Power Output Force Generation by a MEMS Phase Change Actuator

2011 ◽  
Vol 20 (6) ◽  
pp. 1287-1297 ◽  
Author(s):  
Leland W. Weiss ◽  
Cill D. Richards ◽  
Robert F. Richards
Keyword(s):  
Phase Change ◽  
Power Output ◽  
Force Generation ◽  
Output Force

Free radicals in hypoxic rat diaphragm contractility: no role for xanthine oxidase

2001 ◽  
Vol 281 (6) ◽  
pp. L1402-L1412 ◽  
Author(s):  
Leo M. A. Heunks ◽  
Herwin A. Machiels ◽  
Ronney de Abreu ◽  
Xiao Ping Zhu ◽  
Henricus F. M. van der Heijden ◽  
...  
Keyword(s):  
Free Radicals ◽  
Xanthine Oxidase ◽  
Power Output ◽  
Harmful Effect ◽  
Force Generation ◽  
Muscle Performance ◽  
Rat Diaphragm ◽  
Shortening Velocity ◽  
Contraction Pattern

Recent evidence indicates that hypoxia enhances the generation of oxidants. Little is known about the role of free radicals in contractility of the rat diaphragm during hypoxia. We hypothesized that antioxidants improve contractility of the hypoxic rat diaphragm and that xanthine oxidase (XO) is an important source of free radicals in the hypoxic diaphragm. The effects of N-acetylcysteine (NAC; 18 mM), Tiron (10 mM), and the XO inhibitor allopurinol (250 μM) were studied on isometric and isotonic force generation during hypoxia (Po 2 ∼7 kPa). NAC and Tiron decreased maximal force generation, slowed the shortening velocity, and decreased the power output. Fatigue rate was decreased in the presence of either NAC or Tiron. Allopurinol did not alter the contractility or fatigability of the diaphragm. During hyperoxia (Po 2 ∼85 kPa), neither NAC nor allopurinol affected the contractility or fatigability of the diaphragm. Thus free radicals play a significant role in diaphragm contractility during hypoxia. Whether antioxidants exert a beneficial or harmful effect on muscle performance depends on the contraction pattern of the muscle. Free radicals generated by XO do not play a role in diaphragm contractility during either hypoxia or hyperoxia.

Performance Improvement of Gas Turbine Power Plant by Intake Air Passive Cooling Using Phase Change Material Based Heat Exchanger

2017 ◽  
Author(s):  
Devendra Dandotiya ◽  
Nitin D. Banker
Keyword(s):  
Heat Exchanger ◽  
Ambient Temperature ◽  
Phase Change ◽  
Gas Turbine ◽  
Air Temperature ◽  
Power Output ◽  
Ambient Air ◽  
Passive Cooling ◽  
Air Intake ◽  
Change Material

The power output of a gas turbine plant decreases with the increase in ambient temperature. Moreover, the ambient temperature fluctuates about 15–20°C in a day. Hence, cooling of intake air makes a noticeable improvement to the gas turbine performance. In this regard, various active cooling techniques such as vapor compression refrigeration, vapor absorption refrigeration, vapor adsorption refrigeration and evaporative cooling are applied for the cooling of intake air. This paper presents a new passive cooling technique where the intake air temperature is reduced by incorporating phase change material (PCM) based heat exchanger parallel to conventional air intake line. During the daytime, the air is passed through the PCM which has melting temperature lower than the peak ambient temperature. This will reduce the ambient air temperature before taking to the compressor. Once the PCM melts completely, the required ambient air would be drawn from the ambient through conventional air intake arrangement. During the night, when there is lower ambient temperature, PCM converts from liquid to solid. The selected PCM has a melting temperature less than the peak ambient temperature and higher than the minimum ambient temperature. It is observed from the numerical modeling of the PCM that about four hours are required for the melting of PCM and within this time, the intake air can also be cooled by 5°C. The thermodynamic analysis of the results showed about 5.2% and 5.2% improvement in net power output and thermal efficiency, respectively for four hours at an ambient temperature of 45°C.

Effects of Phase Change Material on Solar Panel Power Output

2020 ◽  
Author(s):  
Alexander J. McConkey ◽  
Elliott Nguyen ◽  
Jake Perlman ◽  
Sydney Seto ◽  
Grant Setzler
Keyword(s):  
Phase Change ◽  
Phase Change Material ◽  
Power Output ◽  
Solar Panel ◽  
Change Material

Power Output and Technique of Wheelchair Athletes

1994 ◽  
Vol 11 (1) ◽  
pp. 71-85 ◽  
Author(s):  
Karin Roeleveld ◽  
Eric Lute ◽  
Dirkjan Veeger ◽  
Luc van der Woude ◽  
Tom Gwinn
Keyword(s):  
Power Output ◽  
Peak Exercise ◽  
Total Force ◽  
Propulsive Force ◽  
Mean Power ◽  
Wheelchair Athletes ◽  
Output Force ◽  
Braking Torque ◽  
The Right ◽  
Mean Power Output

To assess power output, force application, and kinematics of wheelchair propulsion in peak exercise, nine wheelchair athletes with medical lesion levels of T8 or lower performed a 30-s sprint test on a stationary wheelchair ergometer. Mean power output, calculated for the right wheel only, was 59.4 ± 8.5 W. The ratio between effective force and total propulsive force was 60 ± 6%. A negative torque around the hand and a not tangentially directed total force accounted for this low effectiveness. Since the subject group was highly trained, their technique was considered to be optimal for the given circumstances. Therefore, athletes who want to improve power output by increasing effectiveness should keep in mind the existence of a nontangential propulsive force and a braking torque applied by the hands onto the hand rim surface. It is likely that both aspects will be influenced by the geometry of the wheelchair, for example, hand rim dimension or seat position.

scholarly journals Muscle fatigue examined at different temperatures in experiments on intact mammalian (rat) muscle fibers

2009 ◽  
Vol 106 (2) ◽  
pp. 378-384 ◽  
Author(s):  
H. Roots ◽  
G. Ball ◽  
J. Talbot-Ponsonby ◽  
M. King ◽  
K. McBeath ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Power Output ◽  
Force Depression ◽  
Output Force ◽  
Different Temperatures ◽  
Force Velocity ◽  
C 30 ◽  
C 50 ◽  
Shortening Contractions

In experiments on small bundles of intact fibers from a rat fast muscle, in vitro, we examined the decline in force in repeated tetanic contractions; the aim was to characterize the effect of shortening and of temperature on the initial phase of muscle fatigue. Short tetanic contractions were elicited at a control repetition rate of 1/60 s, and fatigue was induced by raising the rate to 1/5 s for 2–3 min, both in isometric mode (no shortening) and in shortening mode, in which each tetanic contraction included a ramp shortening at a standard velocity. In experiments at 20°C ( n = 12), the force decline during a fatigue run was 25% in the isometric mode but was significantly higher (35%) in the shortening mode. In experiments at different temperatures (10–30°C, n = 11), the tetanic frequency and duration were adjusted as appropriate, and for shortening mode, the velocity was adjusted for maximum power output. In isometric mode, fatigue of force was significantly less at 30°C (∼20%) than at 10°C (∼30%); the power output (force × velocity) was >10× higher at 30°C than at 10°C, and power decline during a fatigue run was less at 30°C (∼20–30%) than at 10°C (∼50%). The finding that the extent of fatigue is increased with shortening contractions and is lower at higher temperatures is consistent with the view that force depression by inorganic phosphate, which accumulates within fibers during activity, may be a primary cause of initial muscle fatigue.

T03 Self-induced Oscillation of Water Column Caused by Phase Change II : Analysis of Properties and Method of Power Output

2005 ◽  
Vol 2005.9 (0) ◽  
pp. 51-52
Author(s):  
Takashi NAKAMURA ◽  
Kenta NAKADAI ◽  
Iwao YAMASHITA ◽  
Kazuhiro HAMAGUCHI
Keyword(s):  
Phase Change ◽  
Water Column ◽  
Power Output

Effect of stimulation frequency on force, net power output, and fatigue in mouse soleus muscle in vitro

2009 ◽  
Vol 87 (3) ◽  
pp. 203-210 ◽  
Author(s):  
George Vassilakos ◽  
Rob. S. James ◽  
Valerie M. Cox
Keyword(s):  
Electrical Stimulation ◽  
Fatigue Test ◽  
Soleus Muscle ◽  
Power Output ◽  
Fatigue Tests ◽  
Stimulation Frequency ◽  
Force Generation ◽  
Net Power Output ◽  
Work Loop

The effects of electrical stimulation frequency on force, work loop power output, and fatigue of mouse soleus muscle were investigated in vitro at 35 °C. Increasing stimulation frequency did not significantly affect maximal isometric tetanic stress (overall mean ± SD, 205 ± 16.6 kN·m–2 between 70 and 160 Hz) but did significantly increase the rate of force generation. The maximal net power output during work loops significantly increased with stimulation frequency: 18.2 ± 3.7, 22.5 ± 3.3, 26.8 ± 3.7, and 28.6 ± 3.4 W·kg–1 at 70, 100, 130, and 160 Hz, respectively. The stimulation frequency that was used affected the pattern of fatigue observed during work loop studies. At stimulation frequencies of 100 and 130 Hz, there were periods of mean net negative work during the fatigue tests due to a slowing of relaxation rate. In contrast, mean net work remained positive throughout the fatigue test when stimulation frequencies of 70 and 160 Hz were used. The highest cumulative work during the fatigue test was performed at 70 and 160 Hz, followed by 130 Hz, then 100 Hz. Therefore, stimulation frequency affects power output and the pattern of fatigue in mouse soleus muscle.

The effect of an aluminum heat-sink layer on the laser-induced amorphization of SiOx/TeGeSn/SiOx phase-change recording films

1989 ◽  
Vol 47 ◽  
pp. 574-575
Author(s):  
Matthew R. Libera ◽  
Martin Chen
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Heat Sink ◽  
Multilayer Film ◽  
Glassy Phase ◽  
Film Structure ◽  
Glass Forming ◽  
Active Storage ◽  
Dielectric Layers ◽  
Amorphous States

Phase-change erasable optical storage is based on the ability to switch a micron-sized region of a thin film between the crystalline and amorphous states using a diffraction-limited laser as a heat source. A bit of information can be represented as an amorphous spot on a crystalline background, and the two states can be optically identified by their different reflectivities. In a typical multilayer thin-film structure the active (storage) layer is sandwiched between one or more dielectric layers. The dielectric layers provide physical containment and act as a heat sink. A viable phase-change medium must be able to quench to the glassy phase after melting, and this requires proper tailoring of the thermal properties of the multilayer film. The present research studies one particular multilayer structure and shows the effect of an additional aluminum layer on the glass-forming ability.

Sign in / Sign up

Export Citation Format

Share Document