oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 47 )

2018 ( 460 )

2017 ( 449 )

2016 ( 431 )

Custom range...

Search Results: 1 - 10 of 24947 matches for " Lei Cao "
All listed articles are free for downloading (OA Articles)
Page 1 /24947
Display every page Item
The Empirical Research of Factors Influencing Share of Wallet in the B2B Market  [PDF]
Aiwu Cheng, Lei Han, Cheng Cao
Journal of Service Science and Management (JSSM) , 2011, DOI: 10.4236/jssm.2011.42020
Abstract: Share of wallet is a key factor in Customer relationship management system (CRM) which is an important application of E-business. Research has found that share of wallet is an important indicator to measure customer loyalty and cus-tomer potential value. On the basis of the existent marketing literatures, this study analyzes the variables influencing share of wallet according the traits of the B2B market. This paper brings forward interrelated hypotheses and concep-tual model,then test the hypotheses with enterprises survey in the B2B market. Finally we use path analysis to find the principal factors influencing share of wallet and the relationships in them. The results of this research provide theo-retical foundation to upgrade CRM management level of the B2B enterprises, and there is a certain reference value to predict share of wallet in customer lifetime value’s (CLV) measurement.
Linkability of Convertible Undeniable Partially Blind Signature Scheme
Hong Lei,Tianjie Cao
Asian Journal of Information Technology , 2012,
Abstract: Blind signature allows a user to obtain signatures from an authority on any document, in such a way that the authority learns nothing about the message that is being signed. In partially blind signatures, the signer can explicitly include some agreed common information such as the expiration date and the face value in the blind signature. The blindness is an important property in blind signature scheme. In this work, we analyze security of Huang et al s convertible undeniable partially blind signature scheme and show that the scheme doesn t satisfy blindness, in other words, the signer is able to link a valid message-signature pair obtained by some user. It means that the blind signature scheme is not secure.
Joint Decoding of Concatenated VLEC and STTC System
Chen Huijun,Cao Lei
EURASIP Journal on Wireless Communications and Networking , 2008,
Abstract: We consider the decoding of wireless communication systems with both source coding in the application layer and channel coding in the physical layer for high-performance transmission over fading channels. Variable length error correcting codes (VLECs) and space time trellis codes (STTCs) are used to provide bandwidth efficient data compression as well as coding and diversity gains. At the receiver, an iterative joint source and space time decoding scheme are developed to utilize redundancy in both STTC and VLEC to improve overall decoding performance. Issues such as the inseparable systematic information in the symbol level, the asymmetric trellis structure of VLEC, and information exchange between bit and symbol domains have been considered in the maximum a posteriori probability (MAP) decoding algorithm. Simulation results indicate that the developed joint decoding scheme achieves a significant decoding gain over the separate decoding in fading channels, whether or not the channel information is perfectly known at the receiver. Furthermore, how rate allocation between STTC and VLEC affects the performance of the joint source and space-time decoder is investigated. Different systems with a fixed overall information rate are studied. It is shown that for a system with more redundancy dedicated to the source code and a higher order modulation of STTC, the joint decoding yields better performance, though with increased complexity.
Differential Detection of Space-Time Spreading with Two Transmit Antennas
Shi Tao,Cao Lei
EURASIP Journal on Wireless Communications and Networking , 2006,
Abstract: A differential detection scheme for space-time spreading with two transmit antennas is proposed. The scheme does not require channel state information at either the transmitter or the receiver. With segmentation and preamble symbols padded at the transmitter, the receiver recovers the information using differential detection. Both phase-shift keying (PSK) and quadrature amplitude modulation (QAM) signals are considered. The proposed scheme achieves two-level transmit diversity gain with low complexity and saves the use of channel estimation, while having about 3 dB performance loss as compared to the coherent detection scheme. When multiple receive antennas exist, additional receive diversity gain can be achieved along with the transmit diversity gain. The scheme works fine under block-fading channel as well as slow Rayleigh fading channel, which is a popular scenario for high-rate data communications. The system performance for different segment sizes, channel fading speeds, modulation methods, and numbers of receive antennas is studied through simulations.
Joint Decoding of Concatenated VLEC and STTC System
Huijun Chen,Lei Cao
EURASIP Journal on Wireless Communications and Networking , 2008, DOI: 10.1155/2008/890194
Abstract: We consider the decoding of wireless communication systems with both source coding in the application layer and channel coding in the physical layer for high-performance transmission over fading channels. Variable length error correcting codes (VLECs) and space time trellis codes (STTCs) are used to provide bandwidth efficient data compression as well as coding and diversity gains. At the receiver, an iterative joint source and space time decoding scheme are developed to utilize redundancy in both STTC and VLEC to improve overall decoding performance. Issues such as the inseparable systematic information in the symbol level, the asymmetric trellis structure of VLEC, and information exchange between bit and symbol domains have been considered in the maximum a posteriori probability (MAP) decoding algorithm. Simulation results indicate that the developed joint decoding scheme achieves a significant decoding gain over the separate decoding in fading channels, whether or not the channel information is perfectly known at the receiver. Furthermore, how rate allocation between STTC and VLEC affects the performance of the joint source and space-time decoder is investigated. Different systems with a fixed overall information rate are studied. It is shown that for a system with more redundancy dedicated to the source code and a higher order modulation of STTC, the joint decoding yields better performance, though with increased complexity.
Differential Detection of Space-Time Spreading with Two Transmit Antennas
Tao Shi,Lei Cao
EURASIP Journal on Wireless Communications and Networking , 2006,
Abstract: A differential detection scheme for space-time spreading with two transmit antennas is proposed. The scheme does not require channel state information at either the transmitter or the receiver. With segmentation and preamble symbols padded at the transmitter, the receiver recovers the information using differential detection. Both phase-shift keying (PSK) and quadrature amplitude modulation (QAM) signals are considered. The proposed scheme achieves two-level transmit diversity gain with low complexity and saves the use of channel estimation, while having about 3 dB performance loss as compared to the coherent detection scheme. When multiple receive antennas exist, additional receive diversity gain can be achieved along with the transmit diversity gain. The scheme works fine under block-fading channel as well as slow Rayleigh fading channel, which is a popular scenario for high-rate data communications. The system performance for different segment sizes, channel fading speeds, modulation methods, and numbers of receive antennas is studied through simulations.
Turn-Directed α-β Conformational Transition of α-syn12 Peptide at Different pH Revealed by Unbiased Molecular Dynamics Simulations
Lei Liu,Zanxia Cao
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms140610896
Abstract: The transition from α-helical to β-hairpin conformations of α-syn12 peptide is characterized here using long timescale, unbiased molecular dynamics (MD) simulations in explicit solvent models at physiological and acidic pH values. Four independent normal MD trajectories, each 2500 ns, are performed at 300 K using the GROMOS 43A1 force field and SPC water model. The most clustered structures at both pH values are β-hairpin but with different turns and hydrogen bonds. Turn 9-6 and four hydrogen bonds (HB 9-6, HB 6-9, HB 11-4 and HB 4-11) are formed at physiological pH; turn 8-5 and five hydrogen bonds (HB 8-5, HB 5-8, HB 10-3, HB 3-10 and HB 12-1) are formed at acidic pH. A common folding mechanism is observed: the formation of the turn is always before the formation of the hydrogen bonds, which means the turn is always found to be the major determinant in initiating the transition process. Furthermore, two transition paths are observed at physiological pH. One of the transition paths tends to form the most-clustered turn and improper hydrogen bonds at the beginning, and then form the most-clustered hydrogen bonds. Another transition path tends to form the most-clustered turn, and turn 5-2 firstly, followed by the formation of part hydrogen bonds, then turn 5-2 is extended and more hydrogen bonds are formed. The transition path at acidic pH is as the same as the first path described at physiological pH.
On Exponential Sums, Nowton identities and Dickson Polynomials over Finite Fields
Xiwang Cao,Lei Hu
Mathematics , 2010,
Abstract: Let $\mathbb{F}_{q}$ be a finite field, $\mathbb{F}_{q^s}$ be an extension of $\mathbb{F}_q$, let $f(x)\in \mathbb{F}_q[x]$ be a polynomial of degree $n$ with $\gcd(n,q)=1$. We present a recursive formula for evaluating the exponential sum $\sum_{c\in \mathbb{F}_{q^s}}\chi^{(s)}(f(x))$. Let $a$ and $b$ be two elements in $\mathbb{F}_q$ with $a\neq 0$, $u$ be a positive integer. We obtain an estimate for the exponential sum $\sum_{c\in \mathbb{F}^*_{q^s}}\chi^{(s)}(ac^u+bc^{-1})$, where $\chi^{(s)}$ is the lifting of an additive character $\chi$ of $\mathbb{F}_q$. Some properties of the sequences constructed from these exponential sums are provided also.
On Exponential Sums, Nowton identities and Dickson Polynomials over Finite Fields
Xiwang Cao,Lei Hu
Mathematics , 2010,
Abstract: Let $\mathbb{F}_{q}$ be a finite field, $\mathbb{F}_{q^s}$ be an extension of $\mathbb{F}_q$, let $f(x)\in \mathbb{F}_q[x]$ be a polynomial of degree $n$ with $\gcd(n,q)=1$. We present a recursive formula for evaluating the exponential sum $\sum_{c\in \mathbb{F}_{q^s}}\chi^{(s)}(f(x))$. Let $a$ and $b$ be two elements in $\mathbb{F}_q$ with $a\neq 0$, $u$ be a positive integer. We obtain an estimate for the exponential sum $\sum_{c\in \mathbb{F}^*_{q^s}}\chi^{(s)}(ac^u+bc^{-1})$, where $\chi^{(s)}$ is the lifting of an additive character $\chi$ of $\mathbb{F}_q$. Some properties of the sequences constructed from these exponential sums are provided also.
Two Boolean functions with five-valued Walsh spectra and high nonlinearity
Xiwang Cao,Lei Hu
Mathematics , 2014,
Abstract: For cryptographic systems the method of confusion and diffusion is used as a fundamental technique to achieve security. Confusion is reflected in nonlinearity of certain Boolean functions describing the cryptographic transformation. In this paper, we present two balanced boolean functions which have low Walsh spectra and high nonlinearity. In the proof of the nonlinearity, a new method for evaluating some exponential sums over finite fields was provided.
Page 1 /24947
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.