bluuebunny/crossref_metadata_2025 huggingface dataset:
Exit Plane Velocity Profiles and Boundary Layer Similarity on a Forward-Facing Cylinder Issuing a Jet Into a Counterflow
Authors: Vaccaro John C. , Rooney David M. , Balestrieri Thomas , Lipani Michael C. , Mikhaylov Yakov R.
Published: December 2016

An experimental study was undertaken to examine two phenomena associated with a jet issuing from a forward-facing circular cylinder (with a length to outer radius ratio of 6.8) into a counterflow: (1) the effect of the counterflow on the internal velocity profile near the injector exit, and (2) the combined jet and counterflow influence on the external surface boundary layer profiles. Wind tunnel experiments, utilizing hot-wire anemometry, were conducted at very low jet-to-counterflow velocity ratios between 0 and 0.41 and Reynolds numbers based on cylinder outer diameter of 2.6×104 and 5.2×104. It was found that the flow at the internal location was negligibly affected by the counterflow, with the profiles exhibiting typical turbulent pipe flow behavior. However, close to the injector exit plane, the counter-flow accelerated the exiting jet in an annular region adjacent to the cylinder inner wall, creating a high velocity region which reversed direction upon exiting. The exit flow reversal around the lip of the cylinder was manifested downstream as an addition of momentum to the flow field. Boundary layer measurements were taken at seven streamwise locations along the upper surface of the cylinder. A dimensionless parameter constructed from both a traditional flat plate turbulent boundary layer scaling and a geometric curvature ratio was used to plot all data, which collapsed to a single curve at all locations in the absence of a jet, while in the presence of the jet, the only differences in the profiles were close to the surface. Independently of jet-to-counterflow velocity ratio, the boundary layer on the cylinder was seen to grow in the streamwise direction at a rate proportional to x25 rather than x45 as occurs with a turbulent boundary layer on a flat plate, even though the boundary layer height to curvature ratio was relatively low (≈ 1), and hence would have been expected to approximate flat plate behavior.
Direct Numerical Simulation of Turbulent Flow and Aeroacoustic Fields Around an Airfoil Using Lattice Boltzmann Method
Authors: Kusano Kazuya , Yamada Kazutoyo , Furukawa Masato , Moon Kil-Ju
Published: December 2016

The paper presents a result of the direct numerical simulation with the lattice Boltzmann method which was conducted for quantitative prediction of turbulent broadband noise. For better prediction of broadband noise with high frequency, which is generally generated in high Reynolds number flows, not only high grid resolution is required for a flow simulation to capture very small eddies of the sound source inside the turbulent boundary layer, but also the computation of acoustic field is often needed. In such case, the direct simulation of flow field and acoustic field is straightforward and effective.

In this study, the direct simulation with the lattice Boltzmann method was conducted for a flow around the NACA0012 airfoil with the Reynolds number of two hundred thousand. In order to efficiently simulate this high Reynolds number flow with the LBM, the multi-scale approach was introduced in conjunction with the Building-cube method, while keeping the advantage of the LBM with the Cartesian mesh. At the condition with angle-of-attack of 9 degrees, a laminar separation bubble arises on the suction surface near the leading-edge and the suction boundary layer downstream of it is turbulent due to the separated-flow transition. As a result, turbulent broadband noise is generated from the boundary layer over the airfoil with the separated-flow transition. In the paper, as for prediction of such broadband noise, the computed frequency spectrum of far-field sound is validated to agree with the experimental result. In addition, through the detailed analyses of turbulent properties of the turbulent boundary layer on the suction surface, the validity of the present direct numerical simulation is demonstrated.
Numerical Simulation and Test Research on the Wear of Back Blades in Slurry Pumps
Authors: Tao Yi , Yuan Shouqi , Liu Jianrui , Zhang Fan , Tao Jianping
Published: December 2016

Back blades are usually assembled on the outside surface of impeller back shroud as a sealing device in centrifugal slurry pumps. The presence of solid particles in slurry leads to an obvious problem about the abrasion of the flow components of pump. Especially, the life of sealing devices, like the back blades, the oil seals and the shaft sleeve, is only a quarter or less of other components. Hence, an important engineering significance lies in the research on the abrasion of back blades.

In this paper, a single-stage horizontal type centrifugal pump was chosen as the main study model. The 3D model of the entire flow field was meshed by hexahedral structured grids. Based on the Particle model, which is an Eulerian multiphase method, the internal two-phase flow in the centrifugal slurry pump was simulated by using ANSYS CFX software. Six optimized design cases with the variation of back blades were analyzed to study the influence of vane profile and blade number of back blades on the abrasion characteristic and sealing performance. The main conclusions obtained are as follows: the volume fraction of solid phase achieved by simulation is in good agreement with the test results; the effect of vane profile on the flow of particles in the passages and the pressure on the seal is small; the usage of less back blade number will lower the flow constraint of blades on the particles and increase the area of axial vortex in each single passage, which means that the impact velocity of particles towards the pressure side grows and the pressure on the seal increases significantly. Based on the simulation mentioned above, two better cases were selected and manufactured for trial. Then, a wear test rig was set up to study the wear pattern of impeller during the operation of pump. Through the comparison of these two impellers after the wear test, it is found that: the back blades with the back forward shape can effectively reduce the abrasion of back blades at the pressure sides near the trailing edge; thickening the trailing edge of back blades to increase the life of back blades is feasible in practical application. The optimization design of back blades was preliminarily achieved which could provide some reference for the optimization design of back blades in centrifugal slurry pumps.
Numerical Analysis of Fluid Flow Through an Electrical Submersible Pump for Handling Viscous Liquid
Authors: Siddique Md. Hamid , Manayilthodiyil Sanoop , Husain Afzal , Samad Abdus , Kenyery Frank
Published: December 2016

Generally, artificial lifts to pump crude oil having a high viscosity from wellbores using an electrical submersible pump (ESP) are not efficient. The present study consists of a numerical approach to understand the effect of fluid viscosity and surface roughness of the flow passage on the performance of an ESP. A three-dimensional numerical analysis was carried out using Reynolds-averaged Navier-Stokes equations at different off-design conditions. The standard k-ε turbulence model was used for the steady incompressible flow. Water and crude oils having different viscosities were used as working fluids and numerical analyses were made by varying surface roughness of the flow passage. Although there was a sharp drop in the efficiency with the increase in surface roughness, but the combined effect of viscosity and surface roughness showed an increase in efficiency up to a certain fluid viscosity.
Computational Fluid Dynamic Analysis of a Blood Pump: An FDA Critical Path Initiative
Authors: Nassau Christopher J. , Wray Timothy J. , Agarwal Ramesh K.
Published: December 2016

Computational Fluid Dynamics (CFD) has become a routine tool in recent times for use in blood-contacting medical device design and analysis, such as prosthetic heart valves and ventricular assist devices (VADs). While CFD can aid in design by decreasing the need for expensive prototyping and iterative laboratory testing, standardizations are not currently available for CFD to be used for medical device safety analysis at the preclinical stage. To address this, the U.S. Food and Drug Administration (FDA)’s Center of Devices and Radiological Health (CDRH) has sponsored CFD “round-robins.” This paper focuses on Computational Round Robin #2 - Model Blood Pump. The exact geometries, flow conditions and fluid characteristics for the CFD analysis have been supplied to the participants. In the CFD analysis presented in this paper, a rotating fluid zone around the pump impeller was used to avoid the complexities of a dynamic mesh. The rotating fluid zone was modeled by including the centrifugal and Coriolis forces in the Navier-Stokes equations. The Shear Stress Transport (SST) k-ω turbulence model was used and the steady-state solutions for the desired flow conditions were calculated. Current experimental data is still being collected by FDA for the flow conditions given in the study. However, some of the pump operating characteristics are available from work of other investigators and are used to validate the CFD results.
Dielectric Barrier Discharge Actuators to Control Goertler Vortices on a Swept Wing
Authors: Kumar Vaibhav , Thorell Nikolaus , Shukla Dhwanil , Komerath Narayanan
Published: December 2016

Narrowband excitation of fin buffeting is known to exist on several modern aircraft configurations at high angles of attack. For a fixed angle of attack and model geometry, narrowband peak frequency is a linear function of freestream speed. Under these conditions, counter-rotating vortex pairs conforming to the Goertler vortex mechanism are known to develop and amplify in the flowfield over the wings. This phenomenon is explored for relevance to reverse flow over rotor blades at high speeds as well. A 42-degree delta wing with rounded leading edges is used in a low-speed wind tunnel to confirm the phenomenon. The presence of a non-zero yaw angle can increase the strength of the Goertler vortices and also change the location of maximum intensity. Small fences on the surface have been shown to eliminate these narrow-band fluctuations. Dielectric Barrier Discharge plasma actuators offer a possible means to eliminate the narrowband excitation without obtrusive surface fences. An array of such actuators is used to generate counter-rotating vortices. Incense smoke entrained into the flow is illuminated with a laser sheet from a laser pointer. Video images are used to capture velocity in the potential flow region around the vortices. The induced velocity is used to calculate vortex strength. Scaling laws are used to estimate the frequency of the actuators, as well as the magnitude of the velocity. The scaling estimation shows that a plasma actuator is viable for model-scale configurations. Continuing experiments for the final paper plan to apply the actuator under delta wing high angle of attack operation.
Experimental Evaluation of Dual-Opposed Jet Mixer Pump Performance for Slurry Mixing
Authors: Bamberger Judith Ann , Enderlin Carl W.
Published: December 2016

Million-gallon double-shell tanks at Hanford are used to store transuranic, high-level, and low-level radioactive wastes. These wastes consist of a large volume of salt-laden solution covering a smaller volume of settled sludge primarily containing metal hydroxides. These wastes will be retrieved and processed into immobile waste forms suitable for permanent disposal. Retrieval is an important step in implementing these disposal scenarios. The retrieval concept evaluated is to use submerged dual-nozzle jet mixer pumps with horizontally oriented nozzles located near the tank floor that produce horizontal jets of fluid to mobilize the settled solids. The mixer pumps are oscillated through 180° about a vertical axis so the high velocity fluid jets sweep across the floor of the tank. After the solids are mobilized, the pumps will continue to operate at a reduced flow rate producing lower velocity jets sufficient to maintain the particles in a uniform suspension (concentration uniformity).

Several types of waste and tank configurations exist at Hanford. The jet mixer pump systems and operating conditions required to mobilize sludge and maintain slurry uniformity will be a function of the waste type and tank configuration. The focus of this work was to conduct a 1/12-scale experiment to develop an analytical model to relate slurry uniformity to tank and mixer pump configurations, operating conditions, and sludge properties.

This experimental study evaluated concentration uniformity in a 1/12-scale experiment varying the Reynolds number (Re), Froude number (Fr), and gravitational settling parameter (Gs) space. Simulant physical properties were chosen to obtain the required Re and Gs where Re and Gs were varied by adjusting the kinematic viscosity and mean particle diameter, respectively. Test conditions were achieved by scaling the jet nozzle exit velocity in a 75-in. diameter tank using a mock-up of a centrally located dual-opposed jet mixer pump located just above the tank floor.

Concentration measurements at sampling locations throughout the tank were used to assess the degree of uniformity achieved during each test. Concentration data was obtained using a real time in-situ ultrasonic attenuation probe and post-test analysis of discrete batch samples. The undissolved solids concentration at these locations was analyzed to determine whether the tank contents were uniform (≤ ±10% variation about mean) or nonuniform (> ±10% variation about mean) in concentration. Concentration inhomogeneity was modeled as a function of dimensionless parameters. The parameters that best describe the maximum solids volume fraction that can be suspended were found to be 1) the Fr based on nozzle average discharge velocity and tank contents level and 2) the dimensionless particle size based on nozzle diameter. The dependence on the jet Re does not appear to be statistically significant.
Particle Tracking Velocimetry (PTV) Measurement of Abrasive Microparticle Impact Speed and Angle in Both Air-Sand and Slurry Erosion Testers
Authors: Mansouri Amir , Arabnejad Khanouki Hadi , Shirazi Siamack A. , McLaury Brenton S.
Published: December 2016

Solid particle laden flows are very common in many industries including oil and gas and mining. Repetitive impacts of the solid particles entrained in fluid flow can cause erosion damage in industrial equipment. Among the numerous factors which are known to affect the solid particle erosion rate, the particle impact speed and angle are the most important. It is widely accepted that the erosion rate of material is dependent on the particle speed by a power law Vn, where typically n = 2–3. Therefore, accurate measurements of abrasive particle impact speed and angle are very important in solid particle erosion modeling. In this study, utilizing a Particle Image Velocimetry (PIV) system, particle impact conditions were measured in a direct impinging jet geometry. The measurements were conducted with two different test rigs, for both air-sand and liquid-sand flows. In air-sand testing, two types of solid particles, glass beads and sharp sand particles, were used. The measurements in air-sand tests were carried out using particles with various sizes (75, 150, and 500 μm). Also, submerged testing measurements were performed with 300 μm sand particles. In the test conditions, the Stokes number was relatively high (St = 3000 for air/sand flow, St = 27 for water/sand flow), and abrasive particles were not closely following the fluid streamlines. Therefore, a Particle Tracking Velocimetry (PTV) technique was employed to measure the particle impact speed and its angle with the target surface very near the impact. Furthermore, Computational Fluid Dynamics (CFD) simulations were performed, and the CFD results were compared with the experimental data. It was found that the CFD results are in very good agreement with experimental data.
Performance Evaluation of a Small Darius Wind Turbine Installed at Duckjeok Island in Korea
Authors: Lee Sang-Moon , Jang Choon-Man
Published: December 2016

Present paper describes performance on the small Darius wind turbine installed at the Duckjeok island in Korea. The turbine performance is evaluated using experimental measurements and numerical simulation. To determine the energy production of the turbine using experimental measurement, the wind turbine has been designed and installed at the Duckjeok island located in Korea. Local real-time wind conditions, local wind velocity, wind direction, ambient air temperature and atmospheric pressure are stored in a computer by data acquisition system with the turbine performance in real time. Numerical simulation using commercial code of SC/Tetra is employed in the present study. SST turbulence model is introduced to estimate the eddy viscosity. The reliability and efficiency of the numerical model have been confirmed through the grid dependency test and comparisons with the results of experimental measurement. Throughout the experiments and numerical simulation on the energy production of the turbine, relatively good agreement on the turbine performance is obtained. The detailed flow field inside the turbine blades is analyzed and discussed.
Uncertainty Quantification of Low Void Fraction Measurements Using Wire-Mesh Sensors in Horizontal Air-Water Flows
Authors: Lessard Étienne M. , Bowden Robert C. , Yang Sun-Kyu
Published: December 2016

The need for a revised methodology and uncertainty quantification for wire-mesh sensor void fraction measurements in horizontal low void fraction flow conditions was identified. Two-phase flow measurements were performed at a low-pressure, adiabatic and horizontal flow loop using wire-mesh sensors over a range of water superficial velocities from 3.5 to 5.5 m/s, air superficial velocities from 0.05 to 0.9 m/s and volumetric void fractions from 1 to 16% Using this proposed analysis, a corrected trend with average percent differences of 36, 21 and 6% was obtained for the low, medium and high gas flow rate cases, respectively, when comparing the wire-mesh sensor void fractions to two-phase pipe flow models. By combining these measurements of the void fraction with those of the interfacial velocity, the gas superficial velocity was calculated based on the physical theory, and compared to the superficial velocity measured by the flowmeters for validation purposes. An estimation of the uncertainty of these parameters showed that most of the measured parameters agreed reasonably with physical theory within 20%.
Global and Local Measurements and Proper Orthogonal Decomposition of a Swirling Conical Liquid Sheet
Authors: Choudhury Pretam K. , Davanlou Ashkan , Castillo Orozco Eduardo , Kumar Ranganathan
Published: December 2016

In this work, ultra-high speed imaging of conical liquid sheets allows for non-invasive measurements of both global and local features of a swirling conical liquid sheet. The breakup of the swirling conical liquid sheet is visualized and the interface tracked between the conical liquid sheet and the ambient air. The applied experimental technique and the image processing technique capture planar images that are capable of tracking the dynamic behavior of the conical liquid sheet. Cone angle is shown to increase up to a critical Weber Number. The film length is obtained by identifying singular points in the signal response of the radial fluctuations. The results of the proper orthogonal modes indicate the existence of traveling waves on the interface of the swirling conical liquid sheet. Wavelength measurements of the traveling waves are comparable with linear instability analysis.
Characterization of the Custom-Designed, High Reynolds Number Water Tunnel
Authors: Farsiani Yasaman , Elbing Brian R.
Published: December 2016

This paper reports on the characterization of the custom-designed high-Reynolds number recirculating water tunnel located at Oklahoma State University. The characterization includes the verification of the test section design, pump calibration and the velocity distribution within the test section. This includes an assessment of the boundary layer growth within the test section. The tunnel was designed to achieve a downstream distance based Reynolds number of 10 million, provide optical access for flow visualization and minimize inlet flow non-uniformity. The test section is 1 m long with 15.2 cm (6-inch) square cross section and acrylic walls to allow direct line of sight at the tunnel walls. The verification of the test section design was accomplished by comparing the flow quality at different location downstream of the flow inlet. The pump was calibrated with the freestream velocity with three pump frequencies and velocity profiles were measured at defined locations for three pump speeds. Boundary layer thicknesses were measured from velocity profile results and compared with analytical calculations. These measurements were also compared against the facility design calculations.
Flow Analysis and Design Improvement of a Heat Sink of an Integrated Starter Generator
Authors: Song Sangwoo , Hur Nahmkeon , Kwon Jeongki
Published: December 2016

Due to the limitation in volume and size of vehicles’ integrated starter generators (ISGs), an effective cooling mechanism has to be considered while designing the ISGs. The main purpose of this research is to improve the fins of heat sink design of the ISG to enhance the cooling performance and fan efficiency. To do this, conjugate heat transfer simulations have been performed using the realizable k-ε turbulence model. Also, the MRF method is employed for simulation of the rotating parts. Base on the analysis of the simulation result of the baseline model, the modified models are suggested and investigated. The rotation speed of the fan is 2000 rpm and the number of blades is 11 and 9 for the front and rear fans, respectively. By assuming that the flow in narrow gap between the rotor and stator is negligible, only the rear part which includes the heat sink is simulated. Firstly, conjugate heat transfer simulation is conducted for the baseline model and the heat transfer characteristics are observed. Then, from the observation, modified heat sink model with wider fin spacing is suggested and compared. In order to have more uniformly distributed flow field, a heat sink model with radially arranged fins is also made and simulated. As a result, it is concluded that increasing the air passages between the fins increases the heat transfer. In addition, it is observed that the optimized fan had better performance. Furthermore, radial fin structure is turned out to have advantage for cooling compare to the original heat sink structure. In a radial model, more uniform distribution of the flow is observed, both of flowrate and fan efficiency are higher and temperature of the coil is lower.
PIV Uncertainty: Computational and Experimental Evaluation of the Peak Ratio Method
Authors: Pothos Stamatios , Boomsma Aaron , Troolin Dan , Bhattacharya Sayantan , Vlachos Pavlos
Published: December 2016

Uncertainty quantification for planar PIV remains a challenging task. In the present study, we assess three methods that were recently described in the literature: primary peak ratio (PPR), mutual information (MI), and image matching (IM). Each method was used to calculate the uncertainty in a synthetic turbulent boundary layer flow and an experimental jet flow. In the experimental case, two PIV systems with common fields of view were used — one with a high dynamic range (which was considered as the true solution) and another with a magnification ratio of about four times less (which was considered the measurand). The high resolution PIV system was verified by comparing velocity records at a point with an LDV measurement system. PIV processing was performed with PRANA and Insight4G. In regards to the experimental flow, the PPR method performed best, followed by mutual information, and lastly image matching. This was due to better responses by PPR and MI of uncertainty to the spatially varying error distribution. Similar conclusions were made with respect to the synthetic test case.
The pursuit of normal reference values of pancreas stiffness by using Acoustic Radiation Force Impulse (ARFI) elastography.
Authors: Zaro Razvan , Lupsor-Platon Monica , Cheviet Alexandre , Badea Radu
Published: December 2016

Aim: The purpose of this study is to evaluate pancreatic stiffness by ARFI abdominal elastography. In the current literature, there are relatively few studies that have assessed the clinical utility of this technique. Material and method: A number of 37 healthy subjects were included. The data were collected in a prospective manner and afterwards included in an observational, analytical and longitudinal study. Subsequently viewing the pancreatic parenchyma in bidimensional mode (2D-US) mode, 10 shear wave velocity (SWV) measurements for each segment: head, body and tail were performed. Statistical analysis by regression models targeted also the possible influence of other factors in assessing SWV. A comparative analysis was performed regarding the statistical significance of 5 versus 10 SWV measurements for each segment. Results: The pancreas was entirely evaluated in all subjects. The mean SWV from the entire parenchyma was 1.216 m/s±0.36 and between the three segments SWV were similar (head: 1.224 m/s, body: 1.227 m/s and tail: 1.191 m/s). A ratio of the IQR/Median >0.4 was interpreted as statistically invalid, relevant data being highlighted in the percentage of 83.78% for the head of the pancreas, 78.37% for the body, and 67.56% at the caudal level. Significant correlations were observed between the data (mean and median SWV) provided by the group with 5 measurements of the SWV versus the standard group: 93.9% for the head, 96.6% for the body, and 98.7% accordingly to the tail. Conclusions: SWV determination by percutaneous approach represents a useful imaging method for evaluating pancreatic stiffness, of course within these limitations. Because we did not observe statistically significant differences between the results obtained by 5 or 10 measurements, we suggest that it would be sufficient to perform only five measurements of the SWV per pancreatic segment. The data obtained in the normal pancreas could be used in future comparative assessments regarding the inflammatory or tumoral pathology of the pancreas.
The impact of microbubble-enhanced therapeutic ultrasound combined with prothrombin on microwave ablation in the rabbit liver.
Authors: Shi Ying , Liu Xinyue , Luo Zhenli , Gu Fen , He Jianguo , Yan Ping , Zhang Junwang , Zhou Xiaodong
Published: December 2016

Aim: This study aimed to investigate the effect of microbubble-enhanced ultrasound (MEUS) combined with prothrombin on regional hepatic circulation and microwave ablation (MWA) in rabbit livers. Materials and methods: High-pressureamplitude therapeutic ultrasound (TUS) was used to treat 52 surgically exposed livers of healthy New Zealand rabbits: 13 livers were treated with MEUS alone, 13 with MEUS and prothrombin (PMEUS), 13 with ultrasound plus normal saline and 13 with ultrasound plus prothrombin as controls. Contrast-enhanced ultrasound (CEUS) imaging was performed on the exposed livers before and after treatment, and acoustic quantification was done to assess liver perfusion. Then, the liver was divided into two parts, one was used for pathologic examination and the other was ablated with microwave (MWA) and then processedfor pathologic examination. Results: The CEUS images and Peak value after treatment in the PMEUS group were significantly reduced as compared to the remaining 3 groups (p<0.05). Occasional piecemeal hemorrhage was evidenced in the pathological examination in the MEUS group. Obvious cellular degeneration and necrosis with thrombosis were observed in the PMEUS group. Electron microscopy showed endothelial damage in both the MEUS group and PMEUS group. After MWA, coagulated volumes (V) in the PMEUS group were larger than in the remaining 3 groups (p<0.05). The cell ultrastructure disorder wasmore severe in the PMEUS group than in remaining 3 groups. Conclusion: PMEUS promotes endothelial injury and produces more obvious thrombotic occlusion, improving the therapeutic effect of MWA on the rabbit liver.
Ultrasonography as an educational tool for students – any progress?
Authors: Dudea Sorin M.
Published: December 2016

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Non-mass lesions on screening breast ultrasound
Authors: Lee Jihyun , Lee Jin Hwa , Baik Seonmi , Cho Eun , Kim Dong Won , Kwon Hee Jin , Kim Eun Kyung
Published: December 2016

Aim: The purpose of this study was to determine the significance of a non-mass lesion (NML) which is recognized during screening breast ultrasound (US). Materials and methods: We included patients with a NML on screening breast US and no suspicious finding on mammography between March 2008 and June 2012. The final diagnoses were based on pathology results and a clinical or sonographic follow-up for more than 12 months. We calculated the incidence, likelihood of malignancy, and positive predictive value (PPV) of biopsy with a review of imaging and histopathological findings. Results: A total of 17868 screening breast US were performed in 8856 asymptomatic patients. Ninety-five NMLs were detected in 88 patients (1.0%). Among the 93 lesions that were followed or confirmed histopathologically, 2 (2.2%) were malignant, 89 (95.6%) were benign, and 2 (2.2%) were high risk lesions. The likelihood of malignancy in a NML on screening breast US was 2.2% and the PPV of biopsy was 6.3% (2 of 32). Conclusion: The likelihood of malignancy for a NML on screening breast US was greater than 2%. It could be classified as a BI-RADS category 4a lesion and tissue diagnosis is warranted. This provides the potential management guidelines for a NML in screening patients and further prospective studies in a large, multicenter screening population are required.
A dilemma at gray scale thyroid ultrasound: microcalcification or not? Differentiation with Acoustic Radiation Force Impulse Imaging–Virtual Touch Imaging.
Authors: Yildirim Duzgun , Samanci Cesur , Ustabasioglu Fethi Emre , Alis Deniz , Colakoglu Bulent , Bakır Alev , Tutar Onur , Klavuz Ahmet Erdem , Kaur Ahmet
Published: December 2016

Aims: To evaluate the capacity of virtual touch imaging (VTI) of the acoustic radiation force impulse (ARFI) techniquein the differential diagnosis of micro-echogenicities in thyroid nodules. Material and methods: The study comprised 28patients. Gray scale and ARFI displacement maps were used during ultrasound examination.In the same session, fine needleaspiration biopsy (FNAB) samples were obtained from the dominant nodule hav-ing micro-echogenicities. Two radiologists blinded to the FNAB results and clinical data of the patients evaluated these images and rated ARFI echogenicities according to the degree of shining points on the displacement maps and classified them as isohypoechogenic, isohyperechogenic, and obvious hyperechogenic. To differentiate between benignancy and malignancy, “a new sign” was defined as follows: in the ARFI maps obtained by VTI, iso-echogenic or hyper-echogenic appearance of micro-echogenic foci was evaluated as benignancy and hypo-echogenic appearance of micro-echogenic foci was evaluated as malignancy. Results: The FNAB results indicated 14 cases and benign nodules in the other 14 cases. Interobserver agreement between the two radiologists was highly significant for the classification of the micro-echogenic foci (Kappa=0.659, p<0.001). When we reclassified the hyperechoic and isohyperechoic foci as “benign” and isohypoechoic foci as “malignant”, the interobserver agreement between the two radiologists increased (Kappa=0.772, p<0.001). The evaluation of the first and second radiologists were highly concordant with the gold standard pathology results (Kappa=0.786, p<0.001 and Kappa=0.714, p<0.001, respectively). Conclusions: ARFI method with specific VTI features could be a very useful tool in the differentiation of malignant microcalcifications in thyroid nodules.
Intra-articular hyaluronic acid vs platelet-rich plasma in the treatment of hip osteoarthritis.
Authors: Sante Luca Di , Villani Ciro , Santilli Valter , Valeo Massimo , Bologna Emmalisa , Imparato Luca , Paoloni Marco , Iagnocco Annamaria
Published: December 2016

viscosupplementation (hyaluronic acid [HA]) in hip osteoarthritis. Material and methods: A total of 43 patients affected by monolateral severe hip osteoarthritis (OA) were included in the study. Patients were randomized to receive either intra-articular PRP (3 ml) or HA (30 mg/2 ml; 1,000-2,900 kDa), 3 injections in total – 1/week. Clinical assessments for each patient were made at baseline (T0), 4 (T1), and 16 weeks (T2) of follow-up. The primary efficacy outcome was pain reduction as measured by VAS and by WOMAC pain subscale. Results: Data analysis revealed that, compared to T0, in the PRP-treated group VAS scores significantly decreased at T1 but not at T2, thereby indicating an early effect on pain which was not maintained at a longer term follow-up. In the HA group a significant decrease of both VAS and WOMAC values was registered only between T0 and T2. Conclusions: Intra-articular PRP had an immediate effect on pain that was not maintained at longer term follow-up when, on the contrary, the effects of intra-articular HA were evident.
Strain Elastography (SE) for liver fibrosis estimation – which elastic score to calculate?
Authors: Gersak Mariana M. , Lupșor-Platon Monica , Badea Radu , Ciurea Anca , Dudea Sorin M
Published: December 2016

Liver fibrosis scoring by liver biopsy has become a rarity in daily practice mainly because many non-invasive methods with similar accuracy have been developed. Among all ultrasound elastography imaging methods, Strain Elastography (SE) is the most widely available. Although SE is a qualitative and semi-quantitative method, there is reliable applicability for liver fibrosis estimation and multiple ways to transform SE into a quantitative method, in order to obtain a fibrosis score. The aim of this review is to briefly introduce all these methods and to offer support in choosing the best estimation method for liver fibrosis, with SE.
Lung artefacts and their use
Authors: Dietrich Christoph F , Mathis Gebhard , Blaivas Michael , Volpicelli Giovanni , Seibel Armin , Atkinson Nathan S , Cui Xin Wu , Mei Fan , Schreiber-Dietrich Dagmar , Yi Dong
Published: December 2016

The science of lung ultrasound has grown tremendously over the last two decades and lung ultrasound has not only entered the mainstream of point of care ultrasound but has become a dominant topic. Understanding lung ultrasound signs and artifacts is critical to being able to correlate findings with actual pathology and normal anatomy and physiology. Investigators have described multiple lung ultrasound artifacts and findings and it is important to understand both the physics and anatomic basis behind them. Additionally, ultrasound machine use and transducer selection can significantly affect results obtained on patient during an examination and the provider must carefully choose the correct settings. This manuscript describes the state of the art in ultrasound artifact recognition and correlation as well as management of ultrasound technology to optimize diagnostic success.
Is strain elastography beneficial for isoechoic cholangiocarcinomas?
Authors: Burulday Veysel , Koc Ural , Tan Sinan
Published: December 2016

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Detection of arterioportal shunt on long term follow-up of a patient diagnosed with liver abscess
Authors: Sandulescu Larisa , Cazacu Sergiu Marian , Vintila Madalina , Firulescu Sineta , Lucan Laura , Sandulescu Sarmis Marian , Dinescu Stefan Cristian
Published: December 2016

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Solving transient acoustic boundary value problems with equivalent sources using a lumped parameter approach
Authors: Fahnline John B.
Published: December 2016

An equivalent source method is developed for solving transient acoustic boundary value problems. The method assumes the boundary surface is discretized in terms of triangular or quadrilateral elements and that the solution is represented using the acoustic fields of discrete sources placed at the element centers. Also, the boundary condition is assumed to be specified for the normal component of the surface velocity as a function of time, and the source amplitudes are determined to match the known elemental volume velocity vector at a series of discrete time steps. Equations are given for marching-on-in-time schemes to solve for the source amplitudes at each time step for simple, dipole, and tripole source formulations. Several example problems are solved to illustrate the results and to validate the formulations, including problems with closed boundary surfaces where long-time numerical instabilities typically occur. A simple relationship between the simple and dipole source amplitudes in the tripole source formulation is derived so that the source radiates primarily in the direction of the outward surface normal. The tripole source formulation is shown to eliminate interior acoustic resonances and long-time numerical instabilities.
Infant-directed speech reduces English-learning infants' preference for trochaic words
Authors: Wang Yuanyuan , Lee Christopher S. , Houston Derek M.
Published: December 2016

Over the past couple of decades, research has established that (1) infant-directed speech (IDS) facilitates speech, language, and cognitive development; and (2) infants are sensitive to the rhythmic structures in the ambient language. However, little is known about the role of IDS in infants' processing of rhythmic structures. Building on these two lines of research, whether IDS enhances infants' sensitivity to the predominant stress pattern (trochaic) in English was asked. To address this question, 9-month-old American infants were familiarized and tested with both trochaic (e.g., lazy) and iambic (e.g., cartoon) words presented in either IDS or adult-directed speech (ADS). Infants showed listening preference for the trochaic over iambic words when the speech was presented in ADS, but not in IDS. These results suggest that IDS attenuates infants' preference for trochaic stress pattern. Further acoustical analyses demonstrated that IDS provided less salient spectral cues for the contrasts between stressed and unstressed syllables in trochaic words. These findings encourage further efforts to explore the effects of IDS on language acquisition from a broader perspective.
Perceptually salient spectrotemporal modulations for recognition of sustained musical instruments
Authors: Thoret Etienne , Depalle Philippe , McAdams Stephen
Published: December 2016

Modulation Power Spectra include dimensions of spectral and temporal modulation that contribute significantly to the perception of musical instrument timbres. Nevertheless, it remains unknown whether each instrument's identity is characterized by specific regions in this representation. A recognition task was applied to tuba, trombone, cello, saxophone, and clarinet sounds resynthesized with filtered spectrotemporal modulations. The most relevant parts of this representation for instrument identification were determined for each instrument. In addition, instruments that were confused with each other led to non-overlapping spectrotemporal modulation regions, suggesting that musical instrument timbres are characterized by specific spectrotemporal modulations.
Does Short-Duration Heat Exposure at a Matched Cardiovascular Intensity Improve Intermittent-Running Performance in a Cool Environment?
Authors: Philp Calvin P. , Buchheit Martin , Kitic Cecilia M. , Minson Christopher T. , Fell James W.
Published: December 2016

Purpose:

To investigate whether a 5-d cycling training block in the heat (35°C) in Australian Rules footballers was superior to exercising at the same relative intensity in cool conditions (15°C) for improving intermittent-running performance in a cool environment (<18°C).

Methods:

Using a parallel-group design, 12 semiprofessional football players performed 5 d of cycling exercise (70% heart-rate reserve [HRR] for 45 min [5 × 50-min sessions in total]) in a hot (HEAT, 35°C ± 1°C, 56% ± 9% RH) or cool environment (COOL, 15°C ± 3°C, 81% ± 10% RH). A 30-15 Intermittent Fitness Test to assess intermittent running performance (VIFT) was conducted in a cool environment (17°C ± 2°C, 58 ± 5% RH) before and twice after (1 and 3 d) the intervention.

Results:

There was a likely small increase in VIFT in each group (HEAT, 0.5 ± 0.3 km/h, 1.5 ± 0.8 × smallest worthwhile change [SWC]; COOL, 0.4 ± 0.4 km/h, 1.6 ± 1.2 × SWC) 3 d postintervention, with no difference in change between the groups (0.5% ± 1.9%, 0.4 ± 1.4 × SWC). Cycle power output during the intervention was almost certainly lower in the HEAT group (HEAT 1.8 ± 0.2 W/kg vs COOL 2.5 ± 0.3 W/kg, –21.7 ± 3.2 × SWC, 100/0/0).

Conclusions:

When cardiovascularexercise intensity is matched (ie, 70% HRR) between environmental conditions, there is no additional performance benefit from short-duration moderate-intensity heat exposure (5 × 50 min) for semiprofessional footballers exercising in cool conditions. However, the similar positive adaptations may occur in HEAT with 30% lower mechanical load, which may be of interest for load management during intense training or rehabilitation phases.
Cold-Water Immersion and Contrast Water Therapy: No Improvement of Short-Term Recovery After Resistance Training
Authors: Argus Christos K. , Broatch James R. , Petersen Aaron C. , Polman Remco , Bishop David J. , Halson Shona
Published: December 2016

Context:

An athlete’s ability to recover quickly is important when there is limited time between training and competition. As such, recovery strategies are commonly used to expedite the recovery process.

Purpose:

To determine the effectiveness of both cold-water immersion (CWI) and contrast water therapy (CWT) compared with control on short-term recovery (<4 h) after a single full-body resistance-training session.

Methods:

Thirteen men (age 26 ± 5 y, weight 79 ± 7 kg, height 177 ± 5 cm) were assessed for perceptual (fatigue and soreness) and performance measures (maximal voluntary isometric contraction [MVC] of the knee extensors, weighted and unweighted countermovement jumps) before and immediately after the training session. Subjects then completed 1 of three 14-min recovery strategies (CWI, CWT, or passive sitting [CON]), with the perceptual and performance measures reassessed immediately, 2 h, and 4 h postrecovery.

Results:

Peak torque during MVC and jump performance were significantly decreased (P < .05) after the resistance-training session and remained depressed for at least 4 h postrecovery in all conditions. Neither CWI nor CWT had any effect on perceptual or performance measures over the 4-h recovery period.

Conclusions:

CWI and CWT did not improve short-term (<4-h) recovery after a conventional resistance-training session.
Biomechanics in Paralympics: Implications for Performance
Authors: Morriën Floor , Taylor Matthew J. D. , Hettinga Florentina J.
Published: December 2016

Purpose:

To provide an overview of biomechanical studies in Paralympic research and their relevance for performance in Paralympic sports.

Methods:

The search terms paralympic biomechanics, paralympic sport performance, paralympic athlete performance, and paralympic athlete were entered into the electronic database PubMed.

Results:

Thirty-four studies were found. Biomechanical studies in Paralympics mainly contributed to performance enhancement by technical optimization (n = 32) and/or injury prevention (n = 6). In addition, biomechanics was found to be important in understanding activity limitation caused by various impairments, which is relevant for evidence-based classification in Paralympic sports (n = 6). Distinctions were made between biomechanical studies in sitting (41%), standing (38%), and swimming athletes (21%). In sitting athletes, mostly kinematics and kinetics in wheelchair propulsion were studied, mainly in athletes with spinal-cord injuries. In addition, kinetics and/or kinematics in wheelchair basketball, seated discus throwing, stationary shot-putting, hand-cycling, sit-skiing, and ice sledge hockey received attention. In standing sports, primarily kinematics of athletes with amputations performing jump sports and running and the optimization of prosthetic devices were investigated. No studies were reported on other standing sports. In swimming, mainly kick rate and resistance training were studied.

Conclusions:

Biomechanical research is important for performance by gaining insight into technical optimization, injury prevention, and evidence-based classification in Paralympic sports. In future studies it is advised to also include physiological and biomechanical measures, allowing the assessment of the capability of the human body, as well as the resulting movement.
Activity Profiles and Positional Differences of Handball Players During the World Championships in Qatar 2015
Authors: Cardinale Marco , Whiteley Rodney , Hosny Ahmed Abdelrahman , Popovic Nebojsa
Published: December 2016

Context:

Handball is an Olympic sport played indoors by 6 court players and 1 goalkeeper with rolling substitutions. Limited data exist on elite players competing in a world championship, and virtually no information exists on the evolution of time–motion performance over the course of a long tournament.

Purpose:

To analyze time–motion characteristics of elite male handball players of the last world championships, played in Qatar in 2015.

Participants:

384 handball players from 24 national teams.

Methods:

The athletes were analyzed during 88 matches using a tracking camera system and bespoke software (Prozone Handball v. 1.2, Prozone, Leeds, UK).

Results:

The average time on court (N = 2505) during the world championships for all players was 36:48 ± 20:27 min. Goalkeepers and left and right wings were on court most of the playing time (GK 43.00 ± 25:59 min; LW 42:02 ± 21:07 min; RW 43:44 ± 21:37 min). The total distance covered during each game (2607.5 ± 1438.4 m) consisted mostly of walking and jogging. The cumulative distance covered during the tournament was 16,313 ± 9423.3 m. Players performed 857.2 ± 445.7 activity changes with a recovery time of 124.3 ± 143 s. The average running pace was 78.2 ± 10.8 m/min. There was no significant difference between high-ranked and lower-ranked teams in terms of distance covered in different locomotion categories.

Conclusions:

Specific physical conditioning is necessary to maximize performance of handball players and minimize the occurrence of fatigue when performing in long tournaments.
Quantification of Training and Competition Loads in Endurance Sports: Methods and Applications
Authors: Mujika Iñigo
Published: December 2016

Training quantification is basic to evaluate an endurance athlete’s responses to training loads, ensure adequate stress/recovery balance, and determine the relationship between training and performance. Quantifying both external and internal workload is important, because external workload does not measure the biological stress imposed by the exercise sessions. Generally used quantification methods include retrospective questionnaires, diaries, direct observation, and physiological monitoring, often based on the measurement of oxygen uptake, heart rate, and blood lactate concentration. Other methods in use in endurance sports include speed measurement and the measurement of power output, made possible by recent technological advances such as power meters in cycling and triathlon. Among subjective methods of quantification, rating of perceived exertion stands out because of its wide use. Concurrent assessments of the various quantification methods allow researchers and practitioners to evaluate stress/recovery balance, adjust individual training programs, and determine the relationships between external load, internal load, and athletes’ performance. This brief review summarizes the most relevant external- and internal-workload-quantification methods in endurance sports and provides practical examples of their implementation to adjust the training programs of elite athletes in accordance with their individualized stress/recovery balance.