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Showing papers by "Helsinki University of Technology published in 1978"


Journal ArticleDOI
TL;DR: In this paper, a technique is presented to enable the state space of a Harris recurrent Markov chain to be split in a way, which introduces into the split state space an "atom" which can be used for analysis of Markov chains on a general state space.
Abstract: A technique is presented, which enables the state space of a Harris recurrent Markov chain to be “split” in a way, which introduces into the split state space an “atom”. Hence the full force of renewal theory can be used in the analysis of Markov chains on a general state space. As a first illustration of the method we show how Derman's construction for the invariant measure works in the general state space. The Splitting Technique is also applied to the study of sums of transition probabilities.

326 citations


Journal ArticleDOI
TL;DR: An Archean age for Finnish rocks in the range 2500-3000 Ma has been determined north of the NW-striking Ladoga-Raahe shear belt as discussed by the authors.

57 citations


Journal ArticleDOI
TL;DR: In this paper, a review of density matrix methods for nonlinear spectroscopy is presented, where it is argued that the two main characteristics of nonlinear spectrum are spontaneous emission and mechanical effects, i.e. Doppler shifts, recoil effects and light pressure.

55 citations


Journal ArticleDOI
TL;DR: In this paper, the transition temperature of 3He is calculated as a function of the size of an infinitely long cylindrical pore or an infinite slab container with diffusely scattering walls.
Abstract: The transition temperature of superfluid 3He is calculated as a function of the size of an infinitely long cylindrical pore or an infinite slab container with diffusely scattering walls. We present the exact asymptotic behavior for large and small containers and a full numerical calculation for intermediate sizes.

53 citations


Journal ArticleDOI
TL;DR: In this paper, the phase-separation phenomena in the Li2OSiO2 glass were studied by positron lifetime and annihilation lineshape measurements, and the results were consistent with scanning electron and optical micrographs.
Abstract: The crystallization and phase-separation phenomena in the Li2OSiO2 glass are studied by positron lifetime and annihilation lineshape measurements Analysis of the kinetic data shows three-dimensional morphology of growing crystals Phase-separation is seen to increase the density of crystal nuclei and the rate of volume crystallization, but it does not affect the morphology In addition, surface crystallization is detected in glasses with small degrees of phase-separation The results are consistent with scanning electron and optical micrographs

50 citations


Journal ArticleDOI
TL;DR: A strong decrease in voluntary ethanol drinking by the low-protein group may have been caused by the increased acetaldehyde accumulation in the blood, but a particularly low blood acetaldehyde level was not one of the factors inducing excessive ethanol drinking in the high-fat group.
Abstract: 1. The voluntary ethanol consumption, ethanol elimination rate and blood acetaldehyde level after intraperiotoneal injection of ethanol were studied in rats receiving diets with highly imbalanced proportions of dietary protein, carbohydrate and fat. 2. The rats, which received the low-protein diet containing 0.05 of the total energy as protein, 0.80 as carbohydrate and o.15 as fat, drank only approximately half as much ethanol as did the control group, which received 0.30 of its total food energy from protein, 0.55 from carbohydrate and 0.15 from fat. Ethanol elimination rate in the low-protein group was decreased and the blood acetaldehyde level after ethanol injection was markedly increased. 3. On the high-fat diet, which contained 0.30 of the total energy from protein, 0.05 from carbohydrate and 0.65 from fat, the rats drank significantly more ethanol than did the rats on the control diet; their ethanol elimination rate was decreased but their blood acetaldehyde level was not affected. 4. In conclusion, the strong decrease in voluntary ethanol drinking by the low-protein group may have been caused by the increased acetaldehyde accumulation in the blood, but a particularly low blood acetaldehyde level was not one of the factors inducing excessive ethanol drinking in the high-fat group.

41 citations


Journal ArticleDOI
TL;DR: Four variations of an algorithm based upon graph theory are developed for solving the facilities design problem, which involves locating economic activities on a floor within a building in such a manner to optimize an appropriate measure of effectiveness such as the total cost of materials handling.
Abstract: Four variations of an algorithm based upon graph theory are developed for solving the facilities design problem. The facilities design problem involves locating economic activities, each of which requires a given amount of space, on a floor within a building in such a manner to optimize an appropriate measure of effectiveness such as, for example, the total cost of materials handling. This problem has been called the location-allocation problem in some of the earlier management science literature. The algorithm uses strings to represent the graphs in order to be able to handle the computing more effectively. The algorithm is illustrated throughout the article by an example. Experience with both FORTRAN and PL/1 is reported. The topic is likely to be of interest to facilities designers, graph theoreticians and computer scientists.

38 citations


Journal ArticleDOI
TL;DR: In this paper, the first measurements of negative ion motion in the superfluid phases of 3He and in the normal phase below 17 mK were made using a pulsed NMR platinum powder thermometer.
Abstract: We report the first measurements of negative ion motion in the superfluid phases of 3He and in the normal phase below 17 mK. Refrigeration was achieved with nuclear demagnetization of copper and we used a pulsed NMR platinum powder thermometer immersed in the liquid. In the A phase the longitudinal resonance frequency provided an additional high-resolution thermometer. In the normal phase we observed a strictly temperature-independent mobility. In the superfluid phases we found two velocity regimes. For small applied electric fields the velocity is a linear function of the field and the corresponding mobility increases monotonically toward lower temperatures. At high electric fields the velocity is a nonlinear function of the field as a result of the pair-breaking effect of the moving ion. Available theoretical calculations are only in partial agreement with our results.

37 citations


Journal ArticleDOI
TL;DR: In this article, the authors compared the phenomenological equations for diffusion and electric conduction in ionic and component forms and concluded that electric convection and diffusion can be treated as two independent phenomena which are superimposed.

35 citations


Journal ArticleDOI
TL;DR: A model of the control of the respiratory cycle pattern is presented in which the airflow shape is determined by a dynamic optimization problem, and successfully predicts various patterns of spontaneous breathing during both inspiration and expiration.
Abstract: A model of the control of the respiratory cycle pattern is presented in which the airflow shape is determined by a dynamic optimization problem. The inspiratory and expiratory phases have different performance criteria both of which are related to the oxygen cost of breathing, and to the minimization of tissue damage and control difficulties. The model successfully predicts various patterns of spontaneous breathing during both inspiration and expiration. The effects of applying elastic and resistive loads to the respiratory system can also be predicted. The model performance is in good agreement with the experimental observation that increasing resistance makes the airflow patterns more rectangular.

35 citations


Journal ArticleDOI
TL;DR: Collisionally aided redistribution of scattered laser light is suggested as a method to cool or heat gaseous samples in this article, where the efficiency is evaluated and restricting conditions are considered Some potential applications are given


Journal ArticleDOI
TL;DR: In this article, the authors formulated the theory of spontaneous decay with recoil included, where the vacuum is treated as a reservoir absorbing the spontaneously emitted photons and assumed no correlation between consecutive emission events and zero probability of photon reabsorption.
Abstract: In this paper we formulate the theory of spontaneous decay with recoil included. The vacuum is treated as a reservoir absorbing the spontaneously emitted photons. This assumes no correlation between consecutive emission events and zero probability of photon reabsorption. The spontaneous emission is assumed independent of the strong fields present. Some simple consequences of the theory are discussed. We solve the two-level system with one strong running wave and plot the velocity distribution of the two levels. We find modifications both of the average velocity and the line shapes. In particular the lower level Bennett hole experiences a narrowing in certain parameter ranges.

Journal ArticleDOI
TL;DR: In this paper, the effects of strain, strain rate and deformation heating in tensile testing of sheet steel are numerically analyzed. And the results show that the stretchability of sheet metals can be improved by using very low forming speeds or more economically by using an effective cooling system.
Abstract: The effects of strain, strain rate and deformation heating in tensile testing of sheet steel are numerically analyzed. An experimentally determined strain-hardening formula is used as a basis of the calculation. The effects of heat conduction and free or forced con-vection during the test are taken into account by using the approximate solution method originally given by Bishop for metal extrusion. The calculated values agree well with the experimental data. It is shown that deformation heating considerably affects the uni-form strain. Consequently the stretchability of sheet metals can be improved by using very low forming speeds or more economically by using an effective cooling system.

Journal ArticleDOI
TL;DR: In this paper, an expansion in T/sub c/T/sub F was used to study the influence of strong coupling effects on the linear response of superfluid /sup 3/He.
Abstract: We use an expansion in T/sub c//T/sub F/ to study the influence of strong-coupling effects on the linear response of superfluid /sup 3/He. Our results indicate that the enhancement of the order parameter gives the major strong-coupling corrections to the magnetic susceptibilities, bending energies, and superfluid density. The additional ''nontrivial'' strong-coupling corrections depend sensitively on currently unknown details of the quasiparticle interactions. Hence, precise measurements of the response coefficients can provide additional information about the quasiparticle interactions.



Journal ArticleDOI
TL;DR: In this paper, the authors measured the mobility of positive ions in the normal and superfluid phases of 3He at several pressures, and observed the anisotropic mobility in the A phase and the Landau critical velocity for pair-breaking in both superfluid and normal phases.
Abstract: The mobility of positive ions has been measured in the normal and superfluid phases of 3He at several pressures. Below 100 mK the normal phase mobility increases logarithmically with decreasing temperature down to the superfluid transition temperature T c; it shows an anomalous jump near 100 mK. At low temperatures the drift velocity is nonlinear for electric fields exceeding 30 V/cm. In the superfluid the mobility, normalized to its value at T c, is much less than for negative ions. We have also observed the anisotropic mobility in the A phase and the Landau critical velocity for pair-breaking in both superfluid phases.

Journal ArticleDOI
TL;DR: In this paper, the authors considered the modifications of the atomic velocity distribution imposed by a standing wave and derived the rate equation limit for these equations and showed how it can be generalized to treat a broadband source of radiation.
Abstract: This paper considers the modifications of the atomic velocity distribution imposed by a standing wave. The recoil due to induced and spontaneous processes provides an effective force on the particles. We formulate the general problem of a two-level atom in the field of two counter-propagating waves. We derive the rate equation limit for these equations and show how it can be generalized to treat a broad-band source of radiation. The connection with generalized relaxation theory is discussed. The ensuing integral equations are solved numerically for various cases of cooling and heating.

Journal ArticleDOI
TL;DR: In this article, the authors derived relativistic correction terms up to the second order for the kinetic energy of an electron travelling along the circular central trajectory of a toroidal analyzer.


Journal ArticleDOI
TL;DR: An automatic method using dyed cellulose as a substrate was developed to determine the solubilizing activity of a cellulase complex and enzyme activity was successfully assayed during fermentation.
Abstract: An automatic method using dyed cellulose as a substrate was developed to determine the solubilizing activity of a cellulase complex. The automatic analyzer was connected to a fermentor and enzyme activity was successfully assayed during fermentation. A useful sampling arrangement was developed and the analysis was sensitive enough to make a short reaction time possible. Cellulase production with Trichoderma viride was used as a model process.

Journal ArticleDOI
TL;DR: In this paper, relativistic correction terms up to the second order are derived for the kinetic energy of an electron travelling along the central trajectory, which crosses the non-relativistic foci of electrostatic parallel plate and cylindrical mirror analyzers.

Journal ArticleDOI
TL;DR: In this article, the Sokli carbonatite massif has been studied and the temperature order of the stages is derived by combining the mean δ 34S values determined by temperature, relative fO2, and pH of the silico-carbonite fluids with the FeOS mineral relations.

Journal ArticleDOI
TL;DR: In this paper, 3-Indolizinyl acetates and propionates 4 react with ethylenic and acetylenic ketones or carboxylic esters to give 1-acylpyrrolo[2,1,5-cd]indolizines 5-12 in excellent yields.

Journal ArticleDOI
TL;DR: Theoretical and experimental studies of UHF and microwave radiometry to sense remotely the thickness and other characteristics of low-salinity (less than one per mille) sea ice are described in this paper.
Abstract: Theoretical and experimental studies of ultra-high-frequency (UHF) and microwave radiometry to sense remotely the thickness and other characteristics of low-salinity (less than one per mille) sea ice are described. The experimental studies used a 600-MHz and a multichannel, multibeam, 4.7-GHz radiometer carried by a helicopter to measure the brightness temperature of different types of sea ice in the Gulf of Bothnia in 1975 and 1976.

Journal ArticleDOI
TL;DR: In this paper, an analysis of the model performance under normal and abnormal conditions is presented, and theoretical predictions of the effects of added resistance loads are given for three different values of the elastance.
Abstract: An analysis of the model performance under normal and abnormal conditions is presented. The effects of changes in the alveolar ventilation rate on the inspiratory time, expiratory time, pause period, respiratory frequency, tidal volume, dead space volume and change in end expiratory level are considered. Moreover, theoretical predictions of the effects of added resistance loads are given. The results are displayed for three different values of the elastance. Comparisons with available experimental data show that the model predictions are in good accordance with observations under both normal and loaded conditions. None of the previous models have been able to reproduce the overall pattern of breathing as accurately as the present hierarchical model.

Journal ArticleDOI
TL;DR: A discussion of theoretical treatments of atomic rearrangement processes accompanying β-decay is presented in this article, where a schematic model for K-shell ejection or excitation is developed and the expected accuracy of this model and other theoretical treatments using approximate wave functions is discussed.

Proceedings ArticleDOI
01 Apr 1978
TL;DR: It is demonstrated that a vector space projector named Novelty Filter can be used to perform the segmentation of speech into phonemes using the Spectral decomposition of the speech waveform.
Abstract: Temporal segmentation of the acoustic wave-form into distinct, recognizable units is an unavoidable task in machine recognition of continuous speech. In this paper it is demonstrated that a vector space projector named Novelty Filter can be used to perform the segmentation of speech into phonemes. A Spectral decomposition of the speech waveform, performed by an analog filter bank, is continuously analyzed at regular sampling intervals for its degree of "novelty" with respect to a set of stationary prototype phonemes. The distance of the sampled vectors from the subspace spanned by all the prototype vectors is given by the Novelty Filter, and the maxima of this distance then indicate the transition regions between successive phonemes.

Journal ArticleDOI
TL;DR: In this article, the progress, difficulties and role of control engineering in fermentation processes are discussed according to the authors' experience and opinions, and a brief survey on dynamic analysis and modelling of fermentations is presented.