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21.
In this paper, theoretical symbol error probability (SEP) expressions are derived for orthogonal space-time block code (OSTBC) diversity systems employing arbitrary rectangular M-QAM transmission over flat Rayleigh fading channels. Independent fading between diversity channels is assumed. Channel average powers may be distinctive, identical, or mixed with both. The rectangular M-QAM results are extended to square M-QAM, M-PAM, and binary antipodal signaling. All derived expressions are in elementary forms without complicated high-order transcendental functions and unevaluated integrals and, hence, are strictly exact and can be readily simulated by the computer. Moreover, it is shown that mixed Rayleigh fading results can be readily extended to various Nakagami-m fading results. A four-transmit-antenna system with a half-rate OSTBC for 16-QAM signaling is used to demonstrate that the theoretical result is in excellent agreement with the Monte Carlo simulated result. From simulation curves, it is shown that, under the independent channel fading condition, channels with identical powers have better error rate performance than channels with distinctive powers. 相似文献
22.
Kazem M. Sadeghi Mohammad-Ali Sadeghi Teh Fu Yen 《Petroleum Science and Technology》1990,8(7):769-791
Reducible aromatic species in coal liquid products from five major processes (Synthoil, FMC COED, HRI H-Coal, PAMCO SRC, and Catalytic Inc. SRC) together with solvent elution chromatography fractions of a selected asphaltene has been evaluated. The half-wave potentials measurments are found to be consistant with other methods. The total polarographic reduction of measurement per average molecule for Synthoil solvent fractions, as measured by diffusion constant (id/C), increases in the following manner: gas oil → resin → asphaltene → carbene → carboid. The same trend was observed when color indices (I) and refractive indices (n25) were individually studied. 相似文献
23.
Chun‐Hong Kuo Yi‐Ting Chu Yen‐Fang Song Michael H. Huang 《Advanced functional materials》2011,21(4):792-797
Cubic and octahedral Cu2O nanocrystals and Au–Cu2O core–shell heterostructures are used as sacrificial templates for the growth of Cu2S nanocages and Au–Cu2S core–cage structures. A rapid sulfidation process involving a surface reaction of Cu2O nanocrystals with Na2S, followed by etching of the Cu2O cores with HCl solution for ≈5 sec, results in the fabrication of Cu2S cages with a wall thickness of 10–20 nm. Transmission electron microscopy characterization reveals the formation of crystalline walls and the presence of ultrasmall pores with sizes of 1 nm or less. Formation of Cu2O–Cu2S core–shell structures and their conversion into Cu2S cages is verified by UV–vis absorption spectroscopy. X‐ray photoelectron spectra further confirm the composition of the cages as Cu2S. The entire hollowing process via the Kirkendall effect is recorded using in‐situ transmission X‐ray microscopy. After shell formation, continuous ionic diffusion removes the interior Cu2O. Intermediate structures with remaining central Cu2O portions and bridging arms to the surrounding cages are observed. The nanocages are also shown to allow molecular transport: anthracene and pyrene penetration into the cages leads to enhanced fluorescence quenching immediately upon adsorption onto the surfaces of the encapsulated gold nanocrystals. 相似文献
24.
A 96-element conformal array controlled by photonics was built and tested for airborne radars. The L-band array consists of 1 km fibre-optic links and a photonic time shift network. There was no beam squint (shift in angle) as the frequency sweeps over the entire band (850-1400 MHz). A nanosecond impulse response was measured to demonstrate a 50% instantaneous bandwidth (550 MHz), corresponding to a 30 cm range resolution 相似文献
25.
Yee-Wen Yen H. W. Tseng K. Zeng S. J. Wang C. Y. Liu 《Journal of Electronic Materials》2009,38(11):2257-2263
The cross-interaction between Sn/Cu and Sn/Au interfacial reactions in an Au/Sn/Cu sandwich structure was studied. Field-emission
electron probe microanalysis (FE-EPMA) revealed that the Cu content in the three Au-Sn phases (AuSn, AuSn2, and AuSn4) was very low, less than 1 at.%. This means␣that Cu from the opposite Cu foil did not participate in the interfacial reaction
at the Sn/Au interface. On the opposite Sn/Cu side, Au-substituted (Cu,Au)6Sn5 formed within the initial 1 min of reflow. With prolonged reflow, the Au content in the Au-substituted (Cu,Au)6Sn5 increased and it transformed into a Cu-substituted (Au,Cu)Sn phase with 25 at.% Cu after 1 min of reflow at 250°C. The x-ray
diffraction (XRD) pattern confirmed the phase transformation of Au-substituted (Cu,Au)6Sn5 to Cu-substituted (Au,Cu)Sn phase. In addition, there was greater Au consumption in the Au/Sn/Cu sandwich joint structure
than in the single Au/Sn reaction case, due to some of the Au participating in the opposite Sn/Cu interfacial reaction. 相似文献
26.
Der-Rong Din Chian-Ya Hong Hsiao-Suang Yen Ya-Hsin Chuang Xin-Kai Lin 《Photonic Network Communications》2013,26(2-3):150-160
For a delay-constrained multicast transmission request, the goal of delay-constrained survivable multicast routing problem is to provide the primary multicast tree and the tree protecting sparse resources. The shared segment-based protection (SSBP) method is used in this article to protect the delay-constrained multicast transmission. Two heuristic methods are proposed to find the delay-constrained primary tree and the backup segments with delay constraint. Experiments are conducted to evaluate the performance of the proposed methods, and the performance to be evaluated includes wavelength efficiency ratio (WER), blocking ratio (BR), and executing time. Simulations show that the SSBP method can get better BR and WER than the previous results demonstrated Din and Jiang (Comput Commun 35(10):1172–1184, 2012). 相似文献
27.
Yun‐Sheng Yen Ruay‐Shiung Chang Chuan‐Yung Wu 《Wireless Communications and Mobile Computing》2013,13(2):157-169
The advance of computer network technologies such as IEEE 802.11 wireless local area network has made it possible for users to connect to Internet almost anywhere. A mobile node (MN) is likely to move between different base stations while running applications. The IETF has defined the Mobile IP (MIP) to allow MNs to maintain their communication uninterrupted while roaming across different IP subnets. However, the mechanisms defined in MIP may cause undesired connection disruptions or packet losses, which will significantly degrade the quality of real‐time applications. It is an important and challenging issue to support seamless handoff management. To achieve seamless handoff, we propose a unified scheme to address application quality degradation. Our main contribution is the concept and implementation of utilising buffering and resending method to eliminate the packet losses while keeping the end‐to‐end delay of real‐time traffic flow in an acceptable value. The NS‐2 simulation results show that our proposed scheme can significantly maintain application quality during layer‐2 and ‐3 handoffs. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
28.
The capability of a cobalt-phosphorous [Co(P)] layer, which was grown via the electroless plating process, to serve as the
diffusion barrier of lead-tin (PbSn) solder was investigated in this work. The Auger electron spectroscopy (AES) and energy
dispersive spectrometry (EDX) indicated that the phosphorous contents in Co(P) films decrease with increasing film thickness
and that the average contents are no less than 8.7 at.% for the specimens prepared in this work. X-ray diffraction in conjunction
with composition analyses revealed that the electroless Co(P) layer was a mixture of amorphous and nanocrystalline structures;
however, the AES depth profile and subsequent analyses indicated that the first-formed Co(P) layer should be amorphous because
it contains as much as 18 at.% P. This implied a good barrier capability for electroless Co(P) because, as revealed by EDX
line scan, the Sn and Cu atoms could not penetrate the Co(P) layer after the PbSn/Cu/Co(P)/Cu/Ti/Si sample was subjected to
annealing at 250°C in a forming gas ambient for 24 h. The fact that Sn and Cu underlayers could not penetrate the Co layer
after such a liquid-state annealing step was evidence that the Co(P) layer may simultaneously serve as a diffusion-barrier
interlayer dielectric and as an under-bump metallization for flip-chip copper (Cu) ICs. 相似文献
29.
Yee-Wen Yen Chun-Yu Lee 《Components and Packaging Technologies, IEEE Transactions on》2008,31(2):399-406
This paper investigates the interconnection between the driver integrated circuit (IC) and glass substrate via anisotropic conductive adhesive (ACF) of chip on glass package. The conductive particle deformation is evaluated using a novel method, optical microscope (OM) inspection. The proposed method is more convenient than the traditional approach using scanning electron microscopy applied in the manufacturing process. Interconnection performance is easily judged using OM, allowing poor interconnection between the driver IC and glass substrate to be screened out. Several types of driver ICs with different bump area ratios (total input bump area/total output bump area, input/output ratio) and length/width (L/W) ratios are designed in this experiment. The conductive particle deformations are investigated in this study. Driver ICs with L/W ratios larger than 15 have better conductive particle deformation uniformity at each position. The average deformation degree at the driver IC center position is larger than that at the side and edge positions. The deformation degree at the input position with a smaller bump area is better than that at the output position. The conductive resistance increases with the reliability testing time because of the thermal stress effect and softening of the ACF polymer material. The deformation degree is related to the conductive resistance of the interconnection. The conductive resistance is lower at the center and input positions with larger deformation degree. 相似文献
30.
Digital rights management system with user privacy,usage transparency,and superdistribution support 下载免费PDF全文
Chih‐Ta Yen Horng‐Twu Liaw Nai‐Wei Lo 《International Journal of Communication Systems》2014,27(10):1714-1730
In the modern world, digital content has been massively produced, distributed, and consumed by human beings; consequently, how to protect the rights and benefits of content consumers, producers, and distributors has become a crucial issue. One promising solution is to design a full‐fledged digital rights management (DRM) system. In this study we introduce a new design on the digital rights management system providing user privacy, usage transparency, and superdistribution. A comprehensive set of DRM processing functions and corresponding mechanisms are developed in our system to support various business process requirements. Superdistribution support is embedded in our system design. A prototype is implemented to verify our system design. To protect consumer privacy, a temporary identity is generated for each consumer using the KryptoKnight protocol. Elliptic curve cryptography‐based encryption scheme is adopted for messages transmitted among servers and client over an unsecure communication channel. For usage transparency, a user‐friendly DRM client package (software) is introduced in the proposed DRM system to achieve content protection and support user convenience in usage.Copyright © 2012 John Wiley & Sons, Ltd. 相似文献