Abstract. The early contributions of Ştefan Procopiu to Plasma Physics are presented and discussed, highlighting his role as a pioneer in this research field in Romania. Beyond the historical relevance of the presented results, Procopiu's works are a vivid example of clarity and precision, as well as rigorous scientific writing.

Abstract. We numerically demonstrate the existence of parabolic and rectangular self-similar propagations of optical beams in saturable media. Rectangular selfsimilar evolution is achieved by imposing an external optical potential (lattice) that acts as a pulse shaping mechanism and it is shown that a rectangular shaped profile can be obtained by providing a delicate balance between the nonlinearity and saturation of the medium.

Abstract. In this work, a new integrable (3+1)-dimensional Bogoyavlensky-Konopelchenko equation is reported. Using Wolfram Mathematica, the complete Painlevé integrability of this equation is examined. The Hirota's method is implemented to formally derive two sets of multiple soliton solutions that result from two distinct cases of parameters. Moreover, we provide families of lump solutions through symbolic Maple computation. Other exact solutions with distinct structures, such as kink, periodic, and singular waveforms will be also determined. We expect that this model and its solutions will contribute to explaining many phenomena in different branches of science in general, and in plasma and fluid physics in particular.

Abstract. In this paper, we consider the problem of identifying the unknown source function in the time-space fractional diffusion equation from the final observation data. An implicit difference technique is proposed in conjunction with the matrix transfer scheme for approximating the solution of the direct problem. The challenge pertains to an inverse scenario encompassing a nonlocal ill-posed operator. The problem under investigation is formulated as a regularized optimization problem with a least-squares cost function minimization objective. An approximation for the source function is obtained using an iterative non-stationary Tikhonov regularization approach. Three numerical examples are reported to verify the efficiency of the proposed schemes.

Abstract. This study introduces a newly discovered (3+1)-dimensional integrable Boussinesq equation (BE). The complete integrability of the equation in question is investigated through the utilization of Painlevé analysis. The method of Hirota's approach in its simplified form is employed to obtain a variety of soliton solutions of the BE. By using the Maple symbolic computation we obtain a set of lump solutions that are considered to be of a general class. The current model can help the researchers in studying different nonlinear phenomena that can arise in many different branches of science such as physics of fluids and plasma physics.

Abstract. Accelerator Mass Spectrometry (AMS) and cosmogenic nuclides techniques are used in quantitative geomorphological studies on large time scale. In order to accurately date surface exposure to cosmic rays, the amount of pure quartz taken into account, needs to be well determined. Depending on the particularity of the rocks, sometimes the presence of feldspar in geological samples hinders the accurate determination of ²⁶Al and ¹⁰Be by AMS. To overcome this problem, our paper proposes the assessment of quartz purity by SEM-EDX analysis, in an objective and facile way, compared to ICP-MS method. The proposed methodology is not only effective, but it shows features that save time and excessive consumption of reagents that often are not environment and health friendly.

Abstract. Reconstructing the state of a quantum system, called quantum state tomography, is an essential task in quantum technologies. Standard methods are inefficient, as they scale exponentially with the number of qubits. Better scaling methods, such as SIC-POVM tomography, are not yet widespread due to their measurement complexity. As such, there is an urgent need to find efficient and compact devices for performing tomography of photonic states. Here we present simulations of photonic devices implementing SIC-POVM tomography in photonic chips. We obtain fidelities F = 0.8452 (for qubits) and F = 0.7609 (for qutrits). Our results show that we can design efficient and compact SIC-POVM tomography modules for integrated-photonics quantum chips. Since integrated photonics is a major quantum technology platform, we expect our results to be instrumental in the future development of compact, costeffective quantum devices. Applications include quantum communications, quantum computing, quantum sensing and quantum imaging.

Abstract. Cu₂SnS₃ thin films emerged as promising materials for sustainable photovoltaics due to their earth-abundant constituents and great optoelectronic properties. The formation of secondary phases during synthesis poses challenges to achieving efficient performances. This study investigates the impact of secondary phases on the properties of CTS films.

Abstract. Indoor Air Quality in educational buildings plays an important role in students and professors performance and health, gaining much attention in recent years. This paper presents the results obtained in a one-year campaign of continuous real-time monitoring of Radon, TVOCs, and CO₂ concentrations, as well as of indoor relative humidity in three different educational spaces located on the ground floor of a university building. The air pollutants concentrations were compared with the recommended values reported by guidelines and were used for health risk assessment. The annual effective dose due to indoor Radon exposure was determined together with the hazard index due to indoor TVOCs and CO₂ exposure in university classrooms. The results showed in general, a suitable indoor air quality for learning and work.

Abstract. The article investigates the properties of small-scale probability density fluctuations for measurements of X, Y and Z-components of the Earth's magnetic field before the earthquake that took place in November 2022 in the southern European region. A comparison is made of the properties of the statistical functional corresponding to the measurements of the magnetic field for three spatially separated magnetovariational stations located at different geographical azimuths with respect to the point of the epicenter of the indicated event. It is shown that for all stations there is a significant topological similarity of the dependences corresponding to the specified functional, considered as a function of time.

Abstract. ANTELOPE revised locations, extracted from the INCDFP catalogue, were used as input data for relocation with JHD method. The basic idea behind this technique is to simultaneously determine an optimum 1-D structural model for the target area, to relocate the events and to fix a common set of station corrections. Under appropriate conditions, the station corrections reproduce the unmodelled velocity variations, and thus can significantly improve the location of events. These corrections are related to local effects characterizing the station site. The relocated earthquakes and quarry blasts using JHD better delimit specific clusters in comparison with routine catalog locations.

Abstract. The study tries to give a comparative look on construction materials, such as bricks and mortars/plasters, from different geographical places and historical periods. Although not enough to characterize these materials complexly, the X-Ray Fluorescence technique aims to provide quick answers to simple questions regarding some aspects related to the composition of construction materials, the pigments used, and to give rise some clues on the sources of raw materials. Radiocarbon dating using AMS method establishes the origin of the calcite: mechanically processed quarry limestone (giving no information about the “antropization time”) or mechanically and thermally processed (giving some suggestions on the real time of construction), providing information on historical periods, related to site-specific techniques. The interpretations were also supported by radiocarbon results obtained at the RoAMS Laboratory in IFIN-HH on other types of materials.

Abstract. In this work the computational characterization of p-type coaxial HPGe detectors was performed using GESPECOR code and nonlinear least squares optimization. To apply the nonlinear least squares estimation, a surrogate model was built, which well approximates the FEP efficiency provided by GESPECOR code using the grid-based interpolation. A procedure was also developed to estimate the optimal parameters of p-type coaxial HPGe detectors. Its application to a Canberra detector model GC3018 showed that it is possible to achieve accurate values of the FEP efficiency computed by GESPECOR code using the optimized parameters.

Abstract. The benefits of using didactic experiments in teaching Physics are well-known. In this paper a simple experiment for the study of the magnetic field created by axially symmetric series and parallel neodymium magnet arrangements, proposed for high-school or college/university-level students, is presented. The magnetic field is described by measuring both the magnetic flux density and the attraction force created by such systems. Modelling attempts are made in order to find some equivalent replacements, too.

Abstract. In this article we describe two interactive didactic tools made with Excel spreadsheets for the visualization of Lissajous figures obtained from the composition of perpendicular harmonic oscillations. With the first tool, undamped oscillations can be composed, and with the second, damped oscillations in a periodic regime. By entering the periods and amplitudes of the two harmonic oscillations as well as the phase difference between them, we can visualize the trajectory of the resulting oscillation next to the input data. For a moment of time entered in the input data, the Cartesian and polar coordinates of the mass point that executes the resultant oscillation, as well as its velocity, are calculated. By changing the moment of time we can simulate the motion of the mass point on the resulting trajectory and check the periodicity of the motion on the two axes. The manipulation of the input data, with a rapid feedback, allows the analysis of the trajectory of the mass point depending on the frequency ratio of the two oscillations and the phase difference between them. By modifying the Excel formulas in the spreadsheets, it is shown how the tool for the composition of the damped perpendicular oscillations can be obtained from the tool for the composition of the undamped perpendicular oscillations. Thus, for various values of the damping coefficient, we have the possibility to compare the Lissajous figures resulting from the composition of damped oscillations with the Lissajous figures deriving from the composition of the undamped oscillations. In the case of damping, we can demonstrate by graphical simulation that the motion of the mass point tends towards the origin of the coordinate system as we give increasing values to the time moment in the input data. By using these two tools in class, students can understand and assimilate more easily and in a pleasant way the composition of perpendicular harmonic oscillations and, at the same time, they can study the influence of damping on this phenomenon.

Abstract. This article explores the benefits and challenges of integrating computational tools in teaching electromagnetic oscillations. With the growing importance of computational tools in physics education, it is essential to incorporate them into the classroom for effective teaching and learning. We present the way in which these tools can enhance the students' understanding of complex concepts, provide opportunities for hands-on learning, and enable the visualization of abstract concepts. Additionally, we describe the utilization of Google Colab platform as user interface that allows students to interactively simulate electromagnetic oscillation in RLC (resistor, inductor, capacitor) circuits and compare the simulation results with experimental measurements obtained from a physical circuit. Finally, the article can offer insights for a successful integration of computational tools in teaching electromagnetic oscillations for boosting students' comprehension capabilities and prepare them for real-world applications.

Abstract. The cantilever beam for micro-electromechanical systems (MEMS) is a switch controlled by electrostatic forces acting on two plates of a capacitor. The top moving plate is an elastic beam with a certain polarity, while the bottom fixed plate has the opposite polarity. At the actuation voltage, the beam becomes unstable and collapses to the down state closing the switch. The elastic deformation is described by the Euler-Bernoulli beam equations. The orientation of the top moving plate is taken into account. The theoretical model is compared with experimental results.