Electrical contact resistance between two metal surfaces in contact under a load is related to the real contact area and the number of contact points. The real contact area is usally much smaller than the apparent contact area, because the actual metal surface has many fine asperities on it. The measured value of electrical contact resistance does not agree well with the theoretical value obtained by neglecting asperities on the metal surfaces. The reason is that the metal sur-faces are not perfectly flat and fine asperities on them make the mutual contact. The contact between asperities is related to distribution of asperities, in other words, to the number of asperi-ties per unit area and the height difference of asperity-tips. Therefore, it is presumedd that the contact resistance depends on the surface roughness and the shape of contact metals. The author has experimentally confirmed the distribution of the height of asperity-tips and dependence of the contact resistance upon the surface roughness and the shape of contact metals.
Report (I) described the experimental results of dependence of the electrical contact resistance upon the surface roughness and the size of contact metal. This report theoretically describes the above relation. The mean height difference between the asperity-tips is obtained by the statistical theory. From the result, it was made clear that the mean height difference between the asperity-tips depended on the surface roughness and the apparent contact area. The apparent contact area is proportional to the surface roughness and the radius of sphere or cylinder of contacts, and the contact resistance is a function of the mean height difference between the asperity-tips. Therefore, the contact resistance depends upon the two factors mentioned above. The author obtained the equations to calculate the electrical contact resistance as a function of the above factors and the load of contacts. The results of calculation agreed well with the ex-perimental results.
The optical absorption bands in visible region which are produced in γ-ray-irradiated PMMA and copolymers of MMA-AN are bleached with a sharp boundary line in oxygen atmosphere below the glass transition temperature. By investigating the penetration rate of this boundary line, it is proved that this phenomenon is caused by oxygen molecules adsorbed on the plastic surface penetrated according to Fick's diffusion law and reacted with “chromophores”. Adsorption of oxygen molecules on irradiated plastic surface needs the activation energy of about 9.38 Kcal/mole. Therefore, it takes an induction period before the appearance of the boundary line. This induction period is independent of the composition of plastics and dosage, but depends on the gas pressure of oxygen and temperature. G-values for the production of chromophores are estimated by applying the diffusion law to the penetration rate of the boundary line. These values vary between 0.1 and 1.5 according to the composition of plastics. They coincide very well with the concentration of radical measured by the DPPH method and also with the G-values for the production of trapped radical measured by the use of ESR by many investigators.
As the electrical contact resistance of silver is usually very small and the contact maintains a good condition, silver contact is widely used. Silver is scarcely oxidized in ordinary atmosphere, but easily sulphurized in the atmosphere containing sulphide gas whereby the contact resistance be. comes very large. In good atmosphere containing no sulphide gas the contact resistance does not increase greatly. In an experiment, howerver, many contact pieces failed in ordinary atmos-phere when they were used for impulse relay. The cause of poor contact did not seem to be the sulphurized layer because the other similar contacts in the same room were not sulphurized. Investigation on the cause of poor contact was made by several methods. It is now clear that the cause is the sticking of dust, especially SiO2 on the contacts SiO2 gives rise to a non-conductive layer by the heat of discharge.
In order to represent the characteristics of optical systems in their respective aberrational re-gions, the “Intrinsic coefficients” are defined as the aberration coefficients (1) which are necessary and sufficient to describe all geometrical-opitical imaging properties and (2) which are of the values in the case when the entrance pupil is placed at the first principal plane. To correspond with the concept of focal length in the Gaussian region, intrinsic coefficients for objects at infinity are called simply the intrinsic coefficients. These coefficients relate with the apparent aberration coefficients, which show the working aberration in the case when the optical system is used as a component of a composite system, by a linear transformation. The matrix of this transformation is called the “Characteristic matrix” of the composite system, since it describes the whole constructional charac-teristics of the composite system concerning the aberration. The present paper applies these new treatment of optical systems by both intrinsic coefficient and characteristic matrix to the first order chromatic aberration and gives explicit formulas of the above matrix. Next, the theory is applied to the varifocal lens systems to derive various important results for the characteristic matrix of these system. Lastly, the author illustrates that the numerical value of intrinsic coefficient of every component is decided when certain conditions are imposed upon the stable aberration correction of the total system during the zooming as if the focal length of every component is decided for the aimed zoom ratio.
Concerning the author's newly proposed treatment of aberrational region of optical systems with the use of intrinsic coefficients and characteristic matrix, when it comes to extending the case to fifth order region in analyzing and synthesizing the optical system, the degree of freedom of the system in the said region should be first acquainted with. Exact analytical formulas are shown which express the fifth order intrinsic coeffients of thin lens contact system in air in terms of constructional data of the system. Various new results derived from these formulas are discussed. Some of them are as follows. 1. The degree of freedom is regarded as six. 2. In exchanging object for image or viceversa, there are no simple relations between fifth order intrinsic coeffients before and after the exchange. 3. Sagittal curvature is saturated by the fifth order term.
Nuclear magnetic resonance absorption of stretched polymers is studied. Second moment for stretched polymers is given by ‹ΔH2›=S0-S2 sin2ω+S4 sin4ω where S0, S2, S4 are parameters which are calculated from molecular structures, and ω is the angle between the stretched direction of the polymer and external magnetic field. By assuming appropriate models, S0, S2, S4 for polyethylene (Marlex 50), polyvinyl alcohol and Teflon are calculated respectively, and calculated second moments for those three polymers are compared with observed values. Agreement was best in Teflon. The interproton distance in methylene group of polyvinyl alcohol was preferred to be 1.72Å rather than 1.79 Å at -150°C.
In a previous paper of this series, it was shown that there is a possibility of chemical reac-tions taking place between phenol reisn and polyvinyl butyral molecules during curing process of their mixture, the possibility being deduced from the occuring of a new loss peak (called a2-dispersionn or α2-peak in the previous and this papers) at about 160°C. In the present paper the mechanism of reaction between phenol resin and polyvinyl butyral is, systematically investigated by means of the vibrating reed method using model materials which are-derivatives of polyvinyl butyral differing only in side groups. So far as the structure of polyvinyl butyral molecule is concerned, the occurring of α2-peak of the mixed system is related to the existance of hydroxyl group, but not acetyl or butyral group, on the molecule. This is supported by the results obtained on a few types of polyvinyl butyral. resins found on the market. Therefore, the effect of hydroxyl groups of polyvinyl butyral molecule mixed with phenol resin on the occuring of the α2-peak may be explained as follows: When a. mixture consisting of phenol resin (A-Stage) and polyvinyl butyral is heated at a high temperature, some graft or cross-linked structure will be produced by co-condensation reaction between hydroxyl groups on polyvinyl butyral and methylol or amino groups on phenol resin molecules during the course of curing reaction. This hypothesis is supported by the fact that above 170°C the dynamic elastic storage modulus of a specimen of polyvinyl butyral mixed with phenol resin, in contrasted with the case of derivatives of polyvinyl butyral lacking in hydroxyl group on the molecule, in-creases again with the rise of measuring temperature except when the content of phenol resin in the mixed system is high.
An apparatus for measuring secondary electron energy distribution by a longitudinal magnetic field has been devised. It can also measure the energy distribution of electrons or other charged particles emanating within a small solid angle from their source. Equations used in designing and dimensions of the complete set are given. The energy resolution is 10%. The main body of the analyzer is of brass. The magnetic field is provided by a pair of Helmholtz coils, 100cm in diameter each, the axes of which are made to coinicide with the direction of the earth's field. The method of preventing the interior of the analyzer from becoming contaminated with oil vapor from oil diffusion pumy is explained. Performance of the anaylzer is studied by placing an indirectly heated tantalum sleeve outside the first slit and applying a voltage between the sleeve and analyzer slit. Response of the analyzer to electrons originating at several fixed energies is measured as a function of magnetic field. The energy distribution of secondary electrons from tantalum with the primary voltage of 100 V is given as an example.
A piece of porous nickel, 20_??_40% in porosity, is impregnated with Ba(OH)2 in hydrogen atmosphere, the impregnation extending to 65_??_75°0 of the pores. This being used as a cathode, work function of 2.2 eV and current density of 0.05 A/cm2 or more were obtained. Though the time required for evacuation was 3_??_4 times more than that in the case of sprayed oxide coated cathode, stability against ionic and electronic bombardments was far better. By the control of the grain size of nickel powder, molding pressure and sintering temperature, the cathode can be made to suit to various purposes. The emission obtained was rather small, but its increase is expected by the addition of proper reducing agent.
Diameter of contact circle and deformation of plastic surface neighbouring the contact region between a glass hemisphere and a flat plate of plastic are measured by observing Newton's rings. The cube of diameter of contact circle is proportional to the load and radius of curvature. It is, therefore, verified that Hertz's equation for elastic contact is applicable to plastics. However, in a wide range of time of loading, it is indicated that Young's modulus in Hertz's equation is also dependent upon the load as well as the time of loading. It is found that a wave-like deformation takes place on the surface of plastics neighbouring contact region. The surface deformation extends to a considerable large distance from contact region as compared with the radius of contact circle. It seems that the size of surface deformation increases with load W in proportional to W2/3. An application of tangential force increases the size of surface deformation on one side of contact region and decreases on the other side. When the applied tangential force is 80_??_90 percent of the maximum static friction, the height from the position of contact circle to the deformed surface of plastic reaches one-half of or over the amount of contact depth. In applying the tangential force smaller than the maximum static friction, it is observed that the abrupt slip does not occur, but a very slow slip occurs.