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)     

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.     

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.     

The elastic field around an elliptical crack in an anisotropic medium under an applied stress of polynomial forms

A general form is presented for the stress disturbance caused by an elliptical crack in an anisotropic medium under an arbitrary stress field in the form of polynomials. Somigliana's dislocation method is employed for analysis as Willis [4] did, but a different integral process is taken. The results are expressed in the integral forms defined on the subspace of the surface of a unit sphere. The following theorem is proved: If the displacement discontinuity of the elliptical Somigliana's dislocation has the form where is a homogeneous polynomial of degree $\text{N}$ in the coordinates $\text{x′}{}_1$ and $\text{x′}{}_2$ and $\text{a}{}_1$ and $\text{a}{}_2$ are the semi-axes of the elliptical Somigliana's dislocation, the stresses on the plane of the Somigliana's dislocation are inhomogeneous polynomials in the coordinates, whose terms are of degree $\text{N, (N ? 2}$), $\text{(N ? 4),4.}$     

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.     

Failure Analysis of an Effluent Treatment Plant in an Oral Care Industry

Reports of environmental pollution by industries worldwide call for an urgent need to assess wastewater treatment facilities in various industries. This study presents an assessment of a wastewater treatment plant in an oral care (toothpaste) industry. The industry was visited, facilities for wastewater treatment were assessed (based only on efficacy to remove selected environmental and human’s health-related pollutants) and measurement of essential design parameters and facility characteristics were conducted. The study revealed that the averages of flow rate, biochemical oxygen demand at 5 days (BOD₅), chemical oxygen demand (COD), suspended solids (SS), iron concentration, and total solids (TS) in the influent wastewater into the plant were 4.96 ± 0.6 m³/d; 90 ± 5 mg/L; 224 ± 8 mg/L; 1266.78 ± 10.24 mg/L; 0.31 ± 0.11 mg/L, and 2198.65 ± 20.44 mg/L, respectively. Individual efficacies were as follows: 0.49, 0.28, and 0.38% for SS, TS, and calcium, respectively. The overall efficacy of the wastewater treatment facility was found to be 0.020% which was significantly lower than expected. This indicates that no treatment was conducted on the wastewater and that the wastewater is being discharged into the environment essentially untreated. Equalization time (t _eq) was found to be 2.0 h with equivalent equalized BOD₅ concentration of 90 ± 5 mg/L, while expected volume for the equalization tank is 1.5 m³. It was concluded that failure (lower overall efficacy) of the system can be attributed to lack of an equalization tank, inadequate treatment processes, and refusal to apply standardized engineering code and practices. Although such conditions are rare in developed nations, these results demonstrate the problems in pollution control in developing communities.     

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.     

E-Modul-Messungen an amorphen Legierungen

Determination of Young's Modulus in Amorphous Alloys In this paper metal-metal glasses like Zr_100?xM_x, (M = Fe, Co, Ni) and metal-metalloid glasses like (Fe_100?xM_x)₈₃B₁₇ have been investigated. The change in Young's modulus with composition is determined from measurements of the density and the sound velocity. The obtained results and the accuracy of the determination are compared with those of other authors. The results can be interpreted in terms of short range order, misfit and electrons per atom ratio.     

Weighting-function construction for an elliptical normal-detachment crack in an unbounded body

Weighing-function expressions are given for an elliptic normal-detachment crack in an infinite body, which have been used to calculate K₁ for uniform and linear load distributions in the range in (ratio of the minor and major axes of the ellipse) from 0.2 to 1. These K₁ are compared with theoretical values to judge the accuracy of the weighing functions. Good accuracy (about 6%) is provided by the weighing functions constructed with elliptic coordinates and on the bases of the Oore- Burns general treatment in combination with Rice's formula, apart from points on the major axis. An integral condition is derived for the weighing function, and this is used in refinement of the unknown weighing function.Translated from Problemy Prochnosti, No. 5, pp. 60–69, May, 1993.     

On an inversion formula

This paper introduces a Kontorovich-Lebedev type of integral transform which is adapted to the truncated infinite interval a ? r < ∞. The radiation condition is applied at infinity and a complex boundary condition is applied at r = a. The inversion formula developed for this transform involves only convergent series and integrals.     

Load-carrying capacity of an anisotropic plate with an arbitrarily oriented crack

The problem of the critical equilibrium of a brittle anisotropic plate with an arbitrarily oriented crack subjected to biaxial tension-compression is analyzed. The anisotropy of the resistance to brittle fracture is defined by an expression for the cohesion modulus . It is assumed that crack propagation takes place along a plane for which the normal tensile stresses reach the critical level earlier than those for any other plane, and solutions for stresses in the vicinity of a crack tip are used [1].     

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.     

Elastic-plastic analysis of an arbitrarily-oriented mode III crack touching an interface

In this paper we investigate a semi-infinite crack terminating at an arbitrarily oriented interface between two elastic-plastic materials under an anti-plane shear loading. An analytical solution is first developed for general power-law hardening materials under a mode III loading. If both materials have the same hardening exponent, the formulation results in a nonlinear eigenequation which can be solved numerically. The stress singularities are determined as a function of two material constants: the hardening exponent n and parameter G which represents the relative resistance of the two materials. In addition to the power of the singularity, the stress, strain and displacement asymptotic fields are also determined. If the hardening exponents are not the same, the leading order terms of an expansion model ensure the stress continuity across the interface. The results show that the stress singularity mainly depends upon the material having the larger hardening exponent, with the highest stresses in the material having the smaller hardening exponent. By taking the hardening exponent n , the perfectly plastic bimaterial problem is studied. It has been found that if the crack lies in the less stiff material, the entirely plastic asymptotic fields around the crack tip can be determined. On the other hand, if the crack lies in the stiffer material, the crack-tip fields are partially elastic and partially plastic. For both cases, unique asymptotic fields can be determined explicitly. For those cases when the materials present a strain hardening property, different mathematical models are established.     

Schallemissionsmessungen an beschichteten Stahlblechen

Acoustic Emission Measurements of Coated Sheet Steel Acoustic emission measurements of differently coated steel sheets have shown that the damaging behaviour of this group of materials can be investigated with the aid of this procedure. With electroplated sheets, the acoustic emission at the same basical material depends on:

• (a) the deposit metal
• (b) the composition of the electrolytes
• (c) the deposite current density
• (d) the thickness of the electrodeposit.

Investigations carried out on phosphatized and/or painted steel sheets have shown a dependently of the acoustic emission on:

• (a) the kind of phosphatization
• (b) the chemical composition of the paint
• (c) the level of the stoving temperature
• (d) the weathering
• (e) the thickness of the paint.

On the hitherto investigations the acoustic emission was registered only as impuls rate. In order to obtain more aimed statements on the failure of adhesions and on the formations of micro-cracks, and in order to elucidate the mechanisms of adhesion and failure of adhesions, the analysis of the amplitudes and frequencies of the acoustic emission of coated metals was started.     

Problems of Heat Conduction for an Angular Region with an Internal Source

Exact solutions of nonstationary problems of heat conduction have been obtained for an unbounded rectangular region when the opening angle is equal to /(2n + 1), where n is any natural number. By passage to the limit it has been shown that no stationary regime is possible for the rectangular region in the case of action of a constant internal source. The exact solution of the stationary problem for an angular region with an arbitrary opening angle ₀ has been given. It has been proved that in the presence of a constant heat source the stationary regime is possible just for the acute angle ₀ /2, while for the right or obtuse angles ₀ /2 the stationary regime is impossible, since the temperature increases without bound at internal points.     

Stress singularities in composite materials with an arbitrarily oriented crack meeting an interface

The plane, bending and antiplane strain elastostatic problems for two bonded half planes containing an arbitrarily oriented semi-infinite crack meeting the interface, are examined. A simple analogy between the interfacial continuity conditions for the plane and bending problems is derived and its implications are discussed. Using the eigenfunction-expansion method the crack tip stress singularities for various crack orientations and material combinations are compared for the three problems. It is shown that, under certain conditions, singularities are no longer present in the stress field. In the case of the antiplane strain problem subsequent paths of crack propagation are predicted.

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Résumé On examine des problèmes élasto-statiques en déformation plane, de flexion, et antiplanaire rencontrés dans deux demi-plans solidaires comportant, dans leur interface, une fissure semi-infinie orientée arbitrairement. On tire une analogie simple entre les conditions de continuité et interfaciales qui se présentent dans le cas des problèmes plans et flexionnels; ses implications sont discutées. En utilisant une méthode d'expansion d'une eigenfonction, on peut comparer les singularités de contraintes aux extrémités de la fissure, pour diverses orientations de la fissure et de combinaisons de matériaux différents. On montre que, sous certaines conditions, le champ de contraintes peut ne plus présenter de singularités. On peut par ailleurs prédire les chemins de la propagation d'une fissure dans le cas d'une déformation antiplanaire.

     

Investigation of the instability of an arc descharge in an air flow

Using an automated complex of spectral apparatuses that allow one to determine local profiles of averaged temperature and its oscillations in a dc arc-discharge column, we investigated the temperature instability of the arc plasma in a laminar air flow. We show that the character of oscillations corresponds to the model of thermal destabilization of discharge. Academic Scientific Complex “A. V. Luikov Heat and Mass Transfer Institute of the Academy of Sciences of Belarus,” Minsk, Institute of Molecular and Atomic Physics of the Academy of Sciences of Belarus, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 69, No. 5, pp. 800–804, September–October, 1996.     

Application of an energy balance and an energy method to dynamic crack propagation

The speeds of fast running cracks in a range of quasi-brittle materials are measured as a function of the dynamic strain energy release rate. From the results, the heat output associated with the plastic work at the crack tip is calculated as a function of crack speed using an energy balance, and compared with the heat outputs determined experimentally using an energy method. A generally good agreement is found between the calculated and the experimentally measured variation of heat output with crack speed.

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Zusammenfassung Die Geschwindigkeiten schnell-laufender Brüche werden als Funktion der dynamischen Energiefreisetzungsrate für eine Anzahl unterschiedlich spröder Materialien gemessen. Aus diesen Ergebnissen wird mit Hilfe einer Energiebilanz die durch die plastischen Deformationen an der Rißspitze entstehende Wärme berechnet und mit der durch eine Energiemethode experimentell gemessenen Wärme verglichen. Es wird eine im allgemeinen gute Übereinstimmung zwischen dem berechneten und gemessenen Verlauf der Wärme als Funktion der Bruchgeschwindigkeit gefunden.

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Résumé Les vitesses de propagation des fissures en développement rapide dans une gamme de matériaux quasi-fragile sont mesurés en fonction de la vitesse de relaxation de l'énergie de déformation dynamique. A partir des résultats obtenus, on calcule la dissipation de chaleur associée au travail de formation plastique à l'extrémité de la fissure en fonction de la vitesse de la fissure correspondant à un équilibre énergétique. On compare ces valeurs calculées avec les dissipations de chaleur déterminées expérimentalement à l'aide d'une méthode énergétique. En général, on trouve un bon accord entre les variations de dissipation de chaleur calculées et mesurées par voie expérimentale en fonction de la vitesse de fissuration.

     

Two-dimensional scattering from an impenetrable cylindrical obstacle in an acoustic quarterspace

The problem of sound scattering by an infinitely long hard or soft circular cylindrical obstacle suspended near a rigid corner is investigated. The separation of variables technique, the appropriate wave field expansions and the method of images along with the translational addition theorem for cylindrical wave functions are used to derive a closed-form analytical solution in form of infinite series. The analytical results are illustrated with a numerical example in which the cylindrical obstacle is positioned near the rigid boundary of a water-filled acoustic quarter-space. The backscattering form function amplitude and spatial distribution of the total acoustic pressure are evaluated and discussed for representative values of the parameters characterizing the system. The effects of incident wave frequency, angle of incidence and proximity of the cylinder to the rigid boundary are examined. Limiting case involving an infinite cylinder in an acoustic halfspace is considered and fair agreement with a well-known solution is established.     

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.