Showing papers by "Helsinki University of Technology published in 1974"
TL;DR: In this article, the relative integrated intensities of different orders of reflections were calculated and calculated values of extinction distances were used to estimate the image width of a dislocation whose Burgers vector could be determined.
Abstract: Synchrotron radiation which is emitted into a narrow cone and which has a continuous spectrum was succesfully used in X-ray topography. The exposure time to take a set of topographs (a transmission Laue pattern) from a silicon crystal on a fine grain film with a geometric resolution of a few microns turned out to be as short as some seconds. As an example for the use of the new method the contrast formation of a defect in the Laue pattern of topographs was analysed in detail. For this purpose the relative integrated intensities of different orders of reflections were calculated. They and the calculated values of extinction distances were used to estimate the image width of a dislocation whose Burgers vector could be determined.
Synchrotronstrahlung, die ein kontinuierliches Spektrum besitzt und in eine schmale Keule emittiert wird, wurde erfolgreich in der Rontgentopographie benutzt. Es erwies sich, das die Belichtungszeit, um mehrere Topographen (ein Laue-Bild mit Transmissionsverfahren) von einem Silizium-Einkristall auf einen feinkornigen Film mit gutem Auflosungsvermogen aufzunehmen, nur einige Sekunden betragt. Als Beispiel fur die Anwendung der neuen Methode wurde die Kontrastbildung eines Defektes im Laue-Bild der Topographen analysiert. Zu diesem Zweck wurden die relativen integrierten Intensitaten der Reflexe verschiedener Ordnungen berechnet. Diese und die berechneten Werte der Extinktionslangen wurden zur Abschatzung der Bildbreite einer Versetzung, deren Burgers-Vektor bestimmt werden konnte, benutzt.
208 citations
01 Aug 1974
TL;DR: The applicability of the Ludwik, Hollomon, Swift and Voce equations in describing the stress curves of metals was investigated in this paper, where the authors found that the uniform strain values depend on the equation used.
Abstract: The applicability of the Ludwik, Hollomon, Swift and Voce equations in describing the stress - strain curves of metals was investigated. Calculated uniform strain values were found to depend on the equation used. Even when the Hollomon equation gave a high linear correlation coefficient in log-log coordinates, the strain-hardening exponent n could give an erroneous uniform strain. The equation with the lowest standard error of estimate gave the uniform strain nearest to the value obtained by direct measurement from the load-elongation curve.
174 citations
TL;DR: It is shown that an analog associative memory with optimal selectivity can be formed in adaptive processes which use learning algorithms related to the gradient method.
Abstract: It is shown that an analog associative memory with optimal selectivity can be formed in adaptive processes which use learning algorithms related to the gradient method. The information is distributed throughout the memory by a matrix transform.
82 citations
TL;DR: The precordial magnetocardiograms observed are closely related to the conventional 12-lead electrocardiogram, but also reveal new information as compared with the standard ECG.
Abstract: Magnetocardiograms of 24 normal subjects and of 31 patients with cardiac disorders have been studied with the aid of a magnetometer of the gradiometer principle which utilizes a superconducting quantum interference device (SQUID). The precordial magnetocardiograms observed are closely related to the conventional 12-lead electrocardiogram, but also reveal new information as compared with the standard ECG. There are differences between MCGs in different cardiac disorders, but the small number of cases and recording positions applied do not permit analysis of the specifity of the MCG patterns. There are certain differences between 12-lead ECG and precordial MCG in the relative sensitivity to different phases of the cardiac electromotive events. For instance, the magnitude of an S-T segment shift, as measured relative to QRS amplitude, was greater in the MCG. A part of these differences may be explained by a greater proximity effect in magnetocardiography. Magnetocardiography may prove to be of clinical value in cardiac disorders, especially in those producing primary abnormalities in the repolarization process.
54 citations
TL;DR: In this article, the properties of positron surface states in simple metals are discussed in various surface interaction models and numerical estimates for binding energies, annihilation lifetimes and 2γ-angular correlation curves for aluminum are given.
36 citations
TL;DR: In this paper, the viscosity and density of the normal component of liquid in the $A$ and $B$ phases were determined at the melting curve with a vibrating-wire viscometer.
Abstract: The viscosity and the density of the normal component of liquid $^{3}\mathrm{He}$ in the $A$ and $B$ phases have been determined at the melting curve with a vibrating-wire viscometer. The results show that resistive flow of the liquid is accompanied by a flow of zero viscosity. The data thus prove superfluidity both in the $A$ and in the $B$ phase.
30 citations
Proceedings Article•
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TL;DR: The chain antenna as mentioned in this paper is a traveling wave antenna, which consists of a ground plane close to which is a chainshaped conductor along which propagates a TEM wave, and the loops of the chain are rectangular with typical dimensions of 0.4 wavelength times one wavelength.
Abstract: A novel traveling wave antenna, the chain antenna, is described. It consists of a ground plane close to which is a chainshaped conductor along which propagates a TEM wave. The loops of the chain are rectangular with typical dimensions of 0.4 wavelength times one wavelength. Several chain antennas can be connected in parallel giving a grid antenna. The grid antenna has a linearly polarized frequency scannable pencil beam and only one feed point per hundreds of radiating elements which makes it especially suitable for HF, VHF and UHF frequencies when high gain antennas are needed.
17 citations
TL;DR: In this paper, the authors derived state apace models for a basic continuous flow system and proved that a relatively small non-ideality in a real system is sufficient to make it unstable.
Abstract: Basic phenomena of H+and H− ion concentration process are considered, and state apace models are derived for a basic continuous flow system. Inherent non-linearity of the system can he avoided by a change of variables, hut due to the logarithmic measurement via pH the corresponding feedback control system is highly nonlinear. A basic feedback system is proved to be globally asymptotically stable. Through an augmentation of the basic model it is shown that a relatively small non-ideality in a real system is sufficient to make it unstable. On the other hand, a steady state analysis show that the concentration equilibrium is highly sensitive to deviations of parameters related to the controlling chemical reagent, if a concentrated acid or base is being neutralized in a single stage.
17 citations
01 Oct 1974
TL;DR: In this paper, a dual-mode microwave cavity is used to measure fiber orientation in paper, where the modes have equal resonant frequencies and mutually perpendicular electric fields, and the paper is inserted through the cavity so that the electric fields of both modes are in the plane of the paper.
Abstract: A microwave method for the measurement of fiber orientation in paper, is described. The method uses a dual mode microwave cavity where the modes have equal resonant frequencies and mutually perpendicular electric fields. The paper is inserted through the cavity so that the electric fields of both modes are in the plane of the paper. If the orientation of the fibers in the paper is not random the resonant frequencies will differ due to the dielectric anisotropy of the paper. This difference is measured and can be calibrated to give the amount of fiber orientation. Moisture and thickness variations in paper can cause calibration errors. However, if the variations are within certain limits, these errors can be eliminated by a suitable selection of the resonator bandwidths.
16 citations
TL;DR: A review of the nonrelativistic self-consistent symmer-trized orthogonalized plane wave (SCSOPW) method used for determining electronic energy bands in periodic solids is given in this paper.
Abstract: A review of the nonrelativistic self-consistent symmertrized orthogonalized-plane-wave (SCSOPW) method used for determining electronic energy bands in periodic solids is given. Working equations based on the full use of group theory at all stages are presented for elemental crystals. As an example the method is applied to the trigonal selenium crystal.
15 citations
TL;DR: In this paper, a model for dislocation climb is presented which is suitable for treating climb processes such as those expected in dislocation networks, where mass transport is considered to occur by a special pipe diffusion mechanism where the climb force on a dislocation acts as the driving force.
Abstract: A model for dislocation climb is presented which is suitable for treating climb processes such as those expected in dislocation networks. In the model mass transport is considered to occur by a special pipe diffusion mechanism where the climb force on a dislocation acts as the ‘driving force’. It is shown that the climb velocity is proportional to the second derivative of the climb force with respect to the dislocation length. Possible applications of the theoretical model are discussed.
TL;DR: In this article, it was shown that two bicyclic fatty acids present in Finnish tall oil were formed from (5Z, 9Z, 12Z)-5, 9, 12-octadecatrienoic acid, pinolenic acid (I) under the alkaline conditions of sulfate pulping, which formed conjugated isomers which undergo Diels-Alder cyclization during the heating in the tall oil distillation.
Abstract: It was shown that two bicyclic fatty acids present in Finnish tall oil were formed from (5Z, 9Z, 12Z)-5, 9, 12-octadecatrienoic acid, pinolenic acid (I). Under the alkaline conditions of sulfate pulping, pinolenic acid forms conjugated isomers which undergo Diels-Alder cyclization during the heating in the tall oil distillation. The cyclization products, here called cyclopinolenic acids, are bicyclic fatty acids and stereoisomers of 4-(5-pentyl-3a, 4,5,7a-tetrahydro-4-indanyl) butanoic acid (IV and V).
TL;DR: Positron lifetime and X-ray measurements have been performed in a heat-treated 34 Li 2 O65 SiO 2 1P 2 O 5 glass as mentioned in this paper.
TL;DR: Generalized Hermite-Birkhoff interpolation as mentioned in this paper gives a unifying method for constructing exponentially fitted linear multistep methods explicitly, and the construction principle permits study of the convergence and stability properties of these methods.
Abstract: Generalized Hermite-Birkhoff interpolation gives a unifying method for constructing exponentially fitted linear multistep methods explicitly. Fitting may be done at any set of given (real) parameters. The construction principle permits study of the convergence and stability properties of these methods. Moreover, it shows how the properties depend on the corresponding properties of classical linear multistep methods with constant coefficients. The theoretical results are illustrated by some examples.
TL;DR: In this article, the specific heats of rare earth metals Eu and Er have been measured in the temperature range 0.03 to 0.8K, yielding magnetic hyperfine parameters of 13.2 mK, 5.85 mK and 42.3 mK for 151, 153, and 167 Er, respectively.
TL;DR: In this article, an extension of the local inverse theorem of polynomial type operators, recently considered by the same authors in [l-4] for nonlinear systems analysis, is presented.
TL;DR: In this article, it was shown that 3 He has been cooled by adiabatic demagnetization of copper nuclei to 1.6 mK, well into the region of the superfluid phases.
TL;DR: In this article, a microwave instrument for non-destructive testing of the homogeneity of supercalendar rollers used in paper mills is described, which consists of a flat coaxial transmission line a half wavelength long.
Abstract: A microwave instrument for non-destructive testing of the homogeneity of supercalendar rollers used in paper mills is described. The sensor consists of a flat coaxial transmission line a half wavelength long. A sensitivity of more than 0,1% is achieved in measuring small changes in the dielectric constant. Measurement of absolute values of the dielectric constant is also possible.
TL;DR: In this article, a method of numerical calculation is presented which makes it possible to compute the time-dependent behaviour of a number of curved dislocations in a crystal and makes use of certain equations of motion to obtain the dislocation velocities as functions of the elastic forces.
Abstract: A method of numerical calculation is presented which makes it possible to compute the time-dependent behaviour of a number of curved dislocations in a crystal. The technique computes the elastic forces acting on the dislocations and makes use of certain equations of motion to obtain the dislocation velocities as functions of the elastic forces. Simple examples of applications of the method are presented.
TL;DR: In this article, a cryogenic system for studying the properties of He3 between 1 and 15 mK is described, which is used for measurements of viscosity and heat capacity of liquid He3 along the melting curve.
01 Jan 1974
01 Jan 1974
TL;DR: In this article, state space models of an evaporator and washer plants used in pulp and paper industry are set up, and problems of optimal feedforward control are formulated using these models, and computed solutions are presented for the case of an evaporation plant.
Abstract: After a study of an evaporator model with variable liquor volume, state space models of evaporator and washer plants used in pulp and paper industry are set up. Problems of optimal feedforward control are formulated using these models, and computed solutions are presented for the case of an evaporator plant. A practical control method being tested in a washer plant.
Journal Article•
TL;DR: Positron lifetime spectra have been measured in plastically deformed KCl and NaCl single crystals as mentioned in this paper, and the experiments indicate that a third component of the order of 2 nsec is produced by the deformation, and its relative intensity is only weakly dependent on the degree of deformation.
Abstract: Positron lifetime spectra have been measured in plastically deformed KCl and NaCl single crystals. The experiments indicate that a third component of the order of 2 nsec is produced by the deformation, and its relative intensity (2–4%) is only weakly dependent on the degree of deformation.
TL;DR: In this article, a statistical analysis has been made of the data relating to a total of 283 ship casualties in 1971-72; the results are presented and the discussion covers local and seasonal distribution, distribution by other time-dependent variables, and weather, visibility and the use of navigation equipment at the time concerned.
Abstract: The problems associated with marine traffic engineering in the Baltic area are difficult to solve, and casualty statistics are extremely important as a basis for safety and anti-pollution activities. A statistical analysis has been made of the data relating to a total of 283 ship casualties in 1971–72; the results are presented and the discussion covers local and seasonal distribution, distribution by other time-dependent variables, and weather, visibility and the use of navigation equipment at the time concerned. The statistics further cover the type of ship involved, its nationality, loading condition, age, speed, and the damage arising. This paper was presented at the November meeting of a Navigation Group in Helsinki.
TL;DR: A short discussion is given on the programming language ANALITIK available on the Soviet MIR-2 computer designed for description of numerical and analytical mathematical computations.
Abstract: A short discussion is given on the programming language ANALITIK available on the Soviet MIR-2 computer designed for description of numerical and analytical mathematical computations. Some properties and principles of the system are presented. Design objectives and their implementation are reviewed.The programming language ANALITIK available on the MIR-2 computer is a special purpose language designed for numerical and analytical computations. The language and the computer have been developed at the Institute of Cybernetics in Kiev under direction of the well known Soviet cybernetician, academician V. M. Glushkov. It represents a continuation of a product line of special purpose computers for mathematical problems. ANALITIK is a compatible extension of the programming language MIR, which was an Algol-like language but more specifically designed for the solution of numerical problems.
TL;DR: In this paper, the Mg KL 2,3L2,3 radiative Auger threshold is modified by forbidden exciton transitions in MgO and MgF2.
TL;DR: In this article, the smallest obtainable parameter errors (variances) in the interpretation with the least-squares method are discussed, and approximations of the sum of squares contained in the minimum error expressions are obtained using results of numerical integration.
Abstract: The paper discusses the smallest obtainable parameter errors (variances) in the interpretation with the least-squares method. Useful approximations of the sum of squares contained in the minimum error expressions are obtained using results of numerical integration. The approximations lead to especially simple results for long interpretation profiles, when the parameter errors are proportional to the square root of the point separation.
Formulae are developed and examples shown for minimum error calculation in gravimetric interpretation with the cylindrical model and in magnetic interpretation with the two-dimensional plate model. Smallest errors are obtained when the interpretation profile is chosen around the anomaly maximum except for dip and depth extent interpretation of magnetic plates.