Showing papers by "École Polytechnique de Montréal published in 1973"

Reinforced earth retaining walls

Abstract: Reinforced earth is a man-made earth fill in which thin bars, rods, fibers, or nets have been placed to improve the overall qualities of the soil This paper describes the results of analytical and laboratory studies on small reinforced earth retaining walls Experimental data were compared to analytical solutions for wall failure by either pullout or breaking of the reinforcing elements, and found to be in reasonable agreement Cost estimates for prototype structures suggest that the cost of reinforced earth could be as low as half the cost of other conventional earth retaining walls

A Graph-Theoretic Equivalence for Integer Programs

Abstract: This paper is concerned with the relation between 0-1 integer programs and graphs. An equivalence is established between solving 0-1 integer programs with quadratic or linear objective functions and solving a cut problem on a related graph.

Dynamic High Temperature Microwave Complex Permittivity Measurements on Samples Heated Via Microwave Absorption

Abstract: A new dynamic method for measuring the dielectric constant and the dielectric loss tangent (tan 8), of spherical or rod shaped test samples at either low (below 0°C) or high temperatures (1500°C) is described. Experimental results for glass-bonded mica (Mycalex), steatite ceramic (Centralab type 302), borosilicate glass (Corning 7740), and Iron sulfide (FeS) are given for temperatures varying from room temperature up to 600°C. The test samples are heated by microwave energy inside a cavity resonator which has two dominant modes. One of these resonances is used for heating the sample at the ISM frequency of 2.45 GHz whereas the second resonance is used for measuring the dielectric properties. Cavity test cells suitable for either spherical or rod shaped samples are described. The experimental results obtained are in general agreement with results published in the literature.

Refractometer associated with the fabry-perot spectrometer.

Abstract: This paper describes the principles, realization, and characteristics of a refractometer used as a reference for measuring the scanning of a high resolution, photoelectric Fabry-Perot spectrometer. The precision of the measurements on this refractometer is approximately one order of magnitude greater than that obtainable with other instruments.

Étude spectrophotométrique des produits formés au cours de l'oxydation superficielle du titane et de l'alliage TA6V

Abstract: Resume Les produits formes au cours de l'oxydation, entre 400 et 650 °C, du titane et de l'alliage TA6V ont ete etudies par reflexion diffuse. Les oxydes de formule generale Ti n O 2 n − 1 sont formes successivement au cours du temps. L'oxyde TiO ( n = 1) est situe au contact de la phase metallique et les oxydes correspondant a des valeurs de n superieures assurent le contact avec la phase gazeuse. Plus la couche formee est epaisse, plus la valeur de n correspondant a l'oxyde externe est grande. Des que cette couche devient suffisamment epaisse l'oxyde externe est le rutile TiO 2 .

Microwave Curing of Synthetic Rubbers

Abstract: It is shown that the microwave absorption characteristics of compounds based on a given polymer can be controlled by incorporating suitable compounding ingredients, even if the polymer itself absorbs microwave energy only weakly. On the basis of ten different application-oriented compound formulations it is shown that the quality of microwave-cured rubber is comparable to that of conventionally vulcanized material. Correlations between dielectric measurements at microwave frequencies and curing tests show that the suitability of a given material for microwave curing can be determined from knowledge of the dielectric loss factor and its temperature variation. Finally, various advantages of the slow-wave structure apparatus used in this study are pointed out.

Friction reduction by chemical additives in the turbulent flow of fibre suspensions

Abstract: The effect of friction reducing additives on the turbulent flow characteristics of fibre suspensions have been studied experimentally by using a small diameter straight tube and a free rotating disk. The fibre concentration varied between 0.1 and 5.0%. The friction reducing additives were polyethylene oxide and guar gum. The optimum conditions for friction reduction and effects of temperature, aging and mechanical degradation have been determined; the viscoelastic behaviour of fibre suspensions with and without additives have also been studied. It is shown that the use of friction reducing additives in the turbulent flow of paper making fibre suspensions results in a friction reduction comparable to that in water and the quality of fibre suspensions can be improved. On a etudie experimentalement leffet que produisent les additifs servant a diminuer le frottement sur les caracteristiques dun ecoulement turbulent de suspensions de fibres; on a employe a cette fin un tube droit de faible diametre et un disque tournant librement. La concentration des fibres a varie entre 0.1% et 5.0%. Les additifs utilises ont ete loxyde de poly ethylene et la gomme guar. On a determine les conditions optimales pour la diminution du frottement ainsi que les effets de la temperature, du vieillissement et de la degradation mecanique; on a etudie egalement le comportement visco-elastique des suspensions de fibre, en presence et en labsence des additifs precites. On a constate que lemploi dadditifs pour diminuer le frottement dans lecoulement turbulent de fibres en suspension (qui servent a la fabrication du papier) produit une diminution du frottement comparable a celle dans leau et permet dameliorer les suspensions de fibres.

A Digital Non-Contact Microwave Instrument for Egg Size and Shape Index Measurements

Abstract: An instrument is described which measures the size of an egg by means of a non-contact microwave transducer. By a single frequency count it is possible to classify an egg in one of the four standard grades: extra large, large, medium, and small. Such measurements can be made, by an electronic counter, with the egg moving at conveyor belt speeds of up to 300 feet per minute. In this case the eggs must be at least six inches apart. The egg shape index may also be measured by taking two separate frequency counts as described in this paper.

Causality for nonlinear systems in Hilbert spaces

Abstract: This paper is about the causality structure of systems in Hilbert spaces. While treatments on the subjects are usually confined to systems which enjoy properties such as linearity, boundedness, or nonpredictive behavior, here, all these properties play no essential role. As a consequence, new and more general results are obtained. These results concern the concepts of causality, anticausality, and crosscausality, and give necessary and sufficient conditions to decompose a general system into the sum of causal, anticausal, and crosscausal components.

Electrooptical Fabry-Perot Spectroscopy

Abstract: A new method is described that uses an elegtronic imaging tube to record and explore Fabry-Perot fringes. The light intensity distribution of an interference pattern and the Doppler effect of a line can be observed with an exploration time of the order of 10−5 sec. Some important applications in the fields of spectroscopy and education are also considered.