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31.
Rita Chaddha Deepti Lehri Rajesh Mohan Feroz Ahmed 《Journal of Materials Science》1992,27(23):6316-6320
The results of a theoretical simulation of a transient experiment in n-InSb in the temperature range 77–300 K, are reported. Minority carrier lifetimes for the three recombination processes, radiative, SRH and Auger, have been calculated at different temperatures using the temperature dependence of intrinsic carrier concentration,n
i
, and density of states effective mass of heavy holes,m
d. It was found that around room temperature the lifetimes for the three processes become comparable and at higher temperatures the Auger lifetime becomes dominant. This fact was ignored in previous work where only SRH and radiative processes were considered in the calculation of effective lifetime. The present results of effective lifetime in n-InSb are in reasonably good agreement with the results obtained previously. The effect of higher time modes on the decay of photoresponse to pulsed radiation is discussed. An instantaneous time constant has been defined and its variation with time at different temperatures has been studied.On leave from Atma Ram Sanatan Dharma College, University of Delhi, New Delhi 110021, India. 相似文献
32.
Arvind Bharti 《Bulletin of Materials Science》1988,11(2-3):191-212
A brief state-of-the-art review of laser welding has been presented. Results of our experimental studies on laser welding
of Ti-6Al-4V have been reported. Results of weld evaluation including microstructure, mechanical properties and microchemistry
have also been presented. 相似文献
33.
A new, short, and quick method was developed for preparation of specimen for observing Actinomycetes of genus Streptomyces by scanning electron microscopy. The cultures were directly grown on stubs and coated with a film of gold without using any fixative and dehydrating procedures. Using this simple preparation procedure, surface of intact sporing structures of Streptomyces was observed over a range of magnifications. As the preparation procedure is so simple and rapid, this procedure could be most useful for the routine examination and identification of Streptomyces. 相似文献
34.
Santosh Kumar Bharti Sharma Awadhesh Kumar Singh 《International Journal of Communication Systems》2020,33(8)
Numerous research articles exist for backbone formation in wireless networks; however, they cannot be applied straightforward in cognitive radio network (CRN) due to its peculiar characteristics. Since virtual backbone has many advantages such as reduced routing overhead, dynamic maintenance, and fast convergence speed, we intend to propose a backbone formation protocol in CRN. In this paper, we propose a tree‐based backbone formation protocol along with its maintenance. Our protocol is based on non‐iterative approach, thus leading towards limited message overhead and faster convergence speed. The proposed algorithm first forms the tree by maintaining the parent‐child relationship, and second, the parent nodes are connected together to form the virtual backbone. In the end, we evaluate the performance our protocol through extensive simulations. 相似文献
35.
Ishani Khurana Ajay Kumar Shaw Bharti Jitender M. Khurana 《Fullerenes, Nanotubes and Carbon Nanostructures》2020,28(7):571-581
Abstract2,4,6-Trinitrophenol (TNP), an explosive utilized for artillery munitions, ends up polluting water and soil. This study targets the treatment of TNP contaminated water via adsorption technique. A comparative adsorption study using pristine rGO (reduced graphene oxide), α-Fe2O3/rGO, bare α-Fe2O3 and physical mixture of α-Fe2O3 & rGO has been carried to select the most suitable adsorbent. To understand the mechanism of adsorption of TNP on α-Fe2O3/rGO adsorption isotherms were applied on adsorption data. The adsorption kinetics followed pseudo second order kinetic model. The mechanism of adsorption changed significantly with change in pH. The maximum adsorption capacity was found to be 769.23?mg?·?g?1. Regeneration studies indicated that the adsorbent can be used up to 3 times without significant decrease in adsorption efficiency. Magnetic nature of adsorbent allowed its easy segregation from the contaminant solution upon application of external magnetic field. To assess the adsorption efficacy of α-Fe2O3/rGO in real water under ambient condition, TNP was spiked in ground water samples collected from adjoining district that had high TDS (Total dissolved solids). The Langmuir adsorption capacity of 164.24?mg?·?g?1 was attained with substantial decrease in TDS. Thus α-Fe2O3/rGO proves to be an efficient adsorbent for nitrophenols and can be used commercially for waste water treatment. 相似文献
36.
Kinetic and thermodynamic studies were conducted with the natural dye lawsone (2-hydroxy-1, 4-naphthoquinone) on six substrates at various temperatures. All the substrates showed high dye uptake and were dyed to deep shades. The adsorption isotherms, rate of dye uptake, diffusion coefficients, standard affinity, enthalpy and heat of dyeing have been calculated and discussed. 相似文献
37.
Deepankar Choudhury Rajeev Kumar Bharti Siddharth Chauhan Buddhima Indraratna 《Canadian Metallurgical Quarterly》2008,134(10):1558-1563
For an efficient and economical design of a railway track system, it is necessary to understand the behavior of each track component with special reference to ballast and subgrade, which play a pivotal role in distributing the large, cyclic wheel loads longitudinally, laterally, and vertically away from the wheel contact area on the rail surface to the underlying soil strata. This paper presents an analytical model of a track-ballast-subgrade system with different formation soils such as dense uniform sand, stiff clay, loose sand, and soft clay modeled by using a mass-spring dashpot system with two degrees of freedom. This represents the varying energy distribution through ballast and subgrade in the vertical direction. Results are presented in the form of time-displacement response profiles for both the ballast and subgrade layers. In addition, the magnification factors for displacements with variation in subgrade soils for cyclic loading frequencies are reported. It is observed that the results obtained from the present analysis follow the experimentally observed trends already available in the literature. 相似文献
38.
In order to meet the growing demand for mobile multimedia broadcast services 3GPP includes evolved multimedia broadcast and multicast (eMBMS) services in LTE systems. The high data rates, low latency and QoS provisioning makes LTE systems more suitable for mobile broadcast and multicast services than legacy wireless networks. However, the 3GPP standards has not specified any scheduling strategy for this broadcast and multicast services. In this paper, we propose a novel eMBMS scheduling technique (NEST) which focuses on reducing the average waiting time (latency) of the broadcast services offered by LTE system. This paper has twofold contributions. We proffer NEST considering two types of impatience that is user equipment (UE) departure and UE request repetition. Our proposed scheduling strategy estimates the effects originating from the departure of the mobile UEs and UE request repetition case. It intelligently combines the advantages of both flat scheduling and on-demand scheduling in such a way that the overall latency of the system is reduced. We design a suitable modeling framework to analyze the performance of the system. Simulation experiments on typical LTE systems support the performance analysis and demonstrates 10 % gains while comparing with existing eMBMS scheduling available in present LTE systems. 相似文献
39.
The low elastic modulus and the ability to withstand high strain without failure make the conducting polymer attractive for a wide range of acoustic applications based on high‐strain electroactive polymers. In this article, we examine the electric and electromechanical performance of all‐polymer electromechanical systems, fabricated by painting conductive polyaniline (PANI) doped with camphor sulfonic acid (HCSA) on both sides of electrostrictive Poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)) copolymer films, and compare them with those from the same copolymers with gold electrodes. The all‐polymer composite films are flexible, with strong coherent interfaces between the electrostrictive polymer layer and the conductive polymer layer. The electric performance such as dielectric properties and polarization hysteresis loops from P(VDF‐TrFE)/PANI film is nearly identical to those of P(VDF‐TrFE)/gold films in a wide temperature (from −50 to 120°C), and frequency range (from 1 Hz to 1 MHz). The all‐polymer systems also show a similar or even larger electric field induced strain response than that of films with electrodes under identical measurement conditions. The results demonstrate that the polyaniline/HCSA is good candidate material as the electrodes for electroactive polymers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 945–951, 2000 相似文献