bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Simple Criterion to Estimate Performance of Pulse Jet Mixed Vessels
Authors: Pease Leonard F. , Bamberger Judith Ann , Mahoney Lenna A. , Yokuda S. Thomas , Minette Michael J. 
Published: December 2016

Pulse jet mixed process vessels comprise a key element of the U.S. Department of Energy’s strategy to process millions of gallons of legacy nuclear waste slurries. Slurry suctioned into a pulse jet mixer (PJM) tube at the end of one pulse is pneumatically driven from the PJM toward the bottom of the vessel at the beginning of the next pulse, forming a jet. The jet front traverses the distance from nozzle outlet to the bottom of the vessel and spreads out radially. Varying numbers of PJMs are typically arranged in a ring configuration within the vessel at a selected radius and operated concurrently. Centrally directed radial flows from neighboring jets collide to create a central upwell that elevates the solids in the center of the vessel when the PJM tubes expel their contents.
An essential goal of PJM operation is to elevate solids to the liquid surface to minimize stratification. Solids stratification may adversely affect throughput of the waste processing plant. Unacceptably high slurry densities at the base of the vessel may plug the pipeline through which the slurry exits the vessel. Additionally, chemical reactions required for processing may not achieve complete conversion. To avoid these conditions, a means of predicting the elevation to which the solids rise in the central upwell that can be used during vessel design remains essential.
In this paper we present a simple criterion to evaluate the extent of solids elevation achieved by a turbulent upwell jet. The criterion asserts that at any location in the central upwell the local velocity must be in excess of a cutoff velocity to remain turbulent. We find that local velocities in excess of 0.6 m/s are necessary for turbulent jet flow through both Newtonian and yield stress slurries. By coupling this criterion with the free jet velocity equation relating the local velocity to elevation in the central upwell, we estimate the elevation at which turbulence fails, and consequently the elevation at which the upwell fails to further lift the slurry. Comparing this elevation to the vessel fill level predicts whether the jet flow will achieve the full vertical extent of the vessel at the center.
This simple local-velocity criterion determines a minimum PJM nozzle velocity at which the full vertical extent of the central upwell in PJM vessels will be turbulent. The criterion determines a minimum because flow in regions peripheral to the central upwelling jet may not be turbulent, even when the center of the vessel in the upwell is turbulent, if the jet pulse duration is too short. The local-velocity criterion ensures only that there is sufficient wherewithal for the turbulent jet flow to drive solids to the surface in the center of the vessel in the central upwell.
Effect of Kinematic Viscosity of Barrier Fluids on the Performance of a Bi-Directional Integrated Pumping Ring for Dual Mechanical Seals
Authors: Warda H. A. , Adam I. G. , Rashad A. B. , Gamal Aldin M. W. 
Published: December 2016

An experimental investigation is carried out to evaluate the performance of bi-directional pumping ring for dual mechanical seals. An experimental setup is constructed, and appropriate instrumentation are employed to measure the pressure, temperature, and flow rate of the barrier fluid. The experimental study focused on the influence of the kinematic viscosity of the barrier fluid on the performance of the pumping ring. This is done by monitoring Q-ΔP curves for various barrier fluids and temperature ranges. The tests are conducted for industrial barrier fluid compositions which are recommended by vendors of dual mechanical seals, such as Propylene Glycol-water mixtures and Diesel fuel (Grade D2).
Despite the importance of the measured performance curves for process control purposes, indicated experimental curved are generalized so that they can be employed in prediction of pumping ring performance for different sizes and operational conditions. Moreover, they can be utilized for numerical models validation.
Accelerating the High-Fidelity Simulation of Turbulence: Ensemble Averaging
Authors: Makarashvili Vakhtang , Merzari Elia , Obabko Aleksandr , Fischer Paul , Siegel Andrew 
Published: December 2016

Computational fluid dynamics (CFD) is increasingly used to simulate complex industrial systems. Most CFD analysis relies on the Reynolds-averaged Navier-Stokes (RANS) approach and traditional two-equation turbulence models. Higher-fidelity approaches to the simulation of turbulence such as wall-resolved large eddy simulation (LES) and direct numerical simulation (DNS) remain limited to smaller applications or to large supercomputing platforms. Nonetheless, continued advances in supercomputing are enabling the simulation of physical systems of increasing size and complexity. These simulations can be used to gain unprecedented insight into the physics of turbulence in complex flows and will become more widespread as petascale architectures become more accessible.
As the scale and size of LES and DNS simulations increase, however, the limitations of current algorithms become apparent. For larger systems, more temporal and spatial scale must be resolved, thus increasing the time-scale separation. While the smaller time scales dictate the size and the computational cost associated with each time step, the larger time scales dictate the length of the transient. An increased time-scale separation leads to smaller time steps and longer transients, eventually leading to simulations that are impractical or infeasible. In practice the presence of multiple and strongly separated time scales limits the effectiveness of CFD algorithms for LES and DNS applied to large industrial systems. Moreover, the situation is likely to become worse as even larger systems are simulated, thus increasing the size and length of transients. At the same time transients currently simulated on petascale architectures are unlikely to become any faster on exascale architectures.
This paper presents an ensemble-averaging technique for transient simulations, aimed at collecting averaged turbulent statistics faster. The focus is on ergodic flows and simulations. Ensemble averaging involves creating multiple models and combining them to produce a desired output. This technique is commonplace in machine learning and artificial neural networks, and it is at the basis of RANS/URANS turbulence modeling. In the proposed approach, multiple instances of the same ergodic flows are simulated in parallel for a short time and summed to create an ensemble. Provided each instance is sufficiently statistically decorrelated, this allows considerable reduction in the time to solution.
This paper focuses on the theory and implementation of the methodology in Nek5000, a massively parallel open-source spectral-element code. Also presented is the application of the method to the DNS and LES simulation of channel flow and pipe flow.
Further Developments in Numerical Simulations of Wind Turbine Flows Using the Actuator Line Method
Authors: O’Dea Murphy Leo , Guessous Laila 
Published: December 2016

Current large-scale wind turbine installations are sited using layouts based on site topology, real estate costs and restrictions, and turbine power output. Existing optimization programs attempt to site multiple turbines based on simple geometric turbine wake models, which typically overestimate individual turbine output. In addition, advanced Computational Fluid Dynamics (CFD) modeling of individual turbine wake fields have revealed complex flow patterns and “wake meandering” which have not been taken into account in current optimization and flow field models. CFD models of entire turbine fields have had limited application because of the enormous compute resources required; limitations of the simplified turbine models used which do not provide high resolution results in the wake field; and the lack of efforts to adapt the results of complex CFD output to analytical models which can be incorporated into wind turbine siting optimization routines.
In this paper, we report on our efforts to simulate flow past wind turbines using a new adaptation of the Actuator Line (AL) method for turbine blade modeling. This method creates a geometric representation of each rotating turbine blade. Grid points in the CFD flow field are selected within the outline of the blades and near downstream planes, and the aerodynamic forces are calculated using traditional blade element equations. The forces are distributed using an automated routine which dynamically determines the application area based on the number of applied grid points at each time step. Turbine blades are rotated in time with progressing CFD field calculations. This method distributes blade forces without using a geometric distribution function used in other recent research. Blade forces are then input as body forces into the Navier Stokes equations in the host CFD program. A Smagorisnky LES turbulence model is employed to model turbulent effects.
To improve accuracy and reduce computing power requirements, the advanced parallel CFD code, NEK5000, is used in this study. FORTRAN subroutines are written to generate the actuator line and blade geometry, and to calculate the blade lift and drag forces. These subroutines are then linked to the solver source code and compiled.
Details of the actuator line setup and calculations, LES turbulence model, CFD flow simulation setup, and results from current turbine runs will be presented. Current results are consistent with published research. A roadmap to ongoing development will also be discussed.
Utility of transthoracic echocardiography (TTE) in assessing fluid responsiveness in critically ill patients – a challenge for the bedside sonographer.
Authors: Mielnicki Wojciech , Dyla Agnieszka , Zawada Tomasz 
Published: December 2016

Transthoracic echocardiography (TTE) has become one of the most important diagnostic tools in the treatment of critically ill patients. It allows clinicians to recognise potentially reversible life-threatening situations and is also very effective in the monitoring of the fluid status of patients, slowly substituting invasive methods in the intensive care unit. Hemodynamic assessment is based on a few static and dynamic parameters. Dynamic parameters change during the respiratory cycle in mechanical ventilation and the level of this change directly corresponds to fluid responsiveness. Most of the parameters cannot be used in spontaneously breathing patients. For these patients the most important test is passive leg raising, which is a good substitute for fluid bolus. Although TTE is very useful in the critical care setting, we should not forget the important limitations, not only technical ones but also caused by the critical illness itself. Unfortunately, this method does not allow continuous monitoring and every change in the patient’s condition requires repeated examination.Keywords: hypovolaemia; non-invasive monitoring; intensive care unit; transthoracic echocardiography
Schwannoma of the median nerve mimicking carpal tunnel syndrome in a pregnant patient. Case report.
Authors: Giasna Giokits-Kakavouli , Micu Mihaela C. , Micu Romeo 
Published: December 2016

In patients with symptoms of a peripheral neuropathy especially during pregnancy, use of imaging techniques such as Ultrasound (US) and Magnetic Resonance Imaging (MRI) may be essential for the diagnostic accomplishment. A 30-weekspregnant diabetic female attending US evaluation due to intermittent hand pain, numbness, and weakness bilaterally. Although, the US evaluation revealed the median nerve (MN) normal size, echogenicity and echo-texture within the right carpal tunnel; the US assessment applied proximally to the carpal tunnel, revealed a hypoechoic tumor-like mass and increased MN cross section area. In transverse view, the MN was detected as an eccentric, hypoechoic structure compressed by the aforementioned mass. A presence of MN schwannoma or neurofibroma was suspected. US has been proved to be extremely useful to determine location, extent as well as the type of nerve lesion.
Comparison of Critical Power and W′ Derived From 2 or 3 Maximal Tests
Authors: Simpson Len Parker , Kordi Mehdi 
Published: December 2016

Purpose:Typically, accessing the asymptote (critical power; CP) and curvature constant (W′) parameters of the hyperbolic power–duration relationship requires multiple constant-power exhaustive-exercise trials spread over several visits. However, more recently single-visit protocols and personal power meters have been used. This study investigated the practicality of using a 2-trial, single-visit protocol in providing reliable CP and W′ estimates.Methods:Eight trained cyclists underwent 3- and 12-min maximal-exercise trials in a single session to derive (2-trial) CP and W′ estimates. On a separate occasion a 5-min trial was performed, providing a 3rd trial to calculate (3-trial) CP and W′.Results:There were no differences in CP (283 ± 66 vs 282 ± 65 W) or W′ (18.72 ± 6.21 vs 18.27 ± 6.29 kJ) obtained from either the 2-trial or 3-trial method, respectively. After 2 familiarization sessions (completing a 3- and a 12-min trial on both occasions), both CP and W′ remained reliable over additional separate measurements.Conclusions:The current study demonstrates that after 2 familiarization sessions, reliable CP and W′ parameters can be obtained from trained cyclists using only 2 maximal-exercise trials. These results offer practitioners a practical, time-efficient solution for incorporating power–duration testing into applied athlete support.
Gait Asymmetry During 400- to 1000-m High-Intensity Track Running in Relation to Injury History
Authors: Gilgen-Ammann Rahel , Taube Wolfgang , Wyss Thomas 
Published: December 2016

Purpose:To quantify gait asymmetry in well-trained runners with and without previous injuries during interval training sessions incorporating different distances.Methods:Twelve well-trained runners participated in 8 high-intensity interval-training sessions on a synthetic track over a 4-wk period. The training consisted of 10 × 400, 8 × 600, 7 × 800, and 6 × 1000-m running. Using an inertial measurement unit, the ground-contact time (GCT) of every step was recorded. To determine gait asymmetry, the GCTs between the left and right foot were compared.Results:Overall, gait asymmetry was 3.3% ± 1.4%, and over the course of a training session, the gait asymmetry did not change (F1,33 = 1.673, P = .205). The gait asymmetry of the athletes with a previous history of injury was significantly greater than that of the athletes without a previous injury. However, this injury-related enlarged asymmetry was detectable only at short (400 m), but not at longer, distances (600–1000 m).Conclusion:The gait asymmetry of well-trained athletes differed, depending on their history of injury and the running distance. To detect gait asymmetries, high-intensity runs over relatively short distances are recommended.
Telomere Length in Elite Athletes
Authors: Muniesa Carlos A. , Verde Zoraida , Diaz-Ureña Germán , Santiago Catalina , Gutiérrez Fernando , Díaz Enrique , Gómez-Gallego Félix , Pareja-Galeano Helios , Soares-Miranda Luisa , Lucia Alejandro 
Published: December 2016

Growing evidence suggests that regular moderate-intensity physical activity is associated with an attenuation of leukocyte telomere length (LTL) shortening. However, more controversy exists regarding higher exercise loads such as those imposed by elite-sport participation.Methods:The authors investigated LTL differences between young elite athletes (n = 61, 54% men, age [mean ± SD] 27.2 ± 4.9 y) and healthy nonsmoker, physically inactive controls (n = 64, 52% men, 28.9 ± 6.3 y) using analysis of variance (ANOVA).Results:Elite athletes had, on average, higher LTL than control subjects, 0.89 ± 0.26 vs 0.78 ± 0.31, P = .013 for the group effect, with no significant sex (P = .995) or age effect (P = .114).Conclusions:The results suggest that young elite athletes have longer telomeres than their inactive peers. Further research might assess the LTL of elite athletes of varying ages compared with both age-matched active and inactive individuals.
Whole-Body Vibration Training Improves Heart Rate Variability and Body Fat Percentage in Obese Hispanic Postmenopausal Women
Authors: Severino Gregory , Sanchez-Gonzalez Marcos , Walters-Edwards Michelle , Nordvall Michael , Chernykh Oksana , Adames Jason , Wong Alexei 
Published: December 2016

The present study examined the effects of a 6-week whole-body vibration training (WBVT) regimen on heart rate variability (HRV) and body composition in obese Hispanic postmenopausal women. Participants were randomly assigned to either WBVT (n = 13) or a nonexercising control group (n = 14). HRV and body composition were measured before and after 6 weeks. There was a significant group by time interaction (P < .05) for heart rate, sympathovagal balance, and body fat percentage (BF%) such that all significantly decreased (P < .05); and R-R intervals significantly increased (P < .05) following WBVT compared to no changes after control. The changes in sympathovagal balance were correlated with changes in BF% (r = .63, P < .05). Our findings indicate that WBVT improves HRV and BF% in obese Hispanic postmenopausal women. The improvement in BF% partially explained the decrease in sympathovagal balance. Since obese and older individuals are at increased risk of developing cardiovascular diseases, they could potentially benefit from WBVT.
Influence of Habitual Physical Activity During Late Pregnancy on the Duration of Labor
Authors: Kondo Yuki , Sawa Ryuichi , Ebina Aoi , Takada Masayo , Fujii Hiromi , Okuyama Yoko , Tanikawa Yuko , Souke Kaoru , Ono Rei 
Published: December 2016

Background:Physical activity during pregnancy has numerous benefits, but the influence on the duration of labor is unclear. We investigated the influence of habitual physical activity during late pregnancy on the duration of labor, with consideration of previous delivery experience and the stage of labor.Methods:This prospective study included 103 women (48 nulliparous, 55 multiparous) in late pregnancy. Habitual physical activity was evaluated using the Baecke physical activity questionnaire (BQ). Women were divided into a high activity group (HA) and a low activity group (LA) based on their median total BQ score. Data pertaining to the duration of labor were obtained from the birth records after delivery.Results:In multiparous women, the duration of the second stage of labor was significantly shorter in the HA group than in the LA group [median (range): HA, 11 min (1–102 min); LA, 20 min (4–175 min); P < .05]. The significant difference persisted after adjusting for confounding variables (standardized β = –0.34; P = .01). In nulliparous women, there were no significant differences in duration of labor between groups.Conclusions:Higher physical activity in multiparous women during late pregnancy might positively influence the duration of the second stage of labor.
Physical Education Policies and Practices in California Private Secondary Schools
Authors: Kahan David , McKenzie Thomas L. 
Published: December 2016

Background:Physical education (PE) is mandated in most states, but few studies of PE in private schools exist.Methods:We assessed selected PE policies and practices in private secondary schools (grades 6 to 12) in California using a 15-item questionnaire related to school characteristics and their PE programs.Results:Responding schools (n = 450; response rate, 33.8%) were from 37 counties. Most were coeducational (91.3%) and had a religious affiliation (83%). Secular schools had more PE lessons, weekly PE min, and smaller class sizes. Most schools met guidelines for class size, but few met national recommendations for weekly PE minutes (13.7%), not permitting substitutions for PE (35.6%), and programs being taught entirely by PE specialists (29.3%).Conclusions:Private schools, which serve about 5 million US children and adolescents, may be falling short in providing quality PE. School stakeholders should encourage adoption and implementation of policies and practices that abide by professional guidelines and state statutes.
Multiple Evolutionary Trajectories Have Led to the Emergence of Races in Fusarium oxysporum f. sp. lycopersici
Authors: Biju V. Chellappan , Fokkens Like , Houterman Petra M. , Rep Martijn , Cornelissen Ben J. C. 
Published: December 2016

ABSTRACT

Race 1 isolates of
Fusarium oxysporum
f. sp.
lycopersici
(FOL) are characterized by the presence of
AVR1
in their genomes. The product of this gene, Avr1, triggers resistance in tomato cultivars carrying resistance gene
I
. In FOL race 2 and race 3 isolates,
AVR1
is absent, and hence they are virulent on tomato cultivars carrying
I
. In this study, we analyzed an approximately 100-kb genomic fragment containing the
AVR1
locus of FOL race 1 isolate 004 (FOL004) and compared it to the sequenced genome of FOL race 2 isolate 4287 (FOL4287). A genomic fragment of 31 kb containing
AVR1
was found to be missing in FOL4287. Further analysis suggests that race 2 evolved from race 1 by deletion of this 31-kb fragment due to a recombination event between two transposable elements bordering the fragment. A worldwide collection of 71 FOL isolates representing races 1, 2, and 3, all known vegetative compatibility groups (VCGs), and five continents was subjected to PCR analysis of the
AVR1
locus, including the two bordering transposable elements. Based on phylogenetic analysis using the EF1-α gene, five evolutionary lineages for FOL that correlate well with VCGs were identified. More importantly, we show that FOL races evolved in a stepwise manner within each VCG by the loss of function of avirulence genes in a number of alternative ways.

IMPORTANCE
Plant-pathogenic microorganisms frequently mutate to overcome disease resistance genes that have been introduced in crops. For the fungus
Fusarium oxysporum
f. sp.
lycopersici
, the causal agent of
Fusarium
wilt in tomato, we have identified the nature of the mutations that have led to the overcoming of the
I
and
I-2
resistance genes in all five known clonal lineages, which include a newly discovered lineage. Five different deletion events, at least several of which are caused by recombination between transposable elements, have led to loss of
AVR1
and overcoming of
I
. Two new events affecting
AVR2
that led to overcoming of
I-2
have been identified. We propose a reconstruction of the evolution of races in FOL, in which the same mutations in
AVR2
and
AVR3
have occurred in different lineages and the FOL pathogenicity chromosome has been transferred to new lineages several times.