scholarly journals Optimisation of a Heat Source for Infrared Thermography Measurements: Comparison to Mehler Engineering + Service-Heater

2020 ◽  
Vol 10 (4) ◽  
pp. 1285
Author(s):  
Simon Verspeek ◽  
Bart Ribbens ◽  
Xavier Maldague ◽  
Gunther Steenackers
Keyword(s):  
Heat Source ◽  
Narrow Band ◽  
Excitation Power ◽  
Heated Region ◽  
Heating Source ◽  
Active Thermography ◽  
Wide Range ◽  
Measurement Results ◽  
Processing Of Measurement Results ◽  
Line Scan Thermography

Using an optimised heating source in active thermography can facilitate the processing of measurement results. By designing a custom heat source for dynamic line scan thermography, we reduced the excitation power needed to heat the sample and decreased the unwanted side effects originating of a wide-range heating source. The design started from a regular halogen tube lamp and a reflector is composed to provide the desired heating power in a narrow band. The reflector shape is optimised using ray-tracing software to concentrate the electromagnetic radiation along with the heat in a slim line. A comparison between the optimised heat source and a commercially available line-heater is performed. The width of the heated region from the Mehler Engineering + Service-heater is larger than prescribed in the datasheet. The optimised line heater has several advantages over the comercially available heat source.

scholarly journals Expanded uncertainty evaluation taking into account the correlation between estimates of input quantities

2021 ◽  
pp. 4-8
Author(s):  
Igor Zakharov ◽  
Pavel Neyezhmakov ◽  
Olesia Botsiura
Keyword(s):  
Measurement Uncertainty ◽  
Correlation Coefficient ◽  
Degrees Of Freedom ◽  
Reduction Method ◽  
Standard Uncertainty ◽  
Effective Number ◽  
Expanded Uncertainty ◽  
Wide Range ◽  
Measurement Results ◽  
Processing Of Measurement Results

An expression for estimating the combined standard uncertainty taking into account the observed correlation between the estimates of the two input quantities is given. The Welch – Satterthwaite formula given in the GUM is analyzed. It is shown that the number of degrees of freedom calculated using this formula will vary over a wide range when the value of the correlation coefficient changes, and in some cases it may take an unacceptable zero value. An expression for calculating the combined standard uncertainty by the reduction method is given. It is shown that the number of degrees of freedom in this method does not depend on the value of the correlation coefficient. A formula for calculating the effective number of degrees of freedom taking into account the observed correlation is proposed. The existing expression for calculating the kurtosis of the measurand is analyzed and an expression is proposed for calculating the kurtosis of the measurand in the presence of a correlation between the input quantities. An example of estimation of expanded uncertainty when measuring the coefficient of a pressure transducer using a calibrator is considered. Estimates of the distribution of the measurand, obtained using Monte Carlo simulation, showed that they are closest to the estimates obtained by the kurtosis method. The considered example showed that taking into account the correlation in the processing of measurement results makes it possible to reduce the expanded measurement uncertainty of the converter coefficient by 1.22–1.27 times. Keywords: measurement uncertainty; correlation; effective number of degrees of freedom; method of kurtosis

DEVELOPMENT OF METHODS FOR ACQUIRING AND TRANSFERING MEASUREMENT DATA IN TESTING THE ELECTRIC LOCOMOTIVES

Transport ◽  
2012 ◽  
Vol 26 (4) ◽  
pp. 367-374
Author(s):  
Dragutin Kostić ◽  
Vujo Drndarević ◽  
Petar Marković ◽  
Nenad Jevtić
Keyword(s):  
Measurement Data ◽  
Longitudinal Force ◽  
Laboratory Model ◽  
Regulation System ◽  
Interface Circuits ◽  
Multichannel Measurement ◽  
Wide Range ◽  
Measurement Results ◽  
Processing Of Measurement Results

The paper describes procedures and methods upon which a system has been developed for testing the running behavior of new or reconstructed electric locomotives prior to release them into regular service. Special attention has been paid to precise measurement of traction currents and voltages, as well as non-electrical quantities, such as torque, longitudinal force exerted at the wheel rim, angular and linear velocity, which vary in a wide range. In addition to choosing appropriate sensors and measuring transducers, specific interface circuits were designed and manufactured, and a laboratory model for measuring electrical and non-electrical quantities of traction electric motors was developed and realised. Based on the experience and the results obtained from the laboratory model, a computerised data acquisition system for testing the electric locomotives in the field was designed from such a computerised systems as application program for simultaneous multichannel measurement of mechanical and electrical quantities, and for off-line processing of measurement results. The systems were tested during the operation on measurement and analysis of tractive capabilities, quality of anti slip regulation system, and energy consumption of a modernized locomotive.

scholarly journals RELaTED Project: New Developments on Ultra-Low Temperature District Heating Networks

Proceedings ◽  
2020 ◽  
Vol 65 (1) ◽  
pp. 25
Author(s):  
Antonio Garrido Marijuan ◽  
Roberto Garay ◽  
Mikel Lumbreras ◽  
Víctor Sánchez ◽  
Olga Macias ◽  
...  
Keyword(s):  
Low Temperature ◽  
High Performance ◽  
Waste Heat ◽  
District Heating ◽  
Hot Water ◽  
Thermal Systems ◽  
Heating Source ◽  
Wide Range ◽  
Thermal Sources ◽  
Heating Networks

District heating networks deliver around 13% of the heating energy in the EU, being considered as a key element of the progressive decarbonization of Europe. The H2020 REnewable Low TEmperature District project (RELaTED) seeks to contribute to the energy decarbonization of these infrastructures through the development and demonstration of the following concepts: reduction in network temperature down to 50 °C, integration of renewable energies and waste heat sources with a novel substation concept, and improvement on building-integrated solar thermal systems. The coupling of renewable thermal sources with ultra-low temperature district heating (DH) allows for a bidirectional energy flow, using the DH as both thermal storage in periods of production surplus and a back-up heating source during consumption peaks. The ultra-low temperature enables the integration of a wide range of energy sources such as waste heat from industry. Furthermore, RELaTED also develops concepts concerning district heating-connected reversible heat pump systems that allow to reach adequate thermal levels for domestic hot water as well as the use of the network for district cooling with high performance. These developments will be demonstrated in four locations: Estonia, Serbia, Denmark, and Spain.

A Transient Simulation of Heated Soil Vapor Extraction System

Volume 1 ◽  
2004 ◽  
Author(s):  
T. Roy ◽  
R. S. Amano ◽  
J. Jatkar
Keyword(s):  
Heat Source ◽  
Three Dimensional ◽  
Soil Vapor Extraction ◽  
Extraction System ◽  
Vapor Extraction ◽  
Predictive Tool ◽  
Heating Source ◽  
Time Required ◽  
Heated Soil ◽  
Remediation Process

Soil remediation process by heated soil vapor extraction system has drawn considerably attention for the last few years. The areas around chemical companies or waste disposal sites have been seriously contaminated from the chemicals and other polluting materials that are disposed off. Our present study is concentrated on modeling one transient Heated Soil Vapor Extraction System and predicting the time required for effective remediation. The process developed by Advanced Remedial Technology, consists of a heating source pipe and the extraction well embedded in the soil. The number of heat source pipes and the extraction wells depends on the type of soil, the type of pollutants, moisture content of the soil and the size of the area to be cleaned. The heat source heats the soil, which is transported in the interior part of the soil by means of conduction and convection. This heating of soil results in vaporization of the gases, which are then driven out of the soil by the extraction well. The extraction well consists of the blower which would suck the vaporized gases out of the system. A three-dimensional meshed geometry was developed using gambit. Different boundary conditions were used for heating and suction well and for other boundaries. Concentrations of different chemicals were collected from the actual site and this data was used as an initial condition. The analysis uses the species transport and discrete phase modeling to predict the time required to clean the soil under specific conditions. This analysis could be used for predicting the changes of chemical concentrations in the soil during the remediation process. This will give us more insight to the physical phenomena and serve as a numerical predictive tool for more efficient process.

Calculation of Nonlinear Systems Under Narrow Band Excitation Using Equivalent Linearization and Path Continuation

2021 ◽  
Author(s):  
Alwin Förster ◽  
Lars Panning-von Scheidt
Keyword(s):  
Nonlinear Systems ◽  
Narrow Band ◽  
Gaussian White Noise ◽  
Random Excitation ◽  
Mean Value ◽  
Equivalent Linearization ◽  
Efficient Procedure ◽  
Stochastic Excitations ◽  
Wide Range ◽  
The One

Abstract Turbomachines experience a wide range of different types of excitation during operation. On the structural mechanics side, periodic or even harmonic excitations are usually assumed. For this type of excitation there are a variety of methods, both for linear and nonlinear systems. Stochastic excitation, whether in the form of Gaussian white noise or narrow band excitation, is rarely considered. As in the deterministic case, the calculations of the vibrational behavior due to stochastic excitations are even more complicated by nonlinearities, which can either be unintentionally present in the system or can be used intentionally for vibration mitigation. Regardless the origin of the nonlinearity, there are some methods in the literature, which are suitable for the calculation of the vibration response of nonlinear systems under random excitation. In this paper, the method of equivalent linearization is used to determine a linear equivalent system, whose response can be calculated instead of the one of the nonlinear system. The method is applied to different multi-degree of freedom nonlinear systems that experience narrow band random excitation, including an academic turbine blade model. In order to identify multiple and possibly ambiguous solutions, an efficient procedure is shown to integrate the mentioned method into a path continuation scheme. With this approach, it is possible to track jump phenomena or the influence of parameter variations even in case of narrow band excitation. The results of the performed calculations are the stochastic moments, i.e. mean value and variance.

Transient Temperature Involving Oscillatory Heat Source With Application in Fretting Contact

2007 ◽  
Vol 129 (3) ◽  
pp. 517-527 ◽  
Author(s):  
Jun Wen ◽  
M. M. Khonsari
Keyword(s):  
Heat Source ◽  
Oscillation Amplitude ◽  
The Body ◽  
Transient Temperature ◽  
Dimensionless Frequency ◽  
Heat Sources ◽  
Infinite Body ◽  
Fitting Method ◽  
Wide Range ◽  
Analytical Expressions

An analytical approach for treating problems involving oscillatory heat source is presented. The transient temperature profile involving circular, rectangular, and parabolic heat sources undergoing oscillatory motion on a semi-infinite body is determined by integrating the instantaneous solution for a point heat source throughout the area where the heat source acts with an assumption that the body takes all the heat. An efficient algorithm for solving the governing equations is developed. The results of a series simulations are presented, covering a wide range of operating parameters including a new dimensionless frequency ω¯=ωl2∕4α and the dimensionless oscillation amplitude A¯=A∕l, whose product can be interpreted as the Peclet number involving oscillatory heat source, Pe=ω¯A¯. Application of the present method to fretting contact is presented. The predicted temperature is in good agreement with published literature. Furthermore, analytical expressions for predicting the maximum surface temperature for different heat sources are provided by a surface-fitting method based on an extensive number of simulations.

scholarly journals On the spectrum of vertically propagating gravity waves generated by a transient heat source

2004 ◽  
Vol 4 (1) ◽  
pp. 1063-1090 ◽  
Author(s):  
M. J. Alexander ◽  
J. R. Holton
Keyword(s):  
Heat Source ◽  
Gravity Waves ◽  
High Frequency ◽  
Convective Heating ◽  
Frequency Spectra ◽  
Wide Range ◽  
Frequency Components ◽  
High Frequency Waves ◽  
Vertically Propagating ◽  
Group Velocities

Abstract. It is commonly believed that cumulus convection preferentially generates gravity waves with tropospheric vertical wavelengths approximately twice the depth of the convective heating. Individual cumulonimbus, however, act as short term transient heat sources (duration 10 to 30 min). Gravity waves generated by such sources have broad frequency spectra and a wide range of vertical scales. The high-frequency components tend to have vertical wavelengths much greater than twice the depth of the heating. Such waves have large vertical group velocities, and are only observed for a short duration and at short horizontal distances from the convective source. At longer times and longer distances from the source the dominant wave components have short vertical wavelengths and much slower group velocities, and thus are more likely to be observed even though their contribution to the momentum flux in the upper stratosphere and mesosphere may be less than that of the high frequency waves. These properties of convectively generated waves are illustrated by a linear numerical model for the wave response to a specified transient heat source. The wave characteristics are documented through Fourier and Wavelet analysis, and implications for observing systems are discussed.

scholarly journals Passive control of instabilities in combustion systems with heat exchanger

2017 ◽  
Vol 10 (4) ◽  
pp. 362-379 ◽  
Author(s):  
Aswathy Surendran ◽  
Maria A Heckl ◽  
Naseh Hosseini ◽  
Omke Jan Teerling
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Transfer Function ◽  
Heat Source ◽  
Passive Control ◽  
Time Lag ◽  
Acoustic Scattering ◽  
Resonant Mode ◽  
Combustion Instabilities ◽  
Wide Range

One of the major concerns in the operability of power generation systems is their susceptibility to combustion instabilities. In this work, we explore whether a heat exchanger, an integral component of a domestic boiler, can be made to act as a passive controller that suppresses combustion instabilities. The combustor is modelled as a quarter-wave resonator (1-D, open at one end, closed at the other) with a compact heat source inside, which is modelled by a time-lag law. The heat exchanger is modelled as an array of tubes with bias flow and is placed near the closed end of the resonator, causing it to behave like a cavity-backed slit plate: an effective acoustic absorber. For simplicity and ease of analysis, we treat the physical processes of heat transfer and acoustic scattering occurring at the heat exchanger as two individual processes separated by an infinitesimal distance. The aeroacoustic response of the tube array is modelled using a quasi-steady approach and the heat transfer across the heat exchanger is modelled by assuming it to be a heat sink. Unsteady numerical simulations were carried out to obtain the heat exchanger transfer function, which is the response of the heat transfer at heat exchanger to upstream velocity perturbations. Combining the aeroacoustic response and the heat exchanger transfer function, in the limit of the distance between these processes tending to zero, gives the net influence of the heat exchanger. Other parameters of interest are the heat source location and the cavity length (the distance between the tube array and the closed end). We then construct stability maps for the first resonant mode of the aforementioned combustor configuration, for various parameter combinations. Our model predicts that stability can be achieved for a wide range of parameters.

scholarly journals An Efficient Time Reversal Method for Lamb Wave-Based Baseline-Free Damage Detection in Composite Laminates

2018 ◽  
Vol 9 (1) ◽  
pp. 11 ◽  
Author(s):  
Liping Huang ◽  
Junmin Du ◽  
Feiyu Chen ◽  
Liang Zeng
Keyword(s):  
Damage Detection ◽  
Time Reversal ◽  
Lamb Wave ◽  
Composite Laminates ◽  
Narrow Band ◽  
Great Influence ◽  
Time Intervals ◽  
Wide Range ◽  
Reconstructed Signal ◽  
Short Time

Time reversal (TR) concept is widely used for Lamb wave-based damage detection. However, the time reversal process (TRP) faces the challenge that it requires two actuating-sensing steps and requires the extraction of re-emitted and reconstructed waveforms. In this study, the effects of the two extracted components on the performance of TRP are studied experimentally. The results show that the two time intervals, in which the waveforms are extracted, have great influence on the accuracy of damage detection of the time reversal method (TRM). What is more, it requires a large number of experiments to determine these two time intervals. Therefore, this paper proposed an efficient time reversal method (ETRM). Firstly, a broadband excitation is applied to obtain response at a wide range of frequencies, and ridge reconstruction based on inverse short-time Fourier transform is applied to extract desired mode components from the broadband response. Subsequently, deconvolution is used to extract narrow-band reconstructed signal. In this method, the reconstructed signal can be easily obtained without determining the two time intervals. Besides, the reconstructed signals related to a series of different excitations could be obtained through only one actuating-sensing step. Finally, the effectiveness of the ETRM for damage detection in composite laminates is verified through experiments.

scholarly journals Wide-Range Tunable Narrow Band-Stop Filter Based on Bilayer Graphene in the Mid-Infrared Region

2020 ◽  
Vol 12 (4) ◽  
pp. 1-9
Author(s):  
Yindi Wang ◽  
Hongxia Liu ◽  
Shulong Wang ◽  
Ming Cai
Keyword(s):  
Narrow Band ◽  
Infrared Region ◽  
Bilayer Graphene ◽  
Mid Infrared ◽  
Wide Range ◽  
Band Stop Filter
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