Temperature oscillation in one-dimensional superlattice induced by phonon localization

Thermal transport properties and thermodynamic quantities often present anomalous behaviors in low-dimensional systems. In this paper, we find that temperature oscillates spatially in one dimensional harmonic and weakly anharmonic superlattice. With the increase of anharmonicity, the temperature oscillation gradually disappears and a normal temperature gradient forms. Further analysis reveals that the formation of temperature oscillation is due to the localization of high frequency phonons which cannot be thermalized. Moreover, the localized modes interact weakly with heat reservoirs, thus, their contributions to local temperature remain negligible while varying the temperatures of heat reservoirs. The oscillated temperature profile is in a good agreement with Visscher's formula. These discoveries of temperature oscillation phenomenon have great potential in applications of phononic devices for heat manipulation.

Structural Analysis and Mechanical Properties of Thermal Battery by Flexible PCM

An ancient BTM with PCM was controlled through the issues of high inflexibility of phase change material, leakage problems and very low conductivity in thermal energy. This research paper reports a facile batter thermal management and creativity along with induced non-rigid phase change material composites. This battery model can be determined by the flexible phase change material composites along with an intervention due to the recovery in shape and non-rigidity of flexible phase change components. This assemble was modeled to be efficient and compact without any requirement for grease. A constant state reveals various stages of phase change material which has various properties in thermal efficiency. A unified state was linked with the recovery shape of flexible phase change components which can cause a low resistance in FCPCM and battery. Battery thermal management demonstrates the perfect process of thermal control power. If the battery was discharged from 90 to 10% of charge, then the temperature of flexible phase change components depends upon battery thermal management. It was 44.5°C during the 3.5°C rate which was 29.8°C lower than no phase change material. It also reveals low-temperature oscillation inside the long-time process and range of heat of recovered phase change material. The performance of battery thermal management and its flexibility will give perceptions of passive battery thermal management systems.

Hafnium Zirconium Oxide Thin Films for CMOS Compatible Pyroelectric Infrared Sensors

Pyroelectric infrared sensors are often based on lead-containing materials, which are harmful to the environment and subject to governmental restrictions. Ferroelectric Hf1−xZrxO2 thin films offer an environmentally friendly alternative. Additionally, CMOS integration allows for integrated sensor circuits, enabling scalable and cost-effective applications. In this work, we demonstrate the deposition of pyroelectric thin films on area-enhanced structured substrates via thermal atomic layer deposition. Scanning electron microscopy indicates a conformal deposition of the pyroelectric film in the holes with a diameter of 500 nm and a depth of 8 μm. By using TiN electrodes and photolithography, capacitor structures are formed, which are contacted via the electrically conductive substrate. Ferroelectric hysteresis measurements indicate a sizable remanent polarization of up to 331 μC cm−2, which corresponds to an area increase of up to 15 by the nanostructured substrate. For pyroelectric analysis, a sinusoidal temperature oscillation is applied to the sample. Simultaneously, the pyroelectric current is monitored. By assessing the phase of the measured current profile, the pyroelectric origin of the signal is confirmed. The devices show sizable pyroelectric coefficients of −475 μC m−2 K−1, which is larger than that of lead zirconate titanate (PZT). Based on the experimental evidence, we propose Hf1−xZrxO2 as a promising material for future pyroelectric applications.

Thermophysical Properties of Temperature-Sensitive Paint

The complex thermophysical property of temperature-sensitive paint (TSP) research is discussed. TSP is used for visualization of the surface temperature distribution in wind tunnel aerodynamic tests. The purpose of this research was to provide reliable, experimental, thermophysical data of the paint applied as a coating. As TSP is applied as thin surface layers, investigation of its final properties is challenging and demands the application of non-standard procedures. At present, most measurements were performed on composite specimens of TSP deposed onto a thin metallic film substrate or on TSP combined with a cellulose sheet support. The studies involved gravimetric,, thermogravimetric, and microcalorimetric analyses, transversal thermal diffusivity estimation from laser flash data and in-plane effective thermal diffusivity measurements done by the temperature oscillation technique. These results were complemented with scanning electron microcopy analysis, surface characterization and the results of dilatometric measurements performed on the TSP bulk specimens obtained from liquid substrate by casting. Complex analysis of the obtained results indicated an isotropic characteristic of the thermal diffusivity of the TSP layer and provided reliable data on all measured thermophysical parameters—they were revealed to be typical for insulators. Further to presenting these data, the paper, in brief, presents the applied investigation procedures.

Global Climate modelling of Saturn to determine the nature of its equatorial oscillation

<p><strong>Introduction:</strong> The Saturn's Semi-Annual Oscillation (SSAO) observed by Cassini is a source of debate within the community, because of its similarities (sometimes conflicting) with both the terrestrial Quasi-Biennial Oscillation (QBO) and the terrestrial Semi-Annual Oscillation (SAO). As the QBO, the downward propagation of the SSAO occurs almost to the tropopause (Schinder et al. 2011). In contrast, the half a Saturn year period of the SSAO is advocated for a seasonal forcing and hints the SAO mechanism driving. Moreover, observation of anomalies in warm temperature and high hydrocarbon concentration at winter tropics is interpreted as the downwelling branch of a meridional stratospheric circulation. <br>Using DYNAMICO-Saturn Global Climate Model (GCM) -- with an higher vertical discretization (96 vertical levels from 3x10<sup>5 </sup>to 10<sup>-1 </sup>Pa) than previous works (Spiga et al. 2020, Bardet et al. 2021)  -- we performed simulations lasting at 13 simulated Saturn years, to study Saturn's stratospheric equatorial oscillation, its inter-hemispheric circulation and the driving mechanism connecting them. </p><p><strong>Results:</strong> Firstly, DYNAMICO-Saturn depicts a stratospheric equatorial oscillation of temperature and zonal wind. The new vertical resolution permits to stabilize more the oscillation periodicity and its eastward phase compared to previous study. The period varies between 0.5 and 1 simulated Saturn years. Indeed, because of irregularity in the waves and eddy-to-mean forcings, the downward propagation is carried out by episodes of descent followed by episodes of stagnation at a given level of pressure. The amplitude of the associated temperature oscillation is under-estimated by 10 K compared to the Cassini observations.</p><p>Secondly, DYNAMICO-Saturn also models an inter-hemispheric circulation taking place from the summer tropical latitudes to the winter ones, with a strong subsidence between 20 and 40° in the winter hemisphere. The main subsidence branch is located in the same latitude region as temperature and hydrocarbons anomalies observed by Cassini (Guerlet et al. 2009, 2010, Sinclair et al. 2013, Fletcher et al. 2015 and Sylvestre et al. 2015). Furthermore, eddy-to-mean interaction diagnostics show that the phases of Saturn's equatorial oscillation are controlled by the inter-hemispheric circulation. During the solstices, the cross-equatorial drift of the inter-hemispheric circulation, associated to the forcing of the mid-latitude planetary-scale Rossby waves, drive the equatorial zonal wind to westward direction. In contrast, during the equinoctial overturning of the inter-hemispheric circulation, the residual mean circulation is reduced to an unique ascendance at the equator to permit the transport and eastward moment deposition of Kelvin waves from the troposphere.</p><p><strong>Perspectives:</strong> This present modelling study of the dynamics of Saturn's stratosphere confirms the SAO-like character of the Saturn's equatorial oscillation. However, we will also explore the putative part of the QBO-like character of it. We plan to use this new vertical resolution combine to the subgrid-scale gravity wave parameterization. </p>