Development of Early Warning System for Public Health Emergencies in China: Focus on SARS, H7N9, COVID-19

ZhenYun Jin(ZhenYun Jin) 충북대학교 국가위기관리연구소 2020 위기관리연구논총 Vol.4 No.1

Confrontation as a Mediator between Sense of Coherence and Self-management Behaviors among Elderly Patients with Coronary Heart Disease in North China

Zhenyun Li,Jing Han,Ting Li,Qina Zhu,Aimin Wang,Ting Liu 한국간호과학회 2017 Asian Nursing Research Vol.11 No.3

Purpose: Self-management is critical to improve health outcomes of elderly patients with coronary heart disease (CHD). Sense of coherence (SOC) is found to be linked with self-management behaviors. However, their deeper relationship is not clear. The purposes of this study were to investigate the association between SOC and self-management behaviors among elderly CHD patients in China, and whether confrontation mediates this association. Methods: A cross-sectional design was used. A total of 275 elderly patients with CHD recruited from the cardiology department in a general hospital in North China were surveyed from October 2015 to April 2016. SOC, confrontation, and self-management behaviors were measured using the Chinese version of the SOC scale, subscale of Medical Coping Modes QuestionnairedConfrontation, and the CHD selfmanagement scale, respectively. Correlation analysis and path analysis were conducted to analyze the data. Results: The mean (±standard deviation) scores of SOC, confrontation, and self-management behaviors were 62.20 (±9.61), 19.55 (±3.15), and 76.17 (±10.63), respectively. Correlation analysis showed that SOC, confrontation, and self-management behaviors were significantly correlated with each other. Path analysis indicated that SOC exerted a direct effect on self-management behaviors, whereas could affect self-management indirectly via confrontation. Bootstrap test result showed that confrontation played a mediating role (b = .20, p < .001) in the relationship between SOC and self-management behaviors. Conclusion: SOC was related to self-management behaviors, whereas confrontation mediated the effect of SOC on self-management behaviors. In practice, the role of confrontation coping should be valued when developing strategies to strengthen SOC and to improve self-management practice among elderly CHD patients.

Performance analyses of antagonistic shape memory alloy actuators based on recovered strain

Zhenyun Shi,Tianmiao Wang,Liu Da 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.14 No.5

In comparison with conventional shape memory actuated structures, antagonistic shape memory alloy (SMA) actuators permits a fully reversible two-way response and higher response frequency. However, excessive internal stress could adversely reduce the stroke of the actuators under repeated use. The two-way shape memory effect might further decrease the range of the recovered strain under actuation of an antagonistic SMA actuator unless additional components (e.g., spring and stopper) are added to regain the overall actuation capability. In this paper, the performance of all four possible types of SMA actuation schemes is investigated in detail with emphasis on five key properties: recovered strain, cyclic degradation, response frequency, self-sensing control accuracy, and controllable maximum output. The testing parameters are chosen based on the maximization of recovered strain. Three types of these actuators are antagonistic SMA actuators, which drive with two active SMA wires in two directions. The antagonistic SMA actuator with an additional pair of springs exhibits wider displacement range, more stable performance under reuse, and faster response, although accurate control cannot be maintained under force interference. With two additional stoppers to prevent the over stretch of the spring, the results showed that the proposed structure could achieve significant improvement on all five properties. It can be concluded that, the last type actuator scheme with additional spring and stopper provide much better applicability than the other three in most conditions. The results of the performance analysis of all four SMA actuators could provide a solid basis for the practical design of SMA actuators.

Performance analyses of antagonistic shape memory alloy actuators based on recovered strain

Shi, Zhenyun,Wang, Tianmiao,Da, Liu Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.14 No.5

In comparison with conventional shape memory actuated structures, antagonistic shape memory alloy (SMA) actuators permits a fully reversible two-way response and higher response frequency. However, excessive internal stress could adversely reduce the stroke of the actuators under repeated use. The two-way shape memory effect might further decrease the range of the recovered strain under actuation of an antagonistic SMA actuator unless additional components (e.g., spring and stopper) are added to regain the overall actuation capability. In this paper, the performance of all four possible types of SMA actuation schemes is investigated in detail with emphasis on five key properties: recovered strain, cyclic degradation, response frequency, self-sensing control accuracy, and controllable maximum output. The testing parameters are chosen based on the maximization of recovered strain. Three types of these actuators are antagonistic SMA actuators, which drive with two active SMA wires in two directions. The antagonistic SMA actuator with an additional pair of springs exhibits wider displacement range, more stable performance under reuse, and faster response, although accurate control cannot be maintained under force interference. With two additional stoppers to prevent the over stretch of the spring, the results showed that the proposed structure could achieve significant improvement on all five properties. It can be concluded that, the last type actuator scheme with additional spring and stopper provide much better applicability than the other three in most conditions. The results of the performance analysis of all four SMA actuators could provide a solid basis for the practical design of SMA actuators.

Wake effects of an upstream bridge on aerodynamic characteristics of a downstream bridge

Zhenhua Chen,Zhenyun Lin,Haojun Tang,Yongle Li,Bin Wang 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.6

To study the wake influence of an upstream bridge on the wind-resistance performance of a downstream bridge, two adjacent long-span cable-stayed bridges are taken as examples. Based on wind tunnel tests, the static aerodynamic coefficients and the dynamic response of the downstream bridge are measured in the wake of the upstream one. Considering different horizontal and vertical distances, the flutter derivatives of the downstream bridge at different angles of attack are extracted by Computational Fluid Dynamics (CFD) simulations and discussed, and the change in critical flutter state is further studied. The results show that a train passing through the downstream bridge could significantly increase the lift coefficient of the bridge which has the same direction with the gravity of the train, leading to possible vertical deformation and vibration. In the wake of the upstream bridge, the change in lift coefficient of the downstream bridge is reduced, but the dynamic response seems to be strong. The effect of aerodynamic interference on flutter stability is related to the horizontal and vertical distances between the two adjacent bridges as well as the attack angle of incoming flow. At large angles of attack, the aerodynamic condition around the downstream girder which may drive the bridge to torsional flutter instability is weakened by the wake of the upstream bridge, and the critical flutter wind speed increases at this situation.

Control strategy for the substructuring testing systems to simulate soil-structure interaction

Jun Guo,Zhenyun Tang,Shicai Chen,Zhenbao Li 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.6

Real-time substructuring techniques are currently an advanced experimental method for testing large size specimens in the laboratory. In dynamic substructuring, the whole tested system is split into two linked parts, the part of particular interest or nonlinearity, which is tested physically, and the remanding part which is tested numerically. To achieve near-perfect synchronization of the interface response between the physical specimen and the numerical model, a good controller is needed to compensate for transfer system dynamics, nonlinearities, uncertainties and time-varying parameters within the physical substructures. This paper presents the substructuring approach and control performance of the linear and the adaptive controllers for testing the dynamic characteristics of soil-structure-interaction system (SSI). This is difficult to emulate as an entire system in the laboratory because of the size and power supply limitations of the experimental facilities. A modified linear substructuring controller (MLSC) is proposed to replace the linear substructuring controller (LSC).The MLSC doesn\'t require the accurate mathematical model of the physical structure that is required by the LSC. The effects of parameter identification errors of physical structure and the shaking table on the control performance of the MLSC are analysed. An adaptive controller was designed to compensate for the errors from the simplification of the physical model in the MLSC, and from parameter identification errors. Comparative simulation and experimental tests were then performed to evaluate the performance of the MLSC and the adaptive controller.

Analysis of Strain Rate Sensitivity and Strain Rate Hardening in Co–Cr–Ni–Mo Wires Drawn with Diff erent Drawing Practices

Sai Srikanth Gvk,M. J. Tan,Zhenyun Liu 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.4

This study investigates the eff ect of strain rate (SR) on the strain rate sensitivity (SRS), strain rate work hardening (SRWH)in Co–35Ni–20Cr–10Mo alloy (MP35N) wires, subjected to drawing practices namely full die drawing (FDD) and half diedrawing (HDD). The experimental results illustrate that the strength, and SRWH, of the drawn wires, increased with therise of SR, whereas the SRS(m) and the ductility decreased with the increase of strain rate (10 −6 s −1 to 10 −2 s −1 ). However,the relative strength, hardening, and the m values were observed to be higher in the FDD drawn wire when compared to theHDD drawn wire. The increase in strength and hardening rate of the FDD drawn wire with the rise in SR was ascribed toincreased dislocation density and reduced twin thickness, and the increased SRS and ductility at low SR were attributed tothe increased grain boundary (GB) activities. The HDD drawn wire had a relatively lower strength, SRWH and SRS rate at anSR of 10 −6 s −1 when compared to other SR, this was attributed to plastic fl ow localization, which led to the formation of shearbands in the material. An abnormal SRWH was observed in the HDD drawn wire tested to an SR of 10 −2 s −1 , where a StageII hardening peak was observed at a very high strain, this was attributed to the solute segregation of the Mo atoms to the GB.