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Measuring Points (measuring + point)

Distribution by Scientific Domains

Medical Sciences	33%
Engineering	33%

Selected Abstracts

Measurement of AC current using an optical fibre sensor

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 12 2007
C. H. Cheng
Abstract In the power industry, current is measured for metering and protection purposes. For said measurement, we demonstrated an optical fibre sensor using a single Fibre Bragg Grating (FBG) for measuring AC current for this paper. The sensor head is based on an FBG encased in a polymer-half-field metal cylinder, embedded in a magnetic material at the measuring point with the characteristics of an all-optical high pressure sensitivity. The operating mechanism is that the sensor can be attracted by the induced magnetic force created by the solenoid along one radial direction only, and responds to an axial force on the magnetic rod attached to the round plate, creating an axial attraction on the FBG. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

An evaluation of the Periotest® method as a tool for monitoring tooth mobility in dental traumatology

DENTAL TRAUMATOLOGY, Issue 2 2010
Christine Berthold
The aims of this study were to determine normal Periotest® values in the vertical and horizontal dimensions of periodontally healthy teeth in individuals aged 20,35 years and investigate the reliability of Periotest® in terms of intra-series and inter-series reproducibility before and after applying a dental trauma splint in vivo. Materials and methods:, Periotest® values were measured in periodontally healthy dental students (n = 33; mean age 24.7 years) at reproducible measuring points in the vertical and horizontal dimensions, before and after splint insertion. Three readings were taken per series to observe the intra-series reproducibility; three series were measured to test inter-series reproducibility (Friedman-test; P , 0.001). Two different wire-composite splints, 0.45 mm Dentaflex and 0.8 × 1.8 Strengtheners, were inserted and the Periotest® values were measured. Results:, The median Periotest® values before splinting were: canines -2.5, lateral incisors -0.9, and central incisors 0.0 for the vertical dimension, and canines 1.1, lateral incisors 3.2, and central incisors 3.6 for the horizontal dimension. The intra-series and inter-series Periotest® values were highly reproducible. Conclusion:, The Periotest® method provides highly reproducible results. Focused on dental trauma, the method can be applied diagnostically during the splint and follow-up period and for evaluating splint rigidity. [source]

Studying spatial and temporal dynamics of sward structure at low stocking densities: the use of an extended rising-plate-meter method

GRASS & FORAGE SCIENCE, Issue 4 2003
O. Correll
Abstract An extended rising-plate-meter method was used to study the spatial and temporal variability of the sward structure of extensively managed pastures over a grazing season. Two treatments of a long-term grazing experiment with heifers were investigated: extensive continuous grazing (EG) with a target sward height of 10 cm and intensive continuous grazing (IG) with a target sward height of 5 cm. Compressed sward height and related herbage mass (HM), dominant plant species and stage of development of phenology were determined at weekly or twice weekly intervals at fixed measuring points. The results demonstrated a strong variability in sward height and HM, especially on the EG treatment. The botanical composition of the standing herbage differed between treatments and between patches of different heights within the same treatment. In areas with a short sward, the herbage was predominantly composed of Agrostis capillaris, Festuca rubra and Trifolium repens. It was more evenly composed and also included taller growing species, such as Alopecurus pratensis and Galium mollugo, in areas with a tall sward. The area potentially available for reproductive development was high in the EG treatment and low in the IG treatment. The method employed proved suitable to provide a detailed description of the dynamics of the sward structure. [source]

Shaping ability of ProFile and K3 rotary Ni-Ti instruments when used in a variable tip sequence in simulated curved root canals

INTERNATIONAL ENDODONTIC JOURNAL, Issue 9 2004
L. R. Ayar
Abstract Aim, To compare the shaping ability of ProFile and K3 rotary Ni-Ti instruments when used in a variable tip sequence in simulated curved root canals with different curvature and radius. Methodology, ProFile or K3 .06 taper instruments were used to prepare simulated canals of 20° curvature and 5 mm radius (n = 10) and 30° curvature and 3 mm radius canals (n = 10) in resin blocks. All canals were prepared to an apical size 40 at 0.5 mm from the canal terminus using a variable tip crown-down sequence. Pre- and postinstrumentation digital images were recorded, and an assessment of the canal shape was determined using a computer image analysis program. The material removal from the inner and outer wall of the canal was measured at 28 measuring points, beginning 0.5 mm from the end-point of the canal and the data compared using the Mann,Whitney U -test. Results, In 20° and 30° canals both instruments significantly removed more (P < 0.05) material on the outer wall than the inner wall in the apical half of the canal. For ProFile files there was no significant difference in the amount of material removed on the outer canal wall between the 20° and 30° canals. However, in the K3 groups significantly more (P < 0.05) outer canal wall was removed in the apical area in 20° canals. When comparing both instruments the results showed that in 20° canals K3 instruments removed more outer and inner canal wall than ProFile instruments (P < 0.05) but that there was no significant difference (P > 0.05) between the instruments in 30° canals. Conclusion, Within the limitation of this study, both rotary nickel-titanium instruments prepared a well-shaped root canal with minimal canal transportation. [source]

Optimized damage detection of steel plates from noisy impact test

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 7 2006
G. Rus
Abstract Model-based non-destructive evaluation proceeds measuring the response after an excitation on an accessible area of the structure. The basis for processing this information has been established in recent years as an iterative scheme that minimizes the discrepancy between this experimental measurement and sequence of measurement trials predicted by a numerical model. The unknown damage that minimizes this discrepancy by means of a cost functional is to be found. The damage location and size is quantified and sought by means of a well-conditioned parametrization. The design of the magnitude to measure, its filtering for reducing noise effects and calibration, as well as the design of the cost functional and parametrization, determines the robustness of the search to combat noise and other uncertainty factors. These are key open issues to improve the sensitivity and identifiability during the information processing. Among them, a filter for the cost functional is proposed in this study for maximal sensitivity to the damage detection of steel plate under the impact loading. This filter is designed by means of a wavelet decomposition together with a selection of the measuring points, and the optimization criterion is built on an estimate of the probability of detection, using genetic algorithms. Numerical examples show that the use of the optimal filter allows to find damage of a magnitude several times smaller. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Beanspruchungsanalyse von Holzbauteilen durch 2D-Photogrammetrie

BAUTECHNIK, Issue 2 2005
Bettina Franke Dipl.-Ing.
Für die Bewertung der Tragsicherheit von Bauteilen aus Voll- und Brettschichtholz in Lasteinleitungs- und Störbereichen mittels der Bruchmechanik ist die Kenntnis von kritischen Bruchkennwerten Voraussetzung. Realitätsnahe Kennwerte können aus der Kombination experimenteller Untersuchungen zur Bestimmung der Rißaufweitung und der Rißlänge mit daran anschließender FE-Simulation gewonnen werden. Aufgrund der, bisher bei konventionellen Meßverfahren, nicht ausreichenden Zuordnung der Meßwerte taktil applizierter Meßaufnehmer lag es nahe das Rißwachstum mit Hilfe der Photogrammetrie zu untersuchen. Mit dem entwickelten Meßsystem ist nunmehr die Möglichkeit der exakten Vermessung der Rißgeometrie zur Bestimmung von bruchmechanischen Kennwerten gegeben. Zusätzlich ermöglicht der Einsatz der Photogrammetrie die Verdichtung der Anzahl variierender diskreter Meßpunkte, so daß ein deutlich vollständigeres Bild der örtlichen Verformungen gewonnen, und damit die Aussagekraft eines Versuchs wesentlich verbessert werden kann. Strain analysis of solid wood and glued laminated timber members by close range photogrammetry. The assumption of critical fracture mechanics parameters for the evaluation of the load-bearing safety of structural units of full and board laminated timber in loaded areas and disturbance ranges the use of fracture mechanics is required. Realistic parameters can be gained only from experimental investigations that are transferred to the determination of the crack opening and the crack length with subsequent FE-simulation. Due to the insufficient appropriation of measured data gained by tactile position encoders in conventional measuring procedures it is advisable to investigate crack growth with the help of the photogrammetry. Using the developed measuring system it is now possible to measure the crack geometry exactly for the determination of fracture mechanics parameters. Additionally a complete picture of the local deformations and the validity of a test can be improved considerably by the possibility of the varying number of discrete measuring points. [source]