Phosphorene-AsP Heterostructure as a Potential Excitonic Solar Cell Material - A First Principles Study

Solar energy conversion to produce electricity using photovoltaics is an emerging area in alternative energy research. Herein, we report on the basis of density functional calculations, phosphorene/AsP heterostructure could be a promising material for excitonic solar cells (XSCs). Our HSE06 functional calculations show that the band gap of both phosphorene and AsP fall exactly into the optimum value range according to XSCs requirement. The calculated effective mass of electrons and holes show anisotropic in nature with effective masses along ${\Gamma}$-X direction is lower than the ${\Gamma}$-Y direction and hence the charge transport will be faster along ${\Gamma}$-X direction. The wide energy range of light absorption confirms the potential use of these materials for solar cell applications. Interestingly, phosphorene and AsP monolayer forms a type-II band alignment which will enhance the separation of photogenerated charge carriers and hence the recombination rate will be lower which can further improve its photo-conversion efficiency if one use it in XSCs

Examining the resilience of UAE to decline in oil prices - the case of the insurance sector

The sharp fall in oil prices from $112/barrel in 2014 to$59/barrel in 2019 impacted many economies in the world in both positive and negative manner. United Arab Emirates (UAE) has been seeking diversification to reduce its reliance on oil revenues and expects higher growth from non-oil revenues in 2020. This study aims to examine the resilience of UAE to decline in oil prices with the insurance sector as a representative sector of the economy This study involves calculations and comparisons of financial ratios pre- and post-fall in oil prices in the UAE. Parametric test results indicate that while the change in investment and efficiency ratios is statistically significant, profitability, efficiency and gearing ratios have been quite stable in the period. Despite the overall slowdown in the insurance industry, the sector has been mostly resistant to the drop in oil prices. This resilience can be attributed to the ongoing efforts of UAE leadership to diversify away from an oil-based economy

Measuring Environmental Efficiency of Industry: A Case Study of Thermal Power Generation in India

Technical and environmental efficiency of some coal-fired thermal power plants in India is estimated using a methodology that accounts for firm’s efforts to increase the production of good output and reduce pollution with the given resources and technology. The methodology used is directional output distance function. Estimates of firm-specific shadow prices of pollutants (bad outputs), and elasticity of substitution between good and bad outputs are also obtained. The technical and environmental inefficiency of a representative firm is estimated as 0.10 implying that the thermal power generating industry in Andhra Pradesh state of India could increase production of electricity by 10 per cent while decreasing generation of pollution by 10 percent. This result shows that there are incentives or win-win opportunities for the firms to voluntarily comply with the environmental regulation. It is found that there is a significant variation in marginal cost of pollution abatement or shadow prices of bad outputs across the firms and an increasing marginal cost of pollution abatement with respect to pollution reduction by the firms. The variation in marginal cost of pollution abatement and compliance to regulation across firms could be reduced by having economic instruments like emission tax.environmental and technical efficiency; shadow prices of bad outputs; air pollution

Phase control of electromagnetically induced transparency and its applications to tunable group velocity and atom localization

We show that, by simple modifications of the usual three-level $\Lambda$-type scheme used for obtaining electromagnetically induced transparency (EIT), phase dependence in the response of the atomic medium to a weak probe field can be introduced. This gives rise to phase dependent susceptibility. By properly controlling phase and amplitudes of the drive fields we obtain variety of interesting effects. On one hand we obtain phase control of the group velocity of a probe field passing through medium to the extent that continuous tuning of the group velocity from subluminal to superluminal and back is possible. While on the other hand, by choosing one of the drive fields to be a standing wave field inside a cavity, we obtain sub-wavelength localization of moving atoms passing through the cavity field.Comment: To Appear in SPIE Proceedings Volume 573

Target Handing over System using Pyramid Processing .

The image seen by the low resolution (LR) sensor and the image (of the same scene) seen by the operator through the high resolution (HR) sensor are different in spatial resolution. To establish the correlation between these two images, the HR image needs to be resampled and made similar to the LR sensor image by applying a pre-processing technique. The pre-processing will be carried out by handing over system that resamples the HR sensor image making it compatible with LR sensor image and hands over the resampled image to the LR sensor through a serial link. The pre-processing technique reported by Boland has been studied, analysed and implemented using 86 family of processors. Automatic target handing over system discusses the implementation of pre-processing technique, computational complexity and criticality of the execution time. The execution time reported was 1.5 s, whereas the requirement is of the order of few milliseconds for the typical set of conditions. This paper discusses the implementation of a suitable handing over algorithm. Emphasis has been to develop hardware and software to reduce the execution time, which has been brought down from 1.5 s to 40 ms for a typical set of conditions. Emphasis has also been given to reduce the transmission time by applying suitable pyramid processing techniques. The hardware is designed around i486 processor, and the software is developed in PL/M86

Vector modes generated by primordial density fluctuations

While vector modes are usually ignored in cosmology since they are not produced during inflation they are inevitably produced from the interaction of density fluctuations of differing wavelengths. This effect may be calculated via a second-order perturbative expansion. We investigate this effect during the radiation era. We discuss the generation mechanism by investigating two scalar modes interacting, and we calculate the power of vector modes generated by a power-law spectrum of density perturbations on all scales.Comment: 10 pages, 2 figures, minor changes in main text and new appendix added to match the accepted version for Physical Review D publicatio

Automatic Target Handing Over System .

The image seen by the airborne seeker and the image (of the same scene) seen by the operator through the high resolution sensor (thermal sight) are different in spatial resolution. In order to establish the correlation between these two images, the thermal sight image needs to be resampled and made similar to the seeker image by applying a preprocessing technique. The preprocessing is carried out by a handling over system (HOS) that resamples the thermal sight image making it compatible with seeker image and hands over the resampled image to the seeker. This paper discusses the implementation of the suitable handling over algorithm. (Boland, J.S. et al. automatic target hand using correlation techniques. Technical report, Auburn University, Alabama, 31 January, 1977, pp.57-63). Emphasis is laid on developing suitable hardware and software and tests to match the two images obtained by two different sensors of the same scene. The hardware and software have been evaluated with sets of images. The H/W is designed around iAPX 86 family of processor and software is developed in PL/M. Hardware also includes the recording facility on a standard VCR, to record the performance of handling over electronics (HOE) during testing/flight trials. Evaluation of the system by realistically simulating the field scenario in the laboratory has shown that the HOS is functioning satisfactorily

Generation of Werner states via collective decay of coherently driven atoms

We show deterministic generation of Werner states as a steady state of the collective decay dynamics of a pair of neutral atom coupled to a leaky cavity and strong coherent drive. We also show how the scheme can be extended to generate $2N$-particle analogue of the bipartite Werner states.Comment: 4 pages, 1 figur