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991.
Khaled Moustafa 《Behaviour & Information Technology》2016,35(4):319-323
Reading scientific papers in portable document format (PDF)-columned formats on computer screens is sometimes daunting and unfriendly. This is mainly due to the fact that PDF-columned texts are often truncated from the top or the bottom of pages so that readers have to scroll up–down repeatedly in the same page to get the whole text read. To make the reading process as smooth as possible, PDF viewers should be designed as responsive tools with responsive layouts that should automatically adapt the amount of readable text to the sizes of the displaying monitors so that readers will not waste time in repetitive vertical and horizontal scrolling movements within the same page. Here, I discuss such a problem-solving proposal that could be implemented in PDF viewers to improve the readability of PDF-columned texts and to make the reading process as flexible and painless as possible. 相似文献
992.
Khaled Daqrouq 《Engineering Applications of Artificial Intelligence》2011,24(5):796-802
In the present study, the techniques of wavelet transform (WT) and neural network were developed for speech based text-independent speaker identification. The first five formants in conjunction with the Shannon entropy of wavelet packet (WP) upon level four features extraction method was developed. Thirty-five features were fed to feed-forward backpropagation neural networks (FFPBNN) for classification. The functions of features extraction and classification are performed using the wavelet packet and formants neural networks (WPFNN) expert system. The declared results show that the proposed method can make an effectual analysis with average identification rates reaching 91.09. Two published methods were investigated for comparison. The best recognition rate selection obtained was for WPFNN. Discrete wavelet transform (DWT) was studied to improve the system robustness against the noise of −2 dB. 相似文献
993.
Simulation time for the classical problem of Lattice Quantum Chromodynamics (Lattice QCD) is dominated by one kernel routine responsible for computing the actions of a Dirac operator. This paper describes an experience in parallelizing this kernel routine. We explore parallelization granularities for this kernel routine on Graphical Processing Units (GPUs). We show that fine-grained parallelism can outperform coarse-grained parallelization, given that control-flow and communication effects are minimized. We propose two techniques for transforming control-flow-based code to control-free code. We also show how to reduce the communication effect by optimizing for commonly used sequences of calls to this routine. In our implementation on NVIDIA 8800 GTX, we were able to achieve an 8.3x speedup over an SSE2 optimized version on 2.8 GHz Intel Xeon CPU. 相似文献
994.
Khaled M. Gharaibeh 《国际射频与微波计算机辅助工程杂志》2009,19(4):502-511
A simulation procedure of noise figure (NF) of nonlinear amplifiers is developed. NF is defined in terms of the effective signal‐to‐noise ratio (SNR) at the output of a nonlinear amplifier. The effective output SNR when the input consists of a communication signal plus Gaussian noise is evaluated through the identification of the effective output noise and nonlinear distortion power using the orthogonalization of the nonlinear model. The approach is useful for the assessment of noise performance of low‐noise amplifiers in wireless systems. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE 2009. 相似文献
995.
Leonid Khachiyan Endre Boros Konrad Borys Khaled Elbassioni Vladimir Gurvich Gabor Rudolf Jihui Zhao 《Theory of Computing Systems》2008,43(2):204-233
Given a directed graph G=(V,A) with a non-negative weight (length) function on its arcs w:A→ℝ+ and two terminals s,t∈V, our goal is to destroy all short directed paths from s to t in G by eliminating some arcs of A. This is known as the short paths interdiction problem. We consider several versions of it, and in each case analyze two subcases: total limited interdiction, when a fixed number k of arcs can be removed, and node-wise limited interdiction, when for each node v∈V a fixed number k(v) of out-going arcs can be removed. Our results indicate that the latter subcase is always easier than the former one. In
particular, we show that the short paths node-wise interdiction problem can be efficiently solved by an extension of Dijkstra’s
algorithm. In contrast, the short paths total interdiction problem is known to be NP-hard. We strengthen this hardness result
by deriving the following inapproximability bounds: Given k, it is NP-hard to approximate within a factor c<2 the maximum s–t distance d(s,t) obtainable by removing (at most) k arcs from G. Furthermore, given d, it is NP-hard to approximate within a factor
the minimum number of arcs which has to be removed to guarantee d(s,t)≥d. Finally, we also show that the same inapproximability bounds hold for undirected graphs and/or node elimination.
This research was supported in part by NSF grant IIS-0118635 and by DIMACS, the NSF Center for Discrete Mathematics & Theoretical
Computer Science. Preprints DTR-2005-04 and DTR-2006-13 are available at and .
Our co-author Leonid Khachiyan passed away with tragic suddenness on April 29th, 2005. 相似文献
996.
Jabri Khaled Takayuki Komatsu Kazumasa Matusita Ryuji Sato 《Journal of Materials Science: Materials in Electronics》1996,7(4):261-266
The formation mechanism of the high-T
c phase through the glass-ceramic route and the role of Pb on the formation of this phase have been investigated. It was found that a new compound with the chemical composition Pb2Sr3 – x
Ca
x
CuO
y
(x = 1.8) precipitates at around 550C. This phase is stable up to 800C, where it begins to decompose, and at 850 C it completely disappears. It was found that some part of the released Pb diffuses into the 2212 phase leading to the formation of Pb-containing 2212 phase, (Bi, Pb)2Sr2CaCu2O
x
. On the other hand, an endothermic peak, probably arising from the melting of (Bi, Pb)2Sr2CaCu2O
x
phase or melting at grain boundaries containing Pb2+, was observed at 856C only in Pb-containing samples that were heat treated. The liquid phase attributed to the endothermic peak may enhance the formation of high-T
c phase (2223 phase). The growth kinetics for the high-T
c phase were analysed using the Johnson-Mehl-Avrami equation; the results indicate that the growth of the high-T
c phase is controlled by a diffusion process and the activation energy for its formation in the initial stage (shorter than 96 h) is 576 ± 45 kJ mol–1. 相似文献
997.
Waheed A. Badawy Khaled M. Ismail Ziad M. Khalifa 《Journal of Applied Electrochemistry》2007,37(5):593-604
Uniform conducting polymer films of poly(N-(1-Naphthyl) ethylene-diamine dihydrochloride), PNED, were prepared conveniently and reproducibly by the anodic oxidation
of the monomer, N-(1-Naphthyl) ethylene-diamine dihydrochloride, NED, in an acidic aqueous solution using the conventional potentiodynamic
technique. The different parameters influencing the preparation conditions like monomer concentration, solvent constitution,
scan range, scan rate, scan repetition, rotation speed of the working electrode and the type of the substrate were investigated
and the optimum preparation conditions are specified. The stability of the prepared films was tested in both aqueous and non-aqueous
media. The characteristics of the polymer films and their electrochemical activity towards catalyzing some technologically
promising redox reactions were also examined. The films were found to be very stable in aqueous solutions and in some organic
solvents like acetone, acetonitrile, and chloroform and dimethyl sulfoxide. The film stability was found to depend on the
solution pH. The polymer films were capable of catalyzing the redox processes of several natural products and amino acids
e.g. vitamin C and glycine. The polymer film possesses electrochromic properties and the color of the film changes from purple
to violet to dark blue and then to brown according to the preparation and/or polarization conditions. The electrochromic properties
are related to polaron formation, which subsequently oxidizes to diimine species followed by the oxidation of the aromatic
ring. The mechanism of the polymerization process was investigated and discussed. The process involves deprotonation reactions
and a head-to-tail coupling of the oxidized monomer with cation radicals.
An erratum to this article can be found at 相似文献
998.
Khaled M. Gharaibeh 《国际射频与微波计算机辅助工程杂志》2014,24(6):656-664
Orthogonal frequency division multiplexed (OFDM) signals have high peak‐to‐average power ratio (PAPR) which results in excessive nonlinear distortion when amplified by power amplifiers (PA) and hence, reduction in system signal‐to‐noise (SNR) and spectral efficiency. Clipping has been one of the most popular and low‐cost technique for reducing the PAPR of OFDM signals. The overall spectral efficiency of an OFDM system that involves clipping depends on the combined response of the cascade of clipper‐amplifier and not only on the response of the clipper. In this article, the performance of clipped and nonlinearly amplified OFDM signals is studied. The combined response of a clipper‐amplifier cascade is obtained using an orthogonalized behavioral model which enables in‐band and out‐of‐band nonlinear distortions to be accurately predicted without using the Gaussian assumption of signal statistics. Furthermore, different clipping characteristics are studied where it is shown that the overall nonlinear distortion, and hence the overall SNR, is highly dependent on the type of clipping characteristics and the clipping ratio. Simulation results are verified by Simulink measurement model which uses measured amplifier characteristics in a “General Amplifier” block. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:656–664, 2014. 相似文献
999.
Ammar?Cherif Khaled?Sebei Sadok?Boukhchina Habib?Kallel Khaled?BelkacemiEmail author Joseph?Arul 《Journal of the American Oil Chemists' Society》2004,81(10):901-905
The kernel oil content, kernel FA and TAG composition, kernel moisture content, and kernel weight as well as fruit weight
of three almond cultivars (Achaak, Mazetto, and Perlees) were monitored during the maturation of kernels. Lipid fractions
of all almond samples were extracted using a mixture of chloroform and methanol. FAMF and TAG contained in these fractions
were analyzed by GC and HPLC, respectively. The ratio of kernel to fruit weight appears to be a good indicator of almond kernel
development. The total lipid content of developing almond kernels exhibited a sigmoidal pattern with time, similar to seeds
and kernels of other higher plants; the cultivar Achaak showed a higher rate of lipid accumulation. The proportion of eleic
acid (0) dominated at the later stage of maturation for all three almond cultivars. Although there was no significant difference
in the FA composition for the three cultivars studied, marked differences were observed in their TAG profiles. Ten TAG species
identified were LLL, LLO, LnOO, LOO, LOP, PLP, OOO, POO, POP, and SOO, where L represents linoleic acid; Ln, linolenic acid;
P, palmitic acid; and S, stearic acid. The difference in the TAG profile can be useful for distinguishing various cultivars.
The oil of Mazetto cultivar kernes exhibited a TAG composition comparable to that of olive oil. 相似文献
1000.
The current article describes static and frictional contact tests carried out with spherical indenter on both human skin surface and elastomeric materials. This tribological study is performed to analyze the elasticity and tactile properties of the human skin, and therefore to evaluate reliability of human skin behavior simulation through the considered elastomeric materials. Finite element analyses of indentation tests are proposed. Critical normal load was found when numerical and experimental results were confronted. Such critical force defines the limit of elastic model application. POLYM. ENG. SCI., 46:1715–1720, 2006. © 2006 Society of Plastics Engineers 相似文献