Papers by Yannis Drossinos
Aerosol Science and Technology
Aerosol Science and Technology, Apr 13, 2020
EPL (Europhysics Letters)
Linear binary fragmentation of synthetic fractal-like agglomerates composed of spherical, equal-s... more Linear binary fragmentation of synthetic fractal-like agglomerates composed of spherical, equal-size, touching monomers is numerically investigated. Agglomerates of different morphologies are fragmented via random bond removal. The fragmentation algorithm relies on mapping each agglomerate onto an adjacency matrix. The numerically determined fragment size distributions are U-shaped, clusters break predominantly into two largely dissimilar fragments, becoming more uniform as the fractal dimension decreases. A symmetric beta distribution reproduces the fragment distribution rather accurately. Its exponent depends on the structure (fractal dimension) and number of monomers of the initial agglomerate. A universal fragment distribution, a function only of the initial fractal dimension, is derived by requiring that it satisfy the fragmentation conversation laws and the straight-chain limit. We argue that the fragmentation rate is proportional to the initial agglomerate size.
Environmental Research
Light-duty vehicle emission regulation in the European Union requires the dilution of the whole e... more Light-duty vehicle emission regulation in the European Union requires the dilution of the whole exhaust in a dilution tunnel with constant volume sampling prior to emission measurements. This methodology avoids measurement uncertainties associated with direct raw exhaust emission measurements from the tailpipe, such as exhaust flow determination, exhaust flow pressure pulsations, differences in the response time between exhaust flow and instrument signals, or their misalignment. Transfer tubes connecting the tailpipe to the dilution tunnel of different lengths, and mixing of the exhaust gas with the dilution air in the dilution tunnel may increase differences in measurements performed at different facilities. Recently, the light-duty vehicle regulation was complemented by on-road measurements with Portable Emissions Measurement Systems (PEMS). PEMS measurements are conducted from the vehicle tailpipe. Differences between tailpipe and full dilution tunnel measurements have not been adequately addressed so far. In this study we compare particle number emissions measured at the full dilution tunnel or directly at the tailpipe. The measurements covered solid particles with diameter larger than 23 nm, as required by the current regulation, but also solid particles larger than 10 nm, as recommended for future regulations. The studied vehicle technologies were diesel, gasoline, and compressed natural gas. The differences between tailpipe and dilution tunnel particle number emissions were found to be small (< 15%) for both size ranges, with the exception of engine cold start (up to 35% in some cases). Theoretical estimates showed that agglomeration in the transfer line from the vehicle to the dilution tunnel might reduce particle concentrations by up to 17%. Exhaust flow rate determination and time misalignment of exhaust flow and particle concentration signals can introduce uncertainties of ± 10% and ± 5%, respectively, to the tailpipe measurements. The results suggest that tailpipe sampling is not only possible, but it can additionally give more representative ("real") emissions of the vehicle and should be considered in post Euro 6 regulations.
Nuclear Technology
The Energy Citations Database (ECD) provides access to historical and current research (1948 to t... more The Energy Citations Database (ECD) provides access to historical and current research (1948 to the present) from the Department of Energy (DOE) and predecessor agencies.
Thesis Harvard University 1989 Source Dissertation Abstracts International Volume 50 08 Section B Page 3524, 1989
Http Dx Doi Org 10 1080 02786829808965545, Jun 13, 2007
Physical Review E, Apr 1, 2001
The consequences of spontaneously broken translational invariance on the nucleation-rate statisti... more The consequences of spontaneously broken translational invariance on the nucleation-rate statistical prefactor in theories of first-order phase transitions are analyzed. A hybrid, semiphenomenological approach based on field-theoretic analyses of condensation and modern density-functional theories of nucleation is adopted to provide a unified prescription for the incorporation of translational-invariance corrections to nucleation-rate predictions. A connection between these theories is obtained starting from a quantum-mechanical Hamiltonian and using methods developed in the context of studies on Bose-Einstein condensation. An extremum principle is used to derive an integro-differential equation for the spatially nonuniform mean-field order-parameter profile; the appropriate order parameter becomes the square root of the fluid density. The importance of the attractive intermolecular potential is emphasized, whereas the repulsive two-body potential is approximated by considering hard-sphere collisions. The functional form of the degenerate translational eigenmodes in three dimensions is related to the mean-field order parameter, and their contribution to the nucleation-rate prefactor is evaluated. The solution of the Euler-Lagrange variational equation is discussed in terms of either a proposed variational trial function or the complete numerical solution of the associated boundary-value integro-differential problem. Alternatively, if the attractive potential is not explicitly known, an approach that allows its formal determination from its moments is presented.
AIP Conference Proceedings, 2000
A connection between field-theoretic descriptions of condensation and density-functional theories... more A connection between field-theoretic descriptions of condensation and density-functional theories of nucleation is established. The time-independent differential equation for the density profile of a liquid droplet that mediates the transition from liquid to gas phase is derived based on a variational principle. The droplet profile depends crucially on an attractive interaction term. A physically motivated form for the one-dimensional droplet
![Research paper thumbnail of Erratum to: “Dynamical barrier for the formation of solitary waves in discrete lattices” [Phys. Lett. A 372 (2008) 2247]](https://attachments.academia-assets.com/69609751/thumbnails/1.jpg)
Physics Letters A, 2008
After the acceptance of this manuscript, it was brought to our attention that the problem of form... more After the acceptance of this manuscript, it was brought to our attention that the problem of formation of localized modes in 1d DNLS chains was considered in [M.I. Molina, G. Tsironis, Physica D 65 (1993) 267] (see also their work on linear chains with impurities in [M.I. Molina, G. Tsironis, Phys. Rev. B 47 (1993) 15330]). This work considered predominantly few site chains (analytically and numerically), but also numerically examined longer (100-site) chains and its numerical findings for the latter case are consonant with the threshold proposed herein. We thank Professor Mario Molina for bringing these references to our attention. Additional change At the end of the acknowledgements section: A.S. gratefully acknowledges support from NSF-DMS-0701802. ✩ Due to a technical problem the corrections mentioned in this Erratum have not been incorporated in the original article.
SAE International Journal of Engines, 2010
ABSTRACT Euro 5/6 light-duty vehicle emissions regulation introduced non-volatile particle number... more ABSTRACT Euro 5/6 light-duty vehicle emissions regulation introduced non-volatile particle number emission measurements. The particle number measurement system consists of a volatile removal unit followed by a particle number counter with a 50% cut-point diameter ...
Physical Review E, 2009
Important features associated with the segregration of particles in turbulent flow are investigat... more Important features associated with the segregration of particles in turbulent flow are investigated by considering the statistical distribution (phase-space number density) of particles subject to the combined effects of straining flow and stochastic forcing. A Fokker-Planck model is used to obtain results for the phase-space distributions of particles that are entrained into straining flow fields. The analysis shows that, in marked contrast to the zero strain case, nonsingular steady-state distributions are generated, and also confirms that the diffusional effect resulting from stochastic forcing is sufficient to offset the otherwise singular distributions that would result from the indefinite accumulation of particles along stagnation lines. The influence of particle inertia (Stokes number) on the form of the resulting distributions is considered and several significant results are observed. The influence of strain rate on the attenuation of particle kinetic stresses is quantified and explained. The development of large third-order velocity moments is observed for Stokes numbers above a critical value. The mechanism underlying this phenomenon is seen to be a generic feature of particle transport in flows where vortex structures induce local counterflows of particles. The system therefore provides an ideal test for closure models for third-order moments of particle velocities, and here the standard Chapman-Enskog approximation is assessed.
Journal of Nuclear Materials, 1999
Metallic silver and iodine form insoluble AgI in the containment sump which has a major impact on... more Metallic silver and iodine form insoluble AgI in the containment sump which has a major impact on iodine volatility and hence on the source term to the environment. Resistance-in-series models are developed and validated against separate-effects tests. The reaction between I2 and Ag is limited by mass transfer in the liquid. The rate does not follow a parabolic law for
The Journal of Chemical Physics, 1999
Two different methods to calculate the steady-state nucleation rate in heteromolecular systems pr... more Two different methods to calculate the steady-state nucleation rate in heteromolecular systems proposed by Stauffer (1976) and Langer (1969) are analyzed. Their mathematical equivalence is explicitly demonstrated, thereby obtaining a generic expression for the rate of binary nucleation. Its numerical evaluation does not entail rotation of the coordinate system at the saddle point, but it only requires data in the
Uploads
Papers by Yannis Drossinos