Journal of Materials Science - The synthesis of metal modified polycarbosilanes is currently an area of significant activity. These polymers can be processed to advanced materials such as ceramic... 相似文献
Chalcopyrite thin films of CuIn0.75Al0.25Se2 have been grown by a two-stage process containing e-beam evaporation of a threefold (In/Cu/Al/Se) precursor deposition onto glass substrates in a high vacuum followed by post selenization at various temperatures (300–550 °C) using a horizontal tubular furnace. The X-ray diffraction pattern of precursor layers selenized at?≤?525 °C shows the formation of co-existence of CuInSe2 and Cu(In,Al)Se2 phases, as well as a mixture of two Cu(In,Al)Se2 phases with different Al content. The precursor layers selenized at 550 °C results in the formation of single-phase Cu(In,Al)Se2 thin films. The presence of an intense A1 mode at 174.7 cm?1 in the Raman spectra of selenized films at 550 °C confirms the growth of Cu(In,Al)Se2 phase. The energy-dispersive spectra of stacked layers selenized at 550 °C shows a Cu-poor and (In?+?Al)-rich composition with atomic ratios of Cu/(In?+?Al)?=?0.79, Al/(In?+?Al)?=?0.25, and Se/(Cu?+?In?+?Al)?=?0.98. The secondary ion mass spectra depth study reveals a shift in Al distribution from graded to uniform with an increase in selenization temperature to 550 °C. The stacked layers selenized at 550 °C reveal a uniform distribution of void-free dense grains (~?0.7 μm). Optical and electrical studies of selenized Cu(In,Al)Se2 films at 550 °C show a direct band gap of 1.22 eV with a higher hole mobility of 14.0 cm2/V-s. The heterojunction solar cell of p-Cu(In,Al)Se2/n-CuAlSe2 was numerically simulated using SCAPS-1D software, yielding a high power conversion efficiency (η) of 21.01%.
Wireless Sensor Network (WSN) with remote sensing capability is gaining popularity in many of the real time applications such as military, healthcare, environment, home and other commercial applications.WSN is typically composed of various components such as sensor node, relay node, cluster head, gateway, base station. Such a critical network is vulnerable to most dangerous threats caused by worms towards the integrity and confidentiality of information passed through it. The study of the influence of clamor in propagation of potential of worm in WSN is of more significance. In this paper, a logical model is proposed that is reliant on pandemic theory. It is an improvement of the SIRS, SEIS and models. We propose an altered SEIRS (Susceptible-Exposed-Infectious-Recovered-Susceptible) model with the added substance background noise that overcomes the drawbacks of the existing models. The close by adequacy of the model has been affirmed using Lyapunov’s work. We similarly address the effect of node fluctuations in the model through numerical simulations that is carried out to prove that our proposed system is mean square stable and resistance against fluctuations with respect to the spread of worms.
ABSTRACTEnergy assessment of a simple direct expansion solar-assisted heat pump system has been experimentally assessed with R433A as a possible alternative to R22. An artificial neural network integrated genetic algorithm model was developed to assess the performance system. The data obtained from the experimentation at different ambient conditions are used as the training data for the ANN network. The back propagation learning mechanism with variants Lavenberg-Maguardt with 20 neurons in the hidden layer were used in modelling of ANN. The values obtained from the analysis using ANN are optimised further by integrating the ANN procedure with GA. The results indicated that R433A has 6.4% and 1% lower instantaneous compressor power consumption and heating capacity compared to R22. Energy performance ratio of R433A was found to be about 5.67% higher compared to R22. The results confirmed that R433A can be used as a possible alternative to R22 DX-SAHP systems. 相似文献
The primary objective of any transit system is to provide a better level of service to its passengers. One of the good measures of level of service is the waiting time of passengers during their journey. The waiting time consists of an initial waiting time (the time a passenger waits to board a vehicle at his or her point of origin) and a transfer time (the time a passenger waits at a transfer station while transferring from one vehicle to another). An efficient schedule minimizes the overall transfer time (TT) of passengers transferring between different routes as well as the initial waiting time (IWT) of the passengers waiting to board the vehicle at their point of origin. This paper uses genetic algorithm (GA)—a search and optimization procedure—to find optimal/near-optimal schedules of vehicles in a transit network. The main advantage of using GA is that the transit network scheduling problem can be reformulated in a manner that is computationally more efficient than the original problem. Further, the coding aspect of GA inherently takes care of most of the constraints associated with the scheduling problem. Results from a number of test problems show that GAs are able to find optimal/near-optimal schedules with minimal computational resources. 相似文献
The fabrication of highly ordered, defect-free nanostructures is a key challenge in nanotechnology. Bottom-up fabrication approaches require nanobuilding blocks of precisely defined size and shape. In this work we propose a simple approach to obtain one type of building block--soft patchy nanoparticles--suggested by a series of coarse grain molecular dynamics simulations. A binary mixture of two different diblock copolymers with a common hydrophobic block but sufficiently dissimilar hydrophilic blocks reliably self-assembles into a "patchy" spherical micelle in water, with phase separation of the two hydrophilic blocks on the surface of the micelle core. Subsequent crosslinking of the core to solidify the patchy sphere geometry should allow further hierarchical assembly. Altering the hydrophilic versus hydrophobic composition of each polymer yields a change of morphology from "patchy spheres" to "patchy cylinders". Furthermore, by controlling the interaction strength of the blocks with solvent, the patches can be selectively placed either on the outer surface or inside the core of the micelle. The number and size of the patches are found to be largely controlled by the composition of the binary copolymer mixture. 相似文献
Two space-vector-based pulse-width-modulated (PWM) strategies are proposed for a dual two-level inverter-fed open-end winding induction motor drive. Neither of these PWM strategies require sector identification or lookup tables. These PWM strategies require only instantaneous phase reference voltages. Also, a simple model is suggested to compute the motor phase currents for this drive, and this model is validated through experimentation. The inverter losses are estimated for this drive system with these PWM strategies using an existing thermal model. The simulation studies suggest that one of these two PWM strategies is better than the other, as it causes lower losses in the inverters. 相似文献
Demand Response (DR) provides both operational and financial benefits to a variety of stakeholders in the power
system. For example, in the deregulated market operated by the Electric Reliability Council of Texas (ERCOT), load
serving entities (LSEs) usually purchase electricity from the wholesale market (either in day-ahead or real-time
market) and sign fixed retail price contracts with their end-consumers. Therefore, incentivizing end-consumers’ load
shift from peak to off-peak hours could benefit the LSE in terms of reducing its purchase of electricity under high
prices from the real-time market. As the first-of-its-kind implementation of Coupon Incentive-based Demand
Response (CIDR), the EnergyCoupon project provides end-consumers with dynamic time-of-use DR event
announcements, individualized load reduction targets with EnergyCoupons as the incentive for meeting these
targets, as well as periodic lotteries using these coupons as lottery tickets for winning dollar-value gifts. A number
of methodologies are developed for this special type of DR program including price/baseline prediction,
individualized target setting and a lottery mechanism. This paper summarizes the methodologies, design, critical
findings, as well as the potential generalization of such an experiment. Comparison of the EnergyCoupon with a
conventional Time-of-Use (TOU) price-based DR program is also conducted. Experimental results in the year 2017
show that by combining dynamic coupon offers with periodic lotteries, the effective cost for demand response
providers in EnergyCoupon can be substantially reduced, while achieving a similar level of demand reduction as
conventional DR programs. 相似文献