Thermodynamic Response Research Articles

Intense Cooling of the Upper Ocean with the Merging of Tropical Cyclones: A Case Study in the Southeastern Indian Ocean

The thermodynamic responses of the upper ocean to interacting tropical cyclones (TCs) were investigated using in-situ observations, remote sensing products and numerical models. The interactions between TC Seroja and TC Odette in the southeastern Indian Ocean occurred between 6 April and 9 April 2021 (centered at 20°S, 110°E ± 5° each direction), and included a stalling of the smaller TC Odette by the passing of TC Seroja and subsequent complete merging. Multiple interactions with complete merging are very rare but represent one of the most extreme forms of air-sea interaction. Despite an insufficient ocean heat content, the merging led to an intensification of TC Seroja and to an extent of cooling (~3.0°C within 72 hours) by upwelling of deep water that was previously known in the literature only from stronger TCs. The stalling of the weak TC Odette (6 April, (15°S, 105°E) led to an unexpectedly intensive cooling by 2.5°C. Merging occurred on 9 April (20.5°S, 108.5°E), and with this interaction a sudden reversal from a downward to an upward velocity of up to 30 m d–1 was observed with subsequent transitions from maxima in downward and upward velocities (–10 to 10 m d–1). As a consequence, strong upwelling processes in the upper 200 m occurred, which were confirmed by in-situ data from ARGO floats. The frequency of concurrent formation and binary interaction between TCs could increase in the future with global warming and, with it, the extreme thermodynamic responses of the upper ocean.

Direct observation of ultrafast cluster dynamics in supercritical carbon dioxide using X-ray Photon Correlation Spectroscopy

Supercritical fluids exhibit distinct thermodynamic and transport properties, making them of particular interest for a wide range of scientific and engineering applications. These anomalous properties emerge from structural heterogeneities due to the formation of molecular clusters at conditions above the critical point. While the static behavior of these clusters and their effects on the thermodynamic response functions have been recognized, the relation between the ultrafast cluster dynamics and transport properties remains elusive. By measuring the intermediate scattering function in carbon dioxide at conditions near the critical point with X-ray photon correlation spectroscopy, we directly capture the cross-over dynamics between 4 and 13 picoseconds, revealing the transition between ballistic and diffusive motion. Complementary analysis using large-scale molecular dynamics simulations reveals that this behavior arises from collisions between unbound molecules and clusters. This study provides direct evidence of the ultrafast momentum exchange between clusters, which has significant impact on transport properties, solvation processes, and reaction kinetics in supercritical fluids.

Comparing the Atmospheric Responses to Reduced Arctic Sea Ice, a Warmer Ocean, and Increased CO2 and Their Contributions to Projected Change at 2°C Global Warming

Abstract We consider the combined and individual influences of Arctic sea ice loss, sea surface temperature (SST) warming, and the direct radiative effect of increased CO2 on the Northern Hemispheric climate. The surface climate (e.g., temperature and precipitation) and atmospheric circulation responses (e.g., sea level pressure and wind) to these drivers are quantified using simulations from the Polar Amplification Model Intercomparison Project (for sea ice loss and SST warming) and the Cloud Feedback Model Intercomparison Project (for increased CO2). We verify the linear additivity of the PAMIP-derived winter responses to sea ice loss and SST change. The responses to SST change are of greater magnitude than that due to sea ice loss or due to CO2 direct radiative forcing in most seasons and regions, excluding the Arctic. Notably, however, sea ice loss is at least as important as SST change for the winter atmospheric circulation response over the North Atlantic and Siberia. The dynamical responses to sea ice loss and SST change oppose each other in many regions in winter, while the responses to SST and CO2 direct radiative forcing are often opposing in summer. Such opposing responses are less evident for the thermodynamical response. The sum of all three responses reproduces well the spatial patterns of change at 2°C global warming in winter and autumn in phase 6 of the Coupled Model Intercomparison Project projections but overestimates their magnitude.

Indian Ocean Intermediate Water Masses and Their Simulations by CMIP6 Models

Abstract Water masses are carriers of anthropogenic fingerprints in the ocean interior, with their property changes manifesting oceanic thermodynamic responses to climate change. Yet, delimiting ocean water masses remains challenging in either observational atlas or climate models. This study analyzes the distribution of Indian Ocean seawater in the density–spicity space and uses volumetric maxima and minima between σ = 27.1 and 27.4 kg m−3 to track the cores and boundaries of intermediate water masses, respectively. In addition to the well-known Antarctic Intermediate Water (AAIW) and Red Sea–Persian Gulf Intermediate Water (RS-PGIW), two other water masses are identified by the new approach. One is the Indian-AAIW (I-AAIW), as a mixture of the AAIW and the Indonesian Throughflow water, existing in the South Equatorial Current and the Agulhas Current system. The other [equatorial Indian Intermediate Water (EIIW)] exits in the equatorial Indian Ocean and Bay of Bengal, sourced from the RS-PGIW and overlying fresh waters. These waters are corroborated by nutrient and dissolved oxygen data. Around half (26 out of 51) of phase 6 of the Coupled Model Intercomparison Project (CMIP6) models can reasonably simulate these intermediate water masses. Compared with the observed water masses, the intermediate water masses in models are of a smaller thickness and the RS-PGIW is colder and fresher. The former arises from a warm bias in the thermocline, whereas the latter is likely linked to insufficient ventilation in the Red Sea and Persian Gulf in models owing to coarse grid resolution and a surface cold bias. Significance Statement Oceanic water masses are important for understanding climate change. Yet, the definition of water masses is controversial. Here, we use volumetric minima in the density–spicity space to track the boundaries of intermediate (27.1–27.4 kg m−3) water masses in the Indian Ocean. We identify four water masses: AAIW, I-AAIW, EIIW, and RS-PGIW. We delineate the geographical location of each water mass, including two newly identified water masses (I-AAIW and EIIW). We also examined the performance of 51 CMIP6 models in simulating these water masses and found that 26 models can reasonably simulate the distribution of these water masses. There are two systematic model biases emerging from these models. The intermediate water masses in models are of a thinner thickness arising from a warm bias in the thermocline, and the RS-PGIW is colder and fresher owing to insufficient ventilation in the Red Sea and Persian Gulf. These results provide a useful benchmark for understanding water masses in a changing climate and constraining climate models.

Probing the opto-electronic, thermoelectric, thermodynamic and elastic responses of lead-free double perovskite Li2ATlCl6 (A = Na and K) for potential photovoltaic and high- energy applications: A DFT study

The physical properties of double halide perovskite Li2ATlCl6 (A = Na and K) were examined through a first-principles study and semi-classical Boltzmann theory using the WEIN2k package, focusing on renewable energy generation and solar cell applications. Research on halides is growing within the optoelectronics and thermoelectric field and is anticipated to meet energy shortage demands. The volume-energy diagram confirms their structural stability, while the Pugh and Poisson ratios suggest ductility based on their elastic properties. The electronic properties were analyzed, and bandgaps were calculated using modified Becke-Johnson (mBJ) potentials, yielding bandgaps of 3.51 eV and 2.97 eV for Li2ATlCl6 (A = Na and K) respectively. The optical properties, evaluated using complex dielectric functions, indicated optimal light absorption in the infrared (IR) regions. Additionally, the thermoelectric (TE) properties of Li2ATlCl6 (A = Na and K) were analyzed using semi classical Boltzmann theory with a constant relaxation time approximation. At 1200 K, the calculated figures of merit (ZT) values were 0.75 and 0.69, respectively, indicating their potential for thermoelectric applications. Also, the thermodynamic properties are computed under pressure (0–15 GPa) and temperature (0–1200 K). These investigations offer a profound comprehension of these materials for their further employment. These results highlight their potential for optoelectronic device applications and are expected to encourage further experimental research on the feasibility of Li2ATlCl6 (A = Na and K) for optical devices.

Upper Ocean Thermodynamic Response to Coupling Currents to Wind Stress over the Gulf Stream

We use high-resolution coupled atmosphere–ocean model simulations over the Gulf Stream extension region during a winter season to examine the upper ocean thermodynamic response to including current feedback to atmospheric wind stress. We demonstrate that a model that includes current feedback leads to significant changes in the structure and transport of heat throughout the upper ocean in comparison to the same model without current feedback. We find that including the current feedback leads to changes in the upper ocean temperature pattern that match the vorticity pattern. Areas with cyclonic ocean vorticity, typically north of the Gulf Stream extension, correspond to areas with warmer temperatures throughout the water column. Areas with anticyclonic ocean vorticity, typically south of the Gulf Stream extension, correspond to areas with cooler temperatures throughout the water column. We also find that including current feedback leads to an overall reduction in the submesoscale vertical heat flux spectra across all spatial scales, with differences in the submesoscale vertical heat flux corresponding to SST minus mixed layer temperature differences. The direct impact of current feedback on the thermodynamic structure within the upper ocean also has indirect impacts on other aspects of the ocean, such as the energy transfer between the ocean and the atmosphere, ocean stratification, and acoustic parameters.

Response of Foldable Protein Conformations to Non-Physiological Perturbations: Interplay of Thermal Factors and Confinement.

Technological advances frequently interface biomolecules with nanomaterials at non-physiological conditions, necessitating response characterization of key processes. Similar encounters are expected in cellular contexts. We report in silico investigations of the response of diverse protein conformational states to lowering of temperature and imposition of spatial constraints. Conformational states are represented by folded form of the Albumin binding domain (ABD) protein, its compact denatured form, and structurally disordered nascent folding elements. Data from extensive simulations are evaluated to elicit structural, thermodynamic and dynamic responses of the states and their associated environment. Analyses reveal alterations to folding propensity with reduced thermal energy and confinement, with signatures of trend reversal in highly disordered states. Across temperatures, confinement has restrictive effects on volume and energetic fluctuations, leading to narrowing of differences in isothermal compressibility (κ) and heat capacities (Cp). While excess (over ideal gas) entropy of the hydration layer marks dependence on the conformational state at bulk, confinement triggers erasure of differences. These observations are largely consistent with timescales of protein-water hydrogen bonding dynamics. The results implicate multi-factorial associations within a simple bio-nano complex. We expect the current study to motivate investigations of more biologically relevant interfaces towards mechanistic understanding and potential applications.

Response of the upper ocean to northeast Pacific atmospheric rivers under climate change

Atmospheric rivers are important transport vehicles for Earth’s water cycle. Using a high-resolution, eddy-resolving Earth System Model, atmospheric river impacts on the upper ocean are investigated by analyzing historical and climate change simulations. For atmospheric rivers along the North American coastline, strong winds cause significant dynamic and thermodynamic upper ocean responses. They push ocean water towards the coast, measured by sea surface height, a process that is amplified under climate change. Mixed layers are deeper upstream of atmospheric rivers, and shallower downstream, however for climate change, shoaling downstream is subdued. Air-sea heat fluxes tend to promote ocean cooling upstream and warming downstream, although different regions have different climate change heat flux signals. Southern California heat flux changes due to warming are driven by evaporative processes and strengthen the ocean responses seen in historical simulations. The regions north are primarily dominated by sensible heat flux changes and counter the historical patterns.

A comprehensive DFT Study of the electronic structure and optical properties of Iodine-based halide double perovskites for photovoltaic applications

This study aims to explore the electronic structure, thermodynamic, mechanical stability, and optical response of Iodine-based ordered vacancy double halide perovskite compounds through the application of density functional theory. The two compounds Cs2ZrI6 and Rb2ZrI6 exhibit thermodynamic stability, with displaying particularly notable. Moreover, analysis of the calculated coefficients of elastic stiffness confirms the mechanical stability of all materials under ambient pressure conditions. By using the Density Functional Theory with Spin-Orbit Coupling (SOC), it was observed that Cs2TeI6 and Rb2TeI6 possess an indirect band gap located between the X and L high-symmetry points, this show that Cs2TeI6, Rb2ZrI6, Cs2HfI6, and Rb2HfI6 are identified as direct semiconductor compounds. Moreover, the band gap values of X2YI6 (where X = Cs, Rb, and Y = Te, Zr, and Hf) exhibit an increasing trend as we progress along the alkali and transition metal elements in the periodic table, ranging from 1.422 eV for Cs2TeI6 to 2.465 eV for Rb2TeI6. Besides, the optical behavior of the visible light show that X2YI6 compounds have a high absorption of about 70%, reflectance of 30%, and a low transmittance. Thanks to their advantageous bandgap, enduring stabilities, and effective absorption of visible light, Cs2TeI6 and Rb2TeI6 hold significant promise for a wide range of electronic and optoelectronic applications, particularly in photovoltaics.

Evidence for large thermodynamic signatures of in-gap fermionic quasiparticle states in a Kondo insulator

The mixed-valence compound YbB12 displays paradoxical quantum oscillations in electrical resistivity and magnetic torque in a regime with a well-developed insulating charge gap and in the absence of an electronic Fermi surface. However, signatures of such unusual fermionic quasiparticles in other bulk thermodynamic observables have been missing. Here we report the observation of a series of sharp double-peak features in the specific heat as a function of the magnetic field. The measured Hall resistivity evolves smoothly across the field values at which the characteristic anomalies appear in the thermodynamic response and rules out the possibility of conventional electrons as their origin. Our observations of thermodynamic anomalies in a bulk three-dimensional electrical insulator provide the evidence for the presence of emergent dispersing fermionic excitations within the insulating bulk, which sets the stage for further investigation of electron fractionalization in other correlated mixed-valence compounds.

Robust future intensification of winter precipitation over the United States

We investigate 21st-century hydroclimate changes over the United States (US) during winter and the sources of projection uncertainty under three emission scenarios (SSP2–4.5, SSP3–7.0, and SSP5–8.5) using CMIP6 models. Our study reveals a robust intensification of winter precipitation across the US, except in the Southern Great Plains, where changes are very small. By the end of the 21st century, winter precipitation is projected to increase by about 2–5% K−1 over most of the US. The frequency of very wet winters is also expected to increase, with 6–7 out of 30 winters exceeding the very wet threshold under the different scenarios. Our results suggest that the enhancement of future winter precipitation is modulated largely by coupled dynamic and thermodynamic responses, though partly offset by thermodynamic responses. Overall, our results highlight a high likelihood of increasing impacts from winter precipitation due to climate change.

Constitutive model for shape memory polymer and its thermodynamic responses in finite element analysis.

As a new intelligent polymer material, shape memory polymer (SMP) was a potential orthodontic appliance material. This study aimed to investigate the thermodynamic responses of SMP under different loads via finite element analysis (FEA). FEA specimens with a specification of 0.1 × 0.1 × 1 mm were designed. One end of the specimen was fixed, and the other was subjected to displacement load. Different loading, cooling, and heating rates were separately exerted on the specimen in its shape recovery process and used to observe the responses of the SMP constitutive model. Furthermore, specimens with various tensile elongation and sectional areas were simulated and used to elucidate their effect on shape recovering force. The specimens obtained a similar stress of 0.5, 0.44, and 1.07 Mpa for different loading, cooling, and heating rates after a long time. The shape recovering force of specimen increased from 0.0102 to 0.0315 N when the elongation improved from 10% to 40% and to 0.0408 N when the sectional areas were expanded to 0.2 × 0.2 mm. The stiffness of SMP was small at a high temperature but large at a low temperature. The effects of the loading, cooling, and heating rates on SMP can be eliminated after a long time. Furthermore, it was possible to increase the recovering force by increasing the elongation or expanding the sectional area of the specimen. The force was quadratically dependent on the elongation ratio.

On the Solute-Induced Structure-Making/Breaking Phenomena: Myths, Verities, and Misuses in Solvation Thermodynamics

We review the statistical mechanic foundations of the fundamental structure-making/breaking functions, leading to the rigorous description of the solute-induced perturbation of the solvent environment for the understanding of the solvation process of any species regardless of the type and nature of the solute–solvent interactions. Then, we highlight how these functions are linked to unambiguous thermodynamic responses resulting from changes in state conditions, composition, and solute–solvent intermolecular interaction asymmetries. Finally, we identify and illustrate the pitfalls behind the use of surrogate approaches to structure-making/breaking markers, including those based on Jones–Dole’s B-coefficient and Hepler’s isobaric-thermal expansivity, while highlighting their ambiguities and lack of consistency and the sources of misinterpretations.

Thermal Property Estimation of Thin-Layered Structures by Means of Thermoreflectance Measurement and Network Identification by Deconvolution Algorithm

Abstract Laser-induced forward transfer (LIFT) is a powerful tool for micro and nanoscale digital printing of metals for electronic packaging. In the metal LIFT process, the donor thin metal film is propelled to the receiving substrate and deposited on it. Morphology of the deposited metal varies with the thermodynamic responses of the donor thin film during and after the laser heating. Thus, the thermophysical properties of the multilayered donor sample are important to predict the LIFT process accurately. Here, we investigated thermophysical properties of a 100 nm-thick gold coated on 0.5 mm-thick sapphire and silicon substrates by means of the nanosecond time-domain thermoreflectance (ns-TDTR) analyzed by the network identification by deconvolution (NID) algorithm, which does not require numerical simulation or analytical solution. The NID algorithm enabled us to extract the thermal time constants of the sample from the nanosecond thermal decay of the sample surface. Furthermore, the cumulative and differential structure functions allowed us to investigate the heat flow path, giving the interfacial thermal resistance and the thermal conductivity of the substrate. After calibration of the NID algorithm using the thermal conductivity of the sapphire, the thermal conductivity of the silicon was determined to be 107–151 W/(m K), which is in good agreement with the widely accepted range of 110–148 W/(m K). Our study shows the feasibility of the structure function obtained from the single-shot TDTR experiments for thermal property estimation in laser processing and electronics packaging applications.

Thermodynamic analysis and equilibration response time prediction of recuperator in the SCO2 Brayton cycle

The recuperator of supercritical carbon dioxide (SCO2) Brayton cycle significantly affects the system's flexible control due to its thermal inertia. In this study, the structural parameters and operating parameters of recuperator are considered to quantitatively analyze the law of their influence on equilibration response time. Chebyshev spectrum method has been innovatively applied to the one-dimensional dynamic response model of recuperator. The dynamic response time of recuperator under the condition of temperature variation on the hot side is analyzed. The results show that reducing the thermal inertia of solid wall (by increasing the specific surface area of recuperator) can effectively decrease the equilibrium time. Additionally, the rate of inlet temperature variation should not be too large to reduce the thermal inertia of fluid. The zigzag channel demonstrates better dynamic response characteristic than straight channel. A novel dimensionless formula, based on structure and operating parameters, is proposed to quantitatively characterize and predict the equilibrium time for both straight and zigzag channel, the error is within ±20 %. Moreover, a high-precision neural network is trained to predict the equilibrium time directly. The results provide significant theoretical and application support for alleviating the thermal inertia of PCHE and improving the flexibility of SCO2 system.

Multi-Doping Exploration of (Sb, Bi and Ba) by First Principles on Ordered Zn–Si–P Compounds as High-Performance Anodes for Next-Generation Li-Ion Batteries

Chalcopyrite ZnSiP2 has emerged as a promising anode material for next generation Li-ion-based batteries due to its high theoretical capacity. First principles multiple-dopant effect computations were made on the structural, electronic, magnetic, and thermodynamic responses for chalcopyrite ZnSiP2(1−x)Sbx, ZnSiP2(1−x)Bix, Zn(1−x)BaxSiP2, and Zn1−xBaxSiP2(1−x)Sbx, using both the norm conserving, ultra-soft pseudopotentials with generalized gradient approximation (GGA+PBE) and the main frame of density functional theory. Lattice coefficient volume, bulk modulus, formation energy, and total energy of host materials were computed and compared with experimental and theoretical results. Energy band gap for the pure chalcopyrite ZnSiP2 system (1.4 eV) matches previous data and validates the accuracy of current calculations as doping concentration (x = 0.6, 0.9, and 0.12) of (Sb, Bi, and Ba) at Zn and P sites increases. The corresponding band gap decreases, resulting in greater enhancement in electronic conductivity. Finally, the phonon dispersion relation, phonon density of states, vibration frequencies of phonon, Gibbs free energy, enthalpy, entropy effect, and Debye temperature (θ D) were estimated to confirm the thermodynamic stability of both pure and doped systems. These investigations are predicted to contribute a deeper sympathy of the doping effects on ZnSiP2, facilitating further advancements in anode materials design for Li-ion batteries.

The thermodynamic response of heating at coronal null points

ABSTRACT Magnetic null points are an important aspect of the magnetic field structure of the solar corona and can be sites of enhanced dissipation. This paper uses analytical and numerical models to investigate the plasma structure around a heated null. It is shown that the temperature profile not only differs significantly from that in a uniform field, but also that the profile depends significantly on the spatial structure of the heating. Field lines close to the separatrices and the null point have higher temperatures than a uniform field for the same heating input. The dependence of the results near the null on both the ratio of perpendicular to parallel conduction, and numerical resolution is also explored. The comparison between analytic and numerical solutions also provides a useful benchmark to compare MHD codes with anisotropic thermal conduction.

A coupled thermo-mechanical model for investigating cracking and failure of composite interbedded rock

Composite interbedded rock is a special geological phenomenon that occurs when layers of rock (beds) of a given lithology lie between or alternate with other layers of a different lithology. The thermal and mechanical properties of the composite interbedded rocks exhibit strong anisotropy. Studying the thermomechanical coupling properties of natural composite interbedded rocks using existing experimental techniques is challenging. A coupled thermo-mechanical composite interbedded rock model was developed based on Fourier's heat-conduction law and Newton's second law. The thermodynamic responses and biaxial mechanical properties of composite interbedded rocks with different interlayer angles under the coupling of initial stress and thermal loading were studied for the first time. The results indicate that the thermal stresses within the granite interlayers are higher than those within the sandstone interlayers. Throughout the thermal loading process, thermal cracking occurred primarily within the (stiffer) granite interlayers. The number of thermal cracks generated during the cooling process far exceeds that during heating; at 400 °C, the number of thermal cracks during cooling is more than 35 times that during heating. When the interlayer dip angle approaches 90° and is aligned with the major principal stress direction, the phenomenon of the “double peaks” and layered failure becomes more pronounced. Within the range of variables considered, the relative impact of the three variables on peak stress in composite interbedded rock is as follows, from greatest to least: interlayer angle, thermal shock temperature, and model size. The results and developed modeling methods will contribute to the management and optimization of future engineering geology projects.

The Thermodynamic Responses of FG Conical/Cylindrical/Annular Panels with Circumferentially Variable Dimensions

This paper is the first to develop a meshless thermodynamic model with circumferentially variable dimensions to analyze the thermal-vibration mechanisms of typical functionally graded (FG) panel-type structures, mainly including conical, cylindrical, and annular panels. The longitudinal variation of the panel-type structure’s circumferential dimensions is taken into account according to specific rules. The Thin Plate Inverse Mapping (TPIM) meshless shape functions are introduced to characterize the displacement components associated with each substructure. Thermodynamic equations are formulated based on FSDT thermo-elastic theory as well as Hamilton’s principle. Rectangular and exponential pulse loads are taken into consideration for forced vibration analysis in this formulation. Numerical convergence and comparative cases are provided. Solutions from the literature and finite element simulation results are utilized for comparison, revealing that the percentage differences observed are all less than 0.025%. This confirms the reliability and accuracy of the developed analysis model. In conclusion, a detailed investigation is conducted on the influences of geometrical dimensions, boundary conditions, as well as thermal and external loads on the thermodynamic behaviors of FG panel-type structures with circumferentially variable dimensions.

A Study on the Thermodynamic Response of Double-Armed Thin-Walled Piers under an FRP Anti-Collision Floating Pontoon Fire

Abstract: As a potential fire scenario for bridge structures, the safety impact of an FRP anti-collision floating pontoon fire on bridge structures cannot be ignored. Taking the FRP anti-collision floating pontoon fire that occurred in a continuous rigid-frame bridge as the engineering background, the damage condition of the actual bridge fire scene was first investigated. In addition, FDS 5.3 software was used to simulate the FRP anti-collision floating pontoon fire scenario. Furthermore, the thermal–structural coupling method was used to investigate the thermodynamic response of double-armed thin-walled piers under fire. The results show that the FRP anti-collision floating pontoon fire causes localized concrete carbonization and spalling on the surface of the P2 pier, and the FRP anti-collision floating pontoons are largely destroyed. The fire has the greatest impact on the P2-1 pier, with the highest temperature of 667 °C on the windward side and the highest temperature of 326 °C on the leeward side. The temperature impact range is 6 m above the bearing platform, and the maximum damage depth of pier body concrete is 84.58 mm. The deformation and stress of the P2 pier under fire do not show significant changes and do not exceed the allowable limits for structural deformation and material stress. Therefore, the impact of this fire accident on the structural safety of the continuous rigid-frame bridge is minor. This study's results provide reliable guidance for the fire safety assessment and post-fire structural repair of the continuous rigid-frame bridge.