Accurate freeway travel time estimates are critical for transportation management and traveler information—both infrastructure-based and in-vehicle. Infrastructure managers are interested in estimating optimal freeway sensor density for new construction and retrofits. This paper describes a concept developed from first principles of traffic flow for establishing optimal sensor density based on ...

The magnitude of personal travel in the industrialised society has increased tremendously. In Sweden, the average travelled distance per person is currently around 40 km per day (see Figure 10.1). Travelling distances are related to speed. Studies show that the time spent on travel tends to be relatively constant at around one hour a day on average. The historical development of new transport t...

Travel restrictions may reduce the spread of a contagious disease that threatens public health. In this study we investigate what effect different levels of travel restrictions may have on the speed and geographical spread of an outbreak of a disease similar to SARS. We use a stochastic simulation model of the Swedish population, calibrated with survey data of travel patterns between municipali...

We present a new method for helioseismic diagnostics of the three-dimensional structure of sound speed, magnetic fields and flow velocities in the convection zone by inversion of acoustic travel-time data. The data are measurements of the time for acoustic waves to travel between points on the solar surface and surrounding annuli obtained from continuous observations at the South Pole in 1991 a...

Recent solutions to the Einstein Field Equations involving negative energy densities, i.e., matter violating the weak-energy-condition, have been obtained, namely traversable wormholes, the Alcubierre warp drive and the Krasnikov tube. These solutions are related to superluminal travel, although locally the speed of light is not surpassed. It is difficult to define faster-than-light travel in g...

Recent solutions to the Einstein Field Equations involving negative energy densities, i.e., matter violating the weak-energy-condition, have been obtained, namely traversable wormholes, the Alcubierre warp drive and the Krasnikov tube. These solutions are related to superluminal travel, although locally the speed of light is not surpassed. It is difficult to define faster-than-light travel in g...