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Search Results: 1 - 10 of 80771 matches for " LIANG Yu "
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A New Transmission Control Protocol for Satellite Networks  [PDF]
Liang Yu, Gang Zhou
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2011, DOI: 10.4236/ijcns.2011.44031
Abstract: According to technical statistics, current TCP protocols with approximately 80% Internet applications run on perform very well on wired networks. However, due to the effects of long propagation delay, great bandwidth asymmetry, high sporadic Bit Error Rate (BER) and etc., TCP performance degrades obviously on the satellite communication networks. To avoid the problems, TP-S, a novel transport control protocol, is introduced for satellite IP networks. Firstly, in order to increase the increment speed of Congestion Window (cwnd) at the beginning of data transmission, the traditional Slow Start strategy is replaced by a new strategy, known as Super Start. Secondly, a new packet lost discriminated scheme based on IP packets alternately sending with different priority is used in the protocol to decouple congestion decision from errors. Thirdly, bandwidth asymmetry problem is avoided by adopting Modified NACK (M-NACK) in receiving ends, which is sent periodically. In addition, the sending strategy in routers is also modified along with other’s changes to support the protocol. Finally, the simulation experiments show that the new protocol can not only significantly enhance throughput performance, but also reduce sharply bandwidth used in the reverse path as compared with traditional TCP protocols and those protocols, which are recently proposed for satellite IP networks.
An expression meta-analysis of predicted microRNA targets identifies a diagnostic signature for lung cancer
Yu Liang
BMC Medical Genomics , 2008, DOI: 10.1186/1755-8794-1-61
Abstract: MiRNA target genes were predicted by union of miRanda, TargetScan, and PicTar, followed by screening for matched gene symbols in NCBI human sequences and Gene Ontology (GO) terms using the PANTHER database that was also used for analyzing the significance of biological processes and pathways within each ontology term. Microarray data were extracted from Gene Expression Omnibus repository, and tumor subtype prediction by gene expression used Prediction Analysis of Microarrays.Computationally predicted target genes of three microRNAs, miR-34b/34c/449, that were detected in human lung, testis, and fallopian tubes but not in other normal tissues, were filtered by representation of GO terms and their ability to classify lung cancer subtypes, followed by a meta-analysis of microarray data to classify AD and SCC. Expression of a minimal set of 17 predicted miR-34b/34c/449 target genes derived from the developmental process GO category was identified from a training set to classify 41 AD and 17 SCC, and correctly predicted in average 87% of 354 AD and 82% of 282 SCC specimens from total 9 independent published datasets. The accuracy of prediction still remains comparable when classifying 103 AD and 79 SCC samples from another 4 published datasets that have only 14 to 16 of the 17 genes available for prediction (84% and 85% for AD and SCC, respectively). Expression of this signature in two published datasets of epithelial cells obtained at bronchoscopy from cigarette smokers, if combined with cytopathology of the cells, yielded 89–90% sensitivity of lung cancer detection and 87–90% negative predictive value to non-cancer patients.This study focuses on predicted targets of three lung-enriched miRNAs, compares their expression patterns in lung cancer by their GO terms, and identifies a minimal set of genes differentially expressed in AD and SCC, followed by validating this gene signature in multiple published datasets. Expression of this gene signature in bronchial epithelial
Asymptotic Limits of the Wigner $12J$-Symbol in Terms of the Ponzano-Regge Phases
Liang Yu
Physics , 2011,
Abstract: There are two types of asymptotic formulas for the $12j$ symbol with one small and 11 large angular momenta. We have derived the first type of formula previously in [L. Yu, Phys. Rev. A84 022101 (2011)]. We will derive the second type in this paper. We find that this second asymptotic formula for the $12j$ symbol is expressed in terms of the vector diagram associated with two $6j$ symbols, namely, the vector diagram of two adjacent tetrahedra sharing a common face. As a result, two sets of Ponzano-Regge phases appear in the asymptotic formula. This work contributes another asymptotic formula of the Wigner $12j$ symbol to the re-coupling theory of angular momenta.
Semiclassical Analysis of the Wigner $12j$ Symbol with One Small Angular Momentum
Liang Yu
Physics , 2011, DOI: 10.1103/PhysRevA.84.022101
Abstract: We derive an asymptotic formula for the Wigner $12j$ symbol, in the limit of one small and 11 large angular momenta. There are two kinds of asymptotic formulas for the $12j$ symbol with one small angular momentum. We present the first kind of formula in this paper. Our derivation relies on the techniques developed in the semiclassical analysis of the Wigner $9j$ symbol [L. Yu and R. G. Littlejohn, Phys. Rev. A 83, 052114 (2011)], where we used a gauge-invariant form of the multicomponent WKB wave-functions to derive asymptotic formulas for the $9j$ symbol with small and large angular momenta. When applying the same technique to the $12j$ symbol in this paper, we find that the spinor is diagonalized in the direction of an intermediate angular momentum. In addition, we find that the geometry of the derived asymptotic formula for the $12j$ symbol is expressed in terms of the vector diagram for a $9j$ symbol. This illustrates a general geometric connection between asymptotic limits of the various $3nj$ symbols. This work contributes the first known asymptotic formula for the $12j$ symbol to the quantum theory of angular momentum, and serves as a basis for finding asymptotic formulas for the Wigner $15j$ symbol with two small angular momenta.
Asymptotic Limits of the Wigner $15J$-Symbol with Small Quantum Numbers
Liang Yu
Physics , 2011,
Abstract: We present new asymptotic formulas for the Wigner $15j$-symbol with two, three, or four small quantum numbers, and provide numerical evidence of their validity. These formulas are of the WKB form and are of a similar nature as the Ponzano-Regge formula for the Wigner $6j$-symbol. They are expressed in terms of edge lengths and angles of geometrical figures associated with angular momentum vectors. In particular, the formulas for the $15j$-symbol with two, three, and four small quantum numbers are based on the geometric figures of the $9j$-, $6j$-, and $3j$-symbols, respectively, The geometric nature of these new asymptotic formulas pave the way for further analysis of the semiclassical limits of vertex amplitudes in loop quantum gravity models.
Asymptotic Analysis of the Wigner $3j$-Symbol in the Bargmann Representation
Liang Yu
Physics , 2011,
Abstract: We derive the leading asymptotic limit of the Wigner $3j$-symbol from a stationary phase approximation of a twelve dimensional integral, obtained from an inner product between two exact Bargmann wavefunctions. We show that, by the construction of the Bargmann inner product, the stationary phase conditions have a geometric description in terms of the Hopf fibration of ${\mathbb C}^6$ into ${\mathbb R}^3 \times {\mathbb R}^3 \times {\mathbb R}^3$. In addition, we find that, except for the usual modification of the quantum numbers by 1/2, the imaginary part of the logarithm of a Bargmann wavefunction, evaluated at the stationary points, is equal to the asymptotic phase of the $3j$-symbol.
Uniform Approximation from Symbol Calculus on a Spherical Phase Space
Liang Yu
Mathematics , 2011, DOI: 10.1088/1751-8113/44/50/505202
Abstract: We use symbol correspondence and quantum normal form theory to develop a more general method for finding uniform asymptotic approximations. We then apply this method to derive a result we announced in an earlier paper, namely, the uniform approximation of the $6j$-symbol in terms of the rotation matrices. The derivation is based on the Stratonovich-Weyl symbol correspondence between matrix operators and functions on a spherical phase space. The resulting approximation depends on a canonical, or area preserving, map between two pairs of intersecting level sets on the spherical phase space.
On the existence of natural self-oscillation of a free electron
Zhixian Yu,Liang Yu
Physics , 2012,
Abstract: The possibility of the existence of natural self-oscillation of a free electron is suggested. This oscillation depends on the interaction of the electron with its own electromagnetic fields. Suitable standing wave solutions of the electromagnetic fields are chosen. A kind of displacement dependent electric potential and mechanism of energy exchange between velocity and acceleration dependent electromagnetic fields are analyzed. Conditions for the existence of natural self-oscillation are given.
Displacement induced electric force and natural self-oscillation of a free electron
Zhixian Yu,Liang Yu
Physics , 2013,
Abstract: We show that a kind of displacement induced temporary electric force of a single point charge can be derived by using Maxwell stress analysis. This force comes from the variation of the charge's electric intensities that follow Coulomb's inverse square law, and it is a kind of displacement dependent temporary restoring force. We also show the possible existence of natural self-oscillation of a free electron which is driven by this restoring self-force of its own electric fields.
An Improved Task Scheduling Algorithm in Grid Computing Environment  [PDF]
Liang Yu, Gang Zhou, Yifei Pu
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2011, DOI: 10.4236/ijcns.2011.44027
Abstract: Algorithm research of task scheduling is one of the key techniques in grid computing. This paper firstly describes a DAG task scheduling model used in grid computing environment, secondly discusses generational scheduling (GS) and communication inclusion generational scheduling (CIGS) algorithms. Finally, an improved CIGS algorithm is proposed to use in grid computing environment, and it has been proved effectively.
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