ANALYSIS OF A DELAY PREY-PREDATOR MODEL WITH DISEASE IN THE PREY SPECIES ONLY

Zhou, Xueyong,Shi, Xiangyun,Song, Xinyu Korean Mathematical Society 2009 대한수학회지 Vol.46 No.4

In this paper, a three-dimensional eco-epidemiological model with delay is considered. The stability of the two equilibria, the existence of Hopf bifurcation and the permanence are investigated. It is found that Hopf bifurcation occurs when the delay ${\tau}$ passes though a sequence of critical values. The estimation of the length of delay to preserve stability has also been calculated. Numerical simulation with a hypothetical set of data has been done to support the analytical findings.

Negative sequence control for DC voltage balancing in three‑phase cascaded H‑bridge rectifiers considering DC‑port failures

Xinyu Zhu,Xiao Liang,Kaiyue Gong,Xu Peng,Jun Cai,Xiaohan Liu,Chao Zhou,Siqi An,Chao Wu,Pengcheng Han 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.12

As a vital component of power electronic transformers (PET), the reliability of a cascaded H-bridge rectifier (CHBR) is essential. Therefore, in this paper, a DC-port voltage balance strategy considering DC-port failure is researched to ensure the stable operation of a CHBR. However, if the DC-port voltage balance strategy is adopted to realize the single-phase balance of a CHBR, the three-phase currents become unbalanced. This paper uses a negative sequence control (NSC) strategy that is conducive to balancing DC-port voltage to achieve three-phase current balance. For the DC-port voltage balance, the matrix generation modulation (MGM) algorithm is proposed. In addition, the DC-port voltage balance boundary is analyzed to determine the range of the DC-port voltage balance in the CHBR. A 3-module cascading topology is adopted to demonstrate the MGM algorithm and the NSC strategy. Through experiments, results show the correctness and feasibility of the proposed strategy.

Structure and electrical properties of Bi0.5(Na, K)0.5TiO3-BiGaO3 lead-free piezoelectric ceramics

Changrong Zhou,Xinyu Liu,Weizhou Li,Changlai Yuan,Guohua Chen 한국물리학회 2010 Current Applied Physics Vol.10 No.1

Lead-free piezoelectric ceramics (1 - x - y)Bi0.5Na0.5TiO3-xBi0.5K0.5TiO3- yBiGaO3 have been fabricated by an ordinary sintering technique, and their structure and electrical properties and depolarization temperature have been studied. The results of X-ray diffraction reveal that Bi0.5K0.5TiO3 and BiGaO3 diffuse into the Bi0.5Na0.5TiO3 lattices to form a new solid solution with a pure perovskite structure. An obvious change in microstructure with increasing concentration of Bi0.5K0.5TiO3 and BiGaO3 was observed. The piezoelectric constant d33 and the electromechanical coupling factor kp of the ceramics attain maximum values of 165 pC/N and 0.346 at y = 0.01(x = 0.18) and x = 0.21(y = 0.01), respectively. The temperature dependence of dielectric constant indicates an obvious relaxor characteristic with strong frequency dependence of dielectric constant. The depolarization temperature decreased with increasing content of BiGaO3 and first decreases and then increases with increasing amount of Bi0.5K0.5TiO3.

Analysis of a delay prey-predator model with disease in the prey species only

Xueyong Zhou,Xiangyun Shi,Xinyu Song 대한수학회 2009 대한수학회지 Vol.46 No.4

In this paper, a three-dimensional eco-epidemiological model with delay is considered. The stability of the two equilibria, the existence of Hopf bifurcation and the permanence are investigated. It is found that Hopf bifurcation occurs when the delay τ passes though a sequence of critical values. The estimation of the length of delay to preserve stability has also been calculated. Numerical simulation with a hypothetical set of data has been done to support the analytical findings. In this paper, a three-dimensional eco-epidemiological model with delay is considered. The stability of the two equilibria, the existence of Hopf bifurcation and the permanence are investigated. It is found that Hopf bifurcation occurs when the delay τ passes though a sequence of critical values. The estimation of the length of delay to preserve stability has also been calculated. Numerical simulation with a hypothetical set of data has been done to support the analytical findings.

Robust and Fast Tracking via Joint Collaborative Representation

Fei Zhou,Guizong Zhang,Xinyue Fan,Dandan Yi 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.4

In this paper, we present a robust and fast tracking method based on joint collaborative representation. Traditional sparse coding based tracking methods code the candidates as a sparse linear combination of a series of object and trivial templates and perform time consuming L1 regularizations. In contrast to these methods, this paper adopts the L2-regularized least square models to reduce the computational complexity. The tracked object can be represented by the linear combination of a series of object templates, and also can be represented by candidate samples in the current frame. We propose a joint objective function to handle the tracking process. In addition, we introduce an effective update scheme to deal with the change of target appearance over time. Experiments on several challenging image sequences show that our proposed tracking method is robust and efficient.

PERIODIC SOLUTIONS FOR DISCRETE ONE-PREDATOR TWO-PREY SYSTEM WITH THE MODIFIED LESLIE-GOWER FUNCTIONAL RESPONSE

Shi, Xiangyun,Zhou, Xueyong,Song, Xinyu The Korean Society for Computational and Applied M 2009 Journal of applied mathematics & informatics Vol.27 No.3

In this paper, we study a discrete Leslie-Gower one-predator two-prey model. By using the method of coincidence degree and some techniques, we obtain the existence of at least one positive periodic solution of the system. By linalization of the model at positive periodic solution and construction of Lyapunov function, sufficient conditions are obtained to ensure the global stability of the positive periodic solution. Numerical simulations are carried out to explain the analytical findings.

Study on bond behavior of steel reinforced high strength concrete after high temperatures

Chen, Zongping,Zhou, Ji,Wang, Xinyue Techno-Press 2020 Advances in concrete construction Vol.10 No.2

This paper presents experimental results on bond-slip behavior of steel reinforced high-strength concrete (SRHC) after exposure to elevated temperatures. Three parameters were considered in this test: (a) high temperatures (i.e., 20℃, 200℃, 400℃, 600℃, 800℃); (b) concrete strength (i.e., C60, C70, C80); (c) anchorage length (i.e., 250 mm, 400 mm). A total of 17 SRHC specimens subjected to high temperatures were designed for push out test. The load-slip curves at the loading end and free end were obtained, the influence of various variation parameters on the ultimate bond strength and residual bond strength was analyzed, in addition, the influence of elevated temperatures on the invalidation mechanism was researched in details. Test results show that the shapes of load-slip curves at loading ends and free ends are similar. The ultimate bond strength and residual bond strength of SRHC decrease first and then recover partly with the temperature increasing. The bond strength is proportional to the concrete strength, and the bond strength is proportional to the anchoring length when the temperature is low, while the opposite situation occurs when the temperature is high. What's more, the bond damage of specimens with lower temperature develops earlier and faster than the specimens with higher temperature. From these experimental findings, the bond-slip constitutive formula of SRHC subjected to elevated temperatures is proposed, which fills well with test data.

Durably Superhydrophobic Cotton Fabric Constructed by Silica Particles and Polydimethylsiloxane via “Mosaic Mode” for Self-Cleaning and Oil–Water Separation

Qingbo Xu,Xinyu Wang,Jing Zhou,Peng Wang,Yanyan Zhang,Qian Chen 한국섬유공학회 2023 Fibers and polymers Vol.24 No.1

Improving the surface roughness of cotton fabric is one of the main strategies to prepare superhydrophobic cotton fabric. To improve the surface roughness of fabric, it is advisable to immobilize inorganic/organic particles on the surface of cottonfabric. However, the durability of the superhydrophobic cotton fabric is very poor due to the inorganic/organic particlesare easily detachable from the fabric surface. In this work, a mild eutectic solvent prepared by choline chloride and oxalicacid was used to etch the cotton fabric, making the surface of the cotton fabric have many ravines. These ravines on the cottonfabric can be used the embedded the silica particles, thus making the silica particles firmly immobilized on the cottonfibers. Then, the treated cotton fabric was coated with polydimethylsiloxane (PDMS). As a result, the water contact angleof the finished fabric was reached at 156.9°. In addition, the superhydrophobic cotton fabric constructed by silica particlesand PDMS via “Mosaic Mode” showed excellent mechanical and chemical stability. Therefore, the finished fabric has greatpotential application in the self-cleaning and oil–water separation fields.

Dynamic analysis of a cylindrical boom based on Miura origami

Jianguo Cai,Ya Zhou,Xinyu Wang,Yixiang Xu,Jian Feng 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.5

The dynamic behavior of the deployment and folding process of a foldable boom based on the Miura origami pattern is investigated in this paper. Firstly, mechanical behavior of a single storey during the motion is studied numerically. Then the deployment and folding of a multi-storey boom is discussed. Moreover, the influence of the geometry parameters and the number of Miura-ori elements n on the dynamic behavior of the boom is also studied. Finally, the influence of the imperfection on the dynamic behavior is investigated. The results show that the angles between the diagonal folds and horizontal folds will have great effect on the strains during the motion. A bistable configuration can be obtained by choosing proper fold angles for a given multi-storey boom. The influence of the imperfection on the folding behavior of the foldable mast is significant.

Passivity-based Finite-time Bounded Stabilization of Nonlinear Singularly Perturbed Systems with Time Delays: An Iterative Solving Algorithm

Shuhan Wang,Sai Zhou,Jun Song,Xinyu Lv,Yugang Niu 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.11

A finite-time passive controller is developed in this paper for Lipschitz nonlinear systems subject to singular perturbation, time-delays, and parameter uncertainties. Based on the singular perturbation theory and passive control theory, a robust passive controller is drafted for the finite-time interval though the unknown and bounded exogenous disturbances. Some sufficient conditions are obtained for the existence of finite-time robust passive controller, which ensures the resulting closed-loop system is finite-time bounded for all allowable uncertainties. A simulation example is provided to illustrate the validity of the proposed controller.