scholarly journals Radio Frequency MRI coils and safety: how infrared thermography can support quality assurance

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Barbara Testagrossa ◽  
Elisa Ruello ◽  
Sergio Gurgone ◽  
Lucia Denaro ◽  
Carlo Sansotta ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Temperature Variation ◽  
Temperature Increase ◽  
Medical Physics ◽  
Operating Conditions ◽  
Thermal Camera ◽  
Simple Method ◽  
Magnetic Imaging ◽  
Mri Scans ◽  
Mri Coils

Abstract Background The safety controls in Resonance Magnetic Imaging (MRI) diagnostic site are numerous and complex. Some of these are contained in international directives and regularly conducted by medical physics expert after acceptance tests, consisting of a series of checks, measurements, evaluations called quality controls (QCs) and made to guarantee the image quality of the equipment. In this context, ensuring that the coils are in proper operating conditions is important to prevent and reduce errors in use and to preserve patient safety. Results A study by thermography was conducted to evaluate temperature changes of MRI coils during Quality Control (QC), in order to prevent any problems for the patient due to Radio Frequency waves. This experiment involves use of a thermal camera to detect temperature variations during MRI scans using head and body coils of two different tomography 1.5 T and 3.0 T static magnetic field. Thermal camera was positioned inside the MRI room to acquire images every 15 s for all the scansions duration. The observations have shown a temperature increase only for body coil of 1.5 MRI tomography, whereas no significative temperature variation has occurred for the other coils under observation. This temperature increase was later related to a fault of such coil. Conclusions The authors believe this simple method useful as first approach, during routinely QCs, to verify coils functioning and so to avoid patient hazards and are preparing a methodological study about functioning of the coils with respect to their temperature variation.

Design Point for Predicting Year-Round Performance of Solar Parabolic Trough Concentrator Systems

2013 ◽  
Author(s):  
Men Wirz ◽  
Matthew Roesle ◽  
Aldo Steinfeld
Keyword(s):  
Operating Conditions ◽  
Transfer Model ◽  
Parabolic Trough ◽  
Specific System ◽  
Simple Method ◽  
Operating Condition ◽  
Average Efficiency ◽  
Design Point ◽  
Yearly Average ◽  
Solar Field

Thermal efficiencies of the solar field of two different parabolic trough concentrator (PTC) systems are evaluated for a variety of operating conditions and geographical locations, using a detailed 3D heat transfer model. Results calculated at specific design points are compared to yearly average efficiencies determined using measured direct normal solar irradiance (DNI) data as well as an empirical correlation for DNI. It is shown that the most common choices of operating conditions at which solar field performance is evaluated, such as the equinox or the summer solstice, are inadequate for predicting the yearly average efficiency of the solar field. For a specific system and location, the different design point efficiencies vary significantly and differ by as much as 11.5% from the actual yearly average values. An alternative simple method is presented of determining a representative operating condition for solar fields through weighted averages of the incident solar radiation. For all tested PTC systems and locations, the efficiency of the solar field at the representative operating condition lies within 0.3% of the yearly average efficiency. Thus, with this procedure, it is possible to accurately predict year-round performance of PTC systems using a single design point, while saving computational effort. The importance of the design point is illustrated by an optimization study of the absorber tube diameter, where different choices of operating conditions result in different predicted optimum absorber diameters.

Gas Cooling and Humidification: Design of Packed Towers from Small-Scale Tests

1950 ◽  
Vol 163 (1) ◽  
pp. 41-53 ◽  
Author(s):  
W. F. Carey ◽  
G. J. Williamson
Keyword(s):  
Operating Conditions ◽  
Total Heat ◽  
Small Scale ◽  
Water Cooling ◽  
Packed Tower ◽  
Simple Method ◽  
Worked Example ◽  
Gas Cooling ◽  
Heat Method ◽  
Working Out

On plants in which gases are processed, the gases are often brought into direct contact with water—usually in packed towers. The purpose may be to cool a hot gas, to increase the humidity of a gas, or, in the well-known special case of water-cooling towers, to cool water by contact with atmospheric air. These processes involve simultaneous transfers of sensible heat and water vapour, and existing methods of analysis are complex and laborious, except for the cooling of water, for which Merkel's total-heat method has long been available. Merkel's approximate solution offers the engineer a simple method of working out, for any operating conditions, the amount of heat transferred and the “driving force” available for transferring it. The present paper generalizes the total-heat method and, with a permissible sacrifice in accuracy, preserves the essential simplicity of the water-cooling treatment for gas-cooling and humidification processes. To complete the design of a packed tower, a knowledge is required of the characteristics of the packing. Information obtained in small towers is given for a number of packings, and a worked example shows how to apply the method of treatment, and the packing data presented, to the design of a large plant tower.

Ion Kinetic Energy Determinations in Radio-Frequency Glow Discharge Mass Spectrometry

1995 ◽  
Vol 49 (7) ◽  
pp. 917-926 ◽  
Author(s):  
Paula R. Cable ◽  
R. Kenneth Marcus
Keyword(s):  
Kinetic Energy ◽  
Glow Discharge ◽  
Radio Frequency ◽  
Source Region ◽  
Potential Method ◽  
Operating Conditions ◽  
Atmospheric Plasma ◽  
Radio Frequency Glow Discharge ◽  
Ion Trajectory ◽  
Ion Kinetic Energy

Radio-frequency glow discharge (rf-GD) sources produce an abundance of both atoms and ions. For the mass spectrometric application of the glow discharge technique, knowledge of the ion kinetic energies is required to optimize extraction and focusing of ions from the source region into the analyzer. This paper details kinetic energies experimentally determined with the use of the “retarding potential” method. For this study, the analyzer quadrupole of a double-quadrupole mass spectrometer was positively biased to act as a repeller. Ion kinetic energies (IKEs) determined for a variety of discharge and analyzer operating conditions ranged from 12.5 eV to 25.0 eV for 63Cu+. Kinetic energy measurements were confirmed from ion trajectory simulations and follow closely the experimental values for identical analyzer conditions and initial IKEs. Results of this study indicate that the conditions under which ions are formed (plasma conditions) affect IKEs and energy spreads to a greater extent than analyzer parameter variations. Different from atmospheric plasma sources, IKEs for rf-GD species do not vary as a function of ion mass/identity. Evidence is also given in support of a slight mass biasing owing to the transmission properties of double-quadrupole analyzers. The findings detailed herein demonstrate the effects of rf modulation on both ion kinetic energy values and distributions.

scholarly journals Automatic and Online Detection of Rotor Fault State

2018 ◽  
Vol 7 (1) ◽  
pp. 43 ◽  
Author(s):  
Ali Ouanas ◽  
Ammar Medoued ◽  
Salim Haddad ◽  
Mourad Mordjaoui ◽  
D. Sayad
Keyword(s):  
Induction Motor ◽  
Dimensional Space ◽  
Operating Conditions ◽  
Online Detection ◽  
K Nearest Neighbor ◽  
Simple Method ◽  
Important Place ◽  
Motor Test ◽  
Wide Range ◽  
Fault State

In this work, we propose a new and simple method to insure an online and automatic detection of faults that affect induction motor rotors. Induction motors now occupy an important place in the industrial environment and cover an extremely wide range of applications. They require a system installation that monitors the motor state to suit the operating conditions for a given application. The proposed method is based on the consideration of the spectrum of the single-phase stator current envelope as input of the detection algorithm. The characteristics related to the broken bar fault in the frequency domain extracted from the Hilbert Transform is used to estimate the fault severity for different load levels through classification tools. The frequency analysis of the envelope gives the frequency component and the associated amplitude which define the existence of the fault. The clustering of the indicator is chosen in a two-dimensional space by the fuzzy c mean clustering to find the center of each class. The distance criterion, the K-Nearest Neighbor (KNN) algorithm and the neural networks are used to determine the fault type. This method is validated on a 5.5-kW induction motor test bench.Article History: Received July 16th 2017; Received: October 5th 2017; Accepted: Januari 6th 2018; Available onlineHow to Cite This Article: Ouanas, A., Medoued, A., Haddad, S., Mordjaoui, M., and Sayad, D. (2017) Automatic and online Detection of Rotor Fault State. International Journal of Renewable Energy Development, 7(1), 43-52.http://dx.doi.org/10.14710/ijred.7.1.43-52

scholarly journals Evaluation of active sludge and aquatic ferns usage for removal of zinc in a biological wastewater treatment system

2019 ◽  
pp. 39-44
Author(s):  
Amir Hajiali ◽  
Lacramioara Diana Robescu
Keyword(s):  
Ph Value ◽  
Reaction Times ◽  
Treatment Method ◽  
Operating Conditions ◽  
Industrial Scale ◽  
Reactor Performance ◽  
Solution Ph ◽  
Active Sludge ◽  
Simple Method ◽  
Aquatic Fern

In this research capability of biological treatment method via active sludge and aquatic fern evaluated in different operating conditions and they were optimized in order to remove Zn (II). A simple reactor performance for treatment of model and real wastewater on laboratory and semi-industrial scale was investigated. This refining process proceeded with special attention to the effect of solution pH-value, pollutant concentration, absorbent concentration and reaction time. The batch semi-industrial scale reactor represented over 90 % removal efficiency under pH-value of 6 and 5-5.5 for aquatic ferns and active sludge, respectively. Effective reaction times represented various durations for aquatic ferns and active sludge with respect of 120 minutes and 90 minutes. The two biological masses had the best performances with 6 g/l for aquatic ferns and 5 g/l for active sludge. In the presence of 5 ppm of Zn (II) as the objective heavy metal, both absorbents had over 93.2 % removal efficiencies. While obviously laboratory-scale attempts introduced higher acceptable reduction efficiencies via this economic applicable treatment method. Additionally, economic considerations clarified feasibility of this recommended simple method.

Design Procedure of Spring Washers for Flanged Joints

2015 ◽  
Author(s):  
Mahmoud Nagi Shatla
Keyword(s):  
Critical Temperature ◽  
Temperature Increase ◽  
Rapid Heating ◽  
Design Procedure ◽  
Operating Conditions ◽  
The Other ◽  
Rapid Cooling ◽  
Systematic Procedure ◽  
Mode Of Failure ◽  
Rapid Temperature

Flanged joints may experience leaks due to rapid increases or decreases in process temperatures. The mode of failure of a flanged joint during a rapid temperature increase is usually manifested in the form of gasket crushing or bolt rupture. On the other hand, the mode of failure of a flanged joint during a rapid cooling event occurs as bolt loosening causing the bolts to lose the necessary pretention required for joint tightness. In the present work, a systematic procedure has been proposed to design/select spring washers to prevent gasket leaks during thermal upsets of flanged joints. The procedure is based on the maximum allowable bolt load which is equal to the minimum of the load that will overstress the bolt, the load that will overstress the flange, or the load that will crush the gasket. The procedure considers the minimum allowable bolt load which is equal to the maximum of the required bolt load for operating conditions and required bolt load for gasket seating conditions. Moreover, the proposed procedure considers the design for rapid heating or rapid cooling events of flanged joints. The proposed procedure is based on the load-deflection characteristics of spring washer assemblies (series, parallel and series-parallel arrangements). The procedure has been applied successfully to design spring washer assemblies for flanged joints that suffer critical temperature excursions.

Thermal Ratcheting of a Beam Element Having an Idealized Bauschinger Effect

1976 ◽  
Vol 98 (3) ◽  
pp. 264-271 ◽  
Author(s):  
T. M. Mulcahy
Keyword(s):  
Strain Hardening ◽  
Temperature Variation ◽  
Bauschinger Effect ◽  
Rectangular Cross Section ◽  
Beam Element ◽  
Operating Conditions ◽  
Hardening Material ◽  
Linear Temperature ◽  
Thermal Ratcheting ◽  
Breeder Reactors

Thermal ratcheting has been analytically investigated for a beam element subjected to a linear temperature variation across its solid rectangular cross section. A linear strain-hardening material response exhibiting an idealized Bauschinger effect was assumed. Formulas are given for the associated strain accumulation which are valid over a large range of strain hardening, temperature variation, temperature cycles, and axial load. Specific results are tabulated for the materials and operating conditions typically associated with liquid metal breeder reactors.

A numerical postprocessing procedure for analyzing radio frequency MRI coils

2011 ◽  
Vol 38A (4) ◽  
pp. 133-147 ◽  
Author(s):  
Rostislav A. Lemdiasov ◽  
Aghogho A. Obi ◽  
Reinhold Ludwig
Keyword(s):  
Radio Frequency ◽  
Mri Coils
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