ON THE PROBABILITY OF INFECTION OF A SUSCEPTIBLE NODE FOR THE REED-FROST MODEL

We investigate a model of computer virus propagation based on the Reed-Frost model and the random graph model. A simplified formula for the probability of infection of a susceptible node is obtained, which significantly simplifies the software implementation of the model under consideration. Then a simulation experiment was carried out, which showed that the resulting formula gives a good estimate for the results obtained experimentally.

When Should Agencies Post Weight Limits on Local Highways in New York State?

Most highways in New York State, United States, are maintained by local agencies, so decisions about operations and maintenance for low-volume roads are critical. Local highway officials use existing tools and methods to manage their highway networks. Posting of weight limits is done for a variety of reasons such as: structural limits on bridges, setting of truck routes through a community, and seasonal posting. A simple low-volume pavement model was developed using with the Cornell Pavement Frost Model to review various approaches to seasonal posting of roads and streets. Using a simple model for timing of seasonal posting can be a very effective tool for a local highway agency. The Cornell Local Roads Program developed such a spreadsheet tool currently being tested by local towns in New York State. The tool only requires a simple pavement model and average air temperature data.

A Simple Frost Model for Calculation of the Frost Thickness over Ground Aircraft Surfaces

In this study, a simple model that describes frost formation over ground aircraft surfaces is presented. The model uses the data of the aircraft surface temperature, air temperature and air velocity to predict the frost thickness. The frost surface temperature and the frost thickness under different atmospheric conditions are investigated. The results indicate the frost thickness increases with the air velocity and the air temperature, decrease with the surface temperature. This model enables forecast of the frost formation over ground aircraft surface.

The Frost Model of Concrete in the View of Damage Mechanics

To propose the damage model of concrete in the freezing-thawing cycles, the reasonable dissipation function and micro plastic deformation expression have been determined based on the continuum damage mechanics. The damage variable is expressed as a function of the number of freezing-thawing cycle. The damage is defined in terms of the loss of the dynamic elastic modules and the damage model of the concrete in the freezing-thawing cycles has been presented.

VARIABILITY FOR CARRIER-BORNE EPIDEMICS AND REED–FROST MODELS INCORPORATING UNCERTAINTIES AND DEPENDENCIES FROM SUSCEPTIBLES AND INFECTIVES

This article provides analytical results on which are the implications of the statistical dependencies among certain random parameters on the variability of the number of susceptibles of the carrier-borne epidemic model with heterogeneous populations and of the number of infectives under the Reed–Frost model with random infection rates. We consider dependencies among the random infection rates, among the random infectious times, and among random initial susceptibles of several carrier-borne epidemic models. We obtain conditions for the variability ordering between the number of susceptibles for carrier-borne epidemics under two different random environments, at any time-scale value. These results are extended to multivariate comparisons of the random vectors of populations in the strata. We also obtain conditions for the increasing concave order between the number of infectives in the Reed–Frost model under two different random environments, for any generation. Variability bounds are obtained for different epidemic models from modeling dependencies for a range of special cases that are useful for risk assessment of disease propagation.