bluuebunny/crossref_metadata_2025 huggingface dataset:
Fuzzy Method Applied at Energetic and Economic Rehabilitation of Pumping Station
Authors: Radulescu Victorita
Published: October 2021

Many pumping stations require an urgent rehabilitation from hydraulic, energetic, and economic point of view, being older than 30 years. Some urban stations for the water supply are nowadays under-dimensioned compared with the necessary consumption. Such an example is the pumping station of the Buzau City, realized in 1986. Its population has grown in the last decades by about 30% due to industrial development and its water pumping station from the treatment plant is currently totally insufficient. The hydraulic losses through the control discharge valve have become too high. This pumping station ensures the water supply for the south and east part of the city. Firstly, some characteristics of the pumping station equipped with pumps 12NDS- Normal-Double spiral casing-Single-layer of 160kW and 18NDS of 400kW and 500 kW, all from domestic production, are presented. Modernization of the pumping station has started few years ago and being realized in steps, so as not interrupt the city’s water supply. To establish the optimal operating point some algorithms are presented, developed based on the experimental data and using functions with one or two independent variables. Firstly, the interpolation function is determined, followed by its numerical calculation. To establish the characteristics’ equations H = f(Q), P = f(Q), and η = f(Q) starting from experimental results obtained by direct measurements, a polynomial approximation was chosen by the method of the least squares, using the polynomials Lagrange and Bezier. For optimization, the fuzzy technique is adopted regarding the flow fusing, intervals between start and stop following some policies concerning the aggregates’ starting. For a year, the energy saved between these intervals was calculated. Finally, the obtained yields of about 90% proved that the pumps modernization adopting new functioning techniques is more advantageous in some situations than the purchase of new equipment.
Transient Rayleigh-Bénard Thermal Convection With Radiation Heat Transfer in Participating Media Using the Control Volume Finite Element Method (CVFEM) and Lattice Boltzmann Method
Authors: Chaabane Raoudha , Jemni Abdelmajid , Aloui Fethi
Published: October 2021

In this paper, a gas-kinetic Bhatnagar-Gross-Krook (BGK) model is constructed for the Rayleigh-Benard thermal convection transfer in a two-dimensional cavity containing an absorbing, emitting, and scattering medium, where the flow field and temperature field are described by two coupled Lattice Boltzmann Method (LBM) BGK models. Heat radiation is solved using the Control Volume Finite Element Method (CVFEM). The two-dimensional Rayleigh-Benard thermal convection with radiation is studied and numerical results are compared with some available benchmark solutions and a good agreement has been observed.
Performance Analysis of Multi-Sectional Cycloidal Hydrokinetic Turbines
Authors: Li Ang , Wang Yijie , Chen Jun , Jensen Greg , Zhang Haiyan
Published: October 2021

Hydrokinetic power is the most efficient and reliable source of renewable energy and it has been utilized to produce power for centuries. The cycloidal water turbine is a subset of the H-bar type Darrieus turbines that are designed to actively controls the pitch angle of blades to improve turbine efficiency. However, the traditional cycloidal turbine has some shortcomings. For example, the torque and power coefficient vary significantly as the turbine rotates, which means the produced power is not uniform in one revolution. The associated hydrodynamic load will lead to fatigue of the turbine structure that will shorten the turbine lifespan. To solve this problem, a concept of the multi-sectional cycloidal water turbine is proposed. In the present study, computational fluid dynamic (CFD) simulations are applied to investigate the performance of the multi-sectional cycloidal turbine. A cycloidal turbine with three identical sections is designed. Each section consists of three blades and NACA0021 is chosen as the hydrofoil. Structured mesh with sliding interfaces is generated and arbitrary Mesh Interface (AMI) technique is employed. Unsteady RANS simulations with SST k–ω model are conducted to compute the flow field and torque generated by the turbine, and then power coefficient is computed. The results demonstrates that the three-section turbine has uniform performance in one revolution. At the design condition, the power coefficients of the one-section turbine and the three-section turbine are similar; when the TSR is much larger or less than the desired value, the three-section turbine has better performance.
Wake Structures and Effect of Hydrofoil Shapes in Efficient Flapping Propulsion
Authors: Kelly John , Han Pan , Dong Haibo , Van Buren Tyler
Published: October 2021

In this work, direct numerical simulation (DNS) is used to investigate how airfoil shape affects wake structure and performance during a pitching-heaving motion. First, a class-shape transformation (CST) method is used to generate airfoil shapes. CST coefficients are then varied in a parametric study to create geometries that are simulated in a pitching and heaving motion via an immersed boundary method-based numerical solver. The results show that most coefficients have little effect on the propulsive efficiency, but the second coefficient does have a very large effect. Looking at the CST basis functions shows that the effect of this coefficient is concentrated near the 25% mark of the foils chord length. By observing the thrust force and hydrodynamic power through a period of motion it is shown that the effect of the foil shape change is realized near the middle of each flapping motion. Through further inspection of the wake structures, we conclude that this is due to the leading-edge vortex attaching better to the foil shapes with a larger thickness around 25% of the chord length. This is verified by the pressure contours, which show a lower pressure along the leading edge of the better performing foils. The more favorable pressure gradient generated allows for higher efficiency motion.
Effect of Non-Planar Tungsten V-Electrode Pattern in a 3D Printed Microfluidic System
Authors: Parvez Mohammad Salman , Rubby Md Fazlay , Kabir Shanzida , Zulkarnain Meah Imtiaz , Islam Nazmul
Published: October 2021

Manipulation, guiding, and focusing of particles is an important phenomenon in the area of biomedical research. In most cases, particles are suspended in a microfluidic environment. These microfluidic environments can be high or low conductive. Most importantly these flows seeded with the micro-particles are manipulated and guided in microfluidic channels. Microfluidic channels have very low dimensions and considering the flow rate the characteristic of the flow in a microfluidic channel is laminar in nature. There are many micromachining methods available for fabricating microfluidic channels such as soft-lithography, wet etching, electroforming, PDMS molding, laser ablation followed by wet etching but in most of these cases, a microfabrication facility is required which is very costly in nature. Now a days 3D printing process is widely used to design microfluidic channels as a cheap process for conducting laboratory experiments. In this work, a 3D printed microfluidic channel fabrication process was presented along with a CAD drawing with microstructural dimension analysis. Previously V-electrode pattern was used in the static fluid system. In this work, a V-elect rode pattern was inserted in the microfluidic system for the first time to analyze the behavior of the flowing fluid of different conductivity under the application of AC current. The flow characteristics were presented and analyzed with the Reynolds number and the flow region of maximum velocity before and after the implementation of the AC electric field. The direction of the flow was also observed in the V-shaped microfluidics environment.
Effects of Valve Disc on Flow Characteristics Inside a Swing Check Valve During Opening and Closing Processes
Authors: Xu Yi-xiang , Ru Qiang , Yao Huai-yu , Jin Zhi-jiang , Qian Jin-yuan
Published: October 2021

The check valve is one of the most important devices for safety protection of the piping system in thermal and nuclear power plants. As the key component of the check valve, the valve disc accounts for a major effect on the flow characteristics especially during the opening and closing processes. In this paper, a typical swing check valve is taken as the research object. In order to make a comparative study, three working conditions of 30% THA (Turbine Heat Acceptance), 50% THA and 100% THA are selected. Focusing on the effects of valve disc, how does the valve disc motion interact with the flow field around the valve disc is analyzed with the help of the dynamic mesh technology. The results show that under the combined action of fluid force and gravity, the check valve can be opened and closed quickly. During the opening process, the maximum total moment of the disc appears between 45° ∼ 50° opening angle, and during the closing process the maximum total moment occurs when the disc fully closed. The flow field near the valve disc has similar variation rules with the rotation of the valve disc in the three working conditions, and the pressure near the valve disc reaches the maximum value at the moment of opening and closing. This study can provide some suggestions for the further optimal design of similar swing check valve.
Application of OpenFOAM in Numerical Simulations of High-Speed Trains Aerodynamics
Authors: Lu Panpan , Yin Bo , Yang Guowei , Ji Zhanling
Published: October 2021

The present study uses openFOAM package to simulate and investigate the aerodynamic performance and characteristics of high-speed trains (velocity beyond 250 km/h) under typical and critical conditions, which include flow passing a high-speed train, and two trains meeting towards each other at the same velocity in the open air. In terms of different operation conditions, separate openFOAM solvers are adopted. For flow passing a high-speed train at a constant velocity, a steady solver for incompressible, viscous and turbulent flow is employed on a fixed mesh and the results are compared with commercial software Star CCM+. For trains meeting towards each other, overset mesh method is used in which inverse distance interpolation is taken to couple background and inner overset mesh. The built-in mesh generation tool SnappyHexMesh is utilized to generate background and inner overset mesh. In all simulations, k-ω SST two equations RANS model is used to simulate the turbulent flow.
An Investigation on the Bubble Breakup Characteristics by Recirculation Flow in a Venturi Channel
Authors: Ding Guodong , Chen Jiaqing , Li Zhenlin
Published: October 2021

Discrete bubbles can be effectively cracked and dispersed in a Venturi channel with its unique structural characteristics, and the general Venturi channel has been widely used in the practical engineering. Bubble breakup mechanisms based on Venturi channels have been extensively studied, but most of them are based on single bubble or bubble flow pattern. In this paper, the transport process of slug flow in a Venturi channel was explored through visualization experiments, and the characteristics of recirculation flow were indicated by numerical simulation method. The liquid velocity sensitively affects the bubble generation process. With the increase of the liquid velocity, the initial bubble is no longer detached from the gas injector hole, and the gas-liquid flow pattern changes from bubbly flow to slug flow. The slug bubble extends to the diverging section and experiences the process of interface instability, sub-bubble detachment and bubble collapse. The average Sauter bubble diameter decreases with the increase of liquid velocity, and the fitting function is Log Normal. There is a recirculation flow in the side wall region of the diverging section, and the area of the recirculation flow increases with the increase of the liquid velocity at the inlet. The numerical simulation results indicated that there is a large velocity gradient in the boundary region of the recirculation flow under slug flow pattern, which contribute to the bubble collapse.
Impact of Skew Vane Cut on Alternating Stress in a Low Specific Speed Radial Pump Impeller Vane Using Fluid-Structure Interaction (FSI) Simulations
Authors: Gangipamula Rajavamsi , Prajapati Ashish , Birajdar Ravindra , Shukla Shyam
Published: October 2021

Numerical studies are presented on the pressure pulsations, hydraulic excitation forces and alternative stresses produced in a radial volute pump with high head application. The effect of excitation forces due to Rotor-Stator Interaction (RSI) are evaluated using One-way fluid structure Interaction in terms of alternative stresses on impeller pressure side and suction side. Initially, the pump performance parameters are predicted using steady state Computational Fluid Dynamics (CFD) simulations and compared with the available test data. Due to the transient behavior of pressure pulsations, a transient CFD simulation has been conducted using RANS models to predict the pressure pulsations and its behavior with time on impeller vane outlet and tongue locations. These unsteady pressure distributions are further coupled with the Finite element (FE) model of the impeller to solve and monitor for the stresses induced due to the transient hydraulic loading. To attenuate the alternating stresses produced due to RSI, the geometry of the vane is modified by providing a skew cut with 30° at vane outlet. The pressure pulsation amplitude and stresses are reduced by 10% and 10% respectively for a skew cut of 30° at vane trailing edge.
Performance Optimization for Cycloidal Hydrokinetic Turbine With Augmentation Duct for Harvesting Riverine Energy
Authors: Wang Yijie , Li Ang , Jensen Greg , Chen Jun , Zhang Haiyan
Published: October 2021

With the increased demand for developing renewable energy, hydro energy has attracted more attention since it is reliable and easy to acquire. In this area, the cycloidal turbine has been recently studied and applied to ocean energy for its stable and efficient output. Compared to the ordinary vertical/horizontal axis turbine with fixed pitch angle blades (e.g., Darrieus turbine), the cycloidal turbine can maximize the extracted power efficiency by keeping the optimized angle of attack for the blades. Meanwhile, the cycloidal turbine provides a potential solution to solve the problems of self-starting and seasonal flow variations. Introducing an augmentation duct is considered as a method to further increase the incoming flow velocity of the turbine. Inspired by the design of the wind tunnel, a convergent-divergent design of the augmentation duct is developed. One is noted that the dimensions of the augmentation duct are essential to the performance of the duct. In this study, a convergent-divergent augmentation duct is developed based on a 3-blade cycloidal hydro-turbine, operated at a 2 m/s river. Computational fluid dynamic (CFD) analysis with sliding unstructured mesh is applied to investigate the extent how the dimensions of the duct affect the flow velocity to the turbine as well as the extracted power efficiency.
Time Resolved PIV Measurements of a Slot Lobed Jet Issuing Into a Crossflow
Authors: Lewandowski Michael , Kristo Paul , Weiss Abdullah , Kimber Mark
Published: October 2021

The near field mixing phenomenon created by a round jet with three slot lobes exhausting into a crossflow are investigated at a velocity ratio of 0.5. Time-resolved particle image velocimetry measurements provide instantaneous velocity fields of the slotted jet in crossflow, allowing for evaluation of the first and second order turbulent statistics in two perpendicular planes of interest. The independently controlled jet exit and crossflow inlet are first characterized extensively to confirm the velocity ratio and anticipated momentum exchanges. Spanwise and transverse mean velocity profiles reveal that the interaction of the three slot lobes and the center round jet primarily occur in the immediate jet exit region, though residual effects are also found in the wake. Evaluation of the Reynold stresses aims to quantify the near region mixing between the jets collated geometric features and their interaction with the crossflow. Frequency analysis reveals that low-frequency harmonics in the wake region provide greater energy contributions than that of the higher-frequency harmonics found along the leading edge shear layer. This behavior is attributed to the low velocity ratio, where the freestream velocity is twice as large as the jet exit velocity. The experimental data and observations herein serve analogous computational modeling efforts for the slotted jet in crossflow at low velocity ratios, with ample information to inform necessary boundary conditions, fluid properties, and flow fields for validation.
Computational Investigation of Thrust Production of a Dolphin at Various Swimming Speeds
Authors: Wang Junshi , Pavlov Vadim , Lou Zhipeng , Dong Haibo
Published: October 2021

Dolphins are known for their outstanding swimming performance. However, the difference in flow physics at different speeds remains elusive. In this work, the underlying mechanisms of dolphin swimming at three speeds, 2 m/s, 5 m/s, and 8 m/s, are explored using a combined experimental and numerical approach. Using the scanned CAD model of the Atlantic white-sided dolphin (Lagenorhynchus acutus) and virtual skeleton-based surface reconstruction method, a three-dimensional high-fidelity computational model is obtained with time-varying kinematics. A sharp-interface immersed-boundary-method (IBM) based direct numerical simulation (DNS) solver is employed to calculate the corresponding thrust production, wake structure, and surface pressure at different swimming speeds. It is found that the fluke keeps its effective angle of attack at high values for about 60% of each stroke. The total pressure force coefficient along the x-axis converges as the speed increase. The flow and surface pressure analysis both show considerable differences between lower (2 m/s) and higher (5 m/s and 8 m/s) speeds. The results from this work help to bring new insight into understanding the force generation mechanisms of the highly efficient dolphin swimming and offer potential suggestions to the future designs of unmanned underwater vehicles.
Numerical Simulation of a Canadian Well With Several Circumferential Rows of Internal Vortex Generators
Authors: Kharoua Nabil , Semmari Hamza , Korichi Houssem , Haroun Mehdi
Published: October 2021

Canadian Wells exploit the quasi-stable underground temperature throughout the year for cooling and heating applications. This type of heat exchangers is used in residential buildings, agriculture and industry. Implementing Vortex Generators (VGs) is intended to disturb the thermal and dynamic boundary layers developing in the near-wall regions leading to the increase of the heat transfer coefficient.

The present work investigates the positive effects of a sequence of several rows of VGs. The commercial code ANSYS FLUENT was used to perform numerical simulations mimicking the variation of the seasonal operational conditions occurring within one year. The ambient conditions were considered for the city of Constantine located in the east of Algeria at an altitude of 600m over the sea level. Sinusoidal functions of time and depth, were used for the yearly variations of the ground and air temperatures. Parallelepiped VGs were considered in this study. The Reynolds number was in the range Re = 14975–42789.

The results illustrated a contrasting effect of the Reynolds number on the heat transfer coefficient and the temperature difference between the inlet and outlet of the Canadian Well. In terms of number of VGs rows, the beneficial heat transfer effects were observed till the fifth row only.
Flow Characterization in the Upper Cavity of a Rotary Compressor
Authors: Wu Puyuan , Li Ang , Chen Jun , Sojka Paul E. , Li Yang , Cao Hongjun
Published: October 2021

As hundreds of millions of Air conditioning (AC) systems are produced each year, and many of them use rotary compressors as the heat pump, optimizing the flow inside the rotary compressor to improve its reliability and efficiency becomes a key issue of the manufactures. Since the invention of the rotary compressor, its internal flow has been studied numerically with real models. However, a rotary compressor’s internal flow can be extremely complicated due to the complex internal structures’ geometry and high-speed moving parts, making it difficult to interpret the result by CFD simulation and repeat the simulation in different models. In our experiments for observing lubricant oil droplets above the rotor/stator in a rotary compressor, droplets’ movement reveals that two major effects control the gas flow in the compressor’s upper cavity. One is the swirling jet produced by the high-speed rotating rotor with no-slip condition on its sidewall. The other one is the rotating disk effect induced by the top of the high-speed rotating rotor. Either of them has been studied individually in different areas. For example, the swirling jet is often used in combustors while the rotating disk is applied in the viscous pump. However, the coupling of these two effects in the rotary compressor with different velocity ranges, size scales, and fluid properties has not been studied according to our best knowledge. In our simulation, a model that only consists of a simplified rotor, simplified stator, sidewall, and discharge tube (outlet) is built. Thus, the effect by small parts, such as the balance block and coils, is excluded. The rotor is set to rotate at 30, 60, and 90 Hz. Uniform velocity calculated with the theoretical flow rate and ambient pressure conditions are given at the inlet (rotor/stator clearance) and outlet, respectively. No-slip conditions are defined at other walls. Steady-state K-ω SST turbulence models are applied, and the cases are computed with OpenFoam. The CFD results show an inner recirculation zone above the rotor that creates a downward velocity component above the rotor and an outer circulation zone above the stator. The CFD result meets the observation of the droplets’ movement above the rotor/stator. With the CFD results and the experiment’s observations, we propose the model of the oil droplet’s path in the rotary compressor’s upper cavity, which can help reduce the exhausted lubricant oil droplets from the compressor.
CFD Simulation of COVID Aerosol Dispersion in Indoor Environments
Authors: Abushamleh Mohammed , Zhang Ning
Published: October 2021

Computational Fluid Dynamics simulations for the droplet’s dispersion generated by a cough in an indoor background, droplets trajectory, and evaporation time are predicted to be related to the droplet’s diameter and relative humidity. In general, medium-size droplets have higher axial penetration potential, and large droplets tend to settle on the ground due to gravity. Also, larger droplets take a longer time to evaporate. Smaller droplets tend to be suspended in the flow field with small penetration potential and tend to fade faster; smaller droplets < 20 μm evaporate completely before the simulation time reaches 0.75 sec. To study the effect of Relative Humidity (RH) on the evaporation rate, in particular, the present study offers three simulations, all with the same standard room conditions, only differ in relative humidity s 40%, 60%, and 90%. Another source of variability is the cough-expired volume. This study adopts existent experimental work to establish two cough flow rate profiles. The Lagrangian discrete phase model is adopted along with the species model to track and investigate the cough droplet dispersion and evaporation.
Large Particle Separation From Non-Newtonian Slurries Using Bump Arrays
Authors: Pease Leonard F. , Bamberger Judith Ann , Burns Carolyn A. , Minette Michael J.
Published: October 2021

Here we evaluate the performance of bump arrays to separate large particles from non-Newtonian slurries with Bingham and Cross rheology. Bump arrays in deterministic lateral displacement devices separate large particles from small particles using arrays of staggered posts. Large particles, defined as those with radii larger than the distance between the edge of a post and the stagnation streamline from the next downstream post, must bump toward one side of the device, whereas particles smaller than this distance slalom from entrance to exit without net lateral displacement. Although these devices have been used to separate a wide variety of large particles from blood cells to sand, partition of large particles from non-Newtonian fluids remains unexplored. Yet, an important set of modestly concentrated slurries, including Hanford nuclear waste, displays non-Newtonian rheology. Here we evaluate the influence of non-Newtonian rheology on the large-small particle size cutoff in bump arrays using a model that explores the influence of yield stresses, ratios of zero and infinite shear viscosities, and Cross’s exponent under strictly laminar well-developed conditions. Surprisingly, we find that viscosity ratios and Cross’s exponent make no significant difference on the particle cutoffs between large particles that bump and small particles that slalom around the posts from entrance to exit. In contrast, we find that yield stresses do significantly affect the size cutoff. As the yield stress increases, velocity profiles become more plug like lowering the size cutoff. For nuclear waste separations where removing large particles is a priority, increasing yield stresses is conservative.
An Experimental Study on the Effects of Burst Pressure on Air Blast Development in a Blast Wave Simulator
Authors: Zieg Parker , Benson John , Liu Yang
Published: October 2021

Due to the extensive use of explosive devices in military conflicts, there has been a dramatic increase in life-threatening injuries and resultant death toll caused by explosive blasts. In an attempt to better understand the blast waves and mitigate the damages caused by such blast waves, various devices/systems have been developed to replicate the field blast scenarios in laboratory conditions. The East Carolina University Advanced Blast Wave Simulator (i.e., ECU-ABWS) is one such facility that can reproduce blast waves of various shapes and profiles. The peak overpressure of a blast is the key factor that causes the greatest number of damages, and it is essentially determined by the burst pressure of the blast. Therefore, a better understanding of the effects of burst pressure on blast generation and development is strongly desired to develop safer and more effective blast mitigation technologies. In the present study, a series of experiments were carried out in the ECU-ABWS to characterize the blast waves generated under different burst pressure conditions. While the incident (side-on) pressures at multiple locations along the blast propagation direction were measured using a temporally-resolved multi-point pressure sensing system, the time-evolutions of blast wave profiles were also qualitatively revealed by using a high-speed Schlieren imaging system. The synchronization of pressure sensing and Schlieren image acquisition enables us to extract more physical details of the dynamic blast wave development under different burst pressure conditions by associating the incident pressures and shock wave morphologies. In this study, the different burst pressures were achieved by altering the thickness of the membrane separating the driver section of pressurized gas and the driven section of air at atmospheric pressure. It is found that there is a linear relationship between the burst pressure and the peak overpressure. As the burst pressure increases (by increasing the membrane thickness), more clearly defined shock wavefronts are also observed along with the peak overpressure increase.
Viability of OpenFOAM as the Numerical Engine for Augmented Reality Sandbox
Authors: Smith Elizabeth
Published: October 2021

Many augmented reality sandboxes use a single purpose implementation of standard numerical schemes to solve the Saint-Venant equations for shallow water in real time. This work evaluates the open-source computational fluid dynamics (CFD) package OpenFOAM as an alternative to the custom implementations traditionally used. Many sandboxes are used in educational and research settings and CFD engines with costly licensing was not desirable. The goal of this work is to identify or create an OpenFOAM solver that handles features such as dry conditions and complex topographies. The existing shallowWaterFoam solver was identified as the best candidate but required modification to handle scenarios representative of the target application. Replacing the existing custom numerical algorithm with the OpenFOAM software will more easily allow future incorporation additional phenomena.
Numerical Study on a Flow Field in the Rinsing Process of a Beverage Can Transported With a Constant Velocity
Authors: Kawachi Tatsuma , Sasaki Takuto , Kaneko Aya , Nishio Yu , Ogawa Takanobu
Published: October 2021

The present study investigates the flow field in a rinsing process of a beverage can numerically and experimentally. The three-dimensional Navier-Stokes equations are solved with a finite volume method along with the volume of fluid (VOF) method for free surface. The beverage can set upside down is transported with a constant velocity and rinsed with a water jet ejected from a nozzle below the can. The case of a can at rest is also simulated. The result shows that the ejected water impinges on the can bottom and spreads along the side surface of the can. Then, as it flows down toward the can mouth, its front surface forms splashes. For the stationary can case, after the jet impinges on the can bottom, it almost evenly spreads over the side surface. The water flows downward and becomes branched flows by fingering. The time average of VOF is calculated to visualize the regions rinsed by water. For the case of a moving can, only the top region of the can is rinsed, and the ratio of the rinsed region drops to 29% from 69% for the stationary case. The computed water surfaces qualitatively agree with the experimental result, but the shape of the front surface, such as splashes and fingerings, cannot be resolved with the simulation.
A Single-Camera Synthetic Schlieren Method for Measuring Two-Dimensional Liquid Surfaces
Authors: Xu Duo , Li Huixin , Avila Marc
Published: October 2021

A single-camera synthetic Schlieren method is introduced here to measure two-dimensional topography and depth of dynamic free liquid surfaces. The method is simple and easy to implement. Because of light refraction (following Snell’s law), markers on a flat bottom which are seen through the surfaces of a transparent liquid are virtually displaced. This leads to a governing equation that the liquid surface depth (and its topography) is associated with the marker displacement. In the equation, the refractive index of the liquid (e.g. water) can be obtained by a refractometer (or from a technical reference), and the displacements of the markers can be obtained by a cross-correlation method which is usually used in particle image velocimetry. In the equation, the only unknown, the depth of the surface, can be obtained by solving the governing equation with boundary conditions. Unlike free-surface synthetic Schlieren (FS-SS) of Moisy et al. (Exp. Fluids, 1021, 46, 2009), our method does not require a reference depth (which is obtained before or after experiments), so that flows with temporally evolving depth can be measured. Experiments of liquid ripples and dam-break flows were performed to test the method. The results agree well with those obtained with FS-SS and visualization measurements.
Can Bump Arrays Separate Particles From Turbulent Flows?
Authors: Pease Leonard F. , Serkowski Jason , Veldman Timothy G. , Willams Jonathan , Yu Xiao-Ying , Minette Michael J. , Bamberger Judith Ann , Burns Carolyn A.
Published: October 2021

In this paper, we evaluate the hypothesis that bump arrays can be used to separate particles from turbulent flows entering the array. Microfluidic bump arrays are known for separating particles by size from laminar inlet flows. However, turbulent inlet flows have not been explored but become important as microfluidic bump arrays are scaled up to mesofluidic bump arrays. We find experimentally that particle separation is indeed effective at higher Reynolds numbers. These experimental findings portend industrial scale particle separation due to the higher flow rates they facilitate.
Behavior of Pseudomonas aeruginosa strains on the nanopillar topography of dragonfly (Pantala flavescens) wing under flow conditions
Authors: Kamarajan Banu Pradheepa , Ananthasubramanian Muthusamy , Sriramajayam Lavanya , Boppe Appalaraju
Published: October 2021

Bacterial associated infection is a threat in the medical field. Pseudomonas aeruginosa, one of the major causative agents for nosocomial infection, has developed resistance to almost all the classes of antibiotics. Recently, nanopillar-like structures were identified on the wings of insects such as cicada and dragonfly. Nanopillars both on natural surfaces and those mimicked on artificial surfaces were reported to possess bactericidal activity against a wide range of bacteria. An earlier study reported strain specific variation in the viability of P. aeruginosa on the nanopillar topography of a dragonfly wing under static condition. Here, we report the behavior of P. aeruginosa strains on a dragonfly wing under hydrodynamic conditions. The results of the study indicated that, under hydrodynamic conditions, P. aeruginosa PAO1 was attached in higher numbers to the wing surface than P. aeruginosa ATCC 9027 but killed in lower numbers. The plausible reason was identified to be the masking of nanopillars by the secreted extracellular polysaccharide. The shear rate of 1.0 s−1 showed a relatively higher bactericidal effect among the three tested shear rates.
Owner–Resident Ideological Divergence and Firm Performance: Evidence From Major League Baseball
Authors: Hayduk Ted
Published: October 2021

Stakeholder frameworks document the nature of sport franchise owners’ interactions with local residents, but there has been little attention on understanding why interactions develop a contentious or collaborative tenor. There has also been little emphasis on understanding whether and how interactions affect revenue-side outcomes. This paper uses the team identification literature to buttress the idea that owners are meaningful points of attachment for fans. It also uses consumer political ideology scholarship to explain that owners’ ideologies—never more visible than today—are important predictors of consumption. The paper proposes and tests a series of hypotheses about the effect of owners’ and residents’ ideological divergence on attendance and spending. Similar ideologies between residents and long-tenured owners were associated with about $8–$10 more spending per fan per game, as well as 2,400–3,950 more fans per game. Implications for academics and practitioners are provided.
YAP drives fate conversion and chemoresistance of small cell lung cancer
Authors: Wu Qingzhe , Guo Jingxin , Liu Yuning , Zheng Qi , Li Xiaoling , Wu Chuanqiang , Fang Dong , Chen Xin , Ma Liang , Xu Pinglong , Xu Xiaofang , Liao Cheng , Wu Ming , Shen Li , Song Hai
Published: October 2021

YAP confers small cell lung cancer with the intratumoral heterogeneity and resistance to chemotherapy drugs.
Single alloy nanoparticle x-ray imaging during a catalytic reaction
Authors: Kim Young Yong , Keller Thomas F. , Goncalves Tiago J. , Abuin Manuel , Runge Henning , Gelisio Luca , Carnis Jerome , Vonk Vedran , Plessow Philipp N. , Vartaniants Ivan A. , Stierle Andreas
Published: October 2021

We have imaged a single alloy catalyst nanoparticle at work, resolving its facet surface composition.
Evolutionary adaptation of visual pigments in geckos for their photic environment
Authors: Kojima Keiichi , Matsutani Yuki , Yanagawa Masataka , Imamoto Yasushi , Yamano Yumiko , Wada Akimori , Shichida Yoshinori , Yamashita Takahiro
Published: October 2021

Nocturnal and diurnal gecko cone pigments changed their spontaneous activation rates to adjust to their activity rhythm.
Magnetostratigraphy and magnetic properties of the Jurassic to Lower Cretaceous Girón Group (northern Andes, Colombia)
Authors: Jiménez Giovanny , García-Delgado Helbert , Geissman John W.
Published: October 2021

We report paleomagnetic results from the Jurassic to Lower Cretaceous continental sedimentary succession exposed in the eastern limb of the Los Yariguíes anticlinorium, Eastern Cordillera, Colombia. About 820 m of a stratigraphic section of the upper part of the Girón Group (Angostura del Río Lebrija and Los Santos Formations) was sampled to construct a magnetic polarity stratigraphy. A total of 199 independent samples that yield interpretable and acceptable data have a characteristic remanent magnetization component (ChRM) isolated between 400 °C and 680 °C in progressive thermal demagnetization. Demagnetization behavior and rock magnetic properties are interpreted to indicate that hematite is the principal magnetization carrier with a possible contribution by magnetite in some parts of the section. After tilt correction, 123 samples are of normal polarity (declination [D] = 44.9°, inclination [I] = +9.7°, R = 110.64, k = 9.87, and α95 = 4.3°), and the other 76 accepted samples are of reverse polarity (D = 216.4°, I = −6.1°, R = 68.29, k = 9.72, and α95 = 5.5°). The statistical reversal test conducted on virtual geomagnetic poles is positive (class B). Based on paleontologic age estimates for the Cumbre and Rosablanca Formations, we assume a Berriasian age for the Los Santos Formation. The magnetostratigraphic data from the Girón Group strata are interpreted to suggest an age for the sampled part of the section between early Kimmeridgian and early Valanginian (ca. 157–139 Ma). The age of the Angostura del Río Lebrija Formation is estimated as between early Kimmeridgian and early Tithonian (ca. 157–146.5 Ma). The age of the Los Santos Formation is estimated between early Tithonian and early Valanginian (146.5–139.3 Ma). With our proposed, but nonunique, correlation with the Geomagnetic Polarity Time Scale, the Jurassic-Cretaceous boundary is interpreted to be located within the Los Santos Formation. The Girón Group is characterized by two periods of high (>8 cm/k.y.) and two periods of low (< 2 cm/k.y.) sedimentation rates. An inferred clockwise rotation of ∼44°, based on paleomagnetic declination data from the Girón Group, is similar to rotation estimates reported in some previous studies in the general area, and this facet of deformation could be related to local and regional response to displacement along regional-scale strike-slip faults.
Novel application of infliximab for diversion colitis
Authors: Kido Miori , Tamura Ryo , Yasui Yoshitomo , Okajima Hideaki
Published: October 2021

Diversion colitis (DC) that was refractory to standard treatments was successfully treated with infliximab. A 24-year-old man with a transverse colostomy suffered from severe DC. Topical steroids, 5-aminosalicylic acid (5-ASA) enemas and synbiotics were initially effective, and the colostomy was successfully closed with a covering ileostomy to minimise the risk of anastomotic leakage owing to the damaged colon. DC subsequently relapsed in the entire colon and was refractory to the previous protocol and autologous faecal transplantation. Intravenous methylprednisolone and oral 5-ASA were discontinued owing to possible adverse effects. Infliximab with intravenous prednisolone was introduced, and the protocol was so effective in suppressing the acute colitis that total colectomy was avoided. The stoma was subsequently closed, and the patient is currently symptom-free. Infliximab is used for ulcerative colitis but could also be effective against severe DC.
MRI findings seen in serous atrophy of bone marrow
Authors: Kalamar Vilim , Davies Alun , Wright Peter , Suresh Priya
Published: October 2021

An 85-year-old man was referred for an MRI scan of the pelvis for further evaluation of a suspected left neck of femur fracture, which was regarded as equivocal on plain radiograph and CT. The initial MRI demonstrated unusual appearances of the visualised bone marrow and subcutaneous adipose tissue and was initially misinterpreted as a technical malfunction of the scanner. However, a repeat study on a different scanner the following day once again demonstrated the same appearances. The appearances were consistent with serous atrophy of bone marrow, a non-neoplastic disorder of the bone marrow, which is most commonly seen in severe anorexia nervosa or cachexia. These unusual, but distinct, bone marrow and subcutaneous adipose tissue appearances, which are specific to MRI, have been colloquially termed as the ‘flip-flop’ effect.
Disruption in essential health services in Mexico during COVID-19: an interrupted time series analysis of health information system data
Authors: Doubova Svetlana V , Leslie Hannah H , Kruk Margaret E , Pérez-Cuevas Ricardo , Arsenault Catherine
Published: October 2021

Introduction

The COVID-19 pandemic has disrupted health systems around the world. The objectives of this study are to estimate the overall effect of the pandemic on essential health service use and outcomes in Mexico, describe observed and predicted trends in services over 24 months, and to estimate the number of visits lost through December 2020.

Methods

We used health information system data for January 2019 to December 2020 from the Mexican Institute of Social Security (IMSS), which provides health services for more than half of Mexico’s population—65 million people. Our analysis includes nine indicators of service use and three outcome indicators for reproductive, maternal and child health and non-communicable disease services. We used an interrupted time series design and linear generalised estimating equation models to estimate the change in service use and outcomes from April to December 2020. Estimates were expressed using average marginal effects on the risk ratio scale.

Results

The study found that across nine health services, an estimated 8.74 million patient visits were lost in Mexico. This included a decline of over two thirds for breast and cervical cancer screenings (79% and 68%, respectively), over half for sick child visits and female contraceptive services, approximately one-third for childhood vaccinations, diabetes, hypertension and antenatal care consultations, and a decline of 10% for deliveries performed at IMSS. In terms of patient outcomes, the proportion of patients with diabetes and hypertension with controlled conditions declined by 22% and 17%, respectively. Caesarean section rate did not change.

Conclusion

Significant disruptions in health services show that the pandemic has strained the resilience of the Mexican health system and calls for urgent efforts to resume essential services and plan for catching up on missed preventive care even as the COVID-19 crisis continues in Mexico.
Cardiological Disease in the Armed Forces: A Clear and Present Danger
Authors: Fisher Nicholas G. , Nicol Edward D.
Published: October 2021

Despite a younger cohort of individuals than typically found in other large organisations the Armed Forces are not free from cardiac disease. Indeed some conditions are more frequently found and the high risk occupations of individuals within the Armed Forces makes it imperative that all cardiac conditions are identified rapidly and correctly. By illustrating actual cases, we highlight the need for service personnel to have rapid access to expert cardiological expertise, from individuals with an in depth occupational knowledge of the Armed Forces, 365 days per year.
Patients’ Perception of Military Doctors in Fracture Clinics - does the Wearing of Uniform Make a Difference?
Authors: McLean Christopher , Patel Pareeta , Sullivan Carl , Thomas Mark
Published: October 2021

We performed a study during our Trauma Week when patients who were referred from the accident department with fractures were reviewed in our fracture clinic. During our Trauma Week, Mister Thomas, Consultant Orthopaedic and Trauma Surgeon or Surgeon Lieutenant Commander McLean, Specialist Registrar in Orthopaedic and Trauma Surgery reviewed a total of 93 patients in fracture clinic. All patients were given an anonymous questionnaire regarding their perceptions of their attending clinician, 77 were completed. Forty-nine questionnaires regarding Surgeon Lieutenant Commander McLean and 28 regarding Mister Thomas were available for analysis. During the Trauma Week all patients were seen in the same location in identical cubicles by either of the two clinicians, consultations were typically brief lasting about five minutes. Throughout the week the clinicians, one military and one civilian, wore differing attire. The military uniform comprised Royal Navy number four action working dress. The civilian attire comprised ‘dog-robbers’ (jacket, shirt with tie and smart trousers). The hypothesis tested was that the use of military uniform might alter patients’ perceptions of their attending clinician. Our results appear to demonstrate that the attire of the attending clinician does not adversely influence patients’ perceptions of their attending clinician.
Patterns of stability and change in the maize genome: a case study of small RNA transcriptomes in two recombinant inbred lines and their progenitors
Authors: Minow Mark A.A. , Lukens Lewis , Rossi Vincenzo , Colasanti Joseph
Published: October 2021

Small RNAs (sRNAs) are epigenetic regulators of eukaryotic genes and transposable elements (TEs). Diverse sRNA expression patterns exist within a species, but how this diversity arises is not well understood. To provide a window into the dynamics of maize sRNA patterning, sRNA and mRNA transcriptomes were examined in two related Zea mays recombinant inbred lines (RILs) and their inbred parents. Analysis of these RILs revealed that most clusters of sRNA expression retained the parental sRNA expression level. However, expression states that differ from the parental allele were also observed, predominantly reflecting decreases in sRNA expression. When RIL sRNA expression differed from the parental allele, the new state was frequently similar between the two RILs, and similar to the expression state found at the allele in the other parent. Novel sRNA expression patterns, distinct from those of either parent, were rare. Additionally, examination of sRNA expression over TEs revealed one TE family, Gyma, which showed consistent enrichment for RIL sRNA expression differences compared to those found in parental alleles. These findings provide insights into how sRNA silencing might evolve over generations and suggest that further investigation into the molecular nature of sRNA trans regulators is warranted.