Fluid-dynamical and microscopic description of traffic flow: a data-driven comparison

A lot of work has been done to compare traffic flow models with reality; so far, this has been done separately for microscopic as well as for fluid-dynamical models of traffic flow. This paper compares directly the performance of both types of models to real data. The results indicate, that microscopic models on average seem to have a tiny advantage over fluid-dynamical models, however one may admit that for most applications the differences between the two are small. Furthermore, the relaxation time of the fluid-dynamical models turns out to be fairly small, of the order of two seconds, and are comparable with the results for the microscopic models. This indicates that the second order terms are weak, however, the calibration results indicate that the speed equation is in fact important and improves the calibration results of the models

How human drivers control their vehicle

The data presented here show that human drivers apply a discrete noisy control mechanism to drive their vehicle. A car-following model built on these observations, together with some physical limitations (crash-freeness, acceleration), led to non-Gaussian probability distributions in the speed difference and distance which are in good agreement with empirical data. All model parameters have a clear physical meaning and can be measured. Despite its apparent complexity, this model is simple to understand and might serve as a starting point to develop even quantitatively correct models.Comment: 5 pages, 6 figures, submitted to PR

Sensitivity of life disparity with respect to changes in mortality rates

This article is concerned with sensitivity analysis of life disparity with respect to changes in mortality rates. A relationship is derived that describes the effect on life disparity caused by a perturbation of the force of mortality. Recently Zhang and Vaupel introduced a "threshold age", before which averting deaths reduces disparity, while averting deaths after that age increases disparity. I provide a refinement to this result by characterizing the ages at which averting deaths has an extremal impact on life disparity. The results are illustrated using data for the female populations of Denmark in 1835, and for the United States in 2005.life disparity, mortality analysis, sensitivity analysis, threshold age

Prospects of Searches for Neutral, Long-Lived Particles which Decay to Photons using Timing at CDF

We present the prospects of searches for neutral, long-lived particles which decay to photons using their time of arrival measured with a newly installed timing system on the electromagnetic calorimeter (EMTiming) of the Collider Detector at Fermilab (CDF). A Monte Carlo simulation shows that EMTiming can provide separation between decay photons from particles with both a long lifetime and a low boost, and prompt photons from Standard Model backgrounds. Using a gauge mediated supersymmetry breaking (GMSB) $\tilde{\chi}_{1}^{0}\to\gamma\tilde{G}$ model we estimate a quasi-model-independent sensitivity using only direct neutralino pair production, and also estimate the expected 95% confidence level exclusion regions for all superpartner production as a function of the neutralino mass and lifetime. We find that a combination of single photon and diphoton analyses should allow the Tevatron in run II to easily extend the exclusion regions from LEP II at high neutralino masses and lifetimes, and cover much, if not all, of the theoretically favored $m_{\tilde{G}}$ < 1 keV/c^2 parameter space for neutralino masses less than 150 GeV/c^2.Comment: 15 pages, 21 figures; to be submitted to Phys. Rev.

Effects of anticipatory driving in a traffic flow model

Anticipation in traffic means that drivers estimate their leaders' velocities for future timesteps. In the article a specific stochastic car--following model with non--unique flow--density relation is investigated with respect to anticipatory driving. It is realized by next--nearest--neighbour interaction which leads to large flows and short temporal headways. The underlying mechanism that causes these effects is explained by the headways of the cars which organize in an alternating structure with a short headway following a long one, thereby producing a strong anti-correlation in the gaps or in the headways of subsequent cars. For the investigated model the corresponding time headway distributions display the short headways observed in reality. Even though these effects are discussed for a specific model, the mechanism described is in general present in any traffic flow models that work with anticipation.Comment: 8 pages, 11 figure

At Ease with Your Warnings: The Principles of the Salutogenesis Model Applied to Automatic Static Analysis

The results of an automatic static analysis run can be overwhelming, especially for beginners. The overflow of information and the resulting need for many decisions is mentally tiring and can cause stress symptoms. There are several models in health care which are designed to fight stress. One of these is the salutogenesis model created by Aaron Antonovsky. In this paper, we will present an idea on how to transfer this model into a triage and recommendation model for static analysis tools and give an example of how this can be implemented in FindBugs, a static analysis tool for Java.Comment: 5 pages, 4 figure