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Search Results: 1 - 10 of 699271 matches for " D. L. A. MAJID "
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Heat Distribution in Rectangular Fins Using Efficient Finite Element and Differential Quadrature Methods  [PDF]
Engineering (ENG) , 2009, DOI: 10.4236/eng.2009.13018
Abstract: Finite element method (FEM) and differential quadrature method (DQM) are among important numerical techniques used in engineering analyses. Usually elements are sub-divided uniformly in FEM (conventional FEM, CFEM) to obtain temperature distribution behavior in a fin or plate. Hence, extra computational complexity is needed to obtain a fair solution with required accuracy. In this paper, non-uniform sub-elements are considered for FEM (efficient FEM, EFEM) solution to reduce the computational complex-ity. Then this EFEM is applied for the solution of one-dimensional heat transfer problem in a rectangular thin fin. The obtained results are compared with CFEM and efficient DQM (EDQM), with non-uniform mesh generation). It is found that the EFEM exhibit more accurate results than CFEM and EDQM showing its potentiality.
Computational Study on the Aerodynamic Performance of Wind Turbine Airfoil Fitted with Coand? Jet
H. Djojodihardjo,M. F. Abdul Hamid,A. A. Jaafar,S. Basri,F. I. Romli,F. Mustapha,A. S. Mohd Rafie,D. L. A. Abdul Majid
Journal of Renewable Energy , 2013, DOI: 10.1155/2013/839319
Abstract: Various methods of flow control for enhanced aerodynamic performance have been developed and applied to enhance and control the behavior of aerodynamic components. The use of Coand? effect for the enhancement of circulation and lift has gained renewed interest, in particular with the progress of CFD. The present work addresses the influence, effectiveness, and configuration of Coand?-jet fitted aerodynamic surface for improving lift and , specifically for S809 airfoil, with a view on its incorporation in the wind turbine. A simple two-dimensional CFD modeling using - turbulence model is utilized to reveal the key elements that could exhibit the desired performance for a series of S809 airfoil configurations. Parametric study performed indicates that the use of Coand?-jet S809 airfoil can only be effective in certain range of trailing edge rounding-off radius, Coand?-jet thickness, and momentum jet size. The location of the Coand?-jet was found to be effective when it is placed close to the trailing edge. The results are compared with experimental data for benchmarking. Three-dimensional configurations are synthesized using certain acceptable assumptions. A trade-off study on the S809 Coand? configured airfoil is needed to judge the optimum configuration of Coand?-jet fitted Wind-Turbine design. 1. Introduction In line with the efforts to enhance the use of green energy technology for energy extraction, conversion, and propulsion, the fundamental principles and mechanisms that play key roles in these technologies have been the focus in many current research efforts as well as the present research work, since these have the eventual potential of national development significance. Since one of the first attempts to generate electricity by using the wind in the United States by Charles Brush in 1888 [1], wind energy has been utilized for electricity generation using large Wind turbines in many wind farms with potential wind energy inland as well as off-shore. It has been estimated that roughly 10 million MW of energy are continuously available in the earth’s wind [2]. The technical potential of onshore wind energy is very large, 20 × 109 to 50 × 109?MWh per year against the current total annual world electricity consumption of about 15 × 109?MWh. The global wind power capacity installed in the year 2004 was 6614?MW, an increase in total installed generating capacity of nearly 20% from the preceding year. Wind energy conversion research and development efforts have their origin on fluid physics, thermodynamics, and material sciences. Learning from various
Fronto-ethmoidal mucocele as a cause of unilateral proptosis
Sen D,Puri N,Majid A
Indian Journal of Ophthalmology , 1979,
Effect of Age of Pipes on Performance of Natural Gas Transmission Pipeline Network System
A.D. Woldeyohannes,M.A.A. Majid
Journal of Applied Sciences , 2011,
Abstract: is capable of evaluating the effect of the age of pipe on the performance of the gas transmission system. In order to establish firm relationships between the age of the pipes and performance of the pipeline network system, further research is required.
Historical Data Based Models for Chilled Water Production from Waste Heat of Turbine
M. Amin A. Majid,A. Zainuddin,A.L. Tamiru
Journal of Applied Sciences , 2013,
Abstract: Performance analysis, optimization and environmental load assessment of an absorption system requires accurate but simplified models. The objective of the present study is to develop such models based on non-dimensional parameters (part load ratio, part-load factor and diverter damper position) and ordinary least squares. Since for the case study, the hourly, daily and monthly load demands data are available, the method of averaging over eight years is considered. The models are developed for a system comprised of two heat recovery steam generators and two steam absorption chillers. It was observed that the proposed method is effective in providing better picture of the relationships between the supplied heat and the amount of energy recovered by each subsystem. The maximum cooling load experienced by the two chillers was about 2392RT, which is 4.32% lower than the design capacity. The steam generators were found operating at part load ratio of about 0.41 only. Both chillers deteriorated in performance within the study period. This was confirmed by the part load ratio of 0.8 and steam consumption higher than that required for a new chiller. A generalized model was also identified for the two chillers with the correlation coefficient (R2), chi-square (χ2) and Root Mean Squared Error (RMSE) equals to 0.9996, 1.9765e-5 and 0.0044, respectively. The model was found accurate for cooling water temperatures in the range of 29 to 32°C.
An Improved Limit on the Rate Of Decay K+ -> pi+ mu+ e-
R. Appel,G. S. Atoyan,B. Bassalleck,D. R. Bergman,D. N. Brown,N. Cheung,S. Dhawan,H. Do,J. Egger,S. Eilerts,C. Felder,H. Fischer,M. Gach,W. Herold,V. V. Issakov,H. Kaspar,D. E. Kraus,D. M. Lazarus,L. Leipuner,P. Lichard,J. Lowe,J. Lozano,H. Ma,W. Majid,W. Menzel,S. Pislak,A. A. Poblaguev,V. E. Postoev,A. L. Proskurjakov,P. Rehak,P. Robmann,A. Sher,J. A. Thompson,P. Truoel,H. Weyer,M. E. Zeller
Physics , 2000, DOI: 10.1103/PhysRevLett.85.2450
Abstract: The experiment E865 at BNL places an upper limit on the branching ratio for the decay K+ -> pi+ mu+ e- of 3.9x10^-11 (90% C.L.). Along with with other results this yields a combined upper limit on this branching ratio of 2.8x10^-11. A new upper limit on the branching ratio for pi0 -> mu+ e- of 3.8x10^-10 (90% C.L.) is also established. The experiment and analysis are described.
Exotic Lolium perenne Varieties: Their Forage Value and Soil Cover Potential in Himalayas Region
S. D. Ahmad,M. Hammad,S.A. Majid
Journal of Biological Sciences , 2001,
Abstract: Rawalakot lies under humid temperate region at the height of 5500 ft from the sea level. The area is hilly and soils are prone to heavy erosion due to the loss of vegetative cover. Winter frost and snow often kills the local forages and thus depriving the livestock from green herbage altogether. Seven varieties of Lolium perenne (perennial ryegrass) from European and American germplasm were evaluated for their forage value and soil cover potential under Rawalakot conditions. All varieties compared were diploid (2n = 14). The comparison was based on plant height, fresh and dry matter yield, number of cuttings/ year and tillers plant-1. The variety VA88002 was found to be the best one in plant height and dry and fresh herbage yield followed by SERVO and APUS. When tiller number was compared, the variety APUS was found to be at the top followed by VA88001 and others. All varieties were of spreading nature with increasing persistence in following years and found to be suitable for cutting, grazing and soil conservation
Low-Cost Multi-Gigahertz Test Systems Using CMOS FPGAs and PECL
D. C. Keezer,C. Gray,A. Majid,N. Taher
Computer Science , 2007,
Abstract: This paper describes two research projects that develop new low-cost techniques for testing devices with multiple high-speed (2 to 5 Gbps) signals. Each project uses commercially available components to keep costs low, yet achieves performance characteristics comparable to (and in some ways exceeding) more expensive ATE. A common CMOS FPGA-based logic core provides flexibility, adaptability, and communication with controlling computers while customized positive emitter-coupled logic (PECL) achieves multi-gigahertz data rates with about $\pm$25ps timing accuracy.
Lie theory of finite simple groups and the Roth property
Javier López Pe?a,Shahn Majid,Konstanze Rietsch
Mathematics , 2010,
Abstract: In noncommutative geometry a `Lie algebra' or bidirectional bicovariant differential calculus on a finite group is provided by a choice of an ad-stable generating subset C stable under inversion. We study the associated Killing form. For the universal calculus associated to C=G \ {e} we show that the magnitude of the Killing form \mu=\sum_{a,b\in C}K^{-1}_{a,b} is defined for all finite groups (even when K is not invertible) and that a finite group is Roth, meaning its conjugation representation contains every irreducible, iff \mu\ is not equal to 1/(N-1), where N is the number of conjugacy classes. We show further that the Killing form is invertible in the Roth case, and that the Killing form restricted to the (N-1)-dimensional subspace of invariant vectors is invertible iff the finite group is almost-Roth group (meaning its conjugation representation has at most one missing irreducible). It is known that most finite simple groups are Roth and that all are almost Roth. At the other extreme from the universal calculus we prove that the generating conjugacy class in the case of the dihedral groups D_{2n} with n odd has invertible Killing form, and the same for the 2-cycles conjugacy class in any S_n. We also compute some eigenvalues of the Killing form in the case of the n-cycles class in S_n. Finally, we verify invertibility of the Killing forms of all real conjugacy classes in all nonabelian finite simple groups to order 75,000, by computer, and we conjecture this to extend to all nonabelian finite simple groups.
High statistics measurement of Ke4 decay properties
S. Pislak,R. Appel,G. S. Atoyan,B. Bassalleck,D. R. Bergman,N. Cheung,S. Dhawan,H. Do,J. Egger,S. Eilerts,H. Fischer,W. Herold,V. V. Issakov,H. Kaspar,D. E. Kraus,D. M. Lazarus,P. Lichard,J. Lowe,J. Lozano,H. Ma,W. Majid,A. A. Poblaguev,P. Rehak,A. Sher,Aleksey Sher,J. A. Thompson,P. Tru?l,M. E. Zeller
Statistics , 2003, DOI: 10.1103/PhysRevD.67.072004
Abstract: We report experimental details and results of a new measurement of the decay K+ -> pi+pi-e+nue (Ke4}. A sample of more than 400,000 Ke4 events with low background has been collected by Experiment 865 at the Brookhaven Alternate Gradient Synchrotron. From these data, the branching ratio (4.11+-0.01+-0.11)*10**(-5) and the pi-pi invariant mass dependence of the form factors F, G, and H of the weak hadronic current as well as the phase shift difference delta00-delta11 for pi-pi-scattering were extracted. Using constraints based on analyticity and chiral symmetry, a new value with considerably improved accuracy for the s-wave pi-pi-scattering length a00 has been obtained also: a00=0.216+-0.013 (stat.)+-0.002(syst.)+-0.002(theor.).
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