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排序方式: 共有118条查询结果,搜索用时 15 毫秒
51.
Mozaffari Saeed Javadi Saman Moghaddam Hamid Kardan Randhir Timothy O. 《Water Resources Management》2022,36(6):1955-1972
Water Resources Management - Forecasting the groundwater level is crucial to managing water resources supply sustainably. In this study, a simulation–optimization hybrid model was developed... 相似文献
52.
In this paper, the differential quadrature method (DQM) was employed to study nonlinear analysis of annular isotropic membrane
in which an attempt was made to explore the applicability and accuracy of DQM for nonlinear analysis of a structural membrane.
For this purpose, the large deformation analyses of symmetric circular membranes were investigated. Relaxed strain energy
function in conjunction with Green’s strain and perfectly flexible assumptions was utilized for modeling the nonlinear behavior
of the membranes. The nonlinear governing equations were discretized at whole domain grid points, and boundary conditions
were implemented exactly at boundary grid points. Comparative studies were made between approaches for different boundaries.
Convergence of the methodology was demonstrated, and the results were compared with existing solutions of other methods, such
as dynamic relaxation. It was shown that accurate results were obtained even when utilizing only a small number of grid points. 相似文献
53.
Omar Sami Oubbati Mohammad Mozaffari Noureddine Chaib Pascal Lorenz Mohammed Atiquzzaman Abbas Jamalipour 《International Journal of Communication Systems》2019,32(18)
Much progress can be expected in the domain of unmanned aerial vehicle (UAV) communication by the next decade. The cooperation between multiple UAVs in the air exchanging data among themselves can naturally form a flying ad hoc network (FANET). Such networks can be the key support to accomplish several kinds of missions while providing the required assistance to terrestrial networks. However, they are confronted with many challenges and difficulties, which are due to the high mobility of UAVs, the frequent packet losses, and the weak links between UAVs, all affecting the reliability of the data delivery. Furthermore, the unbalanced energy consumption may result in earlier UAV failure and consequently accelerate the decrease of the network lifetime, thus disrupting the overall network. This paper supports the use of the movement information and the residual energy level of each UAV to guarantee a high level of communication stability while predicting a sudden link breakage prior to its occurrence. A robust route discovery process is used to explore routing paths where the balanced energy consumption, the link breakage prediction, and the connectivity degree of the discovered paths are all considered. The performance of the scheme is evaluated through a series of simulations. The outcomes demonstrate the benefits of the proposed scheme in terms of increasing the lifetime of the network, minimizing the number of path failures, and decreasing the packet losses. 相似文献
54.
A pseudo‐kinetic model for the treatment of a distillery wastewater by the ultraviolet irradiation and hydrogen peroxide process in a continuous tubular photoreactor is developed. There is a scarcity of information on modelling of organic degradation rates based on chemical oxygen demand (COD) and total organic carbon (TOC) in advanced oxidation technologies (AOTs). In this study, the COD and TOC are used as surrogate parameters to design a photoreactor instead of individual concentrations of species. The rate constants for the reaction between COD and TOC with hydroxyl radicals were determined to be 4.9 × 109 and 5.0 × 106 M?1 s?1, respectively. A laminar flow model was simulated to estimate the velocity and residence time of the medium in a cylindrical photoreactor. The model was validated by the experimental data published in the open literature for different concentrations of H2O2 (1, 10, and 100 mM), COD (589, 709, and 850 mg O2 L?1), and TOC (190, 200, and 192 mg C L?1). The optimal value of the inlet hydrogen peroxide concentration was predicted to be 400 mg L?1. Axial and radial concentration distributions of species in the photoreactor were also obtained. At different photoreactor radii (from 50 to 200 mm), the values of radial local volumetric rate of energy absorption (LVREA) were estimated. It was found that a higher LVREA was achieved in the photoreactor space at smaller radii. © 2011 Canadian Society for Chemical Engineering 相似文献
55.
Samaneh Mozaffari Mohammad Reza Nateghi Abbas Behjat Mahmood Borhani-Zarandi 《Iranian Polymer Journal》2012,21(11):799-808
Schottky-barrier diode devices were fabricated in a sandwich configuration with poly(pyrrole-co-indole) copolymer semiconducting films prepared by electropolymerization. Effect of different dopants of ClO4 ?, BF4 ?, C7H7SO3 ? and [Fe(CN)6]3? on the electronic properties of the fabricated devices was followed using Ag, In, Al and Cu metal junctions. Current?Cvoltage and capacitance?Cvoltage characteristics were recorded for making a comparative evaluation of the electronic and junction properties of the devices. The electrical characteristics of the junctions were analyzed based on the standard thermionic emission theory. Polymer doped by ClO4 ? showed lower reverse saturation currents and ideality factor but higher potential barriers and rectification ratios. Effect of dopant ions and copolymerization on the optical band gaps (E g) of the films were investigated and the optical transmissions of the doped copolymer films were measured in the wavelength range of 250?C900?nm. It was shown that the energy gap of copolymers laid between those of corresponding homopolymers and polyindole (PIN) doped by [Fe(CN6)]?3 had E g less than that of polymer doped by other anions whereas E g of polypyrrole was independent of dopant ions. Also, the morphology of the polymeric films revealed the surface of the PIN doped with ClO4 ? was very smooth which created a good contact with indium metal. 相似文献
56.
Multilayered Al/Ni composites were produced by accumulative roll bonding (ARB) process using Al 1060 and commercial Ni foils. In this process it was observed that nickel layers necked and fractured as accumulative roll bonding passes increased. After six ARB passes, a multilayered Al/Ni composite with homogeneously distributed fragmented nickel layers in aluminum matrix was produced. Structure and mechanical properties of these multilayer composites were evaluated at different passes of ARB process. During ARB, it was observed that as the strain increased with the number of passes, the strength, microhardness and elongation of produced composites increased as well. In addition, enhancement of the strength was shown to be higher than the tensile strength of Al/Al and Al/Cu multilayered composites produced by ARB process in the previous works by the same authors. 相似文献
57.
Joint Compensation of Transmitter and Receiver IQ Imbalance in OFDM Systems Based on Selective Coefficient Updating 下载免费PDF全文
In this paper, a selective coefficient updating (SCU) approach at each branch of the per‐tone equalization (PTEQ) structure has been applied for insufficient cyclic prefix (CP) length. Because of the high number of adaptive filters and their complex adaption process in the PTEQ structure, SCU has been proposed. Using this method leads to a reduction in the computational complexity, while the performance remains almost unchanged. Moreover, the use of set‐membership filtering with variable step size is proposed for a sufficient CP case to increase convergence speed and decrease the average number of calculations. Simulation results show that despite the aforementioned algorithms having similar performance in comparison with conventional algorithms, they are able to reduce the number of calculations necessary. In addition, compensation of both the channel effect and the transmitter/receiver in‐phase/quadrature‐phase imbalances are achievable by these algorithms. 相似文献
58.
Shideh Fathi Roudsari Ramdhane Dhib Farhad Ein‐Mozaffari 《Polymer Engineering and Science》2015,55(4):945-956
The emulsion polymerization of methyl methacrylate (MMA) was carried out in a lab‐scale reactor, which was equipped with a pitched blade turbine, four baffles, a U shaped cooling coil, and a temperature controller. Potassium persulfate was used as the initiator and sodium dodecyl sulfate as the surfactant. The effects of impeller speed, mounting baffles, and reaction temperature on the monomer conversion, polymer nano particle size and number, and molecular weight were examined in detail. An increase in the impeller speed up to 250 rpm enhanced the polymer properties but further agitation reduced the conversion, particle size, and molecular weight. The installation of the baffles enhanced the particle size and molecular weight but reduced the conversion and particle number. The use of baffles resulted in a narrower size distribution throughout the polymerization process. While the particle size and molecular weight were reduced with an increase in the reaction temperature, the monomer conversion and particle number were improved. POLYM. ENG. SCI., 55:945–956, 2015. © 2014 Society of Plastics Engineers 相似文献
59.
60.
The main scope of the current study is to develop a systematic stochastic model to capture the undesired uncertainty and random noises on the key parameters affecting the catalyst temperature over the coldstart operation of automotive engine systems. In the recent years, a number of articles have been published which aim at the modeling and analysis of automotive engines’ behavior during coldstart operations by using regression modeling methods. Regarding highly nonlinear and uncertain nature of the coldstart operation, calibration of the engine system’s variables, for instance the catalyst temperature, is deemed to be an intricate task, and it is unlikely to develop an exact physics-based nonlinear model. This encourages automotive engineers to take advantage of knowledge-based modeling tools and regression approaches. However, there exist rare reports which propose an efficient tool for coping with the uncertainty associated with the collected database. Here, the authors introduce a random noise to experimentally derived data and simulate an uncertain database as a representative of the engine system’s behavior over coldstart operations. Then, by using a Gaussian process regression machine (GPRM), a reliable model is used for the sake of analysis of the engine’s behavior. The simulation results attest the efficacy of GPRM for the considered case study. The research outcomes confirm that it is possible to develop a practical calibration tool which can be reliably used for modeling the catalyst temperature. 相似文献