The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Richard A Beier - One of the best experts on this subject based on the ideXlab platform.
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analysis of thermal response tests on boreholes with controlled inlet temperature versus controlled Heat Input Rate
Geothermics, 2021Co-Authors: Richard A BeierAbstract:Abstract Thermal response tests (TRT) are performed on borehole Heat exchangers to estimate design properties needed when the boreholes are coupled to Heat pumps. In conventional TRTs the Heat injection or extraction Rate from an external Heater or Heat pump is controlled to be nearly constant. More recently some investigators have conducted TRTs while controlling the inlet fluid temperature to be nearly constant. This paper develops computationally efficient Heat transfer models that match measured transient temperature curves throughout the entire duration for both types of tests. The models include variable Heat Rates, thermal storage of the borehole fluid and the different properties between the grout and ground. The models are combined with parameter estimation methods and applied to both types of data sets from the same borehole. An uncertainty analysis indicates the models estimate ground thermal conductivity and borehole thermal resistance with approximately the same uncertainty for both types of tests.
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Deconvolution and convolution methods for thermal response tests on borehole Heat exchangers
Geothermics, 2020Co-Authors: Richard A BeierAbstract:Abstract A thermal response test (TRT) on a borehole evaluates ground and borehole properties, which are needed in the design of borehole fields for ground source Heat pump systems. Variation in the Heat Input Rate during a TRT complicates the data analysis, when the electrical power to the test equipment is unintentionally interrupted, or other unwanted changes in the power supply occur. Then, the measured transient temperature curve is a convolution of the varying Rate and the constant-unit-Rate response function. A deconvolution method has been developed to determine the borehole temperature response that would have occurred if the Heat Input Rate would have remained fixed. The deconvolution technique and the conventional temporal superposition method are validated with TRT data sets with interruptions carried out in a laboratory sandbox. The methods are also applied to field TRT data sets. The deconvolution method has the advantage of generating a smoothed temperature derivative curve, which is used to identify three distinct time periods during a TRT to enhance the analysis.
J. Singh - One of the best experts on this subject based on the ideXlab platform.
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Spectroscopic Observation of Coronal Waves
Solar Physics, 2002Co-Authors: T. Sakurai, K. Ichimoto, K.p. Raju, J. SinghAbstract:A time sequence over 80 min of coronal green-line spectra was obtained with a corona- graph at the Norikura Solar Observatory. Doppler velocities, line intensities, and line widths were derived through fitting a single Gaussian to the observed line profiles. Coronal waves have been clearly detected in the Doppler velocity data. The Fourier analysis shows powers in a 1–3 mHz range, and in higher frequencies (5–7 mHz) at localized regions. The propagation speed of the waves was estimated by correlation analysis. The line intensity and line width did not show clear oscillations, but their phase relationship with the Doppler velocity indicates propagating waves rather than standing waves. The existence of Alfvén waves whose speed is 500 km s^−1 or faster is possible but inconclusive, while the existence of slower waves (of the order of 100 km s^−1, possibly sound waves) is evident. The energy carried by the detected sound waves is far smaller than the required Heat Input Rate to the quiet corona.
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Spectroscopic Observation of Coronal Waves
Solar Physics, 2002Co-Authors: T. Sakurai, K. Ichimoto, K.p. Raju, J. SinghAbstract:A time sequence over 80 min of coronal green-line spectra was obtained with a corona- graph at the Norikura Solar Observatory. Doppler velocities, line intensities, and line widths were derived through fitting a single Gaussian to the observed line profiles. Coronal waves have been clearly detected in the Doppler velocity data. The Fourier analysis shows powers in a 1–3 mHz range, and in higher frequencies (5–7 mHz) at localized regions. The propagation speed of the waves was estimated by correlation analysis. The line intensity and line width did not show clear oscillations, but their phase relationship with the Doppler velocity indicates propagating waves rather than standing waves. The existence of Alfven waves whose speed is 500 km s−1 or faster is possible but inconclusive, while the existence of slower waves (of the order of 100 km s−1, possibly sound waves) is evident. The energy carried by the detected sound waves is far smaller than the required Heat Input Rate to the quiet corona.
Wei Xiao-feng - One of the best experts on this subject based on the ideXlab platform.
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The Determination of Burner Heat Input Rate Required for Welding Process of Thick Steel Pipe
Energy technology, 2007Co-Authors: Wei Xiao-fengAbstract:Numeric simulation was performed for welding process of thick steel pipes to determine the required Heat Input Rate.All temperature-rising procedure was simulated.The results can be helpful to calculate the efficiency of Heating process and to guide energy conservation.
S. Lulić - One of the best experts on this subject based on the ideXlab platform.
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Formation of coronal MHD shock waves – II. The Pressure Pulse Mechanism
Solar Physics, 2000Co-Authors: B. Vršnak, S. LulićAbstract:The ignition of coronal shock waves by flares is investigated. It is assumed that an explosive expansion of the source region caused by impulsive Heating geneRates a fast-mode MHD blast wave which subsequently transforms into a shock wave. The solutions of 1-D MHD equations for the flaring region and for the external region are matched at their boundary. The obtained results show under what conditions flares can ignite shock waves that excite the metric type II bursts. The Heat Input Rate per unit mass has to be sufficiently high and the preflare value of the plasma parameter β in the flaring region has to be larger than β_0 ^crit. The critical values depend on the flare dimensions and impulsiveness. Larger and more impulsive flares are more effective in generating type II bursts. Shock waves of a higher Mach number require a higher preflare value of β and a more powerful Heating per unit mass. The results demonstRate why only a small fraction of flares is associated with type II bursts and why the association Rate increases with the flare importance.
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Formation of coronal MHD shock waves - II. The Pressure Pulse Mechanism
Solar Physics, 2000Co-Authors: B. Vršnak, S. LulićAbstract:The ignition of coronal shock waves by flares is investigated. It is assumed that an explosive expansion of the source region caused by impulsive Heating geneRates a fast-mode MHD blast wave which subsequently transforms into a shock wave. The solutions of 1-D MHD equations for the flaring region and for the external region are matched at their boundary. The obtained results show under what conditions flares can ignite shock waves that excite the metric type II bursts. The Heat Input Rate per unit mass has to be sufficiently high and the preflare value of the plasma parameter β in the flaring region has to be larger than β0crit. The critical values depend on the flare dimensions and impulsiveness. Larger and more impulsive flares are more effective in generating type II bursts. Shock waves of a higher Mach number require a higher preflare value of β and a more powerful Heating per unit mass. The results demonstRate why only a small fraction of flares is associated with type II bursts and why the association Rate increases with the flare importance.
R. Fenn - One of the best experts on this subject based on the ideXlab platform.
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The control of the thin-plate welds geometry and microstructure
Journal of Materials Processing Technology, 1997Co-Authors: Winco K.c. Yung, Bun Lee, B. Ralph, R. FennAbstract:Abstract In this paper, an attempt was made to employ conventional shear waves to investigate the quality of thin-plate welds. A quantitative measure of the weld pool width was suggested, and the alignment as well as the symmetry of the pool about the weld line is indicated without micro-sectioning the weld. Also, the relative grain sizes around the weld's fusion zone could be indicated by their corresponding ultrasonic attenuation. Mathematical relationships of ultrasonic attenuation with welding current and Heat Input Rate were established.
