scholarly journals Electrical and Optical Impulse Response of High-Speed Micro-OLEDs Under UltraShort Pulse Excitation

2017 ◽  
Vol 64 (7) ◽  
pp. 2942-2948 ◽  
Author(s):  
Lei Zeng ◽  
Alex Chamberlain Chime ◽  
Mahmoud Chakaroun ◽  
Souheil Bensmida ◽  
Homere Nkwawo ◽  
...  
Author(s):  
Daejong Kim ◽  
Brian Nicholson ◽  
Lewis Rosado ◽  
Garry Givan

Foil bearings are one type of hydrodynamic air/gas bearings but with a compliant bearing surface supported by structural material that provides stiffness and damping to the bearing. The hybrid foil bearing (HFB) in this paper is a combination of a traditional hydrodynamic foil bearing with externally-pressurized air/gas supply system to enhance load capacity during the start and to improve thermal stability of the bearing. The HFB is more suitable for relatively large and heavy rotors where rotor weight is comparable to the load capacity of the bearing at full speed and extra air/gas supply system is not a major added cost. With 4,448N∼22,240N thrust class turbine aircraft engines in mind, the test rotor is supported by HFB in one end and duplex rolling element bearings in the other end. This paper presents experimental work on HFB with diameter of 102mm performed at the US Air force Research Laboratory. Experimental works include: measurement of impulse response of the bearing to the external load corresponding to rotor’s lateral acceleration of 5.55g, forced response to external subsynchronous excitation, and high speed imbalance response. A non-linear rotordynamic simulation model was also applied to predict the impulse response and forced subsynchronous response. The simulation results agree well with experimental results. Based on the experimental results and subsequent simulations, an improved HFB design is also suggested for higher impulse load capability up to 10g and rotordynamics stability up to 30,000rpm under subsynchronous excitation.


2012 ◽  
Vol 24 (12) ◽  
pp. 125104 ◽  
Author(s):  
Aniruddha Sinha ◽  
Hind Alkandry ◽  
Martin Kearney-Fischer ◽  
Mo Samimy ◽  
Tim Colonius

2018 ◽  
Vol 7 (2.7) ◽  
pp. 733
Author(s):  
C Priyanka ◽  
N Manoj Kumar ◽  
L Sai Priya ◽  
B Vaishnavi ◽  
M Rama Krishna

Convolution is having extensive area of application in Digital Signal Processing. Convolution supports to evaluate the output of a system with arbitrary input, with information of impulse response of the system.  Linear systems features are totally stated by the systems impulse response, as ruled by the mathematics of convolution. Primary necessity of any application to work fast is that rise in the speed of their basic building block. Multiplier, adder is said to be the important building blocks in the process of convolution. As these blocks consumes plentiful time to obtain the response of the system.  Several methods are designed to progress the speed of the Multiplier and adder, among all GDI (Gate Diffusion Input) is under emphasis because of faster working and low power consumption. In this paper GDI based convolution is implemented using Vedic multiplier and adder in T-SPICE Software which increases the speed and consumes less power compared to CMOS technology. 


Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4533
Author(s):  
Pavel Adamčík ◽  
Zuzana Murčinková

The impulse response of a rolling bearing and its principal component, the elasto-hydrodynamic lubrication film (EHDL), are analysed. When measuring the vibrations of bearings, we observed that the impulse response was mostly caused by defects (fatigue damage) on the raceways and/or rolling elements. However, this phenomenon can also occur in new defect-free roller bearings, where it is not commonly expected. This study presents an experiment that identifies the conditions of dynamic excitation for the impulse response of the EHDL, the source of which is not defects, but the EHDL itself. The EHDL responds in the form of impulses in case the velocity of its radial deformation is too fast. This is an unfavourable phenomenon that significantly shortens the service life of bearings. To analyse the dynamic excitation conditions, a testing bench at speeds up to 135,000 rpm with a flat belt drive was used. The testing bench enabled the formation of the so-called beat excitation from two harmonic excitation forces close in rotational frequency. The subject of this study is a defect-free high-speed double-row angular contact ball bearing used in the textile industry. We also present other physical conditions for the occurrence of undesired impulse responses that are caused by the EHDL.


1989 ◽  
Vol 28 (10) ◽  
Author(s):  
N. K. Sherman ◽  
F. Brunel ◽  
P. B. Corkum ◽  
F. A. Hegmann

2021 ◽  
pp. 108335
Author(s):  
H. Tang ◽  
P. Psota ◽  
J.J. Rosowski ◽  
C. Furlong ◽  
J.T. Cheng

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