Search Results (5,058)

Ultra-high-performance concrete (UHPC) is widely used due to its strength, toughness, and durability. Shrinkage issues are the primary cause of concrete cracking and one of the main factors limiting the widespread application of UHPC in structural engineering. The shrinkage properties of UHPC vary depending on curing conditions. Research indicates that after thermal curing, the pore structure of UHPC is optimized, resulting in a significant reduction in shrinkage values. Based on the superposition principle, temperature creep coefficients and humidity creep coefficients are introduced to correct the temperature and humidity in the test environment to a constant temperature (20 °C) and humidity (75% relative humidity). The B3 coefficient of variation method was used to compare five different creep prediction models. The CEB-FIP2010 model was selected as the benchmark creep model, and curing condition coefficients were incorporated into the model to establish a comprehensive creep calculation model considering curing conditions. After 550 days of steam curing, the shrinkage strain of the UHPC specimens was approximately 28.9% of that of the uncured specimens. The additional creep deformation caused by temperature and humidity in the uncured and steam-cured specimens accounted for approximately 10% and 20% of the total creep deformation over 550 days, respectively. The strain development rates for both tensile and compressive strains in steam-cured specimens were lower than those in uncured specimens. A ten-year long-term creep simulation of UHPC precast joint beams was conducted using the finite element software Midas-Fea, and the comparison results validated the reliability of the comprehensive creep model. Full article

To elucidate the influence of water on terahertz (THz) spectral responses, terahertz time-domain spectroscopy (THz-TDS) was employed to monitor the thermal decomposition of copper(II) sulfate pentahydrate in this study. Continuous dehydration of the hydrate induces pronounced variations in the THz signal. At the initial stage of thermal decomposition, these changes primarily originate from the evolving state and amount of water confined within the CuSO₄·5H₂O lattice. After detaching from the crystalline framework, the released water molecules do not evaporate immediately; instead, they transiently reside near the copper sulfate as free water. When the temperature reaches approximately 60 °C, a dynamic equilibrium is established between crystalline water and free water. The THz spectral data reveal that the sample exhibits its strongest THz absorption at this temperature. Consequently, the THz signal during decomposition displays a characteristic trend: an initial decrease followed by an enhancement. These findings demonstrate that THz-TDS represents a promising approach for probing the state and content of water, thereby contributing to the development of a powerful analytical tool for fundamental studies in mineralogy. Full article

Fourier-transform spectroscopy is a widely used technique for determining the spectral and thermal properties of a target. However, target temperature variations during measurement can compromise the spectral accuracy. Temperature fluctuations induce oscillations superimposed on the target spectrum. These oscillations, referred to as scene-change artifacts, degrade the spectral accuracy. The literature is divided, with theoretical predictions suggesting negligible artifacts and growing experimental evidence reporting significant artifacts. This paper presents a theory and experimental validation of scene-change artifacts originating from target temperature variations. Traditionally, the interferogram offset is assumed to be constant, an invalid assumption for a changing scene. The error is subsequently Fourier-transformed, producing scene-change artifacts. Accurately estimating the truth spectrum is often challenging. To address this, we propose the signal-to-scene-change-artifact ratio, a metric that quantifies the impact of scene-change artifacts without knowledge of the truth spectrum. The artifacts will be eliminated by estimating the interferogram offset using smooth offset correction. Furthermore, the interferogram offset enables determination of the target’s temperature with a greater accuracy and an increased temporal resolution compared to using the spectra. These results will demonstrate that a smooth offset correction can improve the spectrum and temperature accuracy on thermally variant targets when measured with a Fourier-transform spectrometer. Full article

Recent advances in machine design, automation, and industrial digitalization have transformed Coordinate Measuring Machines (CMMs) from standalone inspection devices into fully integrated elements of automated manufacturing systems. In the automotive sector, CMMs increasingly operate in workshop, near-line, and in-line environments, interacting with production equipment and contributing directly to process control and zero-defect manufacturing strategies. This paper presents a structured methodology for the industrial deployment of automated CMMs in automotive mechanical manufacturing. The proposed approach is illustrated through an industrial use case involving the dimensional inspection of mechanically machined components under real production conditions. The methodology addresses machine design selection, sensor configuration, environmental constraints, and multi-axis architectures, as well as validation and acceptance procedures based on the ISO 10360 series. Particular attention is given to the integration of CMMs within automated manufacturing systems, including robustness against thermal variations, vibrations, and contamination, and the use of metrological data for feedback to machining processes. Rather than introducing new metrological principles, the proposed approach focuses on the structured integration of established engineering practices into a coherent lifecycle-based deployment framework. Based on industrial experience, the proposed methodology is illustrated through an industrial case study to support the reliable of automated dimensional inspection, reduce measurement-related risks, and support the integration of CMMs as active components of modern automated manufacturing systems. Full article

The Qinghai–Tibet Plateau is characterized by highly complex terrain, and civil aviation serves as a primary mode of transportation for regional mobility. A comprehensive understanding of wind field characteristics within the terminal areas of plateau mountain airports, as well as the formation mechanisms of wind shear during different flight phases, is of considerable importance for flight risk assessment, improvement of transport efficiency, and refined meteorological support services. However, studies focusing on wind field structures within the terminal areas of plateau mountain airports remain limited. In this study, dry-season observations from Coherent Doppler Wind Lidars at two critical locations in the terminal area of Lhasa Airport are analyzed. A comparative analysis is conducted on the vertical structure, diurnal variation, and the characteristics of turbulence and wind shear under different terrain conditions. The results show that above the valley height, both sites are dominated by stable westerly winds. Below the valley height, the wind field is strongly influenced by terrain complexity. At the Lhasa Airport site (LS), the valley is regular in shape and has a stable orientation. The prevailing wind direction is aligned with the valley, and easterly winds dominate the entire valley, especially in the middle and lower layers. In contrast, the Qushui site (QS) is located at the confluence of two valleys, where the terrain is more open and complex. The prevailing wind shifts clockwise with height, from northeasterly in the lower layers to easterly aloft. The wind direction is less concentrated than at LS. In terms of diurnal variation, a stable easterly layer forms within the valley at LS in the morning. A transition layer of about 200–300 m exists between this layer and the westerlies aloft. Within the transition layer, wind speed is relatively weak and wind direction stability is low. At QS, morning winds are weaker and more variable within the valley. Wind direction stability increases with height. In the afternoon, both sites are influenced by the downward transport of westerly momentum. However, the effect is more pronounced at QS, where low-level wind speed is higher and wind direction is more stable. Turbulence at both sites peaks between 14:00 and 17:00 and is mainly driven by thermally induced updrafts. Turbulence intensity at QS is stronger, with a vertical extent exceeding 1500 m, indicating a stronger response to thermal forcing. Wind shear at both sites mainly occurs between 12:00 and 18:00, with peak frequency from 13:00 to 17:00. This period is consistent with peak turbulence activity. Wind shear at LS occurs more frequently and lasts longer. At QS, momentum transport from above 1500 m enhances wind shear occurrence at 800–1000 m. The causes of wind shear differ under different prevailing wind conditions. Under prevailing westerlies, wind shear is mainly caused by rapid changes in wind direction with height. Under prevailing easterlies, it is primarily associated with an enhanced vertical gradient of wind speed. These results reveal the significant influence of complex terrain on low-level wind structures and causes of wind shear. The findings provide a scientific basis for operational decision-making at plateau mountain airports. Full article

Green husks, which are the fleshy pericarp of Juglans regia L. fruit, are an abundant yet under-utilized source of bioactive compounds. They are useful for plant defense and have potential for valorization to multiple commercial products. This study characterized total phenolic content (TPC) and individual phenolics in green husks of four Hungarian-bred cultivars (Milotai 10, Milotai intenzív, Milotai kései, Esterhazy kései) and one U.S. cultivar (Chandler). Phenolic compounds were extracted with aqueous organic solvents, quantified by HPLC-DAD and qualitatively identified by HPLC-MS. Linear mixed-effects models were used to assess the effects of cultivar, year, sampling time, and cumulative growing degree days (GDDs) on TPC and compound profiles. Mean TPC ranged from 34.9 to 57.2 mg GAE g⁻¹ DW, with significantly higher values in the warmest year, 2024, and in cultivar Esterhazy kései compared with Chandler. Across cultivars and years, phenolic levels were generally elevated at early lignification (S1, BBCH 73–75) and at full maturity (S5–S6, BBCH 87–88), with depressed concentrations during mid-fruit development (S2–S4, BBCH 77–86). Several hydroxycinnamic acids, flavonoids, and naphthoquinones showed cultivar-specific and year-dependent patterns. Thermal conditions (cumulative GDDs) explained a substantial proportion of residual variation in TPC. These results highlight the combined roles of genotype, seasonal climate, and developmental stage dependencies in biosynthetic processes of phenolics in walnut green husks despite the diversity in factor effects. Full article

Non-invasive temperature estimation during online operation is a critical challenge in enclosed micro-reaction systems, particularly when the thermal mass of the working fluid varies dynamically or is uncertain. Conventional model-based approaches typically rely on fixed thermal parameters, leading to significant estimation errors when the actual reagent volume deviates from nominal conditions. To address this limitation, this study proposes a volume-adaptive temperature estimation framework applied to an ultrafast quantitative polymerase chain reaction (qPCR) system. By modeling the heat-transfer pathways via a simplified resistance–capacitance (RC) network, a nonlinear least squares (NLS) algorithm within an output-error (OE) framework is employed to identify key thermal parameters online. The framework separates the estimation into an offline calibration stage—where a thermocouple-equipped chip provides ground-truth data—and an online deployment stage that relies solely on non-invasive external measurements. This approach allows the system to explicitly compensate for volume-induced variations in thermal inertia. Validation experiments on an ultrafast qPCR platform with reagent volumes ranging from 100 to 250 $\mathsf{\mu }\mathrm{L}$ and heating rates exceeding 20 °C/s demonstrate that the method achieves robust performance, maintaining a mean absolute error (MAE) of reagent temperature at 0.24 ℃ and restricting the average volume estimation error to within 1.37 $\mathsf{\mu }\mathrm{L}$. DNA gel electrophoresis results further confirm the biological reliability of the temperature prediction strategy by verifying amplification specificity. This work provides a generalised solution for precise thermal management in micro-systems subject to variable thermal loads. Full article

The present work examines methods for enhancing dimensional accuracy and circularity in CNC circular end milling processes. While conventional optimization often focuses solely on mechanical cutting parameters, this research integrates the Taguchi method, Response Surface Methodology (RSM), and Analysis of Variance (ANOVA) to explicitly quantify the impact of thermal equilibrium alongside cutting mechanics. The results reveal a novel finding: warm-up time is the dominant factor, contributing 41.01% to dimensional accuracy and 49.97% to circularity variation, significantly outweighing spindle speed and feed rate. The optimized parameter combination—comprising a specific warm-up protocol, depth of cut, and feed per tooth—improved dimensional accuracy by approximately 38% and circularity by 33%. This study provides a critical operational guideline for precision manufacturing: implementing a thermal stability protocol is a prerequisite for realizing the benefits of mechanical parameter optimization. Full article

To investigate the influence of external ambient temperature on the transmission characteristics of laser propagation in an internal channel, a simulation model of laser transmission within a closed channel is established in this study. The model comprehensively considers factors including gas density, refractive index distribution, and thermal deformation of optical components. Based on optical transmission theory, the model is used to calculate the beam drift characteristics and the variation in the Strehl ratio at different temperatures. The results indicate that ambient temperature has a significant impact on beam stability and quality. At low temperature (−30 °C), speckle structures appear in the laser spot, with minor drift along the X direction but obvious negative drift along the Y direction, mainly caused by the sinking of cold air driven by gravity and the refractive index gradient. The beam drift decreases initially with increasing temperature, reaches its minimum at around 10 °C, and then increases gradually as the temperature continues to rise. The Strehl ratio initially increases during the early stage of temperature rise, but diminishes in the high-temperature range due to intensified gas disturbances, enhanced thermal lensing effects, and aggravated mirror surface deformation. Full article

Investigation of deposystems, sediment routing, and basin architecture during Gondwana breakup refines understanding of Permian–Cretaceous landscape evolution in the central Andes. New chronostratigraphic and provenance constraints from the Eastern Cordillera and Subandean Zone of Bolivia (19–22°S) are based on U-Pb geochronology of detrital and volcanic zircons and ⁴⁰Ar/³⁹Ar dating of interbedded basalts. A discontinuous <2 km-thick Permian–Cretaceous succession records deposition in fluvial, lacustrine, alluvial fan, eolian, and shallow marine environments. Stratigraphic correlations indicate alternations between isolated half-graben subbasins and regional, non-compartmentalized basins. Detrital zircon age spectra from 18 sandstones document sediment recycling from western orogenic and magmatic arc sources and eastern cratonic basement. Synextensional successions of Early Triassic, Early Jurassic, and mid-Cretaceous age were sourced mainly from the west, including Carboniferous and Devonian rocks, while post-extensional fluvial and eolian systems were derived chiefly from the eastern craton. Variations in thickness, facies, and mafic magmatism reflect alternating extensional and neutral tectonic regimes, with localized synextensional subsidence potentially linked to extensional collapse, mantle plume activity, and South Atlantic opening. Comparison with Andean regions in Peru and Argentina indicates that episodic extension and post-extensional thermal subsidence accompanied subduction along the western margin of South America during Gondwana-Pangea breakup. Full article

This paper presents a comparative evaluation of a wave union (WU) time-to-digital converter (TDC) implemented on two Microchip flash-based field-programmable gate arrays (FPGAs): the radiation-tolerant RTG4 (RT4G150-1CG) and the low-power SmartFusion2 (M2S150TS-1FCG1152). Both implementations use an identical VHDL architecture consisting of parallel tapped delay lines (TDLs) each with a WU pattern generator, edge-coded logic encoding, and real-time statistical bin width calibration. Single-shot precision (SSP), defined as the standard deviation of consecutive period measurements derived from calibrated timestamps, is evaluated across four independent input channels. Measurements are performed at five input frequencies (1, 2, 10, 20, and 40 MHz) and six ambient temperatures ranging from 20 °C to 60 °C. At a low input frequency, the RTG4 implementation achieves a mean SSP of 6.97 ps, while IGLOO2 yields 10.12 ps under identical conditions. As the input frequency increases, the SSP of both platforms decreases and converges to approximately 4.5 ps. However, at elevated temperatures, both devices experience observable degradation in SSP. To quantify thermal robustness, a thermal sensitivity coefficient (TSC) is introduced, defined as the rate of SSP variation with temperature. The results show that the same WU TDC core implemented on a space-graded FPGA exhibits improved thermal stability and reduced channel-to-channel variance compared to its equivalent on a commercial platform. Full article

Additive manufacturing (AM) represents a quite interesting technology for manufacturing components of nuclear reactors. This work investigated the microstructural stability of 316 L steel fabricated via Laser Powder Bed Fusion (L-PBF) from room temperature to 650 °C. Despite the reduced susceptibility of the material to sensitization owing to its low carbon content, temperature variations may induce deleterious effects in nuclear safety-critical components. In as-printed condition, the microstructure is not stable and undergoes significant changes induced by thermal cycling up to 650 °C in Mechanical Spectroscopy (MS) tests: the typical melt-pool pattern disappears, a population of equiaxed grains substitutes the original ones elongated in the build direction, the average size of the cells forming a finer sub-structure inside the grains increases, texture changes, and the excess of vacancies induced by the rapid cooling is recovered. Although the current literature reports that the microstructure is stable up to 500 °C, MS results indicate that the aforesaid irreversible phenomena start at a lower temperature (~230 °C). The present results suggest that the microstructure of the printed material must be stabilized through suitable heat treatments before its application in structural components for nuclear reactors. Full article

This study investigates the heterogeneity of pore structures in lacustrine shale gas reservoirs, with a specific focus on shales from the Lower Cretaceous Shahezi Formation in the Lishu Fault Sag of the Songliao Basin. By integrating multi-scale characterization techniques—including high-pressure mercury intrusion, N₂/CO₂ adsorption, and nuclear magnetic resonance (NMR)—we examined the pore networks across five identified lithofacies: organic-rich clayey shale, organic-rich mixed shale, organic-rich siliceous shale, organic clayey shale, and organic mixed shale. The results indicate that mesopores (2–50 nm) constitute the dominant fraction of pore volume (31.7%–56.6%), followed by micropores (<2 nm) and macropores (>10 μm). Notable lithofacies-dependent variations were observed: organic-rich clayey shale exhibits abundant organic pores, clay interlayer pores, and intragranular dissolution pores with favorable connectivity; organic-rich siliceous shale is mainly dominated by inorganic pores with limited organic porosity; mixed shales are characterized by clay mineral contraction fractures and intergranular pores. The key controlling factors are mineral composition and organic matter abundance: clay content shows a positive correlation with pore volume and surface area in organic-rich clayey shale, but a negative correlation in organic mixed shale. Brittle minerals (quartz and feldspar) generally reduce porosity through compaction. Total organic carbon (TOC) displays a weak positive correlation with mesopore volume, while thermal maturity (Ro = 1.2%–1.73%) exerts influences that vary by lithofacies. In contrast to marine shales—which are dominated by high-maturity (Ro > 2.0%) organic pores and quartz-supported frameworks—terrestrial shales primarily rely on inorganic pores derived from clay minerals (e.g., illite). This study clarifies the relationships among lithofacies, pore structure, and controlling factors, thereby providing a basis for evaluating the gas potential of terrestrial shales. Full article

Insect populations are increasingly exposed to concurrent climate warming and agrochemical contamination, yet how these stressors interact to influence reproductive performance remains poorly understood. Because fertility can constrain population growth before survival declines, understanding how environmental stress affects reproduction is essential for predicting demographic responses. Here, we investigated how elevated temperatures and sublethal imidacloprid exposure during development and early-life interact with the insecticide resistance locus Cyp6g1 to influence male reproductive performance in Drosophila melanogaster. Males were reared from embryo to adulthood under factorial combinations of temperature and insecticide exposure, and mating behaviour and fertilisation success were subsequently quantified under benign assay conditions. Early-life heat reduced fertilisation success in a genotype-dependent manner, with a pronounced collapse observed in insecticide-susceptible males. Sublethal insecticide exposure modified this thermal response, restoring fertilisation success in susceptible males and producing non-additive interactions between thermal and agrochemical stress. In contrast, although mating frequency varied across treatments, it did not show the pronounced decline observed in fertilisation success, indicating that behavioural engagement does not necessarily predict functional reproductive output. These results suggest that environmental stress experienced during early-life can reshape reproductive performance, potentially through genotype-dependent shifts in physiological investment. Considering developmental stress history and genetic variation will therefore be important for predicting insect population responses to climate warming and environmental contamination. Full article

Agricultural ecosystems in northeastern Bangladesh are increasingly vulnerable to climate-induced stressors, particularly rising temperatures and seasonal droughts. While previous research has examined the climate’s impact on agriculture in broader contexts, no study has specifically investigated long-term seasonal vegetation and thermal dynamics in Sylhet. This study addresses this gap by assessing spatio-temporal variations in vegetation health under climate stress in the Sylhet region from 2005 to 2025 using remote sensing techniques. To investigate this problem, the study derived the Normalized Difference Vegetation Index (NDVI) and land surface temperature (LST) from Landsat satellite imagery and evaluated their seasonal behavior across the major cropping periods Rabi, Kharif I, and Kharif II. The relationship between vegetation health and surface temperature was examined using Pearson’s correlation matrix along with a statistical comparison to identify change patterns, transitions among vegetation and thermal stress classes, and the seasonal intensity of climate stress. The findings indicate that increased LST generally corresponds with reduced vegetation cover in lowland agricultural zones, whereas elevated areas with forest or tree covers show an opposite response. Distinct spatial hotspots of thermal stress and drought-prone zones were also identified, particularly during the dry Rabi season. These results highlight the idea that rising LST corresponds with declining NDVI values, indicating that increasing thermal stress and potential reductions in agricultural vegetation productivity and climate stress across Sylhet’s agricultural landscape have intensified markedly from 2005 to 2025, with clear seasonal differences in vulnerability. NDVI analysis reveals a consistent decline in vegetation health, while LST patterns show widespread transitions from moderate to high and severe thermal stress, particularly during the Kharif seasons. The observed NDVI decline under elevated LST conditions indicates reduced vegetation vigor and potential productivity within agricultural lands, rather than a direct reduction in cultivated areas, since NDVI primarily captures vegetation density and physiological condition. The strongest NDVI–LST inverse relationship occurs in Rabi and Kharif I, indicating vegetation’s cooling role, whereas this linkage weakens in Kharif II due to dominant monsoon-driven atmospheric controls. Full article