Modeling Time’s Arrow

[Arrow poisons--relics of former times?].

Modeling Time's Arrow

Quantum gravity, the initial low entropy state of the Universe, and the problem of time are interlocking puzzles. In this article, we address the origin of the arrow of time from a cosmological perspective motivated by a novel approach to quantum gravitation. Our proposal is based on a quantum counterpart of the equivalence principle, a general covariance of the dynamical phase space. We discus...

Universal Arrow Foundations for Visual Modeling

The goal of the paper is to explicate some common formal logic underlying various notational systems used in visual modeling. The idea is to treat the notational diversity as the diversity of visualizations of the same basic specificational format. It is argued that the task can be well approached in the arrow-diagram logic framework where specifications are directed graphs carrying a structure...

Mechanical and Mathematical Modeling of Sport Archery Arrow Ballistics

Mechanical and mathematical model of external ballistics of the modern sport bow has been proposed. The force of air drag, shear friction, and drag on the fletching, and the additional force that depends on the angle of attack have been taken into account in the model. The corresponding Cauchy problem was stated and solved using the Runge-Kutta method and the program NDSolve from the software p...

Modeling and prediction of surgical procedure times

Accurate prediction of medical operation times is of crucial importance for cost efficient operation room planning in hospitals. This paper investigates the possible dependence of procedure times on surgeon factors like age, experience, gender, and team composition. The effect of these factors is estimated for over 30 different types of medical operations in two hospitals, by means of ANOVA mod...