 or recent suicidal thoughts) as the outcome variable and the Internalized AIDS–Related Stigma Scale (IARSS) score as the explanatory variable. Findings: 521 persons (304 men and 217 women) entering into HIV care between January 2015 and May 2016 were included in the analyses. The prevalence of probable depression was 10% and the mean IARSS score was 2.4 (out of 6), with 82% of participants endorsing at least one item on the IARSS. There was a nearly two times higher risk of probable depression for every additional point on the IARSS score (Adjusted Risk Ratio: 1.83; 95% confidence interval, 1.56–2.14). Conclusions: Depression and internalized stigma are highly correlated among PLHIV entering into HIV care in southern India and may provide targets for policymakers seeking to improve HIV–related outcomes in India

Arsenic (As) Removal Using Talaromyces sp. KM-31 Isolated from As-Contaminated Mine Soil

Bioremediation is an environmentally-benign and cost-effective approach to removing arsenic from contaminated areas. A fungal strain hyper-tolerant to arsenic was isolated from soil from a mine site and used for the removal of arsenic. The isolated fungus was identified as Talaromyces sp., and its growth rate, arsenic tolerance, and removal rates were investigated for As(III) and As(V). Arsenic tolerance tests revealed that the fungus was highly resistant to arsenic, tolerating concentrations up to 1000 mg/L. Robust mycelial growth was observed in potato dextrose broth containing either As(III) or As(V), and there was no difference in growth between that in arsenic-free medium and medium amended with up to 300 mg/L of either arsenic species. The isolate showed relatively low growth rates at As(V) concentrations >500 mg/L, and almost no growth at As(III) concentrations >300 mg/L. Both arsenic species were effectively removed from aqueous medium (>70%) in tests of the biosorption of arsenic onto mycelial biomass. Surface modification of the biomass with Fe(III) (hydr)oxides significantly enhanced arsenic removal efficiency. The findings indicate that this soil fungal strain has promise for use in bioremediation strategies to remove arsenic from highly contaminated aqueous systems

Remediation of Trichloroethylene by FeS-Coated Iron Nanoparticles in Simulated and Real Groundwater: Effects of Water Chemistry

The reactivity of FeS-coated iron nanoparticles (nFe/FeS) toward trichloroethylene (TCE) reduction was examined in both synthetic and real groundwater matrices to evaluate the potential performance of nFe/FeS in field treatment. The rate of TCE reduction increased with increasing pH, which is consistent with the pH effect reported previously for iron sulfide systems, but opposite that has been observed for (nonsulfidic) Fe⁰ systems. The rates of TCE reduction were unaffected by ionic strength over the range of 0.1–10 mM NaCl, increased with Ca²⁺ or Mg²⁺ concentrations, and inhibited by the presence of humic acid. The inhibitory effect of humic acid on the reactivity of nFe/FeS was largely alleviated when humic acid was combined with Ca²⁺/Mg²⁺, presumably due to decreased adsorption of humic acid onto nFe/FeS surface by the formation of humic acid–Ca²⁺/Mg²⁺ complexes