The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Huaichun Zhou - One of the best experts on this subject based on the ideXlab platform.
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experiments investigation on 2d distribution of soot temperature and volume fraction by image processing of visible Radiation
Applied Thermal Engineering, 2017Co-Authors: Shu Zheng, Huaichun ZhouAbstract:Abstract A simple diagnostics method was presented that uses a low-cost camera to simultaneously reconstruct 2D distributions of flame temperature and soot concentration in laminar diffusion axisymmetric flames. A Manta G-504 camera with one million effective pixels was utilized for data collection, equipped with the lens type Computar TEC-55 with one customized double-bandpass filter mounted on front of the camera. This setup was used to obtain 615 and 517 nm Monochromatic Radiation flame images. Firstly, the spectral response spectrums and the directional emissive powers of the measurement system were calibrated. Then, the Tikhonov regularization method was used for inversing the spectral emission source term. Secondly, neglecting the self-absorption effect, the local temperature T ( l ) and soot concentration f v ( l ) could be calculated based on the ratio method. Finally, re-considering the self-absorption effect, the iterative computational method was implemented to update the calculated temperature T ( l ) and soot concentration f v ( l ) . The resulting measurements reported in this study are in good alignment with the LII method and emission spectrum method. The proposed diagnostic method was found to be capable of simultaneous reconstruction of 2D distribution of soot temperature and concentration.
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simultaneous measurement of three dimensional temperature distributions and radiative properties based on Radiation image processing technology in a gas fired pilot tubular furnace
Heat Transfer Engineering, 2014Co-Authors: Qiang Cheng, Huaichun Zhou, Xiangyu Zhang, Zhichao Wang, Song ShaoAbstract:An on-line three-dimensional temperature measurement experiment was carried out in a gas-fired pilot tubular furnace. Four flame image detectors were utilized to obtain two (red and green) Monochromatic Radiation intensity distributions, which can be calculated by the DRESOR method based on the Radiation image processing technology. Then a revised Tikhonov regularization method was developed to reconstruct three-dimensional temperature distributions from the green Monochromatic radiative intensity. Meanwhile, a Newton method combined with a least-squares method was used to simultaneously reconstruct radiative properties from the red one. The two calculation procedures were performed alternately, forming an iterative algorithm to a simultaneous reconstruction of temperature and radiative properties. The reconstructed temperatures agreed well with those measured by thermocouples for different cases with different calorific values and components of gas. The largest relative error was less than 3%, which vali...
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experimental investigations on visualization of three dimensional temperature distributions in a large scale pulverized coal fired boiler furnace
Proceedings of the Combustion Institute, 2005Co-Authors: Huaichun Zhou, Zhiwei Jiang, Chun Lou, Qiang Cheng, Benyuan Huang, Zhenlin PeiAbstract:Abstract By using a novel flame image processing technique, the 3-D temperature distributions of combustion in the pulverized-coal-fired boiler furnace of a 200 MW power generation unit were visualized experimentally. With the assumption of gray Radiation, multiple color flame image detectors were used to capture approximately Monochromatic Radiation intensity images under the visible wavelengths of red (R), green (G), and blue (B), and a blackbody furnace was used to calibrate the color images. A way to calculate the Radiation intensity using the Monte Carlo method was used to establish the relationship between the Radiation flame images and the 3-D temperature distribution inside the furnace, given the radiative parameters such as the absorption and scattering coefficients of the combustion medium. A modified Tikhonov regularization method was used to reconstruct the 3-D temperature distribution from the 2-D flame temperature images transformed from the color flame images. Eight flame image detectors were mounted close to the four corners in four layers in different heights in the furnace, the 3-D temperature distribution in 1200 discrete meshes in 12 layers along the height of the furnace was reconstructed from the eight flame images, and the visualization result was updated within 5 s. The errors between some local temperatures visualized by the present system with those measured by a suction thermocouple were within ±5%, showing applicability of the method. On-line monitoring results demonstrated that the average temperature inside the furnace changed directly proportionally with the load of the unit. The preliminary results show that this technology will be useful for the combustion diagnosis and control in coal-fired power generation plants.
Mark D Sobsey - One of the best experts on this subject based on the ideXlab platform.
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Survival of prototype strains of somatic coliphage families in environmental waters and when exposed to UV low-pressure Monochromatic Radiation or heat.
Water Research, 2011Co-Authors: Mark D SobseyAbstract:Abstract The potential use of specific somatic coliphage taxonomic groups as viral indicators based on their persistence and prevalence in water was investigated. Representative type strains of the 4 major somatic coliphage taxonomic groups were seeded into reagent water and an ambient surface water source of drinking water and the survival of the added phages was measured over 90 days at temperatures of 23–25 and 4 °C. Microviridae (type strain PhiX174), Siphoviridae (type strain Lambda), and Myoviridae (type strain T4) viruses were the most persistent in water at the temperatures tested. The Microviridae (type strain PhiX174) and the Siphoviridae (type strain Lambda) were the most resistant viruses to UV Radiation and the Myoviridae (type strain T4) and the Microviridae (type strain PhiX174) were the most resistant viruses to heat. Based on their greater persistence in water over time and their relative resistance to heat and/or UV Radiation, the Myoviridae (type strain T4), the Microviridae (type strain PhiX174), and the Siphoviridae (type strain Lambda) were the preferred candidate somatic coliphages as fecal indicator viruses in water, with the Microviridae (type strain PhiX174) the most resistant to these conditions overall.
Karel Saksl - One of the best experts on this subject based on the ideXlab platform.
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role of heat accumulation in the multi shot damage of silicon irradiated with femtosecond xuv pulses at a 1 mhz repetition rate
Optics Express, 2016Co-Authors: R Sobierajski, Iwanna Jacyna, Piotr Dluzewski, M T Klepka, D Klinger, J B Pelka, T Burian, V Hajkova, L Juha, Karel SakslAbstract:The role played by heat accumulation in multi-shot damage of silicon was studied. Bulk silicon samples were exposed to intense XUV Monochromatic Radiation of a 13.5 nm wavelength in a series of 400 femtosecond pulses, repeated with a 1 MHz rate (pulse trains) at the FLASH facility in Hamburg. The observed surface morphological and structural modifications are formed as a result of sample surface melting. Modifications are threshold dependent on the mean fluence of the incident pulse train, with all threshold values in the range of approximately 36-40 mJ/cm2. Experimental data is supported by a theoretical model described by the heat diffusion equation. The threshold for reaching the melting temperature (45 mJ/cm2) and liquid state (54 mJ/cm2), estimated from this model, is in accordance with experimental values within measurement error. The model indicates a significant role of heat accumulation in surface modification processes.
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role of heat accumulation in the multi shot damage of silicon irradiated with femtosecond xuv pulses at a 1 mhz repetition rate
Optics Express, 2016Co-Authors: R Sobierajski, Iwanna Jacyna, Piotr Dluzewski, M T Klepka, D Klinger, J B Pelka, T Burian, V Hajkova, L Juha, Karel SakslAbstract:The role played by heat accumulation in multi-shot damage of silicon was studied. Bulk silicon samples were exposed to intense XUV Monochromatic Radiation of a 13.5 nm wavelength in a series of 400 femtosecond pulses, repeated with a 1 MHz rate (pulse trains) at the FLASH facility in Hamburg. The observed surface morphological and structural modifications are formed as a result of sample surface melting. Modifications are threshold dependent on the mean fluence of the incident pulse train, with all threshold values in the range of approximately 36-40 mJ/cm2. Experimental data is supported by a theoretical model described by the heat diffusion equation. The threshold for reaching the melting temperature (45 mJ/cm2) and liquid state (54 mJ/cm2), estimated from this model, is in accordance with experimental values within measurement error. The model indicates a significant role of heat accumulation in surface modification processes.
R Sobierajski - One of the best experts on this subject based on the ideXlab platform.
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role of heat accumulation in the multi shot damage of silicon irradiated with femtosecond xuv pulses at a 1 mhz repetition rate
Optics Express, 2016Co-Authors: R Sobierajski, Iwanna Jacyna, Piotr Dluzewski, M T Klepka, D Klinger, J B Pelka, T Burian, V Hajkova, L Juha, Karel SakslAbstract:The role played by heat accumulation in multi-shot damage of silicon was studied. Bulk silicon samples were exposed to intense XUV Monochromatic Radiation of a 13.5 nm wavelength in a series of 400 femtosecond pulses, repeated with a 1 MHz rate (pulse trains) at the FLASH facility in Hamburg. The observed surface morphological and structural modifications are formed as a result of sample surface melting. Modifications are threshold dependent on the mean fluence of the incident pulse train, with all threshold values in the range of approximately 36-40 mJ/cm2. Experimental data is supported by a theoretical model described by the heat diffusion equation. The threshold for reaching the melting temperature (45 mJ/cm2) and liquid state (54 mJ/cm2), estimated from this model, is in accordance with experimental values within measurement error. The model indicates a significant role of heat accumulation in surface modification processes.
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role of heat accumulation in the multi shot damage of silicon irradiated with femtosecond xuv pulses at a 1 mhz repetition rate
Optics Express, 2016Co-Authors: R Sobierajski, Iwanna Jacyna, Piotr Dluzewski, M T Klepka, D Klinger, J B Pelka, T Burian, V Hajkova, L Juha, Karel SakslAbstract:The role played by heat accumulation in multi-shot damage of silicon was studied. Bulk silicon samples were exposed to intense XUV Monochromatic Radiation of a 13.5 nm wavelength in a series of 400 femtosecond pulses, repeated with a 1 MHz rate (pulse trains) at the FLASH facility in Hamburg. The observed surface morphological and structural modifications are formed as a result of sample surface melting. Modifications are threshold dependent on the mean fluence of the incident pulse train, with all threshold values in the range of approximately 36-40 mJ/cm2. Experimental data is supported by a theoretical model described by the heat diffusion equation. The threshold for reaching the melting temperature (45 mJ/cm2) and liquid state (54 mJ/cm2), estimated from this model, is in accordance with experimental values within measurement error. The model indicates a significant role of heat accumulation in surface modification processes.
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damage threshold of inorganic solids under free electron laser irRadiation at 32 5 nm wavelength
Applied Physics Letters, 2007Co-Authors: Stefan P Hauriege, R Sobierajski, J B Pelka, R A London, Richard M Bionta, Mark A Mckernan, Sherry L Baker, J Krzywinski, R Nietubyc, M JurekAbstract:We exposed samples of B4C, amorphous C, chemical-vapor-deposition (CVD)-diamond C, Si, and SiC to single 25 fs-long pulses of 32.5 nm free-electron-laser Radiation at fluences of up to 2.2 J/cm{sup 2}. The samples were chosen as candidate materials for x-ray free electron laser (XFEL) optics. We found that the threshold for surface-damage is on the order of the fluence required for thermal melting. For larger fluences, the crater depths correspond to temperatures on the order of the critical temperature, suggesting that the craters are formed by two-phase vaporization [1]. XFELs have the promise of producing extremely high-intensity ultrashort pulses of coherent, Monochromatic Radiation in the 1 to 10 keV regime. The expected high output fluence and short pulse duration pose significant challenges to the optical components, including Radiation damage. It has not been possible to obtain direct experimental verification of the expected damage thresholds since appropriate x-ray sources are not yet available. FLASH has allowed us to study the interaction of high-fluence short-duration photon pulses with materials at the shortest wavelength possible to date. With these experiments, we have come closer to the extreme conditions expected in XFEL-matter interaction scenarios than previously possible.
Biswanath Mallik - One of the best experts on this subject based on the ideXlab platform.
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spectroscopic investigation on the photoinduced charge transfer between ferrocene and chloroform molecules confined in a poly methyl methacrylate thin film
Solid State Communications, 1999Co-Authors: Alfazuddin Thander, Biswanath MallikAbstract:Abstract The changes in the electronic absorption spectra (UV–Vis) of ferrocene-doped poly(methylmethacrylate) (PMMA) thin films, containing chloroform molecules as impurities, after photoexcitations in air as well as in dry nitrogen atmosphere have been investigated. Photoexcitations have been made by Monochromatic Radiation (using a Xe-lamp source and a monochromator) at an interval of few nanometers in the spectral range 210–750 nm. The changes in spectra after photoexcitation have been studied as a function of: (i) time (duration) of photoexcitation; (ii) amount of ferrocene in the film; and (iii) amount of chloroform molecules in the film. The analysis of the results has indicated the occurrence of photoinduced charge-transfer between ferrocene and chloroform molecules confined in the PMMA thin films. The action spectrum of photoinduced changes has shown one peak in the UV region at about 261 nm. Ferrocene-doped PMMA thin films containing chloroform molecules are expected to be useful in the photoelectrochemical devices.