cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.14325337.v1
title: Global/Local Non-Intrusive Crack Analysis Using Element Free Galerkin and Linear Galerkin Finite Volume Methods

description: Abstract Although various numerical methods are proposed to solve a wide range of problems so far, each has its own advantages and disadvantages. Therefore, it would be highly desirable to develop a computationally efficient combined approach, which makes use of their advantages and reduces their drawbacks. In this regard, a non-intrusive iterative global/local (IGL) algorithm is proposed to evaluate the structures with local discontinuity. Firstly, in each iteration, the entire continuum domain is solved using the Galerkin Finite Volume (GFV) method, which consumes light computational workload for predicting accurate results of linear structural response. Then, the Element Free Galerkin (EFG) meshless method is locally employed as an accurate but computationally expensive solver to cover the shortcomings of the GFV solver in the crack analysis. The specific form of Quasi-Newtonian and dynamic accelerators are adopted to increase the convergence rate in each computational increment. Finally, the proposed method's accuracy and speed are examined by computing stress intensity factors (SIFs) for several distinct 2D cracked models.
DOI: 10.6084/m9.figshare.14325325.v1
title: Buckling of Axially Compressed Cones with Imperfect Axial Length

description: Abstract The paper considers the effect of imperfect length on the buckling behavior of axially compressed mild steel truncated cone. Three types of initial geometric imperfections with different number of waves along the compressed edge are analyzed, and they are: (i) sinusoidal waves, (ii) triangular waves, and (iii) square waves. A validation of experimental data from previous study and further numerical calculations are provided in this paper. A good repeatability of experimental data was revealed through the test results with only 0% to 7% of error. Numerical simulations were carried out using ABAQUS FE code. It is shown that the buckling load of the cone is differently affected by the shape and amplitude of the imperfection. Apparently, the buckling loads of analyzed cones are less sensitive when imperfection shape is triangular as compared to other imperfection shapes. Furthermore, the effect of number of waves on buckling load of axially compressed cones was investigated for the above three cases. Results indicate that the influence of number of waves on the load carrying capacity of the cone is less significant.
DOI: 10.6084/m9.figshare.14325915.v1
title: An introduction to Landau's Theory of Fermi Liquids

description: Abstract We present an introduction to Landau's Theory of Fermi Liquids. We seek to highlight the paradigms established by Lev Landau in the 1950s, which influence the development of current research areas. In turn, we argue that it is possible to teach this theory in physics undergraduate courses, having a positive impact on the knowledge building of professionals specialized in areas such as Solid State and Strongly Correlated Electrons. The presentation is constructive, self-contained and aimed at Physics undergraduate and graduate students. As an example, we study wave propagation in a simplified two-dimensional Fermi liquid model. The output is related with one of Landau's best known results, the “zero sound” excitation.
DOI: 10.6084/m9.figshare.14325915
title: An introduction to Landau's Theory of Fermi Liquids

description: Abstract We present an introduction to Landau's Theory of Fermi Liquids. We seek to highlight the paradigms established by Lev Landau in the 1950s, which influence the development of current research areas. In turn, we argue that it is possible to teach this theory in physics undergraduate courses, having a positive impact on the knowledge building of professionals specialized in areas such as Solid State and Strongly Correlated Electrons. The presentation is constructive, self-contained and aimed at Physics undergraduate and graduate students. As an example, we study wave propagation in a simplified two-dimensional Fermi liquid model. The output is related with one of Landau's best known results, the “zero sound” excitation.
DOI: 10.6084/m9.figshare.14325903.v1
title: A zero cost methodology for the measurement of the rolling resistance in UAVs

description: Abstract Despite the fact that measurements of the rolling friction coefficient are important in several areas, the subject in general is not adequately addressed in high school or college. This situation deprives the student of the knowledge of the experimental resources used to measure the friction coefficient, in addition to compromising the understanding of the phenomenon. In addition, certain pairs of materials of interest to engineering are simply not found in the literature, as in the case of tires used in unmanned aerial vehicles (UAVs). In an attempt to fill both gaps, the present work presents a methodology for determining the rolling friction coefficient in UAVs. The method used is extremely simple, in terms of its implementation and of the theory used, but it is still interesting from a didactic point of view and due to the fact that its cost is practically zero, using only an inclined plane and measures of the distance covered by the UAV. The results show friction coefficient values depending on the vehicle's weight. The values obtained are discussed and suggestions for the future improvement of the experiment are presented.
DOI: 10.6084/m9.figshare.14325917
title: Flow Visualization using the Shadowgraph and Schlieren Optical Methods

description: Abstract The use of experiments is one of the most efficient ways to teach physics, since students become more motivated when fundamental theoretical concepts are associated with technological applications. The development of cars, aircraft and rockets, for example, requires detailed knowledge of the flow of fluids around and inside these vehicles. This article describes the fundamentals of geometric optics in heterogeneous media and presents the shadowgraph and schlieren optical techniques that are widely used in research centers, universities and companies in the study of aerodynamics and flows in general. These optical methods are based on the deflection of the light rays caused by variations in the flow density. The schlieren-Toepler method is discussed in detail, deriving equations for contrast, sensitivity and optical alignment. An implementation of the direct shadowgraph method for classroom use is demonstrated and, throughout the article, several images obtained by the described optical methods are presented.
DOI: 10.6084/m9.figshare.14325917.v1
title: Flow Visualization using the Shadowgraph and Schlieren Optical Methods

description: Abstract The use of experiments is one of the most efficient ways to teach physics, since students become more motivated when fundamental theoretical concepts are associated with technological applications. The development of cars, aircraft and rockets, for example, requires detailed knowledge of the flow of fluids around and inside these vehicles. This article describes the fundamentals of geometric optics in heterogeneous media and presents the shadowgraph and schlieren optical techniques that are widely used in research centers, universities and companies in the study of aerodynamics and flows in general. These optical methods are based on the deflection of the light rays caused by variations in the flow density. The schlieren-Toepler method is discussed in detail, deriving equations for contrast, sensitivity and optical alignment. An implementation of the direct shadowgraph method for classroom use is demonstrated and, throughout the article, several images obtained by the described optical methods are presented.
DOI: 10.6084/m9.figshare.14325921
title: Introduction to continuous photocounting effects on the quantized optical field

description: Abstract In this manuscript, we explore the effects of continuous measurements upon the quantized electromagnetic field through a series of simple examples. For this purpose, we consider the Srinivas-Davies model to describe the optical field dynamics probed continuously by a photodetector. Through the application of this continuous photodetection model to some specific situations, it is possible to cover some basic concepts of quantum mechanics such as the principle of superposition, the collapse of the wave function, the probabilistic character of the possible outcomes associated with projective measurements, as well as some advanced topics such as the description of open quantum systems, irreversible processes in quantum mechanics, decoherence and dissipation associated with non-unitary evolution of quantum systems. Besides, we also consider the important concept of entanglement between two electromagnetic fields and how it is affected by the photodetection process. This work aims to provide complementary material for undergraduate and graduate students interested in the effects of measuring devices acting on quantum systems.
DOI: 10.6084/m9.figshare.14325921.v1
title: Introduction to continuous photocounting effects on the quantized optical field

description: Abstract In this manuscript, we explore the effects of continuous measurements upon the quantized electromagnetic field through a series of simple examples. For this purpose, we consider the Srinivas-Davies model to describe the optical field dynamics probed continuously by a photodetector. Through the application of this continuous photodetection model to some specific situations, it is possible to cover some basic concepts of quantum mechanics such as the principle of superposition, the collapse of the wave function, the probabilistic character of the possible outcomes associated with projective measurements, as well as some advanced topics such as the description of open quantum systems, irreversible processes in quantum mechanics, decoherence and dissipation associated with non-unitary evolution of quantum systems. Besides, we also consider the important concept of entanglement between two electromagnetic fields and how it is affected by the photodetection process. This work aims to provide complementary material for undergraduate and graduate students interested in the effects of measuring devices acting on quantum systems.
DOI: 10.6084/m9.figshare.14325923.v1
title: Power Inverters: Theoretical concepts and experimental demonstration

description: Abstract Power inverters are electrical circuits capable of transforming direct current (DC) into alternating current (AC). Currently, due to the growing trend to replace combustion engines with electric motors and also for the production of residential solar electric power, power inverters are playing a fundamental role in mediating electricity generating sources with different types of loads, which include domestic applications, automotive and industrial. In this work, we intend to explore basic theoretical concepts on the operation of power inverters and demonstrate their principle of operation through simplified experiments. These experiments have an analytical character and can be introduced in undergraduate courses with specific practical subjects for students in physics or engineering courses.
DOI: 10.6084/m9.figshare.14325923
title: Power Inverters: Theoretical concepts and experimental demonstration

description: Abstract Power inverters are electrical circuits capable of transforming direct current (DC) into alternating current (AC). Currently, due to the growing trend to replace combustion engines with electric motors and also for the production of residential solar electric power, power inverters are playing a fundamental role in mediating electricity generating sources with different types of loads, which include domestic applications, automotive and industrial. In this work, we intend to explore basic theoretical concepts on the operation of power inverters and demonstrate their principle of operation through simplified experiments. These experiments have an analytical character and can be introduced in undergraduate courses with specific practical subjects for students in physics or engineering courses.
DOI: 10.6084/m9.figshare.14325924
title: Light interference: a correlation between Young's experiment and interference lithography

description: Abstract This work aims to relate Young's experiment with an experimental technique for periodic structures fabrication known as two-beam interference lithography. The relationship between the experiments was made in terms of intensity distribution, considering a vectorial approach, where the superposition of two plane waves was used as a starting point. Within the limits considered in Young's experiment, the results show that the intensity distribution of both experiments coincide. In addition, this study provides a broader discussion on light interference, particularly the use of this phenomenon in technological applications.
DOI: 10.6084/m9.figshare.14325924.v1
title: Light interference: a correlation between Young's experiment and interference lithography

description: Abstract This work aims to relate Young's experiment with an experimental technique for periodic structures fabrication known as two-beam interference lithography. The relationship between the experiments was made in terms of intensity distribution, considering a vectorial approach, where the superposition of two plane waves was used as a starting point. Within the limits considered in Young's experiment, the results show that the intensity distribution of both experiments coincide. In addition, this study provides a broader discussion on light interference, particularly the use of this phenomenon in technological applications.
DOI: 10.6084/m9.figshare.14325926
title: Detection of exoplanet transits using a small telescope

description: Abstract In this paper we describe how to observe a planetary transit using a small aperture telescope, as well as the strategies used to select the object, make the observations, the treatment and the data analysis. As an example, we observed the planetary transit on the WASP 76 star and estimated the transit time, the radius, the orbit semi major-axis and the orbital inclination of the planet. The results show that telescopes with modest instrumental configuration can be used to obtain satisfactory data about exoplanets that transit bright stars. Based on this result, we propose that it is possible to do observational astronomy with small-aperture telescopes, such as the instruments that exist in the different small-observatories installed in universities and a research centers in Brazil, to provide scientific literacy for undergraduate students and from high school students.
DOI: 10.6084/m9.figshare.14325926.v1
title: Detection of exoplanet transits using a small telescope

description: Abstract In this paper we describe how to observe a planetary transit using a small aperture telescope, as well as the strategies used to select the object, make the observations, the treatment and the data analysis. As an example, we observed the planetary transit on the WASP 76 star and estimated the transit time, the radius, the orbit semi major-axis and the orbital inclination of the planet. The results show that telescopes with modest instrumental configuration can be used to obtain satisfactory data about exoplanets that transit bright stars. Based on this result, we propose that it is possible to do observational astronomy with small-aperture telescopes, such as the instruments that exist in the different small-observatories installed in universities and a research centers in Brazil, to provide scientific literacy for undergraduate students and from high school students.
DOI: 10.6084/m9.figshare.14326388
title: Photon spherical orbits around a Kerr black hole

description: Abstract Black holes are trapped spacetime regions. Their inexorable gravitational attraction determines that nothing – not even light – may escape from this region. Thus, a black hole cannot be directly observed. It must be studied by the way it influences the motion of matter particles and light rays in its neighborhood. These trajectories are determined (within a certain approximation) by the black hole geometry's geodesics. In particular, null geodesics – those followed by light rays – possess considerable astrophysical interest: they represent how the radiation emitted around the black hole, or incoming from far away sources, is distorted by the black hole. In this work we present the equations of motion of light rays in the Kerr geometry, that describes a rotating black hole, making use of Hamilton-Jacobi theory. Subsequently, we analyze the conditions for the existence of spherical photon orbits around the black hole. These orbits, representing strong light bending, are the key to determine the optical appearance of the black hole. Finally, using computational methods, we exhibit plots illustrating some of these trajectories.
DOI: 10.6084/m9.figshare.14326388.v1
title: Photon spherical orbits around a Kerr black hole

description: Abstract Black holes are trapped spacetime regions. Their inexorable gravitational attraction determines that nothing – not even light – may escape from this region. Thus, a black hole cannot be directly observed. It must be studied by the way it influences the motion of matter particles and light rays in its neighborhood. These trajectories are determined (within a certain approximation) by the black hole geometry's geodesics. In particular, null geodesics – those followed by light rays – possess considerable astrophysical interest: they represent how the radiation emitted around the black hole, or incoming from far away sources, is distorted by the black hole. In this work we present the equations of motion of light rays in the Kerr geometry, that describes a rotating black hole, making use of Hamilton-Jacobi theory. Subsequently, we analyze the conditions for the existence of spherical photon orbits around the black hole. These orbits, representing strong light bending, are the key to determine the optical appearance of the black hole. Finally, using computational methods, we exhibit plots illustrating some of these trajectories.
DOI: 10.6084/m9.figshare.14326391.v1
title: A didactic-mathematical proposal for using the Planck scale: from photons to black holes

description: Abstract In this paper we present a theoretical study of the physical limits associated with a fundamental particle, the photon, in the Planck scale. In addition, we calculated the temperature of a black hole with Planck dimensions. From the dimensional analysis, we verified five units of the Planck scale (mass, time, length, energy, and temperature). First, we analyze a photon with dimensions of Planck length; Then we identify the energy of this photon with the wavelength of the order of the Schwarzschild ray ( r s ). Finally, we calculate the temperature of a black hole with Planck's dimensions (in this case, with its Schwarzschild radius equal to the Planck's length). The “photon ray” appears as a multiple of Planck's length, demonstrating the inaccessibility of scales smaller than Planck's due to the Uncertainty Principle. Among the results obtained, we can highlight three possible paths to the Planck scale, as well as the smallest possible photon measurement according to the laws of physics, which is characterized by maximum frequency and energy.
DOI: 10.6084/m9.figshare.14326391
title: A didactic-mathematical proposal for using the Planck scale: from photons to black holes

description: Abstract In this paper we present a theoretical study of the physical limits associated with a fundamental particle, the photon, in the Planck scale. In addition, we calculated the temperature of a black hole with Planck dimensions. From the dimensional analysis, we verified five units of the Planck scale (mass, time, length, energy, and temperature). First, we analyze a photon with dimensions of Planck length; Then we identify the energy of this photon with the wavelength of the order of the Schwarzschild ray ( r s ). Finally, we calculate the temperature of a black hole with Planck's dimensions (in this case, with its Schwarzschild radius equal to the Planck's length). The “photon ray” appears as a multiple of Planck's length, demonstrating the inaccessibility of scales smaller than Planck's due to the Uncertainty Principle. Among the results obtained, we can highlight three possible paths to the Planck scale, as well as the smallest possible photon measurement according to the laws of physics, which is characterized by maximum frequency and energy.
DOI: 10.6084/m9.figshare.14326394.v1
title: Onsager and Debye models for pure polar fuids

description: Abstract In 1936, Lars Onsager obtained an equation that relates the dielectric constant of pure polar fluids to the permanent dipole moment of its constituent molecules, and also to the refractive index, the density and the temperature of the medium. In this paper, we guide the reader to find the Onsager equation, demanding from him or her, however, basic knowledge on electrostatic in matter and on classical statistical mechanics - particularly on the canonical ensemble -, both at an undergraduate level. Along the way - and this is our main interest in this work - we discuss modeling in physics. In an additional section, we discuss the Debye model as resulting from a mean field approximation applied to the Onsager model, and we show the Clausius-Mossotti model as a particular case of the Debye and Onsager models. Suggested use of this text: in the study or teaching of additional topics in undergraduate or graduate courses in classical electrodynamics, statistical mechanics, or physical chemistry.
DOI: 10.6084/m9.figshare.14326394
title: Onsager and Debye models for pure polar fuids

description: Abstract In 1936, Lars Onsager obtained an equation that relates the dielectric constant of pure polar fluids to the permanent dipole moment of its constituent molecules, and also to the refractive index, the density and the temperature of the medium. In this paper, we guide the reader to find the Onsager equation, demanding from him or her, however, basic knowledge on electrostatic in matter and on classical statistical mechanics - particularly on the canonical ensemble -, both at an undergraduate level. Along the way - and this is our main interest in this work - we discuss modeling in physics. In an additional section, we discuss the Debye model as resulting from a mean field approximation applied to the Onsager model, and we show the Clausius-Mossotti model as a particular case of the Debye and Onsager models. Suggested use of this text: in the study or teaching of additional topics in undergraduate or graduate courses in classical electrodynamics, statistical mechanics, or physical chemistry.
DOI: 10.6084/m9.figshare.14326395.v1
title: Physical Pendulum Damped by Dry Friction

description: Abstract In this work, pendular movement damped by dry friction was studied. Dry friction differs from viscous friction by: a) the amplitude of oscillation linearly decays, whereas in the viscous damping the oscillation decays exponentially; b) the frequency of oscillation is keeping in presence of dry friction, however, the frequency of oscillation is reduced due to damping factor in viscous case. Some experiments were performed using a wood clapboard suspended and oscillating in lateral contact with a flat plate and using a DVD suspended by an axis stuck on its edge, where the friction was in this axis. The movements were recorded an analyzed with aid of software Tracker. It was possible to obtain decay parameters and friction force in both cases. Also, viscous damping forces were calculated due to drag from the air and showed to be negligible with respect to dry friction.