8,003 research outputs found
Gas mass-flow meters: Principles and applications
Gas mass-flow meters (GMFM) for original equipment manufacturers (OEM) applications are presently found in a relatively easy and cheap way. GMFM may be applied in a number of
different situations but technical formation concerning its principles of measurement and
applications are still misleading.
In this paper, the principles of GMFM measurement are discussed and the operating
parameters are clarified. A concept of gas mass-flow response factor is introduced and
further used in a model for gas mass-flow measurement that is suitable to any gas mixture of known composition.
In addition, a model for the application of GMFM to dynamic volumetric methods of dilution is presented and generalized
Dark-ages Reionization and Galaxy Formation Simulation -- XIX: Predictions of infrared excess and cosmic star formation rate density from UV observations
We present a new analysis of high-redshift UV observations using a
semi-analytic galaxy formation model, and provide self-consistent predictions
of the infrared excess (IRX) -- relations and cosmic star formation
rate density. We combine the Charlot & Fall dust attenuation model with the
Meraxes semi-analytic model, and explore three different parametrisations for
the dust optical depths, linked to star formation rate, dust-to-gas ratio and
gas column density respectively. A Bayesian approach is employed to
statistically calibrate model free parameters including star formation
efficiency, mass loading factor, dust optical depths and reddening slope
directly against UV luminosity functions and colour-magnitude relations at z ~
4-7. The best-fit models show excellent agreement with the observations. We
calculate IRX using energy balance arguments, and find that the large intrinsic
scatter in the IRX - plane is driven by the specific star formation
rate. Additionally, the difference among the three dust models suggests a
factor of two systematic uncertainty in the dust-corrected star formation rate
when using the Meurer IRX - relation at z > 4.Comment: 15 pages, 10 figure. Accepted for publication in MNRA
Coupled effects of local movement and global interaction on contagion
By incorporating segregated spatial domain and individual-based linkage into
the SIS (susceptible-infected-susceptible) model, we investigate the coupled
effects of random walk and intragroup interaction on contagion. Compared with
the situation where only local movement or individual-based linkage exists, the
coexistence of them leads to a wider spread of infectious disease. The roles of
narrowing segregated spatial domain and reducing mobility in epidemic control
are checked, these two measures are found to be conducive to curbing the spread
of infectious disease. Considering heterogeneous time scales between local
movement and global interaction, a log-log relation between the change in the
number of infected individuals and the timescale is found. A theoretical
analysis indicates that the evolutionary dynamics in the present model is
related to the encounter probability and the encounter time. A functional
relation between the epidemic threshold and the ratio of shortcuts, and a
functional relation between the encounter time and the timescale are
found
- …