Search Results (526)

A small induction furnace (SIF), which has the important components of copper coils, a ceramic jig, and a graphite crucible, employed for a glass souvenir production process, has been developed as a form of clean technology for multiphysics, consisting of electromagnetics analysis (EA) and thermal analysis (TA). First, two experiments were established to measure parameters for multiphysics results validation and boundary condition settings. Then, the parameters were applied to multiphysics, in which the EA revealed magnetic flux density (B) and ohmic losses, and the TA reported a temperature consistent with the experimental results, confirming the multiphysics credibility. Next, a ferrite flux concentrator was added to the SIF during development. Multiphysics revealed that PC40 ferrite, as a flux concentrator with a suitable design, could increase B by about 159% compared to the conventional SIF at the power of 1000 W. As expected, the B increases alongside the increase in power applied to the coils, and is more densely concentrated in the flux concentrator than in other regions, enhancing the production process efficacy. Lastly, the developed SIF was employed in the actual process and received good feedback from users. The novel research findings are the developed SIF and methodology, exclusively designed for this research and practically employed for a glass souvenir production process. Full article

While entrepreneurship continues to gain significance worldwide as a means for economic development and a tool for youth employment, coffee cultivation entrepreneurial intention becomes an essential goal to investigate and a necessary instrument. Accordingly, this research investigates the role of external factors, namely Access to Finance (ATF), Structural and Institutional Support (SIS), Physical Infrastructure Support (PIS), Social Influence (SIF) and Education and Training (ET), in stimulating Coffee Farming Entrepreneurial Intention (CFEI) among potential entrepreneurs (students). A sample of 318 participants from various universities in Saudi Arabia responded to an online questionnaire, forming the basis for analysis using Partial Least Squares-Structural Equation Modelling (PLS-SEM). The study reported different findings, such as a positive relationship between CFEI and other factors, namely PIS, SIF and ET. However, the study found no positive connection between ATF, SIS and CFEI. The study concluded by providing actionable recommendations for policymakers about stimulating coffee farming among students and contributing to the economic development process and youth employment. It also assists in the establishment of sustainable business environments for future generations. Full article

This review provides a summary of the existing literature on a crucial raw material for the production of isotopically pure semiconductors, which are essential for the development of second-generation quantum systems. Silicon-28-tetrafluoride (²⁸SiF₄) is used as an educt for several isotope-engineered chemicals, such as silane-28 (²⁸SiH₄) and silicon-28-trichloride (²⁸SiHCl₃), which are needed in the pursuit of various quantum technologies. We are exploring the entire chain from the synthesis of ²⁸SiF₄ to quantum applications. This includes the chemical properties of SiF₄, isotopic enrichment, conversion to silanes, conversion to bulk ²⁸Si and thin films, the physical properties of ²⁸Si (spin neutrality, thermal conductivity, optical properties), and the applications in quantum computing, photonics, and quantum sensing techniques. Full article

Speckles are inherent in structured laser-based light projection using diffractive optics such as metasurfaces or diffractive optical elements (DOEs). One application of structured light is to provide illumination for machine vision and depth sensing. This is particularly attractive for mobile or low-power applications, where metasurfaces provide a compact, customizable solution, which can furthermore reach extreme field of illuminations. However, the speckles might limit detection capabilities by, e.g., lowering the detection range or providing false results. In this work, we present a series of measurements with matching simulations on a 70 × 50 degrees diffractive diffuser using different light sources (varying divergence angles + VCSEL array) to quantify the impact of speckles. We observe a qualitative agreement in speckle correlation between the measurements and the simulations and explain, in part using cross-correlation for analysis, why we do not observe the same speckle pattern between the measurements and the simulations. By performing extra simulations, we conclude that by only changing the light source, there is a limit to the reduction of the speckle contrast which, we can achieve, and, to reduce it further, alternative approaches such as changing the design method of the diffractive diffuser must be harnessed. Full article

The fatigue of adhesive joints in offshore wind turbine blades is a critical and widespread challenge, necessitating an urgent focus on adhesive bond reliability. Given the constraints of full-scale testing, this research explores the fatigue endurance of carbon fiber–epoxy adhesive composites, integral to blade construction. Recognizing the fatigue characteristics’ sensitivity to environmental factors and joint dimensions, an innovative approach to fatigue modelling and evaluation is introduced. This method incorporates the influence of different environmental stresses and size effects. Specifically, a degradation coefficient and size impact factor (SIF) are introduced into the cyclic cohesive zone model, and a simulation-based analytic approach is proposed for analyzing adhesive fatigue. Furthermore, we introduce a reliability modelling procedure that integrates performance degradation theory to address the deteriorative characteristics inherent in adhesive fatigue. Subsequently, the specimens’ damage accumulation increased by 75% because of the stresses and escalated to 85% with adhesive joint size effects, causing carbon fiber Reinforced Polymer/epoxy adhesive joints to fail interfacially rather than in a mixed-mode manner. This study provides valuable insights for the safety analysis and assessment of adhesive joint performance in offshore wind turbine blades. Full article

A subway station’s operation is susceptible to accidents when there is a high-pressure gas pipeline overlaying it, and analyzing the correlations between the safety influencing factors (SIFs) in this operating situation can provide paths to reduce safety accidents. Thus, this paper investigated the coupling correlations between the SIFs. We firstly identified the SIFs during subway station operation under a high-pressure pipeline (SSOUHP) based on a literature review and discussion with experts. Then, the analytic hierarchy process (AHP) and coupling degree analysis (CDA) were combined to assess the coupling correlations between the SIFs, and Y subway station was selected to test the proposed hybrid coupling analysis approach. Research results show that (a) 23 second-level SIFs were identified and these SIFs can be summed up into five first-level SIFs, namely, human-related SIFs, pipeline-related SIFs, station-related SIFs, environment-related SIFs, and management-related SIFs; (b) the proposed hybrid approach can be used to evaluate the coupling correlations between SIFs; (c) of the coupling situations during Y subway station’s operation, the internal coupling correlations among environment-related SIFs, the coupling correlations between pipe-related SIFs and environment-related SIFs, and the coupling correlations among human-related SIFs, pipe-related SIFs, and environment-related SIFs are all greater than 1, and the coordination degree is 0.778, 0.781, and 0.783, respectively, which is a high security risk; (d) the overall coupling degree among all SIFs during Y subway station’s operation is 0.995 and the coordination degree is 0.809, which is a low safety risk. The research can enrich knowledge in the safety evaluation area, and provide a reference for onsite safety management. The results are basically consistent with the conclusion of the enterprise report, which verifies the scientificity and validity of the evaluation method. Full article

Solar-induced chlorophyll fluorescence (SIF) serves as a proxy indicator for vegetation photosynthesis and can directly reflect the growth status of vegetation. Using SIF for drought monitoring offers greater potential compared to traditional vegetation indices. This study aims to develop and validate a novel approach, the improved Temperature Fluorescence Dryness Index (iTFDI), for more accurate drought monitoring in Henan Province, China. However, the low spatial resolution, data dispersion, and short temporal sequence of SIF data hinder its direct application in drought studies. To overcome these challenges, this study constructs a random forest SIF downscaling model based on the TROPOspheric Monitoring Instrument SIF (TROPOSIF) and the Moderate-resolution Imaging Spectroradiometer (MODIS) data. Assuming an unchanging spatial scale relationship, an improved SIF (iSIF) product with a temporal resolution of 500 m over the period March to September, 2010–2022 was obtained for Henan Province. Subsequently, using the retrieved iSIF and the surface temperature difference data, the iTFDI was proposed, based on the assumption that under the same vegetation cover conditions, lower soil moisture and a greater diurnal temperature range of the surface indicate more severe drought. Results showed that: (1) The accuracy of the TROPOSIF downscaling model achieved coefficient of determination (R²), mean absolute error (MAE), and root mean square error (RMSE) values of 0.847, 0.073 mW m⁻² nm⁻¹ sr⁻¹, and 0.096 mW m⁻² nm⁻¹ sr⁻¹, respectively. (2) The 2022 iTFDI drought monitoring results indicated favorable soil moisture in Henan Province during March, April, July, and August, while extensive droughts occurred in May, June, and September, accounting for 70.27%, 71.49%, and 43.61%, respectively. The monitored results were consistent with the regional water conditions measured at ground stations. (3) The correlation between the Standardized Precipitation Evapotranspiration Index (SPEI) and iTFDI at five stations was significantly stronger than the correlation with the Temperature Vegetation Dryness Index (TVDI), with the values −0.631, −0.565, −0.612, −0.653, and −0.453, respectively. (4) The annual Sen’s slope and Mann–Kendall significance test revealed a significant decreasing trend in drought severity in the southern and western regions of Henan Province (6.74% of the total area), while the eastern region showed a significant increasing trend (4.69% of the total area). These results demonstrate that the iTFDI offers a significant advantage over traditional indices, providing a more accurate reflection of regional drought conditions. This enhances the ability to identify drought trends and supports the development of targeted drought management strategies. In conclusion, the iTFDI constructed using the downscaled iSIF data and surface temperature differential data shows great potential for drought monitoring. Full article

In order to study the effects of soybean isoflavones on the growth performance and lipid metabolism of juvenile Chinese mitten crabs, six experimental diets were formulated by gradient supplementation with 0%, 0.004% and 0.008% soybean isoflavones at different dietary lipid levels (10% and 15%). The groups were named as follows: NF-0 group (10% fat and 0% SIFs), NF-0.004 group (10% fat and 0.004% SIFs), NF-0.008 group (10% fat and 0.008% SIFs), HF-0 group (15% fat and 0% SIFs), HF-0.004 group (15% fat and 0.004% SIFs) and HF-0.008 group (15% fat and 0.008% SIFs). All crabs with an initial weight of 0.4 ± 0.03 g were fed for 8 weeks. The results showed that dietary supplementation with 0.004% or 0.008% SIFs significantly increased the weight gain and specific growth rate of crabs. Diets supplemented with 0.004% or 0.008% SIFs significantly reduced the content of non-esterified free fatty acids and triglycerides in the hepatopancreas of crabs at the 10% dietary lipid level. Dietary SIFs significantly decreased the relative mRNA expressions of elongase of very-long-chain fatty acids 6 (elovl6), triglyceride lipase (tgl), sterol regulatory element-binding protein 1 (srebp-1), carnitine palmitoyltransferase-1a (cpt-1a), fatty acid transporter protein 4 (fatp4), carnitine palmitoyltransferase-2 (cpt-2), Δ9 fatty acyl desaturase (Δ9 fad), carnitine palmitoyltransferase-1b (cpt-1b), fatty acid-binding protein 10 (fabp10) and microsomal triglyceride transfer protein (mttp) in the hepatopancreas of crabs. At the 15% dietary lipid level, 0.008% SIFs significantly increased the relative mRNA expressions of fatty acid-binding protein 3 (fabp3), carnitine acetyltransferase (caat), fatp4, fabp10, tgl, cpt-1a, cpt-1b and cpt-2 and significantly down-regulated the relative mRNA expressions of Δ9 fad and srebp-1. In conclusion, SIFs can improve the growth and utilization of a high-fat diet by inhibiting genes related to lipid synthesis and promoting lipid decomposition in juvenile Chinese mitten crabs. Full article

Inflammatory Bowel Disease (IBD) is a chronic condition that affects approximately 1.6 million Americans. While current polyphenols for treating IBD can be expensive and cause unwanted side effects, there is an opportunity regarding a new drug/polymer formulation using silymarin and an electrospray procedure. Silymarin is a naturally occurring polyphenolic flavonoid antioxidant that has shown promising results as a pharmacological agent due to its antioxidant and hepatoprotective characteristics. This study aims to produce a drug–polymer complex named the SILS100-Electrofiber complex, using an electrospray system. The vertical set-up of the electrospray system was optimized at a 1:10 of silymarin and Eudragit^® S100 polymer to enhance surface area and microfiber encapsulation. The SILS100-Electrofiber complex was evaluated using drug release kinetics via UV Spectrophotometry, Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Differential Scanning Calorimetry (DSC). Drug loading, apparent solubility, and antioxidant activity were also evaluated. The study was successful in creating fiber-like encapsulation of the silymarin drug with strand diameters ranging from 5–7 μm, with results showing greater silymarin release in Simulated Intestinal Fluid (SIF) compared to Simulated Gastric Fluid (SGF). Moving forward, this study aims to provide future insight into the formulation of drug–polymer complexes for IBD treatment and targeted drug release using electrospray and microencapsulation. Full article

Radar signal intra-pulse modulation recognition can be addressed with convolutional neural networks (CNNs) and time–frequency images (TFIs). However, current CNNs have high computational complexity and do not perform well in low-signal-to-noise ratio (SNR) scenarios. In this paper, we propose a lightweight CNN known as the cross-scale aware network (CSANet) to recognize intra-pulse modulation based on three types of TFIs. The cross-scale aware (CSA) module, designed as a residual and parallel architecture, comprises a depthwise dilated convolution group (DDConv Group), a cross-channel interaction (CCI) mechanism, and spatial information focus (SIF). DDConv Group produces multiple-scale features with a dynamic receptive field, CCI fuses the features and mitigates noise in multiple channels, and SIF is aware of the cross-scale details of TFI structures. Furthermore, we develop a novel time–frequency fusion (TFF) feature based on three types of TFIs by employing image preprocessing techniques, i.e., adaptive binarization, morphological processing, and feature fusion. Experiments demonstrate that CSANet achieves higher accuracy with our TFF compared to other TFIs. Meanwhile, CSANet outperforms cutting-edge networks across twelve radar signal datasets, providing an efficient solution for high-precision recognition in low-SNR scenarios. Full article

Flash drought (FD) has attracted much attention due to its severe stress on vegetation ecosystems. Yet to date, the impacts of FD on vegetation ecosystems in different regions have not been fully evaluated and explored, especially for ecologically fragile areas. In this study, we identified the FD events in the Loess Plateau from 2000 to 2023 based on the attenuation rate in soil moisture percentile over time. The evolution process of FD, the driving roles of meteorological conditions and the responses of different vegetation types to FD were explored by vegetation indicators such as solar-induced chlorophyll fluorescence (SIF), SIF_yield, SIF-RCI, etc. The results showed that FD events were predominantly concentrated in wetter areas with dense vegetation, with the highest frequency being 29. Meteorological factors contributed differently to the occurrence and development of FD. The responses of vegetation to FD were not only related to vegetation types (cropland was more sensitive to FD than forest and grassland) but were also significantly influenced by background climate. The SIF_yield anomaly of vegetation was more sensitive than SIF anomaly and SIF-RCI. The results advance our understanding of the formation mechanisms of FD and facilitate the exploration of vegetative photosynthetic responses to FD. Full article

Calculating the hydro-mechanical coupling stress-intensity factor (SIF) is an important basis for conducting safety evaluations in geotechnical engineering. The current methods used to calculate hydro-mechanical coupling multi-crack SIFs have difficulties concerning their complicated solution processes and unsuitable stress field expressions. In this paper, a new semi-analytical method is proposed based on a new hydro-mechanical coupling stress function and the extended reciprocal theorem of the work integral formula to calculate hydro-mechanical coupling multi-crack SIFs, which can be verified by comparison with the results available in the literature. The new semi-analytical method is applicable to an arbitrary number of cracks under arbitrary hydro-mechanical coupling loading and facilitates a more effective representation of the water pressure effect on the stress field. Moreover, the influence of the integral path and loading conditions is also discussed, and the results revealed an integral path radius of r₂ < 0.75 mm when the crack spacing b is 1.5 mm. When σ_y and P_h are constant at 15 MPa, the SIFs are almost the same for different σ_y/P_h, while the maximum circumferential stresses at r = 0.25 mm are 15.79 MPa, 20.83 MPa, and 25.78 MPa. Full article

In 2022, a severe drought and heatwave occurred in the middle and lower reaches of the Yangtze River Basin. Previous studies have highlighted the severity of this event, yet the relevance of soil moisture (SM), as well as vapor pressure deficit (VPD) and vegetation damage, remained unclear. Here, we utilized solar-induced chlorophyll fluorescence (SIF) and various flux data to monitor the impact of drought on vegetation and analyze the influence of different environmental factors. The results indicated a severe situation of drought and heatwave in the Yangtze River Basin in 2022 that significantly affected vegetation growth and the ecosystem carbon balance. SIF and NDVI have respective advantages in reflecting damage to vegetation under drought and heatwave conditions; SIF is more capable of capturing the weakening of vegetation photosynthesis, while NDVI can more rapidly indicate vegetation damage. Additionally, the correlation of SM and SIF are comparable to that of VPD and SIF. By contrast, the differentiation in the severity of vegetation damage among different types of vegetation is evident; cropland is more vulnerable compared to forest ecosystems and is more severely affected by drought and heatwave. These findings provided important insights for assessing the impact of compound drought and heatwave events on vegetation growth. Full article

Coupling solar-induced chlorophyll fluorescence (SIF) with gross primary productivity (GPP) for ecological function integration research presents numerous uncertainties, especially in ecologically fragile and climate-sensitive arid regions. Therefore, evaluating the suitability of SIF data for estimating GPP and the feasibility of improving its accuracy in the northern region of Xinjiang is of profound significance for revealing the spatial distribution patterns of GPP and the strong coupling relationship between GPP and SIF in arid regions, achieving the goal of “carbon neutrality” in arid regions. This study is based on multisource SIF satellite data and GPP observation data from sites in three typical ecosystems (cultivated and farmlands, pasture grasslands, and desert vegetation). Two precision improvement methods (canopy and linear) are used to couple multiple indicators to determine the suitability of multisource SIF data for GPP estimation and the operability of accuracy improvement methods in arid regions reveal the spatial characteristics of SIF (GPP). The results indicate the following. (1) The interannual variation of GPP shows an inverted “U” shape, with peaks values in June and July. The cultivated and farmland areas have the highest peak value among the sites (0.35 gC/m²/month). (2) The overall suitability ranking of multisource SIF satellite products for GPP estimation in arid regions is RTSIF > CSIF > SIF_OCO2_005 > GOSIF. RTSIF shows better suitability in the pasture grassland and cultivated and farmland areas (R² values of 0.85 and 0.84, respectively). (3) The canopy method is suitable for areas with a high leaf area proportion (R² improvement range: 0.05–0.06), while the linear method is applicable across different surface types (R² improvement range: 0.01–0.13). However, the improvement effect of the linear method is relatively weaker in areas with high vegetation cover. (4) Combining land use data, the overall improvement of SIF (GPP) is approximately 0.11%, and the peak values of its are mainly distributed in the northern and southern slopes of the Tianshan Mountains, while the low values are primarily found in the Gurbantunggut Desert. The annual mean value of SIF (GPP) is about 0.13 mW/m²/nm/sr. This paper elucidates the applicability of SIF for GPP estimation and the feasibility of improving its accuracy, laying the theoretical foundation for the spatiotemporal coupling study of GPP and SIF in an arid region, and providing practical evidence for achieving carbon neutrality goals. Full article

Solar-induced chlorophyll fluorescence (SIF) has been widely utilized to track the dynamics of gross primary productivity (GPP). It has been shown that the photochemical reflectance index (PRI), which may be utilized as an indicator of non-photochemical quenching (NPQ), improves SIF-based GPP estimation. However, the influence of weather conditions on GPP estimation using SIF and PRI has not been well explored. In this study, using an open-access dataset, we examined the impact of the clearness index (CI), which is associated with the proportional intensity of solar incident radiation and can represent weather conditions, on soybean GPP estimation using SIF and PRI. The midday PRI (xanthophyll de-epoxidation state) minus the early morning PRI (xanthophyll epoxidation state) yielded the corrected PRI (ΔPRI), which described the amplitude of xanthophyll pigment interconversion during the day. The observed canopy SIF at 760 nm (${\mathrm{S}\mathrm{I}\mathrm{F}}_{\mathrm{T}\mathrm{O}\mathrm{C}\_760}$) was downscaled to the broadband photosystem-level SIF for photosystem II (${\mathrm{S}\mathrm{I}\mathrm{F}}_{\mathrm{T}\mathrm{O}\mathrm{T}\_\mathrm{F}\mathrm{U}\mathrm{L}\mathrm{L}\_\mathrm{P}\mathrm{S}\mathrm{I}\mathrm{I}}$). Our results show that GPP can be accurately estimated using a multi-linear model with ${\mathrm{S}\mathrm{I}\mathrm{F}}_{\mathrm{T}\mathrm{O}\mathrm{T}\_\mathrm{F}\mathrm{U}\mathrm{L}\mathrm{L}\_\mathrm{P}\mathrm{S}\mathrm{I}\mathrm{I}}$ and ΔPRI. The ratio of GPP measured using the eddy covariance (EC) method (${\mathrm{G}\mathrm{P}\mathrm{P}}_{\mathrm{E}\mathrm{C}}$) to GPP estimated using ${\mathrm{S}\mathrm{I}\mathrm{F}}_{\mathrm{T}\mathrm{O}\mathrm{T}\_\mathrm{F}\mathrm{U}\mathrm{L}\mathrm{L}\_\mathrm{P}\mathrm{S}\mathrm{I}\mathrm{I}}$ and ΔPRI exhibited a non-linear correlation with the CI along both the half-hourly (R² = 0.21) and daily scales (R² = 0.25). The GPP estimates using ${\mathrm{S}\mathrm{I}\mathrm{F}}_{\mathrm{T}\mathrm{O}\mathrm{T}\_\mathrm{F}\mathrm{U}\mathrm{L}\mathrm{L}\_\mathrm{P}\mathrm{S}\mathrm{I}\mathrm{I}}$ and ΔPRI were significantly improved by the addition of the CI (for the half-hourly data, R² improved from 0.64 to 0.71 and the RMSE decreased from 8.28 to 7.42 $\mathsf{\mu }$mol•m⁻²•s⁻¹; for the daily data, R² improved from 0.71 to 0.81 and the RMSE decreased from 6.69 to 5.34 $\mathsf{\mu }$mol•m⁻²•s⁻¹). This was confirmed by the validation results. In addition, the GPP estimated using the Random Forest method was also largely improved by considering the influences of the CI. Therefore, our findings demonstrate that GPP can be well estimated using ${\mathrm{S}\mathrm{I}\mathrm{F}}_{\mathrm{T}\mathrm{O}\mathrm{T}\_\mathrm{F}\mathrm{U}\mathrm{L}\mathrm{L}\_\mathrm{P}\mathrm{S}\mathrm{I}\mathrm{I}}$ and ΔPRI, and it can be significantly enhanced by accounting for the CI. These results will be beneficial to vegetation GPP estimation using different remote sensing platforms, especially under various weather conditions. Full article