Autocompensation of an ion beam in an accelerator with an anode sheath

Experiments to study the autocompensation of an ion beam are described. It is shown that in accelerators with an anode sheath and isolated collector, autocompensation occurs as a result of the excitation of an auxiliary non-self-sustained gas discharge. Pis’ma Zh. Tekh. Fiz. 23, 69–73 (May 26, 1997)     

Plane problem for an anisotropic body containing an inclusion surrounded with an elastic layer

We construct an algorithm for the solution of the plane problem of the theory of elasticity for a three-component composition in which the boundary between the matrix and inclusion is regarded as an elastic layer. We give a quantitative estimate of the dependence of the generalized stress concentration (intensity) factors near the tip of a curvilinear notch and a perfectly rigid inclusion on the loading mode, elastic characteristics, the width of the indicated elastic layer, and the (small) radius of curvature at the tip of the concentrator. Translated from Fizyko-Khimichna Mekhanika Materialiv. Vol. 36, No. 3. pp. 27–34. May-June, 2000.     

Polarisationsoptische Spannungsuntersuchungen an unsymmetrischen Stabecken und an Doppelhaken

Zusammenfassung Im ersten Teil der vorliegenden Untersuchung werden die Spannungsverh?ltnisse in den Krümmungen von unsymmetrischen, auf Biegung beanspruchten Stabecken experimentell untersucht. Zur rechnerischen Ermittlung der Spannungserh?hung wird eine für viele praktisch vorkommende F?lle brauchbare empirische Formel angegeben, die durch zahlreiche Versuchsergebnisse gestützt wird. Diese Formel kann auch für andre Profile und Belastungsf?lle, die sich auf den einfachen Fall des Stabecks zurückführen lassen, angewendet werden. Ferner werden für zahlreiche F?lle von Einzel- und Momentbelastung die experimentell ermittelten Netze der Isoklinen und Hauptspannungstrajektorien mitgeteilt; letztere sind besonders für die Anordnung von Verst?rkungseisen beim Eisenbetonbau wichtig. Im zweiten Teil wird eine spannungsoptische Untersuchung des Doppelhakens durchgeführt. Ein Vergleich der experimentell gefundenen Spannungen mit dem Wert, der sich aus den für stark gekrümmte Tr?ger geltenden Beziehungen ergibt, zeigt, da? beide ausgezeichnet übereinstimmen. Diese Arbeit schlie?t sich an eine Reihe von Untersuchungen an, die im Mechanisch-technischen Laboratorium der Techn. Hochschule München an der polarisationsoptischen Versuchseinrichtung durchgeführt wurden. — Ich fühle mich verpflichtet, meinem hochverehrten Lehrer, Herrn Prof. Dr.L. F?ppl, für sein gro?es Entgegenkommen und für seine Anregungen meinen ergebensten Dank zum Ausdruck zu bringen.     

Kinking of an interface crack in an orthotropic bimaterial

We investigated the asymptotic problem of a kinked interface crack in an orthotropic bimaterial under in‐plane loading conditions. The stress intensity factors at the tip of the kinked interface crack are described in terms of the stress intensity factors of the interface crack prior to the kink combined with a dimensionless matrix function. Using a modified Stroh formalism and an orthotropy rescaling technique, the matrix function was obtained from the solutions of the corresponding problem in transformed bimaterial. The effects of orthotropic and bimaterial parameters on the matrix function were examined. A reduction in the number of dependent material parameters on the matrix function was made using the modified Stroh formalism. Moreover, the explicit dependence of one orthotropic parameter on the matrix function was determined using an orthotropic rescaling technique. The effects of the other material parameters on the matrix function were numerically examined. The energy release rate was obtained for a kinked interface crack in an orthotropic bimaterial.     

Study of an electrical model of an ecological system

An analysis is made of an electrical model of an ecological system. The model is a physical object which can be tested and which has a finite number of external pole points. The methods, characteristics, and possibilities of modeling informative parameters on pollution are examined. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 20–25, May, 1999.     

Axi-symmetric loads on an elastic half-space containing an inclusion

The problem of a linearly elastic half-space containing a rigid-lubricated cylindrical inclusion and subjected to a normal static circular line load at the plane surface is treated. The stress and displacement components on the plane boundary yield simple expressions from which quantitative results are readily determined. The singularities existing under the applied load are examined.     

Velocity of an electric arc in an annular gap

We investigate the influence of the current, magnetic-field induction, air flow, and interelectrode gap on the arc velocity in an annular gap between concentric electrodes. Generalized equations in critical (dimensionless) form are presented for the experimental data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 19, No. 6, pp. 1046–1051, December, 1970.     

A point force and an edge dislocation in an elliptical inclusion embedded in an infinite medium

The plane elasticity problem of an infinite plate containing an elliptical inclusion is considered and the solutions for a point force and/or a dislocation located inside the inclusion are derived. By using the complex potential approach of Muskhelishvili, the general solutions are obtained in a form of a certain function flus an infinite series. The numerical convergence of the solutions is found to be tter than that of Warren's solutions for the same problem. The proposed solutions are also appropriate for the case of a point force and dislocation acting at a point just on the interface.     

Annular punch on an elastic layer overlying an elastic foundation

The problem solved here is the axisymmetric mixed boundary value problem of the isotropic homogeneous theory of elasticity, in which the normal displacement is specified inside an annular area $\text{a ≤ r ≤ b}$, the normal stress is zero in $\text{r < a, r \# b}$ and the shearing stress is zero on the whole face $\text{z = ?h}$, the upper face of the elastic layer; the continuity of the normal and radial displacements and the normal and shearing stresses is assumed at the interface $\text{z = 0}$ between the elastic layer and the elastic foundation having different elastic constants. The problem is reduced to the solution of a Fredholm integral equation of the first kind. The Fredholm integral equation is further put in terms of four simultaneous Fredholm integral equations of the second kind in four unknown functions. The iterative solution of these integral equations has been obtained for $\text{epsi = b/h ? 1}$, and $\text{λ = a/b ? 1}$ for the case of an annular cylindrical punch. The expressions for the normal stress $\text{σ}{}_{\mathrm{zz}}\text{(r, ?h)}$ for $\text{a ≤ r ≤ b}$ and the total load $\text{P}$ on the punch have been obtained.     

使用光纤放大器的频分复用光纤传输系统

报道了一个使用光纤放大器的两路非相干频分复用光纤传输实验系统。系统采用国产ＤＦＢ激光器作光源，用意大利生产的光纤放大器作在线放大器，用自制的光学谐振腔作光学滤波器和解复用器，采用ＦＳＫ调制制式，将１４０Ｍｂ／ｓ非归零伪随机码传输了５０公里，得到了很好的眼图。在频道间距为１０ＧＨｚ情况下，未观测到邻道干扰和光纤放大器的非线性现象。     

Thermal protection of an area from an incident gas jet

Results are offered from an experimental study of the decrease in thermal effect of a jet upon a normally oriented surface produced by introduction of cold air or water into the central portion of the jet.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 62, No. 4, pp. 555–558, April, 1992.     

Electroless silver as an optical coating in an operational environment

Long-term, independent experiments show a high degradation rate and short lifetime for electroless silver as a mirror coating operating at visible wavelengths in an observatory environment. Acid formed by water vapor mixing with sulfur in volcanic dust diffuses through pinholes in the coating generated during deposition. This causes internal corrosion and delamination after only 3-4 months. In addition, a layer of silver sulfide results in tarnish, which reduces reflectance. Rates of sulfidation and internal corrosion are shown to depend on the concentration of sulfur and the exposure rate. Comparisons of performance, lifetime, and the application process are made with bare aluminum and two variations of enhanced silver.     

Thermoelastic analysis for an opening crack in an orthotropic material

The thermoelastic analysis of an opening crack embedded in an orthotropic material is made under applied uniform heat flux and mechanical loadings. To simulate the case of an opening crack filled with a medium, a thermal-medium crack model is proposed. The thermally permeable and impermeable cracks are the limiting ones of the proposed thermal-medium one. The crack-tip thermoelastic fields induced by a crack in an orthotropic material are determined in closed forms. The elastic T-stress can be also obtained explicitly. The effects of applied mechanical loadings and the thermal conductivity of crack interior on the heat flux at the crack surfaces and the mode-II stress intensity factor are investigated through numerical computations. The obtained results reveal that an increase of the thermal conductivity of crack interior decreases the mode-II stress intensity factor. And when an applied mechanical loading is increasing, the mode-II stress intensity factor is rising.