Kun-Feng Zhang
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Kun-Feng Zhang has a total of 10 co-authors. Here are the top co-authors by number of shared publications:
- Gang Tian
Massachusetts Institute of Technology
1 shared publication Jiao Yang
1 shared publicationXiao-Lei Shan
Department of Clinical Pharmacology, China Medical University, Shenyang, Liaoning 110001, People's Republic of China
1 shared publication- Xiaohua Zhu
School of Mathematical Sciences and BICMR, Peking University, Beijing, China
1 shared publication Xue-Ying Zhou
1 shared publicationYan-Li Wang
1 shared publication
Latest Publications
- Open Access
- 1 January 2017
- Published by Wiley in Mathematical Problems in Engineering
- Vol. 2017 (1)
A Parameter Estimation Algorithm for Multiple Frequency‐Hopping Signals Based on Sparse Bayesian Method
Parameter estimation and network sorting for noncooperative wideband frequency‐hopping (FH) signals have been essential and challenging tasks, especially in the case with little or even no prior information at all. In this paper, we propose a nearly blind estimation approach to estimate signal parameters based on sparse Bayesian reconstruction. Taking the sparsity in the spatial frequency domain of multiple FH signals into account, we propose a sparse Bayesian algorithm to estimate the spatial frequency parameters. As a result, the frequency and direction of arrival (DOA) parameters can be obtained. In order to improve the accuracy of the estimation parameters, we employ morphological filter methods to further clean the data poisoned by the noise. Moreover, our method is applicable to the wideband signal models with little prior information. We also conduct extensive numerical simulations to verify the performance of our method. Notably, the proposed method works well even in low signal‐to‐noise ratio (SNR) environment.
- 1 January 2017
- Published by Wiley in Mathematical Problems in Engineering
- Vol. 2017 (1)
Open AccessA Parameter Estimation Algorithm for Multiple Frequency‐Hopping Signals Based on Sparse Bayesian Method
Parameter estimation and network sorting for noncooperative wideband frequency‐hopping (FH) signals have been essential and challenging tasks, especially in the case with little or even no prior information at all. In this paper, we propose a nearly blind estimation approach to estimate signal parameters based on sparse Bayesian reconstruction. Taking the sparsity in the spatial frequency domain of multiple FH signals into account, we propose a sparse Bayesian algorithm to estimate the spatial frequency parameters. As a result, the frequency and direction of arrival (DOA) parameters can be obtained. In order to improve the accuracy of the estimation parameters, we employ morphological filter methods to further clean the data poisoned by the noise. Moreover, our method is applicable to the wideband signal models with little prior information. We also conduct extensive numerical simulations to verify the performance of our method. Notably, the proposed method works well even in low signal‐to‐noise ratio (SNR) environment.
- Open Access
On a sharp volume estimate for gradient Ricci solitons with scalar curvature bounded below
In this note, we obtain a sharp volume estimate for complete gradient Ricci solitons with scalar curvature bounded below by a positive constant. Using Chen-Yokota's argument we obtain a local lower bound estimate of the scalar curvature for the Ricci flow on complete manifolds. Consequently, one has a sharp estimate of the scalar curvature for expanding Ricci solitons; we also provide a direct (elliptic) proof of this sharp estimate. Moreover, if the scalar curvature attains its minimum value at some point, then the manifold is Einstein.
Open AccessOn a sharp volume estimate for gradient Ricci solitons with scalar curvature bounded below
In this note, we obtain a sharp volume estimate for complete gradient Ricci solitons with scalar curvature bounded below by a positive constant. Using Chen-Yokota's argument we obtain a local lower bound estimate of the scalar curvature for the Ricci flow on complete manifolds. Consequently, one has a sharp estimate of the scalar curvature for expanding Ricci solitons; we also provide a direct (elliptic) proof of this sharp estimate. Moreover, if the scalar curvature attains its minimum value at some point, then the manifold is Einstein.
- Open Access
Supremum of Perelman's entropy and Kähler-Ricci flow on a Fano manifold
In this paper, we extend the method in [TZhu5] to study the energy level $L(\cdot)$ of Perelman's entropy $\lambda(\cdot)$ for K\"ahler-Ricci flow on a Fano manifold. Consequently, we first compute the supremum of $\lambda(\cdot)$ in K\"ahler class $2\pi c_1(M)$ under an assumption that the modified Mabuchi's K-energy $\mu(\cdot)$ defined in [TZhu2] is bounded from below. Secondly, we give an alternative proof to the main theorem about the convergence of K\"ahler-Ricci flow in [TZhu3].Open AccessSupremum of Perelman's entropy and Kähler-Ricci flow on a Fano manifold
In this paper, we extend the method in [TZhu5] to study the energy level $L(\cdot)$ of Perelman's entropy $\lambda(\cdot)$ for K\"ahler-Ricci flow on a Fano manifold. Consequently, we first compute the supremum of $\lambda(\cdot)$ in K\"ahler class $2\pi c_1(M)$ under an assumption that the modified Mabuchi's K-energy $\mu(\cdot)$ defined in [TZhu2] is bounded from below. Secondly, we give an alternative proof to the main theorem about the convergence of K\"ahler-Ricci flow in [TZhu3]. - 5 January 2010
- Published by Editorial Office of Chinese Journal of Cancer in Chinese Journal of Cancer
- Vol. 29 (1) , 20-23
Inhibitory effect of cucurbitacin E on the proliferation of ovarian cancer cells and its mechanism
There are various biological activities of cucurbitacin E (CuE), including antitumor effect, anti-chemical carcino-genesis, liver protection, and enhancement of the immunity, and so on. This study was to investigate the effect of CuE on proliferation inhibition and apoptosis induction of ovarian cancer ES-2 cells, and to explore the mechanism. ES-2 cells were treated with different concentrations of CuE for 24, 48, and 72 h, respectively. Cell proliferation was tested by MTT assay. The morphologic changes and apoptosis were observed under inverted microscope and fluorescent microscope. Cell cycle distribution was evaluated with flow cytometry. The expression of p-STAT3 was determined by Western blot. The number of ES-2 significantly decreased as the concentration of CuE increased or the time prolonged. Flow cytometry analysis showed that the ratio of ES-2 cells treated 1 micromol/L CuE for 24 h increased both in S phase [from (10.55+/-0.91)% to ( 16.31 +/- 4.61) % ] and in G(2)/M phase [from (18.53+/-1.43)% to (58.34 +/- 5.77)%], while decreased in G(1) phase [from (73.13 +/-4.70)% to (23.12 +/- 5.45)%] (P<0.05). The marked morphological changes of cell apoptosis were clearly observed in ES-2 cells treated with CuE. CuE inhibited the STAT3 phosphorylation in ES-2 cell in a dose- dependent manner. CuE can inhibit ES-2 proliferation and induce apoptosis and cell cycle arrest, which may be related to the decreased expression of the intracellular STAT3 phosphorylation.
- 5 January 2010
- Published by Editorial Office of Chinese Journal of Cancer in Chinese Journal of Cancer
- Vol. 29 (1) , 20-23
Inhibitory effect of cucurbitacin E on the proliferation of ovarian cancer cells and its mechanism
There are various biological activities of cucurbitacin E (CuE), including antitumor effect, anti-chemical carcino-genesis, liver protection, and enhancement of the immunity, and so on. This study was to investigate the effect of CuE on proliferation inhibition and apoptosis induction of ovarian cancer ES-2 cells, and to explore the mechanism. ES-2 cells were treated with different concentrations of CuE for 24, 48, and 72 h, respectively. Cell proliferation was tested by MTT assay. The morphologic changes and apoptosis were observed under inverted microscope and fluorescent microscope. Cell cycle distribution was evaluated with flow cytometry. The expression of p-STAT3 was determined by Western blot. The number of ES-2 significantly decreased as the concentration of CuE increased or the time prolonged. Flow cytometry analysis showed that the ratio of ES-2 cells treated 1 micromol/L CuE for 24 h increased both in S phase [from (10.55+/-0.91)% to ( 16.31 +/- 4.61) % ] and in G(2)/M phase [from (18.53+/-1.43)% to (58.34 +/- 5.77)%], while decreased in G(1) phase [from (73.13 +/-4.70)% to (23.12 +/- 5.45)%] (P<0.05). The marked morphological changes of cell apoptosis were clearly observed in ES-2 cells treated with CuE. CuE inhibited the STAT3 phosphorylation in ES-2 cell in a dose- dependent manner. CuE can inhibit ES-2 proliferation and induce apoptosis and cell cycle arrest, which may be related to the decreased expression of the intracellular STAT3 phosphorylation.