Showing papers by "Helsinki University of Technology published in 1992"

A general approach to connected-component labeling for arbitrary image representations

Abstract: An improved and general approach to connected-component labeling of images is presented. The algorithm presented in this paper processes images in predetermined order, which means that the processing order depends only on the image representation scheme and not on specific properties of the image. The algorithm handles a wide variety of image representation schemes (rasters, run lengths, quadrees, bintrees, etc.). How to adapt the standard UNION-FIND algorithm to permit reuse of temporary labels is shown. This is done using a technique called age balancing, in which, when two labels are merged, the older label becomes the father of the younger label. This technique can be made to coexist with the more conventional rule of weight balancing, in which the label with more descendants becomes the father of the label with fewer descendants. Various image scanning orders are examined and classified. It is also shown that when the algorithm is specialized to a pixel array scanned in raster order, the total processing time is linear in the number of pixels. The linear-time processing time follows from a special property of the UNION-FIND algorithm, which may be of independent interest. This property states that under certain restrictions on the input, UNION-FIND runs in time linear in the number of FIND and UNION operations. Under these restrictions, linear-time performance can be achieved without resorting to the more complicated Gabow-Tarjan algorithm for disjoint set union.

Glottal wave analysis with Pitch Synchronous Iterative Adaptive Inverse Filtering

Abstract: A new glottal wave analysis method, Pitch Synchronous Iterative Adaptive Inverse Filtering (PSIAIF) is presented. The algorithm is based on a previously developed method, Iterative Adaptive Inverse Filtering (IAIF). In the IAIF-method the glottal contribution to the speech spectrum is first estimated with an iterative structure. The vocal tract transfer function is modeled after eliminating the average glottal contribution. The glottal excitation is obtained by cancelling the effects of the vocal tract and lip radiation by inverse filtering. In the new PSIAIF-method the glottal pulseform is computed by applying the IAIF-algorithm twice to the same signal. The first IAIF-analysis gives as a result a glottal excitation that spans over several pitch periods. This pulseform is used in order to determine positions and lengths of frames for the pitch synchronous analysis. The final result is obtained by analysing the original speech signal with the IAIF-algorithm one fundamental period at a time. The PSIAIF-algorithm was applied in glottal wave analysis using both synthetic and natural vowels. The results show that the method is able to give a fairly accurate estimate for the glottal flow excluding the analysis of vowels with a low first formant that are produced with a pressed phonation type.

Effect of surface processing on the attachment, orientation, and proliferation of human gingival fibroblasts on titanium.

Abstract: The adhesion, orientation, and proliferation of human gingival fibroblasts was studied on electropolished (elpTi), etched (etchTi), and sandblasted (sblTi) titanium surfaces. The texture, chemical state, and composition of the titanium surfaces were analyzed using a surface tracing instrument and electron spectroscopy for chemical analysis. Considerable differences were evident in the surface texture and chemical composition of the differently treated titanium plates. Electropolishing produced the smoothest and cleanest surface. Human gingival fibroblasts attached, spread, and proliferated on all titanium surfaces. However, cells on elpTi exhibited an extremely flat morphology and seemed to form cellular bridges with adjacent cells, whereas the etchTi and sblTi surfaces harbored both round and flat cells with many long processes. Cells on elpTi appeared to grow in thick layers with no specific orientation, whereas on etchTi surfaces they were migrating along the parallel, irregular minor grooves caused by mechanical polishing, and on sblTi surfaces they seemed to grow in clusters. Stress-fiber type actin bundles and vinculin-containing focal adhesions were present in cells spreading on elpTi and etchTi surfaces but not in cells spreading on sblTi surfaces. Cell shape, orientation, and proliferation appear to depend on the texture of the titanium surface and probably also on the properties of the oxide layer and adjacent bulk material. Our findings suggest that smooth or finely grooved titanium surfaces could be optimal in implants adjacent to soft tissues as they support the attachment and growth of human gingival fibroblasts.

On optimal population size of genetic algorithms

Abstract: A description is given of the results of experiments to find the optimum population size for genetic algorithms as a function of problem complexity. It seems that for moderate problem complexity the optimal population size for problems coded as bitstrings is approximately the length of the string in bits for sequential machines. This result is also consistent with earlier experimentation. In parallel architectures the optimal population size is larger than in the corresponding sequential cases, but the exact figures seem to be sensitive to implementation details. >

Molecular-dynamics simulation of the growth of diamondlike films by energetic carbon-atom beams

Abstract: The growth of diamondlike films and overlayers by the depsotion of energetic carbon atoms has been investigated by molecular-dynamics simulations. The interatomic many-atom potential suggested by Tersoff is used. The structurel analysis of the grown films shows that there is an energy window between 40 and 70 eV for the deposited atoms where the growth most closely results in dense diamondlike structure. This observation supports earlier experimental suggestions for optimal deposition conditions.

Sound rendering

Abstract: We present a general methodology to produce synchronized soundtracks for animations. A sound world is modeled by associating a characteristic sound for each object in a scene. These sounds can be generated from a behavioral or physically-based simulation. Collision sounds can be computed from vibrational response of elastic bodies to the collision impulse. Alternatively, stereotypic recorded sound effects can be associated with each interaction of objects. Sounds may also be generated procedurally, The sound world is described with a sound event file, and is rendered in two passes. First the propagation paths from 3D objects to each microphone are analyzed and used to calculate sound transformations according to the acoustic environment. These effects are convolutions, encoded into two essential parameters, delay and attenuation of each sound. Timeciependency of these two parameters is represented with key frames, thus being completely independent of the original 3D animation script. In the second pass the sounds associated with objects are instantiated, modulated by interpolated key parameters, and summed up to the final soundtrack. The advantage of a modular architecture is that the same methods can be used for all types of animations, keyframed, physically-based and behavioral. We also discuss the differences of sound and light, and the remarkable similarities in their rendering processes. CR

LVQPAK: A software package for the correct application of Learning Vector Quantization algorithms

Abstract: An overview of the software package LVQPAK, which has been developed for convenient and effective application of learning vector quantization algorithms, is presented. Two new features are included: fast conflict-free initial distribution of codebook vectors into the class zones and the optimized-learning-rate algorithm OLVQ1. >

Comparison of algorithms for retrieval of snow water equivalent from Nimbus-7 SMMR data in Finland

Abstract: The correlation between the brightness temperature of snow-covered terrain (dry snow) and the snow-water equivalent in Finland was investigated using Nimbus-7 SMMR data. The satellite data set covers the winters of 1978-9 through 1981-2. The correlation analysis was performed for 17 different brightness temperature functions, each involving one or several frequencies and polarizations. The highest correlation coefficients between the satellite-derived brightness temperature functions and the manually measured snow-water equivalent values were obtained by using the brightness temperature difference between 37 GHz and either 18 GHz or 10.7 GHz, vertical polarization. >

Effects of compatibilizers on the properties of polyamide/polypropylene blends

Abstract: Compatibilization of polyamide 6/isotactic polypropylene blends was investigated by mechanical, morphological, thermal, and rheometrical methods. The primary objective was to obtain blends combining the desirable properties of the two components. Four compatibilizers including maleic anhydride, fumaric acid, or glycidyl functionalities were applied at two concentrations (5 and 10%). Maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer (SEBS-g-MAH) was observed to give excellent mechanical properties, especially at high polyamide/polypropylene ratios. The correlation between morphology and mechanical and rheological properties is discussed, and the interesting effect of blending on the kinetics of crystallization is noted.

The problem of membrane locking in finite element analysis of cylindrical shells

Abstract: We analyse the problem of membrane locking in (h, p) finite element models of a thin hemicylindrical shell roof loaded by a smoothly varying normal pressure distribution. We show that in the standard finite element method, locking occurs especially at low values ofp and when the finite element grid is not aligned with the axis of the cylinder. A general strategy of avoiding locking by using modified bilinear forms is introduced, and a special implementation of this strategy on aligned rectangular grids is considered.

The effect of air humidification on symptoms and perception of indoor air quality in office workers: a six-period cross-over trial.

Abstract: The objective of this study was to evaluate the effect of air humidification on (a) the dryness of the skin and mucosa, (b) allergic and asthmatic reactions, and (c) the perception of indoor air quality. A total of 290 office workers at the Pasila Office Center were included in a six-period cross-over trial. One wing of the building was operated with 30-40% humidification, and the other wing operated under conditions of no air humidification (relative humidity from natural conditions was 20-30%). The length of each study period was 1 work wk. The workers were instructed to keep a structured daily diary of their symptoms, their perception of the indoor air, and potential determinants of the symptoms. A total of 211 (72.6%) workers who returned at least two weekly diaries, and who had experienced both humidified and nonhumidified conditions, were included in the analyses. The primary outcome--dryness symptom score--was characterized by dryness, irritation or itching of the skin and eyes, dryness or irritation of the throat, and nasal dryness. Means of the daily symptom scores and perception ratings during the humidified and nonhumidified periods were calculated for each participant, and intraindividual differences in the means were used to assess the effect of air humidification. The dryness symptom score was significantly smaller during the humidified phase than during the reference phase (paired t test; p less than .05). Allergic symptoms that were considered as a separate outcome, a sensation of dryness, and draft were also significantly less frequent during the humidification phase (p less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Injection‐moulded blends of a thermotropic liquid crystalline polymer with polyethylene terephthalate, polypropylene, and polyphenylene sulfide

Abstract: Structure–property relationships were investigated for blends of a polyester-type thermotropic liquid crystalline polymer (LCP) with polyethylene terephthalate (PET), polypropylene (PP), and polyphenylene sulfide (PPS). The polymers were melt blended in a twin-screw extruder and the blends were extruded to strands of different draw ratios. Tensile properties of the blends were determined as a function of LCP content and draw ratio and compared with the results of morphological and rheological analyses. In general, the strength and stiffness of the matrix polymers were improved with increasing LCP content and draw ratio. At a draw ratio of 11, the blends of PET/30 wt % LCP exhibited a tensile strength about three times and an elastic modulus nearly four times that of pure PET. All blends exhibited a skin/core morphology with thin fibrils in the skin region. The formation and the sizes of the fibril-like LCP domains in the matrices were found to depend on LCP content and the viscosity ratio of the blend components.

Noise reduction in recursive digital filters using high-order error feedback

Abstract: The problem of solving the optimal (minimum-noise) error feedback coefficients for recursive digital filters is addressed in the general high-order case. It is shown that when minimum noise variance at the filter output is required, the optimization problem leads to set of familiar Wiener-Hopf or Yule-Walker equations, demonstrating that the optimal error feedback can be interpreted as a special case of Wiener filtering. As an alternative to the optimal solution, the formulas for suboptimal error feedback with symmetric or antisymmetric coefficients are derived. In addition, the design of error feedback using power-of-two coefficients is discussed. The efficiency of high order error feedback is examined by test implementations of the set of standard filters. It is concluded that error feedback is a very powerful and versatile method for cutting down the quantization noise in any classical infinite impulse response (IIR) filter implemented as a cascade of second-order direct form sections. The high-order schemes are attractive for use with high-order direct form sections. >

Transboundary air pollution and soil acidification: A dynamic analysis of an acid rain game between Finland and the USSR

Abstract: Transboundary air pollution is analysed as a dynamic game between Finland and the nearby areas of the Soviet Union. Sulphur emissions are used as the environmental control variables and the acidities of the soils as the state variables. Acidification is consequently considered to be a stock pollutant having long-lasting harmful effects on the environment. The state dynamics consist of two relationships: first, of a sulphur transportation model between the regions and, second, of a model describing how the quality of the soil is affected by sulphur deposition. The countries are assumed to be interested in maximizing the net benefits from pollution control as measured by the impacts on the values of forest growth net of the abatement costs. Cooperative and noncooperative solutions of the game are compared to assess the benefits of bilateral cooperation. Using empirical estimates of abatement costs, acidification dynamics and impacts on forest growth it is shown that cooperation is beneficial to Finland but not to the Soviet Union. Consequently, Finland has to offer monetary compensation to induce her neighbor to invest in environmental protection.

Magnetoencephalography: a tool for functional brain imaging.

Abstract: At present, one of the most promising windows to the functional organization of the human brain is magnetoencephalography (MEG). By mapping the magnetic field distribution outside the head the sites of neural events can be located with an accuracy of a few millimeters and the temporal evolution of the activation can be traced with a millisecond resolution. This paper reviews some forward field calculation approaches suitable for the interpretation of the brain's electromagnetic signals. Inverse modelling with multiple dipoles is described in detail. An example of the analysis of the somatosensory evoked-responses illustrates the potential of multiple signal classification (MUSIC) algorithm in finding optimal dipole positions.

A general approach to network analyzer calibration

Abstract: A general-purpose algorithm, the TCX algorithm, for network analyzer and test fixture calibration is presented. The algorithm can handle most of the existing calibration methods, including symmetrical test fixtures. Any combination of one-port or two-port standards can be used. There is a possibility of partial self-calibration, if one of the standards is a two-port network or a through connection. The algorithm is applied to get simple equations covering the TSD, LDX (LRL), LAX, and LMX methods (X being an unknown one-port or symmetrical two-port network). A transmission path is allowed between the ports of standard X. In the TSD method, the delay line can be replaced with an attenuation network or with a matched load; also, the through line can have an unknown delay line and attenuation. A method of root choice for LRL and similar methods in conjunction with test fixtures is described. The method of least-squares-fit can be applied, when redundant data are available. It gives an essential improvement of accuracy in the simulation of a symmetrical test fixture. >

Gallium vacancies and gallium antisites as acceptors in electron-irradiated semi-insulating GaAs.

Abstract: Positron-lifetime measurements show that acceptors are produced in semi-insulating GaAs by 15-MeV electron irradiation at 20 K Two types of acceptors can be separated The first ones are negative vacancy-type defects which anneal out over a very broad range of temperature between 77 and 500 K The second ones are negative ion-type defects which are stable still at 450 K The data show that these two types of defects are independent and do not form close pairs We attribute both to gallium-related defects We identify the ion-type acceptors as isolated gallium antisites The vacancy-type acceptors are identified as gallium vacancies which are isolated or involved in negatively charged complexes The introduction rate of the gallium antisite is estimated to be 18\ifmmode\pm\else\textpm\fi{}03 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ in the fluence range ${10}^{17}$--${10}^{18}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ for 15-MeV electron irradiation at 20 K

Synthetic diffractive optics in the resonance domain

Abstract: Resonance-domain diffractive optics covers the region where the characteristic feature sizes in the surface-relief modulation structure of the diffractive optical element are comparable to the wavelength of light; it may be viewed as a bridge between synthetic holography and the electromagnetic theory of diffraction gratings and rough surfaces. We consider the problem of synthesizing, in the framework of the electromagnetic theory, various types of periodic resonance-domain diffractive optical elements that utilize several diffraction orders. Parametric optimization is used to design one-to-N fan-out elements, N-to-N star couplers, and polarization-controlled optical beam splitters and switches with close to 100% efficiencies and no undesired diffraction orders in the image half-space. Reflection-type fan-out gratings with six and seven output beams are demonstrated experimentally at λ = 10.6 μm.

Effect of enzymatic interesterification on the melting point of tallow-rapeseed oil (LEAR) mixture

Abstract: To reduce the melting point of a tallow-rapeseed oil mixture, the triglyceride composition of the mixture was altered by enzymatic interesterification in a solvent-free system. The interesterification and hydrolysis were followed by melting point profiles and by free fatty acid determinations. The degree of hydrolysis was linearly related to the initial water content of the reaction mixture. The rate of the interesterification reaction was influenced by the amount of enzyme but not much by temperature between 50 and 70°C. The melting point reduction achieved by interesterification depended on the mass fractions of the substrates: the lower the mass fraction of tallow, the larger the reduction of the melting point.

Process State Monitoring Using Self-Organizing Maps

Abstract: Self-organizing map algorithm has the ability to create a model for a system that is not exactly known a priori Using this kind of model we can classify the system states and detect the abnormal ones In this paper, an application of the feature map to detect operational states of a device is presented The features used in the map are the measurements from the device describing its operational and environmental parameters

Magnetoencephalographic localization of epileptic cortex—impact on surgical treatment

Abstract: A 24-channel, planar, superconducting quantum interference device gradiometer, sampling a fourth of the head surface over brain tissue, was used to determine the site of an epileptic focus in a 36-year-old woman with intractable complex partial epilepsy. The other presurgical findings appeared divergent: a large arachnoid cyst over the right parietal convexity, dissimilar interictal electroencephalographic patterns, and several neuropsychological dysfunctions. The equivalent current sources of magnetoencephalographic spikes were in the right posterior temporal region of the cortex, 4 cm apart from the cyst. Surgical exploration of the area pinpointed by magnetoencephalography revealed a pachygyric patch of cortex displaying focal discharges on the electrocorticogram. After resection, a dramatic reduction of seizures occurred. The good agreement between electrocorticography and magnetoencephalography warrants future investigation of multichannel magnetoencephalography as a potential alternative to invasive presurgical recordings.

Combined spin-mass vortex with soliton tail in superfluid 3He-B.

Abstract: We have observed spin-mass vortices (SMV) in superfluid $^{3}\mathit{B}$. The SMV is a combined topological object made up of a vortex line with mass current and a disclination line with spin current. It is also a termination line of a planar defect, the so-called \ensuremath{\theta} soliton. The SMVs are bound either as pairs or to the container wall by the soliton. They are nucleated when a rotating $^{3}\mathrm{He}$ sample cools slowly through the A\ensuremath{\rightarrow}B phase transition. The identification of the SMV is based on the NMR signatures of the soliton.

Parametric optimization of multilevel diffractive optical elements by electromagnetic theory

Abstract: To maximize the efficiency of dielectric diffractive optical elements, we optimized the local groove shape using the rigorous diffraction theory of multilevel surface-relief gratings.

Karl F. Lindman: the last Hertzian, and a harbinger of electromagnetic chirality

Abstract: The research career of Karl F. Lindman, who has widely been referred to as being the first to demonstrate the effect of a chiral medium on electromagnetic waves, is described. During the first half of this century, Lindman completed an extensive research career, using essentially the same methods as Heinrich Hertz did in his time. His work is reviewed, focusing on his chirality studies. >