The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform
Tetsuya Takemi - One of the best experts on this subject based on the ideXlab platform.
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environmental stability control of the Intensity of squall Lines under low level shear conditions
Journal of Geophysical Research, 2007Co-Authors: Tetsuya TakemiAbstract:[1] The environment for the development and evolution of Linearly organized convective systems, i.e., squall Lines is diverse for their existence in various climate regions. Understanding the behavior of squall Lines under various environmental conditions is required for diagnosing and forecasting the development and Intensity of the convective systems. The present study investigates the effects of environmental static stability on the squall-Line Intensity by conducting a systematic series of idealized cloud-resolving simulations of squall Lines that develop in Line-perpendicular, low-level westerly shear. Changing the temperature lapse rate with convective available potential energy (CAPE) being unchanged, we showed that the environmental stability in a convectively unstable layer well describes the Intensity of the simulated squall Lines. A less stable stability is favorable for generating stronger convective systems. The amount of CAPE does not account for the difference in the squall-Line Intensity in different temperature environments. An environment with a less static stability leads to the development of stronger cold pool, which will strongly controls the scale and strength of convective updrafts, the Intensity of tropospheric overturning, and thus the organization and Intensity of squall Lines. The CAPE value can only be a good measure for diagnosing the development and Intensity of the convective systems so long as the environmental static stability is identical. The static stability is a controlling parameter in determining the Intensity of squall Lines.
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a sensitivity of squall Line Intensity to environmental static stability under various shear and moisture conditions
Atmospheric Research, 2007Co-Authors: Tetsuya TakemiAbstract:Abstract Squall Lines develop in various climate regions having diverse environmental profiles of wind shear, moisture, and temperature. In order to explore the sensitivity of squall Lines to these environmental profiles, we have performed an extensive set of numerical simulations under various shear and moisture conditions in midlatitude-continental and tropical–oceanic temperature environments. From the results of the sensitivity simulations and the analyses of the environmental parameters, it is found that the static stability in a convectively unstable layer is of primary importance in determining the strength of squall Lines. Under temperature environments having the same static stability, convective available potential energy (CAPE) and precipitable water content (PWC) well describe the squall-Line Intensity. Vertical shear also plays an important role in determining the squall-Line structure as well as the Intensity through the interaction with surface cold pool. The combination of the static stability in a convectively unstable layer, CAPE, and PWC should be examined in diagnosing the Intensity of squall Lines that develop with an optimal shear for their environment.
Risa H Wechsler - One of the best experts on this subject based on the ideXlab platform.
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cross correlating carbon monoxide Line Intensity maps with spectroscopic and photometric galaxy surveys
The Astrophysical Journal, 2019Co-Authors: Dongwoo T Chung, Patrick C Breysse, M P Viero, S E Church, Risa H Wechsler, Marcelo A Alvarez, Richard J Bond, Kieran Cleary, H K Eriksen, Marie K FossAbstract:Line-Intensity mapping is an emerging field of observational work, with strong potential to fit into a larger effort to probe large-scale structure and small-scale astrophysical phenomena using multiple complementary tracers. Taking full advantage of such complementarity means, in part, undertaking Line-Intensity surveys with galaxy surveys in mind. We consider the potential for detection of a cross-correlation signal between COMAP and blind surveys based on photometric redshifts (as in COSMOS) or based on spectroscopic data (as with the HETDEX survey of Lyα emitters). We find that obtaining σ_z (1+z) ≲ 0.003 accuracy in redshifts and ≳10^(−4) sources per Mpc^3 with spectroscopic redshift determination should enable a CO-galaxy cross spectrum detection significance at least twice that of the CO auto spectrum. Either a future targeted spectroscopic survey or a blind survey like HETDEX may be able to meet both of these requirements.
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forecasting c ii Line Intensity mapping measurements between the end of reionization and the epoch of galaxy assembly
arXiv: Astrophysics of Galaxies, 2018Co-Authors: Dongwoo T Chung, S E Church, Risa H Wechsler, Marco P VieroAbstract:We combine recent simulation work on the SFR--[C II] correlation at high redshift with empirical modeling of the galaxy--halo connection (via UniverseMachine) to forecast [C II] auto power spectra from $z\sim4$ to $z\sim8$. We compare these to sensitivities realistically expected from various instruments expected to come on-Line in the next decade. If the predictions of our model are correct, [C II] should be detectable up to $z\sim6$ in this generation of surveys, but detecting [C II] past the end of reionization will require a generational leap in Line-Intensity survey capabilities.
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on estimation of contamination from hydrogen cyanide in carbon monoxide Line Intensity mapping
The Astrophysical Journal, 2017Co-Authors: Dongwoo T Chung, M P Viero, S E Church, Risa H Wechsler, Tony Y LiAbstract:Line-Intensity mapping surveys probe large-scale structure through spatial variations in molecular Line emission from a population of unresolved cosmological sources. Future such surveys of carbon monoxide Line emission, specifically the CO(1-0) Line, face potential contamination from a disjointed population of sources emitting in a hydrogen cyanide emission Line, HCN(1-0). This paper explores the potential range of the strength of HCN emission and its effect on the CO auto power spectrum, using simulations with an empirical model of the CO/HCN–halo connection. We find that effects on the observed CO power spectrum depend on modeling assumptions but are very small for our fiducial model, which is based on current understanding of the galaxy–halo connection. Given the fiducial model, we expect the bias in overall CO detection significance due to HCN to be less than 1%.
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on estimation of contamination from hydrogen cyanide in carbon monoxide Line Intensity mapping
arXiv: Astrophysics of Galaxies, 2017Co-Authors: Dongwoo T Chung, M P Viero, S E Church, Risa H Wechsler, Tony Y LiAbstract:Line-Intensity mapping surveys probe large-scale structure through spatial variations in molecular Line emission from a population of unresolved cosmological sources. Future such surveys of carbon monoxide Line emission (specifically the CO(1-0) Line) face potential contamination from a disjoint population of sources emitting in a hydrogen cyanide emission Line, HCN(1-0). This paper explores the potential range of the strength of HCN emission and its effect on the CO auto power spectrum, using simulations with an empirical model of the CO/HCN--halo connection. We find that effects on the observed CO power spectrum vary with modeling approaches but are very small for our fiducial model, with the undesirable boost in overall CO detection significance due to HCN expected to be less than 1%.
Jyoti Mazumder - One of the best experts on this subject based on the ideXlab platform.
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Real-Time Composition Monitoring Using Support Vector Regression of Laser-Induced Plasma for Laser Additive Manufacturing
IEEE Transactions on Industrial Electronics, 2016Co-Authors: Lijun Song, Wenkang Huang, Xu Han, Jyoti MazumderAbstract:Laser additive manufacturing has gained widespread adoption in recent years. However, process diagnosis and process control lag behind the progresses of other key technologies, which makes the product quality control a challenging problem. This work proposes an operating parameter conditioned support vector regression (SVR) method that uses processing parameter conditioned kernel function to achieve a processing parameter independent in-situ composition prediction. Two different features of laser-induced plasma, spectral Line-Intensity-ratio and both spectral Line-Intensity-ratio and spectral integrated Intensity, were used to train the SVR. Composition measurements using calibration curve method, partial least square regression, and artificial neural networks are also performed for comparison. The results show that the SVR with both spectral Line-Intensity-ratio and spectral integrated Intensity as inputs has the best performance due to Linearly separable point clusters in the high dimensional space. Laser power independent composition prediction is achieved and real-time composition predictions are validated. It is proved that the operating parameter conditioned SVR provides a more accurate, a more universal and an operating parameter independent prediction. Moreover, operating parameter conditioned SVR provides a potential data-driven-based approach for real-time composition monitoring of laser additive manufacturing process.
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Real Time Cr Measurement Using Optical Emission Spectroscopy During Direct Metal Deposition Process
IEEE Sensors Journal, 2012Co-Authors: Lijun Song, Jyoti MazumderAbstract:Real-time chromium composition analysis during direct metal deposition of pure chromium and H13 tool steel materials was performed using optical emission spectroscopy of the laser-induced plasma. Four second-order polynomial calibration curves were constructed using spectral Line Intensity ratios between two neutral chromium Lines and two neutral iron Lines. Second-order polynomial calibration curves were also formed using plasma temperature and electron density. The plasma temperature was obtained using Boltzmann plot of nine neutral iron Lines between 370 nm and 390 nm. The electron density was estimated using Stark broadening of Fe-I Line at 426.047 nm. Chromium concentration in the range from 10% to 60% was measured using these calibration curves in real-time during synthesis process and verified from energy dispersive X-ray spectroscopy of the manufactured parts. The measurement from Line Intensity ratio calibration curve is more accurate and has less standard deviation than that from plasma temperature and electron density calibration curves. The accuracy of the measured chromium concentration is within 2.78% in at.% and the average resolution of the measurement is around 5.12% in at.% from the averaged values of four Line Intensity ratio calibration curves.
Dongwoo T Chung - One of the best experts on this subject based on the ideXlab platform.
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a partial inventory of observational anisotropies in single dish Line Intensity mapping
The Astrophysical Journal, 2019Co-Authors: Dongwoo T ChungAbstract:Line-Intensity mapping, being an imperfect observation of the Line-Intensity field in a cosmological volume, will be subject to various anisotropies introduced in observation. Existing literature in the context of CO and [C II] Line-Intensity mapping often predicts only the real-space, spherically averaged Line-Intensity power spectrum, with some works considering anisotropies while examining projection of interloper emission. We explicitly consider a simplified picture of redshift-space distortions and instrumental effects due to limited resolution, and how these distort an isotropic Line-Intensity signal in real space and introduce strong apparent anisotropies. The results suggest that while signal loss due to limited instrumental resolution is unavoidable, measuring the quadrupole power spectrum in addition to the monopole would still break parameter degeneracies present in monopole-only constraints, even without a measurement of the full anisotropic power spectrum.
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cross correlating carbon monoxide Line Intensity maps with spectroscopic and photometric galaxy surveys
The Astrophysical Journal, 2019Co-Authors: Dongwoo T Chung, Patrick C Breysse, M P Viero, S E Church, Risa H Wechsler, Marcelo A Alvarez, Richard J Bond, Kieran Cleary, H K Eriksen, Marie K FossAbstract:Line-Intensity mapping is an emerging field of observational work, with strong potential to fit into a larger effort to probe large-scale structure and small-scale astrophysical phenomena using multiple complementary tracers. Taking full advantage of such complementarity means, in part, undertaking Line-Intensity surveys with galaxy surveys in mind. We consider the potential for detection of a cross-correlation signal between COMAP and blind surveys based on photometric redshifts (as in COSMOS) or based on spectroscopic data (as with the HETDEX survey of Lyα emitters). We find that obtaining σ_z (1+z) ≲ 0.003 accuracy in redshifts and ≳10^(−4) sources per Mpc^3 with spectroscopic redshift determination should enable a CO-galaxy cross spectrum detection significance at least twice that of the CO auto spectrum. Either a future targeted spectroscopic survey or a blind survey like HETDEX may be able to meet both of these requirements.
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forecasting c ii Line Intensity mapping measurements between the end of reionization and the epoch of galaxy assembly
arXiv: Astrophysics of Galaxies, 2018Co-Authors: Dongwoo T Chung, S E Church, Risa H Wechsler, Marco P VieroAbstract:We combine recent simulation work on the SFR--[C II] correlation at high redshift with empirical modeling of the galaxy--halo connection (via UniverseMachine) to forecast [C II] auto power spectra from $z\sim4$ to $z\sim8$. We compare these to sensitivities realistically expected from various instruments expected to come on-Line in the next decade. If the predictions of our model are correct, [C II] should be detectable up to $z\sim6$ in this generation of surveys, but detecting [C II] past the end of reionization will require a generational leap in Line-Intensity survey capabilities.
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on estimation of contamination from hydrogen cyanide in carbon monoxide Line Intensity mapping
The Astrophysical Journal, 2017Co-Authors: Dongwoo T Chung, M P Viero, S E Church, Risa H Wechsler, Tony Y LiAbstract:Line-Intensity mapping surveys probe large-scale structure through spatial variations in molecular Line emission from a population of unresolved cosmological sources. Future such surveys of carbon monoxide Line emission, specifically the CO(1-0) Line, face potential contamination from a disjointed population of sources emitting in a hydrogen cyanide emission Line, HCN(1-0). This paper explores the potential range of the strength of HCN emission and its effect on the CO auto power spectrum, using simulations with an empirical model of the CO/HCN–halo connection. We find that effects on the observed CO power spectrum depend on modeling assumptions but are very small for our fiducial model, which is based on current understanding of the galaxy–halo connection. Given the fiducial model, we expect the bias in overall CO detection significance due to HCN to be less than 1%.
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on estimation of contamination from hydrogen cyanide in carbon monoxide Line Intensity mapping
arXiv: Astrophysics of Galaxies, 2017Co-Authors: Dongwoo T Chung, M P Viero, S E Church, Risa H Wechsler, Tony Y LiAbstract:Line-Intensity mapping surveys probe large-scale structure through spatial variations in molecular Line emission from a population of unresolved cosmological sources. Future such surveys of carbon monoxide Line emission (specifically the CO(1-0) Line) face potential contamination from a disjoint population of sources emitting in a hydrogen cyanide emission Line, HCN(1-0). This paper explores the potential range of the strength of HCN emission and its effect on the CO auto power spectrum, using simulations with an empirical model of the CO/HCN--halo connection. We find that effects on the observed CO power spectrum vary with modeling approaches but are very small for our fiducial model, with the undesirable boost in overall CO detection significance due to HCN expected to be less than 1%.
J S Wark - One of the best experts on this subject based on the ideXlab platform.
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Line Intensity enhancements in stellar coronal x ray spectra due to opacity effects
Astronomy and Astrophysics, 2008Co-Authors: S J Rose, M Matranga, Mihalis Mathioudakis, F P Keenan, J S WarkAbstract:Context. The I(15.01 A)/I(16.78 A) emission Line Intensity ratio in Fe xvii has been reported to deviate from its theoretical value in solar and stellar X-ray spectra. This is attributed to opacity in the 15.01 A Line, leading to a reduction in its Intensity, and was interpreted in terms of a geometry in which the emitters and absorbers are spatially distinct. Aims. We study the I(15.01 A)/I(16.78 A) Intensity ratio for the active cool dwarf EV Lac, in both flare and quiescent spectra. Methods. The observations were obtained with the Reflection Grating Spectrometer on the XMM-Newton satellite. The emission measure distribution versus temperature reconstruction technique is used for our analysis. Results. We find that the 15.01 A Line exhibits a significant enhancement in Intensity over the optically thin value. To our knowledge, this is the first time that such an enhancement has been detected on such a sound statistical basis. We interpret this enhancement in terms of a geometry in which the emitters and absorbers are not spatially distinct, and where the geometry is such that resonant pumping of the upper level has a greater effect on the observed Line Intensity than resonant absorption in the Line-of-sight.
