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Search Results: 1 - 10 of 37980 matches for " Hai-Tao Xia "
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Deterministic Constructions of Binary Measurement Matrices from Finite Geometry
Shu-Tao Xia,Xin-Ji Liu,Yong Jiang,Hai-Tao Zheng
Mathematics , 2013,
Abstract: Deterministic constructions of measurement matrices in compressed sensing (CS) are considered in this paper. The constructions are inspired by the recent discovery of Dimakis, Smarandache and Vontobel which says that parity-check matrices of good low-density parity-check (LDPC) codes can be used as {provably} good measurement matrices for compressed sensing under $\ell_1$-minimization. The performance of the proposed binary measurement matrices is mainly theoretically analyzed with the help of the analyzing methods and results from (finite geometry) LDPC codes. Particularly, several lower bounds of the spark (i.e., the smallest number of columns that are linearly dependent, which totally characterizes the recovery performance of $\ell_0$-minimization) of general binary matrices and finite geometry matrices are obtained and they improve the previously known results in most cases. Simulation results show that the proposed matrices perform comparably to, sometimes even better than, the corresponding Gaussian random matrices. Moreover, the proposed matrices are sparse, binary, and most of them have cyclic or quasi-cyclic structure, which will make the hardware realization convenient and easy.
Maximum Multiflow in Wireless Network Coding
Jin-Yi Zhou,Shu-Tao Xia,Yong Jiang,Hai-Tao Zheng
Mathematics , 2012,
Abstract: In a multihop wireless network, wireless interference is crucial to the maximum multiflow (MMF) problem, which studies the maximum throughput between multiple pairs of sources and sinks. In this paper, we observe that network coding could help to decrease the impacts of wireless interference, and propose a framework to study the MMF problem for multihop wireless networks with network coding. Firstly, a network model is set up to describe the new conflict relations modified by network coding. Then, we formulate a linear programming problem to compute the maximum throughput and show its superiority over one in networks without coding. Finally, the MMF problem in wireless network coding is shown to be NP-hard and a polynomial approximation algorithm is proposed.
Diaquabis(N,N′-dibenzylethane-1,2-diamine-κ2N,N′)nickel(II) dichloride N,N-dimethylformamide solvate
Yu-Fen Liu,Hai-Tao Xia,Da-Qi Wang,Xiao-Lin Gong
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809046042
Abstract: The asymmetric unit of the title complex, [Ni(C16H20N2)2(H2O)2]Cl2·C3H7NO, consists of two NiII atoms, each lying on an inversion center, two Cl anions, two N,N′-dibenzylethane-1,2-diamine ligands, two coordinated water molecules and one N,N-dimethylformamide solvent molecule. Each NiII atom is six-coordinated in a distorted octahedral coordination geometry, with the equatorial plane formed by four N atoms and the axial positions occupied by two water molecules. The complex molecules are linked into a chain along [001] by N—H...Cl, N—H...O and O—H...Cl hydrogen bonds. The C atoms and H atoms of the solvent molecule are disordered over two sites in a ratio of 0.52 (2):0.48 (2).
Di-μ-chlorido-bis[chlorido(N,N′-dibenzylpropane-1,2-diamine-κ2N,N′)copper(II)]
Yu-Fen Liu,Da-Fu Rong,Hai-Tao Xia,Da-Qi Wang
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809044997
Abstract: In the title complex, [Cu2Cl4(C17H22N2)2], the CuII cation is coordinated by a N,N′-dibenzylpropane-1,2-diamine ligand and two Cl anions, and a Cl anion from an adjacent molecule further bridges to the CuII cation in the apical position, with a longer Cu—Cl distance of 2.9858 (18) , forming a centrosymmetric dimeric complex in which each CuII cation is in a distorted square-pyramidal geometry. Intramolecular N—H...Cl hydrogen bonding is observed in the dimeric complex.
Tetrakis(μ-naphthalene-1-acetato-1:2κ2O:O′)bis(naphthalene-1-acetato)-1κ2O,O′;2κ2O,O′-bis(1,10-phenanthroline)-1κ2N,N′;2κ2N,N′-europium(III)samarium(III)
Hai-Tao Xia,Yu-Fen Liu,Liang Chen,Da-Qi Wang
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808032960
Abstract: In the title compound, [EuSm(C12H9O2)6(C12H8N2)2], the metal site is statistically occupied (50:50) by Eu and Sm atoms, forming a centrosymmetric complex. The metal site is nine-coordinate, in a distorted monocapped square-antiprismatic coordination geometry. Molecules are linked into three chains by C—H...π interactions and C—H...O hydrogen bonds. The combination of these chains generates a three-dimensional framework structure. One of the bridging naphthalene-1-acetate ligands was found to be disordered over two sites; the site occupancies for the naphthylmethyl group refined to 0.628 (14) and 0.372 (14).
Bis{6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(iminomethylene)]diphenolato(1.5 )-κ4O,N,N′,O′}erbium(III)
Hai-Tao Xia,De-Fu Rong,Ying-Ying Zhang,Shu-Ping Yang
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809001421
Abstract: In the title compound, [Er(C18H22.5N2O4)2], the Er atom is located on a twofold rotation axis and is eight-coordinated by four O atoms and four N atoms from two symmetry-related 6,6′-dimethoxy-2,2′-(ethane-1,2-diyldiiminodimethylene)diphenolate(1.5 ) ligands. Due to disorder of one phenolate H atom with half-occupation, the overall charge of one tetradentate ligand is 1.5. The ligand molecules are stabilised by intramolecular N—H...O and O—H...O hydrogen bonds and are linked into a chain parallel to the a axis by a C—H...O hydrogen bond. Neighbouring chains are connected by van der Waals forces, resulting in a three-dimensional network.
Bis{6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(iminomethylene)]diphenolato(1.5 )-κ4O,N,N′,O′}praeseodymium(III)
Hai-Tao Xia,Yu-Fen Liu,Shu-Ping Yang,Da-Qi Wang
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809001500
Abstract: The title compound, [Pr(C18H22.5N2O4)2], is isotypic with its Er and Tb analogues. All interatomic distances, angles and the hydrogen bond geometry are very similar for the three structures..
Poly[(N,N-dimethylformamide-κO)tris(μ-naphthalene-1-acetato)terbium(III)]
Hai-Tao Xia,Yu-Fen Liu,Ying-Ying Zhang,Da-Qi Wang
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808036155
Abstract: In title compound, [Tb(C12H9O2)3(C3H7NO)]n, the Tb atom is nine-coordinated by nine O atoms from three naphthalene-1-acetate and one N,N-dimethylformamide ligands. The Tb atoms are linked by three bridging naphthalene-1-acetate ligands into a chain parallel to the b axis. Further stabilization of the structure is accomplished by non-classical C—H...O hydrogen bonds and C—H...π interactions.
Bis{6,6′-dimethoxy-2,2′-[ethane-1,2-diylbis(iminomethylene)]diphenolato(1.5 )-κ4O,N,N′,O′}terbium(III)
Hai-Tao Xia,Yu-Fen Liu,Shu-Ping Yang,Da-Qi Wang
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809001494
Abstract: The title compound, [Tb(C18H22.5N2O4)2], is isotypic with its Pr and Tb analogues. All interatomic distances, angles and the hydrogen bond geometry are very similar for the three structures.
[N,N′-Bis(4-chlorobenzyl)ethane-1,2-diamine]dichloridozinc(II)
Shu-Ping Yang,Li-Jun Han,Da-Qi Wang,Hai-Tao Xia
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536807063088
Abstract: In the title complex, [ZnCl2(C16H18Cl2N2)], the asymmetric unit contains one molecule and two half-molecules, which have similar geometric parameters; in the latter two molecules each Zn atom lies on a twofold rotation axis. The environment about each ZnII atom is distorted tetrahedral with coordination of two terminal Cl atoms and two N atoms of the N,N′-bis(4-chlorobenzyl)ethane-1,2-diamine ligand. Four N—H...Cl hydrogen bonds link the molecules into a chain of R22(8) rings in the [001] direction.
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