bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of the Accuracy and Safety of TiRobot‐Assisted and Fluoroscopy‐Assisted Percutaneous Pedicle Screw Placement for the Treatment of Thoracolumbar Fractures
Authors: Lin Shu , Wang Fei , Hu Jiang , Tang Liu‐yi
Published: September 2022

Objective

Studies have compared the safety and accuracy of robot‐assisted techniques for inserting conventional open pedicle screws for spinal surgery. However, no relevant studies have confirmed that robot‐assisted percutaneous screw placement is better than fluoroscopic percutaneous screw placement for the treatment of thoracolumbar fractures. This study compared the accuracy and safety of TiRobot‐assisted percutaneous pedicle screw placement with those of the fluoroscopy‐assisted percutaneous technique for the treatment of thoracolumbar fractures.

Methods

This retrospective study included 126 patients with thoracolumbar fractures who underwent percutaneous pedicle screw placement. Sixty‐five patients were treated with the TiRobot‐assisted technique and 61 patients were treated with the fluoroscopy‐assisted technique. Patient demographics, accuracy of screw placement (according to the Gertzbein and Robbins scale of grades A to E), screw insertion angle, radiation exposure, surgical time, intraoperative blood loss, length of hospital stay, incision length, hospital expenses, surgical site infection, and neurological injury of the TiRobot‐assisted and fluoroscopy‐assisted groups were compared using Student's t‐test, Pearson χ2 test, or Fisher's exact test.

Results

A total of 729 screws were placed (TiRobot‐assisted group: 374 screws; fluoroscopy‐assisted group: 355 screws). In the TiRobot‐assisted group, 82.8% of screws were optimally positioned (grade A); however, the placement grades of the remaining screws were categorized as grade B (13.3%), grade C (3.2%), and grade D (0.5%). In the fluoroscopy‐assisted group, 66.7% of the screws were optimally positioned (grade A); however, the placement grades of the remaining screws were categorized as grade B (21.4%), grade C (7.6%), grade D (3.6%), and grade E (0.5%). The proportion of clinically acceptable screws (grade A or B) was greater in the TiRobot‐assisted group than in the fluoroscopy‐assisted group. Additionally, the TiRobot‐assisted group had a significantly larger mean screw insertion angle (22.27° ± 5.48° vs 20.55° ± 5.15°), larger incision length (13.86 ± 1.24 cm vs 12.77 ± 1.43 cm), and higher hospital expenses (69061.55 ± 7166.60 yuan vs 59383.85 ± 5019.64 yuan) than the fluoroscopy‐assisted group. There were no significant differences in the intraoperative blood loss, length of hospital stay, and rates of surgical site infection and neurological injury in both groups (p > 0.05). However, the TiRobot‐assisted group had significantly better surgical times, radiation times, and radiation exposure than the fluoroscopy‐assisted group (p < 0.05).

Conclusions

Percutaneous TiRobot‐assisted pedicle screw placement is a safe, useful, and potentially more accurate alternative to the percutaneous fluoroscopy‐assisted technique for treating thoracolumbar fractures.
Factors associated with immediate and early extubation in pediatric living‐donor liver transplant recipients
Authors: Saeyup Pipat , Paarporn Paweena , Prasarnphan Daraneenuch , Wongpiyaboworn Wasipon
Published: September 2022

Background

The practice of prompt extubation after adult liver transplantation has increasingly been applied in the pediatric population. Therefore, the factors contributing to this intervention should be identified in order to minimize failures.

Aims

We sought to determine the factors associated with immediate and early extubation in pediatric living‐donor liver transplant recipients.

Methods

The medical records of pediatric liver transplant recipients at our center from January 2013 to December 2021, a 9‐year period, were retrospectively collected and divided into early or delayed extubation groups. Factors associated with early extubation were determined using univariate and multivariate analyses, as the primary outcome. Comparisons of the postoperative management and outcomes between groups were evaluated as secondary outcomes.

Results

Seventy‐nine patients were included in the analysis, of whom 19 (24%) were immediately extubated in the operating room while 12 patients (15%) were extubated early, within 24 h postoperatively. These 31 patients (39%) were assigned to the early extubation group, whereas the others were assigned to the delayed extubation group. Shorter anhepatic time was the only factor associated with early extubation (adjusted odds ratio = 0.52; 95% confidence interval: 0.30, 0.89 per 30‐min increment; p‐value = .018) in patients with the same characteristics, including diagnosis, total operative time, and intraoperative volume of albumin and packed red blood cells. The length of intensive care unit stay was shorter in the early extubation group than in the delayed extubation group (p = .001). The rates of total and early medical complications and total reintubation in 30 days were significantly higher in the delayed extubation group than in the early extubation group (p‐value = .002, .044, and .006 respectively). There were no significant differences in the length of hospital stay between the groups.

Conclusion

Our findings indicated that 39% of the pediatric living donor–liver transplantation patients tolerated early extubation and that the only associated factor was anhepatic time. Early extubation significantly reduces the number of days of intensive care unit stay but may not change the length of hospital stay.
Adaptive strategies of Scots pine under shade: Increase in lignin synthesis and ecotypic variation in defense‐related gene expression
Authors: Ranade Sonali Sachin , Seipel George , Gorzsás András , García‐Gil María Rosario
Published: September 2022

Shade is a stressful condition for plants characterized by low Red:Far‐Red (R:FR) ratio. The northern latitudes in Sweden daily receive more hours of FR‐enriched light (twilight) or shade‐like conditions compared to southern forests during the growing season. Scots pine (Pinus sylvestrisL.) is a shade‐intolerant species. Yet, it is well adapted to this latitudinal variation in light, which is evident by a northward increase in FR requirement to maintain growth. Shade adversely affects plant growth; it makes the plant weak and, therefore, susceptible to pathogen attack. Lignin is involved in plant protection against pathogen invasion mainly by forming a physical barrier. We studied lignin synthesis and expression of defense‐related genes (growth‐defense trade‐offs) under a low R:FR (shade) ratio in Scots pine. A higher number of immunity/defense‐related genes were up‐regulated in response to shade in northern populations compared to southern ones, which can be viewed as a local adaptation to light quality for optimal growth and survival. Light quality regulates lignin metabolism; light stimulates lignin synthesis, while shade causes a decrease in lignin synthesis in most angiosperms. In contrast, Scots pine shows an increase in lignin synthesis supported by the higher expression of a few key genes in the lignin biosynthetic pathway, a novel finding reported by our study. These findings can be applied to future breeding strategies in forestry to produce disease‐resilient trees.
Sustaining shifts in science teaching through a research–practice partnership
Authors: Gale Jessica , Koval Jayma , Alemdar Meltem , Grossman Sabrina , Usselman Marion
Published: September 2022

This study examines shifts in science teachers' (N = 15) beliefs and practices within the context of a research–practice partnership (RPP) that developed and implemented curriculum modules in middle school science classrooms. Interview, document, and observation data gathered over the course of the project indicate that the vast majority of teachers intended to continue using the curriculum modules in their classrooms for the foreseeable future. These data also documented potential shifts in teacher attitudes and practices inspired by the modules. Among teacher participants, there were clear examples of teachers modifying other lesson plans to resemble key components of the modules, using module implementation as a context for developing proficiency with inquiry‐oriented teaching, and revisiting or drawing connections to the modules when teaching other science content. The study also documented the typical sequence of shifts in teachers' beliefs and practices, with findings indicating that teacher beliefs were most powerfully influenced by their observations of student performance and engagement during module implementation. By following teachers' beliefs and practices beyond the official implementation timeline of the project, the study lends insight into the ways in which curriculum resources developed in the context of RPPs may have a lasting impact at the classroom level.
A novel HLA‐DQB1*04 variant, HLA‐DQB1*04:90, identified in a Chinese Han individual
Authors: Quan Zhan‐Rou , Zou Hong‐Yan , Zhou Dan
Published: September 2022

Identification of the novel HLA‐DQB1*04:90 allele that differs from DQB1*04:01:01:01 at nucleotide 183 in exon 2 from A to T.
MtING2 encodes an ING domain PHD finger protein which affects Medicago growth, flowering, global patterns of H3K4me3, and gene expression
Authors: Jaudal Mauren , Mayo‐Smith Matthew , Poulet Axel , Whibley Annabel , Peng Yongyan , Zhang Lulu , Thomson Geoffrey , Trimborn Laura , Jacob Yannick , van Wolfswinkel Josien C. , Goldstone David C. , Wen Jiangqi , Mysore Kirankumar S. , Putterill Joanna
Published: September 2022

Flowering of the reference legume Medicago truncatula is promoted by winter cold (vernalization) followed by long‐day photoperiods (VLD) similar to winter annual Arabidopsis. However, Medicago lacks FLC and CO, key regulators of Arabidopsis VLD flowering. Most plants have two INHIBITOR OF GROWTH (ING) genes (ING1 and ING2), encoding proteins with an ING domain with two anti‐parallel alpha‐helices and a plant homeodomain (PHD) finger, but their genetic role has not been previously described. In Medicago, Mting1 gene‐edited mutants developed and flowered normally, but an Mting2‐1 Tnt1 insertion mutant and gene‐edited Mting2 mutants had developmental abnormalities including delayed flowering particularly in VLD, compact architecture, abnormal leaves with extra leaflets but no trichomes, and smaller seeds and barrels. Mting2 mutants had reduced expression of activators of flowering, including the FT‐like gene MtFTa1, and increased expression of the candidate repressor MtTFL1c, consistent with the delayed flowering of the mutant. MtING2 overexpression complemented Mting2‐1, but did not accelerate flowering in wild type. The MtING2 PHD finger bound H3K4me2/3 peptides weakly in vitro, but analysis of gene‐edited mutants indicated that it was dispensable to MtING2 function in wild‐type plants. RNA sequencing experiments indicated that >7000 genes are mis‐expressed in the Mting2‐1 mutant, consistent with its strong mutant phenotypes. Interestingly, ChIP‐seq analysis identified >5000 novel H3K4me3 locations in the genome of Mting2‐1 mutants compared to wild type R108. Overall, our mutant study has uncovered an important physiological role of a plant ING2 gene in development, flowering, and gene expression, which likely involves an epigenetic mechanism.
Spatially uneven pace of deindustrialisation within a country
Authors: Kiyota Kozo
Published: September 2022

The declining share of manufacturing value‐added, often referred to as ‘deindustrialisation’, is fast becoming a major concern for policymakers and academic researchers, especially in high‐income countries. When compared with country‐level analysis, however, regional‐level analyses of deindustrialisation within a country are limited. This paper empirically examines how and why the patterns of deindustrialisation are uneven across regions within a country. The analysis builds upon the neoclassical trade model and uses regional‐level data in Japan where both detailed output and input data are available at the regional and industry levels for both manufacturing and non‐manufacturing industries over the last four decades. One of the major findings is that the large variation in deindustrialisation within a country is attributable to differences in productivity and price changes across regions. In contrast, the effect of the slowdown in capital accumulation, partly from the expansion of foreign direct investment or offshoring, commonly appears not in specific regions but across regions. The effect of spatial interdependence is also not only statistically significant but also nonnegligible in terms of its magnitude.
Sisal wool skin disease in Merino sheep in the Argentine Patagonia region: Identification and molecular diagnosis of Corynebacterium bovis from skin lesions
Authors: Abdala Alejandra Mariana , Farber Marisa , Robles Carlos Alejandro
Published: September 2022

Background

Sisal wool condition is a skin disease affecting Merino sheep in the Argentine Patagonia region. Corynebacterium spp. isolates have previously been isolated from skin swabs from lesions, while specific identification of the bacteria involved has not been reported.

Hypothesis/Objectives

The aim of this work was to characterize the bacterial agent isolated from sisal wool lesions and to develop a diagnostic method for field surveillance.

Materials and Methods

Molecular identification of a collection of 72 isolates obtained previously was performed using PCR and 16S rRNA and rpoB sequencing. A field survey was carried out on two farms in the Río Negro province of Argentine Patagonia. Swab samples from sheep with and without skin lesions were collected and analysed by PCR and culture.

Results

Isolates analysed were confirmed by sequencing as Corynebacterium bovis. Using a PCR test without culture step, all field samples from affected sheep were positive for C. bovis; samples from the healthy skin from the same animals or clinically healthy sheep all were negative.

Conclusions and Clinical Relevance

Sisal wool skin disease was associated with C. bovis infection based on culture and PCR methods; the latter may be useful for helping to pursue a disease control strategy.
Emotional Intelligence and Modes of Conflict Management of Employees of Different Age Groups
Authors: Savio Dominic
Published: September 2022

Business organizations need to sustain their performance in ever increasing volatile business environment. Human Capital is the key to business success. Managing human recourses requires vital knowledge and information on human behaviours. This article presents Emotional Intelligence and Conflict handling behaviour of employees of different age groups. The study was undertaken in automobile and information technology industries in Chennai to measure among the employees the impact of age on emotional intelligence and conflict management. Emotional Quotient Test (Chadha, 2006), Thomas –Kilmann Conflict Mode Instrument (1974) were used for collecting data and statistical tests were used for analysis. Data analysis revealed that employees above 35 years of age had emotional maturity compared with other age groups. In handling conflicts, a pattern emerging from the study was identified: employees below 25 years of age were unassertive, employees between 30 -35 years of age were collaborative and employees above 35 years of age were competing.
Strategies to improve respiratory chemoreflex characterization by Duffin's rebreathing
Authors: Guluzade Nasimi A. , Huggard Joshua D. , Keltz Randi R. , Duffin James , Keir Daniel A.
Published: September 2022

New Findings

What is the central question of this study?

We assessed the test–retest variability of respiratory chemoreflex characterization by Duffin's modified rebreathing method and explored whether signal averaging of repeated trials improves confidence in parameter estimation.

What is the main finding and its importance?

Modified rebreathing is a reproducible method to characterize responses of central and peripheral respiratory chemoreflexes. Signal averaging of multiple repeated tests minimizes within‐ and between‐test variability, improves the confidence of chemoreflex characterization and reduces the minimal change in parameters required to establish an effect. Future experiments that apply this method might benefit from signal averaging to improve its discriminatory effect.

We assessed the test–retest variability of central and peripheral respiratory chemoreflex characterization by Duffin's modified rebreathing method and explored whether signal averaging of repeated trials improves confidence in parameter estimation. Over four laboratory visits, 13 participants (mean ± SD age, 25 ± 5 years) performed six repetitions of modified rebreathing in isoxic–hypoxic conditions [end‐tidal ()  = 50 mmHg] and isoxic–hyperoxic conditions ( = 150 mmHg). End‐tidal (), and minute ventilation (E) were measured breath‐by‐breath, by gas analyser and pneumotachograph. The E versus relationships were fitted with a piecewise model to estimate the ventilatory recruitment threshold (VRT) and the slope above the VRT (ES). Breath‐by‐breath data from the three within‐ and between‐day trials were averaged using two approaches [simple average (fit then average) and ensemble average (average then fit)] and compared with a single‐trial fit. Variability was assessed by intraclass correlation (ICC) and coefficient of variance (CV), and the minimal detectable change was computed for each approach using two independent sets of three trials. Within days, the VRT and ES exhibited excellent test–retest variability in both hyperoxic conditions (VRT: ICC = 0.965, CV = 2.3%; ES: ICC = 0.932, CV = 15.5%) and hypoxic conditions (VRT: ICC = 0.970, CV = 2.9%; ES: ICC = 0.891, CV = 17.2%). Between‐day reproducibility was also excellent (hyperoxia, VRT: ICC = 0.930, CV = 2.2%; ES: ICC = 0.918, CV = 14.2%; and hypoxia, VRT: ICC = 0.940, CV = 3.0%; ES: ICC = 0.880, CV = 18.1%). Compared with a single‐trial fit, there were no differences in VRT or ES using the simple average or ensemble average approaches; however, ensemble averaging reduced the minimal detectable change for ES from 2.95 to 1.39 L min−1 mmHg−1 (hyperoxia) and from 3.64 to 1.82 L min−1 mmHg−1 (hypoxia). Single trials of modified rebreathing are reproducible; however, signal averaging of repeated trials improves confidence in parameter estimation.
E-Designation for Compressible Aerodynamics Course
Authors: Milanovic Ivana , Eppes Tom A. , Goparaju Kalyan
Published: September 2022

The US Air Force has added the ‘e’ designation to denote an aircraft or satellite having been designed using computer modeling and simulation, as well as interface technologies like virtual and augmented reality. This new digital aerospace engineering process, i.e. using computers to design, model, and test aircraft before an actual prototype is built, is so important that it drives the need for a different approach to the engineering curriculum. In response, our students are provided an opportunity to create and analyze throughout a lecture-based course. The availability of sophisticated software and its use outside of the classroom without prior training facilitates nonlinear learning, promotes exploration of alternative resources, from written material to the human network, and ultimately brings it all back to the theoretical underpinnings.

The Compressible Aerodynamics course in its first iteration featured the following simulation projects: (1) Incompressible flow through the converging nozzle, (2) Flying on earth, (3) Pitot tube, (4) Compressible flow over an airfoil, (5) Airfoil in different flow regimes, and (6) Rayleigh flows. They were chosen from six ANSYS Fluids Engineering Innovation Courses that are available free online. Each project originally included a video, handout, and pre-generated mesh, and was further customized with specifically focused grading criteria.

This study built on the authors’ previous work on the use of simulations in the individual courses and course sequences in the mechanical engineering program. The goals were to bring the elements of the new digital aerospace engineering process to standard lecture-based courses, ensure students’ engagement from the beginning, and increase the time students invest in studying. The anticipated challenges (from the perspective of Bloom’s Taxonomy) were (1) non-hierarchal structure of learning where students create and analyze while mastering the use of the tool, (2) integrated and balanced process of learning where every element of the framework is equally important, and (3) the differences that each learner brings, from motivation to the cognitive processing.

The significance of our approach and its success are illustrated with qualitative and quantitative evidence. Qualitative data provide examples of student work, while quantitative assessment of students’ understanding and confidence in comprehension of select concepts includes grades, student surveys, and course evaluations.
The Effect of Phase Interaction Forces and Particle Rotation on Solid Particle Erosion in Liquid-Solid and Liquid-Gas-Solid Flows
Authors: Sedrez Thiana A. , Shirazi Siamack A.
Published: September 2022

Forces acting on both gas and particle phases and the interaction between them and the liquid phase in liquid-gas-solid flow are examined via Computational Fluid Dynamics (CFD) and the results are compared with experimental data. A simplified methodology to simulate multiphase flow is proposed using the Eulerian-Eulerian-Lagrangian approach. The proposed modeling approach for the liquid-gas interaction forces and particle rotation is compared with experimental erosion data for two elbows in series. For the experiments, a 50.8 mm inner diameter pipe vertical facility with water, air, and sand particles is used to collect wall thickness loss data in two elbows in series: one elbow vertical to horizontal and another horizontal to vertical downward. The particle rotation forces in these highly rotational flows with liquid-solid flows are considered in this investigation. In addition, interphase forces between liquid and gas for dispersed-bubble flow, such as drag, surface tension, turbulent dispersion, turbulence interaction, virtual mass, and wall lubrication, were investigated. Lastly, the simulated effect of the forces on fluid velocity, particle velocity, and erosion rates are presented and discussed. The results show that rotation of particles and Magnus lift force do not significantly impact particle trajectory for liquid-solid flows. However, the Magnus lift force exerts an increase in erosion in both elbows. Overall, for liquid-gas-solid flow, interphase forces separately do not significantly impact erosion (presenting on average 24% higher erosion than experimental data). The greater change is observed when drag, virtual mass, wall lubrication, and surface tension are applied together, increasing erosion considerably (83% higher than experimental data).
Experimental and Modeling Study of Sand Transport in Slightly Upward Inclined Solid-Liquid Flow
Authors: Vieira Ronald E. , Shirazi Siamack A.
Published: September 2022

Solid transport in inclined pipes is widely encountered in industrial operations, such as oil and gas production and mining. Understanding the mechanism of solid transport in inclined flow lines has significant importance for the development of these practical applications as well as productivity and safety issues. This paper presents an experimental investigation on the hydraulic transport of solid particles in pipelines in a 5° upward inclined orientation. The pipe had an internal diameter of 2-inch (50.8 mm). Water-solid flows which comprised sand (25–600 μm) and water were tested at solids concentrations between 0.01%–0.5% volume-to-volume ratio (v/v). The tests were carried out by observing the movement of the sand particles in a transparent pipe while regulating the flow rate of the fluid. The critical transport velocity (VC) was determined using video recordings. VC was observed to increase with an increase in sand concentration and sand particle diameter. The critical velocities obtained are compared with results obtained from previous experimental work in inclined and horizontal flow and existing modeling approaches available in the literature.
Effects of Throttling Orifice Plate on Flow and Aerodynamic Noise Characteristics Inside Valve Downstream
Authors: Yu Long-jie , Xiang Fang-na , Hao Jiao-shan , Jiang Yong-bing , Jin Zhi-jiang , Qian Jin-yuan
Published: September 2022

The serious aerodynamic noise is caused in the downstream of control valve by high pressure difference. Severe aerodynamic noise will affect worker safety and production safety. Throttling orifice plate located in control valve downstream is one of the most important devices for reducing aerodynamic noise under high pressure difference. Therefore, studying the effect of throttling orifice plate structure parameters on flow characteristics and aerodynamic noise is of great significance. Based on method of computational fluid dynamics, the inclination angle of conical throttling orifice plate is studied as the research variables. The time-average values of the flow field, pressure and velocity are obtained and evaluated through steady-state RANS. Flow rate is evaluated under condition that the throttling area of the plate remains unchanged. Based on the results of steady-state simulation, the aerodynamic acoustic power level in the whole flow field is obtained through the broadband noise source model. Finally, the influence of the plate inclination angle on the aerodynamic noise is comprehensively evaluated. It is concluded that the downward setting orifice plate (45°) is the best among the all orifice plates. The work has a certain reference value for researching the design of throttling orifice plate and improving aerodynamic noise in downstream of high pressure valve.
Cleaning Effect of Bubbles Impacting Tilted Walls Under Acoustic Waves
Authors: Hooshanginejad Alireza , Sheppard Timothy J. , Manyalla Janeth , Jaicks John , Jung Sunghwan
Published: September 2022

The motion of bubbles near walls is ubiquitous for cleaning purposes in natural and industrial systems. Shear stress induced by bubbles on the surface is used to remove particles or bacteria adhering to the surface. In this study, we investigate the cleaning effect of bubbles on a surface coated with a protein soil solution with and without the presence of an acoustic wave transducer at a single frequency. In addition, we test different drying times for the coated surfaces before conducting the cleaning tests. Our results show that the best bubble cleaning effect occurs for the shortest drying time of the coating and an acoustic wave of 100 Hz.
Wall Roughness Effects on Turbulent Flow Past a Near-Wall Square Cylinder
Authors: Chalmers Heath , Fang Xingjun , Tachie Mark F.
Published: September 2022

Separated turbulent flows induced by two-dimensional square cylinder with different gap heights from a solid wall submerged in a thick turbulent boundary layer are investigated using a time-resolved particle image velocimetry system. Two different upstream wall conditions are implemented to investigate the effects of upstream wall roughness on gap flow. The examined gap ratios between the cylinder and the wall include 0.0, 0.5, and 2.0. The incoming Reynolds number based on the cylinder height and freestream velocity is 12, 750 and the boundary layer thicknesses are 3.6 and 7.2 times the step height, respectively, for the smooth and rough upstream wall conditions. The results are presented in terms of mean flow, Reynolds stresses, and proper orthogonal decomposition. Notably, the wall-roughness effects are most pronounced on the vertical Reynolds stresses and act to reduce the vortex shedding frequency.
Field Predictions of Hypersonic Cones Using Physics-Informed Neural Networks
Authors: Villanueva Daniel , Paez Brandon , Rodriguez Arturo , Chattopadhyay Ashesh , Kotteda V. M. Krushnarao , Baez Rafael , Perez Jose , Terrazas Jose , Kumar Vinod
Published: September 2022

Physics Informed Neural Networks (PINNs) provide a way to apply deep learning to train a network using data and governing differential equations that control the physical behavior of a system. In this text, we propose using the PINNs framework to solve an inverse problem which will discover the partial differential equations for compressible flow from Mach number = 5 by coupling Navier Stokes Equations with a Deep Neural Network (DNN) based on training data generated by a CFD solver. The equations of momentum in 2-dimensions and the equation of energy will be parametrized to let Neural Networks calculate two established learnable parameters. This paper will focus on capturing physics governed by fluid flow phenomena applied to high-speed flows using PINNs, which will allow us to see disturbances such as a shock wave interaction with the free stream. Subsequently, a quantification of the predicted results of PINNs will be carried out, and it will be determined if PINNs are computationally less expensive than the Spectral Element Method codes so widely used.
CFD Analysis of a Grooved Heat Pipe for Space Application
Authors: Hemayet Uddin Salman , Islam Md. , Mone Shital , Jarrar Firas , Fernandes Ryan , Fatt Yap
Published: September 2022

Heat dissipation in space applications is very much necessary. For example, a satellite works under an extreme temperature environment depending on the satellite’s position in the orbit. Apart from thermal energy from the sun, the electronic component in the satellite itself generates heat as well. To maintain the temperature of the components within their operational range, a grooved heat pipe (GHP) is one of the best solutions. Within GHP, capillary action plays a major role to transfer the liquid from the condenser side to the evaporator side under a near-zero gravitational environment.

This paper focuses on the numerical simulation of heat and mass transfer in GHP for space application. The Computational Fluid Dynamics (CFD) simulation is performed using Ansys Fluent software. The omega-shaped axial micro-channelled GHP made from aluminium is considered for this study. The working fluid in the heat pipe is ammonia. The volume-of-fluid (VOF) multiphase model along with the Lee model equation is used to perform the mass transfer prediction. The effects of different heat load for a 25% filling ratio (FR) are studied. This paper mainly focuses on the fluid flow development in the initial 40s of the GHP operation for a specified percentage of FR and heat load.

The CFD simulations give much more insights of the heat and mass transfer phenomena, which would not possible to obtain by experimentation. The results like pressure, velocity, temperature, and volume fraction profiles inside the GHP along the length were studied.
Slurry Pumps Instability Investigation Using High Fidelity CFD Simulation
Authors: Garman Mohamed , Visintainer Robert
Published: September 2022

Slurry pumps are widely used in a variety of applications in the mining, dredging, and aggregate industries. Ensuring stable operation is a major task during pump operation.

In the current study, two slurry pumps are compared which differ only in the design of their casing hydraulics, both using the same exact impeller. The test results showed that a severe instability was formed in the head curve when the smaller casing was used which persisted over a large portion of the curve and resulted in a much lower operating efficiency. changing to the larger casing eliminated the instability and restored the expected pump efficiency. In order to investigate the root cause by examining the underlying flow patterns, a high fidelity, transient, full machine model, including impeller side gap, was developed and applied in a flow range from about 110% to 30% of the pump best efficiency flowrate or QBEP. The CFD simulation results were in good agreement with the measured performances, detecting the instability at the same flow rate for the smaller casing, and no instability when the larger casing is used. Surprisingly, considerable difference between the models appears within the impeller passages, even though its hydraulic design did not change. These differences are characterized, some theories offered regarding the underlying physical effects, and design guidelines proposed for avoiding the undesirable instability in future designs.
Numerical Analysis of Dielectrophoretic-Based DNA Separation and Trapping
Authors: Darabi Jeff
Published: September 2022

In this study, dielectrophoresis (DEP) has been coupled with field-flow fractionation (FFF) for the sorting and trapping of the biological particles. A numerical simulation is performed to compute particle trajectories under the influence of DEP, drag, gravitational, and buoyancy forces, as well as Brownian motion. The simulation was performed using OpenFOAM CFD software. Both positive and negative DEP methods are examined as possible separation techniques for DNA fragments. Positive DEP forces are used to attract the particles to the electrodes and trap them in groups of similar particles while a combination of negative DEP forces and field flow fractionation (FFF) are used to levitate the particles within the fluid flow to certain flow trajectories. The results obtained from this study, including electric field simulations, particle trajectories, elution times, and trapping lengths are presented.
Onto Quantifying Unsteady Propulsion Characteristics Using Momentum and Energy Control Volume Assessments
Authors: Loubimov George , Kinzel Michael
Published: September 2022

This work proposes a novel approach to characterize unsteady, undulating propulsion components through evaluating the momentum and energy equations using detailed control volume analyses. Specifically, it is difficult in such conditions to separate thrust from drag as pressure components are inseparable. In general, the goal is to link physical processes to various components in the control volume assessments that are measurable in detailed computational fluid dynamics (CFD) models. The effort utilizes the Method of Manufactured Solutions (MMS) to verify detailed insight can be extracted from the control volume assessments are developed and indicate that the energy equation uniquely highlights lift-work in the energy budget and separating propulsive and drag forces. The effort expands the findings to previously validated CFD studies studying thrust from heaving and pitching foils; results indicate a novel approach to separate the axial force into thrust and drag components. Overall, the results indicate a promising method useful to separate losses from propulsive mechanisms along with novel metrics of efficiencies useful to measuring self-propelling vehicles.
Experimental Study on Heat Transfer Performance and Flow Pattern in Micro-Fin Tubes and 1EHT Three-Dimensional Heat Exchange Tubes
Authors: Cheng Hong , Gao Yu , Li Wei , Kukulka David John
Published: September 2022

Condensation heat transfer characteristics were studied experimentally using R410A for a mass flow range of 250∼450 kg m-2 s-1 and saturation temperature of 45°C in order to determine the performance of smooth and enhanced heat transfer tubes. Visual flow patterns under condensation conditions were observed in horizontal tubes. Smooth tube condensation flow patterns are consistent with the predicted flow patterns from previous investigations and heat transfer performance in enhanced tubes were compared with the performance found in smooth tubes. The condensation heat transfer enhancement ratio for the enhanced tubes are: 1.15∼2.05 (Vipertex model 1EHT tube), and 1.18∼1.69 for a Helix tube (HX) tube. In addition, the material thermal conductivity of a smooth tube has a small influence on its heat transfer performance; greater enhancement was found in the enhanced tubes. Stratified wavy flow (SW), intermittent flow (I), semi-annular flow (SA) and annular flow (A) were observed in the range evaluated.

The heat transfer coefficient increases with an increase of mass velocity. When the mass flow rate increases, the turbulence of the liquid flow increases and the liquid film becomes thinner. This reduces the thermal resistance and enhances heat transfer; heat transfer performance for low mass velocities rise slowly. The performance improvement at high mass flux rates is greater than that at low mass flux rates. Better heat transfer performance is shown for tube wall materials with high thermal conductivity and/or tubes with smaller diameters.
On the Transition Between Re-Entrant Jet and Condensation Shock Mechanism in Sheet to Cloud Cavitation
Authors: Vaca-Revelo Diego , Gnanaskandan Aswin
Published: September 2022

Sheet to cloud cavitation over a wedge is investigated using numerical simulations performed at a Reynolds number Re = 200,000 and cavitation numbers ranging from σ = 1.44 to σ = 2.18. The multiphase fluid is described using a homogeneous mixture model, and the governing equations are the compressible Navier Stokes equations for the liquid/vapor mixture along with a transport equation for the vapor mass fraction. The numerical method, based on a characteristic based filtering approach for shock and interface capturing, is first validated by comparing with the experimental measurements, showing acceptable agreement. A systematic parametric investigation of sheet to cloud cavitation phenomenon for different cavitation numbers is then carried out. The two primary mechanisms known to destabilize the sheet cavity viz. the re-entrant jet mechanism and the condensation shock mechanism are captured in the simulations. Two cases in the condensation shock regime and two cases in the re-entrant jet regime are investigated in this paper; the similarities and differences between the two regimes are elucidated. The results presented here are part of an ongoing investigation on identifying the precise physical conditions that lead to the transition between the re-entrant jet and condensation shock mechanisms, a clear knowledge of which is yet to be elucidated.
Internal Flow of Sessile Droplets Evaporating on Heated Hydrophobic and Superhydropholic Substrates
Authors: Chen Jingbo , Pan Zhenhai , Wang Zhiguo , Cao Jun , Du Wen , Yu Jialing
Published: September 2022

Evaporation of sessile droplet is a significant common phenomenon. A three-dimensional numerical analysis was carried out to investigate the flow structure inside the sessile evaporating droplet. The present model developed in this study takes buoyancy, vapor diffusion, and evaporation cooling into account. Different flow structures are present inside the droplet evaporating on the hydrophobic and super hydrophobic substrates. On the hydrophobic substrate, the axisymmetric vortex appears in the droplet. The fluid at the bottom of the droplet flows upward along the axis direction, and then flows downward along the droplet surface. On the super hydrophobic substrate, a single non-axis-symmetric vortex is present inside the droplet, the fluid at the bottom of the droplet flows upward along one side of the droplet surface and downward along the other side. The influence of droplet volume and substrate temperature on the flow velocity and temperature distribution inside droplets is discussed quantitatively. The origin of the non-axisymmetric Raleigh convection inside the droplet on the heated superhydrophobic substrate is discussed. We found that the axis-symmetric flow in the droplet is not stable on heated superhydrophobic substrate. Any perturbation in the system can get enlarged and drive the instable axis-symmetric flow turns to a non-axis-symmetric rolling flow.
Separation Control on an NACA 0025 Airfoil Using an Array of MEMS-Based Synthetic Jets
Authors: Xu K. , Lavoie P. , Sullivan P.
Published: September 2022

An novel array of micro-electromechanical systems (MEMS) synthetic jets was designed to control flow separation by periodic blowing at two pre-determined frequencies on a NACA 0025 airfoil for a chord Reynolds number Rec = 105 and angle-of-attach α = 10°. The synthetic jets were generated by commercially available microblowers, providing ease of maintenance compared to other customized synthetic jet actuators. The velocity output of this jet array was characterized with hot-wire anemometry (HWA), and reattached flow was identified using smoke-wire visualization. Pressure measurements show that the array can suppress flow separation on the airfoil, resulting in 2.5 times lift recovery. From wake measurements, up to 50% drag reduction was achieved with the actuation of the jet array compared to the baseline (uncontrolled) case. Particle image velocimetry (PIV) was used to visualize the flow fields of the baseline case and two controlled cases. There was a significant difference in the scale of the vortices produced by the jet array and features of the reattached flow between the two actuation frequencies used.
Turbulent Characteristics of the Wake Flow Around Rectangular and Trapezoidal Prisms in Uniform Flow
Authors: Kang Jinhao , Kumahor Sedem , Sagharichi Amir , Tachie Mark F.
Published: September 2022

The turbulent characteristics of flow separation induced by a trapezoidal and two rectangular prisms immersed in a uniform flow were studied experimentally using particle image velocimetry. The streamwise aspect ratios (AR) of the two rectangular prisms were 3 and 4. The streamwise AR of the trapezoidal prism was based on its upper length and was 3. The Reynolds number based on the freestream velocity and the prism height was 14700. The flow topology of symmetrical wake flows over and behind the rectangular prisms and asymmetrical wake flow over and behind the trapezoidal prism were analyzed using the mean flow and Reynolds stresses. The results indicate that the mean flow reattaches onto the rectangular prisms but does not reattach onto the trapezoidal prism. Dual local regions of elevated streamwise Reynolds normal stress occur in the wake region irrespective of AR and the body geometry. However, the dual elevated regions are only symmetric about the horizontal centerline of two rectangular prisms. Probability density function (PDF), two-point correlations and proper orthogonal decomposition (POD) analyses were employed to investigate the dynamics of the coherent structures formed over and behind the prisms.
Investigations of Aspect Ratio Effects on Wake Dynamics of Rectangular Cylinders
Authors: Liu Manqi , Kumahor Sedem , Audette Lucas , Tachie Mark F.
Published: September 2022

In this paper, the flow characteristics around rectangular cylinders with different length to height ratios (aspect ratios, AR) of AR1, AR2, AR3 and AR4 are studied using a particle image velocimetry. The Reynolds number (Re) was 7200 in all cases and the results were analyzed in terms of the mean flow characteristics, Reynolds stresses and triple velocity correlations. The separated flow did not reattach for AR1 and AR2 cylinders. The flow topology around the AR2 cylinder showed a massive wake vortex compared to the other tested cases. The recovery of the mean velocity within the wake region was slowest for AR2, meanwhile, AR3 and AR4 revealed mean reattachment over the cylinder. The magnitudes of the Reynolds stresses and triple velocity correlations were consistently higher along the cylinder centerline for AR1 compared to the other cases.
Four-Way Coupled Simulation of Proppants Flowing in Rock Fracture With Realistic Geometry- Hydraulic Fracturing Application
Authors: Rousta Farid , Ahmadi Goodarz , Crandall Dustin
Published: September 2022

Four-way coupled Lagrangian-Eulerian proppant-laden flow simulations were performed using different software, including Star CCM+ and the Rocky package coupled with the Ansys-Fluent code. The particular application was focused on the hydraulic fracturing process. The uniformity of the proppant distribution and the total proppants coverage inside the rock fracture define the process efficiency. The desired outcome is a high number of particles trapped uniformly inside the fracture providing high fracture coverage. This study simulated the high-pressure liquid-solid mixture flow and predicated proppants’ transport, displacement, and distribution in rock fractures. A realistic three-dimensional rock fracture geometry was generated using the Brown method. Several pressure gradients were considered, and the four-way coupled proppant-laden flows in fractures with various aperture sizes and lengths were simulated. The effects of proppant size, fluid properties, and fracture characteristics on the final coverage were studied. In addition, different horizontal and vertical fracture configurations were considered. It was shown that the fracture coverage changes dramatically by including a realistic surface roughness compared to a smooth channel fracture model. It was also shown that the ratio of particle diameter to the mean aperture size significantly affects the fracture coverage, and the optimum proppant size for a given aperture was evaluated. The number of trapped proppants inside the fracture was tracked over time from the injection until the steady-state flow was reached, and the number of particles approached a constant value. The final steady-state coverages for different cases were calculated and compared. Finally, the influences of various parameters on the efficiency of the fracturing process were discussed.
Development of Nano- and Micro-Fluids Using Magnetic Poly(Ionic Liquid)-Surfactant Complexes for Stimuli Response
Authors: Foley Kayla , Walters Keisha B.
Published: September 2022

Poly(ionic liquid) (PILs) are a rapidly growing subclass of polyelectrolyte which combines the diverse functionality of ionic liquids with the mechanical integrity, processability, and macromolecular design of polymeric systems. PIL properties are highly dependent on their counterion, which can be easily exchanged to tailor their material properties. Incorporation of metal halide counterions (FeCl4−, CoCl42−, etc.) into the PIL structure results in magnetically responsive metal-salt composites known as magnetic-PILs (MPILs). MPILs are predominately formed through electrostatic binding with anionic metal complexes typically resulting in paramagnetic properties at room temperature. The engineering properties and the ability to effectively apply these materials — is dependent on not only the chemical structure, but the nanostructure, co-materials, self-assembly, and stability in situ. In this study, a PIL copolymer, poly(acrylamide-co-diallyl dimethylammonium chloride), containing a quaternary ammonium PIL group and a comonomer capable of metal coordinating interactions, was combined with sodium dodecyl sulfate surfactant and cobalt (II) chloride salts to form magnetic polyelectrolyte-surfactant complexes. The self-assembly of these complexes was studied as a function of surfactant concentration through DLS, Zeta potential, and TEM characterizations. The magnetic properties were examined using AC susceptibility. The impact of the metal ion(s) and magnetic field on nanostructure alignment and film formation were also investigated through optical microscopy, GISAXS, and AFM imaging. Results were compared to well-defined ferrofluids as a comparative benchmark.
A Numerical Method and Study of Viscoelastic Droplet Breakup
Authors: Anderson Caroline , Kinzel Michael
Published: September 2022

This paper presents a comprehensive study of viscoelastic, droplet-breakup physics using multiphase computational fluids dynamics (CFD) based on the volume of fluid (VOF) method. The specific challenge and novelty are the overall outcome and methods used to explore viscoelastic breakup physics. In the context of VOF, the method approximates both viscous and elastic characteristics of the saliva with a function based on the Carreau-Yasuda (CY) model. The CY model is traditionally used for modeling blood flow and here is extended to approximate saliva. The foundation of the model couples the shear rate to drive both a variable viscosity and relaxation time. The results indicate a strong stabilizing effect of viscoelastic fluids that indicates that conventional breakup models provide a conservative estimate of droplet size as is relevant to the transmission pathogens.