Cross-sectional Structure Research Articles

Hydrogen sensing performance and stability of WO3–SiO2 composite film doped with Pt catalyst

AbstractHydrogen energy has attracted attention as a new energy carrier because it does not generate CO2 emissions during combustion. However, numerous problems face the establishment of a hydrogen infrastructure society. One problem is safety when using hydrogen. A fast sensing system for hydrogen at low concentrations will be needed for hydrogen to be used safely. WO3 is expected to be used as an optical hydrogen sensor element because it reacts with hydrogen and changes color. We prepared Pt-doped WO3 films by the sol–gel method using an ion-exchange technique under various experimental conditions and investigated the films’ response properties to hydrogen and their morphology. As a result, a Pt/WO3 film with SiO2 (Pt/WO3–SiO2 film) annealed at 200 °C showed the shortest coloring and bleaching time to 4 vol% hydrogen. The films also showed good reproducibility with respect to their hydrogen response and good long-term stability. In addition, the fast bleaching time led to a stable repeated response, enabling the films to be used in real-time monitoring applications. Moreover, the sensitivity of the Pt/WO3–SiO2 films depended on the hydrogen concentration, which suggested that quantitative sensing of hydrogen at concentrations below the lower explosive limit could be realized. Furthermore, the catalyst Pt active state and the difference in gas diffusivity due to the microstructure of the films were considered through analysis of the surface, cross-sectional structure, and elemental state of the films. Graphical Abstract

Hydrophobicity of periodic structure with taper angle under pressure impact

Biomimetic periodic structures have garnered attention due to their excellent water repellency. The normal-taper angle, which is aspects of the cross-sectional structure, is important factor in achieving water repellency and pressure resistance; however, the underlying physical phenomenon has not been fully explained. Moreover, once a surface becomes hydrophobic, it is difficult to measure the apparent contact angle. The purpose of this paper is to clarify the taper angle that provides high water repellency under pressure impact conditions by formulating the relationship between the taper angle and the height of a droplet bouncing, instead of traditional contact angles, using experimental results. We fabricated multiple samples with different taper angles and groove width/tooth width ratios, through micro-processing using a femtosecond-pulsed laser and a control algorithm, and investigated their effects on water repellency. By using height of a droplet bouncing as an evaluation parameter, we were able to effectively differentiate between taper angles in terms of water repellency. Additionally, we suggested that in the bouncing phenomenon, where droplets are given velocity by falling, the sidewall of the periodic structure and the taper angle affect liquid repellency. To explain this phenomenon, we proposed a pressured-taper angle model where a droplet is pressed against the taper angle. Based on both experimental findings and the pressured-taper angle model, a relationship between the equilibrium contact angle, the taper angle, and the lifting force angle was revealed. Moreover, using this pressured-taper angle model, the taper angle of the periodic structure to achieve maximum liquid repellency was estimated from the equilibrium contact angle of the base material.

Microstructure evaluation of Si-modified aluminide coatings on IN625 deposited by slurry aluminizing process

Si-modified aluminide coatings are promising for improving oxidation and corrosion resistance in superalloys at high temperatures. This study investigated the effect of different silicon levels in the aluminizing slurry on the morphology and structure of Si-modified aluminide coatings on IN625. This process involved spraying a slurry of aluminum and silicon particles in an aqueous PVA solution onto IN625 samples, followed by heat treatment under controlled conditions - two atmospheres (air and argon) and two heating ramps (regular and flash). Surface morphologies, cross-sectional structures, elemental compositions, and phase formations were analyzed using FE-SEM, SEM, EDS, and XRD methods, while DTA analysis assessed AlSi alloy formation during heating. The results showed that higher silicon content in the slurry increased silicon incorporation in the coatings but did not reduce aluminum activity enough to deposit a low-activity aluminide coating. The inert atmosphere (argon) and flash heating promoted the co-deposition of Si and Al, resulting in Cr and Mo silicide-enriched outer layers in some samples. The aluminum content in all slurries was sufficient for consistent β-NiAl formation across different silicon levels. The average silicon content in coatings ranged from 5 to 15 wt% and depended on the slurry composition and heat treatment conditions. The Al30Si slurry produced the thickest coatings (~90 μm), with further increases in Si leading to reduced thickness. This study suggests that slurry aluminizing can be optimized to control silicon incorporation, depositing Si-modified aluminide coatings for durable, high-performance applications.

Superinertial Internal Tides Propagating along the Coast: Dynamics and Energetics Revealed through Topographic Modes

Abstract Internal tides are an important energy source for diapycnal mixing in the ocean interior. Subinertial internal tides are known to have a cross-sectional structure that is baroclinic in deep areas but more barotropic in shallower areas, making the conventional barotropic–baroclinic decomposition ineffective to separate internal tides from surface tides. To address this issue, Tanaka introduced a “topographic mode” which represents internal motions with a barotropic vertical structure and proposed a new energy diagram enabling us to quantify the generation of subinertial internal tides. Here, the applicability of this new energy diagram to superinertial internal tides at various latitudes is investigated by idealized numerical experiments with uniform surface tides passing over a continental slope with a bump in the coastline. The calculated results show that both the topographic and baroclinic modes are generated over the bump and propagate downstream along the coast, inseparably forming a topographically modified internal Kelvin wave whose cross-sectional structure closely resembles that obtained by solving a two-dimensional eigenvalue problem for a superinertial frequency. The energy conversion rate from the surface mode to the topographic mode is about half of the energy conversion rate from the surface mode to the baroclinic mode when the tidal frequency is slightly superinertial and maintains a nonnegligible contribution even when the tidal frequency is substantially superinertial. The findings of this study indicate that the new energy diagram can be applied seamlessly across the critical latitudes and possibly provides a global distribution of the internal tide generation significantly larger than the previous estimates. Significance Statement Quantifying the generation of internal tides is essential for accurate climate modeling, since they are a major energy source of vertical mixing in the ocean. It is known that diurnal internal tides change their characteristics poleward of 30° latitude, where their motion is dominated by horizontal rotation rather than vertical oscillation. This study demonstrates that a recently proposed energy diagram for quantifying the generation of diurnal internal tides poleward of 30° latitude is also effective equatorward of 30° latitude. This is because the rotational motion remains significant even equatorward of 30° latitude, being a fundamental component of the internal tides over a sloping seafloor. The application of this energy diagram will improve the global estimate of internal tide generation.

Waveguide finite element modelling for broadband vibration analysis of tyres including rotation and prestress

In the framework of tyre/road noise prediction, our aim is to introduce a waveguide finite element (WFE) method for broadband vibration analysis of rotating inflated structures of arbitrary cross-section. Approximating the geometry as perfectly circular, the finite element discretization is restricted to the two-dimensional cross-section, enabling fast and high-frequency computations. Tyres are particularly challenging to model due to various complicating effects, often approximated or neglected in WFE models : rotation, inflation, structural anisotropy, heterogenetity, damping among others. Our formulation uses Lagrangian perturbations of displacement in Eulerian coordinates, providing a concise way to express equilibrium equations in vibrating media initially moving, prestressed and subjected to fixed point forces (typically, contact excitations in rotating tyres). The method comprises three steps: computing the steady rolling state (including rotation, inflation and centrifugal force), determining the undamped vibration modes superimposed onto the steady state (solving an eigenvalue problem of quadratic type owing to Coriolis acceleration), and obtaining the forced response of the damped structure through specific orthogonality relationships (considering a specific form of damping). The WFE method is compared with a rotating shell analytical model from existing literature and is subsequently applied to a rotating tyre with heterogeneous cross-section up to 4kHz.

Are some piece rates better than others? Cross-sectional variation in piece rates at a US cotton factory

While piece rates were a common form of payment in manufacturing, historians have rarely tried to understand the cross-sectional structure of piece-rate prices. This paper examines piece rates paid to weavers at a US cotton factory and demonstrates that in most cases expected daily earnings were constant across different piece rates. While some rates did result in higher daily earnings, there is no evidence of gender discrimination in the assignment of such rates.

The Lacquer Craft of the Corridor Coffin (徼道棺) from Tomb No. 2 of Tushan in Eastern Han Dynasty, Xuzhou

Tomb No. 2 of Tushan in Xuzhou is the tomb of King Chu of the Eastern Han Dynasty, and it was an important archaeological discovery in China. The unique placement and crafting techniques of a lacquer coffin that was unearthed from the burial corridor are of significant importance in the study of tombs. In order to characterise the sample’s microstructure, elemental composition, and structural composition, as well as to study the crafting techniques of the coffin in the corridor, a range of analytical techniques were employed, including ultra-depth microscopy, scanning electron microscopy with SEM-EDS, Raman spectroscopy, FTIR, and XRD. The results indicate that the cross-sectional structure of the fragments comprises a pigment layer and a lacquer ash layer, with the latter being further divided into tile ash and bone ash layers. No lacquer film layer was observed. The primary colouring agent in the pigment layer was HgS, which contained a minor quantity of organic binder. The primary component of the tile ash layer was quartz, while the osseous ash layer comprised particles and collagen derived from mammalian bones. The lacquer crafting technique employed in the construction of the coffin was relatively simple and inconsistent with the assumption of it having a noble status. The findings of this research offer experimental data for the identification, preservation, and technical restoration of the corridor coffin in the future.

A new shape reconstruction method for monitoring the large deformations of offshore wind turbine towers

Offshore wind turbine (OWT) upsizing has become an inevitable trend. Compared with small OWTs, large OWT rotors exert greater horizontal loads and bending moments on the tower. These factors make a large OWT tower more prone to geometric nonlinear deformations, which can affect the normal operation of a wind turbine and even lead to damage to the wind turbine tower. Therefore, monitoring the deformation of large OWT towers is necessary. Shape sensing is a technique that uses surface strains to reconstruct deformed shapes. Currently, there is a lack of effective methods for geometric nonlinearity deformation shape sensing. In addition, the tower of OWT is a variable cross-section structure. The influence of varying cross-sections further increases the difficulty of developing a large deformation reconstruction algorithm. To solve this problem, this paper proposes a new method called rotation angle approximation (RAA). This method establishes a least-squares error functional using analytic curvature and section curvature. The rotation angles of the tower axis are obtained via this function. The deformed shape is then predicted via the boundary conditions and the rotation angles along the tower axis. Numerical simulations demonstrated this method can accurately predict the large deformations of a tower under different load conditions.

Development and characterization of bilayer chitosan/alginate cling film reinforced with essential oil based nanocomposite for red meat preservation

With a goal to finding suitable alternatives to plastic packaging in the food industry, we developed a multifunctional bio-based active packaging film to enhance the shelf life of red meat. A chitosan/alginate (Chi + Alg) bilayer film was developed through layer-by-layer (LBL) assembly and an active material i.e. lemongrass nanoemulsion with silver nanoparticles-based nanocomposite (NC1) was loaded into the alginate layer to improve the quality of the bio-based film (Chi + Alg + NC1). The Chi + Alg + NC1 film was characterized in terms of its microstructure, mechanical strength, thermal stability, and antimicrobial activity. Scanning electron microscopy (SEM) revealed a film (22.5 ± 1.44 μm thickness) with a smooth and even surface and a cross-sectional structure. The incorporation of NC1 improves the quality of the film by enhancing its mechanical strength and thermal stability. FT-IR spectra showed the successful interaction between chitosan and alginate in the LBL assembly and the incorporation of NC1 in the alginate layer. The red meat preservation test demonstrated that the shelf life improved when the meat was covered with the fabricated bio-based film. The color of the meat was retained for up to 7 days compared to that of the control (Chi alone and Chi + Alg). Additionally, a reduction in the microbial count in the Chi + Alg + NC1 film was observed, corroborating the shelf-life improvement. In addition to its inherent antimicrobial properties, NC1 induced hydrophilic properties to the film, which further aids in its antimicrobial activity against E. coli. These findings suggest that Chi + Alg + NC1 film could be a potent alternative to plastic packaging and can be used as a cling film to prolong the shelf life of red meat.

Response of variation of electrical control parameters to coatings prepared in organo-silicon electrolyte by plasma electrolytic oxidation

This study aims to explore the influence of control parameters from the perspective of the amorphous ceramic coating formation process. Three preparation processes were preferred based on the thickness, appearance and corrosion resistance of the coatings by orthogonal experiment. The surface morphology, cross-sectional structure, phase composition and micro-hardness of PEO coatings were examined using scanning electron microscopy (SEM)/Energy dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD) and hardness measurement techniques. Findings indicate that voltage exerts the most significant impact on coating thickness and appearance, whereas the influence of other parameters becomes more pronounced as the voltage increases. Three amorphous ceramic coatings prepared in 20 min with thicknesses of 27.4 μm, 83.2 μm and 193.3 μm increased the surface hardness of 6061 aluminium alloy by 6–8 times, and decreased the corrosion current density of 6061 aluminium alloy by 3 orders of magnitude in 1 mol L−1 HCl solution. Moreover, the thickening of the coating primarily occurs within a few minutes after the voltage reaches its peak, and high frequency and low duty ratio are prerequisites for better appearance under higher voltage conditions.

Thin-Layer TiO2 Membrane Fabrication by Condensed Layer Deposition.

A novel approach to the fabrication of thin-film supported metal oxide membranes was investigated. Nanocoatings were obtained by the condensed layer deposition of TiO2 on tubular microporous supports, applying multiple consecutive layers of TiO2/polyaniline. The surface, cross-sectional structure, and morphology of the materials were investigated by electron microscopy. Their membrane-related properties were explored by permeability measurements, rejection, and fouling analysis, using polyethylene glycol (PEG) as test molecules. The SEM images showed that TiO2 was successfully deposited on the surface, creating a layer with partial coverage of the support after each layer was deposited; consequently, the permeability of the membranes decreased gradually. Overall, the results of the flux and permeability of the membranes confirmed the coating. The transmembrane pressure (TMP) increased with each coating layer, while the rejection of the membrane showed gradual improvement.

A novel nonlinear pressurization method for counter-gravity casting of cross-sectional mutation structures

In order to ensure the filling integrity of complex counter-gravity casting and improve metallurgical quality, it is necessary to shorten the filling time while avoiding air entrainments. To address this contradiction, a novel nonlinear pressurization method was proposed in this study. Through systematically analyzing the relationship between critical gating velocity and stable filling height, a criterion for iterative calculation of nonlinear pressurization curve was established, and an empirical expression between nonlinear pressurizing speed and the filling height was obtained. Based on the empirical expression, a nonlinear pressurization curve can be designed according to the casting structures and initial pressurizing speeds. The above nonlinear pressure curve design method was validated through water filling experiments. It was proved that the nonlinear pressure curve can shorten the filling time while avoiding air entrainments. It provides important processing control method for improving the low-pressure casting performance of complex castings.

Effect of three-dimensionality of turbulence on the along-wind loads of square cross-sectional structures

The existing theories for along-wind loads on slender structures, based on the “strip assumption” overlook the three-dimensionality of turbulence. However, numerous experimental phenomena contradicting the “strip assumption” highlight the need to consider the effects of three-dimensional turbulence (3D effect). This study develops an analysis model that considers the three-dimensionality of turbulence and derives a function containing the section-shape-dependent characteristic parameters to represent the 3D effect. A method for identifying the parameters through a wind tunnel test is proposed to solve this function. The parameters for the square cross section are then identified in two different turbulence fields, revealing that the identification parameters of both cases are nearly identical. This similarity indicates that the parameters are independent of the turbulence validating the proposed theories. Finally, the 3D effect on square cross-sectional structures with different aspect ratios under various turbulence integral scales is analyzed. The results showed that as the ratio of the turbulence integral scale to the windward width of the structures increases, the 3D effect reduces, but the rate of reduction slows down. In addition, increasing the aspect ratios of structures further mitigates the 3D effect, enhancing the accuracy of the “strip assumption.” These results can be a reference for evaluating the accuracy of the “strip assumption” theory for square cross-sectional high-rise buildings in atmospheric boundary layer turbulence. The proposed method can be applied to investigate the 3D effect on along-wind loads of slender structures with various cross-sectional shapes.

Formation of directed wide-aperture flows of runaway electrons in air-filled magnetized diodes.

This paper presents the results of research, development, and testing of magnetically insulated air diodes with replaceable graphite and stainless-steel tubular and coaxial cathodes of various configurations capable of generating directed bunches of runaway electrons. At the anode, the bunches have cross sections shaped as circles or rings with an outer diameter of 1-2cm. The durations of the bunches, which carry currents of a few to tens of amperes, range from tens of picoseconds to 100ps, and their charges range from tenths of a nanocoulomb to a few nanocoulombs. The kinetic energy of the bunch electrons at the peak of the current pulse is typically of the order of 150keV. The bunch parameters are set (and varied) by varying the amplitude and duration of the subnanosecond high-voltage pulse driving the diode; they depend on the cathode material and on the strength and profile of the applied external magnetic field. The bunches, retaining their cross-sectional structure, are brought out from the diode, along the field lines, through a thin foil or mesh anode into the open space with a quasi-uniform magnetic field between two Helmholtz coils. In this space, the samples to be irradiated with electrons, similarly to objects exposed to radiation in various experiments and technological applications, can be placed.

Improving the forecast accuracy of wind power by leveraging multiple hierarchical structure

Renewable energy generation is of utmost importance for global decarbonization. Forecasting renewable energies, particularly wind energy, is challenging due to the inherent uncertainty in wind energy generation, which depends on weather conditions. Recent advances in hierarchical forecasting through reconciliation have demonstrated a significant increase in the quality of wind energy forecasts for short-term periods. We leverage the cross-sectional and temporal hierarchical structure of turbines in wind farms and build cross-temporal hierarchies to further investigate how integrated cross-sectional and temporal dimensions can add value to forecast accuracy in wind farms. We found that cross-temporal reconciliation was superior to individual cross-sectional reconciliation at multiple temporal aggregations. Additionally, machine learning based forecasts that were cross-temporally reconciled demonstrated high accuracy at coarser temporal granularities, which may encourage adoption for short-term wind forecasts. Empirically, we provide insights for decision-makers on the best methods for forecasting high-frequency wind data across different forecasting horizons and levels.

The Performance and Fabrication of 3D Variable Cross-Section Channel for Passive Microfluidic Control.

Passive fluid control has mostly been used for valves, pumps, and mixers in microfluidic systems. The basic principle is to generate localized losses in special channel structures, such as branches, grooves, or spirals. The flow field in two-dimensional space can be easily calculated using the typical Stokes formula, but it is challenging in three-dimensional space. Moreover, the flow field with periodic variable cross-sections channeled of polyhedral units has been neglected in this research field due to previous limitations in manufacturing technology. With the continuous progress of 3D printing technology, the field of microfluidic devices ushered in a new era of manufacturing three-dimensional irregular channels. In this study, we present finite analysis results for a periodic nodular-like channel. The experiments involve variations in the Reynold number (Re), periodic frequency, and comparative analyses with conventional structures. The findings indicate that this variable 3D cross-section structure can readily achieve performance comparable to other passive fluid control methods in valve applications. A 3D model of the periodic tetrahedron channel was fabricated using 3D printing to validate these conclusions. This research has the potential to significantly enhance the performance of passive fluid control units that have long been constrained by manufacturing dimensions.

Research on Categorizing and Deriving Proportions of Hanoks for Planning and Designing Hanok Architecture

A Hanok is a representative wooden structure in Korea and is recognized for its environmentally friendly architecture. Since the 2010s, the demand for Hanoks has increased significantly, but new Hanoks tend to be built with only numerical changes to existing plans or only imitate the shape. This is due to the fact that architectural designers do not have systematic training in Hanoks, so they rely on carpenters with extensive experience in Hanok construction. As designers reconfigure Hanok’s floor plan space using existing drawings to accommodate modernization, the building’s form changes as spatial reduction and expansion occur. This change in form creates problems with the proportions of the elements that make up a Hanok, such as the roof being smaller than the body or the building being taller than the scale of the floor plan. A more significant issue is the lack of recognition of the proportion problem. Therefore, this study has a direct role in the systematic design and construction of Hanoks by deriving objective proportions of Hanoks. To increase the objectivity of the data, numerical data of floor plans, cross-sections, and front elevations of national heritage Hanoks with well-preserved traditional shapes were extracted and analyzed for patterns. Subsequently, similar forms were categorized, and ultimately, the plan, section, and elevation proportions were quantified. The results indicated that the plan was characterized by spatial expansion in the X-axis direction more than the Y-axis while maintaining rectangular proportions. The cross-sectional structure showed a change in height depending on the width of the plan, and it was found that the larger the width of the plan, the lower the height ratio of the cross-section. Of particular interest was the analysis of the ratio of exposed area in the elevation, divided into three areas: roof, Gongpo, and the frame, and the interaction between the roof and Gongpo was confirmed within 63.7% of the total exposed area ratio. This result suggests that the proportion of Hanoks exists despite the different scales, times, and locations of Hanoks. This study can serve as a reference for designers in the process of verifying and modifying design drawings, and it is significant in providing a method and direction for building a new dataset for Hanok design.

A new strategy for semi quantitative analysis of pore structure for lithium-ion battery electrodes

The Lithium ions diffusion dynamic, electrons transfer and the growth of the solid electrolyte interfaces are in close relation to the pore structure of the anodes. The widely used mercury intrusion porosimetry suffers from serious severe reaction with the copper and aluminum substrate, and unable to provide the pore structure evolution in the cross-section direction of the electrode. And the X-ray computed tomography faces limitations in identifying the carbon gel phase and is associated with high costs. Therefore, it is of substantial interest to directly investigate the cross-sectional pore structure from SEM morphologies. In this study, the using of resin protected polishing method to expose the cross-sectional structure is proposed to analyze the porosity evolution of the cross-sectional structure for lithium-ion battery anode. This method can clearly expose the cross-sectional structure of the electrode preventing the disturbance of the height fluctuation of the active particles. The influence of the coating processes on the pore structure is studied with the help of image J software and the machine leaning plug-in. The porosity changes of the electrode along with the coating depth are clearly elucidated. This method provides a convenient and efficient solution on the structure characterization of the electrode in Lithium-ion batteries.

Development of high hydrogen permselective membranes by using a vapor treatment method

Abstract In recent years, the depletion of energy resources and global warming have led to the promotion of new energy resources. Hydrogen is attracting attention as one of the energy sources for the carbon-neutral society by 2050. Membrane separation is a method for separating and purifying hydrogen. In this study, we focused on developing high hydrogen permselectivity of silica membranes. We investigated the conditions necessary for membrane production to obtain a thin, dense separation layer. The results exhibited that the hydrogen permeation selectivity was enhanced in the silica membrane through the utilization of a 2-step deposition technique, which involves the combination of alternative feed and counter-diffusion chemical vapor deposition (CVD). The H2 permeance achieved by the 2-step method is 1.4×10−6 [mol m−2 s−1 Pa−1], representing 1.4 times higher than that of counter-diffusion CVD. In addition, the permeance ratio, which represents hydrogen selectivity, was significantly enhanced with the 2-step method, with H2/C3H8 = 260, twice as high as with CVD. Elemental mapping analysis of the cross-sectional structure revealed a concentration gradient in the deposited silica within the intermediate layer. This indicates that the silica separation layer may become an asymmetric structure. The 2-step method is expected to yield a thinner dense layer, which could contribute to improved permeance of silica separation membranes by reducing permeation resistance.

Optimization Design and Analysis of Irregular Cross-Sectional Structure in Water Conducting Fibers

Optimization Design and Analysis of Irregular Cross-Sectional Structure in Water Conducting Fibers