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Distributed Space-Time Block Code over Mixed Rayleigh and Rician Frequency-Selective Fading Channels
Vien, Quoc-Tuan,Tran, Le-Nam,Hong, Een-Kee Hindawi Publishing Corporation 2010 Eurasip Journal on Wireless Communications and Net Vol.2010 No.-
<P>This paper proposes a new distributed space-time block code (DSTBC) over frequency-selective fading channels for two-hop amplify and forward relay networks, consisting of a source node (S), two relay nodes (R1 and R2), and a destination node (D). The proposed DSTBC is designed to achieve maximal spatial diversity gain and decoupling detection of data blocks with a low-complexity receiver. To achieve these two goals, S uses zero-sequence padding, and relay nodes precode the received signals with a proper precoding matrix. The pairwise error probability (PEP) analysis is provided to investigate the achievable diversity gain of the proposed DSTBC for a general channel model in which one hop is modeled by Rayleigh fading and the other by Rician fading. This mixed Rayleigh-Rician channel model allows us to analyze two typical scenarios where {Ri} are in the neighborhood of either S or D.</P>
Network Coding-Based Retransmission for Relay Aided Multisource Multicast Networks
Vien, Quoc-Tuan,Tran, Le-Nam,Hong, Een-Kee Hindawi Publishing Corporation 2011 Eurasip Journal on Wireless Communications and Net Vol.2011 No.-
<P>This paper considers the reliable transmission for wireless multicast networks where multiple sources want to distribute information to a set of destinations with assistance of a relay. Basically, the reliability of a communication link is assured via automatic repeat request (ARQ) protocols. In the context of multisource multicast networks, the challenge is how to retransmit the lost or erroneous packets efficiently. In traditional approaches, the retransmission of lost packets from a single source is treated separately, and thus it may cause a considerable delay. To solve this problem, we propose the relay detects, combines, and forwards the packets which are lost at destinations using network coding. In the proposed ARQ protocol, the relay detects packets from different sources and combines the lost packets using NC. In particular, two packet-combination algorithms are developed to guarantee that all lost packets are retransmitted with the smallest number of retransmissions. Furthermore, we analyze the transmission bandwidth and provide the numerical results to demonstrate the superior performance of the proposed ARQ protocol over some existing schemes.</P>
Vien Cheung,Stephen Westland 한국색채학회 2011 한국색채학회 학술대회 Vol.2011 No.10
Designers who understand colour have greater possibilities at their disposal. This paper discusses four colour-related subjects - colour harmony, colour forecasting, colour preference and colour semiotics - in design; and the way in which their influences may be exploited in the design process. Basic associations of colour are quite clearly understood; thus certain colours (primarily red, but also yellow and orange) are thought of as warm colours whereas other colours (blue and green, for example) are cool colours. These associations can help to construct collections of colours that are harmonious. Colour forecasting aims to evaluate the moods and buying behaviour of consumers 1-2 years in advance and is particularly important in the textile and fashion industries. Many studies have recently considered colour preference in an abstract sense. However, it seems likely that the context in which colour is used in design is also important. There is a need for more colourpreference studies in complex or real environments. Colour semiotics is extremely powerful. However, they are certainly culture-specific, possibly gender, age, and socio-economic specific. Most textbooks provide only a very basic coverage. There is an urgent need for robust and comprehensive studies.
Vien Vo,김희진,김하영,김영미,김성진 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.12
Poly(methacrylic acid)-functionalized SBA-15 silicas (denoted as P-x-PMA/SBA-15 where x is molar ratio of TSPM/(TEOS+TSPM) in percentage in the initial mixture) were synthesized by co-condensation of tetraethoxysilane and varying contents of 3-(trimethoxysilyl)propyl methacrylate in acidic medium with the block copolymer Pluronic 123 as a structure directing agent and then polymerization by methacrylic acid in the presence of ammonium persulfate as an initiator. The functionalized materials were characterized by PXRD, TEM, SEM, IR, and N2 adsorption-desorption at 77 K. The investigation of phenol adsorption in aqueous solution on the materials showed that the poly(methacrylic acid)-functionalized mesoporous silicas possess strong adsorption ability for phenol with interaction of various kinds of hydrogen bonds. The adsorption data were fitted to Langmuir isotherms and the maximum adsorption capacity of the three functionalized materials P-5-PMA/SBA-15, P-10-PMA/SBA-15, and P-15-PMA/SBA-15 to be 129.37 mg/g, 187.97 mg/g, and 78.43 mg/g, respectively, were obtained. The effect of the pH on phenol adsorption was studied.