Control of sound transmission into a large composite cylinder using passive, adaptive–passive and active control strategies

2003 ◽  
Vol 114 (4) ◽  
pp. 2390-2391
Author(s):  
Marty Johnson ◽  
Simon Esteve ◽  
Chris Fuller
2010 ◽  
Vol 128 (4) ◽  
pp. 2436-2436
Author(s):  
Guoyong Jin ◽  
Shuangxia Shi ◽  
Zhigang Liu

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 378
Author(s):  
Irene Salinas ◽  
Juan José Hueso ◽  
Julián Cuevas

Papaya is a tropical fruit crop that in subtropical regions depends on protected cultivation to fulfill its climate requirements and remain productive. The aim of this work was to compare the profitability of different climate control strategies in greenhouses located in subtropical areas of southeast Spain. To do so, we compared papayas growing in a greenhouse equipped with active climate control (ACC), achieved by cooling and heating systems, versus plants growing in another greenhouse equipped with passive climate control (PCC), consisting of only natural ventilation through zenithal and lateral windows. The results showed that ACC favored papaya plant growth; flowering; fruit set; and, consequently, yields, producing more and heavier fruits at an affordable cost. Climate control strategies did not significantly improve fruit quality, specifically fruit skin color, acidity, and total soluble solids content. In conclusion, in the current context of prices, an active control of temperature and humidity inside the greenhouse could be a more profitable strategy in subtropical regions where open-air cultivation is not feasible.


2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Wander Gustavo Rocha Vieira ◽  
Fred Nitzsche ◽  
Carlos De Marqui

In recent decades, semi-active control strategies have been investigated for vibration reduction. In general, these techniques provide enhanced control performance when compared to traditional passive techniques and lower energy consumption if compared to active control techniques. In semi-active concepts, vibration attenuation is achieved by modulating inertial, stiffness, or damping properties of a dynamic system. The smart spring is a mechanical device originally employed for the effective modulation of its stiffness through the use of semi-active control strategies. This device has been successfully tested to damp aeroelastic oscillations of fixed and rotary wings. In this paper, the modeling of the smart spring mechanism is presented and two semi-active control algorithms are employed to promote vibration reduction through enhanced damping effects. The first control technique is the smart-spring resetting (SSR), which resembles resetting control techniques developed for vibration reduction of civil structures as well as the piezoelectric synchronized switch damping on short (SSDS) technique. The second control algorithm is referred to as the smart-spring inversion (SSI), which presents some similarities with the synchronized switch damping (SSD) on inductor technique previously presented in the literature of electromechanically coupled systems. The effects of the SSR and SSI control algorithms on the free and forced responses of the smart-spring are investigated in time and frequency domains. An energy flow analysis is also presented in order to explain the enhanced damping behavior when the SSI control algorithm is employed.


2009 ◽  
Vol 59 (3) ◽  
pp. 433-453 ◽  
Author(s):  
Xiao-min Dong ◽  
Miao Yu ◽  
Chang-rong Liao ◽  
Wei-min Chen

Author(s):  
Alessia Ussia ◽  
Alessio Bonelli ◽  
Oreste S. Bursi

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