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91.
Wen-Yan Yin Le-Wei Li Tat-Soon Yeo Mook-Seng Leong 《Electromagnetic Compatibility, IEEE Transactions on》2000,42(4):330-338
A generalized mathematical procedure is developed for investigating a TEz-polarized plane wave penetration through two-dimensional (2-D) multilayered cylindrical cavity-backed apertures. The mathematical treatment is based on the direct integral equation technique combined with the Galerkin's procedure. Both the near- and far-zone field solutions to such a multiple coupling system are obtained in an analytical form. By taking the aperture edge effects into account, the magnetic currents on the surrounded multiple apertures are expanded in terms of a series of Chebyshev polynomials of the first kind. Furthermore, parametric studies are performed to show the variation of the penetrated near-zone magnetic field in various cylindrical cavity-backed apertures with the aperture number and geometrical sizes 相似文献
92.
Polishchuk I. Yee-Chia Yeo Qiang Lu Tsu-Jae King Chenming Hu 《Device and Materials Reliability, IEEE Transactions on》2001,1(3):158-162
The degradation of 100-nm effective channel length pMOS transistors with 14 Å equivalent oxide thickness Jet Vapor Deposition (JVD) Si3N4 gate dielectric under hot-carrier stress is studied. Interface-state generation is identified as the dominant degradation mechanism. Hot-carrier-induced gate leakage may become a new reliability concern. Hot-carrier reliability of 14 Å Si3N4 transistors is compared to reliability of 16 Å SiO2 transistors 相似文献
93.
Joo-Hyoung Park Sang Jun Park Hee Ah Ahn In-Sik Nam Gwon Koo Yeo Jeong Ki Kil Young Kee Youn 《Microporous and mesoporous materials》2009,117(1-2):178-184
Libraries consisting of more than 100 zeolite samples were prepared and examined for developing a promising HC trap catalyst. Parallel adsorptions of toluene onto the catalyst samples were conducted over a 10 × 10 array reactor under dry and wet conditions with or without a heating process three knowledge-based conditions for developing an automotive catalyst during the cold-start period. FAU and BEA type zeolites revealed a high performance of toluene adsorption under the dry condition. However, FAU type zeolite significantly decreased the amount of toluene adsorbed in the presence of water in the feed gas stream, mainly due to the hydrophobicity of the catalyst surface. Over Beta type zeolites, the toluene adsorbed was found to be considerably preserved, even after forced desorption temperature-ramping to the warm-up condition of an automotive engine. Li, K, or Ag ion-exchanged Beta zeolites seem to be particularly promising as an HC trap catalyst. 相似文献
94.
Xin Guo Hongbo Sun Tat Soon Yeo 《Geoscience and Remote Sensing, IEEE Transactions on》2008,46(7):1879-1891
The performance of high-frequency surface wave radar (HFSWR) is known to suffer from external environmental interference and noise, such as cochannel radio-frequency interference from other radiating source, ionospheric clutter, lightning impulsive noise, etc. This paper experimentally evaluates the interference cancellation performance of various adaptive beamforming schemes with respect to the aforementioned three types of interferences in an attempt to find the most promising adaptive cancellation scheme in practical HFSWR environment. 相似文献
95.
Le-Wei Li Xiao-Kang Kang Mook-Seng Leong Pang-Shyan Kooi Tat-Soon Yeo 《Microwave Theory and Techniques》2001,49(3):532-541
Dyadic Green's functions (DGFs) and their scattering coefficients are formulated in this paper for defining the electromagnetic fields in multilayered spheroidal structures. The principle of scattering superposition is applied, in a similar form of the DGF in an unbounded medium under spheroidal coordinates, the scattering DGFs due to multiple spheroidal interfaces are expanded in terms of the spheroidal vector wave functions. For the lack of general orthogonality of the spheroidal radial and angular functions, the Green's dyadics are expressed in a different way where the coordinate unit vectors are also combined in the construction, as compared with the conventional form of vector wave eigenfunction expansion. The matrix equation systems satisfied by the coupled scattering (i.e., reflection and transmission) coefficients of the DGFs are obtained so that these coefficients can be solved uniquely. The DGFs can be employed to investigate effects of spheroidal radomes used to protect the airborne or satellite antenna systems and of handy phone radiation near the spheroid-shaped human head, and so forth. Numerical calculations about the applications of the formulated multilayered DGFs are presented in part II of this paper 相似文献
96.
Chun Sum Ng Yi Hui Lu Tat Soun Yeo Cheng Bo Zhang 《Geoscience and Remote Sensing, IEEE Transactions on》2000,38(1):374-382
A new technique for inversed synthetic aperture radar (ISAR) ranging, which resembles the principle of the Vernier measuring system, is presented. In this technique, the transmitted ISAR pulse comprises a train of chirp subpulses with uniformly stepped up center frequencies. The return ISAR echo is first processed, using hardware, to determine a coarse estimate of the target range. Further refinements of the range estimate are achieved through software processing, consisting of two stages of discrete Fourier transform operation. The ranging accuracy can be increased without the need for increased bandwidth, but at the expense of a slight increase in computational complexity. Numerical evaluation shows that a noiseless system is capable of achieving high-ranging accuracy, of the order of millimeters, even in the presence of dispersion and target motion. From computer simulations, the proposed system is also found to be robust against additive system noise and frequency jitter under practical conditions 相似文献
97.
A long period grating (LPG) coated with polyvinyl alcohol has been developed and evaluated through exposure to a range of relative humidity (RH) levels (from 33%RH to 97%RH). The conditions for the creation of the sensor probes are described and the response of the device in terms of changes in the resonance loss of several of the spectral loss bands has been monitored. In order to make comparative measurements, a noncoated LPG was exposed to various known refractive index (RI) conditions and the grating response was monitored, analyzed and the results evaluated. This is then related to the change in RH when the sensor is exposed to various RH levels, as the coating RI changes, leading to the change in resonance loss. The PVA coated LPG sensor is showing a relatively fast response time of ~ 80 s to reach 97%RH from 33%RH and inducing ~ 2 dB change in transmission of resonance loss band. 相似文献
98.
亚洲的近代工业受到英国工业革命的巨大影响,亚洲的工业遗产研究和保护也是在国际工业遗产保护的背景下发展起来的。日本产业遗产研究始于20世纪70年代,中国的工业遗产研究自2006年呈现出明显的上升趋势,至今仍然正在推进中。中日的工业遗产研究和保护有着不同的特色,采取中日比较的方法探究两国工业遗产在研究和发展历程、调查和评估方法、文物指定情况等方面的异同,考察国际工业遗产保护在亚洲的发展,同时加强亚洲工业遗产研究的学术交流和互相借鉴。提出如下建议:1)基础研究依然是下个阶段中国工业遗产研究的重要任务;2)应该尽快推进全国的普查;3)中国的数据库建设和评估工作有待进一步深入。 相似文献
99.
Tae Chang Park Tae Young Kim Yeong Koo Yeo 《Korean Journal of Chemical Engineering》2010,27(6):1662-1668
In polyolefin processes the melt flow index (MFI) is the most important control variable indicating product quality. Because
of the difficulty in the on-line measurement of MFI, a large number of MFI estimation and correlation methods have been proposed.
In this work, mechanical predicting methods such as partial least squares (PLS) method and support vector regression (SVR)
method are employed in contrast to conventional dynamic prediction schemes. Results of predictions are compared with other
prediction results obtained from various dynamic prediction schemes to evaluate predicting performance. Hourly MFIs are predicted
and compared with operation data for the high density polyethylene process involving frequent grade changes. We can see that
PLS and SVR exhibit excellent predicting performance even for severe operating situations accompanying frequent grade changes. 相似文献
100.
In current Peer-to-Peer streaming applications, a lot of research attempts to provide timely stream services to the end users.
Most of them focus on how to organize the peer connections into an efficient overlay network. Due to the variation in the
network, a lot of overhead is generated when the overlay structure adapts to the changes. In order to minimize the impact
of network fluctuation, we proposed a scheduling algorithm which helps to distribute stream data efficiently through the fluctuating
networks. It needs only partial information about overlay structure and provides the services to satisfy most number of users.
The global latency experienced by peers in the system is thus minimized. To alleviate the problem of packet loss along the
overlay, we introduce retransmission requests into our scheduling algorithm. Requests for much needed data are treated with
higher priority. Parent peers which receive the request will re-send the missing data to minimize the loss impact. The missing
data which are needed by more peers will have a larger cumulative impact through the tree overlay and these are thus scheduled
and sent earlier. Simulation results showed that our prioritization and scheduling algorithm minimizes the negative impact
of fluctuation and data loss in a dynamic network environment. 相似文献