Search Results (1,538)

Background: Bronchoscopic thermal ablation has emerged as a minimally invasive therapeutic option for managing pulmonary nodules in patients unsuitable for surgery or radiotherapy. Robotic-assisted bronchoscopy (RAB) offers enhanced stability and precise navigation, potentially improving the safety and accuracy of bronchoscopic ablation. However, clinical data on RAB-guided microwave ablation (MWA) remains limited. Therefore, further evidence is needed to evaluate its feasibility, safety, and early therapeutic performance. Methods: We conducted a single-center retrospective feasibility study of shape-sensing RAB-guided MWA (ssRAB-MWA) for pulmonary nodules between October 2024 and September 2025. Eligible lesions (≤3.0 cm) included both primary lung cancers and metastatic nodules. All procedures were performed under general anesthesia using the ssRAB system integrated with cone-beam CT for intra-procedural confirmation. Technical success, safety outcomes, and short-term efficacy were assessed. Results: Nine patients (with 11 lesions: 3 primary, 8 metastatic) underwent ssRAB-MWA with 100% technical success. The median ablation time per nodule was 10 min (range, 1–26). One patient developed post-ablation pneumonia requiring hospitalization; no pneumothorax, major bleeding, or airway injury occurred. All lesions exhibited a transient increase in size immediately following MWA, followed by gradual reduction or stabilization over time. PET-CT evaluation demonstrated metabolic remission in primary lesions, with one patient achieving pathologic complete response after surgery. Conclusions: ssRAB-MWA appears to be a feasible and safe navigation-guided technique for small pulmonary lesions, offering encouraging early local control in both primary and metastatic lung cancers. This platform may expand the therapeutic spectrum of interventional pulmonology, bridging diagnosis and local therapy. Larger multicenter studies are warranted to validate long-term outcomes. Full article

This paper presents a side-by-side study of CFD predictions and experimental measurements for a novel counter-flow heat exchanger installed in the sidewall of a dishwasher (HEBS). The work aims to improve appliance efficiency by transferring heat from discharged hot wastewater to the incoming cold supply. Motivated by sustainability goals and tightening EU energy rules, the research targets the high losses typical of conventional machines. This approach combines detailed ANSYS Fluent 2022R2 simulations with controlled laboratory tests on a bespoke test rig. The measured data show a repeatable rise in the cold-water temperature of roughly 8 K, corresponding to an approximate 15% gain in thermal performance for the heat-recovery stage. While the simulations and experiments efficiently agree based on trends and qualitative behavior, there are noticeable quantitative differences in the total energy transfer, indicating the models need further refinement. The validation carried out here forms a solid basis for design optimization and for reducing energy consumption in household dishwashers. This work overcomes the limitations of previous studies which typically rely on external storage tanks or static heat recovery analysis. The primary novelty of this paper lies in the empirical validation of a high-efficiency heat exchanger integrated into the extremely constrained sidewall volume of the appliance, tested under transient, on-the-fly flow conditions, providing a verified methodology for constrained industrial applications. Full article

Heat exposure in summer increases the risk of heat strain during work and rest, highlighting the need for effective cooling strategies. This study evaluated the cooling effectiveness of a fan-cooling jacket (FC) and a thermoelectric neck cooler (NC) under resting conditions in a hot and humid environment. Six healthy males completed three trials (no cooling, FC, and NC) in an environmental chamber (35 °C, 70% RH). Thermophysiological responses (mean skin temperature, armpit temperature, sweat volume) and psychological ratings (thermal comfort, wetness sensation) were simultaneously assessed. FC significantly reduced mean skin temperature, attenuated the rise in axillary temperature, and decreased sweat volume while also improving thermal comfort and wetness sensation. In contrast, NC provided only transient improvements in comfort and did not suppress the rise in axillary temperature; wetness sensation deteriorated over time, likely due to its localized and limited cooling area. These findings indicate that, under low-activity conditions, broad-area forced convection cooling is more effective for mitigating heat stress than localized neck cooling. The results highlight the practical utility of fan-cooling garments for rest periods and other low-intensity scenarios. Full article

Modeling elementary diffusion processes in nanostructured materials is essential for developing platforms capable of interacting with high-speed physical signals. In this work, the photothermal response of a nano-hydroxyapatite/carbon nanotube (nHAp/CNT) composite was experimentally characterized and modeled through a cellular automaton (CA) framework designed to capture the thermal propagation of the hybrid system. Synthesizing nHAp/CNT composites enables the combination of the biocompatible and piezoelectric nature of nHAp with the enhanced photothermal response introduced by CNTs. UV–Vis reflectance measurements confirmed that CNT incorporation increases the optical absorption of the ceramic matrix, resulting in more efficient photothermal conversion. The composite was irradiated with a nanosecond pulsed laser, and the resulting thermal transients were compared with CA simulations based on a D2Q9 lattice configuration. The model accurately reproduces experiments, achieving R² > 0.991 and NRMSE below 2.4% for all tested laser powers. This strong correspondence validates the CA approach for predicting spatiotemporal heat diffusion in heterogeneous nanostructured composites. Furthermore, the model revealed a sensitive thermal coupling when two heat sources were considered, indicating synergistic enhancement of local temperature fields. These findings demonstrate both the effective integration of CNTs within the nHAp matrix and the capability of CA-based modeling to describe their photothermal behavior. Overall, this study establishes a computational–experimental basis for designing controlled thermal-wave propagation and guiding future multi-frequency or multi-source photothermal mixing experiments. Full article

The Finite Element Method is an indispensable tool for analyzing the transient thermal phenomena in welding processes. This study aims to simulate the temperature field during Gas Metal Arc Welding of an AISI 304L V-groove butt joint, employing a volumetric heat source model. The numerical simulations were conducted using ABAQUS SIMULIA^® (version 6.11-3) on a plate measuring 200 mm × 50 mm × 9.5 mm. For validation, the numerical results were compared against experimental data obtained at the Welding Engineering Research Laboratory of Federal University of Rio Grande. A parametric study was performed by varying the geometric parameter b (controlling the volumetric heat distribution depth) to enhance the model’s accuracy and achieve the closest approximation to experimental observations. The calibrated volumetric source demonstrated high accuracy, yielding low percentage differences between predicted and experimental peak temperatures: 1.02%, 2.50%, and 4.44% at the 4 mm, 8 mm, and 12 mm thermocouple positions, respectively. Full article

In recent years, the use of high-power semiconductor devices has seen growing demand across various applications, including data centers, electric vehicles, and traction systems. However, increasing power densities may increase challenges in ensuring the reliability of devices, particularly under high surge currents. These surge events may result in excessive power dissipation and rapid temperature increases, leading to device performance degradation and potential failure. Therefore, accurate temperature estimation is critical. However, existing approaches in the literature are mostly oversimplified and constrained by static I–V characteristics, limiting their accuracy. To encounter these limitations, this article proposes a forward-voltage-based temperature evaluation methodology for high-power diodes subjected to 10 ms surge events. The proposed model integrates rated electrical parameters with thermal simulation data to enable the accurate estimation of dynamic slope resistance and forward voltage during transient surge operation. The proposed framework shows strong agreement with the experimental results and provides a reliable tool for surge capability assessment. This approach enhances device modeling accuracy under very-high-current stress and offers valuable insights for electro-thermal design and thermal management in next-generation power semiconductor devices. Full article

We propose and demonstrate a low-random-noise (RN) design for pixel-parallel single-slope ADCs (SS-ADCs), achieving 2.2 e-rms in a 3.24 µm pixel. In this paper, we discuss AC-based RN estimation with respect to the comparator bias current and a bandwidth-limiting capacitor in digital-pixel sensors (DPSs). RN is composed of thermal noise (TN) and flicker noise (FN), where FN can be a major contributor in DPSs because of its area limitation. We express the concise equation to estimate the FN/TN ratio, in which the FN characteristic is modulated by the correlated double sampling (CDS) operation. We also study the effective RN bandwidth, which increases due to the ramp slope transient effect and introduces a noise bandwidth (NBW) coefficient, to estimate the effective NBW. This study provides insights into the area arrangement of the small-pixel DPS design. A high-gain single-ended comparator is introduced to realize an area-efficient DPS without digital CDS (D-CDS). Noise analysis of its pixel design shows that FN becomes the main contributor, and further RN improvement by limiting NBW or D-CDS is not promising under these conditions. Full article

A modified Enzyme Action Optimizer (mEAO) is proposed to tune a Fractional-Order Proportional–Integral–Derivative (FOPID) controller for precise temperature regulation of a nonlinear continuous stirred tank reactor (CSTR). The nonlinear reactor model, adopted from a standard benchmark formulation widely used in CSTR control studies, is employed as the simulation reference. The tuning framework operates in a simulation-based manner, as the optimizer relies solely on the time-domain responses to evaluate a composite cost function combining overshoot, settling time, rise time, and steady-state error. Comparative simulations involving EAO, Starfish Optimization Algorithm (SFOA), Success History-based Adaptive Differential Evolution with Linear population size reduction (L-SHADE), and Particle Swarm Optimization (PSO) demonstrate that the proposed mEAO achieves the lowest cost value, the fastest convergence, and superior transient performance. Further comparisons with classical tuning methods, Rovira 2DOF-PID, Ziegler–Nichols PID, and Cohen–Coon PI, confirm improved tracking accuracy and smoother actuator behavior. Robustness analyses under varying set-points, feed-temperature disturbances, and measurement noise confirm stable temperature regulation without retuning. These findings demonstrate that the mEAO-based FOPID controller provides an efficient and reliable optimization framework for a nonlinear thermal-process control, with strong potential for future real-time and multi-reactor applications. Full article

Transient safety analysis is a critical aspect of ensuring the safe design of Liquid Metal-cooled Fast Reactors (LMRs), relying heavily on advanced system analysis programs. To this end, the China Institute of Atomic Energy (CIAE) independently developed the Fast Reactor Transient Analysis Code (FRTAC) system analysis code for LMRs, which has been applied to the safety analysis of several reactor types. However, long-term use has revealed certain limitations, such as complex control system modeling and numerical dissipation from the first-order numerical scheme. This study analyzes the current limitations of the code and carries out systematic improvements and validation. The main improvements include enhancing the system compilation architecture and refactoring functional modules to improve computational efficiency, scalability, and usability; introducing a second-order accurate numerical scheme based on a limiter to reduce numerical dissipation in the convection term while ensuring computational stability; and optimizing the solution procedure to accommodate the new architecture and algorithms. The improved code’s computational stability and accuracy were validated using the Edwards blowdown experiment and the Energy Technology Engineering Center (ETEC) once-through steam generator steady-state test, respectively. The validation results show that the improved code maintains excellent numerical stability in problems with rapid transient pressure changes. In steady-state convective heat transfer problems, the computational accuracy and grid convergence are significantly improved, with the relative deviation of the water-side outlet temperature reduced from −3.56% to −0.59%. Under the same computational conditions, the computational efficiency was increased by up to 36.1%. The results of this study will provide a more accurate and efficient system analysis code for the transient safety analysis of LMRs. Full article

Cosmological scenarios wherein the cumulative number of spontaneously formed, cognitively impaired, disembodied transient observers is vastly larger than the corresponding number of atypical ‘ordinary observers’ (OOs) formed in the conventional way—essentially via cosmic evolution and gravitational instability—are disqualified in modern cosmology on the grounds of Cognitive Instability—the untrustworsiness of one own’s reasoning—let alone the atypicality of OOs like us. According to the concordance ΛCDM cosmological model—when described in the (expanding) ‘cosmic frame’—the cosmological expansion is future-eternal. In this frame we are atypical OOs, which are vastly outnumbered by typical Boltzmann Brains (BBs) that spontaneously form via sheer thermal fluctuations in the future-eternal asymptotic de Sitter spacetime. In the case that dark energy (DE) ultimately decays, the cumulative number of transient ‘Freak Observers’ (FOs) formed and destroyed spontaneously by virtue of the quantum uncertainty principle ultimately overwhelms that of OOs. Either possibility is unacceptable. We argue that these unsettling conclusions are artifacts of employing the (default) cosmic frame description in which space expands. When analyzed in the comoving frame, OOs overwhelmingly outnumber both BBs and FOs. This suggests that the dual comoving description is the cognitively stable preferred framework for describing our evolving Universe. In this frame, space is globally static, masses monotonically increase, and the space describing gravitationally bounded objects monotonically contracts. Full article

Short-time thermal exchange (0–20 s) between human skin and textile surfaces determines initial warm–cool sensations, which influences comfort perception. Classical Fourier models predicting a √t cannot fully describe this early transient phase, particularly for porous or heterogeneous materials such as fabrics. This study investigates the early and short-time temperature response of a fingertip to contact with eight woven and knitted fabrics of different compositions, densities, thermal resistances, and thicknesses, measured under controlled laboratory conditions using a fine-gauge thermocouple at the skin–fabric interface. Experimental temperature–time data, when converted to the Laplace domain, exhibited slopes corresponding to time-domain exponents of t^⅙, t^¼, and occasionally t^⅒, all lower than the classical diffusion exponent of ½.The dual-phase lag (DPL) model was applied to interpret these deviations through two lag times—τq (heat flux) and τT (temperature gradient)—and their ratio Z = τT/τq, which controls the slope of the Laplace-domain response. DPL curves reproduced the observed exponents without additional empirical parameters. The results show that short-time heat transfer depends strongly on textile structure: higher thickness leads to slower transient responses (“warmer” feel), whereas denser fabrics promote faster equilibration (“cooler” feel). This dual-phase interpretation bridges physical heat transfer with tactile thermal perception, providing a predictive framework for the design of textiles with thermal properties. Full article

Heat hardening induces complex biochemical reprogramming that enhances thermal resilience in marine bivalves. Despite this technique’s promising results in marine animals, the molecular basis of heat hardening is far from understood. This study elucidates the molecular mechanisms underlying the hardening process in Mytilus galloprovincialis exposed to a 4-day sublethal heat treatment. Induction of hsf-1, hsp70, and hsp90 genes revealed the activation of the heat shock response and proteostasis machinery, ensuring proper protein folding and preventing oxidative and proteotoxic stress. Simultaneous upregulation of mitochondrial (atpase6, cox1, nadh) and glycolytic (pk, cs) genes reflects enhanced oxidative phosphorylation and glycolytic flux, maintaining ATP supply and metabolic flexibility under elevated temperatures. Increased hif-1α expression suggests transient hypoxia signaling, coordinating oxygen utilization with redox control. Reinforcement of antioxidant defenses, together with elevated autophagy-related transcription, denotes a shift toward oxidative stress mitigation and damaged organelle clearance. Balanced expression of pro- (bax) and anti-apoptotic (bcl-2) factors, along with nf-κb modulation, supports tight regulation of cell survival and inflammatory responses. These findings underscore a highly integrated biochemical network linking proteostasis, intermediary metabolism, redox balance, and antioxidant defense with cellular quality control, which together underpin the physiological plasticity of heat-hardened M. galloprovincialis, enhancing survival under transient thermal stress. Full article

Thermal elongation in high-speed motorized spindles constitutes a major source of machining error in five-axis machine tools, critically impacting machining precision. This study aims to develop and validate a cumulative thermal error compensation model for predicting spindle thermal elongation, subsequently enabling effective compensation via a dedicated control algorithm. Key thermal error factors, primarily spindle speed and cumulative thermal error, were identified through analysis. An innovative numerical prediction model incorporating these factors was established. Its performance was evaluated through experiments utilizing eddy-current displacement sensors for high-speed, high-precision thermal elongation measurement. The validation results demonstrated the model’s strong predictive capability: During spindle startup, prediction errors exhibited minor transients, stabilizing near zero once the operating speed was reached. Under dynamic speed changes, the maximum prediction error was only 1.28 μm, with the overall maximum residual error recorded at 2.04 μm. These findings confirm the model’s high accuracy. Furthermore, the model exhibits excellent generalization capability, delivering significant compensation effectiveness across diverse variable-speed operating conditions. This work successfully developed a highly accurate numerical model and a practical compensation strategy, significantly enhancing the positioning accuracy of high-speed spindles against thermal disturbances. The proposed approach offers substantial engineering utility for thermal error compensation in precision machining applications. Full article

This paper presents the results of research on the effect of temperature on damage processes occurring in power MOSFETs. The impact of changes in the activation energy of selected mechanisms initiating the damage process in power MOSFETs during continuous operation on their lifetime is analyzed. Computer analyses and experiments illustrating the effect of transistor switching frequency on time to failure are also conducted. The impact of the relationship between the transistor’s thermal time constants and its switching period on lifetime is assessed. The effect of the transistor’s switching frequency on its junction temperature swing and average value is also assessed. Recommendations for designers of systems using these transistors are formulated to improve their reliability. Full article

High-temperature superconductor (HTS) magnet systems, especially those designed for fusion reactors, require effective and reliable monitoring to avoid damaging anomalies. In tokamaks, some of the magnetic coils are time-dependent, which causes strain and large inductive voltages within the magnet, rendering detection of incipient quench challenging. Ionizing radiation can also create material defects and lead to non-uniform degradation of conductors. The resulting decrease in critical current uniformity across the magnet, along with manufacturing defects, such as failure of structural materials or cooling systems, can all potentially initiate a quench. HTS magnets have a lower normal zone propagation velocity than low-temperature superconductors, and this causes normal zones to be localized, increasing the risk of permanent damage. Fiber optic sensors have several qualities that are essential in fusion systems. Unlike traditional voltage-based sensors, fiber optic cables are immune to the large electromagnetic fields present. This study presents and validates a fiber optic interrogation technique for monitoring magnetic confinement fusion and other high-temperature superconducting magnet systems. Coherent-phase optical time domain reflectometry (OTDR) allows for the high sampling rates (tens of kHz) necessary to quickly detect and mitigate quench events over the long distances required to monitor fusion magnet systems. This technique was demonstrated to successfully detect localized thermal transients at cryogenic temperatures as low as 6 K. These outcomes were also demonstrated using fibers embedded in HTS magnet coils at 77 K, verifying the potential for this interrogation technique’s use for failure detection in HTS coils. Full article