The physics remote laboratory: Implementation of an experiment on Standing Waves

Author(s):  
Thiago Costa Caetano ◽  
Mikael Frank Rezende Júnior ◽  
Agenor Pina da Silva ◽  
Camila Cardoso Moreira

Abstract There always have been some hurdles when it comes to the adequate use of didactical experimental activities in science education, such as the lack of proper training, insufficient time, and inadequate infrastructure. At this very moment, the pandemic has taught us that there may be also circumstances in which the traditional laboratory and the traditional activities are just not possible, thus online operable experiments might constitute a viable alternative for the practical lessons in higher education. In this paper, we discuss the development and the implementation of a remote-controlled didactical experiment on Standing Waves largely used in the physics basic program offered to the engineering courses. The development has combined applied knowledge from different areas, i.e. electric and electronics engineering, and computer science. In order to ascertain the experiment consistency, we have gathered data from the wave propagation speed and from the corresponding tension applied to the string and performed a χ-square linear fit in order to determine the correlation between the logarithm of both parameters. The experiment was successfully implemented and has been accessed by hundreds of different users from more than 30 different countries ever since. It has also been largely employed in practical activities at the university and has shown no significant signs of instability. It exhibited a total latency time inferior to 0.8 seconds on average and the results drawn from data it provides have shown to be accurate, within less than 0.8% of deviation with respect to the theoretical results.

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Edgar V.M. Carrasco ◽  
Rejane C. Alves ◽  
Mônica A. Smits ◽  
Vinnicius D. Pizzol ◽  
Ana Lucia C. Oliveira ◽  
...  

Abstract The non-destructive wave propagation technique is used to estimate the wood’s modulus of elasticity. The propagation speed of ultrasonic waves is influenced by some factors, among them: the type of transducer used in the test, the form of coupling and the sensitivity of the transducers. The objective of the study was to evaluate the influence of the contact pressure of the transducers on the ultrasonic speed. Ninety-eight tests were carried out on specimens of the species Eucalyptus grandis, with dimensions of 120 × 120 × 50 mm. The calibration of the pressure exerted by the transducer was controlled by a pressure gauge using a previously calibrated load cell. The robust statistical analysis allowed to validate the experimental results and to obtain consistent conclusions. The results showed that the wave propagation speed is not influenced by the pressure exerted by the transducer.


2020 ◽  
Vol 128 (1) ◽  
pp. 98
Author(s):  
С.А. Двинин ◽  
Д.К. Солихов ◽  
Ш.С. Нурулхаков

The evolution of a perturbation from a local source for Mandel'shtam-Brillouin scattering in a plasma layer with unlimited length is calculated. Perturbation over time in this case can either leave the scattering region through one of the two boundaries, or propagate along the layer at a speed below sound wave propagation speed, with an exponential growth, or a fall in perturbation amplitude. In the particular case of strictly backward scattering (the scattering angle is π), this propagation velocity is zero. The paper calculates the threshold instability fields and the instability increments, taking into account both convective losses and collisional attenuation of waves. It is shown that the instability threshold for scattering at an arbitrary angle can be lower than for strictly backwards scattering and when the threshold is exceeded by the intensity of the pump wave; the scattering increment at an angle can also be higher than the increment for backscattering. When the threshold is greatly exceeded, the convective losses can be neglected, and the largest increment is observed for backward scattering.


Author(s):  
Amin Moslemi Petrudi ◽  
Masoud Rahmani

In this research, the discrete element method has been used to analyze wave propagation and to investigate the factors affecting wave reduction in granular soils. The method of discrete elements is important because of the possibility of preparing completely similar specimens and examining the effect of changes in a certain parameter on the Behavior of the specimens. This method also provides an understanding of the changes that have occurred at the micro-scale of granular materials that are not achievable with other laboratory and numerical methods. To model the specimens, a set of disks with specific granulation has been used for two-dimensional studies. PFC 2D software has been used to perform simulations and related analyzes such as interparticle force. The DEM code in MATLAB is used to check the wave depreciation. In this research, the optimization process was performed using experimental data and the Taguchi method using the DEM method. The results of this study show that there is a direct relationship between the number of particle set contacts and the wave propagation speed. Also, material properties such as particle density are the most important parameters affecting wave velocity. The results of the method (DEM) are done with PFC 2D software and a comparison between the results of this method with the solution methods used by other researchers is shown to be a good match.


2021 ◽  
Author(s):  
Marija Raković ◽  

The paper deals with the observation of the specifics of online teaching of lexicology and syntax of the Serbian language at the Faculty of Philology of students studying a foreign language. The aim is to notice possibilities of realization of online teaching. The research was conducted on the basis of the implementation of the teaching process in the subject Serbian language 2 (lexicology and syntax) and a survey of students on the advantages and disadvantages of online teaching. The analysis showed that online teaching provides shortcomings in the form of insufficient time for the teacher to deal in more detail with student ambiguities, but also provides numerous opportunities for progress in education – mostly in terms of student time organization and uninterrupted questioning, which is not always the case. Based on the obtained results, we will try to give methodological implications for teaching practice, which concern the possibility of improving online teaching of the Serbian language at the university level.


Author(s):  
Kelley C. Stewart ◽  
Rahul Kumar ◽  
John J. Charonko ◽  
Pavlos P. Vlachos ◽  
William C. Little

Numerous studies have shown that cardiac diastolic dysfunction and diastolic filling play a critical role in dictating overall cardiac health and demonstrated that the filling wave propagation speed is a significant index of the severity of diastolic dysfunction [1, 2]. However, the governing flow physics underlying the relationship between propagation speed and diastolic dysfunction are poorly understood. More importantly, currently there is no reliable metric to allow clinicians the ability to diagnose cardiac dysfunction on the basis of the wave filling speed.


2016 ◽  
Vol 140 (4) ◽  
pp. 3002-3002
Author(s):  
Gyungmin Toh ◽  
Dongki Min ◽  
Jaehong Lee ◽  
Junhong Park

1996 ◽  
Vol 307 ◽  
pp. 191-229 ◽  
Author(s):  
Jeng-Jong Lee ◽  
Chiang C. Mei

A theory is described for the nonlinear waves on the surface of a thin film flowing down an inclined plane. Attention is focused on stationary waves of finite amplitude and long wavelength at high Reynolds numbers and moderate Weber numbers. Based on asymptotic equations accurate to the second order in the depth-to-wavelength ratio, a third-order dynamical system is obtained after changing to the frame of reference moving at the wave propagation speed. By examining the fixed-point stability of the dynamical system, parametric regimes of heteroclinc orbits and Hopf bifurcations are delineated. Extensive numerical experiments guided by the linear analyses reveal a variety of bifurcation scenarios as the phase speed deviates from the Hopf-bifurcation thresholds. These include homoclinic bifurcations which lead to homoclinic orbits corresponding to well separated solitary waves with one or several humps, some of which occur after passing through chaotic zones generated by period-doublings. There are also cases where chaos is the ultimate state following cascades of period-doublings, as well as cases where only limit cycles prevail. The dependence of bifurcation scenarios on the inclination angle, and Weber and Reynolds numbers is summarized.


2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Robert P. Czachor

The interaction of vibratory traveling waves in rotating and stationary axisymmetric components is examined. In the most general case, a resonance can occur when the wave propagation speed in a first structure is equal in magnitude and direction to the rotational velocity of an adjacent structure. When a backward wave in a rotor appears stationary, a major resonance, as discussed in Wilfred Campbell's classic paper (Campbell, W., 1924, “The Protection of Steam Turbine Disc Wheels from Axial Vibrations,” Trans ASME, 46, pp. 31–160), results. A related resonance has been observed when the wave propagation speed in the stator is equal to the physical speed of the adjacent rotor. A third mechanism is derived for resonance between a wave in rotor 1 and a co- or counter-rotating rotor 2. Description of a component test which demonstrated this final phenomenon is provided.


2002 ◽  
Vol 451 ◽  
pp. 109-144 ◽  
Author(s):  
KEVIN G. LAMB

The formation of solitary internal waves with trapped cores via shoaling is investigated numerically. For density fields for which the buoyancy frequency increases monotonically towards the surface, sufficiently large solitary waves break as they shoal and form solitary-like waves with trapped fluid cores. Properties of large-amplitude waves are shown to be sensitive to the near-surface stratification. For the monotonic stratifications considered, waves with open streamlines are limited in amplitude by the breaking limit (maximum horizontal velocity equals wave propagation speed). When an exponential density stratification is modified to include a thin surface mixed layer, wave amplitudes are limited by the conjugate flow limit, in which case waves become long and horizontally uniform in the centre. The maximum horizontal velocity in the limiting wave is much less than the wave's propagation speed and as a consequence, waves with trapped cores are not formed in the presence of the surface mixed layer.


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