Previous Issue
Volume 2, September

Table of Contents

Physics, Volume 2, Issue 4 (December 2020) – 8 articles

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
Order results
Result details
Select all
Export citation of selected articles as:
Open AccessArticle
Examination of Chaotic Structures in Semiconductor or Alloy Voltage Time-Series: A Complex Network Approach for the Case of TlInTe2
Physics 2020, 2(4), 624-639; https://doi.org/10.3390/physics2040036 - 20 Nov 2020
Viewed by 249
Abstract
This paper proposes a method for examining chaotic structures in semiconductor or alloy voltage oscillation time-series, and focuses on the case of the TlInTe2 semiconductor. The available voltage time-series are characterized by instabilities in negative differential resistance in the current–voltage characteristic region, [...] Read more.
This paper proposes a method for examining chaotic structures in semiconductor or alloy voltage oscillation time-series, and focuses on the case of the TlInTe2 semiconductor. The available voltage time-series are characterized by instabilities in negative differential resistance in the current–voltage characteristic region, and are primarily chaotic in nature. The analysis uses a complex network analysis of the time-series and applies the visibility graph algorithm to transform the available time-series into a graph so that the topological properties of the graph can be studied instead of the source time-series. The results reveal a hybrid lattice-like configuration and a major hierarchical structure corresponding to scale-free characteristics in the topology of the visibility graph, which is in accordance with the default hybrid chaotic and semi-periodic structure of the time-series. A novel conceptualization of community detection based on modularity optimization is applied to the available time-series and reveals two major communities that are able to be related to the pair-wise attractor of the voltage oscillations’ phase portrait of the TlInTe2 time-series. Additionally, the network analysis reveals which network measures are more able to preserve the chaotic properties of the source time-series. This analysis reveals metric information that is able to supplement the qualitative phase-space information. Overall, this paper proposes a complex network analysis of the time-series as a method for dealing with the complexity of semiconductor and alloy physics. Full article
(This article belongs to the Section Applied Physics)
Show Figures

Figure 1

Open AccessArticle
Generalized Inequalities to Optimize the Fitting Method for Track Reconstruction
Physics 2020, 2(4), 608-623; https://doi.org/10.3390/physics2040035 - 11 Nov 2020
Viewed by 215
Abstract
A standard criterium in statistics is to define an optimal estimator as the one with the minimum variance. Thus, the optimality is proved with inequality among variances of competing estimators. The demonstrations of inequalities among estimators are essentially based on the Cramer, Rao [...] Read more.
A standard criterium in statistics is to define an optimal estimator as the one with the minimum variance. Thus, the optimality is proved with inequality among variances of competing estimators. The demonstrations of inequalities among estimators are essentially based on the Cramer, Rao and Frechet methods. They require special analytical properties of the probability functions, globally indicated as regular models. With an extension of the Cramer–Rao–Frechet inequalities and Gaussian distributions, it was proved the optimality (efficiency) of the heteroscedastic estimators compared to any other linear estimator. However, the Gaussian distributions are a too restrictive selection to cover all the realistic properties of track fitting. Therefore, a well-grounded set of inequalities must overtake the limitations to regular models. Hence, the inequalities for least-squares estimators are generalized to any model of probabilities. The new inequalities confirm the results obtained for the Gaussian distributions and generalize them to any irregular or regular model. Estimators for straight and curved tracks are considered. The second part deals with the shapes of the distributions of simplified heteroscedastic track models, reconstructed with optimal estimators and the standard (non-optimal) estimators. A comparison among the distributions of these different estimators shows the large loss in resolution of the standard least-squares estimators. Full article
(This article belongs to the Section Applied Physics)
Show Figures

Figure 1

Open AccessArticle
Study of Friction Force in Electrodynamic Rail Accelerator: Experiment and Interpretation Using FEM Modelling
Physics 2020, 2(4), 596-607; https://doi.org/10.3390/physics2040034 - 25 Oct 2020
Viewed by 373
Abstract
The paper presents experimental data and a model of an electromagnetic rail accelerator. The model includes an equivalent circuit, magnetic field in the system and movement of the projectile (that is solved separately) which is computed numerically. The main results are compared with [...] Read more.
The paper presents experimental data and a model of an electromagnetic rail accelerator. The model includes an equivalent circuit, magnetic field in the system and movement of the projectile (that is solved separately) which is computed numerically. The main results are compared with our experimental data and friction force during acceleration is evaluated. Full article
(This article belongs to the Section Applied Physics)
Show Figures

Figure 1

Open AccessArticle
An Experimental Test of the Classical Interpretation of the Kaluza Fifth Dimension
Physics 2020, 2(4), 587-595; https://doi.org/10.3390/physics2040033 - 22 Oct 2020
Viewed by 361
Abstract
Kaluza was the first to realize that the four-dimensional gravitational field of general relativity and the classical electromagnetic field behave as if they were components of a five-dimensional gravitational field. We present a novel experimental test of the macroscopic classical interpretation of the [...] Read more.
Kaluza was the first to realize that the four-dimensional gravitational field of general relativity and the classical electromagnetic field behave as if they were components of a five-dimensional gravitational field. We present a novel experimental test of the macroscopic classical interpretation of the Kaluza fifth dimension. Our experiment design probes a key feature of Kaluza unification—that electric charge is identified with motion in the fifth dimension. Therefore, we tested for a time dilation effect on an electrically charged clock. This test can also be understood as a constraint on time dilation from a constant electric potential of any origin. This is only the second such test of time dilation under electric charge reported in the literature, and a null result was obtained here. We introduce the concept of a charged clock in the Kaluza context, and discuss some ambiguities in its interpretation. We conclude that a classical, macroscopic interpretation of the Kaluza fifth dimension may require a timelike signature in the five-dimensional metric, and the associated absence of a rest frame along the fifth coordinate. Full article
(This article belongs to the Section Classical Physics)
Show Figures

Figure 1

Open AccessArticle
Log-Normal Superstatistics for Brownian Particles in a Heterogeneous Environment
Physics 2020, 2(4), 571-586; https://doi.org/10.3390/physics2040032 - 19 Oct 2020
Viewed by 413
Abstract
Superstatistical approaches have played a crucial role in the investigations of mixtures of Gaussian processes. Such approaches look to describe non-Gaussian diffusion emergence in single-particle tracking experiments realized in soft and biological matter. Currently, relevant progress in superstatistics of Gaussian diffusion processes has [...] Read more.
Superstatistical approaches have played a crucial role in the investigations of mixtures of Gaussian processes. Such approaches look to describe non-Gaussian diffusion emergence in single-particle tracking experiments realized in soft and biological matter. Currently, relevant progress in superstatistics of Gaussian diffusion processes has been investigated by applying χ2-gamma and χ2-gamma inverse superstatistics to systems of particles in a heterogeneous environment whose diffusivities are randomly distributed; such situations imply Brownian yet non-Gaussian diffusion. In this paper, we present how the log-normal superstatistics of diffusivities modify the density distribution function for two types of mixture of Brownian processes. Firstly, we investigate the time evolution of the ensemble of Brownian particles with random diffusivity through the analytical and simulated points of view. Furthermore, we analyzed approximations of the overall probability distribution for log-normal superstatistics of Brownian motion. Secondly, we propose two models for a mixture of scaled Brownian motion and to analyze the log-normal superstatistics associated with them, which admits an anomalous diffusion process. The results found in this work contribute to advances of non-Gaussian diffusion processes and superstatistical theory. Full article
(This article belongs to the Section Statistical Physics and Nonlinear Phenomena)
Show Figures

Figure 1

Open AccessArticle
A Full-Fledged Analytical Solution to the Quantum Harmonic Oscillator for Undergraduate Students of Science and Engineering
Physics 2020, 2(4), 541-570; https://doi.org/10.3390/physics2040031 - 17 Oct 2020
Viewed by 413
Abstract
The quantum harmonic oscillator is a fundamental piece of physics. In this paper, we present a self-contained full-fledged analytical solution to the quantum harmonic oscillator. To this end, we use an eight-step procedure that only uses standard mathematical tools available in natural science, [...] Read more.
The quantum harmonic oscillator is a fundamental piece of physics. In this paper, we present a self-contained full-fledged analytical solution to the quantum harmonic oscillator. To this end, we use an eight-step procedure that only uses standard mathematical tools available in natural science, technology, engineering and mathematics disciplines. This solution is accessible not only for physics students but also for undergraduate engineering and chemistry students. We provide interactive web-based graphs for the reader to observe the shape of the wave functions for an electron and a proton when both are subject to the same potential. Each of the eight steps in our solution procedure is treated as a separate problem in order to allow the reader to quickly consult any step without the need to review the entire article. Full article
(This article belongs to the Section Physics Education)
Open AccessArticle
The Formulations of Classical Mechanics with Foucault’s Pendulum
Physics 2020, 2(4), 531-540; https://doi.org/10.3390/physics2040030 - 01 Oct 2020
Viewed by 621
Abstract
Since the pioneering works of Newton (1643–1727), mechanics has been constantly reinventing itself: reformulated in particular by Lagrange (1736–1813) then Hamilton (1805–1865), it now offers powerful conceptual and mathematical tools for the exploration of dynamical systems, essentially via the action-angle variables formulation and [...] Read more.
Since the pioneering works of Newton (1643–1727), mechanics has been constantly reinventing itself: reformulated in particular by Lagrange (1736–1813) then Hamilton (1805–1865), it now offers powerful conceptual and mathematical tools for the exploration of dynamical systems, essentially via the action-angle variables formulation and more generally through the theory of canonical transformations. We propose to the (graduate) reader an overview of these different formulations through the well-known example of Foucault’s pendulum, a device created by Foucault (1819–1868) and first installed in the Panthéon (Paris, France) in 1851 to display the Earth’s rotation. The apparent simplicity of Foucault’s pendulum is indeed an open door to the most contemporary ramifications of classical mechanics. We stress that adopting the formalism of action-angle variables is not necessary to understand the dynamics of Foucault’s pendulum. The latter is simply taken as well-known and simple dynamical system used to exemplify and illustrate modern concepts that are crucial in order to understand more complicated dynamical systems. The Foucault’s pendulum first installed in 2005 in the collegiate church of Sainte-Waudru (Mons, Belgium) will allow us to numerically estimate the different quantities introduced. Full article
(This article belongs to the Section Physics Education)
Show Figures

Figure 1

Open AccessArticle
Electron Beam Transport in Plasma-Accelerator-Driven Free-Electron Lasers in the Presence of Coherent Synchrotron Radiation and Microbunching Instability
Physics 2020, 2(4), 521-530; https://doi.org/10.3390/physics2040029 - 30 Sep 2020
Viewed by 384
Abstract
Laser- and beam-driven plasma accelerators promise electron beam brightness at the exit of plasma cells suitable for X-ray free-electron lasers. Beam transport from the accelerator to the undulator may include a multi-bend, energy-dispersive switchyard, in which energy collimators can be installed to protect [...] Read more.
Laser- and beam-driven plasma accelerators promise electron beam brightness at the exit of plasma cells suitable for X-ray free-electron lasers. Beam transport from the accelerator to the undulator may include a multi-bend, energy-dispersive switchyard, in which energy collimators can be installed to protect the undulator or to serve multiple photon beamlines. Coherent synchrotron radiation and microbunching instability in the switchyard can seriously degrade the brightness of the accelerated beam, reducing the lasing efficiency. We present a semi-analytical analysis of those collective effects for beam parameters expected at the exit of state-of-the-art plasma accelerators. Prescriptions for the linear optics design used to minimize transverse and longitudinal beam instability are discussed. Full article
(This article belongs to the Special Issue Plasma Accelerators and Artificial Intelligence)
Show Figures

Figure 1

Previous Issue
Back to TopTop