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Friction ◽  
2021 ◽  
Author(s):  
Shuangxi Tang ◽  
Shayu Li ◽  
Liran Ma ◽  
Yu Tian

AbstractFluid viscosity is ubiquitous property and is of practical importance in intelligent fluids, industrial lubrication, and pipeline fluid transportation. Recently, there has been a surging interest in viscosity regulation. Here, we have developed a group of photorheological fluids by utilizing azobenzene polymers with a light-induced microstructure transformation. In this work, a photosensitive polymer with 4,4′-bis-hydroxyazobenzene as the main chain was designed and synthesized as a pivotal functional material. The sufficiently large structural difference under ultraviolet and near-infrared light makes it possible to regulate the viscosity of a polyethylene glycol solution. The viscosity of the photosensitive rheological fluids under ultraviolet light radiation is found to be up to 45.1% higher than that under near-infrared light radiation. To explore this intelligent lubricating technology, the friction regulation of ceramic sliding bearings was investigated utilizing photosensitive rheological fluids. Reversible friction regulation with a ratio of up to 3.77 has been achieved by the alternative irradiation of near-infrared and ultraviolet light, which can be attributed to the differences in mechanical properties and molecular structures under ultraviolet and near-infrared light according to both simulations and experiments. Such photorheological fluids will have promising applications in controllable lubrication, intelligent rheological fluids, and photosensitive dampers.


2021 ◽  
Author(s):  
Yanan Li ◽  
Yi'chun Cui ◽  
Zefeng Guo ◽  
Hua Guan ◽  
Lu Gao

2021 ◽  
Vol 52 ◽  
pp. 184-191
Author(s):  
Ana Reyes Pérez ◽  
Teresa Espejo Arias ◽  
María Rosario Blanc García ◽  
Amparo Escolano ◽  
Nuria Gómez Hernández

2021 ◽  
Vol 2091 (1) ◽  
pp. 012072
Author(s):  
P Korolenko ◽  
R Kubanov ◽  
N Pavlov ◽  
A Zotov

Abstract A brief retrospective analysis of studies of fractal light radiation is carried out. To assess the prospects of this scientific direction, new original results of studying the diffraction propagation of vortex wave beams with a fractal structure (vortex diffractals) are also presented. For this purpose, computational algorithms and related software have been developed. In calculating the amplitude-phase and scaling characteristics of diffractals two-dimensional Weierstrass functions and multistructures of Gaussian beams were used. The results indicate a high information capacity of vortex diffractals and explain their resistance to the influence of turbulence in the propagation medium.


2021 ◽  
Author(s):  
Liuye Yao ◽  
Zhiyu Qian ◽  
Lu Zhou ◽  
Yu Zhang ◽  
Yangyang Liu ◽  
...  

2021 ◽  
Vol 43 (10) ◽  
Author(s):  
Tong Zhu ◽  
Jinghui Yang ◽  
Di Zhang ◽  
Qinqin Cai ◽  
Yi Shen ◽  
...  
Keyword(s):  

Author(s):  
Hamidreza Masjedi ◽  
Hamed Zamani ◽  
Saman Dalvand ◽  
Mohammad Hossein Zare

Introduction: Generally, the benefits of radiological examinations performed on individuals far outweigh their risks; however, this is not true when the radiographic system fails to work properly. Therefore, to avoid such errors, it is crucial to frequently perform Quality Control (QC) checks in an imaging facility. Material and Methods: A total of 11 highly-referred centers out of 62 radiology rooms located in Yazd province were included in this investigation, and QC tests comprising light/radiation field alignment, the accuracy of kilovoltage and exposure time, reproducibility of kilovoltage, exposure time, and output, and linearity of output against exposure time and milliamperage were performed for each equipment. The light and radiation field alignment test were carried out by a quantitative assessment of digital images of a collimator template (PTW-Freiburg, Germany). The measurements were made by a Barracuda package and a Multi-Purpose Detector (MPD). Results: In terms of the light/radiation field alignment check, unit A failed to satisfy the national regulations. Concerning the timer reproducibility, 64% of the units failed to meet the criteria. All of the devices passed the rest of the checks satisfactorily. Conclusion: This study uncovered that most of the radiology rooms in Yazd province are in an adequate situation based on the QC tests; however, more than half of the units do not satisfy the timer reproducibility criteria. Hence, more supervision needs to be directed at these systems by qualified radiation safety officers who are responsible for the protection of the population against ionization radiation.


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