An experimental and numerical investigation about bandwidth enhancement of dielectric resonator antennas (DRAs) using multiple DRAs, arranged according to a ‘stacked’ configuration is reported. The antenna consists of two cylindrical discs of the dielectrics Cr_0.75Fe_1.25O₃ (CRFO) and Fe_0.5Cu_0.75Ti_0.75O₃ (FCTO) stacked vertically, placed above a ground plane and excited by a coaxial probe. The lateral edge of the cylinder should be placed against the feed probe, which excites the ${\rm HEM}_{11{\rm \delta}}$ mode. The numerical procedure is performed through a software package based on the finite-element method. An excellent agreement between theoretical and experimental results is observed. The concept of increasing the bandwidth of the DRA by stacking is verified. For the first time, the temperature coefficient of resonant frequency (τ_f) was also measured for CRFO and FCTO ceramics.

The materials sizing in nano-scale is a challenge to be overcome, because the size determined by various methods differ. In order to shed light about the nanomaterials sizing, a modified Scherrer's equation was applied to estimate more accurately the nanostructured titanium dioxide crystal size. The manufactured titanium dioxide-nanostructured powder with nominal average size about 21nm was used as the reference standard to determine the accurate of modified equation. From X-ray diffraction data, an average crystal size about 20.63 nm was achieved for unheated sample. To establish a relation between the result obtained with modified Scherrer's equation and the nominal average crystal size, a statistical treatment and a comparative assessment were performed. The average absolute divergence does not exceed 0.70 nm. The value of crystal size determined from X-ray data was in good agreement with that informed by the supplier. Additionally, the behavior of sample was studied as a function of temperature.

Electrophoretic deposition is a straightforward, environmentally friendly, and cost-effective technique for depositing and synthesizing nanomaterials, particularly nanofilms of semiconductors. Key parameters in electrophoresis include deposition time and voltage. Zinc oxide, a semiconductor of significant interest in solar energy research, possesses favorable characteristics, notably, a band gap value of approximately 3.33 eV. In the realm of dye-sensitized solar cells, which represent the third generation of solar cells, zinc oxide has emerged as a compelling choice for a photoanode. This study focused on depositing thin films of zinc oxide through electrophoresis and applying them as photoanodes in dye solar cells. The results demonstrated that the electrodeposited films exhibited good reflectance in the visible spectrum (~60–90%), a band gap energy of 3.28 eV, and an incident photon conversion efficiency of approximately 4.48% for the electrodeposited film at 80 V for 5 min.

Tin Zinc Oxide thin films were deposited on transparent conductive oxide by chemical bath, at percentages of 5, 10 and 15% of tin (Sn) on the zinc oxide (ZnO) structure. All films were thermally treated to improve its crystallinity. The produced films with tin were characterized by x-ray diffraction and optical measurements, such as absorbance, transmittance and reflectance. The x-ray spectrum showed the formation of the ZnO wurtzite and the crystallite size of the films were calculated to be 53.74; 79.59 and 66.38 nm for the photoanodes at 5, 10 and 15% of tin (Sn), respectively, on the zinc oxide structure. The calculated band gap energy of the films revealed that the presence of tin can reduce the band gap energy to about 3.2 eV. Those films were used as photoanodes on dye sensitized solar cells (DSSC) to observe the effects of the tin (Sn) on the photovoltaic activity of the zinc oxide (ZnO) semiconductor. Parameters such as efficiency and short circuit current density were particularly affected by the presence of tin in the composition, with the 5% Sn ZnO film presenting the best results of 7.56 % efficiency and 34.35 mA/cm2, short circuit current density, the other films presented lower values for efficiency, which can be attributed to lower values of short-current density.

Purpose: Conducting a bibliometric analysis of papers on the Life Cycle Assessment (LCA) of motor vehicles published over the last 20 years. Theoretical framework: Bibliometric analysis, a discipline within scientometrics, uses mathematical and statistical methods to synthesize and evaluate publications, identifying trends and structures in specific research fields. Method: The bibliometric analysis was conducted using data from Scopus and Web of Science, and it assessed the impact and trends of scientific production, correlating keywords to explore connections between themes. Articles from the last two decades were analyzed to quantify the relevance of the studied topic. Results and conclusion: Using the Bibliometrix algorithm in R, 512 published articles were analyzed. The results indicated a significant increase in research output in this field of study, as demonstrated by the substantial growth in the number of published articles and citations. Research implications: This bibliometric study reveals key trends and guides future innovations in the environmental and transportation sectors, highlighting the transition towards more sustainable options. Originality/value: This groundbreaking work provides valuable insights into the life cycle of vehicles with various propulsion technologies, emphasizing the evolution and environmental impacts of electric, hybrid, internal combustion, and fuel cell vehicles.