The Effects of Forced Vibration on the Motion of a Large Bubble Under Microgravity

2021 ◽  
Vol 33 (5) ◽  
Author(s):  
M. Kawaji ◽  
D. Lyubimov ◽  
N. Ichikawa ◽  
T. Lyubimova ◽  
A. Kariyasaki ◽  
...  
1989 ◽  
Vol 21 (6-7) ◽  
pp. 669-676
Author(s):  
E. Davis

The Lagoon method of waste water treatment was introduced into Canada in the mid 1950's. At present, of the 2019 waste water treatment systems in Canada, 1163 are Lagoon systems and 265 of these include aeration equipment. Continuing difficulties associated with the plugging of the aerators have led to a study of this maintenance problem. Physical factors have been identified as the major cause of the plugging of large bubble aerators; whereas chemical solution and deposition under high algal growth conditions have been set forward as the causes of fine bubble aerator plugging. Selected field investigation data collected indicate that the proposed push-pull system of precipitation of calcium carbonate and silica dioxide may in fact be responsible for the plugging of fine bubble aerators with these materials.


2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Trung Thanh Tran ◽  
Van Ke Tran ◽  
Pham Binh Le ◽  
Van Minh Phung ◽  
Van Thom Do ◽  
...  

This paper carries out forced vibration analysis of graphene nanoplatelet-reinforced composite laminated shells in thermal environments by employing the finite element method (FEM). Material properties including elastic modulus, specific gravity, and Poisson’s ratio are determined according to the Halpin–Tsai model. The first-order shear deformation theory (FSDT), which is based on the 8-node isoparametric element to establish the oscillation equation of shell structure, is employed in this work. We then code the computing program in the MATLAB application and examine the verification of convergence rate and reliability of the program by comparing the data of present work with those of other exact solutions. The effects of both geometric parameters and mechanical properties of materials on the forced vibration of the structure are investigated.


Author(s):  
Dalong Tian ◽  
Jianguo Guo

This study aims to develop an advanced integral terminal sliding-mode robust control method using a disturbance observer (DO) to suppress the forced vibration of a large space intelligent truss structure (LSITS). First, the dynamics of the electromechanical coupling of the piezoelectric stack actuator and the LSITS, based on finite element and Lagrangian methods, are established. Subsequently, to constrict the vibration of the structure, a novel integral terminal sliding-mode control (ITSMC) law for the DO is used to estimate the parameter perturbation of the LSITS based on a continuous external disturbance. Simulation results show that, under a forced vibration and compared with the ITSMC system without a DO, the displacement amplitude of the ITSMC system with the DO is effectively reduced. In the case where the model parameters of the LSITS deviate by ±50%, and an unknown continuous external disturbance exists, the control system with the DO can adequately attenuate the structural vibration and realize robust control. Concurrently, the voltage of the employed piezoelectric stack actuator is reduced, and voltage jitter is alleviated.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hiroto Nakajima ◽  
Atsushi Miyashita ◽  
Hiroshi Hamamoto ◽  
Kazuhisa Sekimizu

AbstractIn this study, we investigated a new application of bubble-eye goldfish (commercially available strain with large bubble-shaped eye sacs) for immunological studies in fishes utilizing the technical advantage of examining immune cells in the eye sac fluid ex vivo without sacrificing animals. As known in many aquatic species, the common goldfish strain showed an increased infection sensitivity at elevated temperature, which we demonstrate may be due to an immune impairment using the bubble-eye goldfish model. Injection of heat-killed bacterial cells into the eye sac resulted in an inflammatory symptom (surface reddening) and increased gene expression of pro-inflammatory cytokines observed in vivo, and elevated rearing temperature suppressed the induction of pro-inflammatory gene expressions. We further conducted ex vivo experiments using the immune cells harvested from the eye sac and found that the induced expression of pro-inflammatory cytokines was suppressed when we increased the temperature of ex vivo culture, suggesting that the temperature response of the eye-sac immune cells is a cell autonomous function. These results indicate that the bubble-eye goldfish is a suitable model for ex vivo investigation of fish immune cells and that the temperature-induced infection susceptibility in the goldfish may be due to functional impairments of immune cells.


1968 ◽  
Vol 11 (5) ◽  
pp. 0731-0735 ◽  
Author(s):  
W. R. DeTar ◽  
C. G. Haugh and J. F. Hamilton

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