Improvement of Network Flow Using Multi-Commodity Flow Problem

In recent years, Internet traffic has increased due to its widespread use. This can be attributed to the growth of social games on smartphones and video distribution services with increasingly high image quality. In these situations, a routing mechanism is required to control congestion, but most existing routing protocols select a single optimal path. This causes the load to be concentrated on certain links, increasing the risk of congestion. In addition to the optimal path, the network has redundant paths leading to the destination node. In this study, we propose a multipath control with multi-commodity flow problem. Comparing the proposed method with OSPF, which is single-path control, and OSPF-ECMP, which is multipath control, we confirmed that the proposed method records higher packet arrival rates. This is expected to reduce congestion

Permeation of gases through polymer membranes investigated by mass spectroscopy

A new method to estimate permeation coefficients for small sized polymer samples is introduced. It uses a mass spectrometer to measure the partial pressure of gas permeating from an enclosed volume of gas as a function of time. In agreement with predictions from a simple model the partial pressure varies exponentially with time. From the time constant and the geometry of the gas cell it is possible to calculate the permeation coefficient for individual species in gas mixtures. The mass spectrometric estimated permeation coefficients are in reasonable agreement with control experiments and data from the literature. (C) 1999 Elsevier Science Ltd. All rights reserved