A kind of novel multi-layer piezoelectric actuator is proposed and integrated with controllable constrained damping treatment to perform hybrid vibration control. The governing equation of the system is derived based ...A kind of novel multi-layer piezoelectric actuator is proposed and integrated with controllable constrained damping treatment to perform hybrid vibration control. The governing equation of the system is derived based on the constitutive equations of elastic, viscoelastic and piezoelectric materials, which shows that the magnitude of control force exerted by multi-layer piezoelectric actuator is the quadratic function of the number of piezoelectric laminates used but in direct proportion to control voltage. This means that the multi-layer actuator can produce greater actuating force than that by piezoelectric laminate actuator with the same area under the identical control voltage. The optimal location placement of the multi-layer piezoelectric actuator is also discussed. As an example, the hybrid vibration control of a cantilever rectangular thin-plate is numerically simulated and carried out experimentally. The simulated and experimental results validate the power of multi-layer piezoelectric actuator and indicate that the present hybrid damping technique can effectively suppress the low frequency modal vibration of the experimental thin-plate structure.展开更多
A nation-wide survey of blood pressure (BP) and high BP was made in China in 1991, using standardized methods and covering 950 356 men and women aged 15 years and above, from 30 provinces, autonomous regions, and muni...A nation-wide survey of blood pressure (BP) and high BP was made in China in 1991, using standardized methods and covering 950 356 men and women aged 15 years and above, from 30 provinces, autonomous regions, and municipalities. The purpose of the study was to estimate the prevalence and the status of awareness, treatment, and control of hypertension. The overall prevalence rate of hypertension defined as systolic BP> 140 or diastolic BP> 90 mmHg or currently on antihypertensive medication was 13.6%, and was higher in urban (16.3%) than in rural (11.1%) setting. The rate was 6.6% if a BP cut-point of 160 / 95 mmHg was used. Rates were low in younger age-groups but rose sharply after age 45. The total number of hypertensives in 1990 was estimated to be close to 90 millions. Of all hypertensives, about 1/4 were aware of their high BP, half of these were on medication, and only 3% had their BP controlled. All the rates were higher if the BP cut-point was 160 / 95 mmHg. Higher rates were found in urban than rural setting and, to a lesser degree, for women than men. In conclusion, hypertension was found to be common in China, and the rates of awareness, drug treatment, and controlled BP were low, indicating an urgent need for developing a national program of treatment and prevention of high BP.展开更多
Objective To investigate gender differences in the risk factors and awareness,treatment,and control of hypertension.Methods The subjects were selected among local residents aged≥18 years old,by multi-stage stratified...Objective To investigate gender differences in the risk factors and awareness,treatment,and control of hypertension.Methods The subjects were selected among local residents aged≥18 years old,by multi-stage stratified-random sampling method.All participants accepted physical examinations including blood tests for lipids,展开更多
In this paper,we propose and analyze a fractional-order SIS epidemic model with the saturated treatment and disease transmission.The existence and uniqueness,nonnegativity and finiteness of solutions for our suggested...In this paper,we propose and analyze a fractional-order SIS epidemic model with the saturated treatment and disease transmission.The existence and uniqueness,nonnegativity and finiteness of solutions for our suggested model have been studied.Different equilibria of the model are found and their local and global stability analyses are also examined.Furthermore,the conditions for fractional backward and fractional Hopf bifurcation are also analyzed in both the commensurate and incommensurate fractional-order model.We study how the control parameter and the order of the fractional derivative play role in local as well as global stability of equilibrium points and Hopf bifurcation.We have demonstrated the analytical results of our proposed model system through several numerical simulations.展开更多
It is essential for cross-regional control and treatment of major epidemics to establish a collaborative,efficient,and precise collective response mechanism.Based on the observation of the COVID-19 epidemic,this paper...It is essential for cross-regional control and treatment of major epidemics to establish a collaborative,efficient,and precise collective response mechanism.Based on the observation of the COVID-19 epidemic,this paper concludes major measures and experience of cross-regional collective response for epidemic control and treatment,compares the difference between localities at home and abroad,and puts forwards major strategies for a cross-regional collective response,hoping to provide policy-making references to improve the modernization level of public health,epidemic prevention,and emergency management in China.展开更多
基金This project is supported by National Natural Science Foundation of China(No.50275114,No.10476020).
文摘A kind of novel multi-layer piezoelectric actuator is proposed and integrated with controllable constrained damping treatment to perform hybrid vibration control. The governing equation of the system is derived based on the constitutive equations of elastic, viscoelastic and piezoelectric materials, which shows that the magnitude of control force exerted by multi-layer piezoelectric actuator is the quadratic function of the number of piezoelectric laminates used but in direct proportion to control voltage. This means that the multi-layer actuator can produce greater actuating force than that by piezoelectric laminate actuator with the same area under the identical control voltage. The optimal location placement of the multi-layer piezoelectric actuator is also discussed. As an example, the hybrid vibration control of a cantilever rectangular thin-plate is numerically simulated and carried out experimentally. The simulated and experimental results validate the power of multi-layer piezoelectric actuator and indicate that the present hybrid damping technique can effectively suppress the low frequency modal vibration of the experimental thin-plate structure.
文摘A nation-wide survey of blood pressure (BP) and high BP was made in China in 1991, using standardized methods and covering 950 356 men and women aged 15 years and above, from 30 provinces, autonomous regions, and municipalities. The purpose of the study was to estimate the prevalence and the status of awareness, treatment, and control of hypertension. The overall prevalence rate of hypertension defined as systolic BP> 140 or diastolic BP> 90 mmHg or currently on antihypertensive medication was 13.6%, and was higher in urban (16.3%) than in rural (11.1%) setting. The rate was 6.6% if a BP cut-point of 160 / 95 mmHg was used. Rates were low in younger age-groups but rose sharply after age 45. The total number of hypertensives in 1990 was estimated to be close to 90 millions. Of all hypertensives, about 1/4 were aware of their high BP, half of these were on medication, and only 3% had their BP controlled. All the rates were higher if the BP cut-point was 160 / 95 mmHg. Higher rates were found in urban than rural setting and, to a lesser degree, for women than men. In conclusion, hypertension was found to be common in China, and the rates of awareness, drug treatment, and controlled BP were low, indicating an urgent need for developing a national program of treatment and prevention of high BP.
文摘Objective To investigate gender differences in the risk factors and awareness,treatment,and control of hypertension.Methods The subjects were selected among local residents aged≥18 years old,by multi-stage stratified-random sampling method.All participants accepted physical examinations including blood tests for lipids,
基金The work of S.J.is financially supported by the Department of Science&Technology and Biotechnology,Government of West Bengal(vide memo no.201(Sanc.)/ST/P/S&T/16G-12/2018 dt 19-02-2019)。
文摘In this paper,we propose and analyze a fractional-order SIS epidemic model with the saturated treatment and disease transmission.The existence and uniqueness,nonnegativity and finiteness of solutions for our suggested model have been studied.Different equilibria of the model are found and their local and global stability analyses are also examined.Furthermore,the conditions for fractional backward and fractional Hopf bifurcation are also analyzed in both the commensurate and incommensurate fractional-order model.We study how the control parameter and the order of the fractional derivative play role in local as well as global stability of equilibrium points and Hopf bifurcation.We have demonstrated the analytical results of our proposed model system through several numerical simulations.
文摘It is essential for cross-regional control and treatment of major epidemics to establish a collaborative,efficient,and precise collective response mechanism.Based on the observation of the COVID-19 epidemic,this paper concludes major measures and experience of cross-regional collective response for epidemic control and treatment,compares the difference between localities at home and abroad,and puts forwards major strategies for a cross-regional collective response,hoping to provide policy-making references to improve the modernization level of public health,epidemic prevention,and emergency management in China.
