Topological Modeling of a One Stage Spur Gear Transmission

Finding a basis of unification for the modeling of mechatronic systems is the search subject of several works.This paper is a part of a general research designed to the application of topology as a new approach for the modeling of mechatronic systems.Particularly,the modeling of a one stage spur gear transmission using a topological approach is tackled.This approach is based on the concepts of topological collections and transformations and implemented using the MGS（modeling of general systems）language.The topological collections are used to specify the interconnection laws of the one stage spur gear transmission and the transformations are used to specify the local behavior laws of its different components.In order to validate this approach,simulation results are presented and compared with those obtained with MODELICA language using Dymola solver.Since good results are achieved,this approach might be used as a basis of unification for the modeling of mechatronic systems.     

A Time Frequency-Based Approach for Defect Detection in Composites Using Nonstationary Thermal Wave Imaging

Russian Journal of Nondestructive Testing - Characterization of various industrial components without impairing their future utility increases the necessity of nondestructive testing (NDT)...     

A new boundary finite element method for fluid–structure interaction problems

In order to study problems on fluid–structure interaction, we have used a mixed formulation which couples the classical functional of the structure with a new variational formulation by integral equations for the fluid. This formulation has the advantage over the finite element methods of avoiding the discretization of the fluid domain. Furthermore, unlike collocation methods, the explicit calculation of the Hadamard finite part of the singular integrals is avoided. This leads after discretization by boundary finite elements to a small and symmetrical algebraic system. Typical examples are presented that demonstrate the efficiency of this variational formulation by studying the sound transmission through a baffled plane structure and through a flexible panel backed by a rigid cavity. These include the calculation of the transmission loss factor and the determination of which modes dominate the noise transmission. Good agreement is obtained between numerical results and analytical results found in the literature.     

Anodic behaviour of copper electrodes containing arsenic or antimony as impurities

The anodic behaviour of three different copper electrodes in sulphuric acid medium was investigated using cyclic voltammetry in the potential range between the rest potentialE _i=0=–0.34 V and +0.80 V vs the Hg, Hg₂SO₄/K₂SO₄ saturated (MSE) reference electrode. Arsenic dissolved in the electrode matrix as well as oxygen dissolved in solution were found to delay passivation. The anodic peak current density was proportional to the square root of the potential sweep rate in two consecutive domains. An unusual break was observed for high scan rates (>50 m V s^–1) and was attributed to an increase of the medium viscosity because of the large gradient of concentration near the electrode surface. On the other hand, current oscillations, usually observed in the anodic processes of metallic electrodes, have been studied as a function of the electrode vertical/horizontal positions. Gravity has been found to affect both the frequency and the amplitude of the oscillations. X-ray diffraction measurements conducted on galvanostatically electrolyzed samples revealed, besides copper metal, the presence of copper sulfate pentahydrate and trihydrate for Cu–As and Cu–Sb, respectively. SEM analysis showed the existence of preferential domains of white product on a darker background of metallic copper or copper oxides.     

Miniaturized fractal rat-race, branch-line, and coupled-line hybrids

In this paper, space-filling curves have been used to realize a family of miniaturized hybrids. The large surface area occupied by a conventional structure has been significantly reduced through the use of space-filling curves having the same electrical characteristics. Several space-filling curves have been studied and implemented in different designs. The second-iteration Moore rat-race coupler occupies only 12.6% of the conventional coupler's area, while the area of the second-iteration Sierpinski branch-line coupler is 24.7% of the conventional case. On the other hand, a nine-section Minkowski coupled-line balun is confined in 60% of the conventional balun's area. However, the effective size reduction depends on the used space-filling curve, compression ratio, and associated coupling between segments. The performance of the proposed space-filling hybrids is as good as that of the corresponding conventional structures, and even better in some cases. The design and simulation of the proposed space-filling hybrids have been performed using a moment-method-based full-wave electromagnetic simulator. Measurements of one fabricated coupler prototype are in good agreement with simulation results.     

An empirical evaluation of three regional growth models

There exist a variety of models pertaining to the explanation of the regional growth process. Some empirical evidence exists in support of some of these models. It is not possible, however, to evaluate the relative merits of the models on the basis of the evidence, for the data base used for each differ from that used for the others. Yet, in view of the large number of models available, and the tendency to develop new ones, it is crucial that such an empirical evaluation be made.In this paper we consider the three most widely accepted demand models of regional growth, and examine the ability of each to explain the variation of growth experience among the different regions of the U.S. We also examine the degree to which the empirical evidence support or contradict the implicit assumptions and implications of each.Because a common data base is used for the estimation of all three models (cross-section samples on the 48 contiguous states and the District of Columbia, 1947, 1958 and 1963), we are able to assess the relative merits of the models and their dynamic behavior.The results reported in this study are based on those of a research project on regional growth sponsored jointly by the Japan-American Institute of Management Science, Hawaii and Fujitsu Ltd., Japan. Mr. M. Akiyama and M. J. Fujiwara of Fujitsu Ltd., collaborated with the author in that project. Their contribution as well as the support of JAIMS and Fujitsu are gratefully acknowledged. The views expressed in this paper, however, are solely the author's.     

Electrodissolution de la millérite en milieu chlorhydrique

Résumé L'électrodissolution deMS synthétisé a été étudiée en milieu d'acide chlorhydrique à 25° C. L'influence de la concentration des ions d'hydrogène (pH 0.46–2.68), de nickel (0–1 M) et de chlore (1–4 M) a été examinée. Les études potentiocinétiques et potentiostatiques ainsi que les diagrammesE-pH de NiS-H₂O ont clarifié la cinétique électrochimique et le mécanisme de dissolution deNiS. La surface attaquée et les produits de corrosion ont été examiné par rayons-X, microscopie électronique à balayage, dispersion des rayons-X et absorption atomique.

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The electrodissolution of syntheticMS has been studied in hydrochloric acid at 25° C. The influence of hydrogen ions (pH 0.46–2.68), nickel ions (0–1 M) and chloride ions (1–4 M) has been examined. Potentiokinetic and potentiostatic studies and alsoE-pH diagrams of NiS-H₂O clarified the electrochemical kinetics and mechanism of the dissolution ofNiS. The attacked surface and dissolution products were examined by X-rays, scanning electron microscopy, X-ray dispersion and atomic absorption.

     

Electrodissolution of synthetic covellite in hydrochloric acid

A systematic study has been undertaken to investigate the anodic dissolution characteristics of impure commercial and synthetic covellite. It has been observed that the dissolution is strongly influenced by the pH and chloride concentration and also shows a typical active-passive type of behaviour with production of elemental sulphur. The rate of the dissolution process is accelerated by the formation of a CuCl ₂ ^– complex at high chloride concentrations whereas at lower concentrations of hydrochloric acid the electrochemical oxidation to sulphate is predominant.On leave at the Université du Québec à Chicoutimi (1979).     

Concentration effects of hydrochloric acid on the anodic behaviour of lead sulphide

The anodic dissolution of lead sulphide is studied at various chloride concentrations and at different pH values. At 25° C it is found that in hydrochloric acid the dissolution rate reaches a maximum around 3.0 mol dm^–3. It has also been observed that at concentrations between 0.7 and 1.2 mol dm^–3, a crystalline sulphur deposit formed during the dissolution process leads to an independent peak on theI-E curve whereas at higher concentrations it merges with the PbCl₂ peak formation. pH has no significant effect on the dissolution rate. The results of a systematic study on the kinetics of the dissolution process as a function of concentration, temperature and pH are discussed.