High Shape Factor Research Articles

The process of saving cold energy in presence of nanomaterial within storage enclosure

Current work explores the potential benefits of incorporating nano-powders into water to enhance the freezing process, focusing on a tank equipped with fins for cold storage. By blending alumina nanoparticles with water, a nanomaterial is created, facilitating improved cold energy absorption through conduction mechanisms. The simplified mathematical model utilized in this study accounts for the dominance of conduction over convection, streamlining the equations for solution via the Galerkin method. Verification of the numerical techniques and assumptions against existing literature ensures the reliability of the model. The outputs illustrated a substantial decrement in completion time, with a 10.64 % decrease observed with an increase in shape factor. The most efficient freezing process occurs in the presence of nanoparticles with the highest shape factor and concentration. In comparison, the freezing time for water alone stands at 5033.7 s, marking a notable 32.7 % decrease with the introduction of nanoparticles.

A Dynamic Permeability Model in Shale Matrix after Hydraulic Fracturing: Considering Mineral and Pore Size Distribution, Dynamic Gas Entrapment and Variation in Poromechanics

Traditional research on apparent permeability in shale reservoirs has mainly focussed on effects such as poromechanics and porosity-assisted adsorption layers. However, for a more realistic representation of field conditions, a comprehensive multi-scale and multi-flowing mechanism model, considering the fracturing process, has not been thoroughly explored. To address this research gap, this study introduces an innovative workflow for dynamic permeability assessment. Initially, an accurate description of the pore size distribution (PSD) within three major mineral types in shale is developed using focussed ion beam-scanning electron microscopy (FIB-SEM) and nuclear magnetic resonance (NMR) data. Subsequently, an apparent permeability model is established by combining the PSD data, leading to the derivation of dynamic permeability. Finally, the PSD-related dynamic permeability model is refined by incorporating the effects of imbibition resulting from the fracturing process preceding shale gas production. The developed dynamic permeability model varies with pore and fracture pressures in the shale reservoir. The fracturing process induces water blockage, water-film formation, and water-bridging phenomena in shale, requiring additional pressure inputs to counteract capillary effects in hydrophilic minerals in shale, But also increases the overall permeability from increasing permeability at larger scale pores. Unlike traditional reservoirs, the production process commences when the fracture is depleted to 1–2 MPa exceeds the pore pressure, facilitated by the high concentration of hydrophobic organic matter pores in shale, this phenomenon explains the gas production at the intial production stage. The reduction in adsorption-layer thickness resulting from fracturing impacts permeability on a nano-scale by diminishing surface diffusion and the corresponding slip flow of gas. this phenomenon increases viscous-flow permeability from enlarged flow spacing, but the increased viscous flow does not fully offset the reduction caused by adsorbed-gas diffusion and slip flow. In addition to the phenomena arising from various field conditions, PSD in shale emerges as a crucial factor in determining dynamic permeability. Furthermore, considering the same PSD in shale, under identical pore spacing, the shape factor of slit-like clay minerals significantly influences overall permeability characteristics, much more slit-shaped pores(higher shape factor) reduce the overall permeability. The dynamic permeability-assisted embedded discrete fracture model (EDFM) showed higher accuracy in predicting shale gas production compared to the original model.

On the need to go beyond bucket modelling to evaluate NBS risk of failure under urban constraints

The need to combine simple analytical solutions to control the full spectrum of stochastic events, not just extreme rainfall events related to flood risk, in order to restore the natural water cycle has led to the adoption of probability analysis (PA) as a powerful design tool for urban drainage systems. Applications of PA to sustainable urban drainage and nature-based solution (NBS) design are numerous but often rely on a bucket modelling (BM) approach to assess the efficiency of retention and detention structures.Managing urban growth and climate change requires careful attention to 1) the shape of NBSs to fit into an existing urban grid and 2) the intensity of rainfall, which is expected to increase significantly. The BM approach is insensitive to the shape of technical solutions and the variability of rainfall intensity, so the PA was revised, coupled with a hydrodynamic modelling (HM) approach and compared with previous BM-based approaches.In the low-intensity rainfall regime, HM and BM predict completely different infiltration system (IS) overflow probabilities. In the high-intensity precipitation regime, both provide a bell-shaped probability density function of overflow volumes, although BM tends to underestimate IS overflow volumes with low shape factor and overestimate IS overflow volumes with high shape factor.

Slurry preparation for semi-solid metal direct writing by a novel approach of mixed powder remelting

Extrusion-based metal direct writing is a promising metal additive manufacturing technology due to its high efficiency and low cost. However, fabricating parts with high integrity and complex geometry remains challenging. The most critical factor is the unavailable of semi-solid slurries with uniform and nearly spherical solid particles, resulting in uncontrollable extrusion and printing. Currently, mixed powder remelting (MPR) is reported to preset the features of the solid phases, including volume fraction, morphology, and size distribution. Specifically, the semi-solid slurries of hypoeutectic AlSi alloys were obtained by preheating and shearing the mixed powder composed of eutectic AlSi alloy powder and pure aluminum powder. Their microstructural characteristics and rheological behavior were investigated, demonstrating the microstructure tailoring (controllable solid fraction and size distribution, high shape factor of about 0.9) and the reduced viscosity fluctuation by a factor of 7 compared with traditional processes. MPR shows unparalleled advantages for further engineering applications of metal direct writing.

Numerical unsteady modeling for solidification of PCM containing nanomaterials with thermal effect

Conservation and storage of energy are important issues for human beings in the 21st century. A significant part of the energy is consumed for space cooling in buildings during summer. Passive cooling systems are used due to their low-power consumption; they, however, have some limitations such as lack of sufficient low temperature for the storage of coolth, in various localities. These problems make passive cooling technologies suitable in limited regions and scenarios. In this work, the inclusions of nanomaterials were examined to accelerate the freezing of phase changing material (PCM), with the applications of fins. The base (PCM) is water and CuO nanoparticles were used in this investigation to upgrade the performance. KKL is used to estimate the properties of CuO–water nanofluids. The finite element method (FEM) was employed to simulate this unsteady process. The outcomes indicate that incorporating CuO nanoparticles into pure PCM speeds up solidification process. The total energy and average temperature profiles decrease as the number of undulations upsurges, while the solid fraction profile rises. Furthermore, for [Formula: see text][Formula: see text]nm, the uppermost rate of solidification is acquired. Increasing the concentration of CuO can make the freezing time to decrease by about 10.11% and 12.85% when the utilized shape factors are 3 and 5.7, respectively. Using particles with a higher shape factor causes the period to decrease by about 4% and 6.9% when concentration is 0.02 and 0.04, respectively.

Numerical thermal performance analysis of light steel insulated walls under fire

Light-gauge steel-framed (LSF) walls are being adopted by the Algerian construction industry as a new alternative to the traditional infilled frames due to the advantages they provide. The strength-to-weight ratio of Cold Formed Section (CFS) leads to lighter structures and a decrease in the building cost. However, in the case of fire, the high shape factor combined with the loss of material properties of the unprotected, slender CFS can result in structural failure. Because of their conductivity, elevated temperatures have an effect on the thermal performance of panels, necessitating the use of appropriate insulation. The purpose of this paper is to perform a numerical analysis of the thermal behavior of LSF walls protected by plasterboard or magnesium oxide board, as well as cavity insulations. Numerical models are developed, using ANSYS software to simulate the thermal performance of LSF walls under ISO 834 fire. Thermal simulations are done to predict temperature profiles, maximum temperatures, and the estimated fire resistance level (FRL). This research has produced results to better evaluate the influence of different systems of protection and insulation used for the CFS under fire.

Hybrid rubber‐concrete isolation slab system with various shape factors for structures subjected to horizontal and vertical vibrations

SummaryThe present framework proposed the development of a Hybrid Rubber‐Concrete Isolation Slab System (HRCISS) to support building structures subjected to horizontal and vertical vibration due to ground motion and machine or equipment operation in the structure. Given that the effect of the shape factor on both horizontal and vertical stiffness has yet to be reported, the proposed composite system was comprised of two layers under the nodal points of the upper layer near the slab corners with four High Damping Rubber (HDR) components positioned between the slab layers to dissipate multidirectional (horizontal and vertical directions) vibrations. The ABAQUS software was utilized to model the finite element model (FEM) and simulate the HRCISS subjected to cyclic horizontal and vertical displacements. For the optimal HDR design, the model was applied in five 3‐story buildings, and the effect of distinct shape factors (0 S 2) of the HDR bearings—the ratio of bearing's loaded area to unloaded area (free to bulge)—within the hybrid system was evaluated. For each building with a specific HDR shape factor, the HRCISS was installed in the first, second, and third stories, separately, to investigate the influence of the installation level of the isolation system on the overall structural performance. The multistory buildings were subjected to two types of vibration loads: the interior machine‐induced vibrations, and the exterior seismic‐induced vibrations in the horizontal and vertical directions. Based on the results, the FEM results proved the significant influence of the shape factors on the dynamic response of the HRCISS under both interior and exterior 3D vibrations when applied in multistory buildings. The lateral drift of the three‐story one‐bay buildings decreased with the decrement of shape factor with buildings of HRCISS installed in 1st story recording more reduction. Moreover, the deflection in the structural slab under the HRCISS decreased for lower shape factor bearings. Nevertheless, the reduced deflection was less affected by the level of the machine‐equipped story. The rubber layer also stiffened in shear and compression directions with a higher shape factor.

The Effect of Inlet Conditions on Turbine Endwall Loss

Abstract There can be significant variation and uncertainty in the flow conditions entering a blade row. This article explores how this variability can affect endwall loss in axial turbines. A computational study of three cascades with collinear inlet boundary layers is conducted. Endwall loss varies by more than a factor of 3 depending on the inlet conditions. This variation is caused by dissipation of secondary kinetic energy (SKE). The results can be understood by observing that the inlet conditions predominantly control how secondary vorticity is distributed within the blade passage. Modestly thick inlet boundary layers with high shape factor tend to displace vorticity toward the center of the passage. This displacement reduces vorticity cancellation, increasing secondary velocities, and SKE. A general method is formulated to estimate SKE in preliminary design. Optimum aspect ratio is shown to depend on the inlet boundary condition. Strategies to reduce endwall loss and minimize sensitivity to inlet conditions are then highlighted.

High stress corrosion cracking resistance of in-situ nanoparticle strengthened steel

Stress corrosion cracking (SCC) is extremely detrimental to the long-term applications of high-strength low-alloy steels. In this work, the critical effects of the dimension and morphology of the non-metallic inclusions on the SCC susceptibility and pitting corrosion were investigated. With the trace-element regional supply method, the inclusions are transformed from the detrimental sharp-edged (Ti, V)N and enormous MnS into globular or elliptical Al2O3 and multicomponent inclusions with small dimensions (3.41 ± 2.36 μm) and high equivalent shape factor (0.93 ± 0.02) in the in-situ nanoparticles strengthened steel. As a result, the corrosion current, depth and diameter of pits, and roughness of the surface were reduced with suppression of pitting corrosion. The superior SCC resistance in the in-situ nanoparticles strengthened steel was obtained by inclusion refinement. The strategy of inclusion refinement by in-situ nanoparticles is beneficial for designing SCC resistant steels.

RETRACTED ARTICLE: Solar radiation impact on ferrofluid convection with applying electric field

For estimating impact of electric force on treatment of ferrofluid, new numerical techniques have been involved in current article. The operate fluid contains iron oxide as additive in nano-sized with various shapes. The fraction of particles with nano-sized is smaller than 0.06, and for involving such effect, properties of carrier fluid have been changed based on empirical formulation with neglecting the slip velocity. There were two moving wall at the left and bottom surfaces which has highest temperature and voltage. The domain was porous and related terms were added in momentum according to non-Darcy assumption. Combined method of FVM and FEM was selected to find the solution for this problem. As electric force applied, the nanofluid can move with higher speed and two primary vortex convert to one stronger vortex. Nu augments about 125.52% and 65.43% with rise of voltage when Da = 1e2 and 1e5. Utilizing media with higher permeability lead to stronger collision with wall and Nu elevates about 113.29%. Replacing nanoparticle with higher shape factor instead of sphere, Nu augments about 3.69%.

LOCAL THERMAL NONEQUILIBRIUM VISCOUS DISSIPATIVE COUETTE FLOW IN A POROUS MEDIUM

A local thermal nonequilibrium Couette flow in a saturated porous medium, subjected to uniform heat flux, is investigated, where concern is focused on the effects of viscous dissipation. The temperature field is derived analytically in terms of Brinkman number (Br) and porous medium shape factor applied to conditions where the local thermal nonequilibrium effect is profound. Contrary to pressure-driven flow in porous medium, viscous dissipation has a more significant effect on the transverse temperature variation of a porous medium with high porous medium shape factor due to the shearing force on the moving wall. A comparison with the local thermal equilibrium model reveals that such an effect is heightened as the thermal resistance to heat conduction in fluid at the heated boundary becomes greater. The computed Nusselt number (Nu) indicates a reversal in the trend of declining Nu with increasing Br as the porous medium shape factor drops below one. As Br is a function of characteristic gap size, this study also gauges the effect of characteristic length scale of the parallel channel on the temperature field. The resulting fluid and solid temperature fields depend strongly on the characteristic gap size between parallel plates, while viscous dissipation intensification overrides the convection enhancement effect in microscale applications.

On-Chip All-Optical Tunable Filter With High Tuning Efficiency

We propose and realize a bandwidth and wavelength-tunable all-optical filter with high tuning efficiency based on double opto-mechanical microring resonators (MRRs) assisted Mach-Zehnder interferometer (MZI) structure, which is beneficial to achieve high extinction ratio and shape factor. As the optical field gradient is largely enhanced in the free-hanging MRRs, the opto-mechanical effect could be excited by low power consumption. By injecting the corresponding low resonance powers, the drop transmission of each MRR could be flexibly tuned based on the opto-mechanical effect. Consequently, the synthetic transmission of the microring-assisted MZI could be efficiently manipulated. The results show that by injecting pump powers of 0.40 mW and 1.84 mW, the bandwidth and wavelength of the all-optical filter could be tuned from 0.17 nm to 0.30 nm, and from 1550.09 nm to 1550.60 nm respectively with maintaining a high extinction ratio of 38 dB and a small passband ripple of 1 dB. Especially, the tuning efficiencies of bandwidth and wavelength could realize up to 0.325 nm/mW and 0.277 nm/mW, respectively. The proposed optical filter has dominant advantages of high tuning efficiencies and extinction ratios, small passband ripple and compact footprint, which has significant applications in on-chip all-optical systems.

Broadband optical single sideband generation using an ultra high shape-factor self coupled ring resonator

In this study, we realize an integrated generation of optical Single SideBand with Carrier (SSB+C) signal for microwave photonics applications. It has been achieved using a Micro Ring Modulator (MRM) combined with a cavity based wavelength selective filter. MRM, when applied with an RF input, results in a Double SideBand with Carrier (DSB+C) signal where one sideband is suppressed by applying this signal to the filter. The filter has been created using a single resonance-split self-coupled cavity with an extremely high shape factor of 0.69. The sideband suppression ratio between DSB+C and SSB+C ranges from 16 dB to 55 dB for a frequency range of 4 GHz to 20 GHz. Tunable suppression ratio of 21 dB has been achieved at a fixed frequency of 15 GHz. Dynamic range performance of the generated signal has been evaluated at a noise floor of -156 dBm. The dynamic range remains stable in the range of 1 GHz - 5 GHz at ∼ 80 dB.Hz2∕3.

Investigation on the genesis of the shape deformation of plates in New Plate mill, Rourkela Steel Plant

New Plate Mill (NPM), a state of the art facility has been commissioned at Rourkela Steel Plant (RSP). Facilities like roll bending, roll shifting and plan view rolling are integral part of the mill. High pressure de-scaling, accelerated cooling control (ACC) with high capacity hot plate leveller (HPL) & cold plate leveller (CPL) are other process facilities of the NPM. A special feature of the NPM (New Plate Mill) is its high roll separating force of 90MN. This enables high shape factor rolling that leads to the rolling of metallurgically sound thicker steel plate. Therefore it is possible to apply modern thermo-mechanically processing routes for the development of tailor made properties like high strength, toughness, close dimensional tolerance and excellent surface finish in plate.Trials were carried out for the achieving target mechanical properties with leaner chemistry by thermo-mechanical control processing (TMCP). After rolling, plates are passed through the Accelerated Cooling Control (ACC) unit for achieving desired mechanical properties. After ACC, waviness is visible in the plates and hence HPL is used for flattened the plate profile. Plates get flattened after hot plate leveling but after several minutes some waviness again occurs in the plates on the cooling bed. Initially several factors were considered for possible reason and thermal images of the plates were taken for understanding thermal variations in the plates. Finally, improper descaling and temperature inhomogeneity was found major factors affecting plates shape.

Compressive behavior of low shape factor lead-rubber bearings: Full-scale testing and numerical modeling

Low shape factor lead-rubber bearings, defined as bearings with relatively thick rubber layers, have been confirmed by several studies to be feasible for vertical seismic isolation because of their flexibility in the vertical direction. However, information on various behavior aspects of low shape factor lead-rubber bearings remains inadequate. With much greater vertical deformation under working conditions than conventional high or medium shape factor bearings, low shape factor lead-rubber bearings display certain unique mechanical behaviors due to the nonlinearity and inelasticity of lead plugs. The applicability of existing design equations to the compressive stiffness of low shape factor bearings remains unknown. Although it has been demonstrated that the axial load has an insignificant effect on the compressive stiffness of lead-rubber bearings with high or medium shape factors, few studies have referred to the influence of the axial load on the vertical stiffness of low shape factor bearings. To investigate the unique compressive behavior of the low shape factor lead-rubber bearings, bearings with various shape factors were tested under various axial loads to compare their compressive behavior in terms of compressive stiffness and force-displacement relationships. The obtained results indicate that the existing design formula for compressive stiffness is not applicable for lead-rubber bearings with a shape factor lower than 11. Although the axial load has a minor influence on the compressive stiffness of lead-rubber bearings with high shape factors, it has a non-negligible influence on that of low shape factor bearings. In addition, a unique behavior characterized by hardening in compressive stiffness is found in the force-displacement relationships of the bearings. Numerical models were developed and calibrated with the experimental results. A parametric study of the numerical models shows that the hardening phenomenon is caused by sliding between the lead-steel interfaces and the lead-rubber interfaces. This sliding decreases the vertical stiffness and reduces the energy dissipation of the bearings. An increase in the coefficient of friction between the interfaces can increase the compressive stiffness of bearings with relatively high shape factors, but bearings with low shape factors are insensitive to the friction coefficients.

Analysis of the 355 Aluminium Alloy Microstructure for Application in Thixoforming

The 355 aluminium alloy is known to have excellent thermodynamic characteristics that render it suitable as a raw material for rheocasting and thixoforming. However, besides the controllable transition from solid to liquid phase, the refined microstructure required in the semisolid range is one of the key factors with a strong influence on the rheology of the material. This paper intends to analyse the in situ behaviour of the microstructure, in terms of morphological change, using high-temperature laser scanning confocal microscopy. The 355 alloy was prepared via conventional casting, and refined with a 30-s exposition via ultrasonic melt treatment (UST - 20 Hz, 2 kW). The material was reheated up to the thixoforming target temperature of 595 °C at which it was maintained for 0, 30, 60, 90, and 120 s, after which all the samples were cooled in water. The samples subjected to UST prior to the heat treatment were more refined in terms of microstructural evolution; they exhibited reduction in grain size (~107 ± 16 μm), smallest primary phase particle size (~81 ± 7 μm), and high circularity shape factor (~0.59 ± 0.19 μm). In situ observation methods were employed to analyse evolution mechanisms such as Ostwald ripening and coalescence.

SIMA Processing of Cu34wt.%Zn2wt.%Pb Brass Alloy

Effects of SIMA processing on size and shape of primary solid particles of Cu34wt.%Zn2wt.%Pb brass alloy was investigated. The optimal temperature for semisolid processing of the alloy was found to be around 890 °C using Thermo-calc simulation software. Liquid fraction sensitivity of the alloy around this temperature is 0.012. The results indicated the formation of non-dendritic microstructure even after 1 min holding of 10% cold worked sample at 890 °C. Sphericity of the primary solid particles increased by increasing the cold working ratio and holding time. The smallest size (103 μm) and highest shape factor (0.84) of the primary solid particles were achieved at 30% cold working ratio and 5 min holding time.

A Semianalytical Approach for Nonlinear Dynamic System of Shallow Arches Using Higher Order Multistep Taylor Method

This study aimed at obtaining a semianalytical solution for nonlinear dynamic system of shallow arches. Taylor method was applied to find the analytical solution, and an investigation of their dynamic characteristic was carried out to verify the applicability of this methodology for the shallow arches under step or periodic excitation. A polynomial solution can be obtained from this multistep approach with respect to time, and direct buckling as well as indirect buckling of the shallow arches can be observed, also. The results indicated that the dynamic buckling load level was higher with higher shape factor. Additionally, a change of attractor in phase space was investigated. Coupling in symmetric mode as well as asymmetric mode was observed in case of indirect buckling, and a sensitive response was also manifested during sinusoidal and beating excitation. These results of applying multistep Taylor series for the investigation of displacement response and attractor change revealed that this analytical approach was valid in explaining the dynamic buckling behavior of shallow arches under direct and indirect snapping.

Investigation of adsorption isotherms and rotational speeds for low temperature regeneration of desiccant wheel systems

Effects of adsorption isotherms, namely shape factor and maximum adsorption capacity, and rotational speed on regeneration temperature of desiccant wheel systems are investigated. Higher maximum adsorption capacity is beneficial for reducing regeneration temperature especially for deep dehumidification of single-stage systems under humid climate, while the influence is not obvious with small dehumidification capacity. Higher shape factor (=1) is recommended for dehumidification at high relative humidity, while lower shape factor is better for low relative humidity. Rotational speed in the range of 10–15 r h−1 is advised for single and two-stage systems under a wide range of working conditions for both deep and regular dehumidification applications when wheel thickness is 0.2 m and maximum adsorption capacity is 0.8 kg kg−1. The reasons for different requirements of shape factor for regular and deep applications are discussed theoretically. Rotational speed ranges for different wheel thickness and maximum adsorption capacity are recommended.

Soft wheat quality characteristics required for making baking powder biscuits

Fifteen soft wheat varieties were evaluated for their grain, milling, flour and dough mixing characteristics, as well as their solvent retention capacities (SRCs), pasting properties and suitability for making baking powder biscuits, to identify wheat quality characteristics required for making biscuits. Grain and flour protein contents and sodium dodecyl sulfate sedimentation (SDSS) volume showed positive relationships with biscuit height and shape factor (SF). Kernel hardness, damaged starch content and water SRC exhibited negative correlations with biscuit specific volume (SV), while peak viscosity and grain protein content were positively associated with biscuit SV. Stepwise multiple regression analysis indicated that biscuit height and SV can be predicted from flour protein content (R2 = 0.65) and damaged starch content (R2 = 0.69), respectively; while SDSS volume and flour yield together predict biscuit SF (R2 = 0.83). Cluster analysis based on biscuit height and SF indicated that seven soft wheat varieties with flour protein contents greater than 7.9% and SDSS volumes lower than 32.0 mL produce good-quality biscuits with high height, intermediate SF, great SV and soft crumb. The results of this study suggest that soft wheat flours with intermediate-to-high protein contents (7.9–9.7%), intermediate SDSS volumes (20.0–32.0 mL) and low damaged starch contents (1.9–3.4%) are suitable for making desirable-quality biscuits.