物理最新文献

The present investigation of the rotating disk system is highly significant due to its many applications, such as in fluid thermal reactors, regulating fluidic systems and fluid stirring. Subject to the upper functions of the rotating disk, the Stefan blowing into the three-dimensional Reiner–Rivlin (R–R) fluid flow by the rotating disk affect the vertical direction. Thermal radiation and Cattaneo–Christov (CC) energy diffusion effects are examined into considering energy transport. The chemical reaction is accommodated in the concentration equation. The convective boundary conditions are considered in the disk surfaces. The ensuing nonlinear systems are determined by applying the Bvp4c routine along with the shooting method. The obtained outcomes are shown graphically with physical justification. The results show that R–R parameters cause a downturn in the radial and tangential velocity profiles as well as the temperature field. The curves of the temperature profile enhance with higher values of radiation parameter. Although this radiation falls onto the fluid surface and increases the temperature of the liquid as hot particles collide with cold particles, the skin friction coefficients decrease with suction. However, the heat and mass transfer rates are enhanced. The current model has been validated by comparing the simplified version of the investigation to a previously published article and a close agreement has been found.

Neutron transfer cross sections for ⁷Li+²⁰⁵Tl system were measured near Coulomb barrier energies using online (gamma )-ray detection technique. One neutron stripping, two neutron stripping, and one neutron pickup cross sections have been extracted and are compared with the Coupled Reaction Channel (CRC) calculations. The systematics of one and two neutron stripping and pickup cross sections with a ⁷Li projectile on several targets show an approximate universal behaviour. A comparison of integrated neutron transfer cross sections with complete and incomplete fusion cross sections available with ⁷Li projectile is presented to understand the systematic behaviour. The neutron transfer along with cumulative sum of complete and incomplete fusion was found to explain the estimated reaction cross section in ⁷Li+²⁰⁵Tl system.

For the even nuclei of (^{204-208})Rn, (^{214-218})Ra and (^{232-234})U, the simultaneous description of charge distribution and total kinetic energy are studied within the scission-point model. The calculated data are compared with experimental data from the literature. Correlations between these observables and other quantities of interest are analysed.

The motion of a long, axisymmetric bubble (fluid 1) inside a vertical peristaltic conduit containing a self-rewetting fluid (fluid 2) is discussed in this article. The fluid inside the tube and the floating bubble are immiscible, incompressible and have different densities. The peristaltic channel has two open ends. It is assumed that the bubble can move freely inside the tube without being restricted or deformed by the border wall. The effect of the density difference between the two fluids, Marangoni convection caused by the thermal and solutal gradient and an imposed back flow on the position and shape of the bubble have all been discussed. Motion of the bubble within a peristaltic tube, influenced by the Marangoni convection due to thermal and solutal gradients, has find various applications in the electrification of the atmosphere by sea bubbles, efficient mixing in microfluidic devices, improved cooling in heat exchangers, design of hydrophobic surfaces, spray coating thography techniques, enhanced mass transfer in chemical reactors, advancing various industrial and biomedical applications with precise fluid control. A mathematical model of the problem has been developed using a two-dimensional cylindrical polar coordinate system. The governing equations are in the form of linear partial differential equation and have been solved analytically. The effect of the thermo-solutal Marangoni convection in the microgravity region and the imposed back flow, impact of gravity-driven convection in the absence of the Marangoni convection or back flow, on the motion of bubble are discussed by plotting the position of the bubble. The initial radius and thermo-solutal Marangoni convection determine the bubble’s form as it evolves. When the initial radius falls below a critical value, the bubble becomes broader and shorter; conversely, when the original radius exceeds the crucial value, the bubble becomes longer and thinner.

Well-defined ferromagnetism (FM) with a very high Tc of about 800 K was found in laser-ablated WO₃ films grown on Si wafer substrates. It seems that the observed magnetism is surface related, and oxygen vacancies might play an important role in inducing FM into these oxide semiconductors. The very high Tc FM is observed for the first time in nanosized-WO₃, indicating a great potential for spintronic applications.

Undoped zinc oxide (ZnO) and Au/ZnO thin films have been deposited on glass substrates using spray pyrolysis and sputtering methods. The impact of substrate temperature and Au thickness on the structural, electrical, optical, and ethanol sensing properties of the deposited films has been investigated. X-ray diffraction (XRD) patterns reveal a polycrystalline structure across all samples. Notably, for pure ZnO deposited at 500 °C, the (002) orientation exhibits a substantial increase in intensity compared to samples deposited at other temperatures and the layer reaches its superior crystalline state. Substrate temperature demonstrates a significant effect on the electrical resistance of ZnO. Increasing the substrate temperature from 350 to 550 °C results in a notable decrease in sheet resistance, ranging from 34.4 [MΩ/cm²] to 54.2 [KΩ/cm²]. The ZnO film deposited at a substrate temperature of 500 °C displays the lowest sheet resistance. Sputter-depositing a 10 Å of gold (Au) on top of the ZnO layer results in a simultaneous decrease in sheet resistance from 54.2 [KΩ/cm²] to 7.02 [KΩ/cm²], while it doesn’t have considerable effect on the transparency of layer. The effect of substrate temperature on ethanol sensing characteristics of ZnO has been investigated. According to the results, at the temperature of 350 °C, ZnO layer has a superior response compared to the other samples. As the substrate temperature increases, the response of the layers decreases. The film deposited at 500 °C showing predominant orientation (002), demonstrates a weak ethanol sensing feature compared to other layers. Ethanol sensing characteristics of the Au/ZnO double layer were also examined, encompassing parameters such as dynamic response, sensitivity, response/recovery times, and operational temperature. Sputtering of Au on the top of ZnO exhibits a significant improvement in gas sensitivity. Further investigation indicates that increasing the Au thickness to 40 Å contributes to sensitivity increase. However, beyond this thickness, a diminishing trend in sensitivity has been observed. According to our search, there is no report for synthesis and characterization of Au/ZnO double layer by employing two methods of spray pyrolysis and sputtering. The layers exhibit superior homogeneity and crystallization compared to other reports. Also the layers exhibit excellent gas sensing properties toward ethanol gas. The response and recovery time have low values. The gas sensitivity of Au/ZnO thin film has high value of 5 toward 200 ppm ethanol gas. According to the selectivity graph by sputtering Au on top of ZnO layer the gas selectivity toward ethanol gas enhances. The layers show good stability.

In this study, we report a three-dimensional synthetic aperture imaging system realized by a terahertz time-domain spectrometer. The temporal waveforms of the terahertz pulses scattered by the object to be imaged are Fourier transformed to the frequency domain before image reconstruction by the back-projection algorithm. The resolution of the imaging system is close to the center wavelength of the terahertz pulses, as tested by a resolution test chart. We also demonstrate the ability of this imaging method in non-destructive evaluation applications by measuring the internal structures of a university badge. A three-dimensional terahertz image and a series of slice views of the badge are acquired. The terahertz images clearly show the surface shape and internal structures of the badge, and the logo of the university on the badge is successfully extracted from the three-dimensional terahertz image.

The total reaction cross sections for systems with medium–heavy-mass range targets of Sn isotopes including ¹¹⁶Sn, ¹¹⁸Sn, ¹²⁰Sn, and ¹²⁴Sn, along with different projectiles ranging from tightly bound to weakly bound and halo, were taken from the literature and compared by reducing them to eliminate trivial effects due to different sizes and different Coulomb barriers. In addition, for all the systems considered, one-channel calculations accounting only for fusion were performed to study the quantitative effect of the direct reaction channels on the total reaction cross section.

A high entropy alloy (HEA) coating was applied on Ti-6Al-4 V by electron beam cladding Al₇(CoFeNi)₈₆Ti₇ HEA powder. The optimal electron beam cladding parameters, determined through orthogonal experimental analysis, were: 64 kV accelerating voltage, 12 mA welding beam current, and 3 s scanning time. Microstructure, phase composition, nano-hardness and wear resistance of the coating prepared using optimal parameters were investigated. The primary phases in the top, middle, and bottom regions of the coating were identified as body-centered cubic (BCC) solid solution with Ti-rich compounds (NiTi, Ti₂Ni, and Ti₂Co), BCC + Ti_0.85Al_0.15, and Ti_0.85Al_0.15, respectively. The coating had an average grain size of 3.9 μm, and the dislocation density of the BCC phase was 1.51 × 10¹⁴/m². Due to the presence of compounds, fine grains, and high dislocation density, the coating achieved an average nano-hardness of 8.39 ± 0.29 GPa, approximately 1.8 times higher than that of Ti-6Al-4 V. Additionally, the wear rate of the cladded coating was 22.28 ± 4.56 × 10^− 6 mm³/(N·m), representing a 65.5% reduction compared to Ti-6Al-4 V.