Dimensionless Intensity Research Articles

Vibrational Raman optical activity of bicyclic terpenes: comparison between experimental and calculated vibrational Raman, Raman optical activity, and dimensionless circular intensity difference spectra and their similarity analysis

Experimental vibrational Raman, vibrational Raman optical activity (VROA), and dimensionless circular intensity difference (CID) spectra are analyzed with quantum chemical (QC) predictions of the corresponding spectra using the B3LYP functional and the aug-cc-pVDZ basis set, for five bicyclic terpenes as test cases. The experimentally measured vibrational Raman and VROA spectra have arbitrary y-axis intensities, because of their dependence on instrumental parameters. As a result, the absolute magnitudes of intensities in experimental and calculated vibrational Raman or vibrational ROA spectra are not normally analyzed. However, the experimental dimensionless CID spectrum is independent of the instrumental parameters and can be evaluated quantitatively with corresponding QC predicted CID spectrum. The similarity overlaps between experimental and quantum chemical predictions of vibrational Raman, VROA, and dimensionless CID spectra are evaluated. The quantum chemical predictions of dimensionless CID spectral magnitudes at B3LYP/aug-ccpVDZ level match well with the corresponding experimental magnitudes. The individual anisotropic contributions to VROA and CID spectra are also presented. The anisotropic contribution involving electric dipole-electric quadrupole polarizability derivative tensor is relatively smaller than that involving electric dipole-magnetic dipole polarizability derivative tensor. A new format, which contains all of the information needed for the spectral analysis, has been advanced for presenting the vibrational Raman, VROA, and CID spectra and their similarity analysis with corresponding QC-predicted spectra. Copyright © 2016 John Wiley & Sons, Ltd.

Sono-chemiluminescence (SCL) in a high-pressure double stage homogenization processes

An applied back-pressure to a high pressure homogenization system influences the development of hydrodynamic cavitation and the collapse of cavitation bubbles. This paper focuses on the effect of back-pressure on hydrodynamic cavitation and how the intensity of collapsing cavitation bubbles can be identified. Based on sono-chemiluminescence (SCL), an optical measuring method was developed to detect cavitation induced formation of •OH radicals, which indicates the intensity of collapsing cavities. The results are discussed with the introduced dimensionless SCL intensity number I¯SCL. The I¯SCL number increases with increasing inlet pressure as well as with increasing back-pressure and confirms therewith theoretical based assumptions by other studies. A maximum I¯SCL at a back-pressure of approximately 30% was found and reduced to an intensified collapse of cavities in or after the first high pressure disruption unit. The maximum in SCL intensity is in line with the minimum droplet size of corresponding emulsification experiments.

Degeneration of internal Kelvin waves in a continuous two-layer stratification

We explore the evolution of the gravest internal Kelvin wave in a two-layer rotating cylindrical basin, using direct numerical simulations (DNS) with a hyper-viscosity/diffusion approach to illustrate different dynamic and energetic regimes. The initial condition is derived from Csanady’s (J. Geophys. Res., vol. 72, 1967, pp. 4151–4162) conceptual model, which is adapted by allowing molecular diffusion to smooth the discontinuous idealized solution over a transition scale, ${\it\delta}_{i}$, taken to be small compared to both layer thicknesses $h_{\ell },\ell =1,2$. The different regimes are obtained by varying the initial wave amplitude, ${\it\eta}_{0}$, for the same stratification and rotation. Increasing ${\it\eta}_{0}$ increases both the tendency for wave steepening and the shear in the vicinity of the density interface. We present results across several regimes: from the damped, linear–laminar regime (DLR), for which ${\it\eta}_{0}\sim {\it\delta}_{i}$ and the Kelvin wave retains its linear character, to the nonlinear–turbulent transition regime (TR), for which the amplitude ${\it\eta}_{0}$ approaches the thickness of the (thinner) upper layer $h_{1}$, and nonlinearity and dispersion become significant, leading to hydrodynamic instabilities at the interface. In the TR, localized turbulent patches are produced by Kelvin wave breaking, i.e. shear and convective instabilities that occur at the front and tail of energetic waves within an internal Rossby radius of deformation from the boundary. The mixing and dissipation associated with the patches are characterized in terms of dimensionless turbulence intensity parameters that quantify the locally elevated dissipation rates of kinetic energy and buoyancy variance.

The use of topology in fracture network characterization

In two-dimensions, a fracture network consist of a system of branches and nodes that can be used to define both geometrical features, such as length and orientation, and the relationship between elements of the network – topology. Branch lengths are preferred to trace lengths as they can be uniquely defined, have less censoring and are more clustered around a mean value. Many important properties of networks are more related to topology than geometry.The proportions of isolated (I), abutting (Y) and crossing (X) nodes provide a basis for describing the topology that can be easily applied, even with limited access to the network as a whole. Node counting also provides an unbiased estimate of frequency and can be used in conjunction with fracture intensity to estimate the characteristic length and dimensionless intensity of the fractures. The nodes can be used to classify branches into three types – those with two I-nodes, one I-node and no I-nodes (or two connected nodes). The average number of connections per branch provides a measure of connectivity that is almost completely independent of the topology. We briefly discuss the extension of topological concepts to 3-dimensions.

Seismic response of sliding equipment and contents in base‐isolated buildings subjected to broadband ground motions

SummaryBase isolation has been established as the seismic design approach of choice when it comes to protecting nonstructural contents. However, while this protection technology has been widely shown to reduce seismic demands on attached oscillatory equipment and contents (EC), its effectiveness in controlling the response of freestanding EC that are prone to sliding has not been investigated. This study examines the seismic behavior of sliding EC inside base‐isolated buildings subjected to broadband ground motions. The effect of isolation system properties on the response of sliding EC with various friction coefficients is examined. Two widely used isolation models are considered: viscously damped linear elastic and bilinear. The study finds isolation to be generally effective in reducing seismic demands on sliding EC, but it also exposes certain situations where isolation in fact increases demands on EC, most notably for low friction coefficients and high earthquake intensities. Damping at the isolation level is effective in controlling the EC sliding displacements, although damping over about 20% is found to be superfluous. The study identifies a physically motivated dimensionless intensity measure and engineering demand parameter for sliding equipment in base‐isolated buildings subjected to broadband ground motions. Finally, the paper presents easy‐to‐use design fragility curves and an example that illustrates how to use them. Copyright © 2014 John Wiley & Sons, Ltd.

Experimental investigation of the wave-induced flow around a surface-touching cylinder

The wave-induced flow around a circular cylinder near both a rigid wall and an erodible bed is experimentally investigated using Particle Tracking Velocimetry (PTV). The aim of this study is to gain quantitative information on the local mean flow, the vorticity dynamics and the evolution of the erodible bed. The flow is characterized in terms of the Keulegan–Carpenter (KC), Reynolds (Re) and Ursell (Ur) numbers. The effects of changing these parameters over the ranges 1<KC<31, 3×103<Re<2.6×104 and 1.5<Ur<152 are investigated. For KC<1.1 the flow does not separate. When KC increases, the flow becomes unstable and large-scale vortical structures develop. The dimensionless intensity (|Γ⁎|) depends non-monotonically on KC, with a local maximum at KC=17, and the dimensionless area of the same macrovortex (A⁎) follows a somewhat similar law. Although the dimensionless boundary layer thickness (δ⁎) exhibits some discontinuities between KC regimes, it decreases with KC at x/D=0.5, as x/D=1 weakly depends on KC and can be regarded as constant (δ⁎=0.7) and then, increases with KC when moving away from the cylinder. These findings are used to interpret the physics governing the flow around a cylinder touching a wall and are compared with available results from the literature (Sumer et al., 1991). The evolution of the scour mechanism occurring over an erodible sandy bed is also investigated. The validity of some empirical formulas in the literature is also tested on the basis of the available dataset. The empirical relationships of Cevik and Yuksel (1999) and Sumer and Fredsøe (1990) for the dimensionless scour depth (S/D) agree well with our results. The dimensionless scour width (Ws/D) is predicted well by Sumer and Fredsøe's (2002) empirical equation for KC<23, whereas Catano-Lopera and Garcia's (2007) formula is more accurate for higher values of KC.

Radiation field modeling and optimization of a compact and modular multi-plate photocatalytic reactor (MPPR) for air/water purification by Monte Carlo method

The radiation field in a multi-plate photocatalytic reactor (MPPR) for air or water purification was modeled and optimized using a Monte Carlo stochastic method. The MPPR consists of parallel photocatalytic plates irradiated by cylindrical UV lamps orthogonal to the plates. The photocatalyst titanium dioxide (TiO2) is supported on the plates as a thin film. The photoreactor design is compact and offers a large irradiated photocatalytic surface area, a high degree of photon utilization, low pressure drop and a modular design which can facilitate scale-up. These features are desirable for the decontamination of indoor air in ventilation ducts or for water detoxification. The Monte Carlo method was applied to determine three dimensionless reactor performance parameters: the photon absorption efficiency (ϕ), the uniformity of the distribution of the dimensionless radiation intensity (η) and the overall photonic efficiency (Φ). The emission of photons from the light sources was simulated by the extensive source with superficial emission (ESSE) model. Simulations were performed by varying the catalyst reflectivity albedo, the number and the diameter of lamps, and the dimensions and spacing of the photocatalytic plates. Optimal design for a basic reactor module with one lamp was accomplished for lamp-diameter-to-plate-height ratio (β) of 0.7, while the plate-spacing-to-plate-height ratio (α) was correlated by [αoptimum=0.191β2−0.5597β+0.3854]. A multilamp arrangement leads to a feasible increase in the size and number of the plates and the irradiated photocatalytic surface area. The optimum design was validated by measuring the apparent quantum yield of the oxidation of toluene (7ppmv) in a humidified air stream using immobilized TiO2 (Degussa P25). Experiments performed varying the geometrical parameter α correlated well with the model calculations, with maximum apparent quantum yield for α=0.137. The results are directly transferable to the treatment of water by photocatalysis.

Radiation damping in pulsed Gaussian beams

We consider the effects of radiation damping on the electron dynamics in a Gaussian beam model of a laser field. For high intensities, i.e. with dimensionless intensity a0 \gg 1, it is found that the dynamics divide into three regimes. For low energy electrons (low initial {\gamma}-factor, {\gamma}0) the radiation damping effects are negligible. At higher energies, but still at 2{\gamma}0 < a0, the damping alters the final displacement and the net energy change of the electron. For 2{\gamma}0 > a0 one is in a regime of radiation reaction induced electron capture. This capture is found to be stable with respect to the spatial properties of the electron beam and results in a significant energy loss of the electrons. In this regime the plane wave model of the laser field provides a good description of the dynamics, whereas for lower energies the Gaussian beam and plane wave models differ significantly. Finally the dynamics are considered for the case of an XFEL field. It is found that the significantly lower intensities of such fields inhibits the damping effects.

Surpassing one x-ray photon per electron in nonlinear Thomson scattering in 180° geometry

We have obtained the general analytical expressions of harmonic radiation for Thomson scattering (TS) of arbitrary polarized laser by virtue of generalized Bessel functions and derived the extremum conditions for backscattered harmonics. Especially, for the fundamental backscattered Thomson scattering x-ray yield, we have shown that at the same conditions, the circular polarization reaches maximum while the linear case minimum. This effect is significant when a2≥1. With the assumption that the x-ray photon yield of a realistic focused pulse of energy E, wavelength λ, and Rayleigh range zR is equivalent to a plane wave pulse containing Nl cycles via the relation Nlλ=pzR where the effective factor p is of order one, we applied the plane wave results to realistic laser pulses and deduced that the backscattered x-ray photon number Nf per electron achieves its peak value when the average dimensionless laser intensity a2=0.677 and is irrelevant to the value of p. Since Nf and its maximum Nfmax both scale with the square root of E/λ, it is realizable to attain Nf≥1 using joule-scale laser pulses while a great challenge for Nf&amp;gt;10.

A low-cost needle-based single-fiber reflectance spectroscopy method to probe scattering changes associated with mineralization in intervertebral discs in chondrodystrophoid canine species – A pilot study

AbstractIntervertebral disc herniation is a common disease in chondrodystrophic dogs, and a similar neurologic condition also occurs in humans. Percutaneous laser disc ablation (PLDA) is a minimally invasive procedure used increasingly for prevention of disc herniation. PLDA is performed on thoracolumbar discs to which the same laser energy is applied regardless of their mineral content. Knowledge of individual disc mineral composition would allow laser energy dosage adjustments and more accurate treatment of degenerative discs. Usually, PLDA is guided by radiography/fluoroscopy, which has a limited sensitivity of approximately 60% for identification of mineralized discs. An imaging or sensing technology that provides a more accurate pre-operativeA pilot study was performed on a total of 21 intervertebral discs from two cadaveric dogs (“Dog A” and “Dog B”). The discs were imaged by computed tomography (CT), radiography, and SFR spectroscopy, before histopathologic examination. SFR spectroscopy in the visible/near-infrared band was performed on the nucleus pulposus of the intervertebral disc through a 20-gauge spinal needle placed percutaneously for PLDA. A normalization method was applied to the raw remission spectra to extract a dimension-less and wavelength-dependent intensity profile in the 500–950 nm spectral range.In total, six discs were determined to be degenerative on histopathology, five discs of “Dog A” and one disc of “Dog B”. CT diagnosed all six degenerated discs, whereas radiography missed two of the five degenerated discs of “Dog A”. The wavelength-dependent mean scattering intensity profiles of the six degenerated discs were noticeably higher than the mean scattering intensity profiles of the 15 “normal” or insignificantly mineralized discs over the entire spectral range. The mean scattering intensities, averaged over each of the entire profiles, were 2.79±0.58 (mean±SD) for the six degenerated discs and 1.48±0.37 for the 15 “normal” or insignificantly mineralized discs. A two-sampleSFR spectroscopy measurements indicate that the increase of light scattering intensity across the entire 500–950 nm spectral range is associated with the mineralization in canine intervertebral discs. However, the scattering characteristics of the nucleus pulposus measured in this study may not necessarily represent the optical properties of the nucleus pulposus at the laser wavelength used for PLDA (2100 nm). More studies on cadaveric and eventually

Transverse superresolution technique involving rectified Laguerre–Gaussian LG^0_p beams

A promising technique has been proposed recently [Opt. Commun. 284, 1331 (2011), Opt. Commun. 284, 4107 (2011)] for breaking the diffraction limit of light. This technique consists of transforming a symmetrical Laguerre-Gaussian LG(p)⁰ beam into a near-Gaussian beam at the focal plane of a thin converging lens thanks to a binary diffractive optical element (DOE) having a transmittance alternatively equal to -1 or +1, transversely. The effect of the DOE is to convert the alternately out-of-phase rings of the LG(p)⁰ beam into a unified phase front. The benefits of the rectified beam at the lens focal plane are a short Rayleigh range, which is very useful for many laser applications, and a focal volume much smaller than that obtained with a Gaussian beam. In this paper, we demonstrate numerically that the central lobe's radius of the rectified beam at the lens focal plane depends exclusively on the dimensionless radial intensity vanishing factor of the incident beam. Consequently, this value can be easily predicted.

Axisymmetric Problem of Energetically Consistent Interacting Annular and Penny-Shaped Cracks in Piezoelectric Materials

The axisymmetric problem of a concentric set of energetically consistent annular and penny-shaped cracks in an infinite piezoelectric body subjected to uniform far-field electromechanical loading is addressed. With the aid of a robust innovated technique, the pertinent four-part mixed boundary value problem (MBVP) is reduced to a decoupled Fredholm integral equation of the second kind. The results of two limiting cases of a single penny-shaped crack and a single annular crack are recovered. The contour plots of dimensionless intensity factors (IFs) at each crack front provide the stress and electric displacement intensity factors (SIFs and EDIFs, respectively) for all combination of crack sizes. The impermeable, permeable, and semipermeable models are also examined as limiting cases.

Experimental and analytical studies on the response of 1/4-scale models of freestanding laboratory equipment subjected to strong earthquake shaking

This paper investigates the seismic response of freestanding equipment when subjected to strong earthquake motions (2% probability of being exceeded in 50 years). A two-step approach is followed because the displacement limitations of the shake table do not permit full-scale experiments. First, shake table tests are conducted on quarter-scale wooden block models of the equipment. The results are used to validate the commercially available dynamic simulation software Working Model 2D. Working Model is then used to compute the response of the full-scale freestanding equipment when subjected to strong, 2% in 50 years hazard motions. The response is dominated by sliding, with sliding displacements reaching up to 70 cm. A physically motivated dimensionless intensity measure and the associated engineering demand parameter are identified with the help of dimensional analysis, and the results of the numerical simulations are used to obtain a relationship between the two that leads to ready-to-use fragility curves.

Turbulence characteristics of a small subtropical estuary during and after some moderate rainfall

In natural estuaries, scalar diffusion and dispersion are driven by turbulence. In the present study, detailed turbulence measurements were conducted in a small subtropical estuary with semi-diurnal tides under neap tide conditions. Three acoustic Doppler velocimeters were installed mid-estuary at fixed locations close together. The units were sampled simultaneously and continuously at relatively high frequency for 50 h. The results illustrated the influence of tidal forcing in the small estuary, although low-frequency longitudinal velocity oscillations were observed and believed to be induced by external resonance. The boundary shear stress data implied that the turbulent shear in the lower flow region was one order of magnitude larger than the boundary shear itself. The observation differed from turbulence data in a laboratory channel, but a key feature of natural estuary flow was the significant three-dimensional effects associated with strong secondary currents including transverse shear events. The velocity covariances and triple correlations, as well as the backscatter intensity and covariances, were calculated for the entire field study. The covariances of the longitudinal velocity component showed some tidal trend, while the covariances of the transverse horizontal velocity component exhibited trends that reflected changes in secondary current patterns between ebb and flood tides. The triple correlation data tended to show some differences between ebb and flood tides. The acoustic backscatter intensity data were characterised by large fluctuations during the entire study, with dimensionless fluctuation intensity I b ′ / I b ¯ between 0.46 and 0.54. An unusual feature of the field study was some moderate rainfall prior to and during the first part of the sampling period. Visual observations showed some surface scars and marked channels, while some mini transient fronts were observed.

Overpressure and slope stability in prograding clinoforms: Implications for marine morphodynamics

[1] Rapid deposition of fine-grained sediments can lead to overpressure buildup along the fronts of prograding sedimentary bodies (clinoforms) ranging from deltas to continental margins. Overpressure reduces shear strength, which can lead to failure of submarine slopes, so that overpressure prediction is potentially of fundamental importance to marine morphodynamics. We generalize one-dimensional overpressure theory to migrating clinoforms where deposition is highly localized in space and time, and show that overpressure is characterized by a dimensionless loading intensity, the Gibson number (given by the product of sediment supply and slope, divided by sediment hydraulic diffusivity). Our results show that compared to terrestrial slopes, slope stability in overpressured clinoforms is especially sensitive to foreset steepness, which directly affects loading intensity. The utility of our theory is demonstrated by application to modern and ancient clinoforms with documented slope failures. This analysis suggests that (1) most muddy clinoforms will have significant overpressure, (2) many delta fronts and continental margins prograde at a limiting slope threshold for deep-seated landsliding, and (3) shallow overpressure and near-surface liquefaction may contribute to mobilization of fluid muds which actively prograde subaqueous deltas. We derive quantitative relationships between sediment supply and slope for clinoforms prograding at limiting equilibrium. Importantly, our results suggest that slope is an inverse function of sediment supply in these systems, implying that commonly used diffusive morphodynamics approaches may be inappropriate.

Numerical Simulation of a Vertical Solar Collector Integrated in a Building Frame: Radiation and Turbulent Natural Convection Coupling

The presented work represents one part of the accurate studies led in a French Integrated Research Project supported by the CNRS. The context of this study is related to the integration of a combined photovoltaic-thermal (PV-T) collector as a component of buildings' facades. This concept is developed so as to determine the best integration strategy—to make the most efficient use of a solar energy-collecting surface in terms of both electrical conversion and air heating, taking into account the fact that thermal effects help to maintain the PV module operating temperature at an optimal level for photovoltaic conversion. To achieve these objectives, one of the key issues is to understand and analyze the coupled physical mechanisms governing the thermal behavior of combined PV-T collectors. In this paper, models describing conduction and radiation heat transfer in a PV module, which govern the thermo-aerodynamics in the air channel, are detailed. For the fluid flow modeling, a low Reynolds number model is applied, and particular attention is paid to the best choice of associated parameters. In the case of a vertical channel heated at one side, a parametric study is performed as a function of the channel width, wall heat flux, and dimensionless turbulent intensity. A preliminary application of the coupled radiation—the natural convection heat transfer problem corresponding to a photovoltaic-thermal collector configuration—is proposed.

On the generation of turbulence with a perforated plate

The root-mean-square of the turbulence velocity fluctuation components, u ′ and v ′, and the integral length scale, L, were measured downstream of a perforated plate inside a wind tunnel test section using a hot-wire anemometer. Nine combinations of three hole diameters ( D=25.4, 38.1 and 50.8 mm) and three plate solidity values ( σ=35%, 50% and 60%) were investigated at three downstream locations ( X=20 D, 30 D and 40 D) for three Reynolds number values (Re = 15,000, 22,000 and 29,000). Over the range of conditions considered, the results indicated that Re had no obvious effect on the normalized turbulence parameters u ′/ U, v ′/ U and L/ D. The dimensionless turbulence intensity decreased with X/ D with a power law relationship, but increased with σ in an exponential fashion over the range of values considered. The plate with a 35% solidity was found to possess the highest degree of homogeneity in terms of the uniformity of the turbulence intensity over any cross-section. The turbulence was more uniform in the region where the corresponding flatness factor, F, of the turbulence fluctuation velocity was approximately equal to 3.

Within Homogeneous Turbulence: Crow Instability Large Eddy Simulation of Aircraft Wake Vortices

Ambient atmospheric turbulence effects on aircraft wake vortices are studied using a validated large eddy simulationmodel. Our results conŽ rm that the most ampliŽ ed wavelength of the Crow instability and the lifetime of wake vortices are signiŽ cantly in uenced by ambient turbulence (Crow, S. C., “Stability Theory for a Pair of TrailingVortices,” AIAA Journal, Vol. 8, No. 12, 1970,pp. 2172–2179). The Crow instabilitybecomeswell developed in most atmospheric turbulence levels, but in strong turbulence the vortex pair deforms more irregularly due to turbulence advection. The most ampliŽ ed wavelength of the instability decreases with increasing dimensionless turbulence intensity , although it increases with increasing turbulence integral length scale. The vortex lifespan is controlled primarily by and decreases with increasing , whereas the effect of integral scale of turbulence on vortex lifespan is of minor importance. The lifespan is estimated to be about 40% larger than Crow and Bate’s predicted value (Crow, S. C., and Bate, E. R., “Lifespan of Trailing Vortices on a Turbulent Atmosphere,” Journal of Aircraft, Vol. 13, No. 7, 1976, pp. 476–482) but in agreement with Sarpkaya’s recent modiŽ cation (Sarpkaya, T., “Decay of Wake Vortices of Large Aircraft,” AIAA Journal, Vol. 36, No. 9, 1998, pp. 1671–1679) to Crow and Bate’s theory. This larger lifespan is also supported by data from water tank experiments and direct numerical simulations. There appears to be a possibility that the scatter in vortex lifespans due to ambient turbulence alone decreases with increasing Reynoldsnumber, whereas larger scatter of lifespans in  ight tests may result from other factors such as stratiŽ cation, wind shear, and inhomogeneous ambient turbulence.

Large eddy simulation of aircraft wake vortices within homogeneous turbulence - Crow instability

Ambient atmospheric turbulence effects on aircraft wake vortices are studied using a validated large eddy simulation model. Our results confirm that the most amplified wavelength of the Crow instability and the lifetime of wake vortices are significantly influenced by ambient turbulence. The Crow instability becomes well developed in most atmospheric turbulence levels, but in strong turbulence the vortex pair deforms more irregularly due to turbulence advection. The most amplified wavelength of the instability decreases with increasing dimensionless turbulence intensity η, although it increases with increasing turbulence integral length scale. The vortex lifespan is controlled primarily by η and decreases with increasing η, whereas the effect of integral scale of turbulence on vortex lifespan is of minor importance

Similarity of heat radiation from turbulent buoyant jets

The thermal radiation similarity of buoyant turbulent jets is studied. The principal condition for the radiation similarity is the similarity of the temperature and the concentration fields in the near-nozzle region because the main part of radiation is generated by this most heated section of the jet. The k- ε- T′ 2 turbulent viscosity model is used to study numerically the gas dynamic similarity in the near-nozzle zone. It is shown that the excess temperature and concentration fields of different jets can be described by a universal function of the dimensionless coordinates that are longitudinal and transverse coordinates normalized with respect to the special longitudinal and transverse scales. It is found, as a result of the gas dynamic similarity, that the dimensionless spectral intensity (normalized with respect to the production of spectral radiance at the edge of the nozzle and the nozzle area) is described by a universal function which is the same for a wide class of jets and which depends on the exit parameters, radiation frequency and on the steepness of the temperature dependence of the absorption coefficient. The results obtained are generalized for the case of molecular gas radiation in finite spectral intervals containing many spectral lines. A simple and effective method for jet radiation prediction, which does not require a detailed information about the jet gas dynamic structure, is developed.