Conductor Temperature Monitoring of High-Voltage Cables Based on Electromagnetic-Thermal Coupling Temperature Analysis

As a key state parameter of high-voltage cables, conductor temperature is an essential determinant of the current carrying capacity of cables, but in practice, this is difficult to measure directly during the operation of high-voltage cables. In this paper, the electromagnetic-thermal coupling analysis model of a 110 kV high-voltage cable is established using the finite element analysis software COMSOL. By analyzing the temperature distribution law of high-voltage cables under different load currents and ambient temperatures, the relationship between the change in the high-voltage cable surface temperature and the conductor temperature is deduced, which allows the monitoring of the high-voltage cable conductor temperature. Taking the 110 kV cable of the Yanzhong line in Shanxi Province as an example and using the electromagnetic-thermal coupling temperature field analysis method, the conductor temperature of the high-voltage cable can be measured using the data obtained from the cable surface temperature, which is measured by the self-developed Raman Distributed Temperature Sensor (RDTS) system with a maximum measurement error of about 2 °C. The method is easy to use and can achieve the accurate measurement of the conductor temperature without damaging the cable body.

Hubble-induced phase transitions on the lattice with applications to Ricci reheating

Using 3+1 classical lattice simulations, we follow the symmetry breaking pattern and subsequent non-linear evolution of a spectator field non-minimally coupled to gravity when the post-inflationary dynamics is given in terms of a stiff equation-of-state parameter. We find that the gradient energy density immediately after the transition represents a non-negligible fraction of the total energy budget, steadily growing to equal the kinetic counterpart. This behaviour is reflected on the evolution of the associated equation-of-state parameter, which approaches a universal value 1/3, independently of the shape of non-linear interactions. Combined with kination, this observation allows for the generic onset of radiation domination for arbitrary self-interacting potentials, significantly extending previous results in the literature. The produced spectrum at that time is, however, non-thermal, precluding the naive extraction of thermodynamical quantities like temperature. Potential identifications of the spectator field with the Standard Model Higgs are also discussed.

Anisotropic minimally interacting dark energy models with cosmic strings and a massive scalar field

This paper deals with the construction of locally rotationally symmetric (LRS) Bianchi type-II (B-II) cosmological models obtained by solving Einstein field equations coupled with an attractive massive scalar field (MSF) when the source of gravitation is the mixture of cosmic string cloud and anisotropic dark energy (DE) fluid which are minimally interacting. We have obtained exact cosmological models by using (i) shear scalar is proportional to the scalar expansion of the space–time and (ii) a power-law relation between the average scale factor of the universe and the scalar field. Our models represent string cosmological model and DE model in the presence of MSF. Using our model, we determine cosmological parameters such as energy densities, deceleration parameter, statefinders and equation of state parameter. We, also, present the tension density and energy density of the string. We discuss the physical aspects of these cosmological parameters. It is observed that our models represent accelerated expansion phenomenon of our universe as confirmed by Supernova Ia experiment.

Dynamic study of Weyl tensor corrected f(R) gravity

We investigate the cosmological and thermodynamic aspects of Weyl tensor corrected [Formula: see text] gravity. For this purpose, we assume some well-known cosmological bouncing scenarios such as symmetric bounce cosmology, oscillatory cosmology, matter bounce cosmology, little rip cosmology, superbounce cosmology and develop some cosmological parameters. For instance, the equation of state parameter [Formula: see text] describes the quintessence phase for symmetric bounce cosmology, vacuum phase for oscillatory, little rip and matter bounce cosmology while it gives both quintessence and vacuum phases for matter bounce cosmology. It is also observed that the squared speed of sound [Formula: see text] gives positive behavior for all models resulting in that the models assumed are stable. We evaluate generalized second law of thermodynamics which remains valid for all cosmological models except symmetric bounce cosmology. Moreover, we also investigate the thermal equilibrium condition [Formula: see text] and found its validity for all models except symmetric bounce cosmological model.

Chimera state in coupled map lattice of matrices

In recent years, a lot of research has focused on understanding the behavior of when synchronous and asynchronous phases occur, that is, the existence of chimera states in various networks. Chimera states have wide-range applications in many disciplines including biology, chemistry, physics, or engineering. The object of research in this paper is a coupled map lattice of matrices when each node is described by an iterative map of matrices of order two. A regular topology network of iterative maps of matrices was formed by replacing the scalar iterative map with the iterative map of matrices in each node. The coupled map of matrices is special in a way where we can observe the effect of divergence. This effect can be observed when the matrix of initial conditions is a nilpotent matrix. Also, the evolution of the derived network is investigated. It is found that the network of the supplementary variable $\mu$ can evolve into three different modes: the quiet state, the state of divergence, and the formation of divergence chimeras. The space of parameters of node coupling including coupling strength $\varepsilon$ and coupling range $r$ is also analyzed in this study. Image entropy is applied in order to identify chimera state parameter zones.

Multiparametric Sea State from Spaceborne Synthetic Aperture Radar for Near Real Time Services

<p>Spaceborne synthetic aperture radar (SAR) is a powerful tool for monitoring marine environmental parameters of the seas. The ability to work independently of sun illumination, cloud coverage and atmospheric conditions, as well as the capability of delivering spatial information, makes SAR one of the most perceptive instruments. The newest methods for processing SAR data with increased precision allow sea state fields to be estimated with local variabilities. For large areas in oceans where no <em>in-situ</em> measurements and only forecast predictions are available, this information is indispensable for global shipping and over human activity. Due to newest developments, the derived meteo-marine parameters can be transferred to weather services and to a ship’s bridge several minutes after acquisition, where the ship route can be optimized.</p> <p>The study presents a method and application for estimating series of integrated sea state parameters from satellite-borne SAR, allow processing of data from different satellites and modes in near real time (NRT). The developed Sea State Processor (SSP) estimates total significant wave height <em>H<sub>s</sub></em>, dominant and secondary swell and windsea wave heights, first, and second moment wave periods, mean wave period and period of wind sea. The algorithm was applied for the Sentinel-1 (S1) C-band Interferometric Wide Swath Mode (IW), Extra Wide (EW) and Wave Mode (WM) Level-1 (L1) products and also extended to the X-band TerraSAR-X (TSX) StripMap (SM) mode. The scenes are processed in raster and result in continuous sea state fields with the exception of S1 WV. Each 20 km × 20 km WV imagette, acquired every 100 km along the orbit, presents averaged values for each sea state parameter.</p> <p>The SSP was tuned and validated using two independent global wave models WAVEWATCH-3 (NOAA) and CMEMS (Copernicus) and NDBC buoys. The accuracy of <em>H<sub>s</sub></em> reaches an RMSE of 0.25  m by comparison with models (S1 WV); comparisons to NDBC worldwide buoys result into an RMSE of 0.31  m. Due to implemented parallelization, a fine rater step for scene processing can be practical applied: for example, S1 IW scene with coverage of 200  km  ×  250  km can be processed using raster step of 1  km (corresponds to ~50.000 subscenes) during minutes.</p> <p>The DLR Ground Station “Neustrelitz” applies SSP as part of a near real-time demonstrator service that involves a fully automated daily provision of surface wind and sea state parameters estimates from S1 IW for the North and Baltic Sea. All results and the presented methods are novel and provide a wide field for applications and implementations in prediction systems.</p>

Testing Primordial Black Holes with multi-band observations of the stochastic gravitational wave background

The mass distribution of Primordial Black Holes (PBHs) is affected by drops in the pressure of the early Universe plasma. For example, events in the standard model of particle physics, such as the W ±/Z 0 decoupling, the quark-hadron transition, the muon and pion becoming non-relativistic, and the annihilation of electrons and positrons, cause a suppression in the Equation of State parameter and leave peaks in the PBH mass function around 10-6, 2, 60, and 106 M ☉, respectively, in the case of a nearly scale-invariant primordial power spectrum. The superposition of unresolved mergers of such PBHs results in a stochastic gravitational-wave background (SGWB) that covers a wide range of frequencies and can be tested with future gravitational wave (GW) detectors. In this paper, we discuss how its spectral shape can be used to infer properties about inflation, the thermal history of the Universe, and the dynamics of binary formation in dense halos encoded in their merger rate formula. Although many of these physical effects are degenerate within the sensitivity of a single detector, they can be disentangled by the simultaneous observation of the SGWB at different frequencies, highlighting the importance of multi-frequency observations of GWs to characterize the physics of PBHs from the early to the late time Universe.