Search Results (1,213)

Metal powder compaction in rigid dies often suffers from high ejection forces, non-uniform density, and accelerated tool wear. We investigate an elastic-sleeve die concept in which a conical shrink-fit sleeve provides controllable radial confinement during pressing and elastic relaxation during extraction. An extensive experimental program on Fe-based and 316L powders, carried out in parallel with finite element analyses (SolidWorks Simulation version 2021; Marc Mentat 2005), quantified the roles of taper angle (α = 1–4°), axial pretension (Δh = 0.5–1.5 mm), and friction. Contact pressure increased from ≈52 MPa at α = 1° to ≈200 MPa at α = 3°, with negligible gains beyond 3°. For 316L, relative density reached ρ ≈ 0.889 at 325 kN with Δh = 1.5 mm; Fe–Cu–C achieved ρ ≈ 0.865 under identical conditions. The experimental results provided direct validation of the FEM, with calibrated viscoplastic simulations reproducing density–force trends within ≈±5% (mean density error ≈ 4.6%), while mid-stroke force differences (≈15–20%) reflected rearrangement/friction effects not captured by the constitutive law. The combined evidence identifies an optimal window of α ≈ 3° and Δh ≈ 1.0–1.5 mm that maximizes contact pressure and densification without overstressing the sleeve. Elastic relaxation of the sleeve facilitates extraction and suggests reduced ejection effort compared with rigid dies. These findings support elastic dies as a practical route to improved densification and tool life in powder metallurgy. Full article

The production of high-quality cassava planting material is a key strategy for mitigating the spread of pests and diseases. To promote the adoption of such strategies by farmers, it is essential to strengthen local capacities through knowledge transfer and the incorporation of innovative technologies, such as tunnels for rapid propagation (TxRPs), which have been successfully implemented in various international contexts. This study appraised the performance of four industrial cassava (Manihot esculenta Crantz) varieties—Corpoica Tai, Corpoica Belloti, Corpoica Ropain, and Corpoica Sinuana—under tunnel conditions at two locations on the Caribbean coast of Colombia. Planting material consisted of mini-cuttings (7–9 months old) with three buds. Five successive harvest cycles were assessed by measuring key growth parameters, including plant height, leaf number, SPAD (Soil Plant Analysis Development) chlorophyll index, leaf area, and biomass (dry weight and nutrient content). Environmental conditions within the tunnels, such as temperature and humidity, were regulated to promote rapid sprouting and accelerated growth of the cuttings. However, sprouting, vigor, and overall growth performance varied by variety. All four cassava varieties produced high-quality cuttings (>20 mm in diameter and >6 leaves), suitable for further seedling propagation. Cutting vigor increased across cycles, with productivity rising from over 60 cuttings/m² in the first cycle to more than 180 cuttings/m² by the fifth. Substrate mixtures enhanced both physical and chemical soil properties, depending on the source (CRT or CBL). The addition of coco peat or sand effectively minimized environmental impacts by preventing substrate compaction. The findings demonstrate the potential of tunnel-based systems to accelerate the production of high-quality cassava planting material, supporting improved productivity and sustainability in cassava cultivation for both farmers and industry stakeholders. Full article

This paper presents the design and implementation of an ultra-wideband MIMO antenna for sub-6 GHz 5G metal-frame smartphones. The proposed antenna array includes four pairs, each comprising a slotted patch element and an open-slot structure on the metallic rim. The design achieves compactness by sharing the same aperture, critical for overcoming metal-frame smartphone constraints. It minimizes the required ground clearance to 40 × 0.7 mm² to fit the limited space of metallic bezels while maintaining high inter-element isolation. Specifically, one element operates at 2.5–3.8 GHz and 4.8–7.0 GHz, while the other provides continuous coverage from 2.5 to 6.5 GHz, supporting all global sub-6 GHz 5G frequency bands. Specifically, one element operates at 2.5–3.8 GHz and 4.8–7.0 GHz, while the other offers continuous coverage from 2.5 to 6.5 GHz, supporting all sub-6 GHz 5G frequency bands. The open-slot configuration enlarges the operational bandwidth and improves isolation, achieving more than 12.6 dB isolation between elements. A prototype was fabricated and experimentally tested. Measured results indicate that the antenna array maintains a total efficiency above 56% and an envelope correlation coefficient below 0.18 across the target bands. The measured and simulated results are in good agreement, confirming the effectiveness of the proposed design. The proposed antenna is a strong candidate for next-generation 5G smartphone applications due to its wideband performance, high isolation, and compact integration. Full article

Overburden isolated grouting injection is an efficient and green mining technology. During the filling process, fly ash or gangue powder is mainly used as grouting material, and compaction grouting is carried out in the main stratum under the key stratum, thus realizing the control of surface subsidence and the protection of buildings (structures). In the process of grouting filling, slurry with high water-cement ratio (1:1) is needed to ensure its injectability and certain flow radius, which leads to large water demand and limited application in water-deficient mining areas. In addition, special geological structures such as faults have potential risks of slurry flowing into the working face. On the premise of not affecting the grout injectability, how to reduce the total water consumption of grout is one of the difficult problems to be solved urgently in the overburden isolated grouting injection. The experimental study on the feasibility of ultrasonic water reduction of grouting slurry is carried out in this paper, and the influence of ultrasonic cavitation on the fluidity of slurry is studied through experiments. The results show that ultrasonic waves can effectively improve the fluidity of slurry. Under the same fluidity, the water used for slurry preparation is reduced by 20% to 26%, and when the slurry with water-cement ratio of 0.8:1 is modified, its fluidity is equivalent to that of the slurry with a water-cement ratio of 1:1 in conventional engineering applications. The action time and power of the ultrasonic waves are the key factors affecting the modification effect of the slurry, and the ultrasonic power has a more significant influence on the action effect. The proposed ultrasonic cavitation water reduction modification method can effectively reduce the water used for slurry preparation, improve the efficiency, reliability and economic benefits of grouting filling, and provide important support for the application of the grouting filling method in restricted mining areas such as water-deficient mining areas. Full article

The dynamic development of agent systems and large language models opens up new possibilities for automating spatial and investment analyses. The study evaluated a reactive AI agent with an NLP interface, integrating Apache Spark for large-scale data processing with PostGIS as a reference point. The analyses were carried out for two areas: Nowy Sącz (36,000 plots, 7 layers) and Ostrołęka (220,000 plots). For medium-sized datasets, both technologies produced similar results, but with large datasets, PostGIS exceeded time limits and was prone to failures. Spark maintained stable performance, analyzing 220,000 plots in approximately 240 s, confirming its suitability for interactive applications. In addition, clustering and spatial search algorithms were compared. The basic DFS required 530 s, while the improved one reduced the time almost tenfold to 54–62 s. The improved K-Means improved the spatial compactness of clusters (0.61–0.76 vs. <0.50 in most base cases) with a time of 56–64 s. Agglomerative clustering, although accurate, was too slow (3000–6000 s). The results show that the combination of Spark, improved algorithms, and agent systems with NLP significantly speeds up the selection of plots for renewable energy sources, supporting sustainable investment decisions. Full article

Fractured tight sandstone reservoirs pose challenges for gas development due to low matrix porosity and permeability, complex pore structures, and pervasive fractures. This study focuses on the Bashijiqike Formation in the Keshen Gas Field, Kuqa Depression, aiming to clarify the geological controls on reservoir quality. Lithofacies, diagenetic facies, and fracture facies were systematically classified by core analyses, thin sections, scanning electron microscopy (SEM), cathodoluminescence (CL), X-ray diffraction (XRD), grain size analyses, mercury intrusion capillary pressure (MICP), well logs and resistivity imaging logging (FMI). Their impacts on porosity, permeability and gas productivity were quantitatively assessed. A ternary reservoir quality assessment model was established by coupling these three factors. Results show that five lithofacies, four diagenetic facies, and four fracture facies jointly control reservoir performance. The high-energy gravelly sandstone facies exhibit an average porosity of 6.0% and average permeability of 0.066 mD, while the fine-grained sandstone shows poor properties due to compaction and clay content. Unstable component dissolution facies enhance secondary porosity to 6.0% and permeability to 0.093 mD. Reticulate and conjugate fracture patterns correspond to gas production rates two to five times higher than those with single fractures. These findings support targeted reservoir classification and improved development strategies for ultra-deep tight gas reservoirs. Full article

The growing interest in smart buildings and the integration of IoT-based technologies is driving the development of new tools for monitoring and optimizing indoor environmental quality (IEQ). However, many existing solutions remain expensive, invasive and inflexible. This paper presents the design and validation of a compact, low-cost, and real-time sensor system, conceived for seamless integration into indoor environments. The system measures key parameters—including air temperature, relative humidity, illuminance, air quality, and sound pressure level—and is embeddable in standard office equipment with minimal impact. Leveraging 3D printing and open-source hardware/software, the proposed solution offers high affordability (approx. EUR 33), scalability, and potential for workspace retrofits. To assess the system’s performance and relevance, dynamic simulations were conducted to evaluate metrics such as the Mean Radiant Temperature (MRT) and illuminance in an open office layout. In addition, field tests with a functional prototype enabled model validation through on-site measured data. The results highlighted significant local discrepancies—up to 6.9 °C in MRT and 28 klx in illuminance—compared to average conditions, with direct implications for thermal and visual comfort. These findings demonstrate the system’s capacity to support high-resolution environmental monitoring within IoT-enabled buildings, offering a practical path toward the data-driven optimization of occupant comfort and energy efficiency. Full article

With the deepening implementation of the coordinated development strategy for energy exploitation and ecological conservation, green coal mining technology has become a critical pathway to achieve balanced resource development and environmental protection. This study investigates the stress field evolution and dynamic fracture propagation mechanisms in overlying strata during shallow coal seam mining in the Shenfu mining area. By employing a multidisciplinary approach combining triaxial compression tests (0–15 MPa confining pressure), scanning electron microscopy (SEM) microstructural characterization, elastoplastic theoretical modeling, and FLAC3D numerical simulations, the synergistic failure mechanisms of overlying strata were systematically revealed. Gradient-controlled triaxial tests demonstrated significant variations in stress-strain responses across lithological types. Notably, Class IV sandstone exhibited exceptional uniaxial compressive strength of 106.7 MPa under zero confining pressure, surpassing the average strength of Class I–III sandstones (86.2 MPa) by 23.6%, attributable to its highly compacted grain structure. A nonlinear regression-derived linear strengthening model quantified that each 1 MPa increase in confining pressure enhanced axial peak stress by 4.2%. SEM microstructural analysis established critical linkages between microcrack networks/grain-boundary slippage at the mesoscale and macroscopic brittle failure patterns. Numerical simulations demonstrated that strata failure manifests as tensile-shear composite fractures, with lateral crack propagation inducing bed separation spaces. The stress field exhibited spatiotemporal heterogeneity, with maximum principal stress concentrating near the initial mining cut during early excavation. Fractures propagated obliquely at angles of 55–65° to the horizontal plane in an ‘inverted V’ pattern from the goaf boundaries, extending vertically 12–18 m before transitioning to the bent zone, ultimately forming a characteristic three-zone structure. Experimental and simulated vertical stress distributions showed minimal deviation (≤2.8%), confirming constitutive model reliability. This research quantitatively characterizes the spatiotemporal synergy of strata failure mechanisms in ecologically vulnerable northwestern China, proposing a confining pressure-effect quantification model for support parameter optimization. The revealed fracture dynamics provide critical insights for determining ecological restoration timelines, while establishing a novel theoretical framework for optimizing green mining systems and mitigating ecological damage in the Shenfu mining area. Full article

The combination of electrochemical, surface, and spectroscopic techniques revealed that Pseudomonas aeruginosa biofilm accelerated corrosion of 304 stainless steel (SS), leading to localized pitting with depths up to 3.75 μm. Such damage did not occur on 304 SS treated with P. aeruginosa in the presence of Artemisia annua L. extract, or in sterile seawater. Introducing A. annua into biotic seawater hindered biofilm development and prevented the formation of porous Fe(III) corrosion products. Instead, a compact Fe₃O₄ layer formed, indicating a shift in corrosion product morphology and stability. ATR-FTIR analysis confirmed phenolic groups from the extract were adsorbed onto the steel interface, supporting the dual inhibitory role of A. annua through both surface modification and antimicrobial action. A. annua extract demonstrated a 74.4 ± 4.4% reduction in MIC-induced corrosion of 304 SS in marine conditions. Full article

With the increasing demand for soil modification technologies in the field of civil engineering, this study employed cement-stabilized soil and MBER (Material Becoming Earth into Rock) stabilized soil as controls to investigate the modification effects of an N-MBER (nanosilica reinforced MBER) stabilizer on the mechanical properties and microstructure of loess. The mechanical and water stability characteristics of N-MBER-stabilized loess under varying moisture contents and compaction degrees were analyzed through unconfined compressive strength (UCS) tests, softening coefficient tests, falling-head permeability tests, and wet–dry cycle tests. Combined with scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance (NMR) techniques, the underlying mechanism of the N-MBER stabilizer in loess stabilization was thoroughly revealed. The results indicate that the N-MBER stabilizer significantly enhances the UCS and softening coefficient of loess. Particularly, under conditions of 28-day curing, a moisture content of 16%, and a compaction degree of 1, the compressive strength achieves a local optimum value of 3.68 MPa. Compared to soils stabilized with MBER stabilizers and cement stabilizers, the N-MBER-stabilized loess exhibits superior water resistance and microstructural density, with a significant reduction in the proportion of pore defects. Specifically, after five wet–dry cycles at a curing age of 28 days, the strength loss rates for MBER-stabilized soil and cement-stabilized soil were 24.4% and 27.54%, respectively, while that for N-MBER-stabilized soil was 18.23%, demonstrating its enhanced water resistance. Additionally, compared to cement-stabilized soil, the N-MBER-stabilized soil exhibited a 21.63% reduction in total pore number, with a 41.64% reduction specifically in large pores. The extremely small particle size and large specific surface area of the nanomaterial enable more effective interactions with soil particles, promoting hydration reactions. The resulting ettringite (AFt) and three-dimensional networked C-S-H gel tightly interweave with soil particles, forming a stable cemented structure. Compared to traditional concrete roads, stabilized soil roads enable the utilization of locally available materials and demonstrate a significant cost advantage. This study provides theoretical support and experimental evidence for the application of nanomaterials in loess improvement engineering. Full article

Edge computing offers low-latency and distributed processing for IoT applications but poses new security challenges, due to limited resources and decentralized data. Intrusion detection systems (IDSs) are essential for real-time threat monitoring, yet traditional IDS frameworks often struggle in edge environments, failing to meet efficiency requirements. This paper presents an efficient intrusion detection framework that integrates spatiotemporal hashing, federated learning, and fast K-nearest neighbor (KNN) retrieval. A hashing neural network encodes network traffic into compact binary codes, enabling low-overhead similarity comparison via Hamming distance. To support scalable retrieval, multi-index hashing is applied for sublinear KNN searching. Additionally, we propose an attention-guided federated aggregation strategy that dynamically adjusts client contributions, reducing communication costs. Our experiments on benchmark datasets demonstrate that our method achieves competitive detection accuracy with significantly lower computational, memory, and communication overhead, making it well-suited for edge-based deployment. Full article

Access to schools is crucial in determining an area’s functioning and development, especially regarding housing development. This article presents an analysis of the spatial accessibility of educational services in the city. In Poland, municipalities applied standards for the accessibility of schools in the 1980s and 1990s. In 2023, amendments to the Law on Planning and Spatial Development (The Act of 7 July 2023 amending the Act on Spatial Planning and Development and certain other Acts) reintroduced the obligation to consider the accessibility of education services in the planning documents of municipalities and established the applicable distances. This article presents a method for assessing the level of accessibility of primary schools using spatial–statistical indicators, with the city of Płock as an example. The analysis allowed us to present the spatial differentiation of the level of fulfilment and the level of fulfilment of needs according to the new planning guidelines. We deepened the analysis grounded in the 15-Min City concept to validate the findings, benchmarking the results against international frameworks and recognised good practices. Similar analysis can support local authorities of other municipalities in the spatial planning decision-making process. The authors formulated the following research questions: What criteria can be applied to evaluate the performance of existing educational facilities and determine optimal locations for new schools in planning educational services? Do time-based (15 min) benchmarks reveal different patterns than distance-only thresholds? The example of Płock shows the weaknesses of applying unified urban standards in areas with diverse types of spatial development and the need to modify them. To deepen the verification of the observed discrepancies, the study was extended to include an analysis based on the concept of the 15-Min City. The results revealed even greater disparities in accessibility, highlighting a strong contrast between central and peripheral districts. These findings remain consistent with the conclusions of international studies. Meanwhile, the applicable regulations in Poland provide relatively liberal accessibility thresholds. It may lead to an increase in the distance between residential development and educational facilities and other key elements of urban social infrastructure, thereby distancing national urban planning practices from the European principles of compact, 15 min, and sustainable cities. Full article

Background and Objectives: Laparoscopic surgery has evolved with the integration of robotic systems, offering enhanced precision and ergonomic benefits. However, conventional robotic systems often lack haptic feedback and are associated with high cost. The Saroa surgical system is a compact, pneumatically driven robot that integrates real-time haptic feedback, potentially addressing the limitations associated with conventional robotic systems. This preliminary study reports the first clinical use of the Saroa system in gynecologic surgery, aiming to assess its feasibility, safety, and usability in robot-assisted hysterectomy. Materials and Methods: Five patients underwent robot-assisted total laparoscopic hysterectomy using the Saroa surgical system. The clinical outcomes, setup and console times, estimated blood loss, and subjective surgeon evaluation were recorded. Results: All surgeries were successfully completed without any intraoperative complications or the need for conversion to conventional surgery. The median setup time was 12 min, the console time was 211 min, and the median blood loss was 80 mL. Surgeons subjectively noted that the system’s real-time haptic feedback substantially improved precision during vaginal cuff tissue manipulation, based on their tactile sensation and real-time force display, thereby reducing the perceived risk of traction-related tissue injuries. Conclusions: This study represents the first clinical application of the Saroa surgical system in gynecologic surgery. The findings suggest that the system is feasible and safe for robot-assisted hysterectomy. Despite limitations such as small sample size and the absence of objective force data, the favorable surgeon-reported experience highlights the potential value of haptic feedback in improving surgical performance. These results support further investigation through larger, controlled studies and quantitative performance evaluation. Full article

Strawberry detection in complex orchard environments remains a challenging task due to frequent leaf occlusion, fruit overlap, and illumination variability. To address these challenges, this study presents an improved lightweight detection framework, DS-YOLO, based on YOLOv8n. First, the backbone network of YOLOv8n is replaced with the lightweight StarNet to reduce the number of parameters while preserving the model’s feature representation capability. Second, the Conv and C2f modules in the Neck section are replaced with SlimNeck’s GSConv (hybrid convolution module) and VoVGSCSP (cross-stage partial network) modules, which effectively enhance detection performance and reduce computational burden. Finally, the original CIoU loss function is substituted with WIoUv3 to improve bounding box regression accuracy and overall detection performance. To validate the effectiveness of the proposed improvements, comparative experiments were conducted with six mainstream object detection models, four backbone networks, and five different loss functions. Experimental results demonstrate that the DS-YOLO achieves a 1.7 percentage point increase in mAP50, a 1.5 percentage point improvement in recall, and precision improvement of 1.3 percentage points. In terms of computational efficiency, the number of parameters is reduced from 3.2M to 1.8M, and computational cost decreases from 8.1G to 4.9G, corresponding to reductions of 43% and 40%, respectively. The improved DS-YOLO model enables real-time and accurate detection of strawberry fruits in complex environments with a more compact network architecture, providing valuable technical support for automated strawberry detection and lightweight deployment. Full article

This study presents a comprehensive experimental investigation into the frictional pressure drop of two-phase flows—boiling and condensation—in horizontal minichannels, emphasizing its impact on the energy efficiency of vapor compression systems. A total of 3553 data points were obtained using six low-GWP refrigerants (R32, R134a, R290, R410A, R513A, and R1234yf) across a wide range of operating conditions in multiport aluminum tubes with hydraulic diameters of 0.715 mm and 1.16 mm. The dataset covers mass fluxes from 200 to 1230 $\mathrm{kg}{\mathrm{m}}^{-2}{\mathrm{s}}^{-1}$, saturation temperatures between 5 °C and 55 °C, and vapor qualities from 0.05 to 0.95. Results showed a strong dependence of frictional pressure gradient on vapor quality, mass flux, and channel size. Boiling flows generated higher frictional losses than condensation, and high-density refrigerants such as R32 exhibited the largest pressure penalties, which can directly translate into increased compressor power demand. Conversely, higher saturation temperatures were associated with lower frictional losses, highlighting the role of thermophysical properties in improving energy performance. Additionally, an inverse correlation between saturation temperature and frictional pressure gradient was observed, attributed to variations in thermophysical properties such as viscosity and surface tension. Existing correlations from the literature were assessed against the experimental dataset, with notable deviations observed in several cases, particularly for R134a under high-quality conditions. Consequently, a new empirical correlation was developed for predicting the frictional pressure drop in two-phase flow through minichannels. The proposed model, formulated using a power-law regression approach and incorporating dimensionless parameters, achieved better agreement with the experimental data, reducing prediction error to within ±20%, improving the accuracy for the majority of cases. This work provides a robust and validated dataset for the development and benchmarking of predictive models in compact heat exchanger design. By enabling the more precise estimation of two-phase pressure drops in compact heat exchangers, the findings support the design of refrigeration, air-conditioning, and heat pump systems with minimized flow resistance and reduced auxiliary energy consumption. This contributes to lowering compressor workload, improving coefficient of performance (COP), and it ultimately advances the development of next-generation cooling technologies with enhanced energy efficiency. Full article