RandomFront 2.3: a physical parameterisation of fire spotting for operational fire spread models-implementation in WRF-SFIRE and response analysis with LSFire+

Fire spotting is often responsible for dangerous flare-ups in wildfires and causes secondary ignitions isolated from the primary fire zone, which lead to perilous situations. The main aim of the present research is to provide a versatile probabilistic model for fire spotting that is suitable for implementation as a post-processing scheme at each time step in any of the existing operational large-scale wildfire propagation models, without calling for any major changes in the original framework. In particular, a complete physical parameterisation of fire spotting is presented and the corresponding updated model RandomFront 2.3 is implemented in a coupled fire?atmosphere model: WRF-SFIRE. A test case is simulated and discussed. Moreover, the results from different simulations with a simple model based on the level set method, namely LSFire+, highlight the response of the parameterisation to varying fire intensities, wind conditions and different firebrand radii. The contribution of the firebrands to increasing the fire perimeter varies according to different concurrent conditions, and the simulations show results in agreement with the physical processes. Among the many rigorous approaches available in the literature to model firebrand transport and distribution, the approach presented here proves to be simple yet versatile for application to operational large-scale fire spread models.This research was supported by the Basque Government through the BERC 2014–2017 and BERC 2018–2021 programs. It was also funded by the Spanish Ministry of Economy and Competitiveness MINECO via the BCAM Severo Ochoa SEV-2013-0323 and SEV-2017-0718 accreditations, the MTM2013-40824-P “ASGAL” and MTM2016-76016-R “MIP” projects, and the PhD grant “La Caixa 2014”

Spectral Representation for the Effective Macroscopic Response of a Polycrystal: Application to Third-Order Nonlinear Susceptibility

Erratum: In our paper, we show that the spectral representation for isotropic two-component composites also applies to uniaxial polycrystals. We have learned that this result was, in fact, first conjectured by G.W. Milton. While our derivation is more detailed, our result for the spectral function is the same as Milton's. We very much regret not having been aware of this work at the time of writing our paper. Original abstract: We extend the spectral theory used for the calculation of the effective linear response functions of composites to the case of a polycrystalline material with uniaxially anisotropic microscopic symmetry. As an application, we combine these results with a nonlinear decoupling approximation as modified by Ma et al., to calculate the third-order nonlinear optical susceptibility of a uniaxial polycrystal, assuming that the effective dielectric function of the polycrystal can be calculated within the effective-medium approximation.Comment: v2 includes erratum and the original preprin

Characterization of high-temperature PbTe p-n junctions prepared by thermal diffusion and by ion-implantation

We describe here the characteristics of two types of high-quality PbTe p-n-junctions, prepared in this work: (1) by thermal diffusion of In4Te3 gas (TDJ), and (2) by ion implantation (implanted junction, IJ) of In (In-IJ) and Zn (Zn-IJ). The results, as presented here, demonstrate the high quality of these PbTe diodes. Capacitance-voltage and current-voltage characteristics have been measured. The measurements were carried out over a temperature range from ~ 10 K to ~ 180 K. The latter was the highest temperature, where the diode still demonstrated rectifying properties. This maximum operating temperature is higher than any of the earlier reported results. The saturation current density, J0, in both diode types, was ~ 10^-5 A/cm2 at 80 K, while at 180 K J0 ~ 10^-1 A/cm2 in TDJ and ~ 1 A/cm2 in both ion-implanted junctions. At 80 K the reverse current started to increase markedly at a bias of ~ 400 mV for TDJ, and at ~550 mV for IJ. The ideality factor n was about 1.5-2 for both diode types at 80 K. The analysis of the C-V plots shows that the junctions in both diode types are linearly graded. The analysis of the C-V plots allows also determining the height of the junction barrier, the concentrations and the concentration gradient of the impurities, and the temperature dependence of the static dielectric constant. The zero-bias-resistance x area products (R0Ae) at 80 K are: 850 OHMcm2 for TDJ, 250 OHMcm2 for In-IJ, and ~ 80 OHMcm2 for Zn-IJ, while at 180 K R0Ae ~ 0.38 OHMcm2 for TDJ, and ~ 0.1 OHMcm2 for IJ. The estimated detectivity is: D* ~ 10^10 cmHz^(1/2)/W up to T=140 K, determined mainly by background radiation, while at T=180 K, D* decreases to 108-107 cmHz^(1/2)/W, and is determined by the Johnson noise

Geometric structures of the N,N-dimethylamides and N-methylanilides of arylsulfonic acids

1. Dipole moments and components of the poiarizability tensor have been calculated for the S-N bond in the sulfamides. 2. The aryl radicals in the N,N-dimethylsulfamides project out of the C-S-N plane by an angle of 66 ±10°. 3. In the arylsulfanilides, the angle of rotation around the S-N bond is 270 t{combining short stroke overlay} 30°. 4. The fact that the angle of aryl rotation at the N atom is not dependent on the nature of the substituent is an indication that there is only negligible conjugation between the aromatic ring and the unshared electron pair of the nitrogen. © 1980 Plenum Publishing Corporation

Three-dimensional structure of aryl methyl sulfoxides and α-halomethyl aryl sulfoxides

1. Aryl methyl sulfoxides have a conformation close to an overlapping location of the S-O bond and the plane of the aromatic ring. 2. For the α-halomethyl aryl sulfoxides, we have established an equilibrium of three conformers with predominance of gauche forms. © 1982 Plenum Publishing Corporation

Thermal Wave Induced Edge Electrical Field of Pyroelectric: Spatial Pattern Mapping and Effect of Ambient Conditions

We have recently analyzed theoretically the main characteristics of the edge depolarizing electric field (EDEF), in the vicinity of a non-polar face of a pyroelectric. In this work we measured and characterized the EDEF, excited by a harmonical thermal wave. We present here experimental results obtained on a pyroelectric crystal LiTaO3, confirming our theoretical predictions. We present the theoretical analysis and description of the thermal wave and the induced harmonically varying EDEF. The calculations assume an equivalent circuit of a pyroelectric capacitive current source. The measured magnitude of the EDEF and its spatial variation agree well with the theoretical model. The effect of the air pressure at the pyroelectric/air interface, on the EDEF, was determined in the interval 10^3 - 10^-6 torr. We found that EDEF increases significantly with decreasing air pressure, presumably due to diminishing of adsorption screening at the polar faces. Teflon plates, covering the polar faces, prevent accumulation of screening charged particles, resulting in a drastic increase of EDEF

Conformations of the methyl and aryl esters of the arylsulfonic acids

1. The substituted methylarylsulfonates and arylarylsulfonates exist as mixtures of trans and gauche conformers, the latter predominating at equilibrium (∼70%). 2. The angle of aryl group rotation relative to the Csp3-S-O plane is 43° in the methylphenylsulfonates and the methyl-p-tolylsulfonates and 75° in the methyl-p-bromophenylsulfonates. 3. As a result of electron-acceptor effects from the SO2 group, the S-O-C plane of the arylsulfonic acids esters are almost perpendicular to the aromatic ring. © 1980 Plenum Publishing Corporation

Study of rotational isomerism in arylmethanesulfonates

In solution, the arylmethanesulfonates exist as two conformers with the methyl and aryl radicals in gauche and trans configurations. © 1979 Plenum Publishing Corporation

Investigation of the steric structure of certain compounds of the bicyclo-[4,2,0]octan-7-one series

1. The steric structure of adducts of dichloroketene and cyclohexene, dichloroketene and methyl-cyclohexene, dimethylketene and dihydropyran was investigated by the methods of dipole moments and molar Kerr constants. 2. For all the adducts, the preferential conformation of the bicyclo[4,2,0]octan-7-one system is the anti-boat conformation. 3. The adduct of dimethylketene and dihydropyran has the structure of 8,8-dimethyl-2-oxobicyclo-[4,2,0] octan-7-one. The formation of such a structure is apparently determined by the electron donor influence of the oxygen atom in dihydropyran on the process of cycloaddition. © 1974 Consultants Bureau

Three-dimensional structures of some perhydro-1,4-thiazine derivatives

A number of perhydro-1,4-thiazine S-oxides and S,S-dioxides were synthesized. Their IR and PMR spectra were studied, and their dipole moments were determined. The latter were compared with the calculated values for the chair conformation with various orientations of the substituents. Conclusions were drawn regarding the configuration and conformation of the investigated compounds. © 1974 Consultants Bureau