Relative permeability measurements for two phase flow in unconsolidated sands

This paper presents the results of laboratory measurements of relative permeability for two phase flow in partially saturated samples of unconsolidated sands. Relative permeabilities for tap water and air, de-aired water and nitrogen were measured using a steady—state technique. Three different sand samples (fine sand, heterogeneous sand and coarse sand) were tested.     

Calculation of the integral parameters of rotor-type granulators

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 4, p. 19, April, 1992.     

Analysis of a complexity-based pruning scheme for classification trees

A complexity-based pruning procedure for classification trees is described, and bounds on its finite sample performance are established. The procedure selects a subtree of a (possibly random) initial tree in order to minimize a complexity penalized measure of empirical risk. The complexity assigned to a subtree is proportional to the square root of its size. Two cases are considered. In the first, the growing and pruning data sets are identical, and in the second, they are independent Using the performance bound, the Bayes risk consistency of pruned trees obtained via the procedure is established when the sequence of initial trees satisfies suitable geometric and structural constraints. The pruning method and its analysis are motivated by work on adaptive model selection using complexity regularization.     

The evolution and development of the urinary catheter

The urinary catheter is one of the most frequently used medical devices and has a long and intriguing history of development. This paper describes the catheter from its simple beginnings through the subtle but important changes it has undergone paralleling the advances in plastics technology witnessed this century. The changes have not been without controversy and the recent association of catheters with tissue toxicity, which has forced the implementation of strict guidelines for their manufacture and use, is described.     

Computer aided instruction of rotating electric machines viaanimated graphics

A menu-driven interactive graphics software package has been developed for use as an instructional aid for the electric machines course in the electrical engineering curriculum. The main purpose of this tool is to give the students a clearer understanding of the basics of the operation of rotating electric machines. The animation program was developed for displaying live and rotating diagrams depicting different modes of operation of synchronous generators. Different parts are identified with different colors. The interaction of the magnetic poles on the stator and on the rotor, and the relative spatial positions and time variations of the magnetic and electric quantities are demonstrated through moving images. The software features are described     

Restenosis and arterial remodelling after coronary angioplasty

Restenosis after coronary angioplasty (PTCA) is a complex process and is still the major problem, despite improvements in equipment and technique. Thrombus formation and intimal hyperplasia have been considered to be the main causes of the development of restenosis after primary successful angioplasty. As yet, pharmacological trials to prevent restenosis have failed to prevent it, despite the fact that the therapy has been aimed at reducing thrombus formation and intimal hyperplasia. Several new angioplasty devices have been developed. Series of observations and a few controlled trials have demonstrated restenosis rates similar to those obtained with conventional balloon angioplasty, except in the case of stent implantation, which appears to be promising. Intravascular ultrasound studies have provided new insight and a more complete understanding of the process leading to restenosis. Vascular remodeling is now considered as an important pathogenetic factor. It consists of a change in the cross-sectional vessel area and may involve an actual constriction of the artery. This may lead to lumen-narrowing and finally restenosis with minimal neointimal formation. In this review we summarise the literature on the restenosis process and the current status of the clinical trials aimed at preventing restenosis.