Average power output and the power law: identifying trends in the behavior of fluidic harvesters in grid turbulence

2019 ◽  
Author(s):  
Kevin Ferko ◽  
Nick Chiappazzi ◽  
Jiawei Gong ◽  
Amir H. Danesh-Yazdi
Keyword(s):  
Power Law ◽  
Power Output ◽  
Average Power ◽  
Grid Turbulence ◽  
Average Power Output

Stochastic Dynamics of a Piezoelectric Energy Harvester Subjected to Lévy Flight Excitations

2017 ◽  
Author(s):  
Subramanian Ramakrishnan ◽  
Collin Lambrecht ◽  
Connor Edlund
Keyword(s):  
Power Output ◽  
Stochastic Dynamics ◽  
Duffing Oscillator ◽  
Average Power ◽  
Coupled System ◽  
Random Excitation ◽  
Small Scale ◽  
Vibration Energy Harvesting ◽  
Piezoelectric Energy ◽  
Average Power Output

Vibration energy harvesting seeks to exploit the energy of ambient random vibration for power generation, particularly in small scale devices. Piezoelectric transduction is often used as a conversion mechanism in harvesting and the random excitation is typically modeled as a Brownian stochastic process. However, non-Brownian excitations are of potential interest, particularly in the nonequilibrium regime of harvester dynamics. In this work, we investigate the averaged power output of a generic piezoelectric harvester driven by Brownian as well as (non-Brownian) Lévy stable excitations both in the linear and the Duffing regimes. First, a coupled system of stochastic differential equations that model the electromechanical system are presented. Numerical simulation results (based on the Euler-Maruyama scheme) that show the average power output from the system under Brownian and Lévy excitations are presented for the cases where the mechanical degree of freedom behaves as a linear as well as a Duffing oscillator. The results demonstrate that Lévy excitations result in higher expectation values of harvested power. In particular, increasing the noise intensity leads to significant increase in power output in the Levy case when compared with Brownian excitations.

Theoretical Performance Analysis of Solar Chimney Power Plant for Kota Region of Rajasthan, India

2015 ◽  
Vol 787 ◽  
pp. 157-161 ◽  
Author(s):  
Zainab Akhtar ◽  
K.V.S. Rao
Keyword(s):  
Power Plant ◽  
Solar Radiation ◽  
Power Output ◽  
Average Power ◽  
Energy Generation ◽  
Solar Chimney ◽  
Minute Interval ◽  
Average Power Output ◽  
Solar Chimney Power Plant ◽  
Theoretical Performance

A solar chimney power plant (SCPP) sometimes also called 'solar updraft tower' is a part of the solar thermal group of indirect solar conversion technologies, utilizing a combination of solar air collector and central updraft tube or chimney to generate a solar induced convective flow which drives pressure staged turbines to generate electricity. In this paper the performance of a solar chimney power plant (SCPP) is evaluated if established in the Kota region of Rajasthan in India. Kota has high intensity of solar radiation with more than 270 sunny days in a year. To investigate the theoretical performance evaluation of the solar chimney power plant in Kota region, total energy generation and average power output for every ten minute interval has been calculated on the basis of solar radiation and temperature data provided by Centre for wind energy Technology (C-WET) available for the period from June 2011-May 2012 for every ten minute interval. Subsequently day wise and month wise calculations have been performed for energy generation and power output for the year June 2011 - May 2012. Further, annual average power output of SCPP is calculated at Kota for different sets of dimensions of SCPP and assuming different values of collector efficiency. Power produced at the plant established in Kota region is compared with power output estimated by J. Schlaich by their experience gained from prototype of SCPP in Manzanares, Spain. Land area required for solar chimney power plant if installed in Kota region of Rajasthan India is calculated for 200 MW capacity plant.

Mood and Cycling Performance in Response to Three Weeks of High-Intensity, Short-Duration Overtraining, and a Two-Week Taper

1999 ◽  
Vol 13 (4) ◽  
pp. 444-457 ◽  
Author(s):  
Bonnie G. Berger ◽  
Robert W. Motl ◽  
Brian D. Butki ◽  
David T. Martin ◽  
John G. Wilkinson ◽  
...  
Keyword(s):  
Short Duration ◽  
Power Output ◽  
High Intensity ◽  
Average Power ◽  
Interval Training ◽  
The United States ◽  
Cycling Performance ◽  
Mood Disturbance ◽  
Average Power Output ◽  
And Performance

This study examined changes in mood and performance in response to high-intensity, short-duration overtraining and a subsequent taper. Pursuit cyclists (N = 8) at the United States Olympic Training Center completed the POMS and simulated 4-km pursuit performance tests throughout a six-week period. The six-week period included a baseline week, three weeks of overtraining that consisted primarily of high-intensity interval training, and a two-week taper. Total Mood Disturbance (TMD) scores displayed a quadratic polynomial effect across the three weeks of overtraining (p < .01), with the highest TMD scores occurring in the second week. Average TMD scores were lower during the taper than at baseline (p < .02) and lower at taper than overtraining (p < .0005). Cycling performance (pursuit time and average power output) improved during the three weeks of overtraining; additional improvements were observed during the taper. There were no significant correlations between TMD and performance. However, pursuit time, average power output, and mood disturbance scores were at optimal levels throughout the taper period. These findings suggest that high-intensity, short-duration overtraining may not result in an overtraining syndrome in 4-km pursuit cyclists.

The Effect of Superoxygenated Water on Blood Gases, Lactate, and Aerobic Cycling Performance

2007 ◽  
Vol 2 (4) ◽  
pp. 377-385 ◽  
Author(s):  
Lars R. McNaughton ◽  
Steve Kenney ◽  
Jason Siegler ◽  
Adrian W. Midgley ◽  
Ric J. Lovell ◽  
...  
Keyword(s):  
Exercise Test ◽  
Power Output ◽  
Average Power ◽  
Rest Period ◽  
Cycling Performance ◽  
Exercise Tests ◽  
Double Blind ◽  
Maximal Power Output ◽  
Physiological Variables ◽  
Average Power Output

Context:Recently, superoxygenated-water beverages have emerged as a new purported ergogenic substance.Purpose:This study aimed to determine the effects of superoxygenated water on submaximal endurance performance.Methods:Eleven active male subjects, VO2max 52.6 ± 4.8 mL · kg−1 · min−1, height 180.0 ± 2.0 cm, weight 76.0 ± 7.0 kg, age 24 ± 1.0 y (mean ± SD), completed a 45-min cycle-ergometry exercise test at 70% of their previously predicted maximal power output with a 10-min rest period, followed by a 15-min time trial (TT). Thirty minutes before the exercise test subjects consumed 15 mL of either superoxygenated water (E) or placebo (P; water mixed with low-chlorine solution). Subjects then completed the test again a week later for the other condition (double-blind, randomized). The physiological variables measured during exercise were VO2, VCO2, respiratory-exchange ratio (RER), VE, PO2, PCO2, blood lactate (bLa–), and heart rate (HR). Mean distance covered and the average power output for the 15-min TT were also measured as performance indicators.Results:There were no significant differences in VO2, VCO2, RER, VE, bLa−, PO2, and HR (P > .05) during the exercise tests. Neither were there any significant improvements in the total distance covered (P 9.01 ± 0.74 km vs E 8.96 ± 0.68 km, P > .05) or the average power output (P 186.7 ± 35.8 W vs E 179.0 ± 25.9 W, P > .05) during the 15-min TT.Conclusion:Based on these results the authors conclude that consuming 15 mL of superoxygenated water does not enhance submaximal or maximal TT cycling performance.

Carbohydrate-Electrolyte Feedings and 1h Time Trial Cycling Performance

2004 ◽  
Vol 14 (5) ◽  
pp. 541-549 ◽  
Author(s):  
Ben Desbrow ◽  
Sally Anderson ◽  
Jennifer Barrett ◽  
Elissa Rao ◽  
Mark Hargreaves
Keyword(s):  
Power Output ◽  
High Intensity ◽  
Average Power ◽  
Time Trial ◽  
Cycling Performance ◽  
Dietary Regimen ◽  
Trained Subjects ◽  
Sports Drink ◽  
Average Power Output ◽  
Glucose Availability

The effects of a commercial sports drink on performance in high-intensity cycling was investigated. Nine well-trained subjects were asked to complete a set amount of work as fast as possible (time trial) following 24 h of dietary (subjects were provided with food, energy 57.4 ± 2.4 kcal/kg and carbohydrate 9.1 ± 0.4 g/kg) and exercise control. During exercise, subjects were provided with 14 mL/kg of either 6% carbohydrate-electrolyte (CHO-E) solution or carbohydrate-free placebo (P). Results showed that subjects’ performances did not greatly improve (time, 62:34 ± 6:44 min:sec (CHO-E) vs. 62:40 ± 5:35 min:sec (P); average power output, 283.0 ± 25.0 W (CHO-E) vs. 282.9 ± 29.3 W (P), P > 0.05) while consuming the sports drink. It was concluded that CHO-E consumption throughout a 1-h time trial, following a pre-exercise dietary regimen designed to optimize glucose availability, did not improve time or power output to a greater degree than P in well-trained cyclists.

The Isocapnic Buffering Phase and Mechanical Efficiency: Relationship to Cycle Time Trial Performance of Short and Long Duration

2005 ◽  
Vol 30 (1) ◽  
pp. 46-60 ◽  
Author(s):  
David J. Bentley ◽  
Veronica E. Vleck ◽  
Gregoire P. Millet
Keyword(s):  
Power Output ◽  
Average Power ◽  
Time Trial ◽  
Mechanical Efficiency ◽  
Incremental Test ◽  
Long Duration ◽  
Average Power Output ◽  
And Performance ◽  
The Relationship

The purpose of this study was to determine the relationship between the isocapnic buffer (βisocapnic) and hypocapnic hyperventilation (HHV) phases as well as performance in a short (20-min) and long (90-min) time trial (TT) in trained athletes. In addition, gross (GE, %) and delta (ΔE, %) efficiency were calculated and the relationship between these variables and the average power output (W) in each TT was determined. Thirteen male endurance athletes (Mean ± SD age 31 ± 6 yrs; body mass 75.6 ± 6.3 kg; height 185 ± 6 cm) completed a continuous incremental test to exhaustion for determination of the βisocapnic and HHV phases. A second submaximal test was used to determine GE and ΔE. The average power output (W) was measured in a 20-min and 90-min cycling TT. The βisocapnic phase (W) was significantly correlated to the average power output (W) in the 20-min TT (r = 0.58; p <  0.05), but not in the 90-min TT (r = 0.28). The HHV phase (W) was not significantly correlated to the average power output in the 20-min or 90-min TT. No significant correlation was found for GE or for ΔE and performance in the TT. The data from this study shows that βisocapnic together with HHV is not likely to be a useful indicator of cycle TT performance of 20- to 90-min duration. Furthermore, GE and ΔE determined from a submaximal incremental stepwise test are not related to cycling TT performance of different duration. Key words: incremental, correlation, metabolism, athletes, fatigue

Maximizing Average Power Output of an Airborne Wind Energy Generator Under Parametric Uncertainties

2015 ◽  
Author(s):  
Michelle A. Kehs ◽  
Chris Vermillion ◽  
Hosam K. Fathy
Keyword(s):  
Wind Speed ◽  
Wind Energy ◽  
Power Output ◽  
Average Power ◽  
Extremum Seeking ◽  
Energy Output ◽  
Wind Speeds ◽  
Average Power Output ◽  
The Difference ◽  
Optimal Average

This paper presents a controller for maximizing the time-averaged power output from an airborne wind energy generator in uncertain wind conditions. This system’s optimal energy output often involves flying in periodic figure-8 trajectories, but the precise optimal figure-8 shape is sensitive to environmental conditions, including wind speed. The literature presents controllers that are able to adapt to uncertainties, and this work expands on the current literature by using an extremum seeking based method. Extremum seeking is particularly well-suited for this application because of its well understood stability properties. In this work, extremum seeking is used to search through a family of optimal trajectories (computed offline) that correspond to discrete wind speeds. The controller is efficient in that it only searches for the optimum trajectory over the uncertain parameter (in this paper, wind speed). Results show that the controller converges to the optimal trajectory, provided it is initialized to a stable figure-8. The speed of convergence is dependent on the difference between the initial average power output and the optimal average power output.

Design and Analysis of a Rotor Blade Optimized for Extracting Energy From the Florida Current

2011 ◽  
Author(s):  
James H. VanZwieten ◽  
Carey M. Oster ◽  
Alana E. S. Duerr
Keyword(s):  
Power Output ◽  
Average Power ◽  
Energy Resource ◽  
Ocean Current ◽  
Florida Current ◽  
Current Profile ◽  
Shaft Power ◽  
Average Power Output ◽  
Bladed Rotor ◽  
Hydrodynamic Optimization

The Florida Current flowing past Southeast Florida represents an untapped renewable energy resource with a mean kinetic energy flux near its core of 2.32 kW/m2. The research presented in this paper details the hydrodynamic optimization of a three meter diameter, three-bladed rotor for an experimental research turbine. The proposed deployment site for this turbine is located 24 km off the coast of Southeast Florida in 300 m of water. At this location, thirteen months of continuous ocean current profile measurements have been collected. A genetic algorithm rotor optimization code was used to vary the geometry of the proposed rotor to maximize the average power output using the oceanographic measurements. The optimized rotor, operating in the observed flow field, is predicted to produce a mean shaft power of 7.153 kW when operating at 40 RPM. A sensitivity analysis shows that by increasing the RPM by 25% and 50%, the average power output can be increased by 3.56% and 4.99% respectively. Additionally, using a four-bladed rotor can increase the average power output by 4.22% when operating at 40 RPM.

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