Effect Of Shape Research Articles

Renormalization group model of turbulent bioconvection of gyrotactic microorganisms

The problems connected with processes of turbulent bioconvection are considered. These processes are typical for technologies of microbiological and other industries. The concept of using renormalization groups in the theory of turbulence is shown. A step-by-step algorithm for applying the renormalization methodology to deriving the equation for mass transfer in bioconvective processes, which includes renormalization of the turbulent diffusion coefficient, is presented. The dependence for the turbulent Schmidt number was obtained. It has been shown that turbulent Schmidt number is function of six parameters: molecular Schmidt number, turbulent viscosity, molecular viscosity, parameter of geometric shape of microorganisms, average velocity of motion of microorganisms relative to the fluid, orientation parameter. The turbulent Schmidt number enables closing the diffusion equation. The effect of the geometric shape of microorganisms on the development of turbulence in a bioconvective flow in the presence of gyrotactic microorganisms is analyzed. Analysis shows that microorganisms with spherical symmetry make a small contribution to the formation of turbulent mass transfer processes. The results of the analysis are in a good agreement with data from studies of the nonlinear hydrodynamic stability of bioconvective processes based on the Lorentz model.

EXPERIMENTAL INVESTIGATIONS ON AEROELASTIC STABILITY OF COMBINED PLUNGE-PITCH MODE SHAPES IN A LINEAR COMPRESSOR CASCADE

Abstract The effect of mode shape and reduced frequency on the flutter stability of a linear low-speed compressor cascade was investigated experimentally, employing the aerodynamic influence coefficient (AIC) approach. This paper describes in detail the methodology, experimental setup, and measurement techniques. It presents experimentally determined influence coefficients, and discusses the findings with regards to the aeroelastic design parameter “plunge-to-twist incidence ratio” (PTIR), which combines reduced frequency and torsion axis setback in an attempt a design variable reduction. The influence of the vibrating blade on itself was always stabilizing, while other blades, mainly the first pressure side neighbour, vibrating at forward-travelling, low nodal diameter IPBAs, can destabilize the reference blade. As PTIR is increased, the phase of the complex modal force coefficients (AICs) of all blades is decreased, increasing the stabilizing effect of the vibrating blade on itself and overall cascade stability. Within the considered parameter range, the impact of reduced frequency is eliminated to a large extent if the incidence ratio is kept constant, requiring the torsion axis setback to be adjusted accordingly. The findings show that the plunge-to-twist incidence ratio is a meaningful aeroelastic design parameter that can explain the global effect of mode shape on flutter stability and should be considered early in the aeromechanical blade design process to ensure flutter-free blading.

Be careful of the sharp Edges! how and why circular versus angular shapes influence consumer adoption of new products

One of the key psychological barriers to consumer innovation adoption is the perceived learning costs associated with new products. This study proposes a novel product design strategy to increase consumer adoption of new products by reducing inferred learning costs through the design of product shapes. One field experiment and three lab experiments showed that circular (vs. angular) shapes of new products decreased perceived learning costs, which, in turn, enhanced consumer innovation adoption intentions. Furthermore, the positive effect of circular shapes is attenuated when external cues of reduced learning costs are present (vs. absent) and when the goal of seeking product capability (vs. ease of use) is salient.

Effect of shape and thermal conductivity of microstructured capillary-porous coatings on heat transfer during evaporation and boiling in thin horizontal liquid layers

Investigation results on heat transfer during evaporation and boiling in thin horizontal liquid layers on 2D modulated capillary-porous coatings with a sinusoidal profile in a wide range of relative pressures and layer heights are presented in this paper. Coatings were made on a 3D laser printer using the technology of additive selective laser sintering (SLS). One coating was made of bronze with a modulation wavelength equal to the Laplace constant of the working fluid and two coatings were made of stainless steel and bronze with a doubled wavelength. The experimental data obtained on the coatings were compared with each other and with the values obtained by evaporation and boiling of n-dodecane on a smooth surface under the same conditions. It is shown that in the region of low relative pressures in liquid layers with a height less than the Laplace constant, heat transfer intensification achieved on a sample made of a material with low thermal conductivity (stainless steel) was five times higher as compared to a smooth surface. In the range of relative pressures, when nucleate boiling was observed in the layers, the temperature difference reached on the bronze coatings was approximately 3–4 times less than on a smooth surface. The temperature difference for the stainless steel coating changed little with an increase in the heat flux. In pre-crisis conditions, the temperature difference during boiling on the stainless steel coating was less than on the bronze coatings in the entire range of relative pressures and layer heights. The highest critical heat fluxes were obtained on a bronze coating with a modulation wavelength equal to the Laplace constant.

Influence of Rolling Resistance and Particle Size Distribution in the Simulation of Sand Infiltration into the Static Gravel Bed

Fine sediment infiltration and subsequent clogging in a gravel bed affect several fluvial, ecological, and biological processes, resulting in the degradation of the river ecosystem. Despite many experimental and a few numerical studies, the process is yet to be entirely understood. We employed a pure Lagrangian framework, called the Discrete Element Method (DEM), to numerically investigate the infiltration process. Special attention is given to tackling the issue of non-spherical and irregular particle shapes and particle size distributions (PSDs) in numerical simulations. Due to computational limitations, these aspects were either not considered or simplified in previous numerical studies. We implicitly included non-spherical and irregular shape effects through rolling resistance models, which do not cause excessive computational overhead. Our study shows that rolling resistance models greatly influence packing and fine sediment infiltration. However, they may also lead to unphysical particle behavior; thus, they should be carefully used in numerical simulations. Oversimplified PSDs do not mirror natural systems, and full PSDs pose computational challenges. Sufficient grain classes are needed to mimic the non-homogeneity and poly-dispersity found in natural fluvial sediments. The infiltrating characteristics of sand concerning PSD and shape effects are linked to size ratio D15,Gravel/D85,Sand, assuring physical and realistic modeling of the infiltration process.

Single Living Cell "Observation-Analysis" Integrated Platform Decodes Cell Migration Plasticity Orchestrated by Nucleocytoplasmic STAT3.

Cell migration requires the interplay among diverse migration patterns. The molecular basis of distinct migration programs is undoubtedly vital but not fully explored. Meanwhile, the lack of tools for investigating spontaneous migratory plasticity in a single living cell also adds to the hindrance. Here, we developed a micro/nanotechnology-enabled single-cell analytical platform to achieve coherent monitoring of spontaneous migratory pattern and signaling molecules. Via the platform, we unveiled a previously unappreciated STAT3 regionalization on the multifunctional regulations of migration. Specifically, nuclear STAT3 is associated with amoeboid migration, while cytoplasmic STAT3 promotes mesenchymal movement. Opposing effects of JAK2 multisite phosphorylation shape its response to STAT3 distribution in a dynamic and antagonistic manner, eventually triggering a reversible amoeboid-mesenchymal transition. Based on the above results, bioinformatics further revealed a possible downstream regulator of nucleocytoplasmic STAT3. Thus, our platform, as an exciting technological advance in single-cell migration research, can provide in-depth mechanism interpretations of tumor metastasis and progression.

Hemodynamic evaluation of biomaterial-based surgery for Tetralogy of Fallot using a biorobotic heart, in silico, and ovine models.

Tetralogy of Fallot is a congenital heart disease affecting newborns and involves stenosis of the right ventricular outflow tract (RVOT). Surgical correction often widens the RVOT with a transannular enlargement patch, but this causes issues including pulmonary valve insufficiency and progressive right ventricle failure. A monocusp valve can prevent pulmonary regurgitation; however, valve failure resulting from factors including leaflet design, morphology, and immune response can occur, ultimately resulting in pulmonary insufficiency. A multimodal platform to quantitatively evaluate the effect of shape, size, and material on clinical outcomes could optimize monocusp design. This study introduces a benchtop soft biorobotic heart model, a computational fluid model of the RVOT, and a monocusp valve made from an entirely biological cell-assembled extracellular matrix (CAM) to tackle the multifaceted issue of monocusp failure. The hydrodynamic and mechanical performance of RVOT repair strategies was assessed in biorobotic and computational platforms. The monocusp valve design was validated in vivo in ovine models through echocardiography, cardiac magnetic resonance, and catheterization. These models supported assessment of surgical feasibility, handling, suturability, and hemodynamic and mechanical monocusp capabilities. The CAM-based monocusp offered a competent pulmonary valve with regurgitation of 4.6 ± 0.9% and a transvalvular pressure gradient of 4.3 ± 1.4 millimeters of mercury after 7 days of implantation in sheep. The biorobotic heart model, in silico analysis, and in vivo RVOT modeling allowed iteration in monocusp design not now feasible in a clinical environment and will support future surgical testing of biomaterials for complex congenital heart malformations.

The effect of taillight shapes and vehicle distance on rearward drivers’ hazard perception

Rear-end collisions are prevalent during night driving. Taillights are vital in conveying hazards between leading and following vehicles at night. Taillights highlight a vehicle’s presence, particularly for vehicles following from behind. Therefore, it is essential to design taillights that maximize the perception of hazards for drivers behind them. This study explored how different taillight shapes affect rear drivers’ hazard perceptions during nighttime driving. Two experiments were conducted using ERP measurements to study the effects of taillight shapes (three square types in Experiment 1: solid, array, and contour; two linear types in Experiment 2: through type and non-through type) and the distance to the leading vehicle on participants’ hazard perceptions. Participants responded to images of nighttime driving scenarios during the experiments while their ERP and behavioral data were recorded. The stimulus images showed the view from a driver looking at the vehicle ahead on a clear night. The neural process of hazard perception consists of two stages: automatic detection (early) and evaluation (later). In this study, P2 indicated attention bias to the stimulus during the detection stage, and LPP indicated the negative emotion triggered by the stimulus during the evaluation stage. Experiment 1 showed that solid-shaped taillights were perceived as more hazardous and processed faster than other square taillight shapes. Experiment 2 found that non-through-type and through-type linear taillights were perceived as more hazardous during the automatic detection and subjective evaluation stages, respectively. However, the behavioral data showed that through-type taillights were considered more hazardous and were associated with shorter response times. Thus, solid square taillights and through-type linear taillights can be optimal ergonomic solutions. These findings can serve as a reference for taillight designers, manufacturers, and potential car buyers regarding safety considerations.

Effect of ceria morphology on hydrogen production via methane steam reforming for membrane reformer

AbstractHydrogen is a potential energy carrier in comparison to conventional fuels due to its high energy content. Methane is an attractive source for ‘on‐site’ production of hydrogen by using membrane reformer due to its low cost. However, such reformers are not well studied and high temperature operation of steam methane reforming (SMR) makes the integration with membrane separation difficult. Further, the main product of SMR is CO and H2 in which CO has an inhibition effect on the membrane separation process. Therefore, it is vital to synthesize a low temperature and low CO selective catalyst for a suitable integration with membrane reformer. Nickel‐based catalyst is widely used for SMR due to its low cost and high catalytic activity. CeO2 is a favoured support as it mobilizes the lattice oxygen and reduces the coke formation and CO selectivity. Though several studies are reported on CeO2 based support, the effect of CeO2 surface morphology is not studied for SMR. In the current work, Ni/CeO2 of different shapes (nanocube and nanorod) are synthesized. The complete characterization of the support was performed. The effect of support shape, calcination temperature, and reduction temperature on SMR activity is found at different operating temperatures. For each condition conversion, CO, CO2 selectivity, and hydrogen yield are calculated. The results show the CeO2 morphology has a considerable effect on conversion, CO selectivity, and hydrogen yield. It is found that ceria nanocube calcined at 550°C provides better performance at high temperature.

Effect of ceria morphology on hydrogen production via methane steam reforming for membrane reformer

AbstractHydrogen is a potential energy carrier in comparison to conventional fuels due to its high energy content. Methane is an attractive source for ‘on‐site’ production of hydrogen by using membrane reformer due to its low cost. However, such reformers are not well studied and high temperature operation of steam methane reforming (SMR) makes the integration with membrane separation difficult. Further, the main product of SMR is CO and H2 in which CO has an inhibition effect on the membrane separation process. Therefore, it is vital to synthesize a low temperature and low CO selective catalyst for a suitable integration with membrane reformer. Nickel‐based catalyst is widely used for SMR due to its low cost and high catalytic activity. CeO2 is a favoured support as it mobilizes the lattice oxygen and reduces the coke formation and CO selectivity. Though several studies are reported on CeO2 based support, the effect of CeO2 surface morphology is not studied for SMR. In the current work, Ni/CeO2 of different shapes (nanocube and nanorod) are synthesized. The complete characterization of the support was performed. The effect of support shape, calcination temperature, and reduction temperature on SMR activity is found at different operating temperatures. For each condition conversion, CO, CO2 selectivity, and hydrogen yield are calculated. The results show the CeO2 morphology has a considerable effect on conversion, CO selectivity, and hydrogen yield. It is found that ceria nanocube calcined at 550°C provides better performance at high temperature.

Investigation of axial buckling behavior in composite laminates reinforced with S-glass fiber and epoxy featuring double cutouts

This research examines the impact of double cutouts on the critical buckling load of woven S-Glass/epoxy composite laminates. The study is divided into two parts: the first part involves comparisons, while the second part introduces numerical analyses. Initially, critical buckling loads of composite laminates without cutouts are determined using numerical and experimental methods. Subsequently, the results are compared to ensure consistency of critical load values obtained from the different methods. In the second part, the study investigates the effects of fiber angle, shape (square and circular), size, and position of cutouts in the composite plate using finite element analysis. The findings suggest that the shape and position of the cutout on the plate primarily influence the critical buckling load of the composite plates with circular cutouts, resulting in a relatively lower change in buckling load compared to square ones.

Strain‐dependent and host genotype–dependent priority effects in gut microbiome assembly affect host fitness in Daphnia

AbstractThe arrival order of species can strongly influence the early assembly of ecological communities. Such events, known as priority effects, are documented in various ecological settings, but remain understudied within the context of the gut microbiome. Given the fundamental link between the gut microbiome and host health, exploring the potential role of priority effects in shaping the assembly and development of microbial communities within the gut becomes imperative. Using the freshwater planktonic crustacean Daphnia magna as a model system, we manipulated the immigration order of three bacterial strain pairs in two germ‐free genotypes and quantified gut microbiome composition and host fitness at two time points, namely day 8 and day 12. Priority effects were observed; however, their presence, amplitude, and direction (suppressive or facilitative) were found to be contingent on the identity of bacterial strain and host genotype. These findings were accompanied by notable differences in Daphnia life history traits across inoculation order treatments, shedding light on the tangible consequences of priority effects triggered by the sequence of bacterial strain arrival in the gut environment, for host fitness. Our results thus highlight the complex nature of priority effects in gut community assembly, their strain/genotype specificity, and their potential impact on the host.

Strain‐dependent and host genotype–dependent priority effects in gut microbiome assembly affect host fitness in Daphnia

AbstractThe arrival order of species can strongly influence the early assembly of ecological communities. Such events, known as priority effects, are documented in various ecological settings, but remain understudied within the context of the gut microbiome. Given the fundamental link between the gut microbiome and host health, exploring the potential role of priority effects in shaping the assembly and development of microbial communities within the gut becomes imperative. Using the freshwater planktonic crustacean Daphnia magna as a model system, we manipulated the immigration order of three bacterial strain pairs in two germ‐free genotypes and quantified gut microbiome composition and host fitness at two time points, namely day 8 and day 12. Priority effects were observed; however, their presence, amplitude, and direction (suppressive or facilitative) were found to be contingent on the identity of bacterial strain and host genotype. These findings were accompanied by notable differences in Daphnia life history traits across inoculation order treatments, shedding light on the tangible consequences of priority effects triggered by the sequence of bacterial strain arrival in the gut environment, for host fitness. Our results thus highlight the complex nature of priority effects in gut community assembly, their strain/genotype specificity, and their potential impact on the host.

Effects Of The Nozzle Exit Section Shape On The Velocity Field And Heat Transfer Of Impinging Synthetic Jets

"The versatility and effectiveness of synthetic impinging jets for cooling applications have pushed the scientific community to optimize the design of such devices investigating the effects of all the relevant flow parameters, such as the stroke length, the Reynolds number and the shape of the driving wave. The current work focuses on the influence of different nozzle exit section shapes on the flow field evolution and heat transfer behavior of synthetic jet. In work presented herein, the actuator consists of a loudspeaker oscillating inside a cavity provided with a nozzle that has a circular entry section and a variable-shape exit section with a fixed hydraulic diameter (equal to 20 mm). The exit section shapes investigated in the current work are the circular, the triangular, the square and rectangular one with aspect ratio equal to 2. Simultaneous synchronized two component particle image velocimetry and infrared thermography measurements are performed. Consistent results are found both in terms of flow fields as well as Nusselt patterns: small nozzle-to-plate distances exhibit less spreading of the jet combined with a less spreaded, although more intense, Nu pattern. Smaller nozzle-to-plate distances also reveal the shape of the nozzle in the thermal pattern: this behavior can be seen for every nozzle, and it is associated with the presence of a Nu peak in correspondence of every corner of the shape, where the three-lobe footprint of the triangular nozzle exit section shape is clearly visible. Larger nozzle-to-plate distances are associated with a higher spreading in the jet and a lower vertical velocity in the vicinity of the impinged plate. "

Effects Of The Nozzle Exit Section Shape On The Velocity Field And Heat Transfer Of Impinging Synthetic Jets

Effects Of The Nozzle Exit Section Shape On The Velocity Field And Heat Transfer Of Impinging Synthetic Jets

Effect of generalized dimple shape on load-carrying capacity and leakage characteristics of laser surface textured dry gas seal

Abstract The effect of dimple shape on load-carrying capacity (LCC) and leakage characteristics of a laser surface textured dry gas seal (LGS-DGS) is investigated. A new formula is employed to describe the dimple boundaries, and a generalized geometric model of polygon dimple surface is established. The influence of the key geometrical parameters of polygon dimple on opening force and leakage rate is studied. The optimized geometries of generalized polygon dimple for the maximum opening force are obtained. Results show that an inclined quadrilateral dimple with multi rows in the radial direction presents the largest opening force. The opening forces of the two-sided and quadrilateral dimples with micron-scale are significantly better than that of millimeter apertures, while the opening forces of the triangular, pentagonal and hexagonal dimples with millimeter-scale are larger than that of the micron types. The shape profile parameters, directional parameters and radial dimple number of polygon dimples should be properly designed for excellent LCC and leakage characteristics.

Transient Dynamic Response of Generally Shaped Arches under Interval Uncertainties

This paper endeavors to investigate the characteristics of the transient dynamic response of a generally shaped arch when influenced by uncertain parameters while being subjected to specific external excitation. The equations of motion of the generally shaped arches are derived by the differential quadrature (DQ) method, and the deterministic dynamic responses are calculated using the Newmark-β method. By employing the Chebyshev inclusive function, an interval method based on a non-intrusive polynomial surrogate model is developed, and the uncertain dynamic responses are reckoned by enabling numerical simulations. The results of the proposed interval method are compared with those obtained from the scanning method for validation. The effects of various shapes and rise span ratios on the dynamic responses are investigated through a parametric study. The results suggest that the degree of fluctuation in the uncertain dynamic behavior is influenced by the type of parameter. Additionally, the responses of each shaped arch decrease with the increase in the rise span ratios, and with the same rise span ratio, the deterministic responses and corresponding uncertain responses are also affected by the shape of the arch, and they are considered to be at a minimum when the arch shape is parabolic. This study will enhance understanding of the dynamic properties of arches with uncertainties and provide some basis for the assessment and health monitoring of arch structures.

Numerical Optimization Analysis of Floating Ring Seal Performance Based on Surface Texture

Much research and practical experience have shown that the utilization of textures has an enhancing effect on the performance of dynamic seals and the dynamic pressure lubrication of gas bearings. In order to optimize the performance of floating ring seals, this study systematically analyzes the effects of different texture shapes and their parameters. The Reynolds equation of the gas is solved by the successive over-relaxation (SOR) iteration method. The pressure and thickness distributions of the seal gas film are solved to derive the floating force, end leakage, friction, and the ratio of buoyancy to leakage within the seal. The effects of various texture shapes, including square, 2:1 rectangle, triangle, hexagon, and circle, as well as their parameters, such as texture depth, angle, and area share, on the sealing performance are discussed. Results show that the texture can increase the air film buoyancy and reduce friction, but it also increases the leakage by a small amount. Square textures and rectangular textures are relatively effective. The deeper the depth of the texture within a certain range, the better the overall performance of the floating ring seal. As the texture area percentage increases, leakage tends to increase and friction tends to decrease. A fractal roughness model is developed, the effect of surface roughness on sealing performance is briefly discussed, and finally the effect of surface texture with roughness is analyzed. Some texture parameters that can significantly optimize the sealing performance are obtained. Rectangular textures with certain parameters enhance the buoyancy of the air film by 81.2%, which is the most significant enhancement effect. This rectangular texture reduces friction by 25.8% but increases leakage by 79.5%. The triangular textures increase buoyancy by 28.02% and leakage increases by only 10.08% when the rotation speed is 15,000 r/min. The results show that texture with appropriate roughness significantly optimizes the performance of the floating ring seal.

Effects of pulse shape on pitch sensitivity of cochlear implant users

Contemporary cochlear implants (CIs) use cathodic-leading symmetric biphasic (C-BP) pulses for electrical stimulation. It remains unclear whether asymmetric pulses emphasizing the anodic or cathodic phase may improve spectral and temporal coding with CIs. This study tested place- and temporal-pitch sensitivity with C-BP, anodic-centered triphasic (A-TP), and cathodic-centered triphasic (C-TP) pulse trains on apical, middle, and basal electrodes in 10 implanted ears. Virtual channel ranking (VCR) thresholds (for place-pitch sensitivity) were measured at both a low and a high pulse rate of 99 (Experiment 1) and 1000 (Experiment 2) pulses per second (pps), and amplitude modulation frequency ranking (AMFR) thresholds (for temporal-pitch sensitivity) were measured at a 1000-pps pulse rate in Experiment 3. All stimuli were presented in monopolar mode. Results of all experiments showed that detection thresholds, most comfortable levels (MCLs), VCR thresholds, and AMFR thresholds were higher on more basal electrodes. C-BP pulses had longer active phase duration and thus lower detection thresholds and MCLs than A-TP and C-TP pulses. Compared to C-TP pulses, A-TP pulses had lower detection thresholds at the 99-pps but not the 1000-pps pulse rate, and had lower MCLs at both pulse rates. A-TP pulses led to lower VCR thresholds than C-BP pulses, and in turn than C-TP pulses, at the 1000-pps pulse rate. However, pulse shape did not affect VCR thresholds at the 99-pps pulse rate (possibly due to the fixed temporal pitch) or AMFR thresholds at the 1000-pps pulse rate (where the overall high performance may have reduced the changes with different pulse shapes). Notably, stronger polarity effect on VCR thresholds (or more improvement in VCR with A-TP than with C-TP pulses) at the 1000-pps pulse rate was associated with stronger polarity effect on detection thresholds at the 99-pps pulse rate (consistent with more degeneration of auditory nerve peripheral processes). The results suggest that A-TP pulses may improve place-pitch sensitivity or spectral coding for CI users, especially in situations with peripheral process degeneration.

Application of Multivariate Tromp Functions for Evaluating the Joint Impact of Particle Size, Shape and Wettability on the Separation of Ultrafine Particles via Flotation

Froth flotation predominantly separates particles according to their differences in wettability. However, other particle properties such as size, shape or density significantly influence the separation outcome as well. Froth flotation is most efficient for particles within a size range of about 20–200 μm, but challenges arise for very fine or coarse particles that are accompanied by low recoveries and poor selectivity. While the impact of particle size on the separation behavior in flotation is well known by now, the effect of particle shape is less studied and varies based on the investigated zone (suspension or froth) and separation apparatus used. Beyond these complexities, many particle properties are correlated, making it challenging to analyze the isolated impact of individual properties on the separation behavior. Therefore, a multidimensional perspective on the separation process, considering multiple particle properties, enhances the understanding of their collective influence. In this paper, the two-dimensional case is studied; i.e., a parametric modeling approach is applied to determine bivariate Tromp functions from scanning electron microscopy-based image data of the feed and the separated fractions. With these functions it is possible to characterize the separation behavior of particle systems. Using a model system of ultrafine (<10 μm) particles, consisting of either glass spheres or glass fragments with different wettability states as the floatable fraction and magnetite as the non-floatable fraction, allows for the investigation of the influence of descriptor vectors consisting of size, shape and wettability, on the separation. In this way, the present paper contributes to a better understanding of the complex interplay between certain descriptor vectors for the case of ultrafine particles. Furthermore, it demonstrates the benefits of using multivariate Tromp functions for evaluating separation processes and points out the limitations of SEM-based image measurements by means of mineral liberation analysis (MLA) for the studied particle size fraction.