SwePub - search: WFRF:(Cooray V.)

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1.	Pezzotta, A., et al. (author) Euclid preparation XLI. Galaxy power spectrum modelling in real space 2024 In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 687 Journal article (peer-reviewed)abstract We investigate the accuracy of the perturbative galaxy bias expansion in view of the forthcoming analysis of the Euclid spectroscopic galaxy samples. We compare the performance of a Eulerian galaxy bias expansion using state-of-the-art prescriptions from the effective field theory of large-scale structure (EFTofLSS) with a hybrid approach based on Lagrangian perturbation theory and high-resolution simulations. These models are benchmarked against comoving snapshots of the flagship I N-body simulation at z = (0.9, 1.2, 1.5, 1.8), which have been populated with H alpha galaxies leading to catalogues of millions of objects within a volume of about 58 h(-3) Gpc(3). Our analysis suggests that both models can be used to provide a robust inference of the parameters (h, omega c) in the redshift range under consideration, with comparable constraining power. We additionally determine the range of validity of the EFTofLSS model in terms of scale cuts and model degrees of freedom. From these tests, it emerges that the standard third-order Eulerian bias expansion - which includes local and non-local bias parameters, a matter counter term, and a correction to the shot-noise contribution - can accurately describe the full shape of the real-space galaxy power spectrum up to the maximum wavenumber of k(max) = 0.45 h Mpc(-1), and with a measurement precision of well below the percentage level. Fixing either of the tidal bias parameters to physically motivated relations still leads to unbiased cosmological constraints, and helps in reducing the severity of projection effects due to the large dimensionality of the model. We finally show how we repeated our analysis assuming a volume that matches the expected footprint of Euclid, but without considering observational effects, such as purity and completeness, showing that we can get constraints on the combination (h, omega c) that are consistent with the fiducial values to better than the 68% confidence interval over this range of scales and redshifts.
2.	Cooray, V, et al. (author) A channel base current model to represent both negative and positive first return strokes with connecting leaders 2002 In: Proceedings of the 26th International Conference on Lightning Protection, Cracow, Poland. ; , s. 36-41 Conference paper (other academic/artistic)
3.	Cooray, V., et al. (author) A Novel Modification of the ’Transmission Line Model’ of Lightning Return Strokes 2002 In: 26th International Conference on Lightning Protection, ICLP2002, Cracow, Poland, September 2-6, Vol. 1, p50-55. ; , s. 50-55 Conference paper (peer-reviewed)
4.	Cooray, V, et al. (author) Lightning-induced overvoltages in power lines: Validity of various approximations made in overvoltage calculations 1998 In: IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9375. ; 40:4, s. 355-363 Journal article (other academic/artistic)abstract In this paper, the validity of different approximations used in the calculation of induced overvoltages in power lines are investigated, These approximations are as follows: 1) neglect the distortions introduced by the finitely conducting ground on the el
5.	Cooray, V, et al. (author) The Deep Physics Hidden within the Field Expressions of the Radiation Fields of Lightning Return Strokes (vol 7, pg 21, 2016) 2016 In: ATMOSPHERE. - : MDPI AG. - 2073-4433. ; 7:3 Journal article (other academic/artistic)abstract The authors would like to correct the published article [1] as follows.[...]
6.	Galvan, A, et al. (author) Effects of lightning electromagnetic field pulses (LEMP) in low voltage power installations 1998 In: 24th International Conference on Lightning Protection (ICLP), Birmingham, UK, Sept 14-18. ; , s. 729-734 Conference paper (peer-reviewed)
7.	Galvan, A, et al. (author) Interaction of electromagnetic fields from cloud and ground lightning flashes with an artificial low-voltage power installation 1999 In: IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9375. ; 41:3, s. 250-257 Journal article (other academic/artistic)abstract In most of the studies dealing with electromagnetic field interaction between nearby lightning flashes and electrical installations, the cloud flashes are assumed to play an insignificant role. However, our studies show that cloud flashes call generate in
8.	Gao, L, et al. (author) Measurement of the positive streamer charge 2000 In: Journal of Physics D: Applied Physics. ; 33, s. 1861-1865 Journal article (peer-reviewed)
9.	Gao, L, et al. (author) Simulation of streamer discharges as finitely conducting channels 1999 In: IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1070-9878. ; 6:1, s. 35-42 Journal article (other academic/artistic)abstract This paper presents a two-dimensional simulation of positive streamers in air at atmospheric pressure in a quasi-uniform electric field. A streamer is assumed to consist of a hemispherical tip and a finitely conducting cylindrical channel with a constant
10.	Gao, L, et al. (author) Study of cathode-directed positive streamers in air by streamer current and luminosity measurements 1997 In: IEEE Conference on Electrical Insulation and Dielectric Phenomena, Minneapolis, USA, Oct 19-22. ; , s. 587-590 Conference paper (peer-reviewed)
11.	Peer, J, et al. (author) Transcranial stimulability of phosphenes by long lightning electromagnetic pulses (vol 374, pg 2932, 2010) 2010 In: PHYSICS LETTERS A. - : Elsevier BV. - 0375-9601. ; 374:47, s. 4797-4799 Journal article (other academic/artistic)
12.	Roman, F, et al. (author) A comparative study of corona discharges in a coaxial cylinder using electric field impulses generated by electrically floating electrodes 1999 In: JOURNAL OF ELECTROSTATICS. - : ELSEVIER SCIENCE BV. - 0304-3886. ; 47:3, s. 99-120 Journal article (other academic/artistic)abstract Corona discharges in a cylindrical coaxial arrangement were studied when well-defined voltage impulses of both polarities were applied to the axial conductor either directly or through a series gap. These comparative experiments were called the reference
13.	Roman, F, et al. (author) Comparison of the breakdown of rod-plane gaps with floating electrode 1998 In: IEEE TRANSACTIONS ON DIELECTRICS AND ELECTRICAL INSULATION. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1070-9878. ; 5:4, s. 622-624 Journal article (other academic/artistic)abstract The possible influence of a metal body in a lightning protection system was determined by comparing the electrical breakdown probability of two symmetrical sphere-rod gaps, one conventional and the other with a floating electrode, i.e. a rod with a series
14.	Roman, F, et al. (author) Corona from floating electrodes 1996 In: JOURNAL OF ELECTROSTATICS. - : ELSEVIER SCIENCE BV. - 0304-3886. ; 37:1-2, s. 67-78 Journal article (other academic/artistic)abstract It is not unusual to have insulated conducting objects located close to the conductors of a Lightning Protection System. However, the separation of these objects from the Lightning Protection System could vary from a few millimetres to some centimetres. W
15.	Roman, F, et al. (author) Corona from floating electrodes (vol 37, pg 67, 1996) 1996 In: JOURNAL OF ELECTROSTATICS. - : ELSEVIER SCIENCE BV. ; 38:4 Other publication (other academic/artistic)
16.	Roman, F, et al. (author) Increase in the visual corona from floating electrodes 1999 In: JOURNAL OF ELECTROSTATICS. - : ELSEVIER SCIENCE BV. - 0304-3886. ; 45:4, s. 243-254 Journal article (other academic/artistic)abstract The corona and streamer discharges on a floating metallic rod located close to a high-voltage electrode were investigated under the application of both positive and negative 300/3000 mu s switching impulses. The distance between the floating rod and the h
17.	Silfverskiold, S, et al. (author) Induced voltages in a low-voltage power installation network due to lightning electromagnetic fields: An experimental study 1999 In: IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9375. ; 41:3, s. 265-271 Journal article (peer-reviewed)abstract This paper presents the experimental results on the induced common-mode (CM) voltages in a residential low-voltage power installation (LVPI) network exposed to electromagnetic fields from lightning, The objective of this investigation was to find out the
18.	Silfverskiöld, S, et al. (author) Induced voltages in a low voltage power installation network due to lightning electromagnetic fields 1996 In: 23rd International Conference on Lightning Protection (ICLP), Florence, Italy, Sept 23-27. ; , s. 334-339 Conference paper (peer-reviewed)
19.	Theethayi, N, et al. (author) Modeling Direct Lightning Attachment to Electrified Railway System in Sweden 2003 In: IEEE Bologna Power Tech, Italy, June 23-26. ; :paper no. 72 Conference paper (other academic/artistic)
20.	Akyuz, M, et al. (author) 3D simulation of streamer branching in air 2003 In: Journal of Electrostatics. ; 59, s. 115-141 Journal article (peer-reviewed)
21.	Akyuz, M, et al. (author) 3D Simulations of Streamer Branching in Air 2002 Reports (other academic/artistic)
22.	Akyuz, M, et al. (author) Characteristics of laser-triggered electric discharges in air 2005 In: IEEE Transactions on Dielectrics and Electrical Insulation. - 1070-9878. ; 12:5, s. 1060-1070 Journal article (peer-reviewed)abstract An experiment of laser-triggered electric discharges has been conducted in a uniform background electric field. By focusing the beam of a pulsed Nd-YAG laser (wavelength 532 nm, pulse duration 5 ns) in a narrow (15 mm) plane-parallel air gap exposed to a dc voltage, streamer discharges and disruptive discharges were triggered.. The laser energy and the background electric field strength were varied in the ranges 0-180 mJ and 0.8-1.4 MV/m, respectively, and the laser plasma was induced either close to the anode, close to the cathode or mid-gap. From images of the electrode gap and from current measurements, the occurrence of and time to the streamer discharge and the disruptive discharge were determined. No distinct level was found of either the laser energy or the plasma energy for the transition from one discharge case to another, even if the general trend was that the energy required for a certain discharge case was reduced when increasing the background electric field. These and other observations make the method of laser triggering a less suitable method for studies of streamer initiation and streamer propagation, but revealed several interesting features of laser-triggered electric discharges.
23.	Akyuz, M, et al. (author) Positive Streamer Discharges along Insulating Surfaces 2001 In: IEEE Transactions on Dielectrics and Electrical Insulation. ; 8:6, s. 902-910 Journal article (peer-reviewed)
24.	Akyuz, M, et al. (author) Streamer current in a three-electrode system 2001 In: IEEE Transactions on Dielectrics and Electrical Insulation. ; 8:4, s. 665-672 Journal article (peer-reviewed)
25.	Akyuz, M, et al. (author) The Franklin lightning conductor: Conditions necessary for the initiation of a connecting leader 2001 In: Journal of Electrostatics. ; 51-52, s. 319-325 Journal article (peer-reviewed)
26.	Bakx, Tom, 1990, et al. (author) A dusty protocluster surrounding the binary galaxy HerBS-70 at z = 2.3 2024 In: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 530:4, s. 4578-4596 Journal article (peer-reviewed)abstract We report on deep SCUBA-2 observations at 850 μm and NOrthern Extended Millimetre Array (NOEMA) spectroscopic measurements at 2 mm of the environment surrounding the luminous, massive (M∗ ≈ 2 × 1011 M☉) Herschel-selected source HerBS-70. This source was revealed by previous NOEMA observations to be a binary system of dusty star-forming galaxies at z = 2.3, with the east component (HerBS-70E) hosting an active galactic nucleus. The SCUBA-2 observations detected, in addition to the binary system, 21 sources at >3.5σ over an area of ∼25 square comoving Mpc with a sensitivity of 1σ850 = 0.75 mJy. The surface density of continuum sources around HerBS-70 is three times higher than for field galaxies. The NOEMA spectroscopic measurements confirm the protocluster membership of three of the nine brightest sources through their CO(4–3) line emission, yielding a volume density 36 times higher than for field galaxies. All five confirmed sub-mm galaxies in the HerBS-70 system have relatively short gas depletion times (80−500 Myr), indicating the onset of quenching for this protocluster core due to the depletion of gas. The dark matter halo mass of the HerBS-70 system is estimated around 5 × 1013 M☉, with a projected current-day mass of 1015 M☉, similar to the local Virgo and Coma clusters. These observations support the claim that DSFGs, in particular the ones with observed multiplicity, can trace cosmic overdensities.
27.	Bendo, G. J., et al. (author) The bright extragalactic ALMA redshift survey (BEARS) – II. Millimetre photometry of gravitational lens candidates 2023 In: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 522:2, s. 2995-3017 Journal article (peer-reviewed)abstract We present 101- and 151-GHz ALMA continuum images for 85 fields selected from Herschel observations that have 500-μm flux densities >80 mJy and 250–500-μm colours consistent with z > 2, most of which are expected to be gravitationally lensed or hyperluminous infrared galaxies. Approximately half of the Herschel 500-μm sources were resolved into multiple ALMA sources, but 11 of the 15 brightest 500-μm Herschel sources correspond to individual ALMA sources. For the 37 fields containing either a single source with a spectroscopic redshift or two sources with the same spectroscopic redshift, we examined the colour temperatures and dust emissivity indices. The colour temperatures only vary weakly with redshift and are statistically consistent with no redshift-dependent temperature variations, which generally corresponds to results from other samples selected in far-infrared, submillimetre, or millimetre bands but not to results from samples selected in optical or near-infrared bands. The dust emissivity indices, with very few exceptions, are largely consistent with a value of 2. We also compared spectroscopic redshifts to photometric redshifts based on spectral energy distribution templates designed for infrared-bright high-redshift galaxies. While the templates systematically underestimate the redshifts by ∼15 per cent, the inclusion of ALMA data decreases the scatter in the predicted redshifts by a factor of ∼2, illustrating the potential usefulness of these millimetre data for estimating photometric redshifts.
28.	Berta, S., et al. (author) z -GAL: A NOEMA spectroscopic redshift survey of bright Herschel galaxies: III. Physical properties 2023 In: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 678 Journal article (peer-reviewed)abstract The z-GAL survey observed 137 bright Herschel-selected targets with the IRAM Northern Extended Millimeter Array, with the aim to measure their redshift and study their properties. Several of them have been resolved into multiple sources. Consequently, robust spectroscopic redshifts have been measured for 165 individual galaxies in the range 0.8., <., z., <., 6.5. In this paper we analyse the millimetre spectra of the z-GAL sources, using both their continuum and line emission to derive their physical properties. At least two spectral lines are detected for each source, including transitions of 12CO, [CI], and H2O. The observed 12CO line ratios and spectral line energy distributions of individual sources resemble those of local starbursts. In seven sources the para-H2O (211-202) transition is detected and follows the IR versus H2O luminosity relation of sub-millimetre galaxies. The molecular gas mass of the z-GAL sources is derived from their 12CO, [CI], and sub-millimetre dust continuum emission. The three tracers lead to consistent results, with the dust continuum showing the largest scatter when compared to 12CO. The gas-to-dust mass ratio of these sources was computed by combining the information derived from 12CO and the dust continuum and has a median value of 107, similar to star-forming galaxies of near-solar metallicity. The same combined analysis leads to depletion timescales in the range between 0.1 and 1.0 Gyr, which place the z-GAL sources between the main sequence' of star formation and the locus of starbursts. Finally, we derived a first estimate of stellar masses "modulo possible gravitational magnification "by inverting known gas scaling relations: the z-GAL sample is confirmed to be mostly composed by starbursts, whereas ∼25% of its members lie on the main sequence of star-forming galaxies (within ±0.5 dex).
29.	Cooray, Vernon, et al. (author) A current generation type return stroke model that predicts the return stroke velocity 2006 Conference paper (peer-reviewed)
30.	Cooray, V (author) A model for negative first return strokes in lightning flashes 1997 In: PHYSICA SCRIPTA. - : ROYAL SWEDISH ACAD SCIENCES. - 0281-1847. ; 55:1, s. 119-128 Journal article (other academic/artistic)abstract A model is introduced to describe negative first return strokes in lightning ground hashes. The basic assumptions made are similar to those used previously to describe the subsequent return strokes. The model predictions are in general agreement with expe
31.	Cooray, V (author) A model for positive return strokes 1995 In: ELECTROSTATICS 1995. - : IOP PUBLISHING LTD. - 0951-3248. ; 143, s. 363-371 Journal article (other academic/artistic)abstract A model to describe positive return strokes is presented. The basic concepts used in the model are essentially similar to those used previously to describe negative first return strokes. However, laboratory experiments indicate that the mechanism of neutr
32.	Cooray, V, et al. (author) A Negative First Return Stroke Model For Engineering Applications 2000 In: 25th International Conference on Lightning Protection, Rhodos, Greece. Conference paper (peer-reviewed)
33.	Cooray, V (author) Charge and Voltage Characteristics of Corona Discharges in a Coaxial Geometry 2000 In: IEEE Transactions on Dielectrics and Electrical Insulation. ; 7:6 Journal article (peer-reviewed)
34.	Cooray, V (author) Electric field at the discharge tip couples the speed and currents of dart leaders, return strokes and M-components 1997 In: JOURNAL OF ELECTROSTATICS. - : ELSEVIER SCIENCE BV. - 0304-3886. ; 40-1, s. 85-90 Journal article (other academic/artistic)abstract Lightning leaders, return strokes and M-components can be treated as self-propagating discharges which carry a high electric field at their tip. The magnitude of this field depends on the current parameters and the speed of the discharge. On the other han
35.	Cooray, V (author) Energy dissipation in lightning flashes 1997 In: JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. - : AMER GEOPHYSICAL UNION. ; 102:D17, s. 21401-21410 Journal article (other academic/artistic)abstract In this paper the amounts of energy dissipation in different stages of ground flashes are estimated by electrostatic energy considerations. In the analysis the cloud is modeled using the typical charge configuration given by Malan [1963]. The leader stage
36.	Cooray, V, et al. (author) Estimation of peak return stroke currents, current time derivatives and return stroke velocities from measured fields 1998 In: JOURNAL OF ELECTROSTATICS. - : ELSEVIER SCIENCE BV. - 0304-3886. ; 43:3, s. 163-172 Journal article (other academic/artistic)abstract Eighteen subsequent return stroke fields from triggered lightning flashes, observed at 5.16 km were used to test the ability of a return stroke model to predict the return stroke peak currents, peak current time derivatives and return stroke velocities fr
37.	Cooray, Vernon, et al. (author) On the Constraints Imposed by the Close Electric Field Signature on the Equivalent Corona Current in Lightning Return Stroke Models 2004 In: International Conference on Lightning Protection, Avignon, France. Conference paper (other academic/artistic)
38.	Cooray, Vernon, et al. (author) On the Electric field at the tip of dart leaders in lightning flashes 2006 In: Proceedings of the 28th Internat Conference on Lightning Protection, ICLP, Kanazawa, Japan. ; , s. 339-344 Conference paper (peer-reviewed)
39.	Cooray, Vernon, et al. (author) On the mechanism of X-ray production by dart leaders of lightning flashes 2010 In: Journal of Atmospheric and Solar-Terrestrial Physics. - 1364-6826 .- 1879-1824. ; 72, s. 848-855 Journal article (peer-reviewed)
40.	Cooray, Vernon, et al. (author) On the NOx production in lightning flashes 2007 Conference paper (other academic/artistic)
41.	Cooray, V., et al. (author) Physical Model of Surge-Current Characteristics of buried vertical Rods in the Presence of Soil Ionisation 2002 In: 26th International Conference on Lightning Protection, ICLP-2002, Cracow, Poland, September 2-6, Vol. 1, p357-362. ; , s. 357-362 Conference paper (peer-reviewed)
42.	Cooray, V (author) Predicting the spatial and temporal variation of the electromagnetic fields, currents, and speeds of subsequent return strokes 1998 In: IEEE TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9375. ; 40:4, s. 427-435 Journal article (other academic/artistic)abstract A mathematical model with a physical basis is introduced to describe the subsequent return strokes in lightning flashes. The input parameters of the model are the channel-base current and the charge distribution along the leader-term-stroke channel. Once
43.	Cooray, V, et al. (author) Propagation of lightning generated transient electromagnetic fields over finitely conducting ground 2000 In: Journal of Atmospheric and Solar-Terrestrial Physics. ; 62, s. 583-600 Journal article (peer-reviewed)
44.	Cooray, V (author) Some considerations on the Cooray-Rubinstein Formulation Used in Deriving the Horizontal Electric Field of Lightning Return Strokes Over Finitely Conducting Ground 2002 In: IEEE Transactions on Electromagnetic Compatibility. ; 44:4, s. 560-566 Journal article (peer-reviewed)
45.	Cooray, V, et al. (author) The Fine Structure of Positive Return Stroke Radiation Fields 2004 In: IEEE Transactions on EMC. ; 46, s. 87-95 Journal article (peer-reviewed)
46.	Cooray, V (author) The modelling of positive return strokes in lightning flashes 2000 In: Journal of Atmospheric and Solar-Terrestrial Physics. ; 62, s. 169-187 Journal article (peer-reviewed)
47.	Cooray, V, et al. (author) The Stepped Leader As A Source of Interference In Electrical Installations 2000 In: 25th International Conference on Lightning Protection, Rhodos, Greece. Conference paper (peer-reviewed)
48.	Cooray, V (author) Underground electric fields generated by the return strokes of lightning flashes 2001 In: IEEE Transactions on Electromagnetic Compatibility. ; 43, s. 75-84 Journal article (peer-reviewed)
49.	Cooray, V (author) Variation of return stroke velocity over the first few hundred meters and its relationship to the slow front in return stroke radiation fields 1995 In: ELECTROSTATICS 1995. - : IOP PUBLISHING LTD. - 0951-3248. ; 143, s. 235-240 Journal article (other academic/artistic)abstract The return stroke velocity along the first hundred meters of the return stroke channel was calculated by using a novel concept introduced by Cooray [1]. The results show that the subsequent return stroke velocity is initially low but rapidly increases ove
50.	Cooray, V, et al. (author) What directs a lightning flash towards ground? 2000 In: Sri Lankan Journal of Physics. ; 1, s. 1-10 Journal article (peer-reviewed)

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