Background/aims: Topometry is one of the most relevant methods for biophysical research on skin in dermatologic and cosmetic science, because it relates very closely to the perceived quality of skin. Taking silicon replicas of skin sites under investigation and measuring those imprints with mechanical or optical profilometers is still the most frequently used method. Direct measurement of the topography of human skin in vivo by active image triangulation avoids the need to make replicas and seems to be a promising alternative. Methods: The introduction of active image triangulation in conjunction with phase‐shift techniques in skin topometry enables a fast and non‐invasive measurement of the skin surface in vivo. The main attribute of the proposed system is the projection of a regular sinusoidal intensity pattern with a sophisticated digital projection device onto the surface of skin under a certain angle of incidence. The height information of the structured surface is coded in the distorted intensity pattern, which is recorded by an appropriate video technique. Results: Successful in vivo measurements of selected body sites and measurements on scar, nevus, wound and wrinkles are presented in this paper. Furthermore, irritation of skin, influence of hydration of skin, and differences between youthful and elderly skin can be detected in the measurement results of the new optical system. Conclusions: For measuring the topog raphy of human skin, active image triangulation is appropriate both for macrotopometry (nevus, scar, wound) and for microtopometry (casts, selected body sites). This new non‐contact technique allows dynamic measurements of alterations in skin topography as a consequence of certain treatments (e.g., application of ingredient, hydration of skin) without removal of corneocytes or scales. Optical three‐dimensional (3D) topometry using active image triangulation appears to offer a significant improvement in speed and flexibility, providing a fast and accurate analysis of skin surface topography.
in Hamburg tätig, jetzt in der Bundeswehr. Die Gas-Pfad-Analyse ist ein nützliches Hilfsmittel bei der Modellbildung für Triebw erks-und Gasturbinen. Die Modelle werden zur zustandsbezogenen Diagnose dieser Maschinen verwendet. Bei einer Diagnose verfälschen oftmals Fehler der Meßsensoren die wahren Zustände der Anlagen. Die Detektion und Kompensation von Sensorfehlern ist daher eine wichtige Aufgabe im Bereich der Diagnose. Bei Triebwerken mit mehreren Arbeitspunkten wird das Problem modellbasiert gelöst; hierfür existieren bereits leistungsfähige Programmpakete. Bei Gasturbinen mit nur einem Arbeitspunkt ist ein wissensbasiertes Vorgehen erforderlich. Hierfür wurdeein Expertensystem entwickelt, weichesein Regelwerk verwendet, das die Unscharfen des Systems berücksichtigt. Dieses Expertensystem wird in dieser Arbeit vorgestellt. Seine Leistungsfähigkeit wird anhand einer in einem Wärmekraftwerk eingesetzten Gasturbine dargestellt. Knowledge-based sensor fault detection for gasturbines under consideration of uncrisp methodsGas path analysis is a useful aid in modelling for jet engines and gas turbines. The models are used to diagnose the condition of these machines. However, errors from the measuring sensors distort the true states of the equipment.The detection and compensation of sensor errors is thus an important task in the field of diagnosis. In jet engines with several working points the problem is solved by a model-based procedure; powerful software packages already exist for this purpose. A knowledge-based procedure is required for gas turbines with only one working point. To this end an expert system has been developed using a rule network which considers the uncertanties of the system. This expert system is to be presented in this paper. Its performance capabilities will be illustrated by means of a gas turbine used in a thermal power station.
In view of treatment effects of cosmetics, quality management becomes more and more important. Due to efficiency reasons it is desirable to quantify these effects and predict them as a function of time. For this, a mathematical model of the skin's surface (epidermis) is needed. Such a model cannot be worked out purely analytically. It can only be derived with the help of measurement data. The signals of interest as output of different measurement devices consist of two parts: noise of high (spatial) frequencies (stochastic signal) and periodic functions (deterministic signal) of low (spatial) frequencies. Both parts can be separated by correlation analysis.The paper introduces in addition to the Fourier Transform (FT) with the Wavelet Transform (WT), a brand new, highly sophisticated method with excellent properties for both modeling the skin's surface as well as evaluating treatment effects. Its main physical advantage is (in comparison to the FT) that local irregularities in the measurement signal (e.g. by scars) remain at their place and are not represented as mean square values as it is the case when applying the FT. The method has just now been installed in industry and will there be used in connection with a new in vivo measurement device for quality control of cosmetic products.As texture parameter for an integral description of the human skin the fractal dimension D is used which is appropriate for classification of different skin regions and treatment effects as well.
Die Veränderung einer Oberfläche infolge äußerer Einflüsse ist häufig Gegenstand von Untersuchungen im Rahmen der Produktevaluierung und Qualitätssicherung. Der Zustand rauer Oberflächen wird dabei üblicherweise durch nichtlokale Kenngrößen bzw. Texturparameter beschrieben und über einen definierten Zeitraum beobachtet. Veränderungen der Oberfläche können so zwar auf einfache Weise quantitativ erfasst werden, jedoch stößt dieser Ansatz bei genaueren Untersuchungen schnell an seine Grenzen. Eine lokale und damit detaillierte Analyse von Oberflächenveränderungen im Vergleich zum Ausgangszustand ist auf diese Weise kaum möglich. Darüber hinaus beschreiben nichtlokale Kenngrößen und Parameter die Veränderung einer Oberfläche oftmals nur unzureichend. Das hier vorgestellte Verfahren zur Arealverfolgung in topographischen Messdaten erlaubt dagegen eine lokale Beschreibung von Oberflächenveränderungen und eine Auswertung über identische Areale bzw. Punktmengen, obwohl das Messobjekt während der Testreihe mehrfach aus dem Messaufbau genommen und neu ausgerichtet werden muss. Die Berechnung eines Verschiebungsvektorfeldes zwischen zwei Messungen bildet dafür die Grundlage. Am Beispiel der menschlichen Hautoberfläche wird gezeigt, wie Deformationen rauer, elastischer Oberflächen erkannt und ausgewertet werden können.The alteration of a surface caused by external influences is a frequently investigated subject in product evaluations or quality control. The most common approaches for describing the properties of rough surfaces are based on the calculation of non-local parameters. These parameters represent the state of the surface and are recorded during a predefined test period. Changes of the surface topography can be quantified easily by this approach but the method also has several drawbacks when detailed results are required. Non-local parameters do not allow a local and detailed analysis of alterations of surface topographies. Furthermore in some applications they describe changes of the surface insufficiently only. In this paper an approach for area tracking in topographical measurement data is presented which allows local and detailed description of changes of a surface topography and data analysis using identical areas or point sets despite the fact that the measurement object has to be placed under the measurement system for several times. The approach is based on the calculation of a displacement vector field between two measurements. The surface of human skin serves as an example to demonstrate how to detect and to analyse the deformation of a rough elastic surface.
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