With the extensive application of large-scale array antennas,the increasing number of array elements leads to the increasing dimension of received signals,making it difficult to meet the real-time requirement of direc...With the extensive application of large-scale array antennas,the increasing number of array elements leads to the increasing dimension of received signals,making it difficult to meet the real-time requirement of direction of arrival(DOA)estimation due to the computational complexity of algorithms.Traditional subspace algorithms require estimation of the covariance matrix,which has high computational complexity and is prone to producing spurious peaks.In order to reduce the computational complexity of DOA estimation algorithms and improve their estimation accuracy under large array elements,this paper proposes a DOA estimation method based on Krylov subspace and weighted l_(1)-norm.The method uses the multistage Wiener filter(MSWF)iteration to solve the basis of the Krylov subspace as an estimate of the signal subspace,further uses the measurement matrix to reduce the dimensionality of the signal subspace observation,constructs a weighted matrix,and combines the sparse reconstruction to establish a convex optimization function based on the residual sum of squares and weighted l_(1)-norm to solve the target DOA.Simulation results show that the proposed method has high resolution under large array conditions,effectively suppresses spurious peaks,reduces computational complexity,and has good robustness for low signal to noise ratio(SNR)environment.展开更多
The property awc1 was used by many authors to obtain results concerning approximation by elements of weak Chebyshev subspaces. In this paper the author studies this property in details, by collecting the scattered res...The property awc1 was used by many authors to obtain results concerning approximation by elements of weak Chebyshev subspaces. In this paper the author studies this property in details, by collecting the scattered results concerning it and by finding new ones.展开更多
Some new characterizations and immediate explicit expressions of best L(1≤p≤∞) approximation and their deviations by an n-dimensional subspace on a set of n+1 points are given.
In 1965 Gohler introduced 2-normed spaces and since then, this topic have been intensively studied and developed. We shall introduce the notion of 1-type proximinal subspaces of 2-normed spaces and give some results i...In 1965 Gohler introduced 2-normed spaces and since then, this topic have been intensively studied and developed. We shall introduce the notion of 1-type proximinal subspaces of 2-normed spaces and give some results in this field.展开更多
In this paper, we construct some 1 1/2-designs, which are also known as partial geometric designs, using totally isotropic subspaces of the symplectic space and generalized symplectic graphs. Furthermore, these 1^-des...In this paper, we construct some 1 1/2-designs, which are also known as partial geometric designs, using totally isotropic subspaces of the symplectic space and generalized symplectic graphs. Furthermore, these 1^-designs yield six infinite families of directed strongly regular graphs.展开更多
The HIV-1 gp120 exterior envelope glycoprotein undergoes a series of conformational rearrangements while sequentially interacting with the receptor CD4 and coreceptor CCR5 or CXCR4 on the surface of host cells to init...The HIV-1 gp120 exterior envelope glycoprotein undergoes a series of conformational rearrangements while sequentially interacting with the receptor CD4 and coreceptor CCR5 or CXCR4 on the surface of host cells to initiate virus entry. Both the crystal structures of the HIV-1 gp120 core bound by the CD4 and antigen 17b and the SIV gp120 core pre-bound by CD4 are known. Despite the wealth of knowledge on these static snapshots of molecular conformations,the details of molecular motions involved in conformational transition that are crucial to intervention remain elusive. We presented comprehensive comparative analyses of the dynamics behaviors of the gp120 in its CD4-complexed,CD4-free and CD4-unliganded states based on the homology models with modeled V3 and V4 loops by means of CONCOORD computer simulation to generate ensembles of feasible protein structures that were sub-sequently analysed by essential dynamics analyses to identify preferred concerted motions. The re-vealed collective fluctuations are dominated by complex modes of combinational motions of the rota-tion/twisting,flexing/closure,and shortness/elongation between or within the inner,outer,and bridg-ing-sheet domains,and these modes are related to the CD4 association and HIV neutralization avoid-ance. Further essential subspace overlap analyses were performed to quantitatively distinguish the preference for conformational transitions between the three states,revealing that the unliganded gp120 has a greater potential to translate its conformation into the conformational state adopted by the CD4-complexed gp120 than by the CD4-free gp120,whereas the CD4-free gp120 has a greater potential to translate its conformation into the unliganded state than the CD4-complexed gp120 does. These dynamics data of gp120 in its different conformations are helpful in understanding the relationship between the molecular motion/conformational transition and the function of gp120,and in gp120-structure-based subunit vaccine design.展开更多
In this paper, we construct some 1（1/2）-designs, which are also known as partial geometric designs, using totally isotropic subspaces of the unitary space. Phrthermore, these 1（1/2）-designs yield six infinite fami...In this paper, we construct some 1（1/2）-designs, which are also known as partial geometric designs, using totally isotropic subspaces of the unitary space. Phrthermore, these 1（1/2）-designs yield six infinite families of directed strongly regular graphs.展开更多
基金supported by the National Basic Research Program of China。
文摘With the extensive application of large-scale array antennas,the increasing number of array elements leads to the increasing dimension of received signals,making it difficult to meet the real-time requirement of direction of arrival(DOA)estimation due to the computational complexity of algorithms.Traditional subspace algorithms require estimation of the covariance matrix,which has high computational complexity and is prone to producing spurious peaks.In order to reduce the computational complexity of DOA estimation algorithms and improve their estimation accuracy under large array elements,this paper proposes a DOA estimation method based on Krylov subspace and weighted l_(1)-norm.The method uses the multistage Wiener filter(MSWF)iteration to solve the basis of the Krylov subspace as an estimate of the signal subspace,further uses the measurement matrix to reduce the dimensionality of the signal subspace observation,constructs a weighted matrix,and combines the sparse reconstruction to establish a convex optimization function based on the residual sum of squares and weighted l_(1)-norm to solve the target DOA.Simulation results show that the proposed method has high resolution under large array conditions,effectively suppresses spurious peaks,reduces computational complexity,and has good robustness for low signal to noise ratio(SNR)environment.
文摘The property awc1 was used by many authors to obtain results concerning approximation by elements of weak Chebyshev subspaces. In this paper the author studies this property in details, by collecting the scattered results concerning it and by finding new ones.
文摘Some new characterizations and immediate explicit expressions of best L(1≤p≤∞) approximation and their deviations by an n-dimensional subspace on a set of n+1 points are given.
文摘In 1965 Gohler introduced 2-normed spaces and since then, this topic have been intensively studied and developed. We shall introduce the notion of 1-type proximinal subspaces of 2-normed spaces and give some results in this field.
基金Supported by National Natural Science Foundation of China(Grant No.61370187)
文摘In this paper, we construct some 1 1/2-designs, which are also known as partial geometric designs, using totally isotropic subspaces of the symplectic space and generalized symplectic graphs. Furthermore, these 1^-designs yield six infinite families of directed strongly regular graphs.
基金Supported by the Yunnan University (Grant No. 2004Q013B)Yunnan Province (Grant No. 2006C008M)partially supported by open fund from the Laboratory for Conservation and Utilization of Bio-resources, Yunnan University, and Innova-tion Group Project from Yunnan University
文摘The HIV-1 gp120 exterior envelope glycoprotein undergoes a series of conformational rearrangements while sequentially interacting with the receptor CD4 and coreceptor CCR5 or CXCR4 on the surface of host cells to initiate virus entry. Both the crystal structures of the HIV-1 gp120 core bound by the CD4 and antigen 17b and the SIV gp120 core pre-bound by CD4 are known. Despite the wealth of knowledge on these static snapshots of molecular conformations,the details of molecular motions involved in conformational transition that are crucial to intervention remain elusive. We presented comprehensive comparative analyses of the dynamics behaviors of the gp120 in its CD4-complexed,CD4-free and CD4-unliganded states based on the homology models with modeled V3 and V4 loops by means of CONCOORD computer simulation to generate ensembles of feasible protein structures that were sub-sequently analysed by essential dynamics analyses to identify preferred concerted motions. The re-vealed collective fluctuations are dominated by complex modes of combinational motions of the rota-tion/twisting,flexing/closure,and shortness/elongation between or within the inner,outer,and bridg-ing-sheet domains,and these modes are related to the CD4 association and HIV neutralization avoid-ance. Further essential subspace overlap analyses were performed to quantitatively distinguish the preference for conformational transitions between the three states,revealing that the unliganded gp120 has a greater potential to translate its conformation into the conformational state adopted by the CD4-complexed gp120 than by the CD4-free gp120,whereas the CD4-free gp120 has a greater potential to translate its conformation into the unliganded state than the CD4-complexed gp120 does. These dynamics data of gp120 in its different conformations are helpful in understanding the relationship between the molecular motion/conformational transition and the function of gp120,and in gp120-structure-based subunit vaccine design.
文摘In this paper, we construct some 1（1/2）-designs, which are also known as partial geometric designs, using totally isotropic subspaces of the unitary space. Phrthermore, these 1（1/2）-designs yield six infinite families of directed strongly regular graphs.
