An approach based on spheropolygons (i.e., the Minkowski sum of a polygon with N vertices and a disk with spheroradius r) is presented to describe the shape of kaolinite aggregates in water and to investigate interparticle collision dynamics. Spheropolygons generated against images of kaolinite aggregates achieved an error between 0.5% and 20% as compared to at least 32% of equivalent spheres. ...

In this work, collisions between rotating atomic clusters composed of Lennard-Jones (LJ(n)) particles and an identical projectile have been investigated by means of trajectory simulations as a function of the cluster angular momentum J and internal energy E, and for different values of the projectile impact parameter b and relative velocity v(p). As expected, the collision (P(c)(b)) and capture...

The general quasi-classical treatment for collision-induced vibrational transitions in diatomic molecules, under near-adiabatic conditions, is used to derive quantum corrections for probabilities, calculated in the external field approximation originally used by Landau and Teller. The quantum corrections are expressed through the Landau-Teller classical collision time. The first-order correctio...

We study signal-space coding for coherent slow frequency-hopped communications over a Gaussian multiple-access collision channel (G-MACC). We de ne signal sets and interleavers having maximum collision resistance. The packet-error probability and the spectral e ciency obtained by these signal sets concatenated with outer block coding and hard (error-only) decoding is evaluated without assuming ...

In wireless local area networks, management decisions concerning channel selection, rate selection, and power management have a profound impact on the throughput performance, particularly in dense areas. These measurements, however, are too weakly associated with the MAC layer to be able to make such management decisions. Therefore, direct measurements of the channel quality at the MAC layer ar...

Hash functions are used in authentication and cryptography, as well as for the efficient storage and retrieval of data using hashed keys. Hash functions are susceptible to undesirable collisions. To design or choose an appropriate hash function for an application, it is essential to estimate the probabilities with which these collisions can occur. In this paper we consider two problems: one of ...

This paper presents a new distinguisher which can be applied to secret-prefix MACs with the message length prepended to the message before hashing. The new distinguisher makes use of a special truncated differential path with high probability to distinguish an inner near-collision in the first round. Once the inner near-collision is detected, we can recognize an instantiated MAC from a MAC with...

Nowadays IEEE 802.11 wireless local area networks (WLANs) support multiple transmission rates. To achieve the best performance, transmitting stations adopt the various forms of automatic rate fallback (ARF). However, ARF suffers from severe performance degradation as the number of transmitting stations increases. In this paper, we propose a new rate adaptation scheme which adjusts the ARF’s up/...

This report develops a probabilistic model for analyzing longitudinal collision/safety between an abruptly decelerating vehicle and its immediate follower on an Automated Highway System. The input parameters are the distance between the two vehicles, their common speed prior to the failure, the reaction delay of the following vehicle and a bivariate distribution for the two deceleration rates. ...