Search Results (67,059)

This paper deals with a privacy-preserving human tracking system that uses multi-property infrared sensor arrays. In the growing field of intelligent elderly care, there is a critical need for monitoring systems that ensure safety without compromising personal privacy. While traditional camera-based systems offer detailed activity recognition, privacy-related concerns often limit their practical application and user acceptance. Consequently, approaches that protect privacy at the sensor level have gained increasing attention. The privacy-preserving human tracking system proposed in this paper protects privacy at the sensor level by fusing data from an ultra-low-resolution $8\times 8$ (64-pixel) passive thermal infrared (IR) sensor array and a similarly low-resolution $8\times 8$ active Time-of-Flight (ToF) sensor. The thermal sensor identifies human presence based on heat signature, while the ToF sensor provides a depth map of the environment. By integrating these complementary modalities through a convolutional neural network (CNN) enhanced with a cross-attention mechanism, our system achieves real-time three-dimensional human tracking. Compared to previous methods using ultra-low-resolution IR sensors, which mostly only obtained two-dimensional coordinates, the acquisition of the Z coordinate enables the system to analyze changes in a person’s vertical position. This allows for the detection and differentiation of critical events such as falls, sitting, and lying down, which are ambiguous to 2D systems. With a demonstrated mean absolute error (MAE) of 0.172 m in indoor tracking, our system provides the data required for privacy-preserving Ambient Assisted Living (AAL) applications. Full article

Heat stress has emerged as a significant abiotic constraint affecting rice yield and grain quality. In recent years, substantial advancements have been achieved in elucidating molecular regulatory mechanisms and breeding applications pertinent to rice heat tolerance. This review offers a comprehensive examination of the fundamental regulatory pathways involved in rice responses to heat stress, encompassing membrane lipid homeostasis, heat signal transduction, transcriptional regulation, RNA stability and translation, epigenetic modifications, hormone signaling, antioxidant defense, and the protection of reproductive organs. Particular emphasis is placed on the functional mechanisms and breeding potential of pivotal thermotolerance-associated genes and quantitative trait loci (QTLs), such as TT1, TT3, and QT12. Additionally, we summarize recent applications of cutting-edge technologies in the enhancement of heat-tolerant rice varieties, including multi-omics integration, CRISPR/Cas9 genome editing, marker-assisted selection (MAS), and rational design breeding. Finally, we address current challenges, including integrating regulatory mechanisms, developing realistic heat simulation systems, validating the functionality of candidate genes, and managing trait trade-offs. This review provides a theoretical foundation for developing heat-tolerant rice cultivars and offers valuable insights to accelerate the breeding of climate-resilient rice varieties for sustainable production. Full article

As an eco-friendly natural building material, rammed earth possesses outstanding hygrothermal performance, which plays a vital role in achieving the goals of sustainable architecture. However, most existing simulations assume constant hygrothermal parameters, resulting in considerable discrepancies between predicted and actual energy performance and consequently underestimating the true passive regulatory potential of rammed earth. To enhance the accuracy of energy consumption predictions in rammed earth buildings, this study integrates experimental measurements with dynamic simulations and experimentally determines both the constant and non-constant hygrothermal parameters of rammed earth. By integrating experimental and simulation approaches, this study reveals a strong positive linear correlation between the thermal conductivity of rammed earth and its moisture content (R² = 0.9919), increasing from 0.77 W/(m·K) to 1.38 W/(m·K) as moisture content rises from 0% to 14%, whereas the moisture resistance factor decreases exponentially with increasing relative humidity (RH). Subsequently, the two sets of hygrothermal parameters were implemented in the WUFI-Plus simulation platform to conduct annual dynamic simulations across five representative Chinese climate zones (Harbin, Beijing, Nanjing, Guangzhou, and Dali), systematically comparing the performance differences between the “non-constant” and “constant” parameter models. The results show that the non-constant parameter model effectively captures the dynamic hygrothermal regulation of rammed earth, exhibiting superior passive performance. It predicts substantially lower building energy loads, with heating energy reductions most pronounced in Harbin and Beijing (16.9% and 15.5%) and cooling energy reductions most significant in Guangzhou and Nanjing (15.8% and 15.2%). This study confirms that accurately accounting for the dynamic hygrothermal coupling process is fundamental to reliably evaluating the performance of hygroscopic materials such as rammed earth, providing a robust scientific basis for promoting energy-efficient, low-carbon, and climate-responsive sustainable building design. Full article

Integrated additional cooling channels offer precise thermal management for solid-oxide fuel cells (SOFCs), mitigating temperature gradients. This research studies the thermal–hydraulic performance of cooling channels integrated between SOFC interconnectors, including a Diamond-type triply periodic minimal surface (TPMS), a conventional topology-optimized structure, and a topology-optimized lattice-filled structure. A conjugate heat transfer analysis is employed to investigate the influences of flow rate within the range of Reynolds numbers from 300 to 5000, and the effects of coolant type, including air and liquid metals, as well as the impacts of structural material. The results demonstrate that the topology-optimized lattice-filled structure, generating high turbulence mixing, achieves superior temperature uniformity, especially at high flow rates, despite having higher thermal resistance and pressure loss than the conventional topology-optimized design. The coolant types show the largest influence on thermal–hydraulic performance, and the use of liquid gallium in the conventional optimized design obtains the best temperature uniformity, yielding differences between the maximum and minimum temperatures of less than 5 K. Moreover, the higher-thermal-conductivity material improves temperature uniformity, even at low flow rates. Overall, the optimized-baffle designs in the conventional topology-optimized model, utilizing high-conductivity coolant and structural materials, could be the most suitable for thermal management of the SOFC. Full article

University campuses feature spatially diverse environments where thermal performance varies seasonally and spatially. In this study, we integrate field measurements with ENVI-met simulations to evaluate how sky view factor (SVF) influences microclimate and outdoor thermal comfort-quantified via air temperature (Ta), mean radiant temperature (Tmrt), wind speed (WS), relative humidity (RH), physiologically equivalent temperature (PET), and the Universal Thermal Climate Index (UTCI)-within urban street and urban building spaces on a temperate Chinese campus. The results reveal contrasting thermal responses: in summer, low-SVF urban street spaces (SVF_avg 0.075) exhibit moderate heat stress (PET_avg 34.5–39.5 °C) due to radiative trapping and limited ventilation, whereas high-SVF urban building spaces (SVF_avg 0.159) face greater heat load and stronger thermal stress, with peak PET exceeding 49.9 °C. In winter, high-SVF urban building spaces benefit from solar gain, improving thermal comfort. Statistical analyses indicate non-linear threshold effects of SVF on comfort indices, with summer comfort positively correlated at SVF > 0.2, and winter comfort negatively associated at SVF ≤ 0.4. These findings identify SVF as a key geometric predictor of seasonal thermal comfort in distinct campus spatial types, provide quantitative thresholds to guide climate-resilient campus planning in warm temperate zone. Full article

As a zero-carbon fuel, ammonia holds significant potential for achieving the “dual carbon” strategic goals. However, its extremely low laminar burning velocity (LBV) limits its direct application in combustion systems. This work systematically reviews the research progress on the LBV of ammonia flames, focusing on three key aspects: measurement methods, effects of combustion conditions, and reaction kinetic models. In terms of measurement methods, the principles, applicability, and limitations of the spherical outwardly propagating flame method, Bunsen-burner method, counter-flow flame method, and heat flux method are discussed in detail. It is pointed out that the heat flux method and counter-flow flame method are more suitable for the accurate measurement of ammonia flame LBV due to their low stretch rate and high stability. Regarding the effects of combustion conditions, the LBV characteristics of pure ammonia flames under ambient temperature and pressure are summarized. The influence patterns of three factors on LBV are analyzed systematically: blending high-reactivity fuels (e.g., hydrogen and methane), oxygen-enriched conditions, and variations in temperature and pressure. This analysis reveals effective approaches to improve ammonia combustion performance. Furthermore, the promoting effect of high-reactivity fuel blending on liquid ammonia combustion was also summarized. For reaction kinetic models, various chemical reaction mechanisms applicable to pure ammonia and ammonia-blended fuels (ammonia/hydrogen, ammonia/methane, etc.) are sorted out. The performance and discrepancies of each model in predicting LBV are evaluated. It is noted that current models still have significant uncertainties under specific conditions, such as high pressure and moderate blending ratios. This review aims to provide theoretical references and data support for the fundamental research and engineering application of ammonia combustion, promoting the development and application of ammonia as a clean fuel. Full article

Phase change materials (PCMs) integrated into building envelopes can store and release latent heat, reducing indoor temperature fluctuations and shifting thermal peaks. This study quantifies the time lag and comfort impact of PCM plaster under free-running conditions using two identical, instrumented model houses in Bácsalmás, Hungary. One house served as a reference, while the other was retrofitted with interior PCM plaster panels on four walls (51.2 kg paraffin, ≈8.12 MJ latent heat capacity). The temperatures of the walls, indoor air, and outdoor environment were monitored every five minutes for 105 spring/summer days. Daily peak times were extracted using moving-average smoothing, and time lags between exterior and interior wall peaks were computed. The PCM house exhibited roughly double the average lag compared with the reference (≈200 vs. ≈100 min), with lag distributions well described by lognormal fits. Comfort evaluation based on exceeded degree-hours (EDH) relative to the adaptive comfort range (EN 16798-1) revealed that larger peak-time lags correlated with lower overheating. Results confirm that PCM plaster significantly delays and attenuates daily temperature peaks, extends comfort periods, and supports passive strategies such as night ventilation and demand-side load shifting in lightweight buildings. Full article

Land surface temperature (LST) is a critical variable for understanding energy exchanges and water balance at the Earth's surface, as well as for calculating turbulent heat flux and long-wave radiation at the surface–atmosphere interface. Remote sensing techniques, particularly using satellite platforms like Landsat 8 OLI/TIRS and Sentinel-2A, have facilitated detailed LST mapping. Sentinel-2 offers high spatial and temporal resolution multispectral data, but it lacks thermal infrared bands, which Landsat 8 can provide a 30 m resolution with less frequent revisits compared to Sentinel-2. This study employs Sentinel-2 spectral indices as independent variables and Landsat 8-derived LST data as the target variable within a machine-learning framework, enabling LST prediction at a 10 m resolution. This method applies grid search-based hyperparameter-tuned machine learning algorithms—Random Forest (RF), Gradient Boosting Machine (GBM), Support Vector Machine (SVM), and k-Nearest Neighbours (kNN)—to model complex nonlinear relationships between the spectral indices (NDVI, NDWI, NDBI, and BSI) and LST. Grid search, combined with cross-validation, enhanced the model's prediction accuracy for both pre- and post-monsoon seasons. This approach surpasses earlier methods that either employed untuned models or failed to integrate Sentinel-2 data. This study demonstrates that capturing urban thermal dynamics at fine spatial and temporal scales, combined with tuned machine learning models, can enhance the capability of urban heat island monitoring, climate adaptation planning, and sustainable environmental management models. Full article

The growing importance of sustainable technologies and environmental safety is promoting the implementation of green chemistry principles in the field of energetic materials. Traditionally, nitrocellulose-based propellants are plasticized with dibutyl phthalate (DBP), which is classified as a hazardous substance due to its toxicity and migration during storage. In this work, triethyl 2-acetylcitrate (ATEC) and tributyl 2-acetylcitrate (ATBC) were investigated as biodegradable and non-toxic alternatives to DBP. The objective of this study was to evaluate the thermal and chemical stability, physicochemical properties, and incorporation efficiency of these eco-friendly plasticizers in regard to propellants prepared from nitrocellulose of different origins and with nitrogen contents. The stability of the obtained propellants was assessed based on accelerated aging tests conducted in accordance with NATO STANAG 4582 and AOP-48 procedures. The results showed that both the ATEC- and ATBC-modified propellants meet the stability requirements corresponding to at least ten years of storage at 25 °C. The modified propellants showed slightly lower heats of combustion. Both plasticizers were effectively integrated into the nitrocellulose matrix without compromising density or stability. This study confirms that citric-acid-based plasticizers are promising green alternatives to conventional phthalates, offering improved environmental compatibility while maintaining the required performance and safety of nitrocellulose propellants. Full article

Apple purée is a processed food typically obtained from ground apples, where quality depends on colour, consistency, and shelf-life. Thermal treatments are commonly applied to adjust rheology and deactivate enzymes responsible for post-packaging deterioration. This study evaluated the effects of heating temperature (87–102 °C) and duration (6–17 min) on the physical and chemical properties of Golden Delicious apple purée. Three independent batches were processed to examine intra-varietal variability. Chemical analyses assessed enzyme activity and nutritional profile, while physical tests focused on rheology. Image analysis was employed to characterise colour and syneresis. Results showed that short-duration heating at higher temperatures (>100 °C, <12 min) achieved desirable rheological properties but intensified browning. No significant correlations were found between residual enzymatic activity, polyphenol content, antioxidant activity, and thermal treatment conditions. This suggests that changes in colour and texture are primarily related to the physical parameters of heating independently of the origin batch. In contrast, the batch had a significant impact on enzymatic and nutritional profiles, highlighting the need for strict monitoring of incoming fruit. Overall, the heating conditions influenced the visual and textural quality of the purée, while the variability in raw materials remained a significant factor affecting its biochemical characteristics. Full article

A novel xylanase gene (RuXyn854) was identified from the rumen metagenome and was heterologously expressed in Escherichia coli to produce xylo-oligosaccharides (XOSs) as a prebiotic in this study. RuXyn854, a member of glycosyl hydrolase family 10, demonstrated peak enzymatic activity at pH 7.0 and 50 °C. RuXyn854 retains more than 50% of its activity after treatment at 100 °C for 10 min, highlighting the enzyme’s excellent heat resistance. RuXyn854 showed a preferential hydrolyzation of xylan, especially rice straw xylan. RuXyn854 activity was significantly increased in the presence of 15 mM Mn²⁺, 0.25% Tween-20, and 0.25% Triton X-100 (125%, 20%, and 26%, respectively). The reaction temperature (30, 40, and 50 °C), dosage (0.20, 0.27, and 0.34 U), and time (90, 120, and 150 min) of RuXyn854 affected the XOS yield and composition, with a higher yield at 0.27 U, 50 °C, and 120–150 min. Xylobiose, xylotriose, and xylotetraose were characterized as the predominant XOS products resulting from the enzymatic hydrolysis of wheat straw xylan by RuXyn854, with xylose present at a mere 0.49% of the total yield. The prebiotic potential of XOSs was assessed through in vitro fermentation with established probiotic strains of Bifidobacterium bifidum and Lactobacillus brevis. The results showed that, regardless of incubation time, XOSs stimulated the growth and xylanolytic enzyme secretion of the two probiotics compared to the controls. These results demonstrate that the feature of RuXyn854 to withstand temperatures up to 100 °C is impressive, and its ability to hydrolyze wheat xylan into XOSs promotes the growth of probiotics. Full article

Efficient development of karst geothermal resources relies on the accurate identification of thermophysical and hydrogeological parameters. In this paper, the integrated wellbore–reservoir model of fluid and heat transport is applied to identify hydrothermal parameters of the karst geothermal system in Tianjin, China, based on multi-type field test data. A natural state model is conducted by fitting steady-state borehole temperature measurement results to identify formation thermal conductivity, while reservoir permeability is determined via the Gauss–Marquardt–Levenberg optimization algorithm based on dynamic temperature and pressure data from pumping tests. The parameter identification results indicate a reservoir permeability of 5.25 × 10⁻¹⁴ m² and a corrected bottom-hole temperature of 109 °C. Subsequently, productivity optimization for actual heating demands (1.33 × 10⁵ m²) yields an optimal heat extraction efficiency of 6.17 MW, with a flow rate of 80 m³/h, an injection well perforated length of 388 m, and an injection temperature of 30 °C. Additionally, addressing reservoir heterogeneity, the study finds that high-permeability zones between wells significantly shorten the safe operation duration of geothermal doublets, and reducing flow rate can mitigate thermal breakthrough risk to a certain extent. Full article

The energy transition is an essential process for mitigating the effects of climate change in a global context where recent conflicts threaten energy security. Municipalities play an increasing role in achieving the decarbonization targets set at a national level, but they need effective tools to identify the most appropriate actions and policies for achieving quantitative targets. Among the tools available, energy models allow us to represent the evolution of the energy system under different boundary conditions or constraints and defining the least-cost pathways for sustainable development. The aim of this paper is to demonstrate the usefulness of a bottom-up modeling approach in the framework of the ETSAP TIMES model generator to represent and optimize the local-scale energy system of the city of Tito in Southern Italy, with a particular focus on the residential and tertiary sectors. The optimization of a Business-as-Usual reference scenario over a thirty-year time horizon (2020–2050) shows an initial situation based on the prevalent use of natural gas. The sensitivity analysis carried out by gradually increasing the cost of natural gas and providing subsidies for the purchase of heat pumps shows a 92% reduction in fossil fuel consumption and a 60% for CO₂ emissions as early as 2030. Full article

Climate change is a major constraint for common bean (Phaseolus vulgaris L.) cultivation in tropical regions, where elevated temperatures drastically affect reproductive efficiency and yield. This study aimed to evaluate the response of two local varieties, Matambú and Tayní, under passive induced heat using Open Top Chambers (OTC) in the humid tropics of Costa Rica. A factorial randomized block design with two genotypes and two environments (control and OTC) was applied to assess morphological, physiological, and yield-related traits. OTC increased daily maximum, minimum, and mean air temperatures by +2.29, +0.93, and +2.80 °C, respectively, and raised cumulative growing degree days by 325 °C·day⁻¹ compared with the control. Heat stress reduced grain yield by more than 80% (from 0.15 to 0.03 t·ha⁻¹) and significantly lowered the harvest index, confirming strong reproductive vulnerability. However, Matambú maintained higher nodulation and above-ground biomass under heat, whereas Tayní showed marked declines in pod set and nodule number. Correlation analyses revealed that pod number and harvest index were the strongest predictors of yield across environments. These results provide the first field evidence of local varietal responses to induced passive heat in Costa Rican common bean varieties and highlight Matambú as a valuable genetic resource for breeding climate resilient cultivars. Full article

Radial drilling technology, which involves drilling multiple micro-horizontal wellbores radially from a main wellbore, can effectively expand the contact area between the wellbore and the reservoir, as well as the swept volume of thermal fluid. It is a promising technology for enhancing the efficiency of heavy oil thermal recovery. However, a systematic numerical simulation study on the application of this technology in the cyclic steam stimulation (CSS) development of heavy oil reservoirs is currently lacking. This paper establishes a numerical thermal recovery model for heavy oil reservoirs based on an unstructured grid modeling method, which can accurately describe the complex geometry of multi-layer, multi-branch radial wells. The model is discretized using the finite volume method and solved with a fully implicit method. Then, based on the geological parameters of a typical heavy oil reservoir, a comparative study was conducted on the production dynamics and physical field evolution of horizontal wells, single-layer radial wells, and dual-layer radial wells during the CSS process. The results indicate that, compared to conventional well types, dual-layer multi-branch radial wells can simultaneously inject steam into the upper and lower parts of the reservoir. This forms a more balanced and extensive three-dimensional heated body, significantly improving the planar sweep efficiency of heat and the uniformity of reserve recovery, thereby substantially increasing crude oil production and recovery factor. Compared to the horizontal well scenario, using dual-layer radial wells for CSS can increase cumulative oil production by 44.8%. Full article