Tribological contact stability of hard and soft cleaning projectiles

2014 ◽  
Vol 92 (8) ◽  
pp. 1353-1359 ◽  
Author(s):  
M. Reza Malayeri ◽  
Mohammad R. Jalalirad
2013 ◽  
Vol 133 (6) ◽  
pp. 229-236
Author(s):  
Yasushi Tomizawa ◽  
Yongfang Li ◽  
Akihiro Koga ◽  
Hiroshi Toshiyoshi ◽  
Yasuhisa Ando ◽  
...  

Micromachines ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 216
Author(s):  
Yongwei Li ◽  
Ting Liang ◽  
Cheng Lei ◽  
Qiang Li ◽  
Zhiqiang Li ◽  
...  

In this study, a preparation method for the high-temperature pressure sensor based on the piezoresistive effect of p-type SiC is presented. The varistor with a positive trapezoidal shape was designed and etched innovatively to improve the contact stability between the metal and SiC varistor. Additionally, the excellent ohmic contact was formed by annealing at 950 °C between Ni/Al/Ni/Au and p-type SiC with a doping concentration of 1018cm−3. The aging sensor was tested for varistors in the air of 25 °C–600 °C. The resistance value of the varistors initially decreased and then increased with the increase of temperature and reached the minimum at ~450 °C. It could be calculated that the varistors at ~100 °C exhibited the maximum temperature coefficient of resistance (TCR) of ~−0.35%/°C. The above results indicated that the sensor had a stable electrical connection in the air environment of ≤600 °C. Finally, the encapsulated sensor was subjected to pressure/depressure tests at room temperature. The test results revealed that the sensor output sensitivity was approximately 1.09 mV/V/bar, which is better than other SiC pressure sensors. This study has a great significance for the test of mechanical parameters under the extreme environment of 600 °C.


2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Ran Hao ◽  
E. Erdem Tuna ◽  
M. Cenk Çavuşoğlu

Abstract Contact force quality is one of the most critical factors for safe and effective lesion formation during catheter based atrial fibrillation ablation procedures. In this paper, the contact stability and contact safety of a novel magnetic resonance imaging (MRI)-actuated robotic cardiac ablation catheter subject to surface motion disturbances are studied. First, a quasi-static contact force optimization algorithm, which calculates the actuation needed to achieve a desired contact force at an instantaneous tissue surface configuration is introduced. This algorithm is then generalized using a least-squares formulation to optimize the contact stability and safety over a prediction horizon for a given estimated heart motion trajectory. Four contact force control schemes are proposed based on these algorithms. The first proposed force control scheme employs instantaneous heart position feedback. The second control scheme applies a constant actuation level using a quasi-periodic heart motion prediction. The third and the last contact force control schemes employ a generalized adaptive filter-based heart motion prediction, where the former uses the predicted instantaneous position feedback, and the latter is a receding horizon controller. The performance of the proposed control schemes is compared and evaluated in a simulation environment.


2002 ◽  
Vol 28 (2) ◽  
pp. 126-128
Author(s):  
N. R. Gall’ ◽  
E. V. Rut’kov ◽  
A. Ya. Tontegode

Author(s):  
Yesenia Gómez Taborda ◽  
Maryory Gómez Botero ◽  
Juan Guillermo Castaño-González ◽  
Angela Bermúdez-Castañeda

During their service life, modular interfaces experience tribological, and corrosion phenomena that lead to deterioration, which in turn can cause a revision procedure to remove the failed prosthesis. To achieve a clearer understanding of the surface performance of those biomedical alloys and the role of the surface properties in the mechanical and chemical performance, samples were taken from retrieval implants made of Ti6Al4V and Co28Cr6Mo alloys. Polarization resistance and pin-on-disk tests were performed on these samples. Physical properties such as contact angle, roughness, microhardness, and Young’s modulus were determined. A correlation between surface energy and evolution of the tribological contact was observed for both biomedical alloys. In tribocorrosion tests, titanium particles seem to remain in the surface, unlike what is observed in CoCr alloys. These metallic or oxidized particles could cause necrosis or adverse tissue reactions.


2018 ◽  
Vol 215 (23) ◽  
pp. 1800491 ◽  
Author(s):  
Sven Englund ◽  
Sigbjørn Grini ◽  
Olivier Donzel-Gargand ◽  
Valentina Paneta ◽  
Volodymyr Kosyak ◽  
...  

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