Search Results (485)

ETFE cushions are applied to building facades in a wide range of geometric forms and sizes. However, information on how cushion geometry and dimensions affect bulging behavior, thickness and area values, structural strength, thermal conductivity, and energy performance remains limited. Therefore, this study investigates cushion typology in eight geometries (isosceles and equilateral triangle, square, rectangle, rhombus, pentagon, hexagon, circular) with side lengths or radius values between 1 and 10 m, covering 115 variations. Geometric/physical mathematical area calculations, the parabolic dome model, elastic plate bending theory, the empirical thickness model, and thermal-resistance and degree day-based energy calculation approaches are used to obtain planar area, inflated curved surface area, maximum and average thickness, R and U values, and heating, cooling, and total energy consumption for each typology. The use of AI in numerical calculations provides fast and efficient design solutions in architecture and enables various geometric and performance scenarios to be produced rapidly. Circular, hexagon, and pentagon cushions lower U values and provide energy savings due to their high bulging capacity and deformation homogeneity; square, rhombus, and rectangle cushions show medium-level performance; isosceles and equilateral triangles limit energy savings because they produce higher U values. In conclusion, an increase in average bulging thickness and characteristic length reduces the number of cushions required to cover the facade, decreases the U value, reduces total heating and cooling energy consumption, and improves thermal performance. When a facade is covered with cushions of different geometries and sizes, it provides up to approximately 99.24% energy savings. Full article

An ordinary state-based peridynamic (OSPD) approach combined with an interaction integral method is proposed to calculate dynamic stress intensity factors (DSIFs) and simulate crack propagation in two-dimensional cracked brittle solids. Numerical investigations are carried out for mode I and mixed-mode cracked plates under static, quasi-static, and dynamic loading conditions. A local damping scheme is incorporated into the peridynamic equations of motion to achieve convergence in static and quasi-static analyses. The influence of circular holes on DSIFs and crack propagation paths is systematically examined. Quantitative analyses of elastic deformation and quasi-static fracture behavior for mode I and mixed-mode cracks are verified through the uniaxial tension of a slab. The peak values of DSIFs exceed their static counterparts under dynamic loading. Complex dynamic fracture phenomena, including crack branching in both straight and inclined edge cracks, are successfully captured. The results obtained by the OSPD approach are validated through comparisons with theoretical benchmarks and finite element results, demonstrating high accuracy and effectiveness in calculating elastic deformation and stress intensity factors (SIFs), as well as accurately predicting crack propagation paths in quasi-static and dynamic fracture problems in brittle solids. Beyond the benchmark problems, the proposed OSPD approach is particularly well-suited for investigating more complex fracture systems. Full article

This paper presents a wideband pattern-reconfigurable antenna designed for 360° horizontal sensing with angle-of-arrival (AoA) estimation capability. The antenna features a unique three-layer planar architecture, where a microstrip circular array is integrated between two metallic plates to enhance radiation stability and bandwidth. By employing a single-pole four-throw (SP4T) switching circuit, the array generates four steerable beams covering the entire azimuthal plane. Experimental results show that the prototype achieves a 10 dB return loss impedance bandwidth of 50% (4.0–6.0 GHz) and a peak gain of 8.3 dBi. Based on this antenna, a correlation-coefficient-based AoA estimation approach is implemented. The measured results demonstrate reliable estimation performance, with a mean angular error of less than 1.5° over the 360° horizontal plane across the operating frequency range. The proposed design provides a compact and low-complexity solution for practical wideband direction-finding applications in next-generation wireless systems. Full article

This study determines the time period of vibrational modes for a non-uniform orthotropic parallelogram plate, featuring a one-dimensional circular thickness variation and subjected to clamped (CCCC) edges. The authors make assumptions about the material; they assume a one-dimensional circular density variation and incorporate Poisson’s ratio to address material non-uniformity. The motivation to choose circular variation in the plate parameter was due to its numerous applications in engineering and real-life applications like engine covers, rotor blades, etc. The authors also account for a parabolic temperature gradient across the plate. Utilizing the Rayleigh–Ritz technique, they derive the frequency equation and solve it to determine the vibration mode time periods. This study includes a convergence analysis of the plate across (CCCC) edge conditions. The primary aim is to demonstrate the advantage of selecting a variable (circular) density and Poisson’s ratio simultaneously over solely varying the density parameter. The secondary aim is to show that the variable Poisson’s ratio is a much better choice in comparison to variable density as a non-homogeneity parameter. Full article

To investigate the polarization characteristics of AlO molecular emission in femtosecond laser-induced aluminum plasma, AlO molecular spectra were generated by irradiating an aluminum target with a femtosecond laser. The experimental results revealed a pronounced polarization response in the AlO emission. After a polarizer was introduced into the collection path, the signal-to-background ratio (SBR) increased from 8.30 to 10.80, while the relative standard deviation (RSD) decreased from 0.043 to 0.036, indicating improved spectral quality and stability. By modulating the laser polarization state using a half-wave plate and a quarter-wave plate, the AlO spectral intensity increased by a factor of 1.26 when the laser polarization was changed from horizontal to vertical, and by a factor of 1.75 when it was changed from linear to circular. Under circular, horizontal, and vertical polarization conditions, the SBR values obtained with a polarizer were consistently higher than those obtained without a polarizer, with the maximum value of 12.46 achieved under vertical polarization. These results demonstrate that both plasma polarization detection and laser polarization modulation can effectively achieve better-quality AlO molecular spectra. This work provides a useful reference for improving molecular spectral quality in femtosecond laser-induced spectroscopy. Full article

Ochetobibus elongatus (Kner) is a migratory fish found in the Yangtze River basin and areas south of it, and listed as a critically endangered (CR) fish on the China Red List of Vertebrates. To achieve group recovery and artificial breeding, this study investigated the dietary characteristics of O. elongatus based on high-throughput sequencing of its intestinal contents, and its digestive system morphology, and its histology. Results showed that the digestive system of O. elongatus lacked a stomach and mainly consisted of the oropharynx, pharyngeal teeth, esophagus, intestine, and anus. The gut index was 0.88, with clear segmentation of the foregut, midgut, and hindgut, and the visceral mass index was 7.35%. Histological analysis of the digestive system revealed the presence of keratinized dental plates or pharyngeal teeth in the pharynx, as well as a high density of taste bud cells in the soft palate of the oral cavity. The surface layer of the intestinal villi contained numerous mucous cells, with the average number of mucous cells per villus gradually increasing from the esophagus to the hindgut, and the foregut having the longest and most abundant mucosal folds. The esophagus exhibited well-developed circular and longitudinal muscle layers, while in the hindgut, both the circular and longitudinal muscle layers were slightly thicker than those in the midgut. High-throughput sequencing of the intestinal contents of O. elongatus revealed the following phyla based on 18S V4 meta-barcoding: Chlorophyta, Diatoms, Arthropoda, Basidiomycetes, and Ascomycetes, with the genus Hypophthalmichthys and algae being the main classifications. In contrast, based on COI meta-barcoding, the study newly identified the phyla Cnidaria and Mollusca, with the genera Chlorophyta, Scenedesmus, Pectinodesmus, and zooplankton such as Pseudodiaptomus. Metagenomic sequencing revealed that the gut microbiota at the phylum level was predominantly composed of Pseudomonadota, Ascomycota, Basidiomycota, Chytridiomycota, and Bacillota, with key genera including Cetobacter, Pseudomonas, Acinetobacter, Aeromonas, and Clostridium. This study indicates that O. elongatus is an omnivore with carnivorous tendencies. Basic biological research on O. elongatus is of great significance for the restoration of the population, artificial breeding, and the development of its artificially formulated feed. It also provides important data for the formulation of biodiversity conservation measures. Full article

In this study, composite plates with circular holes cracked on both edges were repaired using a composite patch. Epoxy adhesive was used to bond the patch to the plate. Low-velocity impact tests were applied to repaired specimens with varying crack lengths. Compared to specimens without holes, the maximum reaction force of repaired specimens without cracks increased by up to 50%. When the crack length reached its maximum, the maximum impact force of repaired specimens increased by 36% compared to the specimens without holes. Full article

Sometimes only a portion of the surface of a concrete element is loaded, which causes stress concentration in that region. To safely transfer concentric loads to concrete components such as column bases, short cantilevers, superstructure piers, post-tensioned elements, and support anchors, it is imperative to investigate the local compressive characteristics of concrete. To learn more about this subject, further research is required, as there are currently insufficient studies in this field. Therefore, the local compressive behavior of concrete under concentric stresses is the main focus of this work. Concrete is represented as block samples with dimensions of 200 × 200 × 250 mm. A stiff steel plate is used to apply concentric loading on the surface of the samples. The primary parameters are the bearing plate dimensions, shape (square, rectangle, and circular with varying areas), and rectangularity. Additionally, the bearing plate’s movement is examined. The stress-slip curves, ultimate bearing strengths, failures, and related slippages of the tested samples are discussed. The findings revealed that the upper surface of the concrete samples exhibited localized deterioration beneath the bearing plate. Additionally, the ultimate bearing strength of the sample loaded with the 6 × 6 cm square plate was 163% greater than that of the sample loaded with the 10 × 10 cm square plate. Furthermore, the sample loaded with the circular plate with a diameter of 4 cm had an ultimate bearing strength that was 181% greater than the sample loaded with the circular plate with a diameter of 11 cm. It is clear that the samples loaded with a circular plate of varying diameters had an ultimate bearing strength that was 8.5–11% higher than the samples loaded with a square plate of varying lengths. Full article

Efficient thermal management is critical for maintaining the safety, durability, and performance of lithium-ion batteries used in electric vehicles (EVs). In this study, a comprehensive numerical investigation is conducted to evaluate the heat transfer characteristics of mono- and hybrid-nanofluids in a microchannel-cooled lithium-ion battery module. A three-dimensional computational model of a 5S7P battery module composed of cylindrical 21700 cells is developed. Battery heat generation during 3C high discharge rate operation is predicted using the Newman-Tiedemann-Gu-Kim (NTGK) electrochemical model, while coolant flow and heat transfer are simulated using the governing conservation equations for mass, momentum, and energy. The cooling system consists of six liquid-cooling plates with circular microchannels. The performance of water-glycol (50/50) coolant is compared with several mono nanofluids of Al₂O₃ and Cu, and hybrid nanofluids of Al₂O₃-Cu, Al₂O₃-MWCNT, Al₂O₃-Graphene, Cu-MWCNT, and Cu-Graphene across multiple coolant flow rates from 1–5 LPM. The results demonstrate that nanofluids significantly enhance convective heat transfer and reduce battery temperature compared with the conventional water-glycol coolant. Among the investigated coolants, the Al₂O₃-Cu hybrid nanofluid (0.45–0.45%) operating at 1 LPM achieves the best overall thermo-hydraulic performance with a performance evaluation criterion (PEC) of 1.065. Further analysis of nanoparticle composition ratios shows that a Cu-dominant hybrid mixture (Al₂O₃-Cu: 0.27–0.63%) slightly improves the PEC to 1.0657, indicating marginally superior cooling performance. The findings highlight the potential of hybrid nanofluids as advanced coolants for microchannel-based battery thermal management systems in EVs, particularly under moderate coolant flow conditions. Full article

The present paper addresses the experimental measurement of vibration frequencies using an earth pressure sensor embedded in a full-scale (1:1) test structure. The vibration frequencies within the tested structure were induced by static load tests carried out at different elevation levels (corresponding to varying thicknesses of the crushed aggregate layer) in accordance with the methodology applied on German railways (DIN 18 134). The aim of the research was to verify the stress state at individual partial levels of the tested structure on the basis of the measured vibration frequencies, and to determine the depth of influence and the load dispersion angle generated by the static load test (SLT). The measured parameters also serve as input data for parallel research focused on the assessment of transition zones between railway embankments and artificial structures along railway lines. The results presented in this paper indicate that the stress induced by the SLT decreases with increasing structural thickness of the tested construction. For a structural layer thickness of 150 mm, the resulting stress corresponds to approximately 63% of the stress value (force effect) induced on a rigid circular plate (σ = 0.50 MPa), whereas for a layer thickness of 900 mm, the stress corresponds to approximately 12% of that value. The force (stress) effects of the SLT cease to act at a depth between 900 and 950 mm (only stress due to the self-weight of the overlying material was recorded), and the load dispersion angle is approximately 40°. Full article

In karst tunnel engineering, water-filled cavities located above the tunnel crown, under the combined effects of excavation disturbance and hydraulic pressure, are prone to triggering water and mud inrush disasters. The thickness of the water-resisting rock layer is therefore a key factor controlling the stability of the surrounding rock. To address the difficulty in accurately characterizing the mechanical behavior of the crown of horseshoe-shaped tunnels using conventional circular plate or beam models, this study innovatively develops an explicit analytical model for the minimum safe thickness of the water-resisting rock layer based on clamped elliptical thin plate theory and Kirchhoff plate theory, incorporating the influence of cross-sectional geometry. Parametric sensitivity analysis indicates that both karst water pressure and tunnel crown height significantly amplify the required minimum safe thickness, whereas an increase in the tensile strength of the surrounding rock effectively reduces the thickness demand. Specifically, when the karst water pressure increases from 2.5 MPa to 4.5 MPa, the minimum safe thickness rises from 7.5 m to 10.0 m, showing an approximately linear growth trend. The analytical model is further validated through numerical simulations under different “water pressure–thickness” conditions. The results demonstrate that at the calculated recommended thickness, the surrounding rock achieves stable convergence after excavation. High tensile stress and elevated pore pressure zones are mainly concentrated near the tunnel crown, without the formation of through-going tensile failure. Engineering application indicates that the proposed model can provide a quantitative basis for the design of water-resisting rock layer thickness and the assessment of water inrush risk in karst tunnels. Full article

Composite soil–steel corrugated bridges, which are widely used in road, railway, and civil engineering, are recognized as durable, sustainable, and cost-effective structures. Due to their interactions with the surrounding soil, relatively thin corrugated steel plates are usually used in these bridges. Larger spans are associated with larger cross-sections, and deep corrugations with a 500 mm pitch and a 237 mm depth are already in use worldwide. However, the behavioral benefits of high-strength steel and additional strengthening elements for CSS structures have rarely been investigated with regard to local buckling in the straight regions of the corrugation. This study analyzed the influence of high-strength steel and innovative corrugated cross-sections strengthened with circular steel pipes on the utilization ratio of steel plates in composite soil–steel structures. Two-dimensional numerical models of three bridges with spans of 26 m, 17.5 m, and 12 m and surrounded by soil were developed to identify internal forces from permanent and temporary actions. Plate utilization was designed according to the Swedish, Canadian, and American methods, considering local buckling in the 500 × 237 mm and 381 × 140 mm corrugation profiles. It was found that the use of higher-strength steel material, as well as the introduction of steel pipes, significantly reduced the plate thickness of regular corrugations. The results show that the use of higher-strength steel reduced the cross-section area of regular and innovative corrugations by 30–40%. Moreover, the cross-section area of the innovative profile was 5% to 36% lower than that of the regular corrugation profile. Nevertheless, the results show that the local buckling approach proposed by the Swedish design method could be considered conservative and should be revised. In addition, the method of preventing local buckling by reducing the plastic moment capacity could be neglected when using thicker plates and lower steel grades. Full article

A cost-effective and practical method for characterizing the dielectric properties of liquids at 1 MHz is presented in this article. A cylindrical parallel-plate capacitive sensor was developed, in which the circular end plates function as electrodes and the sidewall is formed by a thin polyvinyl chloride ring cut from a standard water pipe to enclose the liquid sample. Dielectric constant values of air, distilled water, ethanol, and methanol were determined through analytical calculations, electromagnetic simulations, and experimental measurements at 1 megahertz. Consistent results were obtained across all methods, and the extracted values were found to agree well with theoretical values, yielding extraction errors of 0.06% for methanol and 1.85% for ethanol with respect to theoretical values from the literature. A calibration technique was applied in which air and water were used as reference materials with known dielectric constants, effectively mitigating uncertainties associated with sensor geometry, spacer material, and fringing fields. Through this work, a practical and effective technique for dielectric characterization at low frequency has been demonstrated, with core validation of four reference materials (air, deionized water, ethanol, and methanol) at 1 MHz and an additional application example in which cow’s milk is characterized over 10–30 MHz. The 10–30 MHz measurement demonstrates the applicability of the proposed method in the low megahertz region, while the primary validation is conducted at 1 MHz. The technique is applicable to a wide range of applications in materials science, chemical, and biomedical engineering. Full article

To realize high heat transfer capacity with low energy consumption in machine tool thermal control systems under high-flow-rate conditions, a vortex-inducing–microchannel composite enhanced thermal control plate is proposed. Numerical simulations combined with experimental validation are conducted to investigate the effects of vortex-inducing geometry and microchannel configuration under unified boundary conditions. Heat transfer capacity, pressure drop, coefficient of performance (COP), and performance evaluation criterion (PEC) are employed for comprehensive assessment. The results show that vortex induction enhances fluid mixing and boundary layer renewal, while microchannels effectively suppress pressure loss and energy consumption. Their synergistic coupling enables a balanced optimization between heat transfer enhancement and flow resistance control. Compared with a conventional thermal control plate, the proposed composite structure achieves over 20% improvement in heat transfer capacity and more than 50% increase in COP within the tested operating range. Among the investigated configurations, circular and square vortex-inducing structures combined with microchannels exhibit superior overall performance, with the circular configuration reaching a maximum COP enhancement of 72% at a flow rate of 7 L/min. This study provides practical guidance for structural selection and parameter optimization of composite thermal control plates for machine tools. Full article

Rayleigh–Bénard convection (RBC) provides a benchmark for studying buoyancy-driven instabilities and heat transport in confined fluids. Heat transfer scaling in cylindrical geometries is well established, whereas the role of the anisotropy induced by the domain geometry, such as elliptical shapes, has not fully explored. This study presents direct numerical simulations of RBC in two domains of equal height, $H=0.0124$ m, and different cross-sections: a circular cylinder with radius ${\displaystyle R=3.11\times {10}^{-3}}$ m and an elliptical cylinder with semi-axes equal to ${\displaystyle R_{\max }=3.11\times {10}^{-3}}$ m, ${\displaystyle R_{\min }=1.55\times {10}^{-3}}$ m, respectively. The simulations, performed at Rayleigh number $\mathit{Ra}=2\times {10}^6$ and Prandtl number $\mathit{Pr}=1.68$ (for water) under the Boussinesq approximation, reveal that (i) the average Nusselt number is comparable in both cases ($⟨\mathit{Nu}⟩\approx 38.23$ for the circular case and $⟨\mathit{Nu}⟩\approx 39.22$ for the elliptical one) and (ii) the different domain geometries influence the thermal transport mechanism and flow organization. Specifically, in the cylindrical cell, heat transfer is regulated by a large-scale circulation roll, whereas in the case of the elliptical shape, the domain is populated by thermal plumes driving the convective dynamics. The latter phenomenon is evidenced by larger Nusselt number fluctuations at the lower and upper plates, with a standard deviation increasing from $\sigma \approx 2.21$ in the circular cylinder to $\sigma \approx 4.57$ in the elliptical domain. These results highlight that the geometric anisotropy modifies the coupling between boundary layers and the core flow dynamics, leading to enhanced intermittency without affecting the magnitude of the heat flux. Therefore, the elliptical domain is suitable for applications characterized by enhanced mixing. Full article