bluuebunny/crossref_metadata_2025 huggingface dataset:
Identify Attractive and Unattractive Individuals Based on Geometric Features Using Neural Network
Authors: Ahmadimehr Shakiba , Moridani Mohammad Karimi
Published: September 2021

This paper aims to explore the essence of facial attractiveness from the viewpoint of geometric features toward the classification and identification of attractive and unattractive individuals. We present a simple but useful feature extraction for facial beauty classification. Evaluation of facial attractiveness was performed with different combinations of geometric facial features using the deep learning method. In this method, we focus on the geometry of a face and use actual faces for our analysis. The proposed method has been tested on, image database containing 60 images of men's faces (attractive or unattractive) ranging from 20-50 years old. The images are taken from both frontal and lateral position. In the next step, principle components analysis (PCA) was applied to feature a reduction of beauty, and finally, the neural network was used for judging whether the obtained analysis of various faces is attractive or not. The results show that one of the indexes in identifying facial attractiveness base of science, is the values of the geometric features in the face, changing facial parameters can change the face from unattractive to attractive and vice versa. The experimental results are based on 60 facial images, high accuracy of 88%, and Sensitivity of 92% is obtained for 2-level classification (attractive or not).
A jelenkori nyelvjárási adatok történeti dialektológiai forrásértéke
Authors: Bába Barbara
Published: September 2021

A nyelvjárástörténet szinte axiómaként kezeli azt a megállapítást, amely szerint a mai nyelvjárásokban - a nyelvjárások eltérő ütemű és irányú történeti változása révén - egymás mellett adatolhatók bizonyos nyelvi jelenségek különböző változási fázisai. Ebből pedig az is kétségtelenül következik, hogy a mai nyelvjárások fontos forrását jelenthetik a történeti nyelvjáráskutatásnak. A korabeli adatok értékelése, bizonyítási értékük vizsgálata azonban bizonyos módszertani akadályokkal jár. Így például a hangtani szembenállások változása, vagy a településtörténeti, népvándorlási folyamatok következtében a korabeli nyelvjárásokban fellelhető nyelvi jelenségek bizonyos korai nyelvjárási sajátosságok lokalizálására csak korlátozottan használhatók. A mai nyelvjárási adatok azonban sok tekintetben valódi útmutatást nyújthatnak a történeti dialektológia bizonyos megfigyeléseihez. Ennek illusztrálására dolgozatom különböző hangtani jelenségeket mutat be, amelyek vizsgálatában a mai nyelvjárási adatok hiteles forrást jelenthetnek a történeti dialektológiához. Ezt egy konkrét probléma vizsgálata követi, nevezetesen annak a kérdésnek a vizsgálata, nevezetesen az a kérdés, hogy miért lehet problémás az ö-zéssel kapcsolatos jelenkori nyelvjárási adatokra támaszkodni (nem pedig más dialektusok ë-jére) az ü-zés gócpontjainak kialakítása során. Ugyanezek az összefüggések az ómagyar korban is problematikusak lehetnek.
A szegmentumok bemutatása a régi magyar grammatikában (1. rész)
Authors: C. Vladár Zsuzsa , Markó Alexandra
Published: September 2021

A korai magyar nyelvtanok és a latin nyelven írt magyar nyelvtani irodalom számos leírást tartalmaz a magyar szegmensleltárral egészében, vagy egyes fonémák összefüggésében. A cikk egyik célja, hogy bemutassa a nyelvtani szerzők által a magyar szegmensleltár jellemzésére használt terminológiát. A tanulmány megvizsgálja az egyes szerzők műveiben szereplő terminológia eredetét és változatait, valamint a szegmensek halmazával, tagolásával és az általuk kiváltott pszichoakusztikus képpel kapcsolatos kortárs feltételezéseket is. A dolgozat másik célja annak vizsgálata, hogy a modern kísérleti fonetika eredményei miként kapcsolódhatnak a korai grammatikusok által alkalmazott metaforikus leírásokhoz, és milyen jellegű, kísérleti adatokkal alátámasztott artikulációs-auditív tapasztalatok vezethettek a szegmensek jellemzésére használt terminológia fejlesztéséhez.
Az eljátszogat, elénekelget-féle alakok aspektuális megítéléséről
Authors: Szili Katalin
Published: September 2021

Ez a cikk az el- „eltávol” delimitatív verbális előtag aspektuális jellemzőinek ellentmondásos voltát, valamint az esemény alapigével kifejezett időbeli korlátait, annak atelikus jellegét tárgyalja. Mivel az atelikus – telikus oppozícióhoz kapcsolódó jellemzők részletes elemzése megerősítette, hogy a két jellemző alkalmatlan a megfelelő leírásra, a szerző a szláv aspektustanulmányok terminativitásának fogalmát használta az igék egy halmazának aspektuális azonosítására. A szerző hasonló megközelítésekkel összhangban a terminativitást, amely az események általános, külső és belső időbeli lehatárolását jelenti, három csoportra osztotta: abszolút telikára, relatív telikára és egyszerű terminatívára. Ez utóbbi kategória olyan eseményeket foglal magában, amelyek csak időben korlátozottak. A három terminatívus csoport hatékony eszközt nyújt nemcsak a delimitatívok, hanem a skaláris változás igék kategorizálására is, ez a legnagyobb szemantikai csoport, amely felfedi a telikitás relatív természetét: az előtag nélküli változataik a relatív alcsoportba tartoznak, míg az előtaggal rendelkezők az abszolút telic alcsoport. Ezt a kategorizálást befolyásolhatják a pragmatikus körülmények.
İş Yeri Nezaketsizliğinin Örgütsel Vatandaşlık Davranışına Etkisinde Psikolojik Sözleşme İhlalinin Aracılık Rolü
Authors: Doğan Selen , Karaçelebi Fatma Gül
Published: September 2021

Örgütlerde nezaketsiz davranışların meydana gelmesi olumsuz sonuçları beraberinde getirmektedir. Bu araştırmada iş yeri nezaketsizliğinin örgütsel vatandaşlık davranışına etkisinde psikolojik sözleşme ihlalinin aracılık rolü araştırılmıştır. 246 kamu personelinden veri toplanmıştır. Yapılan regresyon analizi sonucunda, iş yeri nezaketsizliğinin örgütsel vatandaşlık davranışı üzerinde ters yönde anlamlı bir etkisinin olduğu, yapılan aracılık analizi sonucunda bu etkinin bir kısmının psikolojik sözleşme ihlali aracılığıyla gerçekleştiği görülmüştür. Bu sonuç, iş yeri nezaketsizliğinin örgütsel vatandaşlık davranışı üzerindeki etkisinde psikolojik sözleşme ihlalinin etki ettiğini anlatmaktadır. Bu bulgulara göre iş yeri nezaketsizliğinin örgütsel vatandaşlık davranışının azalmasında etkili olduğu ancak psikolojik sözleşme ihlalinin aracılık etkisi ile birlikte özellikle çalışanların kurum ile olan ilişkisinin olumsuz etkilendiği görülmüştür.
PIV investigation of cavitating flows around circular cylinders with hydrophobic coatings
Authors: Dobroselsky Konstantin , Lebedev Anatoliy , Safonov Alexey , Starinskiy Sergey , Dulin Vladimir
Published: September 2021

The treatment of the hydrophobic properties of solid surfaces is considered as a passive method to reduce the drag in water flows (Rothstein, 2010) and to potentially affect the flow separation and vortex shedding (Sooraj et al., 2020). The manufacturing of surfaces with micro- and nano-scale roughness allows to extend the hydrophobicity towards superhydrophobicity with the contact angle close to 180°. In such conditions the solid surface is not wetted completely and the air-water interphase partially remains on the surface texture. This results in so-called flow slip effect. Therefore, a local phase transition during the flow cavitation or gas effervescence in near-wall low-pressure regions may additionally affect the slip effect for hydrophobic surfaces. The present work is focused on the comparison between cavitating and noncavitating flows around circular cylinders with lateral sectors with hydrophobic and non-hydrophobic coatings. The experiments are performed in a water tunnel, which consists of a water outgassing and cooling/heating section, honeycomb, contraction section, test section and diffuser. The water flow is driven by an electric pump, providing a bulk velocity up to 10 m/s in the transparent test section with 1 m length and 80×150 mm2 rectangular cross-section. The facility is equipped with an ultrasonic flowmeter, temperature and pressure sensors. Besides, the static pressure inside the water tunnel can be varied by using a special shaft section. The measurements are performed by using high-repetition and low-repetition PIV systems. The former is used for the analysis of large-scale flow dynamics in the wake region, whereas the latter one is used for high-resolution measurements in near-wall regions by using a long-distance microscope. The Reynolds number based on the bulk velocity of the flow, diameter of the cylinders (D = 26 mm) and kinematic viscosity of the water is varied up to 2×105..
Hilbert transform revisited – Proper orthogonal decomposition applied to analytical signals of flow fields
Authors: Kriegseis Jochen , Kinzel Matthias , Nobach Holger
Published: September 2021

The modes delivered by proper orthogonal decomposition (POD) are uncorrelated as per definition; but interestingly, they are not necessarily independent in terms of spatio-temporal flow-pattern dynamics. For instance, periodic structures that travel as waves through a series of snapshots often consist of pairs of modes with harmonic functions shifted 90 degree in phase and/or a spatial offset by a quarter of the spatial wave length of the convective flow pattern. Identification of such pairs, however, largely builds upon experience, visual inspection and/or the analysis of the reconstructed coefficients in cyclograms (Lissajous figures). This effort becomes even more challenging if measurement noise or other spurious information contaminates the raw data under consideration. One possibility to automatically pair corresponding patterns with common POD algorithms is the immediate application of the POD method to complex data (see Pfeffer et al., 1990). As outlined by Horel (1984), the Hilbert transform is a well-known and straight forward means to obtain the required extension of the original signal with an appropriate 90 degrees phase shift, which is independent of the fundamental frequencies. The complex extension of the original (real) signal Xi and its (discrete) Hilbert transform HT{Xi} as the imaginary part Xi +iHT{Xi} with the imaginary unit i is commonly known as the so-called analytical signal.
Time-resolved flow field investigation in an industrial centrifugal compressor application involving TR-PIV synchronized with unsteady pressure measurements
Authors: Klinner Joachim , Voges Melanie , Schroll Michael , Bassetti Alessandro , Willert Christian
Published: September 2021

We report on combined velocity and unsteady pressure measurements obtained on an radial compressor with vaneless diffuser and asymmetric volute. Time-resolved PIV recordings were acquired at 26 kHz both upstream of the impeller as well as within the vaneless diffusor at several rotation speeds at clean conditions and prior to the onset of instabilities within the rotor. The velocity data was acquired with a high-repetition rate, double-pulse laser system consisting of two combined DPSS lasers and a high-speed CMOS camera that was synchronized with multi-point unsteady pressure measurements. Details on the facility, the utilized instrumentation and data processing are provided with particular focus on the spectral and coherence analysis. Power spectra obtained from time records of the inlet velocity and unsteady pressure reveal an increase of low-frequency fluctuations below the blade passing frequency and the occurrence of a mode-locked behaviour indicating the presence of rotating instabilities. High levels of correlation between velocity and unsteady pressure signals not only confirm the temporal coherence of the acquired data but also reveal a direct coupling between flow field and pressure signature that is more prominent upstream of the rotor rather than in the diffusor.
Experimental Study of Darrieus Turbines in Confined Free-Surface Flows
Authors: Kara Mostefa Larbi , Chatellier Ludovic , Thomas Lionel
Published: September 2021

Both scientific and industrial communities have a growing interest for marine renewable energies. There is a wide variety of technologies in this domain, with different degrees of maturity. Our work focuses on two models of an H-type vertical axis Darrieus (1931) tidal turbine with the objective of studying the effect of fluid-structure interactions on their performances. Theexperimental studies were carried out on the 15m long and 1m2 square section free surface channel of the Environmental Hydrodynamics Platform at PPRIME Institute (Figure 1). The maximum flow discharge through the channel is Q = 500 l/s.
A network-based perspective on coherent structure detection from very-sparse Lagrangian data
Authors: Iacobello Giovanni , Rival David E.
Published: September 2021

Coherent structure detection (CSD) is a long-lasting issue in fluid mechanics research as the presence of spatio-temporal coherent motion enables simpler ways to characterize the flow dynamics. Such reducedorder representation, in fact, has significant implications for the understanding of the dynamics of flows, as well as their modeling and control (Hussain, 1986). While the Eulerian framework has been extensively adopted for CSD, Lagrangian coherent structures have recently received increasing attention, mainly driven by advancements in Lagrangian flow measurement techniques (Haller, 2015; Hadjighasem et al., 2017). Lagrangian particle tracking (LPT), in particular, is widely used nowadays due to its ability to quantity fluid-parcel trajectories in three-dimensional volumes (Schanz et al., 2016).
On the determination of 3D position and orientation of spheroidal particles using defocusing and deep learning
Authors: Rossi Massimiliano
Published: September 2021

Tracking the 3D position of tracer particles or small objects like cells or unicellular organisms in miniaturized lab-on-a-chip or biomedical devices is complicated since it is often not possible in these setups to use multi-camera approaches. Most successful single-camera approaches for these applications are based on holography or defocusing. Holographic methods have been used to track complex objects such has bacteria (Bianchi et al. (2019)) and even to estimate their orientation (Wang et al. (2016)). However, these methods require a complex and expensive experimental setup which is not always available in research laboratories. On the other hand, defocusing methods work with conventional microscopic optics, are easy to implement, and have shown excellent results in 3D PTV experiments (Qiu et al. (2019)). One main drawback is that they normally work only with spherical and mono-dispersed tracer particles. A defocusing method that has potential to measure non-spherical particles is the General Defocusing Particle Tracking (Barnkob and Rossi (2020)) which is based on pattern recognition and can be conceptually extended to more complex tasks by extending the reference library of particle images, including not only spherical particles at different depth positions, but also non-spherical particles at different orientations. However, whether this approach could work in practice is still unknown. First, is the information contained in simple defocused images sufficient to reconstruct depth and orientation of non-spherical particles, and eventually under which circumstances? Second, how to practically collect the labelled reference images?
Color contamination matrix property assessment for improvement of colored smoke PIV
Authors: Murai Yuichi , Horimoto Yasufumi , Park Hyun Jin , Tasaka Yuji
Published: September 2021

A single-camera color PIV system that can acquire PIV data of three separated layers has been redesigned, purposing improvement of wind tunnel applicability. We target smoke image that has particle-per-pixel values higher than unity. The system constitutes of a high-power color-coding illuminator and a digital color high-speed video camera. RGB values in recorded image involves severe color contaminations due to five optical and digital sequences (Fig. 1). To quantify this, a snapshot calibration is proposed to describe the contamination matrix equation (Eq. (1)). Taking the inverse matrix (Eq. (2)) allows in-plane PIV in each color layer to be accurately implemented. We also derive mathematical limits to operate the colored smoke PIV, which is explained by the matrix property (Eq (3)). Feasibility of the proposed method has been demonstrated by application to a turbulent wake behind a Delta wing (Fig. 2) and also to a boundary layer flow along heated chocolate.
Uncertainty of PIV/PTV based pressure, using velocity uncertainty
Authors: Zhang Jiacheng , Bhattacharya Sayantan , Vlachos Pavlos
Published: September 2021

Pressure reconstruction from velocity measurements using particle image velocimetry (PIV) and particle tracking velocimetry (PTV) has drawn significant attention as it can provide instantaneous pressure fields without altering the flow. Previous studies have found that the accuracy of the calcualted pressure field depends on several factors including the accuarcy of the velocity measurement, the spatiotemporal resolutions, the method for calculating pressure-gradient, the algorithm for pressure-gradient integration, the pressure boundary condition, etc. Therefore, it is critical and challenging to quantify the uncertainty of the reconstructed pressure field. The recent development of the uncertainty quantification algorithms for PIV and PTV allows for the local and instantaneous uncertainty estimation of velocity measurement, which can be used to infer the pressure uncertainty. In this study, we introduce a framework that propagates the standard velocity uncertainty defined as the standard deviation of the velocity error distribution through the pressure reconstruction process to obtain the uncertainty of the pressure field. The uncertainty propagations through the calculation of the pressure-gradient and the pressure-gradient integration were modeled as linear transformations, which can reproduce the effects of the spatiotemporal resolutions, the numerical schemes, the integration algorithms, and the pressure boundary condition on the accuracy of the resulting pressure fields. The proposed uncertainty estimation approach also considers the effect of the spatiotemporal and componentwise correlation of the velocity errors in common PIV/PTV measurements on the pressure uncertainty.
Pressure from data-driven-estimated velocity fields using snapshot PIV and fast probes
Authors: Raiola Marco , Chen Junwei , Discetti Stefano
Published: September 2021

This work explores the use of data-driven techniques to retrieve time-resolved information from snapshot PIV by exploiting the information from synchronized high-repetition rate sensors measuring flow quantities in few points, and to compute from it the instantaneous pressure field leveraging the Navier-Stokes momentum equation of the flow. This work focus on a technique rooted in the Extended Proper Orthogonal Decomposition, which already proven good performances in estimating time-resolved velocity fields from a finite number of probes synchronized with field measurements. The performances of the technique and its robustness to noise are tested on 2 synthetic dataset, a laminar one and a turbulent one, and compared to the most commonly applied technique to retrieve time-resolved information from snapshot PIV which exploits Taylor’s hypothesis.
GANs-based PIV resolution enhancement without the need of high-resolution input
Authors: Güemes Alejandro , Sanmiguel Vila Carlos , Discetti Stefano
Published: September 2021

A data-driven approach to reconstruct high-resolution flow fields is presented. The method is based on exploiting the recent advances of SRGANs (Super-Resolution Generative Adversarial Networks) to enhance the resolution of Particle Image Velocimetry (PIV). The proposed approach exploits the availability of incomplete projections on high-resolution fields using the same set of images processed by standard PIV. Such incomplete projection is made available by sparse particle-based measurements such as super-resolution particle tracking velocimetry. Consequently, in contrast to other works, the method does not need a dual set of low/high-resolution images, and can be applied directly on a single set of raw images for training and estimation. This data-enhanced particle approach is assessed employing two datasets generated from direct numerical simulations: a fluidic pinball and a turbulent channel flow. The results prove that this data-driven method is able to enhance the resolution of PIV measurements even in complex flows without the need of a separate high-resolution experiment for training.
Super-resolution PIV using multi-frame displacement information
Authors: Yang Hua , Ouyang Zhenxing , Cao Yunkang , Yang Zhen , Yin Zhouping
Published: September 2021

High-resolution (HR) fluid-flow velocity information is important to reliably analyze fluid measurements in particle image velocimetry (PIV), such as the boundary layer and turbulent flow. Efforts in PIV to enhance the resolution of flow fields are mainly based on single-frame information, which follows the velocity field estimation and may influence the final reconstruction accuracy. In this study, we propose a novel super-resolution (SR) reconstruction technology from another perspective, which consists of two parts: a multi-frame imaging system and a Bayesian-based multi-frame SR reconstruction algorithm. First, a splitbased imaging system is developed to obtain particle image pairs with fixed displacements. Subsequently, we present a Bayesian-based multi-frame SR (BMFSR) reconstruction algorithm to obtain an SR particle image. Multi-frame particle images collected by the developed system are used as the input low-resolution images for the following novel SR reconstruction algorithm. Synthetic and experimental particle images have been tested to verify the performance of the proposed technology, and the results are compared with the traditional and advanced reconstruction methods in PIV. The results and comparisons show that the proposed technology successfully achieves good performance in obtaining finer particle images and a more accurate velocity field.
Data reconstruction of homogeneous turbulence using Lagrangian Particle Tracking with Shake-The-Box and machine learning
Authors: Kim Dong , Kim Kyung Chun
Published: September 2021

This paper proposes a data reconstruction of homogeneous turbulent flow combined machine learning (ML) approach using experimental Lagrangian Particle Tracking (LPT) data with Shake-The-Box (STB). The LPT with STB was adopted to measure a von Kármán flow with a homogeneous turbulent region in the center [1]. The STB results have been stored and a temporal filter using 3rd order B-splines has been applied with optimal weighting coefficients to be used as input for FlowFit data assimilation method [2]. FlowFit data was used as ground truth to train ML algorithm. The low-resolved data of the velocity and acceleration field was reconstructed using an Adaptive Neuro-Fuzzy Inference System (ANFIS) with the downsampled LPT data as an input to predict homogeneous turbulent flow [3]. The training process can be mathematically regarded as an optimization problem to determine the weighting factor.
Multi-spectral imaging for Thermochromic Liquid Crystal based Particle Image Thermometry: A proof of concept
Authors: Käufer Theo , Moller Sebastian , Rosenberger Maik , Notni Gunther , Cierpka Christian
Published: September 2021

In this contribution, a novel imaging approach for Thermochromic Liquid Crystal (TLC) based Particle Image Thermometry (PIT) is demonstrated. In contrast to state of the art approaches, a multi-spectral camera was used to record the color response of the Thermochromic Liquid Crystals seeding particles. An experiment with a transparent, water-filled, cylindrical cell as the central element was set up to investigate the novel approach. The temperature in the cell can be controlled by adjusting the temperature of the bottom and top plate. Calibration images at eleven different temperatures ranging from 18 ◦C to 21.6 ◦C, as well as images of a stable thermal stratification, were recorded. 90 percent of the calibration data was used to train a neural network (NN) to predict the temperature. The remaining 10 percent of the calibration data and the data of the stable thermal stratification were used to test the NN. The tests show that the deviation between predicted and ground truth temperature is mostly below 0.1 K and that the linear profile of the stable thermal stratification can be predicted with a maximum deviation of ≈ 0.15 K. This shows that multi-spectral imaging with neural networks for data processing is feasible and a promising concept.
Intermittency effects in single- and multi-phase flow and anomalous transport in heterogeneous porous media
Authors: Penko Zoë , Li Yaofa , Bolster Diogo , Christensen Kenneth T.
Published: September 2021

Multi-phase flow and transport in porous media is prevalent in a wide range of challenging fluid mechanics problems related to sustainability, energy, and the environment. Accurate prediction of the displacement and interaction of such flows is vital in addressing these problems. In particular it is critical to understand the small- or pore-scale flow and its spatial and temporal evolution, which can impact behaviors at system scales in a nontrivial manner. Intermittency is a phenomenon currently observed in numerical and experimental studies of single-phase flow (Anna et al., n.d.; Morales et al., n.d.), but the case of multi-phase flow has yet to receive much study due to challenges faced in both simulations and experiments. The underlying physics of spreading, mixing, and interfacial processes must be understood for accurate predictions of transport in multi-phase flow systems. Therefore, a comprehensive understanding of multi-phase flow at these very small scales is necessary in the development of accurate system-scale prediction models. We present results from a coordinated numerical and experimental study of intermittency effects over a range of viscous and inertial flow regimes in single- and multi-phase flows in 2D heterogeneous micromodels to quantify Lagrangian flow statistics to better inform pore-scale models. The applicability of different modeling frameworks such as the correlated-continuous time random walk is tested by studying statistics of particle trajectories obtained by particle tracking velocimetry (PTV) measurements and Lattice Boltzmann simulations from single- and multi-phase flows. The results make particular note of the influence of the pore Reynolds number (Re) and inertial effects on intermittency, and compare these effects in the two flow regimes.
PIV measurement of complex flow characteristics in open-cell metal foam replica
Authors: Kim Minsin , Kim Youngwoo , Hosseini Sajjad , Kim Kyung Chun
Published: September 2021

Time-resolved 2-D particle image velocimetry was used to study on turbulent flow characteristics inside an open-cell metal foam under the laminar and turbulent inlet conditions. A study on the effect of Reynolds number was conducted with different three channel Reynolds numbers, 1000, 5000 and 10000. Uniform upstream flow is divided by the pore network of metal foam and it is found that there are flow disturbances induced by metal foam structure even at a laminar inlet condition. It is confirmed that there is a similarity of the preferred flow path flows take regardless of Reynolds number.
An experimental approach to analyze aerosol and splatter formation in a dental practice
Authors: Mirbod Parisa , Haffner Eileen A. , Bagheri Maryam , Higham Jonathan E.
Published: September 2021

The flow velocity, trajectories, and size distribution of droplets produced during a dental scaling procedure using a Cavitron ultrasonic scalar (CUS) has been investigated by optical flow tracking velocimetry and shadowgraphy measurements. The droplet sizes are found to vary from 5 -500 µm; these correspond to droplet nuclei that could carry viruses. The droplet velocities also vary between 0.7 m/s and 1.3 m/s. These observations confirm the critical role of aerosols in the transmission of disease during dental procedures, providing invaluable knowledge for developing protocols and procedures to ensure the safety of both dentists and patients especially during COVID-19 pandemic.
Lagrangian Strain- and Rotation-Rate Tensor Evaluation Based on Multi-pulse Particle Tracking Velocimetry (MPTV) and Radial Basis Functions(RBFs)
Authors: Li Lanyu , Sellappan Prabu , Schmid Peter , Hickey Jean-Pierre , Cattafesta Louis , Pan Zhao
Published: September 2021

Physical conservation laws are inherently Lagrangian. However, analyses in fluid mechanics using the Lagrangian framework are often forgone in favor of those using the Eulerian framework. This is perhaps due to a lack of experimental techniques with high temporal and spatial resolution that track the movement of fluid tracers in a flow domain. The development of time-resolved Particle Tracking Velocimetry/Accelerometry (TR-PTV/A) that measures flows with high seeding density has made the use of the Lagrangian framework more accessible. A challenge facing PTV/A is the need for robust mesh-free numerical schemes that handle random particle locations. Such a scheme can be created with high-order accuracy using Radial Basis Functions (RBFs). RBFs allow direct evaluation of derivatives of vector and scalar fields at random locations with infinite-order smoothness. The current work uses RBF-based differential schemes to develop a post-processing tool for PTV/A data, which can accurately evaluate spatial derivatives directly from Lagrangian particle tracks. This RBF-based strain/rotation-rate tensor evaluation tool is validated with two and three-dimensional flows from analytical solutions and is then tested with experimental data measured by a multi-pulse PTV/A system.
experimental investigation on stall flutter over a vertically mounted rigid finite wing
Authors: Soares Renan Francisco , Karasu Ilyas , Ganapathisubramani Bharath
Published: September 2021

As stall flutter has relevant engineering implications, such as in blades of wind turbine and HALE (highaltitude long-endurance aircraft). This work presents the experimental investigation of rigid wing setup in a closed-circuit wind tunnel having 2.1 m × 1.5 m test section. The experimental campaign reached stable and symmetrical LCO within the freestream range from 9 m/s up to 14 m/s (1.69 × 105 < Re < 2.63 × 105 ). Two techniques were used for position tracking: one mechatronic and one image-based. The latter used ‘shakethe-box’ method applied to a body, which has proven a successful approach as a non-intrusive tool.
Large-scale structures of scalar and velocity in a turbulent jet flow
Authors: Reijtenbagh Jesse , Westerweel Jerry , Van de Water Willem
Published: September 2021

We study the relation between large-scale structures in the concentration field with those in the velocity field in a dye-seeded turbulent jet. The scalar concentration in a plane is measured using laser-induced fluorescence. Uniform concentration zones of an advected scalar are identified using cluster analysis. We simultaneously measure the two-dimensional velocity field using particle image velocimetry. The structures in the velocity field are characterized by finite-time Lyapunov exponents. The measurement of the scalarand velocity fields moves with the mean flow. In this moving frame, turbulent structures remain in focus long enough to observe well-defined ridges of the finite-time Lyapunov field. This field gauges the rate of point separation along Lagrangian trajectories; it was measured both for future and past times since the instant of observation. The edges of uniform concentration zones are correlated with the ridges of the past-time Lyapunov field, but not with those of the future-time Lyapunov field.
Ghost particle reduction in particle streak velocimetry
Authors: Tsalicoglou Christina , Roesgen Thomas
Published: September 2021

Ghost particles are ambiguities in the process of the 3D-reconstruction of seeding particles detected in short-exposure imaging for volumetric flow velocimetry. 3D Particle Streak Velocimetry (3D-PSV) relies on long-exposure images, where the pathlines of the seeding particles are imaged as streaks. In this work, we demonstrate the inherent suitability of 3D-PSV for ghost particle rejection by calculating the probability of ghost streak generation in different scenarios and comparing our results to simulations.
Wake behind circular cylinder excited by spanwise non-uniform disturbances
Authors: Kamiyama Takumi , Ino Mizuki , Yokota Yudai , Sakakibara Jun
Published: September 2021

We studied a modification of wake behind a circular cylinder using a plasma actuator. The plasma actuators were arranged in the spanwise direction of the cylinder to give temporal periodic disturbances having Strouhal number St = 0.18-2.3 with a burst ratio BR = 20 and 40%. The Reynolds number was set in a rage of Re = 4200 to 8400. Two types of plasma actuator were prepared; one is a single strip of the actuator placed at each side of the cylinder to give a spanwise uniform disturbance, and another is an array of small piece of actuators placed at the same location to create a spanwise non-uniform disturbance with temporal phase difference, φ = 0 or π, between adjacent electrodes. A conventional two-component PIV and stereo PIV was used to measure the flow field. Figure 1 shows the instantaneous spanwise component of vorticity at Re = 4200 evaluated by two-component PIV. Under no disturbance condition, the laminar shear layer extends straight to around x / d = 1.5 and then forms a wake vortex, as shown in Fig.1(a). In the case of spanwise non-uniform forcing with St = 1.09 and φ =π, rapid roll up of the initial shear layer leads to arrangement of wake vortices closer to the cylinder., as shown in Fig.1(b). With higher Strouhal number case with St = 1.09 and φ = 0, shown in Fig.1(c), a series of fine scale vortices are generated behind both side of the cylinder without forming regular Karman vortices. The spanwise non-uniform forcing was effective to suppress the formation of large scale vortices just behind the cylinder. Figure 2 shows surface of constant vorticity magnitude and vortex lines under St =1.09 and φ = π case. These were computed from a phase-averaged threecomponents velocity field evaluated by stereo PIV. The value of the surface was selected to display the boundary layer formed on the cylinder, and the vortex lines are selected to visualize the vortex structure formed in the following shear layer. A bundle of vortex lines are shaped in a wavy pattern along spanwise direction with 180 degrees out of phase to the adjacent bundle upstream of downstream. This structure, so called ‘chain-line fence structure’ was already found in planar free shear layer [Nygaard, K.J. and Glezer, A., 1990, Phys. Fluids A, 2, 461] and planar jet [Sakakibara, J., Anzai, T., 2001, Phys. Fluids, 13, 1541], but it became evident to create it in the wake of circular cylinder in this study.
Measurement of energy spectrum by using 100 eyes Tomographic PIV
Authors: Harada Yuki , Saiga Kazuto , Sakakibara Jun
Published: September 2021

PIV is one of the methods to measure velocity in a flow field, but its dynamic velocity range is narrower than other flow velocimeter. This disadvantage is particularly apparent in measurements of spectrum in turbulent boundary layers, where the higher wave number side of the spectrum cannot be measured with high accuracy.
In this study, we captured images of the same particle in the flow field from many different direction simultaneously, and reduced the measurement error of the particle displacement by averaging the acquired particle positions, so called ‘Multiple Eye PIV’ [Maekawa, A., Sakakibara, J., 2018, Meas. Sci. Tech., 29, 064011]. We applied this method to obtain the energy spectrum in a turbulent pipe flow aiming for resolving higher wave number. Particle images were captured by a single high-speed CMOS camera (Fastcam Nova S6, 6000 fps, Photron) through a mirror array consists of 110 flat mirrors arranged in the shape of an axisymmetric ellipsoid (Fig.1), as shown in Fig.2. The images were evaluated by Tomographic PIV method to resolve three-dimensional velocity field.
Fig.3 shows energy spectrum in a pipe measured by Tomographic-PIV with number of mirrors, N, up to 100 in addition to the 2D2C-PIV with a single mirror. Although the spectrum curve for the result of Tomographic-PIV begins to depart from the reference curve at wavenumber beyond 10-1 , such wavenumber grows as N increases, and consequently the plateau of the curve appeared at lower energy. Such a downward shift of the plateau is expected due to the improvement of the dynamic velocityrange, which is approximately one order in energy, i.e. three times in velocity, found between N=4 and 100. Note that the cases of N=4 and 40 loses the dynamic range against the 2C2D-PIV case. From the above, we can summarize that the advantage of Multiple Eye PIV over the 2C2D-PIV is effective when the number of mirrors is more than 40.
In this experiment, the issue is that particles images flickered. In order to resolve this issue, we tried to use fluorescent particles, and obtained a clear particle images in the following experiment. We are now analyzing whether the energy spectrum can be measured with higher accuracy due to improved resolution of the particles.
Large Scale Infrared-Based Remote Sensing of Turbulence Metrics in Surface Waters: Going Beyond Mean Flow
Authors: Schweitzer Seth Avram , Cowen Edwin Alfred
Published: September 2021

In recent years field-scale applications of image-based velocimetry methods, often referred to as large scale particle image velocimetry (LSPIV), have been increasingly deployed. These velocimetry measurements have several advantages—they allow high resolution, non-contact measurement of surface velocity over a large two dimensional area, from which the bulk flow can be inferred. However, visiblelight LSPIV methods can have significant limitations. The water surface often lacks natural features that can be tracked in the visible and generally requires seeding with tracer particles, which creates concerns regarding the fidelity with which tracer particles track the flow, and introduces challenges in achieving sufficient and uniform seeding density, in particular in regions with appreciable velocity accelerations such as turbulence. In LSPIV, image collection is generally limited to daylight hours, and can suffer from non-uniformity of illumination across the camera’s field of view. Due to these issues LSPIV often requires spatio-temporal averaging, and as a result is generally able to extracting the mean, but not the instantaneous, velocity field, and hence is often not a suitable tool for calculating turbulence metrics of the flow.
Fluorescent PIV using Atomized Liquid Particles
Authors: Acharya Adit S. , Lowe K. Todd , Ng Wing F.
Published: September 2021

It is shown that aerosolized fluorescent particles generated using a Venturi-type atomizer, from a solution of fluorescent Kiton Red 620 dye in a water/glycol fluid, provide effective flow seeding for fluorescent PIV. The atomized liquid particles were found to be of acceptable size for PIV purposes, with 92% of detected particles by number concentration measuring < 1 μm in diameter. A PIV application was conducted in a wind tunnel (freestream velocity U∞ = 27 m/s), using the particles for measurement of the boundary layer flow approaching a forward-facing step (approach boundary layer momentum thickness Reynolds number of Reθ = 5930), to identify potential benefits in near-wall regions normally affected by unwanted laser reflections from tunnel surfaces. Particles were generated from solutions with dye molar concentrations of 2.5 × 10−3 and 1.0 × 10−2 mol/L, and PIV images were obtained for both elastic Mie scattering and filtered, Stokes-shifted fluorescent light. Raw images indicate that the fluorescence yield of the 1.0 × 10−2 mol/L solution provides PIV images with high contrast, even in the near-surface regions where Mie scattering images are highly affected by surface reflections. Boundary layer profiles are processed in the adverse pressure gradient region leading up to the forward-facing step, where the fluorescent PIV performed comparably to the most optimized Mie scattering PIV; both obtained data as near to the wall as 30 μm, or 2 viscous wall units in our flow of interest. These results indicate that the new seeding method holds excellent promise for near-surface measurement applications with more complicated three-dimensional geometries, where it is impossible to arrange PIV cameras to reject surface-scattered light.
TrackFit: Uncertainty Quantification, Optimal Filtering and Interpolation of Tracks for Time-Resolved Lagrangian Particle Tracking
Authors: Gesemann Sebastian
Published: September 2021

Advanced Lagrangian Particle Tracking methods (such as the STB algorithm (Schanz et al. 2016)) are a very useful tool for uncovering properties of flow. As a measurement technique, the results of such methods are perturbed by different sources of errors and noise. This work addresses the problem of optimal filtering of particle tracks as well as estimating uncertainties of derived quantities such as location, velocity and acceleration of observed particles. The behavior and performance of this new filtering method (“TrackFit”), first introduced at Gesemann et al. (2016) is analyzed and compared to the Savitzky–Golay filter (Savitzky and Golay (1964)) which is commonly used for these purposes. The optimal choice of parameters of this filtering method as well as the uncertainty quantification of the reconstructed tracks can be extracted from a spectral analysis of the recorded raw particle tracking data. This is in contrast to a Savitzky–Golay filter where the choice of parameters might often be driven by experience and gut feeling. Estimating the power spectral density (PSD) of the particle trajectory signals for the purpose of optimal filtering parameter selection represents a challenge due to possibly short trajectory signals. In the following work we will present a method for PSD estimation that is applicable in this scenario. In addition, we show that regardless of the choice of Savitzky–Golay filter parameters, the resulting filter will not approximate the ideal noise reduction filter well unlike the “TrackFit” described in this work.
Abstracts of poster presentations at the 2021 virtual annual of the Canadian Society for Pharmaceutical Sciences.
Authors: Warman Kristine
Published: September 2021

In 2021, the Canadian Society for Pharmaceutical Sciences (CSPS) partnered with he Pharmaceutical Society of Japan (PSJ) and the Canadian Chapter of Controlled Release Society (CC-CRS) and presented its annual matting in virtual style. Keynote speakers included Professor Michael Houghton – 2020 Nobel Laureate, Director of Li Ka Shing Applied Virology Institute (LKSAVI), Professor, Department of Medical Microbiology & Immunology, University of Alberta and Professor Yoshiharu Matsuura, Director, Center for Infectious Diseases Education and Research (CIDER), Osaka University, Japan.
Supplementation of corn tortilla with freeze-dried jumbo squid muscle flour: physicochemical properties and microbiological stability during storage
Authors: Heredia-Sandoval Nina Gisella , Santiaguin-Padilla Aaron Jonary , Granados-Nevarez María del Carmen , Scheuren-Acevedo Susana María , Islas-Rubio Alma Rosa , Mazorra-Manzano Miguel Angel , García-Sánchez Guillermina , Ramírez Suárez Juan Carlos
Published: September 2021

Corn tortilla is one of the most consumed foodstuffs in Latin America, representing a good nutrients source, although deficient in some essential amino acids. Jumbo squid (Dosdicus gigas) muscle possesses high-quality protein, useful for tortilla supplementation. Our objective was to elaborate corn tortillas supplemented with jumbo squid muscle flour (JSMF), using composite corn flours containing JSMF (2.5 and 5.0%), to improve their nutritional quality without affecting their physicochemical/sensory properties and storage stability. Supplementation with 5% JSMF increased (P<0.05) tortilla protein level, and the essential amino acids versus the control. The 2.5% JSMF tortillas were tasteful and acceptable (P≥0.05) as the control. JSMF addition showed an antimicrobial effect on mesophilic and psychrophilic bacteria; however, yeast and moulds grew beyond the permissible limit at day 5 of storage. JSMF addition did not affect (P≥0.05) the cutting force, with all tortillas tending to become harder to roll without cracking as storage elapsed. Tortilla storage stability (supplemented or not) was 3 days at 2–4 °C. Results suggest the feasibility of adding JSMF to corn tortilla, improving its nutritional characteristics without markedly affecting other parameters.
Can bowel necrosis be predicted with inflammatory markers in incarcerated inguinal hernia?
Authors: AKIN Tezcan , ÖZDEN Sabri , BİRBEN Birkan , ERKUŞ Yasin , YÜKSEL Bülent Cavit , TİKİC Deniz , BERKEM Hüseyin , AKIN Merve , ER Sadettin
Published: September 2021

Aim: To evaluate the predictive or diagnostic value of inflammatory markers in the presence of bowel necrosis in patients with an incarcerated inguinal hernia.

Material and Methods: The sample consisted of 246 patients that were admitted to the Emergency Service of Ankara Numune Training and Research Hospital and were operated on between January 2013 and January 2018 with a diagnosis of incarcerated inguinal hernia (IIH). The electronic patient records were screened to obtain the blood test results pertaining to lymphocyte count, neutrophil count, neutrophil/lymphocyte ratio (NLR), red cell distribution width (RDW), platelet count, and RDW/platelet ratio; surgical notes concerning resection status and inguinal hernia type; and demographic data. The patients included in the study were divided into two groups as those that had received a bowel resection and those that had not undergone this procedure.

Results: Of the 246 patients, 159 (65%) were male and 87 (35%) were female. The median age (interquartile range) was 71 (66-78) years and 62 (50-74) years in the resection (n= 23) and non-resection (n= 223) groups, respectively. There was a statistically significant difference between the two groups in terms of age (p= 0.004), neutrophil count (0.001), NLR (p= 0.000), and lymphocyte count (0.000). The multivariate analysis revealed that NLR (odds ratio= 1.113, 95% confidence interval value: 1.055-1.175, and p= 0.000) was individually, independently and significantly associated with bowel resection.

Conclusion: Considering that it is possible to prevent the strangulation of a hernia in patients with IIH, urgent surgery is recommended for patients with an NLR of > 6.5.
Evaluation of laboratory parameters in inflammatory myositis
Authors: PAMUKCU Melih , İZCİ DURAN Tuğba
Published: September 2021

Aim: Polymyositis (PM) and dermatomyositis (DM) are the two most common forms of idiopathic inflammatory myositis (IIM) and they are generally rare diseases. We evaluate the relationship of C-reactive protein (CRP)/albumin ratio (CAR), neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio and other inflammatory markers with IIM.

Material and Methods: 30 patients and 30 healthy volunteers aged >18 years were included. Demographic data such as age, gender were recorded. CRP, erythrocyte sedimentation rate (ESR), albumin values, leukocyte, neutrophil, lymphocyte, platelet counts were determined.

Results: The median (IQR) age of the patients and healthy volunteers were 46 (38-60) years and 45 (42-52) years, respectively. 50% of the patients had a diagnosis of DM and 50% of them had a diagnosis of PM, and the median (IQR) duration of disease was 4 (0.5-13) years. The median value of CAR was 3.6 (1.0-5.1) in the patient group and 0.3 (0.1-0.6) in the control group; the NLR was 3.4 (2.3-4.4) in the patient group, 1.8 (1.6-2.1) in the control group; PLR was 223 (157-249) in the patient group, 107 (100-125) in the control group and CAR, NLR, and PLR values between the groups were significantly different (p