Effect Of Shape Research Articles

Compaction and shear characteristics of recycled construction & demolition aggregates in subgrade: Exploring particle breakage and shape effects

Recycling construction and demolition (C&D) wastes into useable aggregates in subgrade applications offers significant sustainability benefits. However, the characteristics of recycled aggregates, including particle morphology, crushing strength, and shear behavior, differ substantially from natural aggregates. This paper presented an extensive experimental study on the compaction and mechanics performances of recycled concrete and brick aggregates, with a particular focus on the effects of particle breakage and shape characteristics. The compaction of recycled aggregate specimens comprising three structural types was evaluated using heavy Marshall compaction (HMC) and Superpave gyratory compaction (SGC). The compaction characteristics and particle breakage were examined, enabling a profound understanding of the compaction mechanisms associated with both methods. Furthermore, triaxial shear tests were performed to scrutinize the influences of particle shape, compaction degree, and confining pressure on shear characteristics. Results showed that after 80 gyratory rotations in SGC, the compaction degree of recycled aggregates aligned with the targeted results obtained from HMC. Changes in fractal dimension after compaction exhibited direct correlations with the two-dimensional shape distribution. Axial coefficient, fractal dimension and confining pressure most strongly influenced shear strength. In light of these insights, prediction models for shear strength parameters were proposed using multiple regression analysis. Overall, the study provides valuable insights into the relationships between aggregate morphology, compaction response, breakage behavior, and shear performance. These findings can facilitate optimized design and construction using recycled aggregates to advance sustainable infrastructure development.

Spent caustic treatment by electrocoagulation process: effect of electrode shape and spacing

Spent caustic treatment by electrocoagulation process: effect of electrode shape and spacing

Effect of Heat Source Shape on Temperature and Heat Diffusion in Continuous Grinding Based on FEM

Effect of Heat Source Shape on Temperature and Heat Diffusion in Continuous Grinding Based on FEM

Understanding the dynamics of microplastics transport in urban stormwater runoff: Implications for pollution control and management

The transport of microplastics (MPs) from urban environments to water resources via stormwater runoff poses significant concerns due to its adverse impacts on water safety and aquatic ecosystems. This study presents a modeling approach aimed at understanding the transport mechanisms of MPs in an urban residential setting, considering settling and buoyant MPs. To consider the effect of MP shapes, the settling velocity of various settling MPs in shapes of fibers, films, and fragments was calculated. Using an analogy of sediment transport, a Rouse number criterion was used to analyze the transport of MPs. For buoyant MPs, it was assumed that they transport as wash-load as soon as they float in the water and the travel time for them to reach the storm drain was determined. The calculation of settling velocity revealed the influence of shape on the settling velocity of MPs was particularly pronounced as the equivalent diameter of the MPs increased. The transport mechanism for the smallest settling MPs, irrespective of their shapes, density, and depth of flow, was wash-load. However, for larger MPs, the shape and size distribution of settling MPs, along with the depth of flow and slope significantly influenced their transport mechanisms compared to sediment particles. The influence of weathering on the MPs’ transport mechanisms depended on their sizes and shapes. The site-specific characteristics, including slope and surface friction, significantly influenced the velocity of stormwater runoff and, consequently, the extent of MP transport during rain events. Moreover, an evaluation of the transport mechanism of settling MPs was conducted using the reported field data on MP abundance in road dust collected from residential and traffic sites. This study underscores the complexity of MP transport dynamics and provides a foundation for developing targeted strategies to mitigate MP pollution in urban environments.

Substantial Warming of the Atlantic Ocean in CMIP6 Models

Abstract The storage of anthropogenic heat in oceans is geographically inhomogeneous, leading to differential warming rates among major ocean basins with notable regional climate impacts. Our analyses of observation-based datasets show that the average warming rate of 0–2000-m Atlantic Ocean since 1960 is nearly threefold stronger than that of the Indo-Pacific Oceans. This feature is robustly captured by historical simulations of phase 6 of Coupled Model Intercomparison Project (CMIP6) and is projected to persist into the future. In CMIP6 simulations, the ocean heat uptake through surface heat fluxes plays a central role in shaping the interbasin warming contrasts. In addition to the slowdown of the Atlantic meridional overturning circulation as stressed in some existing studies, alterations of atmospheric conditions under greenhouse warming are also essential for the increased surface heat flux into the North Atlantic. Specifically, the reduced anthropogenic aerosol concentration in the North Atlantic since the 1980s has been favorable for the enhanced Atlantic Ocean heat uptake in CMIP6 models. Another previously overlooked factor is the geographic shape of the Atlantic Ocean which is relatively wide in midlatitudes and narrow in low latitudes, in contrast to that of the Indo-Pacific Oceans. Combined with the poleward migration of atmospheric circulations, which leads to the meridional pattern of surface heat uptake with broadly enhanced heat uptake in midlatitude oceans due to reduced surface wind speed and cloud cover, the geographic shape effect renders a higher basin-average heat uptake in the Atlantic.

The effects of inner electrode shape on the performance of dielectric barrier discharge reactor for oxidative removal of NO and SO2

Seagoing vessels are responsible for more than 90% of global freight traffic, but meanwhile, emission pollutants (NO x and SO x ) of seagoing vessels also cause serious air pollution. Nonthermal plasma (NTP) combined with wet scrubbing technology is considered to be a promising technology. In order to improve the oxidation efficiency and energy efficiency of the NTP reactor, the screw and rod inner electrodes of dielectric barrier discharge (DBD) reactor were investigated. To analyze the mechanism, the optical emission spectra (OES) of NTP were measured and numerical calculation was applied. The experiment results show that the NO oxidation removal efficiency of screw electrode is lower than that of rod electrode. However, the SO2 removal efficiency of screw electrode is higher. According to the OES experiment and numerical calculation, the electric field intensity of the screw electrode surface is much higher than that of the rod electrode surface, and it is easier to generate N radicals to form NO. For the same energy density condition, the OH radical generation efficiency of the screw electrode reactor is similar to that of the rod electrode, but the gas temperature in the discharge gap is higher. Therefore, the SO2 oxidation efficiency of the thread electrode is higher. This study provides guidance for the optimization of oxidation efficiency and energy consumption of DBD reactor.

On the effects of struts diameter and shape on the European Space Agency deep space antenna directivity and first side lobe

On the effects of struts diameter and shape on the European Space Agency deep space antenna directivity and first side lobe

Tip shape effects on the axial-flow-induced vibration of a cantilever rod

The influence of tip shape on flow-induced vibration of a cantilever rod subjected to axial water flow is experimentally investigated, through optical tracking of the rod movement and mapping of the instantaneous flow field around the rod tip. The experimental setup consists of a vertical cantilever rod housed within a tube. The rod tip shapes considered in this study include a blunt tip and cones with height-to-diameter ratios of 0.5, 1, and 2. The experiments were conducted across a Reynolds number range between 20k to 100k in both clamped-free and free-clamped configurations, representing opposite flow directions. The rod tip motion was captured using fast video image tracking, whereas the flow field near the rod tip was obtained using particle image velocimetry (PIV). The rod vibration dynamics exhibited a primarily fuzzy period-1 behavior, characterized by a periodic motion with a chaotic component. Flutter-like oscillation and buckling were also observed at higher Reynolds numbers, depending on the flow direction. The mechanisms of fluid-structure interaction involved turbulent buffeting and movement-induced excitations. Unsteady flow separation around the rod tip was identified as a further contributing mechanism to flow excitation. In the clamped-free configuration, unsteady flow separation was more pronounced for the cone tips due to the increased rod surface area in the wake region, leading to larger vibration amplitude. In the free-clamped configuration, flow separation effects were more prominent for the blunt tip, as the streamlined cone shapes were less prone to flow separations. Overall, the rod with a blunt tip resulted in smaller displacement in the clamped-free configuration, while the rods with cone tips led to smaller displacement in the free-clamped configuration.

Blasting profile evaluation of sand-mud interbedded surrounding rock during the large-span tunnel construction

The sand-mud interbedded surrounding rock contains discontinuities, such as horizontal bedding, joints, weak planes and weak interlayers. Drilling and blasting construction in this kind of surrounding rock is very likely to cause very serious over-/under-excavation phenomenon and excessive damage to surrounding rock, and the contour flatness after smooth blasting of the tunnel is also difficult to be guaranteed, which increases subsequent construction procedures and reduces production efficiency. In order to effectively evaluate the smooth blasting effect of the sand-mud interbedded surrounding rock tunnel, taking a tunnel project in southwest China as the research background, the blasting numerical simulation of the sand-mud interbedded surrounding rock tunnel was carried out using the dynamic analysis program, and the corresponding blasting optimization scheme was obtained. Subsequently, based on fuzzy mathematical theory, the evaluation system of blasting effect of sand-mud interbedded tunnel was established by combining the evaluation criteria of tunnel smooth blasting quality. Immediately afterwards, the weights of each influencing factor index were determined, and the blasting shaping effect of the original blasting scheme and the optimized blasting scheme was evaluated. Finally, the results have shown that the optimized tunnel blasting profile effect was better than the original blasting scheme. The corresponding research results have certain guiding significance for similar tunnel blasting effect evaluation and blasting parameter design.

Effect of size and shape of artificial pellets on capture success for Octopus tetricus paralarvae

The culture of the paralarvae of merobenthic octopus species generally results in high mortalities with many attempts failing to rear the paralarvae through to juvenile stage. Progress has been made with higher survival for paralarvae cultures, but all successful paralarvae cultures rely heavily on decapod zoeae, which are labour intensive and costly to maintain in many instances. The development of an artificial pellet that is easily captured, can be rapidly consumed and fulfils the nutritional needs of octopus paralarvae would greatly advance octopus paralarvae culture. The aim of this study was to evaluate the effect of shape and size of artificial pellets on feeding behaviour for early Octopus tetricus paralarvae. This study tested the capture success of six different artificial pellets in a crossed experiment for size (i.e., small, medium and large), and shape (i.e., spherical or rectangular). Paralarvae were observed individually for up to 5 min with the number, size, shape and handling time of pellets captured by 2 days post-hatch O. tetricus paralarvae being recorded. A total of 105 out of 250 paralarvae captured one of the six artificial pellets with no difference between the two provided shapes for small and large pellets. In contrast, there was a strong preference for smaller artificial pellets with 57 out of 105 paralarvae capturing the small pellets. The handling times ranged from 1 to 485 s across all sizes and shapes of artificial pellets with shorter mean handling times for rectangular artificial pellets (mean of 13 ± 41 s) compared to spherical artificial pellets (mean of 31 ± 97 s), regardless of size. Overall, handling times were rather short (< 20 s) for the majority of (91%) of paralarvae that captured artificial pellets. The results show that pellet shape is mostly irrelevant to early O. tetricus paralarvae, but size is an important factor that must be considered. Moreover, the short handling times suggest a low palatability of the artificial pellets used in the current study, which will be addressed in future studies.

Understanding the shape effect on the structural, energetic, magnetic, and pressure properties of the 38 atom-Co-Fe-Pd nanoalloys using Gupta and DFT calculations

The alloy of magnetic metals with noble metals plays a key role in showing the magnetism of 3d metals and the catalytic properties of noble metals. A growing body of evidence suggests that 38 atoms is one of the most critical sizes for Ih and TO motifs. This study analyses the roles played by the shape effect on the structures, energies, magnetism, and pressures of Co6FenPd32-n (n = 0-32) nanoalloys and provides evidence regarding this phenomenon. Therefore, this study should be of value to researchers wishing to conduct future experimental and theoretical studies on the catalytic, electronic, optical, and magnetic properties of nanoalloys.

Effects of electrode shape in micro-electro-discharge patterning of carbon nanotube forests

This paper reports the performance of different tool electrode structures in micropatterning of vertically aligned carbon nanotube (CNT) forests through dry micro-electro-discharge machining (μEDM). Micro cylindrical electrodes of tungsten with flat and hemispherically rounded tips were employed in this study. The rounded-tip electrode was shaped using a custom wet μEDM process. Both types of electrodes were used to pattern arrays of micro test slots at different depths and discharge voltages on a multi-walled CNT forest from which the resultant discharge gaps were experimentally characterized. The rounded-tip electrode showed a 2.1–2.4× reduction in the discharge gap with applied voltages of 15–20 V, suggesting its potential to improve the lateral resolution of the patterning process when compared with the flat-tip case. Finite element analysis of the process configuration with these two electrodes was conducted and showed good agreement with the improvement factors of the discharge gap experimentally observed. However, the process using the rounded-tip electrode resulted in larger variations on the bottom surfaces of the created patterns, while the use of the flat-tip electrode provided higher uniformity on these surfaces, revealing an apparent trade-off relationship between the discharge gap and the patterning uniformity for the two electrode types under the tested conditions. Elemental analysis of the processed CNT forest surfaces showed no detectable contamination from the electrodes onto the forest structures patterned using either electrode.

Effect of Acoustic Enclosure on the Sound Transmission Loss of Multi-Layered Micro-Perforated Plates

This study presents an examination of the transmission properties of multilayered partitions made up of multiple micro-perforated plates (MPPs) coupled to acoustic enclosures with general impedance boundaries. Multi-layered MPPs can lower the transmission while minimizing reflection in the source and receiving enclosure. Previous research has mainly focused on the double MPPs or triple MPPs partition itself. However, it is vital to analyze the in-situ sound transmission loss of the multi-layered MPP and their efficiency in a complex vibro-acoustic environment. The case when the multilayered MPPs are coupled to a receiving enclosure or coupled to both a source and receiving enclosure is investigated. The objective is to provide an analytical method to evaluate the transmission properties of multilayered MPPs coupled to acoustic enclosures while being computationally more efficient than the finite element method (FEM). Using the modified Fourier series for the acoustic pressure, a variational form for the acoustic and structure medium yields a completely coupled vibroacoustic system. A comparison between the sound transmission loss of the double MPPs, when mounted on an impedance tube and coupled to acoustics enclosures, shows the modal effect of the enclosures. The effect of enclosure shape, impedance boundary, perforation ratio, air gap thickness on the sound transmission properties of the double MPPs structure is examined for both cases. Finally, in both situations, the performance of triple MPP structure insulation is evaluated.

Fast and accurate prediction of interference spectra of non-adiabatic tapered microfiber Mach-Zehnder interferometer in liquid

Microfiber Mach-Zehnder interferometer (MMZI) is a widely used optical device. To solve the problems of large difference between the theoretical and experimental spectrum, low calculation efficiency, poor universality in spectrum calculation of MMZI, a fast and accurate calculation method for predicting the interference spectrum of MMZI used in liquid is proposed. In calculations, phase accumulated in transition region of the taper is considered to reach a good agreement between theoretical and experimental spectrum. To further improve the computational efficiency, dependence of the phase accumulation on wavelength is developed by linear fitting, and a non-linear fitting of difference of effective refractive index (∆neff) on fiber diameter, wavelength, temperature and salinity of the surrounding is obtained by the data from commercial software. In addition, a visual interface for displaying the predicted spectrum is established, by which one accurate spectral calculation can be realized within only two or three seconds. Finally, effects of LP03 mode and shape of transition region on transmission spectrum are discussed and the accuracy of this method is also verified by sensitivity. The calculation method demonstrated here provides an accurate and fast spectral prediction method for MMZI, and will afford important reference for sensor design and optimization.

Mechanical anisotropy on reduced ballistic limit of phosphorene by cone wave reflection：A computational study

Two-dimensional materials, such as phosphorene, exhibit exceptional electrical and mechanical properties, offering promising prospects for both electronic and mechanical applications. To design more mechanically reliable devices using phosphorene, exploring its mechanical performance, especially impact resistance, is necessary. Here, coarse-grained molecular dynamics simulations are presented to study the mechanical responses of phosphorene under ballistic impact. Interestingly, size-dependent behaviors have been observed, which could be attributed to a coupling effect of cone wave reflection and membrane size. Owing to significant differences in Young’s modulus between the armchair and zigzag direction in phosphorene, mechanical wave propagation exhibits substantial anisotropy in a single-layer phosphorene membrane. A critical membrane size has been identified, below which cone wave reflections from the boundaries can induce perforation: a phenomenon particularly relevant to micro-ballistic testing of two-dimensional material membranes. The effect of boundary shape on reduction in ballistic limit has been studied, in which all the phosphorene sheets in the study are elliptical while the axial ratio of the ellipses is varied from 0.54 to 1.85. The axial ratio 0.69 is proven to maximize the strain amplification induced by cone wave reflection, thus leading to the biggest reduction in ballistic impact for phosphorene. A unitless indicator based on atomic Green-Lagrange strain has been proposed, which can effectively quantify the boundary shape effect on the reduced ballistic limit. Our findings provide timely guidance for the design of future nanodevices using phosphorene with high impact resistance.

Numerical Study on Aerodynamic Noise Reduction in Passenger Car with Fender Shape Optimization

Despite the rapid development of vehicle intelligent technology, the aerodynamic noise problem of internal combustion engine vehicles and pure electric vehicles at high speed has always been a growing problem. In this study, the effects of the car body fender shape on the aerodynamic noises of the rearview mirror and wheel region were investigated, and a noise reduction method was also proposed by optimizing the fender shape. To realize the parametric modeling of the fender, five positional variables were selected to define the fender configuration; the free-form deformation (FFD) method was used to establish the response fender model according the DOE schemes, and computational fluid dynamics (CFD) simulations are used to obtain the noise results. Then, with the help of the radial basis function (RBF) model and the adaptive simulated annealing (ASA) algorithm, the aerodynamic shape of the fender was optimized to reduce aerodynamic noise. Comparative analysis was then employed to assess flow field characteristics of the optimized model against the original model and elucidate the fender configuration’s contribution to aerodynamic noise reduction and its realization mechanism.

Axial compression performance of partially encased concrete columns with web opening

The objective of this study is to comprehensively assess the behavior of partially encased concrete (PEC) columns with web openings under axial compression. The primary objectives of this study are to analyze damage patterns and investigate the influence of key parameters, such as concrete strength, opening rate, and opening shape, on the ductility index and ultimate load-carrying capacity. The study employs experimental testing to examine the response of the PEC columns, with a particular focus on the mechanisms of concrete fracture and flange flexing. Notably, the study reveals a significant impact of the opening rate on the bearing capacity, while the effect of opening shape is comparatively minor. Furthermore, computational analyses are conducted to deepen the understanding of structural behavior. The study builds upon existing research to propose a novel method for calculating the bearing capacity of PEC columns with web openings. This method introduces two discount factors to enhance predictive accuracy.

Damped kink motions in a system of two solar coronal tubes with elliptic cross sections

Aims. This study is motivated by observations of coordinated transverse displacements in neighboring solar active region loops, addressing specifically how the behavior of kink motions in straight two-tube equilibria is impacted by tube interactions and tube cross-sectional shapes. Methods. We worked with linear, ideal, pressureless magnetohydrodynamics. Axially standing kink motions were examined as an initial value problem for transversely structured equilibria involving two identical, field-aligned, density-enhanced tubes with elliptic cross sections (elliptic tubes). Continuously nonuniform layers were implemented around both tube boundaries. We numerically followed the system response to external velocity drivers, largely focusing on the quasi-mode stage of internal flows to derive the pertinent periods and damping times. Results. The periods and damping times that we derive for two-circular-tube setups justify the available modal results found with the T-matrix approach. Regardless of cross-sectional shapes, our nonuniform layers feature the development of small-scale shears and energy accumulation around Alfvén resonances, indicative of resonant absorption and phase mixing. As with two-circular-tube systems, our configurational symmetries still make it possible to classify lower-order kink motions by the polarization and symmetric properties of the internal flows; hence, such motions are labeled as S​x and Ax. However, the periods and damping times for two-elliptic-tube setups further depend on cross-sectional aspect ratios, with Ax motions occasionally damped less rapidly than S​x motions. We find uncertainties up to ∼20% (∼50%) for the axial Alfvén time (the inhomogeneity lengthscale) if the periods (damping times) computed for two-elliptic-tube setups are seismologically inverted with canonical theories for isolated circular tubes. Conclusions. The effects of loop interactions and cross-sectional shapes need to be considered when the periods, and in particular the damping times, are seismologically exploited for coordinated transverse displacements in adjacent coronal loops.

Investigation on vibration characteristics of rock based on circular plate and cylinder model: dimension, geometric shape and boundary condition

Abstract The declaration on the “natural frequency of rock” exists in many engineering areas, and it has caused many misunderstandings. Different from the mass-spring model usually used, the circular plate model and cylinder model are respectively established to clarify the relationship between the vibration characteristics (including natural frequency and vibration mode) and their influencing factors of rock by modal analysis. The effect of dimension, geometric shape, and boundary condition on the vibration characteristics of rock with plate structure is investigated, in which the semi-analytical solutions agree well with the simulation results. By using the cylinder model based upon the Lamé-Navier Eq., the effect of such influencing factors on the vibration characteristics of the block rock sample is further studied and verified by numerical simulation and experimental results. The results suggest that the natural frequency of “rock” (including the experimental rock sample) is strongly dependent on the dimension, geometric shape, and boundary condition. The resonance frequency observed in the excitation experiment is not only closely associated with the natural frequency of a specific order, but also dependent on the dominance of the particular vibration mode. These findings contribute to a better understanding of the rock-breaking mechanism under dynamic loads with a certain excitation frequency.

Analysis of Fracture Damage Mechanical Properties of Particle Reinforced Polymer Composite Film Based on Micro-macro Finite Element Method

Abstract The particle reinforcement and related effect on fracture damage mechanical properties of polymers have been studied in this paper. Based on the uniaxial tensile test result of particle reinforced PVDF composites, the parameters of macro elastic-plastic finite element model and the micro particle reinforced model are obtained. The effects of boundary conditions, shape and size of damage notch on fracture damage mechanical properties of PVDF composites are studied from macroscopic view. The uniaxial tensile mechanical properties and elastic modulus are increased with notch angle. The damage analysis of the micro model shows that the reinforcement of composite is best when the content of SiO2 is 6%. Debonding between particles and matrix indicates have great effect on crack propagation. The micro-macro finite element model is effective tool to study the damage mechanical properties of particle reinforced polymers.&amp;#xD;