scholarly journals Damped Oscillations – A smartphone approach

2021 ◽  
Author(s):  
Marciano Santamaría ◽  
Evgeni Cruz de Gracia ◽  
Lucio Dorneles
Keyword(s):  
Cross Section ◽  
Significant Variation ◽  
Oscillation Amplitude ◽  
Angular Frequency ◽  
Reliable Tool ◽  
Damped Oscillations ◽  
Cross Section Area ◽  
Section Area ◽  
Geometric Factors ◽  
The Cross

The study of the influence of geometric factors on an oscillating pendulum under various damping conditions is reported. Different cross-section areas perpendicular to the motion of the pendulum mass were studied. A smartphone was used as a pendulum and at the same time as a data recorder. Results show that the smartphone is an effective and reliable tool to be used when performing educational activities, and at the same time it presents students with a variety of ways for learning new content and physical concepts. It offers the opportunity to carry out experiments in the classroom, in the laboratory, or at home. In this way, the increment in the cross-section area slightly increases the damping coefficient, and rapidly decreases the oscillation amplitude as time passes. Additionally, the time necessary to decrease the amplitude by half is inversely proportional to the cross-section area of the pendulum. As expected, no significant variation in the period nor the angular frequency were found, due to the air-pendulum drag properties and to the slow pendulum speed.

scholarly journals Damped Oscillations – A smartphone approach

2021 ◽  
Author(s):  
Marciano Santamaría ◽  
Evgeni Cruz de Gracia ◽  
Lucio Dorneles
Keyword(s):  
Cross Section ◽  
Significant Variation ◽  
Oscillation Amplitude ◽  
Angular Frequency ◽  
Reliable Tool ◽  
Damped Oscillations ◽  
Cross Section Area ◽  
Section Area ◽  
Geometric Factors ◽  
The Cross

The study of the influence of geometric factors on an oscillating pendulum under various damping conditions is reported. Different cross-section areas perpendicular to the motion of the pendulum mass were studied. A smartphone was used as a pendulum and at the same time as a data recorder. Results show that the smartphone is an effective and reliable tool to be used when performing educational activities, and at the same time it presents students with a variety of ways for learning new content and physical concepts. It offers the opportunity to carry out experiments in the classroom, in the laboratory, or at home. In this way, the increment in the cross-section area slightly increases the damping coefficient, and rapidly decreases the oscillation amplitude as time passes. Additionally, the time necessary to decrease the amplitude by half is inversely proportional to the cross-section area of the pendulum. As expected, no significant variation in the period nor the angular frequency were found, due to the air-pendulum drag properties and to the slow pendulum speed.

Thermoacoustic Shape Optimization of a Subsonic Nozzle

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Alexis Giauque ◽  
Maxime Huet ◽  
Franck Clero ◽  
Sébastien Ducruix ◽  
Franck Richecoeur
Keyword(s):  
Acoustic Emission ◽  
Cross Section ◽  
Source Term ◽  
Combustion Noise ◽  
Noise Emission ◽  
Cross Section Area ◽  
Section Area ◽  
The Cross ◽  
Nozzle Flows ◽  
Subsonic Nozzle

Indirect combustion noise originates from the acceleration of nonuniform temperature or high vorticity regions when convected through a nozzle or a turbine. In a recent contribution (Giauque et al., 2012, “Analytical Analysis of Indirect Combustion Noise in Subcritical Nozzles,” ASME J. Eng. Gas Turbies Power, 134(11), p. 111202) the authors have presented an analytical thermoacoustic model providing the indirect combustion noise generated by a subcritical nozzle when forced with entropy waves. This model explicitly takes into account the effect of the local changes in the cross-section area along the configuration of interest. In this article, the authors introduce this model into an optimization procedure in order to minimize or maximize the thermoacoustic noise emitted by arbitrarily shaped nozzles operating under subsonic conditions. Each component of the complete algorithm is described in detail. The evolution of the cross-section changes are introduced using Bezier's splines, which provide the necessary freedom to actually achieve arbitrary shapes. Bezier's polar coordinates constitute the parameters defining the geometry of a given individual nozzle. Starting from a population of nozzles of random shapes, it is shown that a specifically designed genetic optimization algorithm coupled with the analytical model converges at will toward a quieter or noisier population. As already described by Bloy (Bloy, 1979, “The Pressure Waves Produced by the Convection of Temperature Disturbances in High Subsonic Nozzle Flows,” J. Fluid Mech., 94(3), pp. 465–475), the results therefore confirm the significant dependence of the indirect combustion noise with respect to the shape of the nozzle, even when the operating regime is kept constant. It appears that the quietest nozzle profile evolves almost linearly along its converging and diverging sections, leading to a square evolution of the cross-section area. Providing insight into the underlying physical reason leading to the difference in the noise emission between two extreme individuals, the integral value of the source term of the equation describing the behavior of the acoustic pressure of the nozzle is considered. It is shown that its evolution with the frequency can be related to the global acoustic emission. Strong evidence suggest that the noise emission increases as the source term in the converging and diverging parts less compensate each other. The main result of this article is the definition and proposition of an acoustic emission factor, which can be used as a surrogate to the complex determination of the exact acoustic levels in the nozzle for the thermoacoustic shape optimization of nozzle flows. This acoustic emission factor, which is much faster to compute, only involves the knowledge of the evolution of the cross-section area and the inlet thermodynamic and velocity characteristics to be computed.

An Analytical Method of Analyzing the Heat Conduction for the Unequal Cross-Section Straight Fin

2013 ◽  
Vol 365-366 ◽  
pp. 1211-1216
Author(s):  
Fan Zhang ◽  
Peng Yun Song
Keyword(s):  
Heat Conduction ◽  
Cross Section ◽  
Analytical Method ◽  
Thermal Analyses ◽  
Cross Sectional ◽  
Cross Section Area ◽  
Section Area ◽  
Calculation Results ◽  
The Cross ◽  
Analytical Expressions

The cross-section area of straight fin is often considered to be equal in the thermal analyses of straight fin, but sometimes it is unequalin actual situation. Taking a straight fin with two unequal cross-sectional areas as an example,an analytical method of heat conduction for unequal section straight fin is presented. The analytical expressions of temperature field and heat dissipating capacity about the fin,which has a smaller cross-section area near the fin base and a larger one, is obtained respectively. The calculation results of the unequal cross-section are fully consistent with the equal area one, so the method is proved right. The results show that the larger the cross section areanear the base,the better is the heat transfer, and the temperature at the base with larger cross-section area is lower than that with smaller cross-section area when the amount of heat is fixed.

scholarly journals Evaluation of the effect of cooling strategies on recovery after surgical intervention

2019 ◽  
Vol 5 (1) ◽  
pp. e000527 ◽  
Author(s):  
Daniel Engelhard ◽  
Pierre Hofer ◽  
Simon Annaheim
Keyword(s):  
Cross Section ◽  
Cruciate Ligament ◽  
Control Group ◽  
Postoperative Phase ◽  
Cooling Strategies ◽  
Cross Section Area ◽  
Section Area ◽  
Days Of Therapy ◽  
The Cross ◽  
Cold Pack

IntroductionDifferent cooling strategies exist for emergency treatments immediately after sports trauma or after surgery. The aim of this study was to investigate the effects of three cooling regimen during the immediate postoperative phase as well as in the rehabilitation phase.Methods36 patients undergoing anterior cruciate ligament reconstruction received either no cooling (control-group, Con, N=12), were cooled with a menthol-containing cooling bandage (Mtl, N=12) or cooled with an ice containing cold pack (CP, N=12). During a 12-week physiotherapy treatment the cross section of the vastus medialis muscle was examined (day—1; 30; 60; 90) and painkiller consumption was documented.ResultsA significant reduction in the cross section area 30 days after surgery was observed in CP and Con (Mtl: −3.2±1.7%, p=0.14, CP: −8.8±4.3%, p<0.01, Con: −7.2±8.1%, p<0.05). After 90 days of therapy, a significant increase in muscle cross section area was observed in Mtl (Mtl: 4.6%±6.1%, p<0.05, CP: 1.9%± 8.1%, p=0.29, Con: 3.3%±9.4%, p=0.31). The absolute painkiller consumption was lower for Mtl (25.5±3.7 tablets) than for CP (39.5±6.9 tablets) or Con (34.8±4.2 tablets).ConclusionWe observed a beneficial effect of cooling by a menthol-containing bandage during the rehabilitation phase. Reduction of muscle cross section within 30 days after surgery was prevented which highly contributed to rehabilitation success after 90 days of therapy. Painkiller consumption was reduced with Mtl.

179 CORPUS LUTEUM DEVELOPMENT AFTER FOLLICLE ASPIRATION IS RELATED TO CHARACTERISTICS OF THE ASPIRATED FOLLICLE IN DAIRY COWS

2013 ◽  
Vol 25 (1) ◽  
pp. 238
Author(s):  
A. Vernunft ◽  
J. M. Weitzel ◽  
T. Viergutz
Keyword(s):  
Corpus Luteum ◽  
Cross Section ◽  
Quality Parameter ◽  
Preovulatory Follicle ◽  
Dominant Follicle ◽  
Cross Section Area ◽  
Section Area ◽  
Luteal Tissue ◽  
The Cross ◽  
Follicle Aspiration

The aim of this study was to investigate whether morphology or function of a corpus luteum (CL), which developed after an aspiration of a preovulatory follicle, is related to follicular characteristics such as size or steroid content. If so, CL morphology or function could be used as a retrospective quality parameter for the aspirated follicle or the follicular characteristics as a prospective parameter for the quality of the developing CL. Therefore, 44 aspiration sessions were performed using 18 cows between 26 and 121 days after parturition during the first lactation. Heat was induced in mid-dioestrus with Cloprostenol. A GnRH analogon (Depherelin) were administrated 54 h later. The dominant follicle was aspirated 21 h after administration of the GnRH analogue. The diameter of the dominant follicle at aspiration and the cross-section area of the resulting luteal tissue 14 days later were measured by ultrasound. Concentrations of progesterone (P4) and 17-β-oestradiol (E2) in blood and follicular fluid (FF) were determined by H3-RIA. A CL development occurred in 82% of aspiration sessions after aspirating the dominant follicles. The interval of time between parturition and follicle aspiration did not affect variables investigated. As expected, cross-section area of the luteal tissue was positively correlated with plasma P4 concentration on Day 14 after follicle aspiration (r = 0.54; P < 0.01). The diameter of the aspirated follicle was positively correlated with the plasma P4 concentration on Day 14 after follicle aspiration (r = 0.52; P = 0.02), but the diameter was not correlated with the cross-section. Comparing the FF of follicles that originated a CL after aspiration with follicles that did not, both types had comparable P4 concentrations (578 ± 79 ng mL–1 v. 398 ± 84 ng mL–1; P = 0.2), but the former type presented higher E2 concentrations (206 ± 23 ng mL–1 v. 64 ± 29 ng mL–1, P < 0.01) compared with the latter. The P4 concentrations in FF of follicles that originated a CL after aspiration were positively related to cross-section area of the CL (r = 0.48; P = 0.04), but neither P4 nor E2 concentrations in the FF of preovulatory follicles could be used as a predictor for the plasma P4 concentration at day 14. In conclusion, CL development after follicle aspiration can be used as a retrospective quality parameter of aspirated dominant follicles. Preovulatory follicle diameter as well as cross-section area of the luteal tissue could be used prospectively to identify cows with high plasma P4 levels, and this may help to identify suitable recipients for embryo transfer. This study was supported by the German Research Foundation (DFG WE 2458/7-2).

Thermoacoustic Shape Optimization of a Subsonic Nozzle

2013 ◽  
Author(s):  
Alexis Giauque ◽  
Maxime Huet ◽  
Franck Clero ◽  
Sébastien Ducruix ◽  
Franck Richecoeur
Keyword(s):  
Acoustic Emission ◽  
Shape Optimization ◽  
Cross Section ◽  
Emission Factor ◽  
Source Term ◽  
Combustion Noise ◽  
Noise Emission ◽  
Cross Section Area ◽  
Section Area ◽  
The Cross

Indirect combustion noise originates from the acceleration of non-uniform temperature or high vorticity regions when convected through a nozzle or a turbine. In an recent contribution (Giauque et al., JEGTP, 2012), the authors have presented an analytical thermoacoustic model providing the indirect combustion noise generated by a subcritical nozzle when forced with entropy waves. This model explicitly takes into account the effect of the local changes in the cross-section area along the configuration of interest. In this article, the authors introduce this model into an optimization procedure in order to minimize or maximize the thermoacoustic noise emitted by arbitrary shaped nozzles operating under subsonic conditions. Each component of the complete algorithm is described in details. The evolution of the cross-section changes are introduced using Beziers splines which provide the necessary freedom to actually achieve arbitrary shapes. Beziers poles coordinates constitute the parameters defining the geometry of a given individual nozzle. Starting from a population of nozzles of random shapes, it is shown that a specifically designed genetic optimization algorithm coupled with the analytical model converges at will toward a quieter or noisier population. As already described by Bloy (JFM, 1979), results therefore confirm the significant dependence of the indirect combustion noise with respect to the shape of the nozzle, even when the operating regime is kept constant. It appears that the quietest nozzle profile evolves almost linearly along its converging and diverging sections leading to a square evolution of the cross-section area. Providing insight in the underlying physical reason leading to the difference in noise emission between two extreme individuals, the integral value of the source term of the equation describing the behavior of the acoustic pressure of the nozzle is considered. It is shown that its evolution with the frequency can be related to the global acoustic emission. Strong evidence suggest that the noise emission increases as the source term in the converging and diverging parts less compensate each other. The main result of this article is the definition and proposition of an Acoustic Emission Factor which can be used as a surrogate to the complex determination of the exact acoustic levels in the nozzle for the thermoacoustic shape optimization of nozzle flows. This Acoustic Emission Factor, much faster to compute, only involves the knowledge of the evolution of the cross-section area as well as the inlet thermodynamic and velocity characteristics to be computed.

scholarly journals Numerical simulation of cutting layer in internal corners milling

Mechanik ◽  
2019 ◽  
Vol 92 (7) ◽  
pp. 412-414
Author(s):  
Jan Burek ◽  
Rafał Flejszar ◽  
Barbara Jamuła
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Cross Section ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Cross Section Area ◽  
Section Area ◽  
The Cross ◽  
The Stability

The analytical and numerical model of the cross-section of the machined layer in the process of milling of concave rounding is presented. Simulation tests were carried out to determine the cross-sectional area of the cutting layer. A strategy has been developed that allows to increase the stability of the cross-section area of the cutting layer when the mill enters the inner corner area.

Comparative Study of Steel Beam Column Connection under Cyclic Loading

2016 ◽  
Vol 857 ◽  
pp. 53-58
Author(s):  
S. Anisha ◽  
Dhanya Krishnan
Keyword(s):  
Cross Section ◽  
Plastic Hinge ◽  
Steel Beam ◽  
Cross Sectional ◽  
Reduced Beam Section ◽  
Cross Section Area ◽  
Section Area ◽  
Beam Section ◽  
The Cross ◽  
Stress And Deformation

A structure is an assembly of various elements or components which are fastened together through some type of connections. Steel beam column connection may fail due to large earth quake. Plastic hinge formation is the main failure of a steel beam column connection. There are two methods for improving the steel beam column connection (i) connection reinforcement/strengthening (ii) beam weakening by reducing the cross-sectional area of the beam at a certain distance from the connection. When reducing the cross section area plastic hinge is formed away from column face. The main objective of this study is to compare reduced beam section (RBS) and reduced web section (RWS) pattern and find out the location of plastic hinge. For steel beam column plastic hinge is located near column. When reducing the cross section area the location of plastic hinge will shift from the column. Aim of this project is to locate the position of plastic hinge apart from column face, and also evaluate the stress and deformation.

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