bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantum Dot Temperature Sensor Ab Initio Test: Droplet Vaporization Heat Transfer
Authors: Al Hashimi Husain , Kim Jungho
Published: November 2016

Better understanding of phase change phenomena can be obtained through local measurements of the heat transfer process, which can’t be attained by traditional thermocouple point measurements. Infrared (IR) technology, which has been used by many researchers in the past, cannot be used under certain circumstances due to spectral transparency issues present in some materials. In the current study, Quantum Dots (QDs) are proposed as a novel tool for heat transfer measurements. QDs are nano-sized semiconductor materials which fluoresce upon excitation by blue or UV light. The light intensity emitted by QDs drops with temperature, which can be utilized to obtain the surface temperature distribution at a camera pixel resolution. If QDs are distributed on a surface of interest and optical access to that surface is available, the heat transfer processes can be examined using inexpensive equipment such as CCD/CMOS cameras and LED excitation sources. In this paper, a description of a QD based technique is given, where it is applied to visualize the heat transfer associated with ethanol droplet evaporation.
Mode Resolved Continuum Mechanics Model of Phonon Scattering From Embedded Cylinders
Authors: Unni Vineet , Feser Joseph P.
Published: November 2016

Phonon scattering from media with embedded spherical nanoparticles has been studied extensively over the last decade due to its application to reducing the thermal conductivity of thermoelectric materials. However, similar studies of thermal transport in fiber-embedded media have received little attention. Calculating the thermal conductivity tensor from microscopic principles requires knowledge of the scattering cross section spanning all possible incident elastic wave orientations, polarizations and wavelengths including the transition from Rayleigh to geometric scattering regimes. In this paper, we use continuum mechanics to develop an analytic treatment of elastic wave scattering for an embedded cylinder and show that a classic treatise on the subject contains important errors for oblique angles of incidence, which we correct. We also develop missing equations for the scattering cross section at oblique angles and study the sensitivity of the scattering cross section as a function of elas-todynamic contrast mechanisms. In particular, we find that for oblique angles of incidence, both elastic and density contrast are important mechanisms by which scattering can be controlled, but that their effects can offset one another, similar to the theory of reflection at flat interfaces. The solution developed captures the scattering physics for all possible incident elastic wave orientations, polarizations and wavelengths including the transition from Rayleigh to geometric scattering regimes, so long as the continuum approximation holds. The method thus enables incorporation of coherent scattering models into calculations of the thermal conductivity tensor for media with nanofibers.
Numerical Investigation on a Latent Thermal Energy Storage With Aluminum Foam
Authors: Buonomo Bernardo , Ercole Davide , Manca Oronzio , Nardini Sergio
Published: November 2016

In this paper, a numerical investigation on Latent Heat Thermal Energy Storage System (LHTESS) based on a phase change material (PCM) in a metal foam is accomplished. A vertical shell and tube LHTESS made with two concentric aluminum tubes is investigated. The internal surface of the hollow cylinder is at a constant temperature above the PCM melting temperature to simulate the heat transfer from a hot fluid. The other external surfaces are assumed adiabatic. The phase change of the PCM is modeled with the enthalpy porosity theory while the metal foam is considered as a porous media that obeys to the Darcy-Forchheimer law. Local thermal non-equilibrium (LTNE) model is assumed to analyze the metal foam and some comparison are accomplished with the local thermal equilibrium model assumption. The governing equations are solved employing the Ansys-Fluent 15 code. Numerical simulations for PCM, PCM in the porous medium in LTE and in LTNE assumptions are obtained. Results as a function of time for the charging phase are carried out for different porosities and assigned pore per inch (PPI).

The results show that at high porosity the LTE and LTNE models have the same melting time while at low porosity the LTNE has a larger melting time. Moreover, the presence of metal foam improves significantly the heat transfer in the LHTESS giving a very faster phase change process with respect to pure PCM, reducing the melting time more than one order of magnitude.
Numerical Investigation on Heat Transfer Characteristics of High Pressure Boiling Water in Vertical Internally-Ribbed Tubes
Authors: Guo Kaikai , Li Huixiong , Zhang Qing , Zhang Weiqiang , Feng Yuan
Published: November 2016

Heat transfer characteristics of high pressure boiling water flowing in vertical internally-ribbed tubes are numerically investigated with the RPI wall boiling model. Specifically, Tolubinsky’s bubble departure diameter model is applied in the present study. The numerical results indicate that the value of dref in Tolubinsky’s bubble departure diameter model needs to be modified at high pressures so that reasonable wall temperature values can be obtained. A recommended value of dref is achieved for the cases at 14.2 MPa in the present paper, and the simulated value of wall temperature is in good agreement with the corresponding experimental data collected from the published literature. Based on the present modified RPI wall boiling model, the effects of rib geometries on heat transfer characteristics of high pressure boiling water in internally-ribbed tubes are investigated. The numerical results show that the heat transfer capability of high pressure boiling water in internally-ribbed tubes increases with the increase in rib heights or the number of ribs, but decreases with the increase in helix angle of the rib. Meanwhile, the increase in rib width has little influence on the heat transfer of boiling flow in the internally-ribbed tube. The results obtained in this study will be helpful for optimizing the rib geometries of internally ribbed tubes.
Numerical Simulation for Wind Turbine Wake and Effects From Different Atmospheric Boundary Conditions
Authors: Zhou Peng , Wang Xiuling
Published: November 2016

This research focuses on the computational fluid dynamics simulation of near wind turbine wake. Three dimensional wind turbine model is built based on S809 airfoil data [1]. Three different turbulence models are used and compared. They are Realizable k-ε model, SST k-ω model, and Large Eddy Simulation (LES) model. The simulation results from different turbulence models are compared with the NREL Phase VI experiment data. Different boundary conditions, including neutral and unstable conditions, were adopted in the simulation to analyze their influence on wake flow. Updraft and downdraft are considered in this part. Overall numerical results match well with the experiment data. The discussion also compares wind turbine wake under different atmospheric boundary conditions.
Using MicroCT to Visualize Nanofluid Droplet Sorption Profiles in Unsaturated Porous Media
Authors: Munuhe Timothy , LeBrun Alexander , Zhu Liang , Ma Ronghui
Published: November 2016

Liquid droplet sorption in unsaturated porous media is an important process for a wide range of applications. However, visualizing droplet sorption is difficult due to the opaque nature of porous media used in most of the applications. In this study, microCT is used to characterize the sorption profiles of single/multiple nanofuid droplets in PMMA powder beds. The microCT scan results reveal that the region of the powder bed saturated with nanofluid has a substantially higher gray scale value than that in the unsaturated region, thus enabling the visualization of the sorption profile. It also shows that nanoparticles enhance the visualization of the sorption profiles as they tend to accumulate and stay near the wetting front even after water evaporation.
Effects of Beam Size and Pulse Duration on the Laser Drilling Process
Authors: Afrin Nazia , Ji Pengfei , Chen J. K. , Zhang Yuwen
Published: November 2016

A two-dimensional axisymmetric transient laser drilling model is used to analyze the effects of laser beam diameter and laser pulse duration on the laser drilling process. The model includes conduction and convection heat transfer, melting, solidification and vaporization, as well as material removal resulting from the vaporization and melt ejection. The validated model is applied to study the effects of laser beam size and pulse duration on the geometry of the drilled hole. It is found that the ablation effect decrease with the increasing beam diameter due to the effect of increased vaporization rate, and deeper hole is observed for the larger pulse width due to the higher thermal ablation efficiency.
Experimental Investigation of Oscillation Controlled Thermal Transport in Water-Based Nanofluids
Authors: Guven Oguz , Aktas Murat K. , Bayazitoglu Yildiz
Published: November 2016

The oscillatory flows are often in order to augment heat transfer rates in various processes. It is also well known fact that nanofluids provide significant enhancement in heat transfer at certain conditions. In this research, heat transfer in an oscillatory pipe flow of both water and water-alumina nanofluid were studied experimentally under low frequency regime flow conditions. The aim of the conducted research is parametric experimental investigation of the convective heat transfer in the oscillatory pipe flow. Firstly, the nanofluids were prepared and thermophysical properties weare measured. The experimental apparatus consist of a capillary pipe bundle connecting two reservoirs which are placed at the top and bottom side of the capillary pipe bundle. Upper reservoir contains the hot fluid while lower reservoir and capillary pipe bundle filled with cold fluid. The oscillatory flow in the pipe bundle is driven by the periodic vibrations of a surface mounted on the bottom end of the cold reservoir. The effects of the maximum displacement amplitude of the vibrations and volumetric concentration of nanoparticles on heat transfer were evaluated based on the measured temperature and acceleration data. It is found that heat transfer rate increases with increasing vibration displacement in the fluid.
Experimental and Numerical Study of Jet Impingement Boiling Heat Transfer on Hot Tube Array
Authors: Qiu Lu , Dubey Swapnil , Choo Fook Hoong , Duan Fei
Published: November 2016

A three-domain conjugation heat transfer problem, the model of a phase-change shell-and-tubes heat exchanger, was studied both experimentally and numerically. The saturated water was impinged onto an array of hot tubes that arranged in a confined cylindrical cavity, and then boiled during the travelling to the downstream. The tubes were hollow, through which the hot air was passing trough and supplied the heat to boil the water on the shell side. Therefore, the problem involved three conjugated heat transfer domains: outside-tube two-phase boiling flow, solid conduction in tubes and inside-tube single-phase convective flow. In the experiments, the heat transfer at three different water inlet velocities and nine different air inlet temperatures were tested. The measured wall temperatures and the transferred energy were found to be independent of water inlet velocity. The wall temperatures in the core area (in the vicinity of the dense tube array) were relatively uniform. However, a huge temperature gradient was measured at the peripheral region. The experimental data were used to validate the simulation that accomplished by ANSYS-Fluent V16.1. High quality hexahedral meshes were generated and the PRI boiling model was adopted to simulate the boiling flow and heat transfer. It showed that the simulation results agreed well with the experimental data. Based on the simulations, the detailed fluid field and the wall temperature distributions were analysis and discussed.
Modeling the Performance of Bi-Textured Micropillar Array as a Wicked Evaporator
Authors: Azarkish Hassan , Behzadmehr Amin , Frechette Luc G.
Published: November 2016

In the present work, the performance of bi-textured micro pillar arrays has been modeled as a wicked evaporator to provide steam flow via the thin film evaporation mechanism. Bi-textured micro pillar evaporator consists of an array with rough hydrophilic pillar bases and smooth hydrophobic tips. Water wicks between the rough hydrophilic sections of the micro pillar array to cover the surface, and vaporizes from the thin films that are formed in the vicinity of the pillar walls. The stability of the phase change mechanism is increased due to the change in direction of the capillary forces at the rough-smooth interface of micro pillars. The experimental results show that the pure evaporation mechanism occurs for a surface temperature above saturation on the bi-textured micro pillar array. The numerical analysis shows that there are optimal micro pillar dimensions for each surface temperature. The evaporation mass flow rate at the optimum dimensions is higher than the pool boiling mass flow rate on a bare surface at the same surface temperature. However, the wicked evaporator performance decreases for larger evaporator sizes.
Flow Patterns During Flow Boiling Instability in Silicon-Based Pin-Fin Microchannels
Authors: Xu Fayao , Wu Huiying , Liu Zhenyu
Published: November 2016

Flow patterns during boiling instability of deionized water across silicon-based microchannels with inner pin-fin arrays have been studied experimentally. Three types of microchannels with different pin-fin structures and a hydraulic diameter of 210 μm were used. During the unstable flow boiling, two types of instability modes of temperature and pressure oscillations occurred: long-period/large-amplitude oscillation mode and short-period/small-amplitude oscillation mode. There were increasing and decreasing stages of the temperature measurement during a period of long-period/large-amplitude oscillation mode. According to visualization observation, in the increasing stage of temperature oscillation for the in-line pin-fin microchannel, four two-phase flow patterns, including bubbly flow, vapor-slug flow, stratified flow, and stream flow, occurred sequentially with time; for the staggered pin-fin microchannels, the four two-phase flow patterns, together with single liquid-phase flow and single vapor-phase flow occurred sequentially with time. The flow pattern transitions were inverse between the increasing and decreasing stages of temperature measurement. Under the short-period/small-amplitude oscillation mode, only the stream flow occurred. With the increase of heat flux, the stream flow and the single vapor-phase flow occupied more and more time ratio during an oscillation period in the in-line and staggered pin-fin microchannels, respectively.
Analysis of the Momentum Transport Boundary Conditions at a Fluid-Porous Interface
Authors: Chen Hao , Wang Jiabing , Yang Kun
Published: November 2016

The porous composite system is consists of porous medium and free fluid layer, which has extensive industrial applications. The study method for the flow field in the porous composite system includes the microscopic, mesoscopic and macroscopic approaches. When the two-domain approach is adopted, which is one of the macroscopic methods, the momentum transport boundary conditions at the interface between porous medium and free fluid layer is essential to analyze the flow field in the system. When Darcy equation is adopted to describe the flow in porous region, the Beavers-Joseph (BJ) interface condition can be used. When Darcy-Brinkman equation is adopted to describe the flow in porous region, the stress-jump (Ochoa-Tapia & Whitaker: OTW) interface condition can be used. To utilize these interface conditions, the velocity slip coefficient used in the BJ interface condition and the stress-jump coefficient used in the OTW interface condition should be specified. In this paper, a brush configuration is approximately treated as the equivalent porous media in the composite system. A numerical simulation method is used to obtain the microscopic solution for the flow in the system based on the Navier-Stokes equation applied in whole system, and an analytical method is used to obtain the corresponding macroscopic solution based on the two-domain approach. By comparing the microscopic and macroscopic solutions, the velocity slip coefficient and the stress-jump coefficient are determined since they can be treated as adjustable parameters. The influence of different flow types, including Poiseuille flow, Couette flow, and free boundary flow, are investigated. Also the impact of free fluid layer thickness and porous structure on the velocity slip coefficient and the stress-jump coefficient are discussed. The results indicate that, the velocity slip coefficient and the stress-jump coefficient are not only the parameters which depend on the porous structure, but also depend on the thickness of free fluid layer and flow type. When the thickness of free fluid layer is lower than a certain value, the impact of free fluid layer thickness on the velocity slip coefficient and the stress-jump coefficient is much obvious. In addition, when the thickness of free fluid layer is small, these coefficients are found to be dependent on the flow type. However, when the thickness of free fluid layer is large, the stress jump coefficient is independent of the thickness of free fluid layer and the flow type. Thus the stress jump coefficient obtained for a specific case can be used to predict velocity for different flow types and different thickness of free fluid layers.
Thermal Model of a Thin Film Pulsed Pyroelectric Generator
Authors: Jankowski Nicholas R. , Smith Andrew N. , Hanrahan Brendan M.
Published: November 2016

Recent high energy density thin film material development has led to an increased interest in pyroelectric energy conversion. Using state-of-the-art lead-zirconate-titanate piezoelectric films capable of withstanding high electric fields we previously demonstrated single cycle energy conversion densities of 4.28 J/cm3. While material improvement is ongoing, an equally challenging task involves developing the thermal and thermodynamic process though which we can harness this thermal-to-electric energy conversion capability. By coupling high speed thermal transients from pulsed heating with rapid charge and discharge cycles, there is potential for achieving high energy conversion efficiency. We briefly present thermodynamic equivalent models for pyroelectric power generation based on the traditional Brayton and Ericsson cycles, where temperature-pressure states in a working fluid are replaced by temperature-field states in a solid pyroelectric material. Net electrical work is then determined by integrating the path taken along the temperature dependent polarization curves for the material. From the thermodynamic cycles we identify the necessary cyclical thermal conditions to realize net power generation, including a figure of merit, rEC, or the electrocaloric ratio, to aid in guiding generator design. Additionally, lumped transient analytical heat transfer models of the pyroelectric system with pulsed thermal input have been developed to evaluate the impact of reservoir temperatures, cycle frequency, and heating power on cycle output. These models are used to compare the two thermodynamic cycles. This comparison shows that as with traditional thermal cycles the Ericsson cycle provides the potential for higher cycle work while the Brayton cycle can produce a higher output power at higher thermal efficiency. Additionally, limitations to implementation of a high-speed Ericsson cycle were identified, primarily tied to conflicts between the available temperature margin and the requirement for isothermal electrical charging and discharging.
Effect of Dual Frequency Ultrasound on the Bubble Formation in a Capillary Tube
Authors: Fu Benwei , Zhao Nannan , Wang Guoyou , Ma Hongbin
Published: November 2016

A visual experimental was conducted to determine the effect of dual frequency ultrasound on the bubble formation and growth in a capillary quartz tube. The ultrasonic sound was applied to the heating section of a capillary tube by using electrically-controlled piezoelectric ceramics made of Pb-based lanthanum-doped zirconate titanates (PLZTs). The bubble formation and growth were recorded by a high speed camera. Experimental results show that the bubble formation and growth depend on PLZT frequency. When a dual frequency ultrasound (154 kHz and 474 kHz) was used, the nucleation sites for bubble formation were significantly increased and the bubble growth rate enhanced.
Correspondence optimization in 2D standardized carotid wall thickness map by description length minimization: A tool for increasing reproducibility of 3D ultrasound‐based measurements
Authors: Chen Yimin , Chiu Bernard
Published: November 2016

Purpose:

The previously described 2D standardized vessel‐wall‐plus‐plaque thickness (VWT) maps constructed from 3D ultrasound vessel wall measurements using an arc‐length (AL) scaling approach adjusted the geometric variability of carotid arteries and has allowed for the comparisons of VWT distributions in longitudinal and cross‐sectional studies. However, this mapping technique did not optimize point correspondence of the carotid arteries investigated. The potential misalignment may lead to errors in point‐wise VWT comparisons. In this paper, we developed and validated an algorithm based on steepest description length (DL) descent to optimize the point correspondence implied by the 2D VWT maps.

Methods:

The previously described AL approach was applied to obtain initial 2D maps for a group of carotid arteries. The 2D maps were reparameterized based on an iterative steepest DL descent approach, which consists of the following two steps. First, landmarks established by resampling the 2D maps were aligned using the Procrustes algorithm. Then, the gradient of the DL with respect to horizontal and vertical reparameterizations of each landmark on the 2D maps was computed, and the 2D maps were subsequently deformed in the direction of the steepest descent of DL. These two steps were repeated until convergence. The quality of the correspondence was evaluated in a phantom study and an in vivo study involving ten carotid arteries enrolled in a 3D ultrasound interscan variability study. The correspondence quality was evaluated in terms of the compactness and generalization ability of the statistical shape model built based on the established point correspondence in both studies. In the in vivo study, the effect of the proposed algorithm on interscan variability of VWT measurements was evaluated by comparing the percentage of landmarks with statistically significant VWT‐change before and after point correspondence optimization.

Results:

The statistical shape model constructed with optimized correspondence was more compact and had a better generalization ability than that constructed using the AL approach in both the phantom and in vivo studies. A statistical test on the group‐average VWT‐Change at each point of the 2D carotid template showed that the group‐average VWT‐change was significantly different from 0 in 18% of landmarks when the AL approach was used, and this percentage was reduced to 11% after correspondence optimization.

Conclusions:

The optimized correspondence resulted in a more compact and generalizable statistical shape model, and the algorithm was shown to reduce interscan variability of point‐wise VWT measurements obtained using the previously described arc‐length scaling parameterization approach.
Perceptual attributes for the comparison of head-related transfer functions
Authors: Simon Laurent S. R. , Zacharov Nick , Katz Brian F. G.
Published: November 2016

The benefit of using individual head-related transfer functions (HRTFs) in binaural audio is well documented with regards to improving localization precision. However, with the increased use of binaural audio in more complex scene renderings, cognitive studies, and virtual and augmented reality simulations, the perceptual impact of HRTF selection may go beyond simple localization. In this study, the authors develop a list of attributes which qualify the perceived differences between HRTFs, providing a qualitative understanding of the perceptual variance of non-individual binaural renderings. The list of attributes was designed using a Consensus Vocabulary Protocol elicitation method. Participants followed an Individual Vocabulary Protocol elicitation procedure, describing the perceived differences between binaural stimuli based on binauralized extracts of multichannel productions. This was followed by an automated lexical reduction and a series of consensus group meetings during which participants agreed on a list of relevant attributes. Finally, the proposed list of attributes was then evaluated through a listening test, leading to eight valid perceptual attributes for describing the perceptual dimensions affected by HRTF set variations.
Evolution of Game Demands From Young to Elite Players in Men’s Volleyball
Authors: de Alcaraz Antonio García , Valadés David , Palao José M.
Published: November 2016

Purpose:

To assess the evolution of the volleyball’s game demands throughout players’ development in men’s volleyball.

Methods:

A total of 150 sets and 6.671 rallies were analyzed. The sample was composed of 30 sets each by under-14, under-16, under-19, national senior, and international senior teams (1.291, 1.318, 1.310, 1.372, and 1.380 rallies for each category, respectively). Sets included in the sample were stratified and then randomly selected. The variables studied included play time, rest time, rallies played, jumps, hits, types of ball contact, types of game interruptions, performance of the game phases, and performance of the actions. Student t and Mann Whitney U tests were used to analyze specific differences between categories.

Results:

The results showed significant reductions in the play times of the rally (from 8.91 to 6.79 s) and the set (6 min 23 s to 4 min 30 s), significant increases in the rest times of the rally (19.64 to 26.53 s) and the set (13 min 44 s to 20 min 27 s), and a significant increase in the number of jumps per set (113.5 to 181.3). Significant improvements in the reception performance (1.57 to 2.45 out of 3), attack performance (2.13 to 2.67 out of 4), and side-out-phase success (48.4% to 69.6%) were found. Throughout the players’ development, data show an increase in the speed, intensity, and efficacy of the side-out phase.

Conclusions:

The findings provide reference values to guide athletes’ development and to monitor training and matches both physically and technically tactically.
Contribution of Psychosocial Factors to Physical Activity in Women of Color in the Saving Lives Staying Active (SALSA) Study
Authors: Mama Scherezade K. , McNeill Lorna H. , Soltero Erica G. , Orlando Edwards Raul , Lee Rebecca E.
Published: November 2016

Culturally appropriate, innovative strategies to increase physical activity (PA) in women of color are needed. This study examined whether participation in SALSA, an 8-week randomized, crossover pilot study to promote PA, led to improved psychosocial outcomes and whether these changes were associated with changes in PA over time. Women of color (N = 50) completed Internet-based questionnaires on PA, exercise self-efficacy, motivational readiness, stress, and social support at three time points. Women reported high socioeconomic status, decreases in exercise self-efficacy, and increases in motivational readiness for exercise and a number of stressful events (p < .05); changes in motivational readiness for exercise varied by group (p = .043). Changes in psychosocial factors were associated with increases in PA. Latin dance improved motivational readiness for PA. Future studies are needed to determine whether Latin dance improves other psychological measures and quality of life in women of color in an effort to increase PA and reduce health disparities.
Ironic and Reinvestment Effects in Baseball Pitching: How Information About an Opponent Can Influence Performance Under Pressure
Authors: Gray Rob , Orn Anders , Woodman Tim
Published: November 2016

Are pressure-induced performance errors in experts associated with novice-like skill execution (as predicted by reinvestment/conscious processing theories) or expert execution toward a result that the performer typically intends to avoid (as predicted by ironic processes theory)? The present study directly compared these predictions using a baseball pitching task with two groups of experienced pitchers. One group was shown only their target, while the other group was shown the target and an ironic (avoid) zone. Both groups demonstrated significantly fewer target hits under pressure. For the target-only group, this was accompanied by significant changes in expertise-related kinematic variables. In the ironic group, the number of pitches thrown in the ironic zone was significantly higher under pressure, and there were no significant changes in kinematics. These results suggest that information about an opponent can influence the mechanisms underlying pressure-induced performance errors.
Cross Sectional Area of the Supraspinatus Muscle and Acromio-humeral Distance in Overhead Athletes With and Without Shoulder Pain: A Cross-sectional Study
Authors: Benitez-Martinez Josep C. , Casaña-Granell Jose , de Llago Yasmin Ezzatvar , Villaron-Casales Carlos , Espi-Lopez Gemma V. , Jimenez-Diaz Fernando
Published: November 2016

Context:

The supraspinatus muscle has an important role in the stabilization of the glenohumeral joint. Identifying abnormalities concerning its size and the subacromial space in the presence of pain may be relevant to provide more specific treatments focused on the etiology of pain.

Objective:

To determinate whether painful shoulder causes changes in the supraspinatus cross-sectional area (CSA) and the acromio-humeral distance (AHD) between overhead athletes.

Design:

Cross-sectional study.

Setting:

University campus and local sports clubs’ Physical Therapist room.

Participants:

81 male overhead athletes were divided into 2 groups according to the presence of shoulder pain and clinical symptoms.

Main Outcome Measures:

Ultrasonography measurements of the supraspinatus CSA and the AHD in 2 groups of overhead athletes with and without pain.

Results:

In the pain group, the CSA was significantly smaller compared with the no pain group. No differences between groups were found in the AHD measurement.

Conclusions:

Shoulder pain in overhead athletes was associated with a reduction in their supraspinatus muscle CSA, but not in the AHD. These findings suggest that muscle atrophy exists in the presence of pain. However, in active overhead athletes, the AHD is not clearly reduced in overhead athletes with shoulder pain. Further studies are needed to understand this condition.
Examining the Experiences of Peer Mentored Athletes Competing in Elite Sport
Authors: Hoffmann Matt D. , Loughead Todd M. , Bloom Gordon A.
Published: November 2016

The general objective of the current study was to explore the experiences of elite level athletes who reported being peer mentored by other athletes during their sporting careers. The primary purpose was to identify the mentoring functions provided by athlete mentors, while the secondary purpose was to examine the outcomes related to peer mentored athletes’ (i.e., protégés) mentoring experiences. Individual interviews were conducted with 14 elite peer mentored athletes, and the data were analyzed using a hierarchical content analysis. The results indicated that athlete mentors provided a variety of specific functions that facilitated protégés’ progression through sport and development from a personal standpoint. The findings also showed that protégés benefitted in terms of enhanced performance and confidence, and also demonstrated a willingness to provide mentorship to their peers. In sum, the results of the current study may be used to enhance the effectiveness of peer mentoring relationships between athletes.
Zika virus produces noncoding RNAs using a multi-pseudoknot structure that confounds a cellular exonuclease
Authors: Akiyama Benjamin M. , Laurence Hannah M. , Massey Aaron R. , Costantino David A. , Xie Xuping , Yang Yujiao , Shi Pei-Yong , Nix Jay C. , Beckham J. David , Kieft Jeffrey S.
Published: November 2016

Zika virus uses a convoluted RNA fold to produce noncoding RNAs associated with pathogenesis.
Science of the World Wide Web
Authors: Hendler James , Hall Wendy
Published: November 2016

Web science must remain an interdisciplinary pursuit
Phenotypic Heterogeneity in
Mycobacterium tuberculosis
Authors: Dhar Neeraj , McKinney John , Manina Giulia
Published: November 2016

The interaction between the host and the pathogen is extremely complex and is affected by anatomical, physiological, and immunological diversity in the microenvironments, leading to phenotypic diversity of the pathogen. Phenotypic heterogeneity, defined as nongenetic variation observed in individual members of a clonal population, can have beneficial consequences especially in fluctuating stressful environmental conditions. This is all the more relevant in infections caused by
Mycobacterium tuberculosis
wherein the pathogen is able to survive and often establish a lifelong persistent infection in the host. Recent studies in tuberculosis patients and in animal models have documented the heterogeneous and diverging trajectories of individual lesions within a single host. Since the fate of the individual lesions appears to be determined by the local tissue environment rather than systemic response of the host, studying this heterogeneity is very relevant to ensure better control and complete eradication of the pathogen from individual lesions. The heterogeneous microenvironments greatly enhance
M. tuberculosis
heterogeneity influencing the growth rates, metabolic potential, stress responses, drug susceptibility, and eventual lesion resolution. Single-cell approaches such as time-lapse microscopy using microfluidic devices allow us to address cell-to-cell variations that are often lost in population-average measurements. In this review, we focus on some of the factors that could be considered as drivers of phenotypic heterogeneity in
M. tuberculosis
as well as highlight some of the techniques that are useful in addressing this issue.
Plasmonic nanostructure induced simultaneous slow and fast light propagation in a slab doped by four-level quantum dots
Authors: Solookinejad G. , Panahi M. , Sangachin E. Ahmadi , Asadpour Seyyed Hossein
Published: November 2016

The transmission and reflection properties of a pulse through a slab doped with quantum dots near a plasmonic nanostructure are investigated theoretically. It is found that by adjusting the distance between plasmonic nanostructure and dual quantum dots which is varied from 8.8 nanometer (nm) to 14.4 nanometer (nm) the transmission and reflection spectra for incident pulse through the slab can be modified. Furthermore, it is found that in the presence of plasmonic nanostructure, the reflected and transmitted pulses are completely phase dependent. Therefore, the group velocity of the reflected and transmitted pulses can be switched from slow to fast light by changing the phase difference of two laser fields.
Investigation of a broadband and polarization-insensitive optical absorber based on closed-ring resonator
Authors: Hu Dan , Wang Hong-Yan , Zhu Qiao-Fen , Zhang Xi-Wei , Tang Zhen-Jie
Published: November 2016

A broadband and polarization-insensitive optical metamaterial absorber (MA) based on the refractory metal chromium (Cr) closed-ring resonator is theoretically investigated. The semiconducting silicon dioxide (SiO[Formula: see text] thin film is introduced as the space layer in this sandwiched structure. Utilizing the symmetrical geometry of the proposed MA structure, polarization insensitivity of the broadband absorption is gained. The simulation results show that the absorber with Cr closed-ring array obtains an average absorption of 99.25% from 400[Formula: see text]nm to 900[Formula: see text]nm, covering the total visible wavelength range. This compact design may have potential applications in solar energy harvesting, thermal imaging, and emissivity control.
Compression of optical similaritons induced by cubic-quintic nonlinear media in a graded-index waveguide
Authors: Pal Ritu , Goyal Amit , Loomba Shally , Raju Thokala Soloman , Kumar C. N.
Published: November 2016

We employ the similarity reductions in two steps to obtain a family of bright and dark similaritons for the variable coefficient cubic–quintic nonlinear Schrödinger equation. Also, parameter domains are delineated in which kink and double-kink similaritons exist for this model. This methodology introduces a free parameter through cubic nonlinearity coefficient which gives us freedom to tune the amplitude and the propagation distance of similaritons in a tapered graded-index waveguide. Furthermore, we observe rapid beam compression of these similaritons for varying detuning parameter and the coefficient of cubic nonlinearity.
Knuckle Print Biometrics and Fusion Schemes -- Overview, Challenges, and Solutions
Authors: Jaswal Gaurav , Kaul Amit , Nath Ravinder
Published: November 2016

Numerous behavioral or physiological biometric traits, including iris, signature, hand geometry, speech, palm print, face, etc. have been used to discriminate individuals in a number of security applications over the last 30 years. Among these, hand-based biometric systems have come to the attention of researchers worldwide who utilize them for low- to medium-security applications such as financial transactions, access control, law enforcement, border control, computer security, time and attendance systems, dormitory meal plan access, etc. Several approaches for biometric recognition have been summarized in the literature. The survey in this article focuses on the interface between various hand modalities, summary of inner- and dorsal-knuckle print recognition, and fusion techniques. First, an overview of various feature extraction and classification approaches for knuckle print, a new entrant in the hand biometrics family with a higher user acceptance and invariance to emotions, is presented. Next, knuckle print fusion schemes with possible integration scenarios, and traditional capturing devices have been discussed. The economic relevance of various biometric traits, including knuckle print for commercial and forensic applications is debated. Finally, conclusions related to the scope of knuckle print as a biometric trait are drawn and some recommendations for the development of hand-based multimodal biometrics have been presented.
Model-based teeth reconstruction
Authors: Wu Chenglei , Bradley Derek , Garrido Pablo , Zollhöfer Michael , Theobalt Christian , Gross Markus , Beeler Thabo
Published: November 2016

In recent years, sophisticated image-based reconstruction methods for the human face have been developed. These methods capture highly detailed static and dynamic geometry of the whole face, or specific models of face regions, such as hair, eyes or eye lids. Unfortunately, image-based methods to capture the mouth cavity in general, and the teeth in particular, have received very little attention. The accurate rendering of teeth, however, is crucial for the realistic display of facial expressions, and currently high quality face animations resort to tooth row models created by tedious manual work. In dentistry, special intra-oral scanners for teeth were developed, but they are invasive, expensive, cumbersome to use, and not readily available. In this paper, we therefore present the first approach for non-invasive reconstruction of an entire person-specific tooth row from just a sparse set of photographs of the mouth region. The basis of our approach is a new parametric tooth row prior learned from high quality dental scans. A new model-based reconstruction approach fits teeth to the photographs such that visible teeth are accurately matched and occluded teeth plausibly synthesized. Our approach seamlessly integrates into photogrammetric multi-camera reconstruction setups for entire faces, but also enables high quality teeth modeling from normal uncalibrated photographs and even short videos captured with a mobile phone.
Rapid, detail-preserving image downscaling
Authors: Weber Nicolas , Waechter Michael , Amend Sandra C. , Guthe Stefan , Goesele Michael
Published: November 2016

Image downscaling is arguably the most frequently used image processing tool. We present an algorithm based on convolutional filters where input pixels contribute more to the output image the more their color deviates from their local neighborhood, which preserves visually important details. In a user study we verify that users prefer our results over related work. Our efficient GPU implementation works in real-time when downscaling images from 24 M to 70 k pixels. Further, we demonstrate empirically that our method can be successfully applied to videos.
Regional foremost matching for internet scene images
Authors: Shen Xiaoyong , Tao Xin , Zhou Chao , Gao Hongyun , Jia Jiaya
Published: November 2016

We analyze the dense matching problem for Internet scene images based on the fact that commonly only part of images can be matched due to the variation of view angle, motion, objects, etc. We thus propose
regional foremost matching
to reject outlier matching points while still producing dense high-quality correspondence in the remaining foremost regions. Our system initializes sparse correspondence, propagates matching with model fitting and optimization, and detects foremost regions robustly. We apply our method to several applications, including time-lapse sequence generation, Internet photo composition, automatic image morphing, and automatic rephotography.
Shape2Vec
Authors: Tasse Flora Ponjou , Dodgson Neil
Published: November 2016

Convolutional neural networks have been successfully used to compute shape descriptors, or jointly embed shapes and sketches in a common vector space. We propose a novel approach that leverages both labeled 3D shapes and semantic information contained in the labels, to generate semantically-meaningful shape descriptors. A neural network is trained to generate shape descriptors that lie close to a vector representation of the shape class, given a vector space of words. This method is easily extendable to range scans, hand-drawn sketches and images. This makes cross-modal retrieval possible, without a need to design different methods depending on the query type. We show that sketch-based shape retrieval using semantic-based descriptors outperforms the state-of-the-art by large margins, and mesh-based retrieval generates results of higher relevance to the query, than current deep shape descriptors.
Unsupervised texture transfer from images to model collections
Authors: Wang Tuanfeng Y. , Su Hao , Huang Qixing , Huang Jingwei , Guibas Leonidas , Mitra Niloy J.
Published: November 2016

Large 3D model repositories of common objects are now ubiquitous and are increasingly being used in computer graphics and computer vision for both analysis and synthesis tasks. However, images of objects in the real world have a richness of appearance that these repositories do not capture, largely because most existing 3D models are untextured. In this work we develop an automated pipeline capable of transporting texture information from images of real objects to 3D models of similar objects. This is a challenging problem, as an object's texture as seen in a photograph is distorted by many factors, including pose, geometry, and illumination. These geometric and photometric distortions must be undone in order to transfer the pure underlying texture to a new object --- the 3D model. Instead of using problematic dense correspondences, we factorize the problem into the reconstruction of a set of base textures (materials) and an illumination model for the object in the image. By exploiting the geometry of the similar 3D model, we reconstruct certain reliable texture regions and correct for the illumination, from which a full texture map can be recovered and applied to the model. Our method allows for large-scale unsupervised production of richly textured 3D models directly from image data, providing high quality virtual objects for 3D scene design or photo editing applications, as well as a wealth of data for training machine learning algorithms for various inference tasks in graphics and vision.
Interactive mechanism modeling from multi-view images
Authors: Xu Mingliang , Li Mingyuan , Xu Weiwei , Deng Zhigang , Yang Yin , Zhou Kun
Published: November 2016

In this paper, we present an interactive system for mechanism modeling from multi-view images. Its key feature is that the generated 3D mechanism models contain not only geometric shapes but also internal motion structures: they can be directly animated through kinematic simulation. Our system consists of two steps: interactive 3D modeling and stochastic motion parameter estimation. At the 3D modeling step, our system is designed to integrate the sparse 3D points reconstructed from multi-view images and a sketching interface to achieve accurate 3D modeling of a mechanism. To recover the motion parameters, we record a video clip of the mechanism motion and adopt stochastic optimization to recover its motion parameters by edge matching. Experimental results show that our system can achieve the 3D modeling of a range of mechanisms from simple mechanical toys to complex mechanism objects.
Benchmarking weak memory models
Authors: Ritson Carl G. , Owens Scott
Published: November 2016

To achieve good multi-core performance, modern microprocessors have weak memory models, rather than enforce sequential consistency. This gives the programmer a wide scope for choosing exactly how to implement various aspects of inter-thread communication through the system's shared memory. However, these choices come with both semantic and performance consequences, often in tension with each other. In this paper, we focus on the performance side, and define techniques for evaluating the impact of various choices in using weak memory models, such as where to put fences, and which fences to use. We make no attempt to judge certain strategies as best or most efficient, and instead provide the techniques that will allow the programmer to understand the performance implications when identifying and resolving any semantic/performance trade-offs. In particular, our technique supports the reasoned selection of macrobenchmarks to use in investigating trade-offs in using weak memory models. We demonstrate our technique on both synthetic benchmarks and real-world applications for the Linux Kernel and OpenJDK Hotspot Virtual Machine on the ARMv8 and POWERv7 architectures.
Efficient distributed workstealing via matchmaking
Authors: Parikh Hrushit , Deodhar Vinit , Gavrilovska Ada , Pande Santosh
Published: November 2016

Many classes of high-performance applications and combinatorial problems exhibit large degree of runtime load variability. One approach to achieving balanced resource use is to over decompose the problem on fine-grained tasks that are then dynamically balanced using approaches such as workstealing. Existing work stealing techniques for such irregular applications, running on large clusters, exhibit high overheads due to potential untimely interruption of busy nodes, excessive communication messages and delays experienced by idle nodes in finding work due to repeated failed steals. We contend that the fundamental problem of distributed work-stealing is of rapidly bringing together work producers and consumers. In response, we develop an algorithm that performs timely, lightweight and highly efficient
matchmaking
between work producers and consumers which results in accurate load balance. Experimental evaluations show that our scheduler is able to outperform other distributed work stealing schedulers, and to achieve scale beyond what is possible with current approaches.