scholarly journals Drifting-snow acoustic detector: experimental tests in La Molina, Spanish Pyrenees

1998 ◽  
Vol 26 ◽  
pp. 221-224 ◽  
Author(s):  
D. Font ◽  
F. Naaim-Bouvet ◽  
M. Roussel
Keyword(s):  
Experimental Tests ◽  
Electrical Signal ◽  
Average Height ◽  
Acoustic Detector ◽  
Drifting Snow ◽  
Spanish Pyrenees ◽  
Wind Velocities ◽  
Drift Density ◽  
Exact Amount

A new gauge to detect drifting snow has been tested at an experimental site at La Molina, eastern Spanish Pyrenees during the 1996 winter. Based on an acoustic principle, it consiste of a miniature microphone located at the base of an aluminium pole of a Variable length (depending on the average height of the snow accumulated in a season). While snowdrifting occurs and the pole is exposed to the flux (wind + snow particles), the snow grains impact on the pole and the sound produced by these collisions is recorded as an electrical signal. 30 m away from the snowdrifting detector, there is an anemometric station. The comparison of both records allows determination of thresholds and deposit wind velocities. In addition, this gauge allows users to know, during a wind episode, the exact amount of time during which snowdrifting occurs without being in the field. The interpretation of the values obtained using the acoustic detector is not yet an easy subject to discuss. We slill do not know what the drift-density equivalents for tile recorded noise levels are. However, these are only preliminary results and we expect to complete the calibration of the gauge during the coming months.

scholarly journals Drifting-snow acoustic detector: experimental tests in La Molina, Spanish Pyrenees

1998 ◽  
Vol 26 ◽  
pp. 221-224 ◽  
Author(s):  
D. Font ◽  
F. Naaim-Bouvet ◽  
M. Roussel
Keyword(s):  
Experimental Tests ◽  
Electrical Signal ◽  
Average Height ◽  
Acoustic Detector ◽  
Drifting Snow ◽  
Spanish Pyrenees ◽  
Wind Velocities ◽  
Drift Density ◽  
Exact Amount

A new gauge to detect drifting snow has been tested at an experimental site at La Molina, eastern Spanish Pyrenees during the 1996 winter.Based on an acoustic principle, it consiste of a miniature microphone located at the base of an aluminium pole of a Variable length (depending on the average height of the snow accumulated in a season). While snowdrifting occurs and the pole is exposed to the flux (wind + snow particles), the snow grains impact on the pole and the sound produced by these collisions is recorded as an electrical signal.30 m away from the snowdrifting detector, there is an anemometric station. The comparison of both records allows determination of thresholds and deposit wind velocities. In addition, this gauge allows users to know, during a wind episode, the exact amount of time during which snowdrifting occurs without being in the field. The interpretation of the values obtained using the acoustic detector is not yet an easy subject to discuss. We slill do not know what the drift-density equivalents for tile recorded noise levels are. However, these are only preliminary results and we expect to complete the calibration of the gauge during the coming months.

scholarly journals The Effect of Process Parameters in Helical Rolling of Balls on the Quality of Products and the Forming Process

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2125 ◽  
Author(s):  
Janusz Tomczak ◽  
Zbigniew Pater ◽  
Tomasz Bulzak
Keyword(s):  
Metal Flow ◽  
Experimental Tests ◽  
Rolling Process ◽  
Helical Rolling ◽  
Forming Process ◽  
University Of Technology ◽  
Quality Of Products ◽  
Skew Rolling

This paper presents selected numerical and experimental results of a skew rolling process for producing balls using helical tools. The study investigates the effect of the billet’s initial temperature on the quality of produced balls and the rolling process itself. In addition, the effect of billet diameter on the quality of produced balls is investigated. Experimental tests were performed using a helical rolling mill available at the Lublin University of Technology. The experiments consisted of rolling 40 mm diameter balls with the use of two helical tools. To determine optimal rolling parameters ensuring the highest quality of produced balls, numerical modelling was performed using the finite element method in the Forge software. The numerical analysis involved the determination of metal flow kinematics, temperature and damage criterion distributions, as well as the measurement of variations in the force parameters. The results demonstrate that the highest quality balls are produced from billet preheated to approximately 1000 °C.

Mechanical Behaviour of CoCrMo Alloy with Si Content

2015 ◽  
Vol 754-755 ◽  
pp. 1017-1022 ◽  
Author(s):  
Petrică Vizureanu ◽  
Mirabela Georgiana Minciună ◽  
Dragoş Cristian Achiţei ◽  
Andrei Victor Sandu ◽  
Kamarudin Hussin
Keyword(s):  
Tensile Strength ◽  
Chemical Composition ◽  
Testing Machine ◽  
Base Material ◽  
Optical Emission ◽  
Experimental Tests ◽  
Optical Emission Spectrometry ◽  
Emission Spectrometry ◽  
Standard Samples

.The paper present aspects about the obtaining of non-precious dental alloys (type CoCrMo and CoCrMoSi7), the determination of chemical composition by optical emission spectrometry and the experimental tests for determining the tensile strength, made on standard plate samples. The base material used in experiments was a commercial alloy, from CoCrMo system, which belongs to the class of dental non-precious alloys, intended to medical applications. The obtaining of studied alloy was made on arc re-melting installation, under vacuum, type MRF ABJ 900. The process followed to realize a rapid melting, with a maximum admissible current intensity. The samples for tests were obtained by casting in an electric arc furnace, under vacuum, in optimal conditions for melting and solidification and processing by electro-erosion, to eliminate all the disturbing factors which come by processing conditions for the samples. The determination of chemical composition for cobalt based alloys, by optical emission spectrometry, was made on SpectromaxX equipment with spark. The electrical discharge is made with the elimination of an energy quantity, fact which determine plasma forming and light issue. Tensile tests for standard samples, made from cobalt based alloy, was made on Instron 3382 testing machine, and assisted by computer. The obtained results are: elongation, elasticity modulus, tensile strength and offer complete information about the analyzed mechanical properties. For the certitude of obtained experimental results, the tests were made on samples with specific dimensions according ISO 6892-1:2009(E) standard, both for the tensile strength, and also machine operation.

DETERMINATION OF DRAG AND LIFT RELATED COEFFICIENTS OF AN AUV USING COMPUTATIONAL AND EXPERIMENTAL FLUID DYNAMICS METHODS

2021 ◽  
Vol 162 (A2) ◽  
Author(s):  
E Javanmard ◽  
Sh Mansoorzadeh ◽  
A Pishevar ◽  
J A Mehr
Keyword(s):  
Fluid Dynamics ◽  
Autonomous Underwater Vehicle ◽  
Experimental Tests ◽  
Hydrodynamic Coefficients ◽  
Experimental Fluid Dynamics ◽  
Computational Fluid Dynamics Cfd ◽  
Drag And Lift ◽  
Control Surfaces ◽  
Experimental Fluid

Determination of hydrodynamic coefficients is a vital part of predicting the dynamic behavior of an Autonomous Underwater Vehicle (AUV). The aim of the present study was to determine the drag and lift related hydrodynamic coefficients of a research AUV, using Computational and Experimental Fluid Dynamics methods. Experimental tests were carried out at AUV speed of 1.5 m s-1 for two general cases: I. AUV without control surfaces (Hull) at various angles of attack in order to calculate Hull related hydrodynamic coefficients and II. AUV with control surfaces at zero angle of attack but in different stern angles to calculate hydrodynamic coefficients related to control surfaces. All the experiments carried out in a towing tank were also simulated by a commercial computational fluid dynamics (CFD) code. The hydrodynamic coefficients obtained from the numerical simulations were in close agreement with those obtained from the experiments.

scholarly journals Determination of ASI and THIV parameters based on the results of experimental and numerical research in relation to EU standards

2021 ◽  
Vol 338 ◽  
pp. 01025
Author(s):  
Michał Stopel
Keyword(s):  
Experimental Tests ◽  
Severity Index ◽  
Point Of View ◽  
The Finite Element Method ◽  
Safety Level ◽  
The Road ◽  
Road Sign ◽  
Numerical Research ◽  
Python Programming

Determining the values of ASI (Acceleration Severity Index) and THIV (Theoretical Head Impact Velocity) parameters during tests allows you to assign an appropriate class for a given type of object to determine the safety level and to give the CE marking. The paper presents the methodology for determining these parameters based on the EN 1317-1 and EN 12767 standards. The paper also presents a tool created with the use of the Python programming language, which, based on the results of experimental tests or the results of numerical calculations, allows to determine the ASI and THIV values. The values of key parameters from the point of view of normative tests were calculated based on the results of experimental tests of the road sign supporting mast and numerical analysis carried out for the same case using the Finite Element Method and LS-Dyna software, following the EN 12767 standard.

Alberta bolide of June 1, 1982: interpretation of photographic and seismic records

1989 ◽  
Vol 26 (7) ◽  
pp. 1350-1355 ◽  
Author(s):  
G. L. Cumming
Keyword(s):  
Horizontal Plane ◽  
National Research Council ◽  
Average Height ◽  
Apparent Velocity ◽  
Zero Curvature ◽  
Seismic Recording ◽  
Seismic Records ◽  
Cold Lake ◽  
Front Curvature

Passage of a bright bolide northeast of Edmonton near midnight on the evening of June 1, 1982, was recorded both photographically by three cameras of the Meteorite Observation and Recovery Project of the National Research Council of Canada and by seismic recording stations at Edmonton and Cold Lake. The photographic data indicate a path towards the northwest at an average height of about 80 km and an average speed of 28 km/s. The Cold Lake data make possible the determination of direction and velocity of approach of the sound wave as well as wave-front curvature in the horizontal plane. The data indicate an essentially zero curvature and a speed across the array of 337.8 m/s for the sound arrival.Wave-front curvature indicates a line source, being the nearly cylindrical shock wave from the hypervelocity bolide. Directions of approach at both Cold Lake and Edmonton, however, seem to indicate a direction more consistent with the end of the brightest segment of the meteor photograph.The discrepancy is not resolved at present, nor is the very slow apparent velocity towards both Cold Lake and Edmonton as derived from the traveltimes to each of the seismic stations.

The Fictitious Radius as a Tool for Fatigue Life Estimation of Notched Elements

2012 ◽  
Vol 726 ◽  
pp. 27-32 ◽  
Author(s):  
Grzegorz Robak ◽  
Marcel Szymaniec ◽  
Tadeusz Łagoda
Keyword(s):  
Fatigue Life ◽  
Notch Root ◽  
Experimental Tests ◽  
Life Estimation ◽  
Fatigue Life Estimation

In this paper, the fictitious radius - according to Neuber’s method for determination of stresses at the notch root was used. Next, the fatigue lives of elements of the ring notches were calculated, and then compared with results of experimental tests of S235JR steel samples. However, the obtained fatigue lives did not bring satisfactory results. It has been demonstrated that the fictitious radius strongly depends on the expected fatigue life

Laboratory studies of wind–wave interactions

1968 ◽  
Vol 34 (1) ◽  
pp. 91-111 ◽  
Author(s):  
Jin Wu
Keyword(s):  
Surface Roughness ◽  
Wind Stress ◽  
Water Surface ◽  
Wind Wave ◽  
Wave Drag ◽  
Average Height ◽  
Drift Current ◽  
Stress Coefficient ◽  
Wide Range ◽  
Wind Velocities

The present study consists of wind profile surveys, drift current measurements and water surface observations for a wide range of wind velocities in a wind–wave tank. It is confirmed that the velocity distribution essentially follows the logarithmic law near the water surface and the velocity-defect law toward the outer edge of the boundary layer. The wind stresses and surface roughnesses calculated from these distributions are divided into two groups separated by the occurrence of the wave-breaking phenomenon. For low wind velocities the surface roughness is dictated by ripples, and the wind-stress coefficient varies with U0−½, where U0 is the free-stream wind velocity. The surface roughness is proportional to the average height of the basic gravity wave at higher wind velocities; the stress coefficient is then proportional to U0. In addition, it is found that Charnock's expression (k ∝ u*2/g) holds only at high wind velocities, and that the constant of proportionality determined from the present experiment correlates very well with field observations. A new technique, involving the use of various-sized surface floats to determine the drift current gradient and the surface drift current, has been developed. A good agreement is shown between the gradients obtained from the measured currents and those determined from the wind stresses. Finally, the wind-stress coefficient is shown to be larger than the friction coefficient for turbulent flow along a solid rough surface; the difference is shown to be the wave drag of the wind over the water surface.

AN EVALUATION OF SEVERAL METHODS OF ESTIMATING SITE INDEX OF IMMATURE STANDS

1952 ◽  
Vol 28 (3) ◽  
pp. 63-74 ◽  
Author(s):  
John W. Ker
Keyword(s):  
Basal Area ◽  
Site Index ◽  
Site Quality ◽  
Average Height ◽  
Office Procedure ◽  
Minimum Sample ◽  
A Site ◽  
The University ◽  
Site Classes

The use of dominant heights for the estimation of site index is compared with the use of the average of dominant and codominant heights. Data collected on the University Research Forest are presented to illustrate the variability in tree heights and diameters within the two upper crown classes in well-stocked stands of immature Douglas fir.HeightIt is shown that the use of dominant heights reduces considerably the number of measurements required for a site index determination of given accuracy. Minimum sample sizes are given for three limits of accuracy for use in different site qualities. A general field and office procedure is outlined for the determination of minimum sample size in stands other than those described.DiameterThe use of diameter in site determination is discussed. Site indices based on the height of the tree of mean diameter, the height of the tree of mean basal area, and mean height are compared.ConclusionsQuick estimates of site quality can best be obtained by the measurement of total height of sample dominant trees, selected at random. For this purpose, tables are presented which list the average height of dominant trees by age and site classes for use in stands of Douglas fir, and western hemlock, respectively.

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