scholarly journals Variability in Effective Radiating Area at 1 MHz Affects Ultrasound Treatment Intensity

2008 ◽  
Vol 88 (1) ◽  
pp. 50-57 ◽  
Author(s):  
Stephen J Straub ◽  
Lennart D Johns ◽  
Samuel M Howard
Keyword(s):  
Large Deviations ◽  
Output Power ◽  
Measurement Techniques ◽  
Total Output ◽  
Treatment Intensity ◽  
Average Intensity ◽  
Spatial Average ◽  
Ultrasound Transducers ◽  
Total Output Power ◽  
Standardized Measurement

Background and Purpose Previous research has indicated that not all ultrasound transducers heat at equal rates; however, the cause of this disparity is unclear. Variability in spatial average intensity (SAI) has been implicated in this disparity at 3 MHz. This variability has not been explored at 1 MHz. Methods Sixty-six 5-cm2 ultrasound transducers were purchased from 6 different manufacturers. Transducers were calibrated and assessed for effective radiating area (ERA), total output power, and SAI using standardized measurement techniques. Results Total output power values fell within US Food and Drug Administration guidelines, but there were large variations in ERA. The resulting SAI values showed large deviations (−43% to +61%) from the digitally displayed value. Intra-manufacturer SAI values varied up to 53%. Discussion and Conclusion Spatial average intensity can vary largely from the values displayed on these ultrasound generators; in a calibrated cohort, this difference is primarily attributable to differences in measured ERA. Patterns of SAI variability within the manufacturer at 1 MHz do not follow previous reports of variability at 3 MHz.

scholarly journals Development of Cultured Muscles with Tendon Structures for Modular Bio-Actuators

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 379
Author(s):  
Takuto Nomura ◽  
Masaru Takeuchi ◽  
Eunhye Kim ◽  
Qiang Huang ◽  
Yasuhisa Hasegawa ◽  
...  
Keyword(s):  
Output Power ◽  
Chain Structure ◽  
Total Output ◽  
Total Output Power ◽  
Dc Voltage ◽  
Design Flexibility ◽  
Micro Robot ◽  
A Chain ◽  
Robot Body

In this article, we propose a new actuator named the modular bio-actuator (MBA). The MBA has two tendon structures made of polydimethylsiloxane (PDMS) at both ends of the bio-actuator. The MBA can be easily handled and fixed on an artificial micro-robot body to increase its design flexibility and output power. The tendon structures were connected to a bio-actuator in the form of a chain structure, and the connection between the tendon structures and the bio-actuator was maintained for more than three weeks. The contraction length of the MBA was linearly increased when the DC voltage applied to the MBA was increased. The MBA contracted over 200 µm when a DC voltage of 10 V and 1 Hz was applied to the bio-actuator. The output power of the MBA was measured using a PDMS cantilever, and the total output power of the MBA increased linearly when multiple MBAs were stacked on a PDMS cantilever. This study was aimed at improving the design flexibility and controllability of micro-robots and bionic systems.

Solar Concentration of 50,000 Achieved With Output Power Approaching 1 kW

1996 ◽  
Vol 118 (3) ◽  
pp. 141-145 ◽  
Author(s):  
D. Jenkins ◽  
R. Winston ◽  
J. Bliss ◽  
J. O’Gallagher ◽  
A. Lewandowski ◽  
...  
Keyword(s):  
Power Generation ◽  
Renewable Energy ◽  
Electric Power ◽  
Output Power ◽  
Total Output ◽  
National Renewable Energy Laboratory ◽  
Total Output Power ◽  
Electric Power Generation ◽  
New Device ◽  
The Future

We have achieved a 50,000 ± 3,000 times concentration of sunlight using a unique dielectric nonimaging concentrator in an experiment performed at the National Renewable Energy Laboratory. The scale of the experiment is several times larger than that of previous experiments. Total output power approaching 1 kW passes through a 4.6 mm diameter aperture. An extractor tip is added to the concentrator profile which allows measurement of flux levels using an air calorimeter. This new device has the potential to allow the use of dielectric concentrators at larger scale for thermal electric power generation. We report on the implications of this experiment for the future use of dielectric concentrators.

scholarly journals TUNABLE ULTRA-LONG RANDOM DISTRIBUTED FEEDBACK FIBER LASER

2016 ◽  
Vol 78 (3) ◽  
Author(s):  
Nadiah H. Z. Abidin ◽  
M. H. Abu Bakar ◽  
N. Tamchek ◽  
M. A. Mahdi
Keyword(s):  
Fiber Laser ◽  
Output Power ◽  
Rayleigh Scattering ◽  
Stimulated Raman Scattering ◽  
Single Mode ◽  
Gain Medium ◽  
Distributed Feedback ◽  
Total Output ◽  
Total Output Power ◽  
Symmetrical Configuration

A 72 km open-ended symmetrical tunable random distributed feedback fiber laser (RDB-FL) with different pumping schemes is presented in this study. The random distributed feedback was contributed by Rayleigh scattering in the single-mode fiber while distributed gain was provided by the effect of stimulated Raman scattering. The pumping schemes tested with the configuration was outward and inward pumping, where these would be backward and forward pumping in a non-symmetrical configuration of a fiber laser, respectively. The tuning range was also varied in conjunction with the different pumping schemes to determine the optimum performance. Random lasing in the RDB-FL was achieved by utilizing multiple scattering in the disordered gain medium to achieve resonance. With pump power limited to 1.5 W, the best threshold was measured as low as 1.4 W while the highest total output power was at 8 mW. In outward pumping configuration, the wavelengths that are within the maximum Raman gain (1555-1565 nm) show the best peak powers and total output power with a narrow linewidth, as low as 0.25 nm.

Impact of Generator Rating Increase, Ambient Pressure and Coolant Composition and Temperature on Power Generator Heat Exchangers

2010 ◽  
Author(s):  
Luis P. Zea
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Output Power ◽  
Heat Exchangers ◽  
Ambient Pressure ◽  
Operating Conditions ◽  
Total Output ◽  
Inlet Temperature ◽  
Total Output Power ◽  
Transfer Rates

Heat exchangers’ operating requirements vary depending on several parameters such as plant location, coolant input conditions and generator total output power. Some of these parameters play a more important role than others and understanding these roles is key to designing heat exchangers that will better suit their operating conditions. This paper analytically examines the implications that varying four parameters have on a heat exchanger with a fixed geometry and heat transfer area. Ambient pressure decrease translates into changes on the thermodynamic conditions of the gas flow. Coolant composition variances (from condensate to increased glycol percentages) also play an important role on the exchanger’s heat transfer rates, the higher the glycol percentage the lower the heat transfer rate. In the same manner, the coolant inlet temperature will partly determine heat transfer rates. Lastly, a generator total output power increase will yield higher heat losses on several points of the generator and thus, a higher heat load for the heat exchanger. The graphs and data hereby presented should be of assistance to those designing new coolers as well as those operating current ones.

The Power of Wind Turbine Generators Prediction Model Based on Time Series

2013 ◽  
Vol 860-863 ◽  
pp. 394-397
Author(s):  
Guan Jia Huang ◽  
Shao Mei Fang ◽  
Si Tu Qiaojun
Keyword(s):  
Wind Turbine ◽  
Output Power ◽  
Arima Model ◽  
Garch Model ◽  
Total Output ◽  
Total Output Power ◽  
Short Term ◽  
Turbine Generators ◽  
Wind Turbine Generators ◽  
Short Term Prediction

Author constructed ARIMA model and GARCH model to predict the output power of the 4 wind turbine generators (A, B, C, D) and the total output power of the 4 and 58 wind turbine generators. Whats more, by comparing the results of two methods, it shows that the result of GARCH model is more accurate than ARIMA model in short-term prediction.

scholarly journals Characterization of the acoustic output of therapeutic ultrasound equipment

1992 ◽  
Vol 48 (1) ◽  
pp. 4-8
Author(s):  
M. G. Van der Merwe ◽  
N. Bhagwandin ◽  
J. E. Van der Spuy ◽  
P. E. Le Roux
Keyword(s):  
Total Power ◽  
Ultrasound Therapy ◽  
Average Intensity ◽  
Spatial Average ◽  
Pressure Balance ◽  
Know How ◽  
Scanning Technique ◽  
Acoustic Output ◽  
Total Power Output

The safety and efficacy of ultrasound therapy may be compromised if the output from therapy transducers differs considerably from the indicated value. Although the total power output of a transducer can be easily measured using a pressure balance, it is also important to know how this energy is distributed through space. By using a hydrophone scanning technique, beam profiles of the energy distribution can be obtained. From the beam profiles various parameters such as the effective radiating area (ERA) and the beam non-uniformity ratio (BNR) can be determined. Since the spatial-average intensity selected for treatment is a ratio of the emitted ultrasound power and the effective radiating area, it is essential to be able to measure parameters like the effective radiating area. In this study ERA and BNR measurements for commercially available devices were performed with a hydrophone scanning technique.

Microscale electrostatic energy harvester using internal impacts

2012 ◽  
Vol 23 (13) ◽  
pp. 1409-1421 ◽  
Author(s):  
Cuong P Le ◽  
Einar Halvorsen ◽  
Oddvar Søråsen ◽  
Eric M Yeatman
Keyword(s):  
Energy Harvesting ◽  
Output Power ◽  
Inertial Mass ◽  
Electrostatic Energy ◽  
Mass Motion ◽  
Total Output ◽  
Additional Energy ◽  
Impact Device ◽  
Reference Device ◽  
The Impact

This article presents a new concept for electrostatic energy harvesting devices that increase output power under displacement limited inertial mass motion at sufficiently large acceleration amplitudes. The concept is illustrated by two demonstrated electrostatic energy harvesting prototypes in the same die dimension: a reference device with end-stops and an impact device with movable end-stops functioning as slave transducers. Both devices are analyzed and characterized in small and large excitation regimes. We found that significant additional energy from the internal impact force can be harvested by the slave transducer. The impact device gives much higher, up to a factor of 3.7, total output power than the reference device at the same high-acceleration amplitude. The bandwidth of the response to frequency sweeps is beneficially enlarged by up to a factor of 20 by the nonlinear mechanisms of the impact device.

A Two-Temperature, Gas-Particle Suspension in MHD Power Generation

1974 ◽  
Vol 96 (3) ◽  
pp. 267-273 ◽  
Author(s):  
D. J. Helfritch ◽  
W. A. Gustafson
Keyword(s):  
Output Power ◽  
Particle Temperature ◽  
Thermionic Emission ◽  
Total Output ◽  
Particle Suspension ◽  
Gas Temperature ◽  
Mhd Generator ◽  
Electrical Conductivities ◽  
Large Particles ◽  
Two Temperature

A feasibility study has been made of the use of a two-temperature, gas-particle suspension as the conducting medium in MHD generators. Large gas-particle temperature differences following nozzle expansions have been calculated, and the power generated by the use of these suspensions in MHD generator ducts has been investigated. Although relatively low gas temperatures have been considered, high electrical conductivities can be achieved by means of thermionic emission of electrons from high temperature particles. It is shown that total output power increases as gas temperature is decreased by means of continued nozzle expansion. Output power is also increased through the use of relatively large particles.

scholarly journals An Experimental and Comparative Performance Evaluation of a Hybrid Photovoltaic-Thermoelectric System

2021 ◽  
Vol 9 ◽  
Author(s):  
Muhammad Ahsan Iqbal Khan ◽  
Muhammad Irfan Khan ◽  
Ali Hussain Kazim ◽  
Aqsa Shabir ◽  
Fahid Riaz ◽  
...  
Keyword(s):  
Output Power ◽  
Conversion Efficiency ◽  
Hybrid System ◽  
Large Scale ◽  
Total Output ◽  
Photovoltaic Module ◽  
Rear Side ◽  
Pv System ◽  
Thermoelectric Modules ◽  
Pv Module

The majority of incident solar irradiance causes thermalization in photovoltaic (PV) cells, attenuating their efficiency. In order to use solar energy on a large scale and reduce carbon emissions, their efficiency must be enhanced. Effective thermal management can be utilized to generate additional electrical power while simultaneously improving photovoltaic efficiency. In this work, an experimental model of a hybrid photovoltaic-thermoelectric generation (PV-TEG) system is developed. Ten bismuth telluride-based thermoelectric modules are attached to the rear side of a 10 W polycrystalline silicon-based photovoltaic module in order to recover and transform waste thermal energy to usable electrical energy, ultimately cooling the PV cells. The experiment was then carried out for 10 days in Lahore, Pakistan, on both a simple PV module and a hybrid PV-TEG system. The findings revealed that a hybrid system has boosted PV module output power and conversion efficiency. The operating temperature of the PV module in the hybrid system is reduced by 5.5%, from 55°C to 52°C. Due to a drop in temperature and the addition of some recovered energy by thermoelectric modules, the total output power and conversion efficiency of the system increased. The hybrid system’s cumulative output power increased by 19% from 8.78 to 10.84 W, compared to the simple PV system. Also, the efficiency of the hybrid PV-TEG system increased from 11.6 to 14%, which is an increase of 17% overall. The results of this research could provide consideration for designing commercial hybrid PV-TEG systems.

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