bluuebunny/crossref_metadata_2025 huggingface dataset:
Trends in utilization of non‐first‐line topical acne medications among children, adolescents, and adults in the United States, 2012‐2016
Authors: Afarideh Mohsen , Rodriguez Baisi Katinna E. , Davis Dawn M.R. , Hand Jennifer L. , Tollefson Megha M.
Published: October 2021

Background/Objective

Current knowledge about usage of effective, but non‐first‐line topical acne medications in the United States is limited. We aimed to investigate utilization patterns and temporal trends for such acne medications in the US ambulatory care.

Methods

Pediatric (≤18 years old) and adult (>18 years old) data from the 2012 to 2016 (inclusive) cycles of the US National Ambulatory Medical Care Survey were extracted. Utilization patterns of six non‐first‐line topical acne medications (ie, azelaic acid, salicylic acid, glycolic acid, sulfur, resorcinol, and zinc) were compared and followed over time.

Results

Data from 218 410 US office–based sampled visits during 2012‐2016 were included in the analysis. Across all acne visits (n = 1542), salicylic acid (1.58%), azelaic acid (1.22%), and glycolic acid (0.52%) were the most frequently used agents, while zinc and resorcinol were not used. Sulfur (0.52%) and salicylic acid (0.33%) were the only medications used in preadolescents, and none of these medications were used in the neonatal or infantile group. Temporal trends for using at least one of these medications were insignificant among both pediatric and adult age groups (P = .825 and .136, respectively).

Conclusions

Salicylic acid and azelaic acid are the most frequently used of the studied second‐line medications to treat acne, although the use of these and the other non‐first‐line topical medications overall is uncommon, especially among younger groups of US pediatric patients.
BASCULE syndrome in a child with prior asymptomatic COVID‐19 infection
Authors: Berrebi Daniel , Farmer William , Zinn Zachary
Published: October 2021

BASCULE syndrome, characterized by Bier anemic spots, cyanosis, and an urticaria‐like eruption, has been described as a benign vasomotor dermatosis that occurs in the setting of transient tissue hypoxia. It has been postulated that dermal ischemia triggers an exaggerated vasoconstrictive arteriolar reaction, which then causes a paradoxical urticarial rash by an unknown mechanism. In patients with COVID‐19, there is evidence of angiocentric inflammation leading to vasoconstriction, endothelial damage, and thrombosis. We present a case of acute‐onset BASCULE syndrome appearing after asymptomatic infection with COVID‐19. BASCULE syndrome should be considered in the expanding spectrum of dermatologic manifestations associated with COVID‐19.
The effect of coronavirus disease 2019 on anxiety levels of children with cystic fibrosis and healthy peers
Authors: Yanaz Muruvvet , Yilmaz Yegit Cansu , Ergenekon Almala Pinar , Toksoy Aksoy Ayse , Bilicen Gulcin , Gokdemir Yasemin , Erdem Eralp Ela , Rodopman Arman Ayse , Karakoc Fazilet , Karadag Bulent
Published: October 2021

Background

Cystic fibrosis (CF) is a chronic disease causing recurrent respiratory tract infections. Viral respiratory tract infections are more severe in CF. The first case of coronavirus disease 2019 (COVID‐19) was seen in Turkey on March 11, 2020, and nationwide school closure and lockdown were implemented. School closure and home confinement might have adverse effects on children's physical and mental health. In this study, we aimed to compare the effect of the COVID‐19 pandemic on psychological reactions of CF patients and healthy controls.

Methods

This is a controlled cross‐sectional study including 7–18‐year‐old children with CF. The survey included questions regarding family environment and peer relations, self‐care, and psychological reactions to the COVID‐19 pandemic. The questionnaire was administered to children via telephone calls under parental supervision.

Results

We evaluated 132 CF patients and 135 of their healthy peers. Mean age was 11.5 ± 2.9 years in the CF group and 11.8 ± 3.2 years in the control group (P = 0.98). There were 55 girls (41.7%) in the CF group and 81 girls (60%) in the control group (P = 0.027). The socioeconomic status of their families was similar. The CF patients were found to be less anxious for family members at risk of COVID‐19, less upset about school closure, and less anxious about the COVID‐19 pandemic (P < 0.001, 0.02, 0.01, respectively).

Conclusions

Cystic fibrosis patients seem to show more resilience in coping with the pandemic. Appropriate psychological support should be provided to them and resilience strategies in coping with the pandemic should be nurtured.
Implementation facilitation of the “11 for Health in Denmark”: A case study in a Danish 5th grade class
Authors: Madsen Esben Elholm , Krustrup Peter , Møller Trine Kjeldgaard , Hansen Tina , Larsen Malte Nejst , Madsen Mads , Hansen Henrik Kruse , Elbe Anne‐Marie , Larsen Carsten Hvid
Published: October 2021

The “11 for Health in Denmark” concept aims to enhance 10–12‐year‐old schoolchildren's physical activity levels and health knowledge through an 11‐week football intervention and has been shown to induce positive effects in numerous areas. However, little is known about the implementation facilitation of this concept in schools. This case study therefore aims to gain a deeper understanding of the implementation facilitation of “11 for Health” in a Danish 5th grade class comprising 22 schoolchildren (12 boys and 10 girls, Mage 11.86±) and one teacher. Data were derived from multiple school situations using photographs and videos, observations, and informal interviews. Five themes were identified: (1) environmental and organizational factors impacting on the implementation; (2) familiarization with the concept for the teacher and schoolchildren; (3) previous clique formation; (4) the central role of the teacher; and (5) the importance of how praise partners are allocated. We found high adherence to the “11 for Health” concept, in which the teacher played a key role by applying an autonomy‐supportive style of teaching and using the praise partner concept in a suitable manner. A clique of football‐playing boys was a resource, as their praising of classmates encouraged adherence. However, familiarization with the “11 for Health” concept was a challenge and the clique's competitive nature occasionally built barriers to other schoolchildren without football experience, potentially leading to a more controlled form of motivation. Based on the results, we encourage teachers to apply autonomy‐supportive teaching when applying the “11 for Health” concept.
Troubling America's historical waters: Toward the transdisciplinary study of U.S. lynchings as an active present
Authors: Lewis Demar F.
Published: October 2021

This review considers a range of literatures that facilitate a critical discussion of lynching and legacies of lynching as present realities of the 21st Century in the United States of America. Although scholars in this field generally pride themselves on being “apolitical,” America's pioneering lynching scholars and anti‐lynching advocates desired to eradicate lynching because it tangibly threatened the safety of Black, racially minoritized, and resource‐deprived communities inside and outside of the U.S. South. However, scholars selectively engage this history despite its relevance to the production of their research. Likewise, routine displays of white supremacist violence throughout the COVID‐19 pandemic—including the lynching of Ahmaud Arbery—are exacerbating the health and welfare of communities that are already experiencing other inequities. This review mobilizes the Transdisciplinary Frame to address these concerns. This frame leverages the interventionist and anti‐racist praxes that created the field of lynching scholarship to advance an emancipatory sociology and scientific knowledge through the study of lynching's legacies. Furthermore, the Transdisciplinary Frame galvanizes scholars to use innovative methods to explore how racially minoritized individuals and resource‐deprived communities in the 21st Century are grappling with safety concerns that may or may not be tied to legacies of U.S. lynching.
Moral framings in the Australian parliamentary debate on drug testing of welfare recipients
Authors: Curchin Katherine , Weight Thomas , Ritter Alison
Published: September 2021

Around the world an expanding array of behavioural conditions are being attached to social security payments. This paper offers empirical evidence of the various moral frames used in the welfare conditionality debate, by its supporters and detractors. We systematically analyse the debates in the Australian federal parliament in 2017 and 2018 on two bills attempting to introduce drug testing of working‐age welfare recipients, each of which resulted in stalemate. We find that proponents of welfare conditionality primarily employed consequentialist and paternalist arguments, supplemented by social justice, contractualism and communitarianism whilst opponents primarily employed consequentialist and social justice arguments. We explore how proponents and opponents anticipated and engaged with each other's preferred moral frames. By investigating the normative lenses that underpin arguments made for and against the drug‐testing proposal, we shed light on how the debate on drug testing might be moved beyond its current impasse.
Clinical characteristics of and antibody response to spotted fever group rickettsial infections in South India: Case series and serological cohort study
Authors: Schmidt Wolf‐Peter , Devamani Carol S. , Elangovan Divyaa , Alexander Neal , Rose Winsley , Prakash John A. J.
Published: October 2021

Objective

The clinical and serological characteristics of spotted fever group rickettsial (SFGR) infections in South Asia are poorly understood. We studied the clinical presentation and the IgM/IgG response in cases enrolled at two health care centres in South India.

Method

We enrolled 77 patients. Fifty‐seven of these patients were recruited at a tertiary care centre, the remaining 20 at a community hospital (secondary care level). Diagnostic tests included IgM and IgG enzyme‐linked immunosorbent assay and polymerase chain reaction. Over a period of 1 year, 41 cases were followed up for repeated sero‐analysis.

Results

Median age was 9 years (range 1–79). A rash was present in 74% of cases (57/77). In cases aged <15 years, rash was present in 94% (44/47) vs. 43% (13/30) in cases aged ≥15 years. An eschar was found in two cases (3%). Severe infection or complications occurred in 10 cases (13%). These included central nervous system infection (6/77, 8%), kidney injury (3/77, 4%), shock (3/77, 4%), lung involvement (2/77, 3%) and peripheral gangrene (2/77, 3%). IgM antibody levels increased faster after fever onset than IgG antibodies, peaking at 50 and 60 days, respectively. After the peak, IgM and IgG levels showed a slow decline over one year with less than 50% of cases showing persistent IgG antibody levels.

Conclusion

Spotted fever group rickettsial infections in South India may be under‐diagnosed, as many cases may not develop a rash. The proportion of cases developing severe infection seems lower than for scrub typhus in this region. IgG seroprevalence may substantially underestimate the proportion in a population with past SFGR infection.
Pet‐owner perceptions of laparoscopy in an urban hybrid veterinary practice
Authors: Buote Nicole J. , Carney Patrick , Sumner Julia
Published: October 2021

Objective

To investigate owner perceptions of laparoscopic surgery, including attitudes towards paying more for minimally invasive surgery (MIS).

Study design

Randomized cross‐sectional prospective survey.

Sample population

One hundred owners presenting at a combined general and specialty practice.

Methods

Participants were interviewed using a survey tool to assess prior knowledge of laparoscopic procedures, attitude for or against these procedures, reasons for this attitude, and whether they would pay more for the procedures. Demographic data were collected.

Results

Fifty‐five percent of owners had previous knowledge of laparoscopy. Ninety‐two percent of owners would choose laparoscopy over an open procedure for their pet. Reasons given for preferring laparoscopy: less postoperative pain (66.3%), shorter length of hospitalization (26.1%), better cosmesis (20.1%), perception of lower cost (15.2%), faster return to function (14.1%), length of anesthesia (5.4%), and other reasons (26.1%). Ninety‐one percent of owners were willing to pay more for MIS. Among owners who indicated they would be willing to pay more, owners presenting with dogs were 2.5 times more likely to be willing to pay at least $1000 more than owners presenting with cats.

Conclusion

The majority of owners surveyed at a large hybrid hospital in an urban setting choose laparoscopic over open procedures and were willing to pay more for them.

Clinical significance

The results highlight the importance of client and veterinarian education regarding the options of MIS for pets, as owners who are informed may prefer referral for the procedures. The financial investment to build a MIS practice may be justified.
Using Smartphones for Clinical Assessment in Cervical Spondylotic Myelopathy a Feasibility Study
Authors: Zaldivar-Jolissaint Julien Francisco , Lechanoine François , Krummenacher Bernard , Arruda Rivus Ferreira , Bobinski Lukas , Schlichting Emmanuel de , Duff John Michael
Published: October 2021

Degenerative cervical myelopathy (DCM) is characterized by a progressive deterioration in spinal cord function. Its evaluation requires subjective clinical examination with wide interobserver variability. Objective quantification of spinal cord function remains imprecise, even though validated myelopathy-grading scales have emerged and are now widely used. We created a Smartphone Application, the N-Outcome App, with the aim of quantifying accurately and reliably spinal cord dysfunction using a 5-minute Test. A patient suffering from DCM was clinically evaluated before surgery, at 3 and 6 months follow-up after surgical decompression of the cervical spinal cord. Standard scores (Nurick grade, modified Japanese Orthopedic Association (mJOA) score) were documented at these time points. A 5-minute motor and proprioceptive performance test aided by a smartphone with the N-outcome App was also performed. Motor performance in rapid alternating movements and finger tapping improved in correlation with improvements in standard grading scale scores. Clinical improvements were seen in maximum reflex acceleration and in Romberg testing which showed less closed/open eyes variation, suggesting pyramidal and proprioceptive function recovery. We demonstrate that using the N-Outcome App as an adjunct to clinical evaluation of compressive myelopathy is feasible and potentially useful. The results correlate with the results of clinical assessment obtained by standard validated myelopathy scores.
A Numerical and Experimental Study of the Time-Averaged and Transient Flow Downstream of a Butterfly Valve
Authors: Tao Junyu , Lin Zhe , Zhang Guang , Su Jingpan , Zhu Zuchao
Published: October 2021

This research took the DN50 butterfly valve as the research object and studied the flow situation of butterfly valves with different shafts. The resistance characteristics, flow state, characteristics, and flow instability of butterfly valves with different structures were studied by experiments and numerical simulations. Research shows that the flow separation occurs at the edge of the valve disk, and the drag of the valve disk fluctuates nonperiodically with time. Under different opening degrees, the velocity distribution downstream of the valve varies, and the effect of the shaft on the velocity fluctuation is different. Finally, the unstable region of flow downstream of the valve is determined. This study provides a reference for the use and optimization of butterfly valves.
Effects of Different Friction Coefficients on Input Torque Distribution in the Bolt Tightening Process Based on the Energy Method
Authors: Jiang Kai , Liu Zhifeng , Wang Yida , Tian Yang , Zhang Caixia , Zhang Tao
Published: October 2021

Bolted joints are one of the most common fastening methods in engineering applications. To meet the requirements of structural parts, the torque method is often used for controlling the bolted joint performance. However, only a few investigations have been carried out on the conversion efficiency of bolt torque to the tensile force, leading to uncertainty and potential safety hazards during the bolt tightening. In order to study the input torque distribution and overcome problems caused by the Motosh method and experimental investigations, a new energy-based torque distribution model is established in the present study. In the proposed model, numerous affecting parameters, including the connector compression work, effective bearing radius, effective thread contact radius, and spiral angle are considered. Then a parameterized thread mesh model using finite element technology is proposed to analyze the influence of different bolt friction coefficients on the bolt tightening process. Based on 16 types of tightening analyses, it is concluded that as bolt friction coefficient increases, the corresponding torque conversion rate decreases from 14.45% to 7.89%. Compared with the Motosh method, the torque conversion rate obtained by the proposed method is relatively large, which makes the actual pre-tightening force larger than the design value. However, there is still a possibility of bolt failure.
Effects of Wing Kinematics on Modulating Odor Plume Structures in the Odor Tracking Flight of Fruit Flies
Authors: Lei Menglong , Li Chengyu
Published: October 2021

Insects rely on their olfactory system to forage, prey, and mate. They can sense odorant plumes emitted from sources of their interests with their bilateral odorant antennae, and track down odor sources using their highly efficient flapping-wing mechanism. The odor-tracking process typically consists of two distinct behaviors: surging upwind and zigzagging crosswind. Despite the extensive numerical and experimental studies on the flying trajectories and wing flapping kinematics during odor tracking flight, we have limited understanding of how the flying trajectories and flapping wings modulate odor plume structures. In this study, a fully coupled three-way numerical solver is developed, which solves the 3D Navier-Stokes equations coupled with equations of motion for the passive flapping wings, and the odorant convection-diffusion equation. This numerical solver is applied to investigate the unsteady flow field and the odorant transport phenomena of a fruit fly model in both surging upwind and zigzagging crosswind cases. The unsteady flow generated by flapping wings perturbs the odor plume structure and significantly impacts the odor intensity at the olfactory receptors (i.e., antennae). During zigzagging crosswind flight, the differences in odor perception time and peak odor intensity at the receptors potentially help create stereo odorant mapping to track odor source. Our simulation results will provide new insights into the mechanism of how fruit flies perceive odor landscape and inspire the future design of odor-guided micro aerial vehicles (MAVs) for surveillance and detection missions.
Numerical Analysis on the Flow Bifurcation and Heat Transfer Regulation in the Constricted Cavity Under the Transverse Magnetic Field Using OpenFOAM
Authors: Singh Ranjit J. , Gohil Trushar B.
Published: October 2021

In this study, the heat transfer pattern and flow bifurcation in the fluid is observed by the application of low intensity magnetic field in the gradually constricted cavity. The natural convection flow solver with Lorentz force and Boussinesq approximation as a source term is developed in the open-source CFD platform OpenFOAM. The Lorentz force in the flow is altered by varying the Hartmann number of Ha = 0 – 100, however the buoyancy force is kept constant in the flow at fixed Rayleigh number of Ra = 106. The orientation of magnetic field is exposed to be in the y-direction (By). The significance of using the By magnetic field with its various intensity in the constricted enclosure on the heat transfer and flow pattern is reported. It is perceived that the transverse magnetic field (By) and its varying intensity regulates the heat transfer with multiple convection rings. The detail study on the isotherms, streamlines, and the time average Nusselt number is reported.
CFD Analysis of Refrigeration Cycle Ejector
Authors: Forster Franz X. , Deravanessian Alexander E. , Nazarian Matthew J. , Rubio Mariano , Anderson Kevin R.
Published: October 2021

The use of ejector cycles for increased performance and efficiency is becoming more prevalent in industry. The goal of this study is to evaluate an ejector using Computational Fluid Dynamics (CFD) to evaluate flow patterns, perform trade studies varying the type of refrigerant, and determine the entrainment ratio for each working fluid, over a range of boundary condition pressures, set at points along the ejector’s flow path. The 2012 Toyota Prius V is one of the first automobiles using an ejector cycle in their internal cabin refrigeration system. The DENSO Corporation ejector hardware was used as the basis for the creation of geometry for the CFD mode of the ejector. Three working fluids were simulated, R-134a, R-245fa, and R-1235yf. The primary findings of this study were as follows. The CFD study here indicates that R-245fa performs the best out of the three working fluids, when examining their entrainment ratios (ratio of secondary to primary flow rates in the ejector). For all three working fluids, the entrainment ratio was seen to peak performance at an ejector inlet pressure of 1.75 × 105 Pa. The ejector mixing chamber pressure and ejector outlet pressure boundary conditions also witnessed a rise in entrainment ratios, during an increase of their respective pressure values.
Teaching Limiting Behavior of Plane Oblique Shocks
Authors: Farokhi S. , Taghavi R.
Published: October 2021

Plane oblique shocks are formed in supersonic flows that cause abrupt flow deceleration, compression and turning. This behavior persists up to a maximum flow turning angle, θmax and a corresponding shock angle βmax for any upstream Mach number M1 with corresponding Mach angle, μ1. Beyond the maximum turning angle, the oblique shock becomes detached from the body and forms a bow shock. In teaching limiting behavior of plane oblique shocks, over a broad Mach range, from 1.5 to 5.0, we discover two interesting correlations. The first is on βmax which remains nearly invariant and the second is (μ1 + θmax) that remains nearly constant. In air with γ = 1.4, βmax is nearly 65.64° with 0.67° standard deviation and (μ1 + θmax) is nearly 53.24° with 0.32° standard deviation angle. Rankine-Hugoniot and Prandtl oblique shock relations are used in theoretical demonstrations of limiting behavior of plane oblique shocks.
Behavior of Cell Under Wall Shear Stress in Flow Field: Comparison Among Cell Types
Authors: Hashimoto Shigehiro , Yoshinaka Kiyoshi , Yonezawa Hiroki
Published: October 2021

Does the hysteresis effect remain in each cell after division? In the present study, the cell activity has been investigated after division under a shear stress field. To apply the constant shear stress field on cells, a Couette type flow device has been manufactured: between parallel walls (a lower stationary culture disk, and an upper rotating disk) with a constant gap. The wall shear stress was controlled by the rotating speed of the upper disk. Four types of cells were used in the test: C2C12 (mouse myoblast cell line), HUVEC (Human Umbilical Vein Endothelial Cells), 3T3-L1 (mouse fat precursor cells), and L929 (mouse fibroblast connective tissue). After cultivation without flow for 24 hours for adhesion of cells on the lower plate, the shear stress of 1 Pa was continuously applied on cells for 7 days at 310 K. The behavior (alignment and deformation) of each cell was traced at the time lapse image observed by an inverted phase contrast microscope placed in an incubator. The experimental results show the following behavior of each type of cell: C2C12 tends to return to the same direction as that of before division. Deformed 3T3-L1 tends to tilt to the flow direction.
Machine Learning Approach to Predict Sand Transport in Horizontal and Inclined Flow
Authors: Vieira R. E. , Xu B. , Karimi S. , Shirazi S. A.
Published: October 2021

Model predictions are routinely used to help in the decision-making process. For instance, in the oil and gas industry, the accumulation of solid particles, such as sand, and the formation of a bed of solids at the bottom of the pipe can be consequential. Such accumulation may decrease the efficiency of the pipeline due to the increase in the frictional pressure loss; increase the risk of pipeline damage due to erosion; or increase the possibility of pipeline corrosion damage under the bed of solids. In order to transport the solid particles in the pipe, the fluid velocity must exceed the critical velocity required for solid particle transport. Mechanistic models are used to provide a reasonable estimate for the critical velocity needed to transport the particles. However, those models are commonly applicable in their respective ranges of data fitting; and are limited by the applicability of the empirically based closure relations that are a part of such models. On the other hand, the accumulation of experimental data makes possible the application of data-driven methods for characterizing multiphase flow for a broader range of flow conditions. This paper presents a framework to predict the fluid velocity needed to transport solid particles in a pipeline via machine learning (ML) approach. In order to prepare a dataset for training ML models, the critical velocity data are collected from available sources in literature. With the purpose of decreasing the number of input parameters for ML algorithms and to make the model similar for different types of carrying fluids, a set of dimensionless variables has been used. To create the predictive models, three ML algorithms are applied: Random Forest, Support Vector Machine, and Gradient Boosting. The fine-tuned models are compared using statistical analysis to identify the ones that provide the most accurate velocity predictions for different operating conditions. Moreover, the predictive abilities of the models are further validated by comparing their performance with different mechanistic models. The proposed ML approach demonstrates high accuracy in predicting critical velocity across a wide range of flow conditions and inclination angles.
Three-Dimensional Weighted Multiple-Relaxation-Time Pseudopotential Lattice Boltzmann Method for Multiphase Flow
Authors: Tang Jun , Zhang Shengyuan , Wu Huiying
Published: October 2021

The pseudopotential lattice Boltzmann (LB) method has been widely used for simulating multiphase flow due to its concise concept and computational simplicity. In this paper, based on the weighted orthogonal transformation matrix, a three-dimensional (3D) weighted multiple-relaxation-time pseudopotential lattice Boltzmann method (WRMT-LBM) is developed, in which the standard lattice stencil D3Q19 is adopted. Compared with the classical multiple-relaxation-time pseudopotential lattice Boltzmann method (CMRT-LBM) based on the orthogonal transformation matrix, the expressions of the equilibrium density distribution function and discrete force term in moment space are simplified in the present model, which contributes to simplifying the program implementation and improving the computational efficiency. Moreover, an additional discrete source term in moment space compatible with the proposed model is introduced to achieve tunable surface tension. A series of numerical tests are then implemented to investigate the performance of the proposed model. Compared with the CMRT-LBM, the results of the present model can achieve lower spurious velocity and higher computational efficiency while keeping comparable accuracy. Furthermore, using the present model, three benchmark cases, including droplet oscillation, droplet impacting on wall and droplet impact on thin film, are performed to investigate the performance of this model. The numerical results are in good agreement with the analytical solutions or the empirical correlations in the literature, which demonstrates that the present model can simulate the multiphase flow with large density ratio.
Study on Overall Design of a Vertical Take-Off and Landing Unmanned Aerial Vehicle Powered by Electric Ducted Fans
Authors: Chou Tawei , Ying Qiyu , Qian Yuping , Zhuge Weilin , Zhang Yangjun
Published: October 2021

Facing the growing traffic fleet in the cities nowadays, it is believed that three-dimensional urban transportation could be a solution and will be introduced in the near future. Vertical take-off and landing flying platforms powered by ducted fans will attract increasingly attention because it has advantages on high propulsion efficiency, low noise, and better safety. However, unlike traditional open-blade multi-rotor drones, ducted fan drones lack a systematic design approach that comprehensively considers the overall system performance and the power unit efficiency. Current design procedure leads to insufficient load capacity and low efficiency systems. This paper proposes an overall design method for a ducted fan-type vertical take-off and landing flight platform. The ducted fan and motor of the core power unit are designed and selected aiming at improving aerodynamic efficiency and structural utilization of the system. A heavy-load vertical take-off and landing Unmanned Aerial Vehicle (UAV) powered by ducted fans with a take-off weight of 450kg is designed based on this method. CFD simulation is utilized to calculate the performance of the designed Unmanned Aerial Vehicle, and finite element analysis is carried out to examine the overall strength safety. The final design results show that the overall design method plays a great role in the development of ducted fan UAV.
Investigation of Tool-Joint Effect on Non-Newtonian Drilling Fluids Following the Herschel–Bulkley Model Flow Behavior in Oil Well Drilling
Authors: Gholami Ardeshir , Mansoori Zohreh , Saffar Aval Majid , Ahmadi Goodarz
Published: October 2021

The prediction of frictional pressure loss in many oil wells drillings is of the utmost importance. Most studies in this area concerned fluid flow in pipes and annulus in order to predict friction losses. However, studies on the tool-joint effect in frictional pressure estimations were limited to only a few experimental and theoretical studies on water-based power-law drilling muds. (Tool-joint is the part in which two drill strings connect where the annulus has a gradual decrease and increase, respectively). The tool-joint plays an important role in extending the drill pipe, and its effect on pressure losses cannot be ignored. As of today, drilling muds must have certain qualities such as providing formation integrity, transporting the cuttings from bit to surface, drill pipe lubrication and heat transfer, and low-pressure loss to perform as a qualified and effective drilling fluid. Therefore, drilling muds have become more complex and expensive, and the process of choosing appropriate drilling muds is of great importance. For this reason, oil-based viscoplastic drilling muds are being used in more drilling operations, but for these drilling muds, almost no studies were conducted to predict the effect of the tool-joints on flow behavior and pressure loss.

In this paper, the behavior of fluid flows and frictional pressure losses in weld-on tool-joints of different grades according to the IADC standard manual was studied using CFD simulations. The simulations were conducted using a drilling fluid with viscoplastic properties, following the Herschel–Bulkley model of Non-Newtonian fluids. And the characteristics of fluid flows in these tool-joints under different thermal boundary conditions were studied. The results show that tool-joints significantly affect the frictional pressure loss in the annulus. We also provided an accurate pressure loss prediction for the flow of oil-based viscoplastic muds passing through the tool-joint geometry. Furthermore, assuming the thixotropic behavior using the Moore-Cheng model for the drilling mud, the results showed that the flow behavior does not differ significantly from the Herschel-Bulkley drilling fluid in the range of study.
An Improved Level-Set-Based Immersed Boundary Reconstruction Method for Computing Bio-Inspired Underwater Propulsion
Authors: Pan Yu , Dong Haibo , Zhang Wei
Published: October 2021

The immersed boundary method (IBM) has been widely employed to study bio-inspired underwater propulsion which often involves the high Reynolds number, complex body morphologies and large computational domain. Due to these problems, the immersed boundary (IB) reconstruction can be very costly in a simulation. Based on our previous work, an improved level-set-based immersed boundary method (LS-IBM) has been developed in this paper by introducing the narrow-band technique. Comparing with the previous LS-IBM, the narrowband level-set-based immersed boundary method (NBLS-IBM) is only required to propagate the level set values from the points near the boundaries to all the points in the narrow band. This improvement reduces the computational cost from O((LD/Δx)3) to O(k(LD/Δx)2). By simulating a steady-swimming Jackfish-like body, the consistency and stability of the new reconstruction method in the flow solver have been verified. Applications to a dolphin-like body swimming and a shark-like body swimming are used to demonstrate the efficiency and accuracy of the NBLS-IBM. The time for reconstructions shows that the reconstruction efficiency can increase up to 64.6% by using the NBLS-IBM while keeping the accuracy and robustness of the original LS-IBM. The vortex wake of the shark-like body in steady swimming shows the robustness, fastness and compatibility of the NBLS-IBM to our current flow solver.
The Effect of Membrane Topology on Separation Performance of Vacuum Membrane Distillation Module
Authors: Caspar Justin , Xue Guanyang , Krysko Robert , Oztekin Alparslan
Published: October 2021

Computational fluid dynamics simulations were conducted to evaluate the effect of a wavy channel in a two-dimensional vacuum membrane distillation module. The curvature was induced using a sinusoidal profile along the membrane and bottom wall. Contour plots and line profiles provide a detailed view of the flow structure and the effect of the proposed configuration on the flux performance. Module averaged temperatures, concentrations, and flux values were calculated for two selected Reynolds numbers. Results indicate that at low Reynolds numbers, the wiggly module performs worse than the flat sheet module. Due to the channel’s curvature changing the direction of the bulk flow and the absence of secondary flows to promote mixing, the thermal boundary layer along the membrane surface can be more intense versus a flat sheet membrane, causing more intense temperature polarization and reduced flux performance. At Reynolds number 500, there was a 5% decrease in the flux for the curved versus flat case. However, in some curved channel areas, the local performance was superior to the flat channel. Increasing the Reynolds number could aid the performance of the wiggly channel immensely.
Digital Assignments for Thermo-Fluids Courses
Authors: Milanovic Ivana , Eppes Tom A. , Goparaju Kalyan
Published: October 2021

Simulations were used in lecture-based courses, Thermodynamics I and Thermodynamics II, for demonstration purposes and as digital assignments. Digital assignments were separate from the customary pencil & paper homework given once a week. The primary objective was to model the flow and heat transfer in a system, reinforce theoretical concepts, and allow study of more complex two- and three-dimensional problems.

Students encounter fluid flow and heat transfer in the sophomore course, Thermodynamics I, for the first time. Velocity, pressure and temperature fields are quite complicated even for simple geometries, hard to visualize, and difficult to understand. Digital assignments go beyond basic theoretical concepts and relatively simple pencil & paper problems. Initially, there were 6 digital assignments in each course. After the first offerings and assessments, the number of assignments is expected to grow to 8–10. Scaffolding of digital assignments ensured that simulations gain in complexity as students become more familiar with both the theoretical underpinnings and the software interface.

Our Mechanical Engineering program, has a freshmen graphic communication course incorporating AutoCAD and a junior CAD course with SolidWorks and Ansys. This provided both a challenge and an opportunity for lecture-based thermo-fluids courses positioned ‘in between.’ Modern computational skills were obtained outside the classroom, and that was accomplished with effective use of an on-line environment. Ansys Fluent was chosen to present and reinforce thermo-fluids fundamentals. Each digital assignment had a mesh, detailed grading criteria, and supplementary documentation. Students worked on the: (1) problem set up in the preprocessor-stage, (2) solver, and (3) postprocessor. This approach helped students (1) understand the flow and heat transfer inside the system as well as the application of conservation of mass and energy, (2) understand and interpret results by comparing them with theoretical and experimental data, (3) develop modern technical skills relevant to the demands of Industry 4.0, and (4) develop research capabilities.

Simulations in the classroom and as digital assignments are a representation of the real world, and provide an egalitarian and unrestricted way for students to interact with it, acquiring skills and an appreciation for subject matter as well as the engineering profession. Semester long discussions on various aspects of digital assignments help develop a mentor-mentee bond. This approach to teaching, research and mentoring does not depend on access to laboratory facilities and funding that can reach only a limited number of students. It encourages students’ spirit of inquiry, and ultimately leads to a professional development opportunities beyond the classroom setting.
Hysteresis Effect of Tangential Force Field With Centrifuge on Myoblast: Cultured on Striped Pattern of Micro Ridge for Direction Control
Authors: Hashimoto Shigehiro
Published: October 2021

Hysteresis effects of the direction of mechanical stimulation on the cell behavior have been examined in vitro. A micro ridge pattern was made on the surface of the scaffold to align the directions of the cells being stimulated. The stripe pattern (0.7 μm heigh, 3 μm wide, and 3 μm interval) was created by the photolithography technique. Three regions, which have the uniform value of the angle between the longitudinal direction of the ridge and the direction of the tangential force, were set: 0, 45, and 90 degrees in each region. Myoblasts (C2C12: mouse myoblast cell line) were used in the experiment. The scaffold plate with cells was set in the tube of a conventional centrifuge placed in an incubator to apply the tangential force field to each cell. After the cell culture for 5 hours with centrifugation, the behavior of each cell was analyzed on time-lapse microscopic images for 10 hours. Experimental results show that cell activities (migration and deformation) are enhanced after stimulation of tangential forces perpendicular to the long axis of myoblasts.
A Unified Theory for the Pressure Change of Sudden Expansions and Contractions Based on the Momentum Balance
Authors: Müller Sebastian , Malcherek Andreas
Published: October 2021

In this paper a unified approach based on the momentum balance is presented, capable of predicting the pressure change of sudden contractions and sudden expansions. The use of empirically determined correction coefficients is not necessary. Therefore, the momentum balance is derived similarly for both applications but with different control volumes. The control volume takes into account the specific geometry of the hydraulic structure. With a properly chosen control volume, the unified approach requires coefficients that account for the velocity as well as pressure distributions on the boundaries of the control volume. These coefficients can be obtained by parameterizing the results of numerical simulations by simple analytical functions. The numerical model itself is validated by checking the simulated pressure change against calculated or measured pressure changes. It is found that the formulation of the momentum balance for the sudden expansion is more complex compared with the sudden contraction. The prediction of the pressure change of flows through sudden expansions can be improved by applying the momentum balance non-idealized. Most of the correction coefficients originate from an inappropriate application of Bernoulli’s energy conservation principle. Consequently, this leads to a gap between theory and experimental results. The proposed unified approach solely contains physical coefficients that are used to substitute integrals by averaged expressions.
Large Eddy Simulations of a Turbocharger Radial Turbine Under Pulsating Flow Conditions
Authors: Mosca Roberto , Lim Shyang Maw , Mihaescu Mihai
Published: October 2021

The pulsating flow conditions which a turbocharger turbine is exposed cause important deviations of the turbine aerodynamic performance when compared to steady flow conditions. Indeed, the secondary flows developing in the turbine are determined by the inflow aerodynamic conditions, which largely vary during the pulse cycle.

In this paper, a high-resolved Large Eddy Simulation is performed to investigate and characterize the flow field evolution in a turbocharger radial turbine over the pulse cycle. At first, the model is validated against experimental results obtained in gas-stand flow conditions. Then, the instantaneous flow field at the rotor mid-span section is compared to the one given by the equivalent cycle-averaged steady flow conditions. The results highlight five distinct flow features. At low mass flow rates, when the relative inflow angle assumes large negative values, the flow separates at the blade pressure side, causing a secondary flow consisting in two counter-rotating vortices characterized by a diameter comparable to the blade passage. As the mass flow rate increases, the first vortex persists at the blade tip while the second one moves closer to the blade trailing edge. This corresponds to the second characteristic flow field. With increasing relative inflow angle, for the third characteristic flow feature, only the recirculation at the blade leading edge is displayed and its size gradually reduces. For the fourth characteristic flow feature, at moderate negative values of the relative inflow angle, the flow field is well aligned with the blade profile and free of secondary flows. Then, as the relative inflow angle gradually grows towards large positive values, the flow separates on the blade suction side causing the mixing of the flow with the stream flowing on the pressure side of the previous blade.
Influence of Exposed Electrode Thickness on Plasma Actuators Performance for Coupled Deicing and Flow Control Applications
Authors: Rodrigues F. F. , Abdollahzadeh M. , Pascoa J. , Pires L.
Published: October 2021

Dielectric Barrier Discharge (DBD) plasma actuators are a popular topic of research within the active flow control field. Recently, these devices have gained interest for deicing and ice prevention applications and it has been proved they allow to perform simultaneously deicing and flow control. Studies have shown that the exposed electrode plays an important role on the surface temperature field of the plasma actuator. Thus, in the current study, by the first time, we investigate the influence of the exposed electrode thickness on the induced velocity flow field and surface temperature field. Three plasma actuators with different dielectric thicknesses (0.3 mm, 0.6 mm and 1.02 mm) were mounted with a thick exposed electrode (thickness of 0.8 mm). These three actuators with thick exposed electrode were experimentally studied and compared against other three plasma actuators with same dielectric thickness but with a thin exposed electrode (thickness of 80 μm). The DBD actuators were experimentally studied considering their electrical, mechanical and thermal behavior. The results are presented and discussed in order to understand the influence of the exposed electrode thickness on the mechanical and thermal plasma actuator performances.
Analysis and Implementation of Dielectric Barrier Discharge Plasma Actuators for Ground Vehicles Wake Reduction
Authors: Rodrigues F. F. , Moreira M. , Pascoa J.
Published: October 2021

Plasma actuators are promising devices with several possible applications in active flow control field. One of the possible applications of these devices is wake reduction in ground vehicles. By delaying the flow separation and reducing the wake of the flow, these devices allow to reduce the drag which, in turns, leads to important savings in terms of fuel consumption. In the current work, the operation of dielectric barrier discharge plasma actuators is studied considering their application for active flow control in ground vehicles. A plasma actuator was fabricated and experimentally characterized in terms of electrical and mechanical features. A ground vehicle model, with different rear slant angles, was constructed and preliminary tests were performed in a wind tunnel. The dielectric barrier discharge plasma actuator was implemented on the top rear part of the model, in the first separation zone of the flow, in order to attach the flow to the surface and reduce the wake flow. The experimental tests were performed for rear slant angles of 30°, 45° and 60°. The different vehicle models were tested for a flow velocity of 5m/s. Flow visualization and velocity measurements were performed in order to analyze the flow behavior and the active flow control effect obtained by the plasma actuation. It is shown that by using plasma actuators on the rear of the model, the plasma actuation pulls the flow toward the surface and reduce the wake of the flow.
A Novel Mathematical Framework for the Venous Valve Leaflet Morphology Extracted From In-Vitro Images Using Machine Learning Assisted Stereological Analysis
Authors: Kotteda V. M. Krushnarao , Janssen Herb F. , Harris Christopher , Kumar Vinod
Published: October 2021

It has been suggested that stasis (stagnant zones over a period of time, dependent on other factors such as age, or underlying medical conditions, such as cancer or covid19) in the valve pockets may increase the risk of clots due to stasis in combination with other factors increases the risk of Deep Venous Thrombosis (DVT) formation, blood stasis may also result in a decrease in the anticoagulants factors that prevent clots from forming, and if the vein wall is damaged this further increases the risk of clot formation. We propose a proactive framework to predict DVT vulnerability, track progression and provide patient care checkpoints is of clear benefit. The framework is based on leading-edge cloud computing technologies and promises to offer user-friendly Software- & Platform-as-a-Service (SaaS/PaaS) solutions via novel machine learning (ML) algorithm and high fidelity blood flow modeling through the venous network under various valve configurations. In this work, we will present the progress made towards the leaflet morphology extraction from in-vitro images using ML assisted stereological analysis for obtaining a sufficiently accurate representation of morphology. Ultimately, the workflow can be tailored to specific patients. The extracted valve is used to identify red-flag stagnant zones by a detailed, physics-based computational study of the blood flow through the leaflet models.