bluuebunny/crossref_metadata_2025 huggingface dataset:
The feasibility of a Swiss complex interprofessional intervention to improve the management of procedural pain in neonates in the Finnish context: A qualitative study
Authors: Mäki‐Asiala Mariaana , Balice‐Bourgois Colette , Axelin Anna , Pölkki Tarja
Published: September 2024

Aim

To evaluate the feasibility of the Swiss complex interprofessional intervention, NEODOL© (NEOnato DOLore), for improving the management of procedural pain in neonates in the Finnish context.

Background

Interprofessional collaboration is important for all professionals involved in the care of neonates and for neonates' parents, to understand the appropriate use of non‐pharmacological and/or pharmacological methods for each pain situation and how to assess pain in real‐life situations. Appropriate methods of pain relief for neonates should be preferred as they protect the development of the neonate's brain.

Design

A descriptive qualitative design.

Method

Data were collected through semi‐structured focus group discussions following the Medical Research Council's framework for evaluation of complex interventions, in this case NEODOL© which aims to improve the procedural pain management of neonates. A purposive sample (n = 13) included eleven professionals representing various professions within Finnish Neonatal Intensive Care Units and two parents of infants who have received care in a Neonatal Intensive Care Unit. Data were analysed using inductive content analysis, and the results were reported in accordance with the COREQ guidelines.

Results

Professionals' and parents' evaluations suggest that NEODOL© is feasible, because it is consistent and addresses a current need. They assessed its overall content to be relevant and accessible, and its components to be internally coherent. However, they emphasise the need for further evaluation and refinement of the intervention to achieve the desired outcomes and cost‐effectiveness.

Conclusions

While NEODOL© is considered feasible, it requires further evaluation and refinement in the local context of each hospital before implementation.
Developing Relational Pedagogical Techniques in Comparative Christian–Muslim Courses
Authors: Nickel Breanna J.
Published: September 2024

The article acknowledges the limits of the categories of similarity and difference in undergraduate comparative religion courses. To challenge these limitations, including the potential for dualistic or “us/them” thinking, several pedagogical attempts to increase relationality in Christian–Muslim courses are explored. Relational methods include emphasizing living and public interreligious conversations during class segments on scriptural figures as well as humanizing perpetrators of religiously motivated violence.
A multispecies study reveals the diversity and potential regulatory role of long noncoding RNAs in cucurbits
Authors: Villalba‐Bermell Pascual , Marquez‐Molins Joan , Gomez Gustavo
Published: September 2024

Plant long noncoding RNAs (lncRNAs) exhibit features such as tissue‐specific expression, spatiotemporal regulation, and stress responsiveness. Although diverse studies support the regulatory role of lncRNAs in model plants, our knowledge about lncRNAs in crops is limited. We employ a custom pipeline on a dataset of over 1000 RNA‐seq samples across nine representative species of the family Cucurbitaceae to predict 91 209 nonredundant lncRNAs. The lncRNAs were characterized according to three confidence levels and classified by their genomic context into intergenic, natural antisense, intronic, and sense‐overlapping. Compared with protein‐coding genes, lncRNAs were, on average, expressed at low levels and displayed significantly higher specificity when considering tissue, developmental stages, and stress responsiveness. The evolutionary analysis indicates higher positional conservation than sequence conservation, probably linked to the conserved modular motifs within syntenic lncRNAs. Moreover, a positive correlation between the expression of intergenic/natural antisense lncRNAs and their closest/parental gene was observed. For those intergenic, the correlation decreases with the distance to the neighboring gene, supporting that their potential cis‐regulatory effect is within a short‐range. Furthermore, the analysis of developmental studies showed that a conserved NAT‐lncRNA family is differentially expressed in a coordinated way with their cognate sense protein‐coding genes. These genes code for proteins associated with phloem development, thus providing insights about the potential involvement of some of the identified lncRNAs in a developmental process. We expect that this extensive inventory will constitute a valuable resource for further research lines focused on elucidating the regulatory mechanisms mediated by lncRNAs in cucurbits.
Arabidopsis hydathodes are sites of auxin accumulation and nutrient scavenging
Authors: Routaboul Jean‐Marc , Bellenot Caroline , Olympio Aurore , Clément Gilles , Citerne Sylvie , Remblière Céline , Charvin Magali , Franke Lars , Chiarenza Serge , Vasselon Damien , Jardinaud Marie‐Françoise , Carrère Sébastien , Nussaume Laurent , Laufs Patrick , Leonhardt Nathalie , Navarro Lionel , Schattat Martin , Noël Laurent D.
Published: September 2024

Hydathodes are small organs found on the leaf margins of vascular plants which release excess xylem sap through a process called guttation. While previous studies have hinted at additional functions of hydathode in metabolite transport or auxin metabolism, experimental support is limited. We conducted comprehensive transcriptomic, metabolomic and physiological analyses of mature Arabidopsis hydathodes. This study identified 1460 genes differentially expressed in hydathodes compared to leaf blades, indicating higher expression of most genes associated with auxin metabolism, metabolite transport, stress response, DNA, RNA or microRNA processes, plant cell wall dynamics and wax metabolism. Notably, we observed differential expression of genes encoding auxin‐related transcriptional regulators, biosynthetic processes, transport and vacuolar storage supported by the measured accumulation of free and conjugated auxin in hydathodes. We also showed that 78% of the total content of 52 xylem metabolites was removed from guttation fluid at hydathodes. We demonstrate that NRT2.1 and PHT1;4 transporters capture nitrate and inorganic phosphate in guttation fluid, respectively, thus limiting the loss of nutrients during this process. Our transcriptomic and metabolomic analyses unveil an organ with its specific physiological and biological identity.
Simulation of Interfacial Waves in Core-Annular Pipe Flow With a Turbulent Annulus
Authors: Li Haoyu , Pourquié Mathieu , Ooms Gijs , Henkes Ruud
Published: September 2024

Numerical simulations are conducted for the wave initiation, growth, and saturation at the oil–water interface in core-annular flow (CAF). The focus is on conditions with a turbulent water annulus, but the laminar water annulus is also considered. The simulation results are compared with lab measurements. The growth rate for the linear instability of different wavelengths in the case of a turbulent water annulus is obtained from two-dimensional (2D) axisymmetric Reynolds-averaged Navier–Stokes (RANS) simulations with the Launder–Sharma low-Reynolds number k–ε model. The latter simulation results provide the most unstable wavelength for the turbulent water annulus. Our study also shows the following. The maximum wave growth rate for a turbulent water annulus is significantly higher than for a laminar water annulus. The most unstable wavelength in the simulations is about 25% smaller than in the experiments. The wave amplitude for the different wavelengths in the simulations is typically 17% lower than in the experiments.
On Using the Distributor as a Multi Degree-of-Freedom System to Mitigate the Pressure Pulsation in an Axial Turbine at Speed-No-Load
Authors: Kranenbarg Jelle , Jonsson Pontus P. , Mulu Berhanu G. , Sundström Joel , Cervantes Michel J.
Published: September 2024

Hydraulic axial turbines are more frequently utilized for grid regulation purposes. Sometimes, they must be operated at speed-no-load (SNL) conditions, which is characterized for some machines by a varying number of large vortical flow structures extending from the vaneless space to the draft tube, introducing detrimental pressure pulsations throughout the turbine. A recent study shows that the vortices can be mitigated by individually controlling the guide vanes. Since optimization of the distributor layout is linked with a large degree-of-freedom, machine learning is deployed to assist in finding an optimal setup cost-effectively. A reduced numerical computational-fluid-dynamics (CFD) model is built and used to generate input for Gaussian process regression surrogate models by performing 2000 steady-state simulations with varying distributor layouts. The surrogate models suggest that the optimal layout is to open seven out of 20 guide vanes in succession while keeping the remaining ones closed. However, this configuration induces large radial forces on the runner, and after implementing some modifications by trial and error, detailed time-dependent CFD simulations show that placing 4 + 3 opened guide vanes on opposite sides of the runner axis is better; it reduces the pressure peaks corresponding to a two- and three-vortex configuration, and the maximal pressure pulsations by as much as 88% in the vaneless space compared to regular SNL operation. Meanwhile, the radial force on the runner is reduced by more than 83%, and pressure pulsations on the runner blades by more than 55%, compared to the surrogate models' optimal layout prediction.
Study of the Flow Characteristics of Pumped Media in the Confined Morphology of a Ferrofluid Pump With Annular Microscale Constraints
Authors: Li Wangxu , Li Zhenggui , Han Wei , Li Decai , Yan Shengnan , Zhou Juping
Published: September 2024

The driving mechanism of ferrofluid micropumps under the constraints of an annular microscale morphology is not fully understood. The gap between microfabrication technology and the fundamental theory of microfluidics has become a substantial obstacle to the development and application of ferrofluid micropumps. In this study, we first theoretically analyzed the Knudsen numbers of millimeter-scale microfluids using Jacobson's molecular hard sphere model, obtaining the initial conclusion that liquid flow conforms to the continuum hypothesis in geometric morphologies with characteristic dimensions greater than 7 × 10−8 m. Subsequently, using a microscopic lens combined with the particle image velocimetry optical measurement method, the flow patterns in millimeter-scale annular flow channels were captured and we observed wall slip phenomena in which the slip length of the millimeter-scale channel approached the micron level. The slip velocity and flowrate through the cross section of the microscale channel followed a logarithmic function relationship and could be divided into rapid growth, slow growth, and stable stages. As the characteristic scale of the channel was further reduced, the linear relationship between the slip velocity and cross-sectional flowrate in the rapid growth stage was broken, and the nonlinear relationship approximated an exponential function. Finally, a theoretical model for the flow behavior of the driving fluid in a ferrofluid micropump was established using slip boundary conditions. The flow patterns in microscale ring flow under slip conditions conformed to a quadratic function.
Effect of Trailing Edge and Span Morphing on the Performance of an Optimized NACA6409 Wing in Ground Effect
Authors: Clements Dominic , Djidjeli Kamal
Published: September 2024

A computational fluid dynamics (CFD) investigation was carried out on a three-dimensional NACA6409 wing in ground effect at a Reynolds number of 320,000. Using a multi-objective-SHERPA algorithm, a root angle of 4 deg angle of attack, a tip angle of 6 deg, a forward sweep, and a tip chord of 20% of the root chord produced an optimum aerodynamic efficiency across all ground clearances. Optimization showed a gain in aerodynamic efficiency of 41% at h/c = 0.05 ground clearance and a 31% gain at h/c = 0.2 compared to a rectangular planform wing. Next, fish bone active camber (FishBAC) morphing was applied to the optimized wing varying the morphing start locations along the chord at both the tip and root. A later start location produced the highest aerodynamic efficiency but increased manufacturing complexity. Extendable span morphing was also tested and was found that increasing the span from 1c to 1.5c increased the aerodynamic efficiency of the optimized wing by 27.4% at h/c = 0.1. Varying the span from 0.8c to 1.2c in ground effect had a small effect on the drag for small ground clearances; for large ground clearances, the total drag decreased as the span increased. Smaller gains were seen when the span morphing was applied to the rectangular wing. The FishBAC morphing was applied in the spanwise direction to morph the wingtip, sealing the flow beneath the wing. Also, the proportion of the morphing wingtip caused the trailing edge to be closer to the ground further enhancing ground effect.
Oblique Wave Scattering by a Pair of Asymmetric Inverse Π-Shaped Breakwater
Authors: Sharma Priya , Sarkar Biman , De Soumen
Published: September 2024

The topic of wave scattering by different breakwaters has unfolded over the past few decades, largely driven by the profound impacts of global climate change. In this study, a completely new type of breakwater, inverse Π-shaped breakwater, has been taken into account for serving both purposes from analytical as well as an application point of view. During the formulation, the actual physical problem is transferred into a boundary value problem by employing the small amplitude water wave theory. With the aid of eigenfunction expansion, the problem is reduced to a set of integral equations having square-root singularities at the submerged edges of thin structures. To address such singularities, a multi-term Galerkin approximation technique is used along with Chebyshev polynomials (multiplied with suitable weights) as basis functions. The numerical methodology employed here validates with different previous literatures as special cases. Then, numerical solutions of the reflection and transmission coefficients, hydrodynamic forces are graphically illustrated across various dimensionless structural parameters. In summary, the present paper offers valuable insights into the dynamics of wave scattering by a pair of asymmetric inverse bottom-mounted Π-shaped breakwater, emphasizing the role of different non-dimensional parameters in this system.
Effects of Aerodynamic Damping and Gyroscopic Moments on Dynamic Responses of a Semi-Submersible Floating Vertical Axis Wind Turbine: An Experimental Study
Authors: Jiang Yingying , Cheng Zhengshun , Chen Peng , Liu Lei , Yang Lijun , Xiao Longfei
Published: September 2024

Floating vertical-axis wind turbines (VAWTs) offer certain advantages over floating horizontal-axis wind turbines (HAWTs), particularly in terms of the potential to lower the cost of energy. In this study, a 5 MW floating VAWT concept with three straight blades and a semi-submersible hull deployed in a water depth of 42 m was presented. In addition, the experimental setup is introduced, and calibration tests are also performed to validate the physical model system. Subsequently, the aerodynamic damping and gyroscopic moment effects were investigated by wind/wave basin model tests with a scale ratio of 1/50. Results indicate that aerodynamic damping can suppress the fluctuations of the platform's surge and pitch motion at their respective resonance frequencies and tends to increase with wind speed at below-rated wind speed. Additionally, surge-induced and pitch-induced aerodynamic damping hardly affect the wave frequency response. Meanwhile, the surge natural frequency is substantially altered due to the wind loads. The rotating rotor and pitch motion of the platform together excite significant gyroscopic moments, leading to noticeable oscillations in roll motion. Additionally, there is an increasing trend in the gyroscopic moment effect with rotational speed. During normal operation of the floating VAWT, aerodynamic damping and gyroscopic moment together influence hull roll/pitch motions. Overall, this study contributes to providing valuable insights into the motion characteristics of floating VAWTs.
Evolution of Lubrication Characteristics of Double-Nut Ball Screws Based on an Efficient Surface Roughness Modeling Method
Authors: Shen Junwan , Zhou Changguang , Feng Hutian , Chen Zengtao
Published: September 2024

Accurate prediction of lubrication characteristics, specifically film thickness and pressure distribution, is pivotal for ensuring optimal performance in ball screws. Despite its significance, there is a notable dearth of studies investigating the evolution of lubrication characteristics resulting from the changing surface roughness over prolonged operation of ball screws. Furthermore, obtaining the surface roughness of ball screws poses a challenge due to the limited loading capacity of measurement instruments. Traditional methods involving cutting the screw for surface roughness measurement are impractical for continuous monitoring during extended operation. To address this issue, the present study introduces an efficient approach to model the surface roughness of the raceway in double-nut ball screws. A profilometer is employed to measure profile roughness along two directions (parallel and perpendicular to the rolling direction) without the need to cut the screw raceway. The 2D power spectral densities and height probability densities of profile roughness are calculated to model the surface roughness, and the synthesized data are utilized to solve the Reynolds equation. The simulation method is validated through friction torque tests, demonstrating a calculation accuracy exceeding 92%. The study further explores the evolution of film thickness and pressure distribution in double-nut ball screws during running-in and steady wear stages, revealing severe asperity contact in the two nuts. Additionally, variations in load ratio, friction coefficient, and film thickness ratio (λ) are investigated. Considering the load ratio and λ of the slave nut, it can be inferred that boundary lubrication persists in the two nuts throughout the operation.
Anisotropy in Chip Formation in Orthogonal Cutting of Rolled Ti-6Al-4V
Authors: Tamura Shoichi , Matsumura Takashi
Published: September 2024

The increasing demand for titanium alloys in aerospace and medical device industries stems from their lightweight and high strength properties. Enhancing machining technologies for titanium alloys is critical for reducing production time and costs. This study investigates the anisotropy in machining of rolled titanium alloy plates with orthogonal cutting tests. The mechanical properties of these plates exhibit anisotropy due to the rolled texture of hexagonal close-packed (HCP) structure. Observations of chip morphologies and cutting forces are conducted with changing cutting direction angles relative to the rolling direction. The result shows that the chip morphology is influenced by the cutting direction angle. When cutting parallel to the rolling direction with an orthogonal cutting tool with 30-deg rake angle, serration free chips are produced, while perpendicular cutting results in serrated chips. The chip thickness, the serration pitch, and the serration length vary with the cutting direction angle. The serration length is associated with an anisotropic deformation index, which characterizes anisotropic behavior in chip formation. Lower index values suppress the formation of undesirable serrated chips. It is expected that the anisotropic deformation index will be applied to the control of serrated chip formation in practical machining processes.
Frequency Domain Analysis of Transient Discharge Pressure Harmonics for Clogging Detection in Wastewater Pumps
Authors: Brokhausen Florian , Rost Lena Marie , Thamsen Paul Uwe
Published: September 2024

Due to the heterogeneous nature of wastewater, the operation of wastewater pumps exhibits challenges beyond the optimization of efficiency and hydraulic performance. Instead, operationality is a paramount feature. The main cause for malfunctions in wastewater pumps is the phenomenon of clogging of the pump impeller to a state of total blockage. There exist automatic procedures to resolve this type of clogging, most prevailing the so-called cleaning sequence. However, the current implementation in practice exhibits the downside of under-determined triggering solutions. This work presents a step towards the identification of the clogging state of a pump and the subsequent leverage as a trigger for an automated cleaning sequence. By analyzing the discharge pressure of an exemplary wastewater pump in the frequency domain, intricate characteristics in salient frequencies are demonstrated to be an indicative proxy for the clogging state of the pump impeller. In detail, the pump under observation showed a highly increased amplitude at the blade passing frequency as well as its second harmonic. Compared to clear water operation, the magnitude of these pressure pulsations showed an average increase of over 600% due to clogging of the impeller.
Effects of Reynolds Number, Mudflap Configuration and Loading Shape on the Wake of an Earthmoving Dump Truck: A Wind Tunnel Study
Authors: Obeid Bachar , Durán García Edwin , Murzyn Frédéric , Muresan-Paslaru Bogdan , Razakamanantsoa Andry
Published: September 2024

Heavy-duty dump trucks are an important source of particle emissions. When traveling on unpaved roads, they emit particles through wear and resuspension mechanisms. The particles are then dispersed by the turbulence created in the vehicle wake, leading to a deterioration of air quality in and around construction sites. A better understanding of the truck’s wake flow dynamics is therefore required to get a better knowledge of the resuspended particle dynamics. In the present work, the effects of Reynolds number, mudflap configuration, and load shape on the wake flow topology of an earthmoving dump truck are experimentally investigated in a wind tunnel study. 2D LDV measurements are conducted in the wake of a reduced-scale (1:50) dump truck. Three different velocities are studied (8, 12, and 16 m/s), corresponding to a height-based Reynolds number (Reh) ranging from 36,216 to 72,432. Additionally, three configurations of mudflaps (without a mudflap, a single long mudflap, and two mudflaps behind the wheels) and three shapes of material loading (empty dumpster, flat load, and dome-shaped overload) are considered. The results show that the presence of a long mudflap results in the formation of a large vortex in the truck’s wake, which is supposed to increase particle emissions. The shape of the load also plays a key role. The dome-shaped overload increases the size of the vortices and the upward backflow that develop in the close wake of the vehicle, thus enhancing particle emission. Finally, a quadrant analysis of Reynolds shear stress shows that the long mudflap favors the appearance of sweep events in the upper shear layer and close to the ground, which is supposed to increase particle emissions.
New Theoretical Shock Loss Model for Axial Fans Based on the Integral Momentum Equation
Authors: Fritsche Manuel , Epple Philipp
Published: September 2024

To analyze the pressure characteristic behavior of axial fans during the design process, an analytical estimation of the pressure characteristic is of interest for industry and academia. The loss models for turbomachines are traditionally based on the energy equation, i.e. the Bernoulli equation, in combination with loss coefficient. Different than the energy conservation equation, the integral momentum equation can deliver the pressure loss term without any empirical loss coefficient.

In the present contribution, this issue has been addressed and the authors developed a new combined loss model especially for axial fans consisting of a slip factor model and a shock loss model. With the integral momentum approach, no empirical constants are needed for the shock loss model, in contrast to the energy equation-based models. In this work it is shown on the example of axial fan losses, that the integral momentum equation is a powerful method to estimate losses. This approach can also be extended to other applications and can be included on a broader basis in the classes of fluid mechanics and turbomachinery in the engineering education.

For validation, several axial fans have been computed with CFD using the commercial solver ANSYS CFX 2023 and compared with the theoretical characteristics computed with the Euler turbomachinery equation in combination with the new combined loss model of the authors. The comparison of the theoretical predictions based on the integral momentum equation and the numerical computations are in very good agreement, showing that the theoretical loss model produces very reliable results and full axial fan characteristics.
Influence of Monovalent and Divalent Salts on Oil-Water Emulsion Stabilized by Nonionic Surfactants
Authors: Alanazi Khalid , Mohan Ram , Kolla Srinivas Swaroop , Shoham Ovadia
Published: September 2024

It is still unclear how the presence of certain ions influences nonionic surfactant-stabilized emulsions. Hence, the purpose of this work is to investigate the effect of monovalent (NaCl) and divalent (CaCl2) ions on an oil-water emulsion stabilized by two different nonionic surfactants, Tergitol 15-S-7 (T15S7) and Span® 80 (SP80). Emulsions were formed in a 60 mm gravity-based separator of a nominal volume of 200 ml. In addition to a wide range of ion concentration, the study looked at the effect of low (800 RPM) and high (2500 RPM) mixing speeds at water-to-oil ratios (WORs) of 1:3 and 3:1. At low mixing speeds and WORs, experimental results showed that the presence of ion (regardless of its concentration or type) does not affect emulsions stabilized by SP80. However, when mixed at higher speeds, ions were shown to increase the volume of the same system. Data of SP80-stabilized emulsions also showed that the increase of WOR from 1:3 to 3:1 causes a significant drop in the volume of the emulsion regardless of ion type and/or concentration. On the contrary, at a WOR of 1:3, the presence of ions was shown to reduce the volume of T1S57-stabilized emulsions. However, although mixed at two different speeds, the separation kinetics of T15S7-stabilized emulsions became salt-independent after a few hours of formation.
Development of a Diffuser Type Multistage Pump With Low Specific Speed
Authors: Kim Joshua Joohyen , Kim Dohong , Kim Hyeonsig , Boehle Martin
Published: September 2024

Multistage pumps delivering small flow-rate at very high-head are used for fertilizer, chemical, oil production, and power plant. Low specific speed (nq) pumps often show insufficient head-rise to zero-flow, unstable head-curve, and low efficiency. The current study presents a development procedure of hydraulic components for a diffuser-type multistage pump at nq = 12.9 [m3/s, m, rpm] and test results of 4-stage pump. Various design methods were applied to the new impeller and diffuser to increase shut-off head such as an extended-cut leading-edge, tight gap of between impeller and diffuser side plates and so on. The measured head-curve was stable with a head-rise ratio over 1.2 from BEP to shut-off. CFD simulation results showed that the kinetic energy of fluid could not be sufficiently converted into the potential energy in the guide-vane channels due to the compact construction of the low nq pump. A continuous diffuser consisting of guide-vanes, cross-over channels, and return-vanes was designed and optimized based on flow-quality analysis to achieve a high efficiency and flat efficiency-curve near BEP. Two types of seal patterns, rectangular grooves and plain, were applied on the front wear-ring and balance drum. The measurement outputs were compared and the impact of leakage on pump performance at the low nq were discussed.
Physics-Based Design and Optimization Strategy for Low-Pressure Axial Fans
Authors: Fritsche Manuel , Epple Philipp
Published: September 2024

For cost and manufacturing reasons, low-pressure axial fans are typically manufactured with three-dimensionally curved sheet metal blades of constant thickness. However, the design method for low-pressure axial fans presented in this work is also suited for the design of axial fans with thin blades. In addition, there is an increasing demand for a free shaped hub geometry, for example a conical hub contour.

In the extended design strategy, the concept of the radial equilibrium is applied under the specification of a blade work distribution in the form of a design total pressure distribution in the radial direction on five partial flow sections. In addition, the radial equilibrium and the specified design total pressure distribution are also specified on five sections in the axial direction along the blade. This method is based on the application of pure analytical physics-based equations, which are solved on each partial flow section in the radial and axial direction and allows a detailed design of the blade geometry.

Furthermore, the presented analytical extended design strategy has been optimized using statistical methods. This has been performed with ANSYS CFX 2023 and the ANSYS Workbench. For this purpose, a meta-model-based optimization strategy for the designed blade angles is proposed. The iterative application of the indirect optimization process, consisting of a DOE analysis, a response surface method (RSM) and a subsequent multi-objective optimization on the axial section in the direction of flow is efficient and effective.

Finally, the extended design and optimization strategy has been applied and verified with numerical and experimental data. The comparison of the characteristics of the measurement data with the numerical CFD results showed a very good agreement and the accuracy and reliability of the developed CFD model have been validated.
A Numerical Investigation of the Longitudinal Vortex Pair Structure in Underbody Diffuser Flows
Authors: Mayoral Salvador , Massis Anthony
Published: September 2024

An automotive diffuser is an open channel within the under-body of a vehicle that features a diverging ramp in the aft section. The performance of a diffuser is sensitive to ground effect where decreases in ride height result in increases in downforce. However, below a critical value, any further reduction in ride height results in a significant loss of downforce. Previous experimental investigations demonstrated that the dominant flow feature within underbody diffuser flows is a pair of counter-rotating longitudinal vortices, and the resulting downforce behavior is directly linked to the structure of the longitudinal vortex pair. This study investigates the effect of ride height on the behavior of the longitudinal vortex pair within an underbody diffuser flow in ground effect. The unsteady flow past a diffuser-equipped bluff body with a 17° diffuser ramp angle is simulated using large eddy simulation with wall-stress modeling, commonly referred to as wall modeled large eddy simulation (WMLES). The flow Reynolds number based on body length is 1.75 × 106. Numerical simulations are performed with OpenFOAM and WMLES is implemented with libWallModelledLES, a third-party WMLES library for OpenFOAM. Results show that the mean center-line surface pressure distributions along the underbody match well with experiments. Visualization of the vortices with isosurfaces of the Q-criterion demonstrates that the longitudinal vortices experience a spiral-type vortex breakdown which propagates upstream with decreasing ride height.
Analysis of Flow Field Under Unsteady Breathing Conditions in a Realistic Human Nasal Cavity
Authors: Shahed Syeda Reham , Tian Lin , Dong Jingliang , Tu Jiyuan , Zhang Ya , Ma Ruiping , Ahmadi Goodarz
Published: September 2024

The human nasal airway is a complex structure that provides the first line of defense to filter foreign particles before reaching the lungs. With the increased occurrence of nasal and nasopharyngeal cancers, understanding nasal airflow dynamics is crucial to assessing the potential airflow-related causes. Although human respiration is inherently unsteady, many earlier studies have been conducted for an effective steady breathing state. In this study, we analyzed unsteady respiration in a realistic human nasal cavity using the Ansys-Fluent software. A sinusoidal inhalation and exhalation at peak breathing of 10 1/min was simulated. It was found that the inhalation and exhalation breathing show different airflow dynamics. In particular, significant reversed flow conditions were observed at the entrance to the main nasal cavity from the pharynx during the exhalation phase. Both inhalation and exhalation exhibit significant acceleration and deceleration phases, with more prominent vortices forming during the deceleration phase of the inhalation period. Particular attention was given to the unsteady airflow condition in turbinate and olfactory regions. Our study showed that transient breathing in the nasal cavity and its impact on particle deposition needs further investigation.
Computational Studies on Droplet Dynamics in Microtubes With Rough Surface via Spectral Elements
Authors: Melbye Julie , Wang Yechun
Published: September 2024

A plethora of studies have investigated the motion of liquid droplets in microtubes or microchannels as technologies in microfluidics developed rapidly in recent decades. Most computational studies on this topic assumed smooth inner surface for the fluid conduit. However, there are few studies that consider the roughness of the inner surface that could affect the droplet motion, especially for the cases in which the roughness size is comparable to that of the droplet. In this study, we employ a 3D spectral boundary element method for interfacial dynamics to examine the droplet translation, migration, and deformation in a micron-sized cylindrical tube with a rough inner surface. The roughness feature of the surface is comparable to the size of the droplet and is simulated with sinusoidal functions. The computational results show that the surface roughness significantly affects the behavior of a deformable droplet, including its deformation as well as the speed of translation. The results of this study could provide contribution to the development of microfluidics.
Characteristics of Turbulent Flow Around Right-Trapezoidal Prisms With Varying Upper and Lower Lengths
Authors: Guney Aleyna , Abdul-Salam Fati Bio , Sagharichi Amir , Tachie Mark F.
Published: September 2024

The turbulent characteristics of flow separation induced by trapezoidal prisms subjected to uniform flow are studied using particle image velocimetry (PIV). The streamwise aspect ratios (upper length to lower length) were AR1.0_2.5, AR2.0_2.5, and AR2.0_4.0. The Reynolds number (based on freestream velocity and body height) was Reh = 10000 and the results were analyzed in terms of the mean velocities, Reynolds stresses, and proper orthogonal decomposition. Recirculation bubbles formed in the wake region are asymmetric about the prism centerline, and the lower bubble is smaller than the upper one. Contours of the streamwise Reynolds normal stress exhibit two peaks in the wake of the prisms, and an additional peak over the upper surface of the prism. The peak magnitude of streamwise Reynolds normal stress in the upper and lower wake region are identical. A single peak in the vertical Reynolds normal stress is observed near the centerline of the prism within the wake region. Proper orthogonal decomposition was used to characterize the energetic vortical structures of the flow field around the prisms. The results show that the first two POD modes capture similar relative energy content, regardless of aspect ratio, while the wavelength of the POD decreases as the aspect ratio increases.
Computational Study of Noise Control of Different Sound Reducing Materials Surrounding Wind-Tunnels
Authors: Si Xiuhua , Bartlett Gabriel , Xi Jinxiang
Published: September 2024

Wind tunnels are frequently utilized in aerospace industries and universities for research, design, or demonstration purposes. However, they can generate high volumes of noise, especially at high wind speeds, posing acoustic hazards to those nearby. Thus, minimizing noise generation from wind tunnels is paramount, especially when the wind tunnel is located within a building shared by many others. Considering that sound generation can be attributed to structural vibroacoustics and flow aeroacoustics, this study aimed to design an effective sound reduction insert using varying materials to reduce noise generation in a newly developed wind tunnel at CBU. In addition to theoretical analyses, COMSOL simulations were conducted to design and optimize the shape, size, and material of the sound-dampening insert. Several materials were selected for their acoustic transmission properties and were systematically tested in wind tunnel settings by varying their thicknesses, shapes, and combinations with other materials. Aeroacoustics simulations demonstrated that the optimal material for sound dampening is gypsum board, with a trapezoidal shape, and a backbone of plywood material.
Techno-Economic Assessment of Urban Wind Energy Near Various Common Building Configurations
Authors: Mortazavian Javad , Goudarzi Navid
Published: September 2024

Urban wind energy has become a popular source of sustainable power in modern urban configurations. This study aims to analyze the technical and economic aspects of installing wind-harnessing devices near different common urban configurations. Computational fluid dynamics simulations utilized by Reynolds-Averaged Navier-Stokes equations and realizable k-ϵ turbulence model are used to model the turbulent urban canopy layer in the vicinity of four different urban settings namely an isolated high-rise building model, and 3 clusters of buildings with different central building heights, ranging from no building to a high-rise building model. Normalized wind power density (PD) and turbulence intensity (TI) contours were plotted to identify areas of interest to install urban wind turbines. To show the significance of this research, the levelized cost of energy was calculated for an urban horizontal axis wind turbine installed at locations with the highest wind PD and lowest TI values. The results indicated that while the highest wind PD locations and their values change with the selected configuration, promising regions can be identified for wind harnessing applications.
A primary wideband calibration method for noise hydrophones based on three-transducer spherical wave reciprocity in the frequency domain
Authors: Jia Guanghui , Chen Yi , Tu Juan , Zhang Dong
Published: September 2024

A primary wideband calibration method for noise hydrophones is developed, which can be applied to obtain noise acoustic spectral density sensitivity in the free-field. In this method, a wideband three-transducer spherical wave reciprocity calibration method is proposed in the frequency domain. A lowpass spatial domain filter is utilized to eliminate the reflecting acoustic waves from boundaries and water surface, and the wideband frequency responses of the transducer pair are calculated. Wideband calibrations are performed in a laboratory anechoic water tank, and two hydrophones with different reference sensitivities are calibrated in the frequency range of 250 Hz to 20 kHz using noise signals. The decidecade band sensitivities are obtained by the primary wideband calibration, which is in agreement with the single frequency sensitivities. The expended uncertainty of the primary wideband calibration is analyzed and estimated to be 8.9% (k = 2).
Multispecies initial numerical validation of an efficient algorithm prototype for auditory brainstem response hearing threshold estimation
Authors: Petersen Erik A. , Shen Yi
Published: September 2024

The auditory brainstem response (ABR) can be used to evaluate hearing sensitivity of animals. However, typical measurement protocols are time-consuming. Here, an adaptive algorithm is proposed for efficient ABR threshold estimation. The algorithm relies on the update of the predicted hearing threshold from a Gaussian process model as ABR data are collected using iteratively optimized stimuli. To validate the algorithm, ABR threshold estimation is simulated by adaptively subsampling pre-collected ABR datasets. The simulated experiment is performed on 5 datasets of mouse, budgerigar, gerbil, and guinea pig ABRs (27 ears). The datasets contain 68–106 stimuli conditions, and the adaptive algorithm is configured to terminate after 20 stimuli conditions. The algorithm threshold estimate is compared against human rater estimates who visually inspected the full waveform stacks. The algorithm threshold matches the human estimates within 10 dB, averaged over frequency, for 15 of the 27 ears while reducing the number of stimuli conditions by a factor of 3–5 compared to standard practice. The intraclass correlation coefficient is 0.81 with 95% upper and lower bounds at 0.74 and 0.86, indicating moderate to good reliability between human and algorithm threshold estimates. The results demonstrate the feasibility of a Bayesian adaptive procedure for rapid ABR threshold estimation.
The Efficacy of Ischemic Preconditioning on Handgrip Strength and Strength Endurance in Para-Athletes With Spinal-Cord Injury: A Pilot Study
Authors: Kasofsky Lexi , Cross Rebecca , Tavoian Dallin , Siegler Jason
Published: September 2024

Purpose: This pilot study investigated the functional outcomes after ischemic preconditioning (IPC) in high-level para-athletes with spinal-cord injury. Methods: Nine athletes completed 2 handgrip exercise trials (an isometric hold to failure at 60% maximal voluntary contraction [ISO] and a progressive, intermittent handgrip to failure [INT]), preceded by either IPC (220 mm Hg) or sham (20 mm Hg) for six 5-minute periods, in a repeated-measures, crossover design. Results: Although small performance improvements in time to task failure were observed in the ISO (∼5%) and INT (∼8%) IPC conditions, which are similar to those reported elsewhere, no statistical influence was observed (ISO–IPC, 74.2 [32.6] s; SHAM, 70.7 [27.2] s; P = .73; INT–IPC, 426.0 [80.1] s; SHAM, 392.2 [42.5] s; P = .35). Fatigue was evident in the forearm muscle force (maximal voluntary contraction) ISO (mean decline of 178.1 [76.0] N [95% CI, −10.4 to 366.7 N]; P < .05) and INT (mean decline of 182.2 [72.5] N [95% CI, 34.5–329.8 N]; P < .05) trials but not different between treatments (P > .95). Conclusions: Although small performance improvements in time to task failure were observed, the findings of the present data set suggest that acute bouts of IPC do not meaningfully influence fatigue during handgrip exercise in para-athletes with spinal-cord injury.
Synergistic antimicrobial combination of third-generation cephalosporins and polymyxin B against carbapenem-polymyxin-resistant
Klebsiella pneumoniae:
an
in vitro
and
in vivo
analysis
Authors: Sturaro Mariana Carvalho , Damaceno Nathalia da Silva , Faccin Izadora Dillis , Silva Osmar Nascimento , de Aquino Thiago Mendonça , Freire Nathalia Monteiro Lins , Alcântara Marcone Gomes dos Santos , Monteiro Kadja Luana Chagas , Rossato Luana , de Souza Gleyce Hellen de Almeida , Simionatto Simone
Published: September 2024

Antibiotic combination therapy is a promising approach to address the urgent need for novel treatment options for infections caused by carbapenem-polymyxin-resistant
Klebsiella pneumoniae
(CPR-Kp). The present study aimed to investigate the synergistic potential of four cephalosporins in combination with polymyxin B (PMB). A checkerboard assay was performed to evaluate the synergistic effects of cephalexin (CLX), cefixime, cefotaxime (CTX), and cefmenoxime (CMX) in combination with PMB. Subsequently, experiments evaluating the use of CTX or CMX in combination with PMB (CTX-PMB or CMX-PMB, respectively), including growth curve and SynergyFinder analysis, antibiofilm activity assays, cell membrane integrity assays, and scanning electron microscopy, were performed. Safety assessments were also conducted, including hemolysis and toxicity evaluations, using
Caenorhabditis elegans
. Furthermore, an
in vivo
model in
C. elegans
was adopted to assess the treatment efficacy against CPR-Kp infections. CTX-PMB and CMX-PMB exhibited low fractional inhibitory concentration indexes ranging from 0.19 to 0.50 and from 0.25 to 1.5, respectively, and zero interaction potency scores of 37.484 and 15.076, respectively. The two combinations significantly reduced growth and biofilm formation in CPR-Kp. Neither CTX-PMB nor CMX-PMB compromised bacterial cell integrity. Safety assessments revealed a low hemolysis percentage and high survival rates in the
C. elegans
toxicity evaluations. The
in vivo
model revealed that the CTX-PMB and CMX-PMB treatments improved the survival rates of
C. elegans
. The synergistic effects of the CTX-PMB and CMX-PMB combinations, both
in vitro
and
in vivo
, indicate that these antibiotic pairings could represent effective therapeutic options for infections caused by CPR-Kp.
The class III phosphatidylinositol 3-kinase VPS34 supports EV71 replication by promoting viral replication organelle formation
Authors: Wu Bo , Fan Tingting , Chen Xinrui , He Yingli , Wang Hongliang
Published: September 2024

Enterovirus 71 (EV71) belongs to the family of
Picornaviridae
; it could cause a variety of illnesses and pose a great threat to public health worldwide. Currently, there is no specific drug treatment for this virus, and a better understanding of virus-host interaction is crucial for novel antiviral development. Here, we find that the class III phosphatidylinositol 3-kinase, VPS34, is an essential host factor for EV71 infection. VPS34 inhibition with either shRNA or specific chemical inhibitor significantly reduces EV71 infection. Meanwhile, EV71 infection upregulates phosphatidylinositol 3-phosphate (PI3P) production in viral replication organelles (ROs), while the depletion of PI3P by phosphatase overexpression inhibits EV71 infection. In addition, the PI3P-binding protein, double FYVE-containing protein 1 (DFCP1), is also required for an efficient replication of EV71. DFCP1 could interact with viral 2C protein and facilitate viral association with lipid droplets (LDs), which are important lipid sources for viral RO biogenesis. Taken together, these results indicate that EV71 virus exploits the VPS34-PI3P-DFCP1-LDs pathway to promote viral RO formation and viral infection, and they also illuminate novel targets for antiviral development.

IMPORTANCE

Enterovirus 71 (EV71) is a major pathogen that causes hand-foot-and-mouth disease (HFMD) and other serious complications, which are big threats to children under 5 years old. Unravelling the interactions between virus and the host cells will open new avenues in antiviral research. Here, we found the class III phosphatidylinositol 3-kinase, VPS34, and its effector, double FYVE-containing protein 1 (DFCP1), were essential for EV71 infection, both of which could support EV71 viral replication by enhancing the biogenesis of viral replication organelles (ROs). As DFCP1 localizes to lipid droplets, hijacking of these host factors will enable viral utilization of lipids from LDs for the generation of membrane structures during RO biogenesis. In addition, the VPS34 kinase inhibitor was found to be potent against EV71 infection; therefore, this study also brings up a novel target for future anti-EV71 drug development.