33 research outputs found
Kinetics for Desiccator, Jar and Alike Tests for Formaldehyde Release from Particleboard
A kinetic equation linking test results with test parameters was derived for testing particleboard for formaldehyde release by means of a desiccator, jar, WKI, and similar tests based on undisturbed diffusion of formaldehyde from the board surface through the air into water. The equation was assessed by means of some experimental observations such as the independence of results on the number of test specimens and the asymptotic convergence of results obtained by different methods at increased temperature
Radiation from a charge circulating inside a waveguide with dielectric filling
The emitted power of the radiation from a charged particle moving uniformly
on a circle inside a cylindrical waveguide is considered. The expressions for
the energy flux of the radiation passing through the waveguide cross-section
are derived for both TE and TM waves. The results of the numerical evaluation
are presented for the number of emitted quanta depending on the waveguide
radius, the radius of the charge rotation orbit and dielectric permittivity of
the filling medium. These results are compared with the corresponding
quantities for the synchrotron radiation in a homogeneous medium.Comment: 10 pages, Latex, four EPS figure
Synchrotron radiation from a charge moving along a helical orbit inside a dielectric cylinder
The radiation emitted by a charged particle moving along a helical orbit
inside a dielectric cylinder immersed into a homogeneous medium is
investigated. Expressions are derived for the electromagnetic potentials,
electric and magnetic fields, and for the spectral-angular distribution of
radiation in the exterior medium. It is shown that under the Cherenkov
condition for dielectric permittivity of the cylinder and the velocity of the
particle image on the cylinder surface, strong narrow peaks are present in the
angular distribution for the number of radiated quanta. At these peaks the
radiated energy exceeds the corresponding quantity for a homogeneous medium by
some orders of magnitude. The results of numerical calculations for the angular
distribution of radiated quanta are presented and they are compared with the
corresponding quantities for radiation in a homogeneous medium. The special
case of relativistic charged particle motion along the direction of the
cylinder axis with non-relativistic transverse velocity (helical undulator) is
considered in detail. Various regimes for the undulator parameter are
discussed. It is shown that the presence of the cylinder can increase
essentially the radiation intensity.Comment: 18 pages, 8 EPS figure
Electromagnetic field and radiation for a charge moving along a helical trajectory inside a waveguide with dielectric filling
We investigate the electromagnetic field generated by a point charge moving
along a helical trajectory inside a circular waveguide with conducting walls
filled by homogeneous dielectric. The parts corresponding to the radiation
field are separated and the formulae for the radiation intensity are derived
for both TE and TM waves. It is shown that the main part of the radiated quanta
is emitted in the form of the TE waves. Various limiting cases are considered.
The results of the numerical calculations show that the insertion of the
waveguide provides an additional mechanism for tuning the characteristics of
the emitted radiation by choosing the parameters of the waveguide and filling
medium.Comment: 17 pages, 9 figures, discussion, graphs, and references adde
Expected properties of the Two-Point Autocorrelation Function of the IGM
Recent analyses of the fluctuations of the soft Diffuse X-ray Background
(DXB) have provided indirect detection of a component consistent with the
elusive Warm Hot Intergalactic Medium (WHIM). In this work we use theoretical
predictions obtained from hydrodynamical simulations to investigate the angular
correlation properties of the WHIM in emission and assess the possibility of
indirect detection with next-generation X-ray missions. Our results indicate
that the angular correlation signal of the WHIM is generally weak but dominates
the angular correlation function of the DXB outside virialized regions. Its
indirect detection is possible but requires rather long exposure times [0.1-1]
Ms, large (~1{\deg} x1{\deg}) fields of view and accurate subtraction of
isotropic fore/background contributions, mostly contributed by Galactic
emission. The angular correlation function of the WHIM is positive for {\theta}
< 5' and provides limited information on its spatial distribution. A
satisfactory characterization of the WHIM in 3D can be obtained through
spatially resolved spectroscopy. 1 Ms long exposures with next generation
detectors will allow to detect ~400 O VII+O VIII X-ray emission systems that we
use to trace the spatial distribution of the WHIM. We predict that these
observations will allow to estimate the WHIM correlation function with high
statistical significance out to ~10 Mpc h^-1 and characterize its dynamical
state through the analysis of redshift-space distortions. The detectable WHIM,
which is typically associated with the outskirts of virialized regions rather
than the filaments has a non-zero correlation function with slope {\gamma} =
-1.7 \pm 0.1 and correlation length r0 = 4.0 \pm 0.1 Mpc h^-1 in the range r =
[4.5, 12] Mpc h^-1. Redshift space distances can be measured to assess the
dynamical properties of the gas, typically infalling onto large virialized
structures.Comment: 17 pages, 2 tables, 11 figures, Final version, accepted for
publication on MNRA
A convolution integral representation of the thermal Sunyaev-Zel'dovich effect
Analytical expressions for the non-relativistic and relativistic
Sunyaev-Zel'dovich effect (SZE) are derived by means of suitable convolution
integrals. The establishment of these expressions is based on the fact that the
SZE disturbed spectrum, at high frequencies, possesses the form of a Laplace
transform of the single line distortion profile (structure factor).
Implications of this description of the SZE related to light scattering in
optically thin plasmas are discussed.Comment: 11 pages, 2 figures. Accepted for publication in J. Phys.
Gravitational Waves from Hyper-Accretion onto Nascent Black Holes
We examine the possibility that hyper-accretion onto newly born, black holes
occurs in highly intermittent, non-asymmetric fashion favorable to
gravitational wave emission in a neutrino cooled disk. This picture of
near-hole accretion is motivated by magneto-rotationally induced,
ultra-relativistic disk dynamics in the region of the flow bounded from below
by the marginally bound geodesic radius. For high spin values, a largely
coherent magnetic field in this region has the dynamical implication of compact
mass segregation at the displacement nodes of the non-axisymmetric, MRI modes.
When neutrino stress competes favorably for the disk dynamical structure, the
matter clumps may be rather dense and sufficiently long-lived to excite the
Quasi-Normal Ringing (a.k.a. QNR) modes of the Kerr geometry upon their
in-fall. We find that such accretion flow may drive bar-like, quadrupole
(l,m=2,2) modes in nearly resonant fashion for spin parameters . The
ensuing build up in strain amplitude of the undamped oscillations warrants a
brisk rate of energy deposition into gravitational waves. A detectability
assessment for the LIGO interferometers through the match filtering technique
is given by integrating the energy flux over a one second epoch of resonant
hyper-accretion at 1 \msun \sec^{-1}. Thus, a 15 \msun Kerr black hole
spinning at ( Hz), and located at 27
Mpc (e.g., GRB980425), will deliver a characteristic strain amplitude, , large enough to be detectable by LIGO II. If resonant
hyper-accretion were sustainable for a longer period (or at higher rates)
possibly associated with a second broad hump in a GRB light-curve, these
objects could be detected by LIGO I at very low redshifts.Comment: 12 pages, 4 figures, M.N.R.A.S. submissio
Flash point of binary mixtures of chlorinated hydrocarbons with toluene and their predictability with existing mixing rule
The flash points of binary mixtures of toluene with two chlorinated hydrocarbons (trichloroethylene and dichloromethane) at different concentrations were investigated to evaluate their predictability by existing mixing rules. Measurements were performed using both open and closed cup flash point testers highlighting complex ignition phenomena. Beyond a certain level of concentration in chlorinated compound, no proper flash is observed, in our test conditions when the flame is presented, but specific behaviors are observed that did not allow the definitive determination of a flash point. The observed phenomena can be attributed to the formation of halogenated radicals, presenting flame-retardant behaviors, by decomposition of the chlorinated vapors at the contact of the flame. Existing mixing rules are based on the consideration of the vapor-liquid equilibrium defining the amount of flammable vapors above the liquid surface. So, the application of such mixing rule failed predicting this specific phenomenon, more likely related to a specific reactivity problem. This work also confirms that the sole consideration of the flash point to investigate the flammability of such mixtures may lead to an underestimation of their actual hazard. Additional experimental tests should be conducted to investigate deeper the flammability of such liquid mixtures