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排序方式: 共有311条查询结果,搜索用时 15 毫秒
41.
Ammar Abdulkadhim Azher M. Abed Hameed K. Hamzah Isam Mejbel Abed Nejla Said Mahjoub Farooq H. Ali 《亚洲传热研究》2024,53(4):1989-2009
The present investigation is on examination of the natural convection and entropy generation considering the heatlines visualization of nanofluid I-shaped enclosure with two corrugated walls considering inner rectangular heater of three different heights. The influence of Brownian motion along with thermophoresis had been implemented using Inhomogeneous two-phase model of nanofluid. The governing equations were solved numerically using COMSOL software. Influence of Rayleigh number , Buoyancy ratio number , Lewis number , heater length . The results indicate that the influence of Lewis number on heat transfer bettering is stronger at high Rayleigh number while its impact is negligible at a lower value of Rayleigh number (conduction mode). In addition, the total entropy generation gets its highest value at Lewis number . Bejan number, fluid flow strength and heat rate increase as the rectangular heater height increases. Also, higher heat transfer augmentation is taken when the heater height is while increasing the heater height to leads to more total entropy generation. The impact of heater height on total entropy generation is highly affected by Rayleigh number as increasing the heater height from into , total entropy generation increases by at while it increases by at . 相似文献
42.
43.
Mahgoub F. M. Hefnawy A. Hameed E. 《Protection of Metals and Physical Chemistry of Surfaces》2020,56(2):450-458
Protection of Metals and Physical Chemistry of Surfaces - Salix leaves water extract was studied for the corrosion inhibition of mild steel in H2SO4 at different temperatures. Energy dispersive... 相似文献
44.
Monitoring of Overhead Transmission Lines: A Review from the Perspective of Contactless Technologies
Arsalan Habib Khawaja Qi Huang Zeashan Hameed Khan 《Sensing and Imaging: An International Journal》2017,18(1):24
This paper describes a comprehensive review of non-contact technologies for overhead power transmission lines. Due to ever increasing emphasis on reducing accidents and speeding up diagnosis for automatically controlled grids, real time remote sensing and actuation is the new horizon for smart grid implementation. The technology overview with emphasis on the practical implementation of advanced non-contact technologies is discussed in this paper while considering optimization of the high voltage transmission lines parameters. In case of fault, the voltage and the current exceed limits of operation and hence real time reporting for control and diagnosis is a critical requirement. This paper aims to form a strong foundation for control and diagnosis of future power distribution systems so that a practitioner or researcher can make choices for a workable solution in smart grid implementation based on non-contact sensing. 相似文献
45.
The phenomena of natural convection caused by a concentration gradient usually creates currents as a result of buoyancy forces. These forces are formed from the combined effect of a fluid density gradient and the body force (gravitational force). The above phenomenon was studied experimentally in a circular glass column of 0.08 m diameter and 1 m length. This column was erected vertically and filled with distilled water with a salt bag placed on top of it and partially immersed in water. The dissolution mechanism was then modelled and a finite difference method was used to solve the formulated equations by using the implicit scheme of MacCormack (Anderson et al., 1984). The experimental results and the numerical predictions are represented graphically and give compatible agreement. 相似文献
46.
Zhaoguang Hu Quan Wen Jianhui Wang Xiandong Tan Hameed Nezhad Baoguo Shan Xinyang Han 《Energy Policy》2010
Many governments around the world are focusing on emissions reduction through energy efficiency improvements, particularly on the demand side. Although Integrated Resource Planning (IRP), which considers both supply-side and demand-side options, had been a useful tool in the planning process for the power industry, its effectiveness has been challenged recently with the restructuring of the power sector that has occurred in China and elsewhere around the world. The paper proposes Integrated Resource Strategic Planning (IRSP) as an alternative to IRP in a deregulated power sector. IRSP takes the resource planning process one step further to the national level. In this paper, the authors demonstrate the tremendous potential for efficiency improvements on both the supply and demand sides of the power sector in China with IRSP. The results show that between 2009 and 2020, the potential for electricity savings will reach about 1228.5 TWh, and the potential reduction in carbon dioxide (CO2) emissions will be about 1020.5 million tons. Another important finding of this study is that the current market-based pricing system in China should be improved to provide sufficient incentives for pursuing energy savings on the demand side. 相似文献
47.
Nickel oxide nanoparticles were formed on mesoporous carbon (NiO/MC) through precipitating nickel hydroxide species followed by post annealing treatment. The as-prepared electrocatalysts were physically characterized using XRD, Raman, EDX, SEM, TEM and HRTEM analysis techniques. Very fine nanoparticles were shown in TEM image and their chemical identity was proved in XRD pattern by three crystal indices of nickel oxide species as (111), (200) and (220). The electrocatalytic activity of NiO/MC electrocatalysts was investigated for oxidizing urea molecules in 0.5 M NaOH solution. Adding variable nickel oxide loading values during the electrocatalyst preparation method appreciably affected the obtained oxidation current density. Increasing the deposited oxide weight percentage would enhance the activity of formed nanocomposite to attain its optimum performance at the electrocatalyst containing 17.5 wt% NiO. The effect of altering urea concentration and scan rate during the oxidation process on the resultant electrocatalyst activity was studied. Chronoamperograms displayed improved steady state oxidation current density values after 1800 s revealing stable nanocatalysts. This promising electrocatalytic behavior of NiO/MC elects its application as an active component for urea electro-oxidation in many potential applications including hydrogen production, fuel cells and water purification. 相似文献
48.
Haris Hameed Mian Gang Wang Uzair Ahmed Dar Weihong Zhang 《Applied Composite Materials》2013,20(5):873-889
The use of composite pressure vessels particularly in the aerospace industry is escalating rapidly because of their superiority in directional strength and colossal weight advantage. The present work elucidates the procedure to optimize the lay-up for composite pressure vessel using finite element analysis and calculate the relative weight saving compared with the reference metallic pressure vessel. The determination of proper fiber orientation and laminate thickness is very important to decrease manufacturing difficulties and increase structural efficiency. In the present work different lay-up sequences for laminates including, cross-ply [0 m /90 n ] s , angle-ply [±θ] ns , [90/±θ] ns and [0/±θ] ns , are analyzed. The lay-up sequence, orientation and laminate thickness (number of layers) are optimized for three candidate composite materials S-glass/epoxy, Kevlar/epoxy and Carbon/epoxy. Finite element analysis of composite pressure vessel is performed by using commercial finite element code ANSYS and utilizing the capabilities of ANSYS Parametric Design Language and Design Optimization module to automate the process of optimization. For verification, a code is developed in MATLAB based on classical lamination theory; incorporating Tsai–Wu failure criterion for first-ply failure (FPF). The results of the MATLAB code shows its effectiveness in theoretical prediction of first-ply failure strengths of laminated composite pressure vessels and close agreement with the FEA results. The optimization results shows that for all the composite material systems considered, the angle-ply [±θ] ns is the optimum lay-up. For given fixed ply thickness the total thickness of laminate is obtained resulting in factor of safety slightly higher than two. Both Carbon/epoxy and Kevlar/Epoxy resulted in approximately same laminate thickness and considerable percentage of weight saving, but S-glass/epoxy resulted in weight increment. 相似文献
49.
R. MurawskiAuthor Vitae E. FelembanAuthor Vitae E. EkiciAuthor VitaeJ. ParkAuthor Vitae Z. Hameed MirAuthor Vitae 《Ad hoc Networks》2012,10(1):1-18
Directional antennas offer many potential advantages for wireless networks such as increased network capacity, extended transmission range and reduced energy consumption. Exploiting these advantages requires new protocols and mechanisms at various communication layers to intelligently control the directional antenna system. With directional antennas, many trivial mechanisms, such as neighbor discovery, become challenging since communicating parties must agree on where and when to point their directional beams to communicate.In this paper, we propose a fully directional neighbor discovery protocol called Sectored-Antenna Neighbor Discovery (SAND) protocol. SAND is designed for sectored-antennas, a low-cost and simple realization of directional antennas, that utilize multiple limited beamwidth antennas. Unlike many proposed directional neighbor discovery protocols, SAND depends neither on omnidirectional antennas nor on time synchronization. SAND performs neighbor discovery in a serialized fashion allowing individual nodes to discover all potential neighbors within a predetermined time. SAND guarantees the discovery of the best sector combination at both ends of a link, resulting in more robust and higher quality links between nodes. Finally, SAND reliably gathers the neighborhood information in a centralized location, if needed, to be used by centralized networking protocols. The effectiveness of SAND has been assessed via simulation studies and real hardware implementation. 相似文献
50.
Rashid Hameed Alain Sellier Anaclet Turatsinze Fr��d��ric Duprat 《International Journal of Mechanics and Materials in Design》2011,7(1):83-97
This contribution presents an effective and practical three dimensional (3D) numerical model to predict the behaviour of concrete
matrix reinforced with sliding metallic fibers. Considering fiber-reinforced concrete (FRC) as two-phase composite, constitutive
behaviour laws of plain concrete and sliding metallic fibers were described first and then they were combined according to
anisotropic damage theory to predict the mechanical behaviour of FRC. The behaviour law used for the plain concrete is based
on damage and plasticity theories able to manage localized crack opening in 3D. The constitutive law of the action of sliding
metallic fibers in the matrix is based on the effective stress carried by the fibers. This effective stress depends on a damage
parameter related to on one hand, on the content and mechanical properties of fibers and on the other hand, on the fiber–matrix
bond which itself depends on the localized crack opening. The proposed model for FRC is easy to implement in most of the finite
element codes based on displacement formulation; it uses only measurable parameters like Young’s modulus, tensile and compressive
strengths, fracture energies and strains at peak stress in tension and compression. A comparison between the experimental
data and model results has been also provided in this paper. 相似文献