Search Results (85,900)

The rapid expansion of high-speed railway networks has increased the operational energy demand and indoor overheating risk of large-scale, high-volume railway station buildings. Natural ventilation is a climate-responsive passive strategy that can improve indoor environmental quality and reduce reliance on mechanical cooling. However, its contribution to the operational sustainability of large transportation buildings remains insufficiently quantified, particularly in hot-summer and cold-winter regions. This study investigates a seasonally adaptive window-opening strategy for Chengdu Station, with particular attention to major functional spaces such as waiting halls and commercial areas. A DesignBuilder model was used to simulate six ventilation scenarios, ranging from doors-only operation to fully open doors and windows. The effects of different window-opening ratios on hourly indoor temperature, relative humidity, adaptive thermal comfort, and annual building energy use were systematically evaluated. The simulation approach was further assessed against field measurements obtained from a comparable large railway station. The results reveal a pronounced nonlinear and seasonal response to the window-opening ratio. In winter, maintaining a very low opening ratio or keeping only the entrance doors open limits unnecessary heat loss. During the transitional seasons, opening ratios of 40–60% are sufficient to remove residual indoor heat while maintaining acceptable thermal conditions. In summer, the marginal improvement in ventilation performance becomes limited when the side-window opening ratio exceeds approximately 80%; therefore, an opening ratio of 80% was selected as a practical operating threshold rather than an absolute thermal optimum. Based on these seasonal characteristics, a month-by-month window-opening strategy was developed. Compared with the doors-only baseline, the proposed strategy reduced the annual high-temperature-hour ratio from 33.4% to 16.36%, corresponding to a decrease of 17.04 percentage points and a relative reduction of approximately 51.0%. Total annual building energy use decreased from 32,238.8 MWh to 25,923.8 MWh, representing an energy saving of 19.6%. These findings demonstrate that seasonally adaptive natural ventilation can simultaneously reduce overheating risk and operational energy demand while maintaining acceptable indoor thermal conditions. The proposed strategy provides a quantitative basis for the sustainable, energy-efficient, and intelligently managed operation of large-space railway stations in hot-summer and cold-winter regions. Full article

This study presents a comparative analysis of urban land-use sustainability in Barcelona and Izmir using a four-tier Decision Support Framework (DSF) supported by automated Google Earth Engine workflows. The framework integrates open satellite data, cloud-based spatial analysis, and policy-oriented indicators derived from Sentinel-2 and Landsat imagery. Outputs include LULC classification, NDVI, NDBI, a Sentinel-2-derived relative thermal proxy (sLST), the Composite Environmental Biophysical Index (CEBI), and distance-weighted urban expansion pressure. Classification accuracy reached 86.85% for Barcelona and 91.03% for Izmir. The cities exhibited distinct morphological and environmental profiles. Izmir had higher vegetation density than Barcelona (NDVI: 0.320 vs. 0.142), while harmonized Landsat summer LST values were similar in 2023, with Barcelona slightly warmer than Izmir (39.343 °C vs. 39.146 °C). Accordingly, sLST was used for relative intra-urban thermal assessment rather than absolute inter-city comparison. CEBI indicated higher environmental biophysical performance in Izmir (0.526) than Barcelona (0.446), interpreted strictly within the vegetation, thermal, and built-up components included in the index. Barcelona’s compact urban fabric exhibited stronger expansion pressure, whereas Izmir’s geographically constrained morphology indicated a more controlled growth dynamic. The findings demonstrate the value of transparent cloud-based spatial analytics for reproducible, evidence-based urban planning. Full article

The ultrafast photochemical reaction dynamics of a cyclic(alkyl)(amino)carbene–carbon disulfide (CAAC–CS₂) dimer containing two adjacent S–S bonds were investigated using femtosecond time-resolved infrared spectroscopy in combination with multireference electronic structure calculations. Time-resolved vibrational spectra and global kinetic analysis reveal that photoexcitation of the S–S n → σ* transition at 375 nm induces subpicosecond (<0.3 ps) homolytic cleavage of one S–S bond, generating a bis-thiyl diradical intermediate. This intermediate undergoes two competing pathways: recombination to regenerate the parent dimer with a time constant of 5.7–8.5 ps, or secondary cleavage of the remaining S–S bond to yield two CAAC–CS₂ monomers with a time constant of 30–35 ps. Wavelength- and temperature-dependent kinetic measurements demonstrate that the branching between these pathways is governed by excess excitation energy and thermally driven radical-pair fluctuations. Multireference electronic structure calculations support a sequential S–S bond cleavage mechanism, in good agreement with the experimental observations. These findings provide direct spectroscopic evidence for a bis-thiyl diradical intermediate and offer new mechanistic insight into the ultrafast photochemistry of adjacent S–S bonds. Full article

Mega-events present acute challenges in crowd safety, requiring sub-second monitoring, heterogeneous sensing, and strict privacy compliance at scale. We present SmartCrowd-IoT, a multi-modal crowd analytics framework built on a three-tier (sensor, edge, coordination) architecture incorporating (i) temporally aligned, reliability-aware weighted fusion across RGB, thermal, WiFi/BLE, acoustic, and RFID streams; and (ii) lightweight edge inference with federated differential privacy, enabling continuous model improvement without raw data leaving the venue. Evaluated on PETS2009, UCY, Mall, and a custom 61.3-h multi-modal corpus across three controlled mega-event simulations, SmartCrowd-IoT achieves 92.6% crowd-density accuracy, 77 ms end-to-end latency, 92.9% anomaly detection precision, and 83.4% backbone bandwidth reduction. Ablation studies confirm that both temporal alignment and reliability-aware fusion contribute significantly to these gains. The framework provides a deployable, privacy-by-design solution for mega-event crowd safety that scales to 200 edge nodes and 3000 sensors while maintaining sub-100 ms emergency response. Full article

This study numerically investigates the effects of manifold outlet width and lower-layer microchannel configuration on the thermohydraulic performance of a wedge-shaped manifold microchannel heat sink for high-heat-flux electronic cooling. A three-dimensional steady conjugate heat-transfer model was established in Ansys Fluent and assessed through grid-independence analysis and comparison with experimental pressure-drop and coolant-temperature-rise data. Simulations were conducted at inlet velocities of 1.0, 1.15, and 1.3 m/s to evaluate the average and maximum heat-source temperatures, temperature uniformity, pressure drop, thermal resistance, and performance evaluation criterion (PEC). Within the investigated manifold outlet-width range of 0.62–0.71 mm, increasing the outlet width produced concurrent reductions in the average and maximum heat-source temperatures and pressure drop, while improving the temperature uniformity of the heated surface. Among the outlet-width cases examined, 0.71 mm provided the most favorable thermohydraulic performance within the tested range. The influence of channel configuration depended on the evaluation objective. The wavy channel (WC) yielded the lowest heat-source temperatures and thermal resistance and therefore exhibited the best thermal performance among the investigated configurations. By contrast, the trapezoidal channel (TrC) maintained the highest PEC over the investigated inlet-velocity range and reached a maximum value of 1.140 at 1.3 m/s, indicating the most favorable balance between heat-transfer enhancement and hydraulic penalty. These results demonstrate that manifold outlet width and channel configuration should be selected jointly according to the required balance between temperature control and hydraulic performance. Full article

Approximately 2.3 billion people still cook over open fires or on basic stoves using polluting fuels, generating indoor air pollution responsible for 3.7 million premature deaths annually. Progress toward real-world health impact has been constrained by a persistent disconnect between computational fluid dynamics (CFD) modeling, standardized experimental evaluation, and sociocultural adoption research. This scoping review maps the current state of evidence across these three domains, analyzing 143 peer-reviewed studies published between 2007 and 2025 using predefined inclusion criteria and bibliometric analysis with VOSviewer v.1.6.20. Thirteen cookstove technologies were characterized by compiling heterogeneous evidence from Water Boiling Tests (WBTs), CFD simulations with k-ε turbulence closure, and CO and PM_2.5 emission protocols. Direct combustion stoves achieve thermal efficiencies of 10–21% under real-world conditions, while TLUD gasifiers and forced-draft systems with densified fuels reach 30–47%. Bibliometric analysis reveals that engineering, epidemiology, and social sciences operate as isolated research communities. None of the technology reviewed simultaneously integrated computational validation, field emissions assessment, and clinical impact evaluation; this a gap remains the central barrier to translating laboratory performance into measurable public health outcomes. These findings point toward integrated research designs connecting fluid dynamic optimization with exposure modeling, clinical follow-up, and the sociocultural needs of communities. Full article

Given the modernization of power systems in recent years, the quality of electrical energy is changing. With the increasing prevalence of harmonic components and rising current densities, conductor efficiency has become critically important. This study investigates the skin effect as a function of conductor geometry within the framework of electromagnetic field theory. Classical circular cross-section cable geometries and rectangular busbar systems were compared under an AC current of 1350 A (peak) across a frequency range of 50–500 Hz. The findings are comparatively presented, and their electromagnetic and thermal implications are discussed. Numerical modeling and simulation studies were performed using the Finite Element Method. COMSOL Multiphysics^® software AC/DC Module 6.2 version was used for the analyses. In the simulation studies, the magnetic flux density distribution within the conductor and the current concentration induced by eddy currents were analyzed. Frequency-dependent behavioral characteristics were examined in the analyses. The results revealed that the conductor with circular geometry exhibited a more severe skin effect. The rectangular conductor used in busbar systems was found to effectively distribute the current density across its surface area. Thus, rectangular geometry optimizes AC resistance. The analysis results revealed that conductor design and material selection depend not only on the cross-sectional area but also on the geometric shape factor. In this context, it was determined that conductor design has a decisive effect on electromagnetic power losses, which directly govern the heat generation potential within high-current systems. This study serves as a technical guide to evaluate frequency-dependent electromagnetic performance across a 50–500 Hz range—reflecting frequencies relevant to harmonic components—to assist in the design and optimization of high-current energy distribution systems. Full article

Background: This study investigates information-flow and logistics coordination challenges in Saudi Arabian construction projects within the context of ongoing national infrastructure developments, severe climatic conditions, and evolving labor regulations. Methods: Utilizing the Supply Chain Operations Reference (SCOR) framework, semi-structured interviews were conducted with 29 construction professionals spanning site-level engineers, logistics managers, project executives, and material suppliers over an extended 20-month monitoring period (March 2024–October 2025). Data were analyzed using thematic coding and mapped across the SCOR domains. Results: The findings reveal that logistics vulnerabilities stem predominantly from systemic information-sharing deficiencies, fragmented digital workflows, and weak stakeholder integration rather than standalone material constraints. Operational disruptions across Plan, Source, Make, Deliver, and Return are compounded by region-specific barriers including extreme thermal stress, migrant labor turnover, and high administrative fees for reverse logistics. Conclusions: To address these challenges, the study formulates a tiered, context-adjusted deployment framework for digital integration (BIM, IoT, and real-time tracking) tailored for both large infrastructure schemes and small-to-medium contractors. Staged implementation pathways and policy recommendations are provided to enhance supply chain resilience. Full article

Hybridizing concentrated solar power (CSP) with residual biomass allows supercritical CO₂ (sCO₂) power cycles to deliver dispatchable low-carbon electricity, but it is unclear whether the extra equipment of the more efficient layouts adds a life-cycle burden that offsets their thermodynamic gain. This work reports what is, to the authors’ knowledge, the first unified energy, exergy, environmental and exergoenvironmental comparison of two combined sCO₂–organic Rankine cycle (ORC) configurations—a simple and a recompression Brayton layout, both with reheating, regeneration and a toluene bottoming ORC—driven by a solar tower and a coconut-shell-biomass furnace. Life-cycle impacts are quantified with Eco-indicator 99, a damage-oriented method that scores construction, operation and decommissioning damage in milli-points (mPts), and are allocated to the exergy streams through the exergoenvironmental balance. Both cycles are modelled in Python with CoolProp properties and validated against published sCO₂ analyses (efficiency deviation below 7.3%). The recompression layout reaches 54.3% thermal and 32.0% second-law efficiency and cuts the exergy destruction from 173 to 128 kW. Its larger construction impact (22.6 vs. 20.1 mPts/h) is negligible against the shared biomass reheater (429.4 mPts/h), so it is also marginally cleaner overall (459 vs. 472 mPts/h). Efficiency-oriented layout selection is therefore environmentally safe, and the remaining leverage lies in the biomass supply chain. Full article

Gulf sturgeon are federally listed as “threatened” and are native to seven rivers along the northern Gulf of Mexico. Populations natal to the Pascagoula River have one verified spawning reach in the lower Bouie River, near Hattiesburg, MS. This reach is modified by four aggregate mining areas, referred to as pits. Researchers observed post-spawn Gulf sturgeon over-summering in pits rather than migrating to downstream holding areas in the Pascagoula River. We leverage acoustic telemetry and environmental data to assess drivers of arrival and departure from the Bouie River, describe vertical stratification in the water column in pits, and compare pit temperatures to those in holding areas. Generalized mixed linear modeling demonstrated that arrival was associated with lower discharge rates, whereas departure was associated with higher surface water temperatures and greater daily temperature extremes. Sturgeon had varying occupancy rates in pits, with four over-summering events over 3 years. Stratification formed in the pits in May and persisted through October, with bottom and middle strata exhibiting cooler temperatures than holding habitats. Cooler bottom temperatures indicate potential for thermal refuge in the pits. However, persistent stratification leads to low dissolved oxygen in bottom waters, warranting further research into the environmental stressors of this system. Full article

In this work, a comprehensive analysis of the relationship between photoluminescent, thermo-oxidative, and photocatalytic (upon simulated sunlight exposure) properties of ZnO powders is performed. The correlation between the X-ray diffraction and microscopic data is studied. ZnO powders of various sizes and morphologies were used: pseudo-spherical nanoparticles (30–50 nm), submicron faceted crystallites (100–500 nm), and plate- and rod-like microstructures (up to 20 μm). The mean specific surface area values were 32 m²/g, 3.8 m²/g, and 2.6 m²/g for pseudo-spherical nanoparticles, submicron faceted crystallites, and plate- and rod-like microstructures, respectively. According to the XRD data, microstresses and carbon-based impurities were present in ZnO nanoparticles, which is characteristic of nanomaterials synthesized at low temperatures. According to the photoluminescence spectroscopy data, the emission in ZnO was reduced due to high defectiveness, and characteristic emission bands indicated the presence of organic impurities. Upon long signal registration times, an intensive luminescence band with an effective maximum at 579 nm occurred, which indicated the presence of long-term components exhibiting decay times τ ~300 μs. According to the XRD data, the crystal structure parameters of ZnO submicro- and microparticles were close, with no impurities present. In their photoluminescence spectra, pronounced UV and defect-related bands were present with intensity ratios of 11.6 and 6.88, respectively. The decrease in the UV and defect-related luminescence band intensity ratios indicates deviation from the stoichiometry toward an increased Zn over oxygen content. At long signal registration times, in submicron ZnO particles, a luminescence band with maxima at 425 and 490 nm is present, which decays rapidly. An emission band in the 530 nm region is also present, which decays for ≤80 μs, and a weak long-wavelength emission decaying for ~100 μs. At long delay and strobe times (up to milliseconds), only an emission in the 460 nm region is observed, which we connect to the triplet–singlet transition of a defect center (F*, F⁺*). At lower intensities, an emission connected to the surface contamination by organic impurities is observed. In photoluminescence spectra of ZnO microparticles, no long-wavelength emission components are observed. However, upon immersing into methylene blue solution, a modification of the surface and UV region of the spectra is observed with signs of charge carrier recombination rate acceleration. It is shown that the catalytic action of ZnO powders in polyethylene thermo-oxidation processes is determined by a combination of factors. In addition to dispersity and concentration, which are the key parameters, the morphology of ZnO particles, the presence of impurities, the surface state, and the distribution of active sites have a significant influence on catalysis. It has been experimentally demonstrated that these secondary factors can markedly affect the rate of radical formation in polyethylene films and alter their resistance to oxidation. ZnO nanoparticles exhibited low catalytic activity in both photocatalysis (rate constant 0.146 min⁻¹) and thermocatalysis due to the high defect density of the crystallites and the presence of carbon-containing impurities. Submicron ZnO particles, owing to a high carrier generation rate and suppressed recombination (via trapping), demonstrated the highest photoactivity (rate constant 0.729 min⁻¹). Submicron ZnO particles exhibit a catalytic effect on the thermo-oxidation of polyethylene (PE films); however, at concentrations above 8 wt.% a transition to an inhibiting effect is observed. ZnO microparticles catalyzed the oxidation of PE films over a broader concentration range (1–12 wt.%), with oxidation inhibition observed only at 18 wt.%. At the same time, they demonstrated moderate photocatalytic activity (rate constant 0.256 min⁻¹). These characteristics of the samples correlate with data obtained by microscopy, photoluminescence spectroscopy, and X-ray diffraction analysis. Full article

Deep drilling equipment operates under high-load, strong-vibration, intermittent-impact, and variable environmental conditions, which motivate sensing systems that provide low-noise acquisition, synchronized triaxial measurements, local data integrity, and quantitative measurement-chain characterization. This paper presents a Zynq UltraScale+ MPSoC-based triaxial vibration sensing station for deep drilling equipment applications. The modular station integrates conditioned-voltage triaxial accelerometer interfaces, analog signal conditioning, 24-bit simultaneous analog-to-digital conversion, electrical isolation, local solid-state-drive storage, Ethernet/wireless communication, and GPS-disciplined oven-controlled crystal oscillator (OCXO) timing. The programmable logic performs deterministic acquisition, GPS pulse processing, oscillator calibration, and DMA transfer, while the processing system facilitates storage, network communication, device-state management, and host computer interaction. The sensing electronics are evaluated through zero-input noise, an experiment-specific input-amplitude-to-noise ratio, gain linearity, thermal stability, repeatability, and station-to-station local-PPS timing tests. The characterized electronics achieve a mean equivalent input noise of 0.31 microvolts, a test-derived ratio of 135.08 dB, and a mean station-to-station local-PPS falling-edge difference of 0.34 microseconds. A lightweight post-acquisition interpretation workflow using learnable multichannel weighted fusion, a convolutional autoencoder, a training-distribution-based quantile threshold, and an auxiliary classification branch achieves 0.9705 accuracy and 0.9704 F1-score on a public triaxial bearing dataset under the reported protocol. A crane-based experiment evaluates deployment feasibility and the sensing–analysis workflow using controlled operating events and a removable stationary mass disturbance. The results provide an engineering sensing basis for distributed monitoring studies on deep drilling equipment. Full article

A comprehensive analysis of the vertical thermodynamic structure during a compound dust–heatwave (dust–HW) event over the south-western Iberian Peninsula is presented in this study to investigate potential impacts on surface heat stress and cloud condensation nuclei (CCN) conditions. Lidar observations were performed at two dust-influenced stations, Évora (Portugal) and El Arenosillo/Huelva (Spain), during the intense June 2022 Saharan dust intrusion associated with a persistent HW event. The dust intrusion was characterized by high aerosol optical depths (up to ~1) and long duration (8 days). The dust layer extended from the surface up to approximately 6–7 km height, with the highest concentrations detected below 3–4 km. Similar temporal and vertical thermodynamic patterns were observed at both stations, indicating regional-scale consistency during the compound dust–HW event. Near-surface temperatures increased significantly during the dusty period compared with surrounding non-dusty days, suggesting enhanced surface heat-stress conditions under concurrent dust–HW environments. A distinct vertical thermodynamic structure was also identified, with air temperature (AT) increasing within the main dust layer, while relative humidity (RH) decreased below and increased above the layer where the highest dust concentrations were detected (3–4 km). Additional ERA5 vertical velocity diagnostics revealed ascending-motion signatures coinciding with RH-enhanced layers above the main dust intrusion, supporting dynamically consistent conditions for upward moisture transport during the event. Under these RH-enriched and ascending-motion conditions, retrieved CCN concentration estimates suggested potentially enhanced CCN activation environments above the main dust layer under moderate supersaturation scenarios. Overall, the results provide observational evidence consistent with a coupling among dust transport, thermodynamic variability, and CCN-related processes during HW conditions. These findings highlight the importance of understanding concurrent dust–HW environments in dust-influenced regions under projected future HW intensification associated with climate change, and their connection with aerosol-cloud interactions (ACI). Full article

With the aim of reducing and eventually eliminating CO₂ emissions, the aviation industry is investigating alternative fuels, with liquid hydrogen (LH2) being one of the most promising. Several research projects that deal with the subsystem design of liquid hydrogen aircraft have commenced, with specific attention given to the development of lightweight cryogenic tanks. Composite materials are potential candidates for cryogenic aviation applications, yet they experience issues with thermal stresses that result to various types of damage that should be thoroughly investigated, to enable reliable composite cryogenic structures. In this direction, the present work investigates the alternative finite element techniques for the thermo-mechanical analysis of the characteristic geometrical structural configuration. Thermo-mechanical stress analysis results derived from the investigated analysis methodologies are verified by their comparison to published results. The assessment of the alternative modeling techniques contributes to the adaptation of the FE modeling development strategy to the desired analysis type and the expected results and is directly applicable to the thermo-mechanical design of cryogenic components. The outcome of the investigation is demonstrated in the case of thermo-mechanical analysis of an outer tank of an LH2 storage system, performed with the optimal combination of shell and solid elements. Full article

This study obtained the energy levels and examined the partition function (Z) of a quantum system described by an Eckart-like potential model. By adopting the Greene–Aldrich approximation scheme for the centrifugal term, the radial Schrödinger equation (SE) is solved and the analytic expression of the energy eigenvalues is obtained. The ro-vibrational Z is computed by explicitly incorporating the rotational quantum number, a feature often neglected or misapplied in many studies. This result is used to evaluate the key thermodynamic properties (TP), including the Gibbs free energy (G), entropy (S), and enthalpy (H). Numerical analysis reveals that the Z increases monotonically with temperature, while the G decreases in accordance with statistical thermodynamics. The S exhibits saturation-like behaviour at higher temperatures, while the H displays convex growth with increasing thermal energy. Parametric studies demonstrate that the Eckart-like potential allows for the controlled tuning of TP, with variations in the potential parameters, including the screening parameter, having distinct effects. The results generalise existing models, reproduce the Hulthén potential under specific conditions, show the effect of the rotational quantum number of TP, and provide new insights into the ro-vibrational statistical mechanics of exponential-type potentials. Full article