As global temperatures rise, the demand for personal thermal management continues to increase. Conventional refrigeration systems such as heating, ventilation, and air conditioning (HVAC) are energy-intensive, as they cool entire rooms instead of delivering localized cooling for the occupants. Although personalized cooling solutions such as thermal management fabrics and thermoelectric refrigerators have been explored, many have remained low in performance or are too bulky and heavy for practical personal use. To address this issue, the present study proposes a hollow thermoelectric refrigerator as a personal thermal management device. To achieve a cold-side temperature drop of 4 degrees C which is equivalent to a cool sensation, this hollow refrigerator requires 68% less electrical power than a conventional thermoelectric refrigerator and is 33% lighter, making it a promising wearable alternative. These results demonstrate the potential of hollow thermoelectric refrigerators as efficient personal thermal management devices.

Realistic thermal feedback is essential for improving immersion in virtual and augmented reality (VR/AR) systems. However, conventional wearable thermal devices often fall short in replicating the subtle thermal sensations associated with real-object contact, largely owing to their oversimplified emphasis on temperature while overlooking the complex interplay between object thermal properties and human thermophysiology. In this study, we propose a bioheat-based thermal contact model that enables accurate thermal haptic reproduction, allowing users to distinguish between objects with identical surface temperatures. To validate the model, we conducted finite element simulations and controlled experiments using materials (wood and copper) maintained at the same temperature. The results indicate that both interfacial temperature and heat flux exhibit timedependent behavior and must be concurrently regulated to reproduce realistic thermal haptic feedback. Overall, this study establishes a comprehensive framework for developing wearable thermo-haptic systems capable of delivering lifelike thermal sensations in VR/AR and broader human-machine interface applications.

In the development of thermochromic microcapsules (TMs)-based adaptive thermal management coatings, photonic frameworks to advance energy-saving performances remain unexplored. This study presents a systematic investigation into the modification of dynamic solar reflectance of TM-based composite coatings by controlling their particle size distribution via centrifugation, followed by the experimental retrieval of bulk optical properties using the Inverse Adding-Doubling method. While smaller supernatant particles (TM-sup) achieved an enhanced solar reflectance compared to the as-purchased product (TM-pro), the larger sedimented particles (TM-sed) exhibited superior modulation. The size-directed dynamic optical properties of these materials have the potential to enhance energy-saving strategies across diverse climatic regions, as demonstrated by EnergyPlus simulations. Furthermore, it was determined that the particle number density, the scattering anisotropy, and the core-to-shell volume ratio collectively exerted a synergistic effect, inducing the size-directed modulations. Therefore, the present work establishes a physical framework for the photonic design of TM-based coatings. In addition, it identifies particle size as a critical pathway for optimizing high-performance thermo-responsive adaptive thermal management coatings.

The Seebeck coefficients of thermogalvanic (ionic thermoelectric) materials are several orders of magnitude greater than those of conventional thermoelectrics, making them highly suitable for sensing applications besides power generation. In this study, a ferri-/ferrocyanide thermogalvanic gel with a Seebeck coefficient of 1.3 mV K-1 was used to fabricate a heat flux sensor with fivefold higher sensitivity than the commercial FHF05 sensor. This device detected a human finger at distances of up to 8 cm using thermal radiation, a capability particularly relevant to human safety in collaborative robot environments. Coupled radiation-natural convection simulations in COMSOL closely matched experimental data, validating the proposed sensing mechanism. The high Seebeck coefficient of the material enabled sensitive heat-flux transduction, extending its functionality beyond single-point detection to spatially resolved thermal mapping. Capitalizing on this advantage, 16 gels were integrated into a compact 3 cm-scale 4 & times; 4 sensor array. Upon human finger contact, the array generated a heat flux map capturing both the intensity and spatial distribution of the thermal input. Overall, this capability allows the identification of nonuniform heat flux and enhances radiation detection.

To address the rise in industrial waste heat resulting from increasing global energy consumption, this study introduces a supporter-inserted trapezoidal thermoelectric device (SITTED) with a modified leg architecture. The SITTED features a trapezoidal leg incorporating a low-thermal-conductivity supporter, which increases the thermal resistance to more than twice that of conventional thermoelectric generators. This architecture delivers a 2.2-fold increase in the temperature difference between the hot and cold sides of the device and approximately doubles the power output relative to traditional designs. While prior research on Internet of Things (IoT)–integrated thermoelectric generators has predominantly focused on conceptual frameworks or small-scale laboratory evaluations, this study bridges the gap between laboratory prototypes and industrial applications through a complete systemization and full-scale field demonstration. The feasibility of the SITTED was verified by conducting a field experiment at a combined-cycle power plant, where the device, integrated with a topology-optimized heat sink that provided a 1.6-fold reduction in thermal resistance, could enable the operation of an IoT temperature sensing system without an external power supply for two weeks. These results underscore the potential of the proposed architecture for self-sustaining thermoelectric applications in industrial environments.

Metallic hydrogen storage and robust mechanical properties in superconductors may have critical importance in superconducting applications with liquid hydrogen cooling agent. Here, we investigate the superconducting and hydrogen storage functionalities in bulk TaNb2HfZrTi high-entropy alloys (HEAs) synthesized by mechanical alloying followed by hot-press sintering. The optimized superconducting sample (HP-900) exhibits a sharp superconducting transition at T c = 7.8 K, a high upper critical field mu 0 H c2(0) = 10.85 T, and a critical current density exceeding 2.9 x 105 A cm- 2 at 4 K, surpassing values reported for arc-melted and spark-plasma-sintered counterparts. Meanwhile, the HEA sample achieves an outstanding room-temperature hydrogen storage capacity (H/M = 2.23, 3.8 wt.% at 20 degrees C, 100 bar), which is high value corresponding to the state-of-the-art metallic high entropy alloy hydrides at room temperature. This unique integration of bulk processing, microstructural control, and dual functional performances establishes that the TaNb2HfZrTi can be a benchmark platform for multifunctional BCC high-entropy alloys, and it provides design principles for next-generation cryogenic and solid-state hydrogen technologies.

ABSTRACT Magnetism‐assisted transport is achieved in Mn‐containing SnSe magnetic nanocomposites, where superparamagnetic MnSe nanoprecipitates are introduced to modulate both carrier and phonon scattering. Transmission electron microscopy reveals well‐dispersed 5–10 nm MnSe inclusions embedded within the SnSe matrix. Magnetization measurements identify a blocking temperature of 165 K and temperature‐dependent hysteresis behavior consistent with Néel relaxation, confirming active s–d exchange between localized Mn moments and itinerant carriers. Compared to pristine SnSe, the composites exhibit an enhanced power factor alongside reduced total thermal conductivity. Integrated crystal‒orbital Hamilton population analysis reveals that Mn substitution weakens bonding, while phonon calculations indicate a decrease in group velocities; together, these effects account for the observed suppression in lattice thermal conductivity. The combined influence of spin‐fluctuation scattering and phonon softening results in a peak figure of merit ( zT ) of 1.98 at 820 K for Sn 0.97 Mn 0.03 Se. These findings demonstrate that integrating superparamagnetic dynamics with lattice softening enables decoupling of the Seebeck coefficient and electrical conductivity while simultaneously reducing thermal conductivity in earth‐abundant chalcogenides.

ABSTRACT Metallic hydrogen storage and robust mechanical properties in superconductors may have critical importance in superconducting applications with liquid hydrogen cooling agent. Here, we investigate the superconducting and hydrogen storage functionalities in bulk TaNb 2 HfZrTi high‐entropy alloys (HEAs) synthesized by mechanical alloying followed by hot‐press sintering. The optimized superconducting sample (HP‐900) exhibits a sharp superconducting transition at T c = 7.8 K, a high upper critical field µ 0 H c2 (0) = 10.85 T, and a critical current density exceeding 2.9 × 10 5 A cm − 2 at 4 K, surpassing values reported for arc‐melted and spark‐plasma‐sintered counterparts. Meanwhile, the HEA sample achieves an outstanding room‐temperature hydrogen storage capacity ( H/M = 2.23, 3.8 wt.% at 20°C, 100 bar), which is high value corresponding to the state‐of‐the‐art metallic high entropy alloy hydrides at room temperature. This unique integration of bulk processing, microstructural control, and dual functional performances establishes that the TaNb 2 HfZrTi can be a benchmark platform for multifunctional BCC high‐entropy alloys, and it provides design principles for next‐generation cryogenic and solid‐state hydrogen technologies.

Thermoelectric generators (TEGs) are gaining great attention as a promising technology for waste heat recovery due to their ability to directly convert heat into electricity. However, their relatively low conversion efficiency limits widespread adoption. While efficient thermal management of TEGs is crucial to achieve high conversion efficiencies, less attention has been paid to this aspect thus far compared to materials development. Efficient TEGs require efficient heat dissipation on the cold side of TEGs, demanding careful heat sink design. In this study, a topology optimization model was developed to design air-cooled heat sinks specifically for TEG applications, incorporating both thermoelectric properties and the geometric structure of TEGs. The optimized heat sink was fabricated using additive manufacturing, and its performance was experimentally validated. Compared to a conventional rectangular fin heat sink, the topology optimized (TO) heat sink significantly reduced thermal resistance across a wide range of pressure drops (6 Pa-30 Pa), achieving a 33.5 % reduction at a 12 Pa pressure drop. This led to a 44.7 % increase in the output power of a commercial TEG. Despite a similar to 40 % increase in power consumption, the TO heat sink resulted in a 21.3 % improvement in conversion efficiency. This improvement is equivalent to a 27 % increase in the device thermoelectric figure of merit (ZT). Numerical simulations revealed that the TO heat sink can enhance temperature uniformity on the cold side of the TEG, further contributing to performance gains. These findings highlight the effectiveness of heat sink topology optimization in enhancing the conversion efficiency of TEGs.

Thermochromic windows have been studied as a promising solution for energy-efficiency with the dynamical adjustment of solar heating in response to temperature. Recent advancements in the field have introduced simultaneous multiband modulation, incorporating radiative cooling in the longwave infrared range. In this work, we present VO2(M)/TiO2(A)/ITO multilayer-coated glass (referred to as VTI) as a scalable and effective smart window that modulates both solar transmission and radiative cooling concurrently. As a semitransparent window in the solar spectrum, the VTI coating achieves nearly 100 % visual clarity, 38.5 % visible transparency, and 8.5 % modulation of solar transmittance. In the longwave infrared region, the VTI multilayer demonstrates an exceptional broadband emissivity shift of up to 42.5 %, made possible by an innovative Fabry-P & eacute;rot (F-P) cavity composed of absorbing metal oxides. This high degree of emissivity modulation is maintained across a wide range of spacer thicknesses, from 100 to 500 nm, as confirmed by both experimental data and simulations. The modulation mechanism of the F-P cavity which use ultrathin spacer (lambda/140 similar to lambda/16) at its resonant absorption range is explained through incremental phasor analysis by the transfer-matrix method. Additionally, the scalability and practicality of the VTI film are supported by its three-layer composition and the room-temperature reactive magnetron sputtering deposition process. These results suggest that the design principles presented here could inspire further innovations in broadband longwave infrared emissivity modulation, utilizing ultrathin F-P cavities composed of semitransparent metal oxides.

This study proposes effective thermal management solutions for vehicle-mounted active electronically scanned array (AESA) radar systems via the improvement of existing cooling systems and optimization of heat dissipation for T/R and SAM modules. Unlike previous studies that focused on coolant flow optimization, which often requires costly system modifications, this research suggests practical solutions that involve additional heat dissipation structures or optimized shapes for existing aluminum housings. The results of a numerical analysis shows that the application of these solutions reduces the maximum temperature of component C in the T/R module from 52.1 degrees C to 27.5 degrees C and 35.9 degrees C. The temperature deviation was also significantly reduced from 23 degrees C to 0.4 degrees C and 1.5 degrees C, thus improving cooling performance and reducing temperature variation by up to 85%.

Although thermoelectric systems offer advantages such as compactness, silent operation, absence of moving parts, and long-term reliability, their applicability is hindered by high power-generation costs ($/W). This study introduces hollow thermoelectric legs that achieve extremely low $/W while being compatible with existing scalable manufacturing processes. A sodium chloride rod was sintered together with thermoelectric materials and then dissolved to obtain the hollow structure. This unique structure enables reduced material consumption by 60 % (low $) as well as 230 % enhancement in power output (high W) leading to 83 % reduction in $/W over a conventional thermoelectric device with fully filled legs. The scalability of the manufacturing process for the proposed device was also verified by fabricating a thermoelectric module and evaluating its performance. The results achieved with the proposed device architecture highlight the potential for the commercialization of thermoelectric generators.

The escalating global energy demand and the need for sustainable energy solutions highlight the importance of advancing thermoelectric technologies for efficient waste heat recovery and refrigeration. Although diamondlike chalcogenides are promising high-performance thermoelectric materials, the development of high-efficiency n-type counterparts remains a major challenge. This study introduces a multi-doping approach to synthesize high-entropy diamond-like chalcogenides AgxCdyIn1-zZnzSe2, achieving an ultra-low lattice thermal conductivity of 0.2 W/m.K at 800 K in AgCd0.2In0.9Zn0.1Se2.This is attributed to the formation of Ag-rich nanoclusters and strong phonon scattering induced by lattice strain and point defects. In parallel, carrier concentration is optimized through excess Ag and multi-doping, which enhances the power factor. As a result, a peak zT of 1.15 at 800 K and an average zT of 0.82 over 370-800 K are achieved, which represents the highest reported values for n-type diamond-like chalcogenides within this temperature range. In addition, a prototype thermoelectric module was fabricated by combining the developed n-type AgCd0.2In0.9Zn0.1Se2 with p-type Cu0.8Ag0.2[Ga0.8In0.2]0.99Zn0.01Te2. These results demonstrate the potential of high-entropy diamond-like chalcogenides for next-generation thermoelectric applications while also underscoring the need for further optimization of module integration.

2D materials possess weak inter-layer van der Waals bonding, allowing them to exist as different polymorphs depending on the stacking sequence of the layers. Herein, the thermal conductivities of the 2H-NbSe2 and 2H-3R-NbSe2 polymorphs by conducting experimental measurements and theoretical analysis are comparatively studied. Owing to its 1.8 times larger unit cell, 2H-3R-NbSe2 has a considerably greater number of optical phonon branches than does 2H-NbSe2, suggesting that 2H-3R-NbSe2 absorbs thermal energy rather than transporting it. In addition, scattering is more likely to occur in 2H-3R-NbSe2 because a far greater number of states satisfy the selection rule. As a result of these, the 2H-3R-NbSe2 has considerably lower thermal conductivity than that of the 2H-NbSe2. The results highlight how the size of the unit cell affects the thermal conductivities of polymorphs.

Previous studies on temperature-controlled, multi-band smart windows have been limited, as they often lacked comprehensive evaluations of energy-saving performance or did not incorporate temperature-dependent optical properties. This study quantitatively evaluates the energy-saving performance of a thermochromic smart window using EnergyPlus software. We employ the characteristics of a VO2 (M)/TiO2 (A)/ITO (VTI) structure, an ultrathin absorptive Fabry-Perot resonator. This coating actively and simultaneously modulates solar transmittance by 8.5% and long-wave infrared emissivity by 0.43 in response to external temperature. By simulating annual heating and cooling loads for a single-story office building across five major climate zones, we demonstrate that this technology reduces a building's annual energy demand by up to 75% in regions with distinct seasonal fluctuations. These findings highlight the strong potential of dynamic, multi-band modulation as a key technology for developing high-efficiency, climate-adaptive building envelopes.

Abstract True random numbers are essential for ensuring information security and supporting simulations across various industries. With the exponential growth of data driven by advancements in artificial intelligence, robust encryption for communications has become increasingly important. While software‐based deterministic random number algorithms are cost‐effective and easy to use, they are vulnerable to attacks by powerful supercomputers, highlighting the need for more secure alternatives. As portable electronic devices and information‐gathering sensors proliferate, portable true random number generators (TRNGs) are critical for maintaining security. In this work, hybrid material‐based photodetectors composed of anionic polymers and perovskites that maximize stochastic photogeneration for TRNG applications are presented. By integrating perovskite photodetectors with simple electronic circuits, compact, low‐power TRNG devices have been developed that are versatile and resilient to environmental factors. These devices generate 10 000 bits s−1 without resets or delays, achieving significant miniaturization. The generated 10 Mbit random number is validated through US National Institute of Standards and Technology (NIST) testing. Using a 480 000‐bit random sequence, perfect image encryption, ensuring protection against hacking are demonstrated. Additionally, the perovskite TRNG can operate under external light even when embedded in pork skin, realizing its potential as an implantable device for personal security and authentication.

Control moment gyroscope (CMG), used for attitude control of spacecraft or satellites, requires thermal analysis to manage and optimize power consumption as it generally operates incessantly for the lifespan in extreme conditions of space. In this study, to more accurately calculate the stabilized temperature of the system, heat generation was applied as a boundary condition in a steady-state thermal analysis, represented as a function of the system and component temperatures. A simplified finite element method (FEM) model using a steady -state -based thermal resistance method were adopted to analyze the factors affecting the thermal stability of the system under extreme conditions at20 degrees C and 70 degrees C. At -20 degrees C, under the condition of a total heat dissipation of 28.22 W, the system exhibited a high maximum temperature rise of 43 degrees C on the motor PCB. At 70 degrees C, with a total heat dissipation of 7.2 W, the maximum temperature rise of the system was relatively low at 5.9 degrees C, occurring at the bearing. The results indicated that the temperature of the bearing component strongly influenced the heat dissipation in the system. The friction torque of the bearing, which is the most significant factor regarding heat dissipation and power consumption, was noted to be approximately 10 times higher at -20 degrees C than at 70 degrees C. Consequently, the heat dissipation from the bearing was approximately 4 times higher, whereas the heat dissipation from the motor was approximately 10 times higher at -20 degrees C than at 70 degrees C.

Although wearable devices for continuous monitoring of vital signs have undergone significant advancements, their need for frequent recharging precludes continuous operation, potentially leading to adverse outcomes being overlooked. Additionally, the scattered locations of the sensors hamper wearability. Herein, we present a compact vital-sensing band with uninterrupted power supply designed for continuous monitoring of core body temperature (CBT) and pulse rate. The band-which comprises two sensors, a power source (i.e., a flexible thermoelectric generator (TEG) and a battery), and a flexible circuit-is worn on the forearm. The CBT is calculated by measuring the skin temperature and heat flux, while a triboelectric nanogenerator-based self-powered pressure sensor is utilized for pulse rate monitoring. The TEG is a flexible unit that converts body heat into electricity, accumulating a total energy of 314 mJ (100%). Out of this total energy, only 43.2 mJ (7.2%) is utilized for CBT measurements, while the remaining 270.80 mJ (92.8%) is stored in the battery. This enables reliable and continuous operation of the vital-sensing band, highlighting its potential for use in healthcare applications.

Thermal barrier coatings(TBCs) are increasingly applied to turbine components to enhance performance. These coatings not only shield materials from high-temperature environments but also mitigate oxidation and corrosion. TBCs consist of a top coating and a bond coating. This study presents measurement methods and results for each TBC layer , analyzing the thermophysical properties through literature comparisons. The thickness of specimen coating layers was measured using digital calipers and scanning electron microscopy (SEM), while thermal diffusivity was measured using a laser flash apparatus(LFA). For the top coating deposited via electron-beam physical vapor deposition(EB-PVD), thermal diffusivity was approximately 50% higher compared to the coatings produced by atmospheric plasma spray(APS). Furthermore, the bond coating applied via APS exhibited approximately 10% lower thermal diffusivity compared to coatings deposited using vacuum plasma spray(VPS).