rss_2.0Annals of West University of Timisoara - Physics FeedSciendo RSS Feed for Annals of West University of Timisoara - Physics of West University of Timisoara - Physics 's Cover Method of Assessment of Coefficient of Permeability and Porosity of Soil of a Poultry Farmland<abstract><title style='display:none'>Abstract</title><p>Leachate collected at the bottom of dead bird’s disposal pits may leak and migrate to pollute groundwater when soils and rocks present are porous. This study assessed the coefficient of permeability (K) and porosity (Ф) of soils and rocks in poultry farmland using 2 Dimensional (2D) electrical resistivity method and soil analysis. Geo-electrical data collection was achieved by using the dipole-dipole array. The field resistivity measurement was carried out along three traverse lines (three Profiles) of 100 m long which were oriented along with East-West directions. These measurements were taken in the order of increasing in offset distance interval of 5 m. The acquired apparent resistivity data were inverted using DIPPROWIN modeling software to perform 2D data inversion. Five soil samples from different locations at depths of 0 – 15 cm and 15 – 30 cm, on the poultry farmland, were collected, transported, and tested in the laboratory. K and Ф were determined using falling head and density methods respectively. The results obtained from the processed field resistivity data from the three profiles were presented as field data pseudo-sections, theoretical pseudo-section, and 2D resistivity structures. The 2D resistivity structure revealed three structures viz; highly conductive, slightly conductive, and resistive. The resistivity values of these structures ranged from 14.1-99.0 Ω m, 100-848 Ω m, and 1350-90330 Ω m respectively. The highly conductive structures were found in profiles 1 and 3 due to the downward migration of the contaminants from the dead bird disposal pit 1 and the feces disposal site through clayey sand soil. This occurs at the depth range of few meters from the surface to greater than 20 m. The presence of the slightly conductive structure is a result of filtration of the contaminants by the soil materials which increased the resistivity of the soil. The movement of the contaminant through the soil is an indication of the porous and permeable nature of the farmland. The resistive structure is only noticeable in profiles 1 and 2 but very prominent at the depth range of 5 m to more than 20 m and 5 m to 35 m along the profile length. The results of the analysis of the five soil samples from the poultry farmland showed a high value of 0.552 and 3.554 <italic>x</italic> 10−<sup>2</sup>cm/s of porosity (Ф) and coefficient of permeability (K) respectively. A strong correlation of <italic>R</italic><sup>2</sup> = 0.9878 existed between Ф and K. With these results geo-electrical method had successfully assessed Ф and K of the soil of the poultry farmland.</p></abstract>ARTICLE2021-10-08T00:00:00.000+00:00Ag Continuous Doped SnO Sensor Selective to Co in Presence of Ethanol at Room Temperature<abstract><title style='display:none'>Abstract</title><p>This paper contains experimental research to minimize the basic limits of the SnO<sub>2</sub> semiconductor oxide gas sensor. The operating temperature is high. In addition, their selectivity diminishes with gasses having the same chemical behavior. An experimental methodology is presented to overcome the difficulties of these metal oxides. The efficiency of the gas sensors made of Ag continuously doped at room temperature is excellent. At the end of the testing processes and security measures supplied, laboratory tests and experiments will be conducted to guarantee the acceptability of the planned study.</p></abstract>ARTICLE2021-09-17T00:00:00.000+00:00Diffusion Magnetic Resonance Imaging with Applications to Cardiac Muscle: Short Review<abstract><title style='display:none'>Abstract</title><p>This review describes in brief recent magnetic resonance imaging (MRI) methods for assessing cardiac structure in healthy and pathologic state using diffusion-weighted (DW) and diffusion tensor imaging (DTI) approaches. A background on the theory and MR pulse sequences employed in DW/DT imaging is given, along with the calculation of diffusion tensor (D), apparent diffusion coefficient (ADC) and fractional anisotropy (FA). Parametric maps derived from DW/DT images can quantify microstructure alterations due to fibrotic collagen deposition, along with associated changes in cardiac muscle anisotropy. Representative examples of ADC and FA parametric maps are shown from <italic>ex vivo</italic> high-resolution DT images of explanted healthy and scarred hearts obtained from pre-clinical investigations. Furthermore, examples of fiber tractography demonstrating DTI-based 3D (three-dimensional) reconstruction of fiber directions within the heart are illustrated using advanced open-source software. Lastly, future developments and potential translation of DW/DT methods into routine clinical evaluation for cardiac MR imaging protocols are highlighted.</p></abstract>ARTICLE2020-12-16T00:00:00.000+00:00Electro-Magnetic Behavior of Highly Correlated Fluorides KFeF, KCoF and KNiF: A Comparative Study of Cation Effect<abstract><title style='display:none'>Abstract</title><p>Fluorides-based perovskites are currently the typical materials being used in spintronic devices, optoelectronic and magneto-resistance colossal fields. Solar cells made of Fluoro-perovskite hold much promise for the future of solar energy. The electronic structure and magnetic properties of KFeF<sub>3</sub>, KCoF<sub>3</sub> and KNiF<sub>3</sub> Fluorides are studied using ab initio Calculation. We have analysed the structural phases, total and partial electronic densities and band structures within the (DFT) vs the DFT+U description. We show the Electro-Magnetic Behavior using L(S)DA+U vs L(S)DA in a comparative study of cation effect by integrating three types of crystal structures (Cubic (Pm-3m), Four-Layered Hexagonal (P6/mmc), and Orthorhombic (Pnma)). Equilibrium lattices agree very well with experimental and theoretical data. Magnetic moment of each phase is discussed. The obtained results confirmed that the three crystal structures invested here exhibit Ferromagnetic (FM) behavior. The introduction of the Hubbard’s parameter U increases lattice parameters and magnetic moment. We deduce that the second cation plays an important role in the magnetic effects. L(S)DA+U show correctly that KFeF<sub>3</sub>, KCoF<sub>3</sub> and KNiF<sub>3</sub> are insulators.</p></abstract>ARTICLE2020-12-16T00:00:00.000+00:00Structural Stability and Magnetic Ordering in BiFeO Perovskite Oxide: A Comparative Study GGA+U vs L(S)DA+U<abstract><title style='display:none'>Abstract</title><p>Ab initio calculations of BiFeO<sub>3</sub> magnetic perovskite are carried. Accurate density functional theory calculations were performed considering a U-Hubbard correction (DFT+U) to account for on-site Coulomb interactions of the 3d-Fe states. We have applied the Full-potential linearized augmented plane waves (FP-LAPW) method. Exchange-correlation effects are treated using the Local Spin Density approximation (L(S)DA+U) vs generalized gradient approximations (GGA+U). Equilibrium lattices agree very well with other theoretical and experimental data. The magnetization energy differences between Spin Up and Spin Dn states are small. Spin effect and magnetic moment obtained from subsequent (L(S)DA+U) and (GGA+U) calculations are also discussed in different magnetic configurations: The Ferromagnetic cubic phase (Pm-3m), The A-type Antiferromagnetic (P4/mmc) and The G-type Antiferromagnetic (Fm-3m). The nature of magnetism arises mainly from the Fe-site exhibiting a G-type antiferromagnetic ordering. The electronic structure shows that BiFeO<sub>3</sub> has a metallic band gap. This multiferroic exhibit strong hybridization of the 3d-Fe and 2p-O orbitals. Therefore, the Multiferroic BiFeO<sub>3</sub> perovskite has driven significant research interest due to their promising technological potential. It’s a good candidate for potential applications in spintronic, and to aid the development of the next generation of data storage and multi-functional technological devices.</p></abstract>ARTICLE2020-12-16T00:00:00.000+00:00Theoretical Study of the Electronic Properties of XYZ (X = Fe, Co; Y = Zr, Mo; Z = Ge, Sb) Ternary Heusler: Abinitio Study<abstract><title style='display:none'>Abstract</title><p>In the purpose of exploring new Heusler alloys with different magnetic applications, we have employed first principles calculations method within density functional theory. After checking the structural stability of X<sub>2</sub>YZ Heusler alloys (X = Fe, Co; Y =Zr, Mo and Z = Ge, Sb), we found that Cu<sub>2</sub>MnAl type structure is more favorable for most compounds except for X<sub>2</sub>MoGe and Co<sub>2</sub>MoSb, were the Hg<sub>2</sub>CuTi structure is energetically more stable. The trends in magnetic and electronic structures can be predicted by the structure types as well as the different kinds of hybridizations between the constituents. Among the two series only two compounds were identified to be true half metals with potential applications in spintronic devices. While one compound was classified as a nonmagnetic semiconductor with a small band gap. For the rest of materials, we found that the metallic behavior is dominant. These materials show possible interesting features in technical applications as well. The effect of distortion on the magnetic properties of Co<sub>2</sub>ZrGe and Fe<sub>2</sub>ZrSb showed that the half metallic character was preserved within a moderate range of volume changes, which makes it possible to grow these materials as thin films with modern techniques.</p></abstract>ARTICLE2020-12-16T00:00:00.000+00:00Optimizing Configurations for Determining the Electromagnetic Properties of CsFeF, NaFeF, and RbFeF Fluorides: GGA vs GGA+U and TB-mBj Approaches<abstract><title style='display:none'>Abstract</title><p>The structural, electronic and magnetic properties of (Cubic Pm-3m, Hexagonal-4H, orthorhombic Pnma, and orthorhombic Pbnm) phases of AFeF<sub>3</sub> Fluorides (A = Cs, Na, and Rb) are reported theoretically using full potential linearized augmented plane waves method within the density functional theory (DFT). Using different exchange–correlation approximations including the generalized gradient approximation (PBE-GGA, WC-GGA, and PBEsol-GGA), also (GGA) with Hubbard potential (GGA + U) and The modified Becke Johnson potential <italic>(mBJ)</italic>, we carried to determine various physical properties. The Calculations revealing that the estimated structural parameters are reliable with the experimentally reported data. Magnetically all these intermetallics are Ferromagnetic (FM). The ground-state energy of different magnetic phases studied showed that the magnetic moments are evaluated per atom, and overestimated by (GGA+U). Transfer charge reveals a strong covalent interaction between Fe-Fe atoms. Their electronic band structure and density of states indicate insulator behavior.</p></abstract>ARTICLE2020-12-16T00:00:00.000+00:00Investigation of Electronic and Optical Properties of Novel Oxychalcogenides by Density Functional Theory<abstract><title style='display:none'>Abstract</title><p>The search for a new material with unparalleled properties has attracted the interest of the scientific community due to rapid development of technology and it can be very inspiring to the future experiments. In this paper, electronic structure and optical properties of the new rare earth coinage-metal chalconegides YCuChO (Ch=S, Se, Te) are investigated in detail using state-of-the art density functional theory (DFT). Both the GGA-PBEsol and TB-mBJ functionals were used to describe the exchange-correlation interactions. These compounds are novel and have not been synthesized before. The optimized structural parameters, viz., lattice parameters and atomic position coordinates, are predicted. The analyses of the electronic properties indicate that the studied compounds are wide direct bandgap semiconductors. The calculated bandgaps varying from 1.69 eV (for the Te compound) to 2.5 eV (for the S compound) with the mBJ approach. Moreover, the optical properties of these compounds were comprehensively studied and discussed in terms of the dielectric function and loss function. The results provide theoretical support for the exploration of YCuChO (Ch=S, Se, Te) materials in potential optoelectronic applications.</p></abstract>ARTICLE2020-12-16T00:00:00.000+00:00Electronic and Thermoelectric Properties of Li-Based Half-Heusler Alloys: A DFT Study<abstract><title style='display:none'>Abstract</title><p>In this paper, we have studied the electronic, elastic and thermoelectric properties of the half-Heusler LiCrZ (Z = C, N, Si, and P) materials in Type II phase, in this structure the atomic occupations are X (1/2,1/2,1/2), Y (0,0,0) and Z(1/4,1/4,1/4). The ferromagnetic state of Type II structure was found to be the most stable phase for all studied alloys. After calculating the elastic constants, we found out that the conditions of mechanical stability were verified only for LiCrSi and LiCrP alloys in Type II phase, at both equilibrium a<sub>0</sub> and half metallic a<sub>hm</sub> lattice constants, which indicates that these two compounds can be synthesized experimentally. We should also mention that the half metallic behavior in Type II structure, for LiCrSi and LiCrP compounds, was obtained by straining the equilibrium lattice constants by 2% and 6%, respectively. At a<sub>hm</sub>, these two systems were identified to be true half metals due to their complete spin polarization and integer value of total magnetic moment. These last ones have reached 3μ<sub>B</sub> per unit cell when Z = Si, and 4μ<sub>B</sub> when Z = P. Using the mean field approximation (MFA), the Curie temperatures of Type II structure were also determined, where the values are estimated to be 456.2 K and 302.8 K, respectively. Finally, the thermoelectric performance has been explored by the classical Boltzmann theory. At low temperatures, the figure of merit has reached 0.73 and 0.93 for LiCrSi and LiCrP, respectively. The considerable ZT values and all calculated physical properties make these two systems promising candidates for thermoelectric applications.</p></abstract>ARTICLE2020-12-16T00:00:00.000+00:00Study the Effect of Cu Doping on Optical and Structural Properties of NiO Thin Films<abstract><title style='display:none'>Abstract</title><p>In this work, copper doped nickel oxide as the thin films have been elaborated by a spin coating method, the nickel chloride hexahydrate (0.8M) and copper (II) chloride dehydrate (Cu/Ni = 0, 2.15, 4.3, 8.6 and 12.9 At.%) were used to prepare the Cu doped NiO thin films. The Cu doped NiO thin films were heated at a crystallization temperature of 600 °C with 2 h. The obtained thin films by spin coater method have a film thickness in the order of 400 nm. The prepared Cu doped NiO thin films have a polycrystalline with cubic structure (200) peak was observed. The optical property shows that the prepared thin films have a transmittance of about 70 %. The Cu doped NiO thin films have minimum bandgap energy is 3.85 eV at 12.9 at.%, the thin film deposited at 8.6 at.% has the highest value of Urbach energy is 425 meV. The Cu doped NiO thin films have a high electrical conductivity of 8.6 at% it is 7 (Ω.cm)<sup>−1</sup>. The prepared Cu doped NiO thin film was suitable for gas sensing applications due to the existing phase and higher electrical conductivity.</p></abstract>ARTICLE2020-12-16T00:00:00.000+00:00First-Principles Calculations of the Structural, Electronic and Optical Properties of Yttrium-Doped SnO<abstract><title style='display:none'>Abstract</title><p>We use FP-LAPW method to study structural, electronic, and optical properties of the pure and Y-doped SnO<sub>2</sub>. The results show that by Y doping of SnO<sub>2</sub> the band gaps are broadened, and still direct at Γ-point. For pure SnO<sub>2</sub> material, the obtained values of the direct band gap are 0.607 eV for GGA-PBE and 2.524 eV for GGATB-mBJ, respectively. This later is in good agreement with the experimental data and other theoretical results. The Fermi level shifts into the valence band and exhibits p-type semiconductor character owing mainly from the orbital 4d-Y. Additionally, the calculated optical properties reveal that all concentrations are characterized by low reflectivity and absorption via wavelength λ (nm) in the visible light and near-infrared (NIR) ranges, which leads to a redshift in the optical transparency.</p></abstract>ARTICLE2021-07-12T00:00:00.000+00:00Structural, Chemical and Optical Properties of Pure and Al-Doped Zno Thin Films Derived by Sol–Gel Dip Coating Process<abstract><title style='display:none'>Abstract</title><p>Pure and Al-doped ZnO thin films were successfully deposited with sol-gel dip coating on both substrates Si (100) and glass. The structural, chemical, morphological and optical properties as a function of the annealing temperature and dopant atomic concentration were investigated by means of X-ray diffraction, Energy dispersive X-ray, Scanning Electron Microscopy, and spectrophotometry. All the pure and doped films show a polycrystalline nature and hexagonal in structure. Accurate doping was proven by EDX. In addition, the SEM analysis revealed that the films possess uniform distribution throughout the surface and the grain dimension decreases with Al doping. From the transmittance measurements, it is see that all films are over 55% in the visible region and the band gap energy increases from 3.28 to 3.45 eV with the increase of Al concentration.</p></abstract>ARTICLE2021-07-12T00:00:00.000+00:00Determination of the Spread of Heavy Metal from Ori-Ile Battery Waste Dumpsite Using Electrical Resistivity Method<abstract><title style='display:none'>Abstract</title><p>Contaminants from waste dumpsites have become sources of concern. Disposed wastes (Heavy metal) from battery industries could contaminate soil, agricultural plants, and groundwater. Therefore, this study aimed at the determination of the migration of heavy metal (Lead) from a Battery Waste Dumpsite using the electrical resistivity method. Using Schlumberger array, fifteen (15) Vertical Electrical Soundings (VES) were carried out around a Battery Waste Dumpsite in Ori –Ile, Ikumapaiyi at Olodo community, Ibadan, Oyo State, Nigeria. Preliminary analyses of VES data were performed and were fed into software (WINRESIST 1.0) for qualitative interpretation to reveal apparent resistivity values, the number of layers, and thickness. Three and four layers of topsoil, sandy-clayed, weathered/fractured basement, and basement were obtained. Various values of lowest apparent resistivity and depths of penetration of leached lead on the four sides of the battery waste dumpsite were obtained. The lowest apparent resistivity values obtained were converted to apparent conductivity and plotted against the distance of each VES point. Five collected water samples from available hand-dug wells around the dumpsite were analyzed for the presence of lead using an Atomic Absorption Spectrometer. Graph of apparent conductivity against VES distance indicated a decrease in conductivities with distance, an indication of reduction of Concentration of lead with distance. The level of Lead ranged from 0.081 to 0.770 mg/L which was above the tolerance level of 0.01 mg/L of WHO and SON, an indication of heavy metal pollution in groundwater. This study has established that lead ions were present in groundwater and had spread to a distance of 80 m from the battery waste dumpsite and were more pronounced on the southern region of the dumpsite.</p></abstract>ARTICLE2021-07-12T00:00:00.000+00:00Study of the Structural, Optical, Electrical and Morphological Properties of Nickel Sulfide Thin Films Used in Supercapacitors<abstract><title style='display:none'>Abstract</title><p>Nickel sulfide (NiS) thin film has been deposited on glass substrates by spray-pyrolysis at 325 ± 5 °C. The precursor aqueous solution was synthetized using hexahydrated nickel nitrates and thiourea. The structural, morphological, optical and electrical properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy and four probes electrical measurements. The XRD analysis confirmed the hexagonal structure of NiS thin film, which was found to crystalize along [010] direction with an average crystallites size of 10.5 nm. The lattice parameters are a = b = 3.420 Å and c = 5.300 Å in the space group P6<sub>3</sub>/mmc. The optical properties of the films were investigated through the transmittance and the reflectance measurements. The results revealed that the material exhibits a direct optical band gap of 1.03 eV. The elementary composition analysis confirmed the presence of Ni and S with a stoichiometry ratio (Ni/S) of 1.05. The morphology analysis revealed a homogenous crack-free, compact appearance and a granular surface in all scanned areas. The average roughness of the surface was 6.48 nm. On the other hand, the film exhibits a high electrical conductivity ca. 1.10 × 10<sup>5</sup> S/cm at room temperature. The above results show that the prepared NiS in this study has a good crystallization, dense morphology, good stoichiometric ratio and high conductivity; therefore, it stands as a potential candidate for application in supercapacitors as an electrode material.</p></abstract>ARTICLE2021-01-29T00:00:00.000+00:00Note On The Schrödinger Equation<abstract><title style='display:none'>Abstract</title><p>A second-order formalism leading to an equation describing the same dynamics as the Schrödinger one is developed under some compatible initial conditions.</p></abstract>ARTICLE2015-10-05T00:00:00.000+00:00Using Algebraic Computing To Teach General Relativity And Cosmology<abstract><title style='display:none'>Abstract</title><p>The article presents some new aspects and experience on the use of computer in teaching general relativity and cosmology for undergraduate students (and not only) with some experience in computer manipulation. Some years ago certain results were reported [1] using old fashioned computer algebra platforms but the growing popularity of graphical platforms as Maple and Mathematica forced us to adapt and reconsider our methods and programs. We will describe some simple algebraic programming procedures (in Maple with GrTensorII package) for obtaining and the study of some exact solutions of the Einstein equations in order to convince a dedicated student in general relativity about the utility of a computer algebra system.</p></abstract>ARTICLE2015-10-05T00:00:00.000+00:00On A Schwarszchild-Like Metric<abstract><title style='display:none'>Abstract</title><p>In this short Note we would like to bring into the attention of people working in General Relativity a Schwarzschild like metric found by Professor Cleopatra Mociuţchi in sixties. It was obtained by the A. Sommerfeld reasoning from his treatise "Elektrodynamik" but using instead of the energy conserving law from the classical Physics, the relativistic energy conserving law.</p></abstract>ARTICLE2015-10-05T00:00:00.000+00:00LIDAR Measurements Comparison Of Two Volcanic Eruptions: Environmental Influences Upon The Romanian Territory<abstract><title style='display:none'>Abstract</title><p>The eruption of both the Eyjafjallajokull (April 2010) and Grimsvotn (May 2011) volcanoes cumulated with two moments that gave headaches to the authorities and air traffic, and their impact on the environment upon Iasi region have been studied by means of different tools evidencing the complexity of the phenomena. In order to evidence the intrusion of pollutants in the cloud systems and to obtain additional data on the intrusion when the ash cloud was over our country, LIDAR measurements, meteorological (NMA), Satellite data (EUMETSAT), and various forecasting models (ECMWF, VAAC-Met Office, HYSPLIT) have been used. The new 3D Atmospheric Observatory Site of the Alexandru Ioan Cuza University of Iasi, as part of RADO (Romanian Atmospheric 3D Observatory) is presented, too.</p></abstract>ARTICLE2015-10-05T00:00:00.000+00:00On Both Spatial And Velocity Distribution Of Sputtered Particles In Magnetron Discharge<abstract><title style='display:none'>Abstract</title><p>The kinetics of the sputtered atoms from the metallic target as well as the time-space distribution of the argon metastable atoms have been investigated for DC and high power pulse magnetron discharge by means of Tunable Diode – Laser Absorption Spectroscopy (TD-LAS) and Tunable Diode – Laser Induced Fluorescence (TD-LIF). The discharge was operated in argon (5-30 mTorr) with two different targets, tungsten and aluminum, for pulses of 1 to 20 μs, at frequencies of 0.2 to 1 kHz. Peak current intensity of ~100 A has been attained at cathode peak voltage of ~1 kV. The mean velocity distribution functions and particle fluxes of the sputtered metal atoms, in parallel and perpendicular direction to the target, have been obtained and compared for DC and pulse mode.</p></abstract>ARTICLE2015-10-05T00:00:00.000+00:00Quarter Car Suspension System With One Degree Of Freedom Simulated Using Simulink<abstract><title style='display:none'>Abstract</title><p>Simulate the behavior of a quarter car suspension system with Simulink®. Consider only vertical movement of the car, neglecting roll and pitch. All movements of the car axes are modeled as having equal amplitude. The characteristic equations that describe the behavior of dynamical systems based on FBD (Free Body Diagram) of automotive suspension. We make the simulation model in six steps. In simulation we consider the damping coefficient, <italic>c</italic>, variable. The rest of parameters are constant (mass, speed and stiffness). The simulation parametrs are defined in Mathlab®. We follow the final signal created on the oscilloscope. At the end of the study, we concluded the effect of damping coefficient changes over the comfort.</p></abstract>ARTICLE2015-10-05T00:00:00.000+00:00en-us-1