Thermo-Optical Mechanical Waves in a Rotating Solid Semiconductor Sphere Using the Improved Green–Naghdi III Model

The current study investigates thermophotovoltaic interactions using a new mathematical model of thermoelasticity established on a modification of the Green–Naghdi model of type III (GN-III). The basic equations, in which the heat transfer is in the form of the Moore–Gibson–Thompson (MGT) equation, are derived by adding a single delay factor to the GN-III model. The impact of temperature and electrical elastic displacement of semiconductors throughout the excited thermoelectric mechanism can be studied theoretically using this model. The proposed model was used to investigate the interactions between the processes of thermoelastic plasma in a rotating semiconductor solid sphere that was subjected to a thermal shock and crossed to an externally applied magnetic field. The influence of rotation parameters on various photothermal characteristics of silicon solid was presented and explored using the Laplace technique.

Rotating spacetimes generalizing Lifshitz black holes

We present a spinning black hole solution in d dimensions with a maximal number of rotation parameters in the context of the Einstein–Maxwell-Dilaton theory. An interesting feature of such a solution is that it accommodates Lifshitz black holes when the rotation parameters are set to zero. We verify the rotating nature of the black hole solution by performing the quasi-local analysis of conserved charges and defining the corresponding angular momenta. In addition, we perform the thermodynamical analysis of the black hole configuration, show that the first law of thermodynamics is completely consistent, and obtain a Smarr-like formula. We further study the thermodynamic stability of the constructed solution from a local viewpoint, by computing the associated specific heats, and from a global perspective, by using the so-called new thermodynamic geometry. We finally make some comments related to a pathology found in the causal structure of the obtained rotating black hole spacetime and compute some of its curvature invariants.

A New Factor Predicting Excessive Femoral Anteversion in Patients with Recurrent Patellar Dislocation

Purpose Determining a new imaging method on full-leg standing lower limb radiographs to predict excessive femoral anteversion in patients with patellar dislocation.Methods This study included 119 patients with patellar dislocation from January 2014 to January 2021. The femoral anteversion and tibial torsion were measured by CT scanning. The medial condylar angle was measured by the full-leg standing lower limb radiographs. Pearson correlation coefficient was used to evaluate the correlation between rotation parameters and medial condylar angle.Results Included patients were divided into DFO group and control group according to whether they received derotational femoral osteotomy (DFO) operation or not. There were significant statistical differences in femoral anteversion, tibial torsion and medial condylar angle between DFO group and control group (P < 0.05). This showed that there was a smaller medial condylar angle in patients undergoing DFO operation. Correlation analysis showed that the values of femoral anteversion were significantly correlated with medial condylar angle (r= -0.719, P < 0.001). Conclusion This study showed that medial condylar angle had a negative correlation with excessive femoral anteversion on the full-leg standing lower limb radiographs. The medial condylar angle can be a good predictor of femoral anteversion and can be used to guide the performance of DFO to treat patellar dislocation in clinical practice.

Cosmological constant effect on charged and rotating black hole shadows

Motivated by recent astrophysical observations, we investigate the shadow behaviors of four-dimensional charged rotating black holes with a cosmological constant. This study is made in terms of a reduced moduli space parameterized by the charge and the rotation parameters. For fixed observers, we analyse in some details the shadow behaviors and the corresponding naked singularities of Kerr–Newman and Kerr–Sen four-dimensional black holes in Anti-de Sitter backgrounds. Then, a comparative discussion is provided by computing the geometrical observables and the energy emission rate.

Earth Rotation Parameters Estimation Using GPS and SLR Measurements to Multiple LEO Satellites

Earth rotation parameters (ERP) are one of the key parameters in realization of the International Terrestrial Reference Frames (ITRF). At present, the International Laser Ranging Service (ILRS) generates the satellite laser ranging (SLR)-based ERP products only using SLR observations to Laser Geodynamics Satellite (LAGEOS) and Etalon satellites. Apart from these geodetic satellites, many low Earth orbit (LEO) satellites of Earth observation missions are also equipped with laser retroreflector arrays, and produce a large number of SLR observations, which are only used for orbit validation. In this study, we focus on the contribution of multiple LEO satellites to ERP estimation. The SLR and Global Positioning System (GPS) observations of the current seven LEO satellites (Swarm-A/B/C, Gravity Recovery and Climate Experiment (GRACE)-C/D, and Sentinel-3A/B) are used. Several schemes are designed to investigate the impact of LEO orbit improvement, the ERP quality of the single-LEO solutions, and the contribution of multiple LEO combinations. We find that ERP estimation using an ambiguity-fixed orbit can attain a better result than that using ambiguity-float orbit. The introduction of an ambiguity-fixed orbit contributes to an accuracy improvement of 0.5%, 1.1% and 15% for X pole, Y pole and station coordinates, respectively. In the multiple LEO satellite solutions, the quality of ERP and station coordinates can be improved gradually with the increase in the involved LEO satellites. The accuracy of X pole, Y pole and length-of-day (LOD) is improved by 57.5%, 57.6% and 43.8%, respectively, when the LEO number increases from three to seven. Moreover, the combination of multiple LEO satellites is able to weaken the orbit-related signal existing in the single-LEO solution. We also investigate the combination of LEO satellites and LAGEOS satellites in the ERP estimation. Compared to the LAGEOS solution, the combination leads to an accuracy improvement of 0.6445 ms, 0.6288 ms and 0.0276 ms for X pole, Y pole and LOD, respectively. In addition, we explore the feasibility of a one-step method, in which ERP and the orbit parameters are jointly determined, based on SLR and GPS observations, and present a detailed comparison between the one-step solution and two-step solution.

A Numerical Study on Cross Diffusion Cattaneo-Christov Impacts of MHD Micropolar Fluid Across a Paraboloid

Analyzing the impacts of Cattaneo-Christov flux, bioconvective Raleigh number and cross diffusion effects in electrically conducting micropolar fluid through a paraboloid revolution is assessed in this work. Non-dimensional equations are solved numerically using shooting technique with an aid of Matlab software. The impact of various parameters on velocity, temperature and concentration are discussed in detail and presented graphically. Harman number and micro rotation parameters are found and have an increasing influence on shear stress. The vertical velocity increases at free stream and the horizontal velocity increases near the surface when Grb increases, which follows the opposite trend for accumulation of Rb. The numerical results are compared with the available data indicating good agreement in a limiting case.

Combination of GNSS and VLBI data for consistent estimation of Earth Rotation Parameters

&lt;p&gt;We present the current activities of the Federal Agency for Cartography and Geodesy (BKG) towards a combined processing of VLBI and GNSS data.&amp;#160; The main goal of the combined analyses of the two different space-geodetic techniques is the improvement of the consistency between the techniques through common parameters, i.e., mainly Earth Rotation Parameters (ERPs), but also station coordinates and tropospheric parameters through local ties and atmospheric ties, respectively.&lt;/p&gt;&lt;p&gt;Based on our previous combination studies using GNSS data and VLBI Intensive sessions on a daily and multi-day level, we generate a consistent, low-latency ERP time series with a regular daily resolution for polar motion and dUT1. We achieved in this way a significant accuracy improvement of the dUT1 time series and a slight improvement of the pole coordinates time series, comparing ERPs from the combined processing with the individual technique-specific ERPs.&lt;/p&gt;&lt;p&gt;In our recent studies, we extend the combination of GNSS and VLBI Intensive sessions by adding VLBI 24-hour sessions in order to exploit the benefit of the combination to its maximum extend. We analyse the impact of the combination on the global parameters of interest, i.e., mainly dUT1, polar motion and LOD, but also on station coordinates.&lt;/p&gt;&lt;p&gt;BKG&amp;#8217;s primary interest is the combination of GNSS and VLBI data on the observation level. However, the current combination efforts are based on the normal equation level using technique-specific SINEX files as a starting point.&lt;/p&gt;

On the potential of single-satellite space ties to achieve the Global Geodetic Observing System goals

&lt;p&gt;GGOS-SIM-2, funded by the German Research Foundation (DFG), is a research collaboration project between the German Research Center for Geosciences (GFZ) and the Technische Universit&amp;#228;t Berlin (TUB). Simulations are utilized to examine the potential of co-location in space, called space ties, of the four main space geodetic techniques, i.e. DORIS, GNSS, SLR and VLBI to achieve the requirements of the Global Geodetic Observing System (GGOS) for a global terrestrial reference frame (TRF), 1 mm accuracy and 1 mm / decade long-term stability. The simulations are performed for six fictional orbit scenarios, including proposed missions GRASP (USA) and E-GRASP (EU), and expanded by a variation of the E-GRASP orbit with lower eccentricity as well as three higher orbiting circular orbits with different inclination over a time span of seven years. For most realistic simulations, we first evaluated real DORIS, GPS and SLR observations to the satellites LAGEOS 1 und 2, Ajisai, LARES, Starlette, Stella, ENVISAT, Jason 1 und 2, Sentinel 3A and B using Precise Orbit Determination (POD), to get detailed information about the individual station and receiver accuracy, availability and further technique-specific effects. Then, we generate simulated single-technique TRF solutions based on existing missions and add the co-location-in-space satellite in the six orbit scenarios. In order to quantify the effects of the different scenarios, we examine the added value w.r.t. the existing missions in terms of origin and scale and of formal errors of the station coordinates and Earth rotation parameters. We also investigate the impact of systematic errors on the derived orbits on the final TRF. The different techniques show individual advantages regarding the respective orbit parameters. For instance, a higher eccentricity of the orbit seems to lead to improved accuracy of length-of-day (LOD) from SLR. The results will help to find the best trade-off for a satellite that co-locates all four techniques in space towards a GGOS-compliant TRF and Earth rotation parameters.&lt;/p&gt;