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排序方式: 共有1180条查询结果,搜索用时 15 毫秒
101.
Han T. Choi Jeffrey S. West Khaled A. Soudki 《Construction and Building Materials》2011,25(5):2441-2449
A partially bonded strengthening approach for reinforced concrete (RC) beams utilizing near-surface-mounted (NSM) carbon fiber reinforced polymer (CFRP) bars was investigated with the specific objective of improving deformability. A total of six RC T-beams strengthened with NSM CFRP bars of various unbonded lengths were tested. Test results showed a decrease of the stiffness at the post-yield stage of the load–deflection response in the partially bonded beams. This is caused by the delayed increase of the FRP strain within the unbonded length. As a result the beam deformability was increased as the unbonded length increased at the same applied load. Internal slip of the FRP bar and gradual concrete failure were observed near the ultimate state, which caused a complicate nonlinear behavior of the beams. An analytical model is proposed to address the complete beam behavior including the effect of slip of FRP reinforcement and gradual concrete crushing. This model was developed based on the compatibility of deformation of the partially bonded system and was able to represent the ultimate behavior of the beams well. 相似文献
102.
Khaled Daqrouq Ibrahim N. Abu-Isbeih Omar Daoud Emad Khalaf 《International Journal of Speech Technology》2010,13(2):101-115
This paper investigates the utilization of wavelet filters via multistage convolution by Reverse Biorthogonal Wavelets (RBW)
in high and low pass band frequency parts of speech signal. Speech signal is decomposed into two pass bands of frequency;
high and low, and then the noise is removed in each band individually in different stages via wavelet filters. This approach
provides better outcomes because it does not cut the speech information, which occurs when utilizing conventional thresholding.
We tested the proposed method via several noise probability distribution functions. Subjective evaluation is engaged in conjunction
with objective evaluation to accomplish optimal investigation method. The method is simple but has surprise high quality results.
The method shows superiority over Donoho and Johnstone thresholding method and Birge-Massart thresholding strategy method. 相似文献
103.
Raphael C.-W. Phan Jiang Wu Khaled Ouafi Douglas R. Stinson 《Wireless Personal Communications》2011,61(1):69-81
In this paper, we analyze the first known provably secure Radio Frequency Identification (RFID) authentication schemes that
are designed to provide forward untraceability and backward untraceability: the L-K and S-M schemes. We show how to trace
tags in the L-K scheme without needing to corrupt tags. We also show that if a standard cryptographic pseudorandom bit generator (PRBG) is used in the S-M scheme, then the scheme may fail to provide forward untraceability
and backward untraceability. To achieve the desired untraceability features, we show that the S-M scheme can use a robust PRBG which provides forward security and backward security. We also note that the backward security is stronger than necessary
for the backward untraceability of the S-M scheme. 相似文献
104.
K. A. Khaled 《Journal of Petroleum Geology》1999,22(4):377-395
The Abu Gharadig oil- and gasfield is located in the north of the Western Desert of Egypt. In this paper, the geochemical characteristics of kerogens from Cretaceous shales at this field are described. The shale samples came from the Abu Roash Formation E and G Members (late Cenomanian- Turonian), the Bahariya Formation (early Cenomanian) and the Betty Formation (Neocomian- Barremian). Kerogen type and quality was evaluated by optical microscopy and by standard methods (elemental analysis, infrared spectroscopy and Rock-Eval pyrolysis). The results show that the shale samples analysed contain fair to high quantities of organic matter, and that this takes the form of marine amorphous sapropelic and structured liptinite macerals which can be classified as Types I and II kerogens.
Maturation indicators and burial history curves indicate that shales from the Abu Roash E and G Members are currently located in the oil-generation window. Oil generation in these units has taken place since the late Palaeocene-early Eocene—i.e. since the formation of structural traps in the Abu Gharadig area, which occurred in the Maastrichtian—Eocene. Shales in the Bahariya and Betty Formations passed through the oil window during the Late Cretaceous before the traps were formed, but the shales reached the wet-gas zone in the late Miocene - early Pliocene.
Most of the liquid hydrocarbons in the Abu Gharadig field are sourced by Cretaceous shales in the Abu Roash E and G Members; and most gas is generated by shales in the underlying Bahariya and Betty Formations. The Jurassic Khatatba Formation may also have generated some gas. 相似文献
Maturation indicators and burial history curves indicate that shales from the Abu Roash E and G Members are currently located in the oil-generation window. Oil generation in these units has taken place since the late Palaeocene-early Eocene—i.e. since the formation of structural traps in the Abu Gharadig area, which occurred in the Maastrichtian—Eocene. Shales in the Bahariya and Betty Formations passed through the oil window during the Late Cretaceous before the traps were formed, but the shales reached the wet-gas zone in the late Miocene - early Pliocene.
Most of the liquid hydrocarbons in the Abu Gharadig field are sourced by Cretaceous shales in the Abu Roash E and G Members; and most gas is generated by shales in the underlying Bahariya and Betty Formations. The Jurassic Khatatba Formation may also have generated some gas. 相似文献
105.
A solid solution of vanadium (V)-doped tin oxide (SnO2 ) particles of average diameter 2 nm and V content of 19 at.% was prepared at normal pressure and low temperature (100°C) by mixing wet SnO2 gel SnO2 · x H2 O with a boiling solution of vanadium oxide (V2 O5 ). Experimental characterizations using X-ray, electron diffraction, and transmission electron microscope show evidence of a pure single phase. The nanoparticles exhibit a mixed magnetic behavior, namely paramagnetic and ferromagnetic. Their thermal stability is also investigated. At higher temperature, 850°C, some amount of Fe precipitates from the solid solution. 相似文献
106.
Ga2O3, Se metal, SnO, Sb2O3, HgO and PbCO3 are formed upon the reaction of acetamide aqueous solutions with Ga(NO3)3, SeO2, SnCl2, SbCl3, HgCl2 and Pb(NO3)2, respectively, at 90°C. Different amorphous or crystalline phases can be obtained depending upon the experimental conditions (molar ratios, metal salts and temperature). The chemical mechanisms for the formations of this metal, oxides or carbonate are discussed and the X-ray diffraction, scanning electron microscopy (SEM) and atomic force microscope (AFM) are described. The type of metal ions plays an important role in the decomposition of acetamide, leading to the formation of solid stable (metal, oxides or carbonate), soluble and gases species. These new precursors are more stable preventing the rapid precipitation of metal, oxides or carbonate. Furthermore, this route allows the formation of pure compounds in solutions. 相似文献
107.
Khaled Elmawazini Gamal Atallah Sonny Nwankwo Yazid Dissou 《Industry and innovation》2013,20(1):69-91
In this study, we use a cross-sectionally correlated and timewise autoregressive model and panel data for the period 1966–2000 to investigate human development as a measure of host country absorptive capacity in 30 developed and developing countries. The results suggest that technology diffusion from US foreign affiliates has a positive and significant impact on labor productivity only if host countries have a minimum level of human development. This condition may partially explain why previous studies show mixed support for the hypothesis that foreign affiliates have a positive effect on productivity in developing countries. Although the results have to be interpreted with caution, the policy implication is that human development enhances the capacity of countries to reap the benefits of foreign direct investments. 相似文献
108.
Khaled M. El-Sawy Amr M.I. Sweedan 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2010,25(6):689-701
The paper reports the results of an extensive numerical simulation to estimate the elastic buckling pressure and the corresponding thrust and bending moment induced in loosely fitted thin liners. The study is conducted numerically using a two-dimensional (2D) non-linear finite element model that accounts for the effects of large deformations on the stability of loosely fitted liners. The finite element results together with a non-linear multi-variant regression analysis are used to develop simplified non-dimensional formulae that provide the critical pressure, thrust and bending moments, at buckling, based on the liner’s geometry and material properties.In addition, several other analytical and numerical solutions for the same problem are revisited and critically reviewed. For comparison purposes, two of such methods are extended to allow for the calculation of the thrust and bending moment developed at the most heavily stressed point in the loosely fitted liners at the onset of buckling. In general, the comparison reveals the appropriateness of the proposed regression models in predicting the critical pressure and the associated thrust and bending moment induced in imperfect loosely fitted liners. Developed formulae provide designers with a simple and reliable means for ensuring stability and safety of such special type of structures. 相似文献
109.
Abstract Integrated water resources planning and management are considered very complex issues. These issues are usually addressed through the multi-sectoral, interdisciplinary and hierarchal decomposition approaches. In general, integrated resource management indicates the consideration of water, social, socio-economic, economic and environmental issues. The current study aims at merging the GIS and Multi-Criteria Evaluation (MCE) techniques for the integrated water resource management of a cropped area. An area of about 120,000 Hectares located in the Northern Nile River Delta area with a coastal zone on the Mediterranean was selected and GIS was applied to represent the area's different environment, social, economic, and water factors. Different randomization cropping pattern distribution scenarios were proposed. Through the merging of GIS and MCE approaches, three scenarios were run and evaluated at three different levels: farm, canal catchment area and whole area. This merging resulted in a very powerful tool for the evaluation of different plans. The merging of GIS and MCE really facilitated the decision making process for these types of integrated water management problems. 相似文献
110.
Masugi Inoue Khaled Mahmud Homare Murakami Mikio Hasegawa Hiroyuki Morikawa 《Wireless Personal Communications》2005,35(1-2):53-70
A context-based adaptive communication system is introduced for use in heterogeneous networks. Context includes the user's
presence, location, available network interfaces, network availability, network priority, communication status, terminal features,
and installed applications. An experimental system was developed to clarify the feasibility of using context information to
flexibly control networks and applications. The system operates on a seamless networking platform we developed for heterogeneous
networks. By using contexts, the system can inform the caller and callee of applications they can access, which are available
through the network before communication occurs. Changes in contexts can switch an on-going application to another during
actual communication. These functions provide unprecedented styles of communication. A business scenario for a seamless networking
provider is also presented.
Dr. Morikawa has also been in charge of NICT's Mobile Networking Group.
Masugi Inoue received his B.E. from Kyoto University in 1992 and his M.E. and D.E. from the University of Tokyo in 1994 and 1997, all
in the field of Electrical Engineering. He is currently a senior researcher at the Yokosuka Radio Communications Research
Center under the National Institute of Information and Communications Technology (NICT), Japan, and has been engaged in R&D
on ultrahigh-speed WLANs and mobile networking. He joined the Communications Research Laboratory (CRL) of the Ministry of
Posts and Telecommunications, Japan, in 1997, which was reorganized as NICT in April 2004. He was a visiting researcher at
Polytechnic University in Brooklyn, New York in 2000.
Khaled Mahmud received his B.Sc. (Eng.) in Electrical and Electronics Engineering from the Bangladesh University of Engineering and Technology
in Dhaka in 1991. He received his M.E. and Ph.D. in the same field from Shizuoka University in Japan, in 1997 and 2000, respectively.
He was a research fellow at NICT, Japan, from 2000 to 2004. He is currently an Assistant Professor in the Department of Computer
Science and Engineering at North South University, Bangladesh. His research interests include modulation-demodulation techniques,
software radio, mobile communication systems, wireless Internet, and IP mobility technologies.
Homare Murakami received his B.E. and M.E. in Electronic Engineering from Hokkaido University in 1997 and 1999. In 2004, he received the
Young Investigators Award from IEICE. He is currently a researcher at NICT's Mobile Networking Group. He is also an industrial
PhD student in Aalborg University since 2003. His interest areas are naming scheme, wireless TCP and new transport protocol,
IP mobility, fast handover method, and location management.
Mikio Hasegawa received his B. Eng, M. Eng., and Dr. Eng. in 1995, 1997, and 2000 from Science University of Tokyo. From 1997 to 2000, he
was a Research Fellow of the Japan Society for the Promotion of Science (JSPS). He is currently a senior researcher in Mobile
Networking Group, National Institute of Information and Communications Technology, and a technical advisor in ChaosWare Inc.
His research interests include applications of chaotic dynamical theory, combinatorial optimization, mobile networks, and
ubiquitous computing.
Hiroyuki Morikawa received his B.E., M.E., and D.E. in Electrical Engineering from the University of Tokyo in 1987, 1989, and 1992. He is currently
an Associate Professor in the Department of Frontier Informatics at the University of Tokyo and is in charge of NICT's Mobile
Networking Group. His research interests are in the areas of computer networks, mobile computing/networks, ubiquitous computing,
and network services. He serves as Editor of Transactions of the IEICE and has been on the technical program committees of
IEEE/ACM conferences and workshops. He sits on numerous telecommunications advisory committees and frequently serves as a
consultant to the government. 相似文献