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Zhengqiu Zhang,Zheng Zhou 대한수학회 2011 대한수학회지 Vol.48 No.2
In this paper, the problem on periodic solutions of the bidi-rectional associative memory neural networks with both periodic coef-cients and periodic time-varying delays is discussed. By using degree theory, inequality technique and Lyapunov functional, we establish the existence, uniqueness, and global asymptotic stability of a periodic solu-tion. The obtained results of stability are less restrictive than previously known criteria, and the hypotheses for the boundedness and monotonicity on the activation functions are removed.
Zhang, Zhengqiu,Zhou, Zheng Korean Mathematical Society 2011 대한수학회지 Vol.48 No.2
In this paper, the problem on periodic solutions of the bidirectional associative memory neural networks with both periodic coefficients and periodic time-varying delays is discussed. By using degree theory, inequality technique and Lyapunov functional, we establish the existence, uniqueness, and global asymptotic stability of a periodic solution. The obtained results of stability are less restrictive than previously known criteria, and the hypotheses for the boundedness and monotonicity on the activation functions are removed.
Zhang, Zhengqiu,Wang, Liping Korean Mathematical Society 2011 대한수학회지 Vol.48 No.4
By employing coincidence degree theory and using Halanay-type inequality technique, a sufficient condition is given to guarantee the existence and global exponential stability of periodic solutions for the two-dimensional discrete-time Cohen-Grossberg BAM neural networks. Compared with the results in existing papers, in our result on the existence of periodic solution, the boundedness conditions on the activation are replaced with global Lipschitz conditions. In our result on the existence and global exponential stability of periodic solution, the assumptions in existing papers that the value of activation functions at zero is zero are removed.
Zhengqiu Zhang,Liping Wang 대한수학회 2011 대한수학회지 Vol.48 No.4
By employing coincidence degree theory and using Halanay-type inequality technique, a sufficient condition is given to guarantee the existence and global exponential stability of periodic solutions for the two-dimensional discrete-time Cohen-Grossberg BAM neural networks. Compared with the results in existing papers, in our result on the exis-tence of periodic solution, the boundedness conditions on the activation are replaced with global Lipschitz conditions. In our result on the exis-tence and global exponential stability of periodic solution, the assump-tions in existing papers that the value of activation functions at zero is zero are removed.
Zhengqiu Zhang,Zhicheng Wang 대한수학회 2003 대한수학회지 Vol.40 No.5
In this paper, a nonautonomous predator-preydispersion delay models with functional response is studied. Byusing the continuation theorem of coincidence degree theory,the existence of a positive periodic solution for above modelsis established.
Zhang, Zhengqiu,Wang, Zhicheng Korean Mathematical Society 2003 대한수학회지 Vol.40 No.5
In this paper, a nonautonomous predator-prey dispersion delay models with functional response is studied. By using the continuation theorem of coincidence degree theory, the existence of a positive periodic solution for above models is established.
Zhengqiu Zhu,Lingshan Chen,Wenjun Liu,Yiyun Wu,Chong Zou,Xinyi Zhang,Shanshan He,Yinping Wang,Bixiao Shen,Xuehui Ma,Hui Gao,Yun Luan,Hui Huang 대한초음파의학회 2022 ULTRASONOGRAPHY Vol.41 No.3
Purpose: The present study investigated the association between Systematic COronary Risk Evaluation (SCORE)-estimated cardiovascular risk and carotid stiffening in a middle-aged population using ultrafast pulse wave velocity (ufPWV).Methods: This study enrolled 683 participants without known cardiovascular disease or diabetes mellitus who underwent ufPWV measurements. Clinical interviews, physical examinations, laboratory findings, carotid intima-media thickness (cIMT), pulse wave velocity (PWV) at the beginning of systole (PWV-BS), and PWV at the end of systole (PWV-ES) were assessed. Each participant underwent an assessment of SCORE risk based on major cardiovascular risk factors (CVRFs), including age, sex, smoking, systolic blood pressure (SBP), and total cholesterol (TC). Crude and adjusted odds ratios (ORs) with 95% confidence intervals and ordinal logistic regression were used. Overall CVRFs were adjusted to assess ORs.Results: cIMT and carotid stiffening in PWV-BS and PWV-ES were significantly different between sex subgroups (all P<0.05), but only PWV-ES increased gradually in age and SCORE-estimated risk subgroups (all P<0.05). Compared with cIMT (r=0.388, P<0.001) and PWV-BS (r=0.159, P<0.001), PWV-ES was more strongly correlated with SCORE categories (r=0.405, P<0.001). Higher PWV-ES values were associated with SCORE categories independently of sex, SBP, TC, and smoking in moderate-risk and high-risk subgroups (OR, 1.63; P<0.001 and OR, 2.12; P=0.024, respectively), but were not independent of age in all risk subgroups (all P>0.05).Conclusion: Carotid stiffening quantified by ufPWV is linked to SCORE categories, and elevated PWV-ES may aid in cardiovascular risk stratification.