bluuebunny/crossref_metadata_2025 huggingface dataset:
Recent Progress in Unsteady and Pulsatile Flow Performance Analysis of Turbocharger Turbines
Authors: Kwao-Ampomah Josiah L. , Zhuge Weiling , Zhang Yangjun
Published: December 2014

In this review, a summary and discussion of the current state of the art on computational and experimental analysis of unsteady flow effects on turbocharger turbine performance is presented. The numerical methods, for CFD analysis are first introduced and explained together with their unique advantages and limitations. Details on several approaches and test facilities used in experimental analysis of unsteady flow effects on turbine performance are compared and criticised. Conclusions of the results and discussion comprise recommendations for more accurate acquisition of data and justifications for future work needed in this field, including a twin entry volute design alteration that could reduce pulse energy loss.
Numerical and Theoretical Analysis of Laminar Counterflowing Spray Flames for Use in Turbulent Combustion Modeling
Authors: Olguin Hernan , Hindenberg Philip , Gutheil Eva
Published: December 2014

The paper presents a combined theoretical and numerical study of laminar counterflow mono-disperse spray flames. The numerical model includes a similarity transformation of the two-dimensional governing gas phase equations into a one-dimensional formulation. The reduced computational time enables the use of detailed chemical reaction mechanisms to study the spray flame structure. In particular, the effect of spray evaporation on combustion is investigated by means of numerical simulations. For this purpose, the transport equation of the scalar dissipation rate of the mixture fraction is derived, where the spray evaporation source term is included. Numerical simulations of laminar liquid and gaseous ethanol and combustion products mono disperse spray flames under fuel-rich conditions are presented and discussed. The parametric dependence of the flame structures on strain rate is studied with emphasis on the spray evaporation. Droplet reversal and oscillation are found to dominate the flame structure, and they determine the location of the main reaction zone as well as the profile of the scalar dissipation rate. The study aims to develop a novel spray flamelet model for use in the numerical simulations of turbulent spray combustion with particular emphasis on flameless conditions.
Novel Atomization Process for Large Scale Nanoparticle Production by Flame Spray Pyrolysis
Authors: Achelis Lydia , Meierhofer Florian , Hodapp Maximilian J. , Buss Lizoel , Noriler Dirceu , Meier Henry F. , Fritsching Udo
Published: December 2014

An advanced atomizer concept to obtain larger production rates of nano-particles by the Flame Spray Pyrolysis process (FSP) is investigated. In the conventional FSP process (external mixing gas/liquid nozzle) production rates may be varied by increasing the precursor feed rate and/or the precursor concentration. However, both measures typically result in the formation of larger nanoparticles. These effects may be avoided by the development and integration of advanced atomizer concepts. The aim is to address the spray structure in a way that keeps the flame height constant and modifies the flame width. Therefore, the time scales and the residence time-temperature histories of droplets and nanoparticles are expected to be similar while the production rate is increased. The atomizer concept for creation of a modified spray and flame combines a swirling liquid film generation that is atomized with an external swirling gas flow.

In the first step a hollow cone of liquid ligaments and primary droplets is generated through a conventional pressure-swirl nozzle. The liquid phase is atomized in the second step, by the expanding gas of a circular ring nozzle. To study the main characteristics of the combined atomizer in model experiments, water and water/glycerol mixtures are used as the liquid phase and air as the gas phase. For investigation of the atomizer and spray properties, the relation between liquid outlet angle, inlet angle of the gas, the gas/liquid flow rates, the spray cone geometry and droplet size distribution are investigated. The spray structure and the breakup of the film are analyzed by high speed images. Laser diffraction is used to measure the droplet size distribution in the spray.

A numerical model is developed and used to simulate the cold gas flow and spray distribution as in the adapted atomizer concept. The Eulerian-Lagranian approach is solved by means of a computational fluid dynamics (CFD) code. The process parameters such as liquid composition, liquid and gas flow rates are varied to meet the specific requirements of the nanoparticle production in the FSP process. The experimental and numerical investigation showed that an enlarged and steady spray resulted from an increased outlet angle of the liquid and gas swirl. Increased tangential velocities increase the entrainment of surrounding gas, widening and providing a more uniform velocity profile to the spray. Spray droplet mean diameters resulted in the desired range of ≤ 20 μm.
Study of Blood Flow in Micro-Channels Using Mixture Theory
Authors: Wu Wei-Tao , Aubry Nadine , Antaki James F. , Massoudi Mehrdad
Published: December 2014

It is known that in large vessels (whole) blood behaves as a Navier-Stokes (Newtonian) fluid; however, in a vessel whose characteristic dimension (e.g., a diameter in the range of 20 to 500 microns) is about the same size as the characteristic size of the blood cells, blood behaves as a non-Newtonian fluid, exhibiting complex phenomena, such as shear-thinning, stress relaxation, the Fahraeus effect, the plasma-skimming, etc.. Using the framework of mixture theory an Eulerian-Eulerian two phase model is applied to model blood flow, where the plasma is treated as Newtonian fluid and the RBCs are treated as shear thinning fluid.[5]
Oscillation of Mixing Jets in a Long Horizontal Tank
Authors: Yu Zhao , Kar Kishore , Storrs Tyrone , Jian Christopher , Cope Richard , Feng Jinli , Aglave Ravindra
Published: December 2014

In contrast to mixing in vertical tanks, jet mixing in long horizontal tanks is scarcely investigated in the literature. It is known that jet mixing in long horizontal tanks is more difficult when compared to short tanks, as more liquid volume must be recirculated through the jets.

In this study, computational fluid dynamics (CFD) simulations are conducted for the flow in a horizontal cylindrical tank with a length-to-diameter ratio of 3:1 and a nominal volume of 112,560 L (liquid volume of 75,708 L, i.e. 20,000 gallons). A pair of back-to-back Coldrey nozzles is placed near the center of the tank bottom, and each nozzle directs its jet towards the corresponding vessel end. An intriguing phenomenon is observed in the transient simulations, where the turbulent jets oscillate in both horizontal and vertical directions with a low frequency. In order to determine the source of such oscillation, a number of simulations are conducted to explore the effects of mesh type and size, boundary condition on the free surface, turbulence model, and time step. Oscillation persists in all cases, indicating that it is unlikely the result of some numerical instability. The oscillation also appears to be insensitive to the Reynolds number or symmetry in the nozzle or tank geometry. Another simulation with a single jet also shows the oscillatory flow behavior, and thus the oscillation is more likely to be caused by interaction between the jet and the recirculating flow in the tank, rather than interaction between the two jets. Further analysis of the jet velocity profile suggests that the secondary flow on the cross section of the jets might also contribute to the oscillation.

While similar confined jet oscillations due to Coanda effect and blind cavity effect have been previously observed in small cavities by both 2D numerical simulations and laboratory scale experiments, this study shows that such oscillation also exists in industrial scale horizontal tanks. The oscillatory motion of the liquid may lead to improved mixing in the tank.
Particle Image Velocimetry Measurements of Tornado-Like Flow Field in Model WindEEE Dome
Authors: Refan Maryam , Hangan Horia , Siddiqui Kamran
Published: December 2014

The flow field of tornado vortices simulated in the 1/11 scaled model of the Wind Engineering, Energy and Environment (WindEEE) Dome is characterized. Particle Image Velocimetry measurements were performed to investigate the flow dynamics for a wide range of Swirl ratios (0.12≤S≤1.29) and at various heights above the surface. It is shown that this simulator is capable of generating a wide variety of tornado like vortices ranging from a single-celled laminar vortex to a multi-celled turbulent vortex. Radial profiles of the tangential velocity demonstrated a clear variation in the experimental values with height at and after the touch-down of the breakdown bubble. Also, the comparison between experimental tangential velocities and the Rankine model estimations resulted in good agreement at only the upper levels (Z>0.35). Radial velocity values close to the surface rose as the swirl increased which is mainly due to the intensified tangential velocities in that region. In addition, variation of the radial velocity with height is more noticeable for higher swirls which can be explained by the flow regime being fully turbulent for S≥ 0.57.
Computational Analysis of Undulatory Batoid Motion for Underwater Robotic Propulsion
Authors: Sharp Nicholas , Hagen-Gates Virginia , Hemingway Evan , Syme Molly , Via Juelyan , Feaster Jeffrey , Bayandor Javid , Jung Sunghwan , Battaglia Francine , Kurdila Andrew
Published: December 2014

Underwater fish of the class Batoidea, commonly known as rays and skates, use large cartilaginous wings to propel themselves through the water. This motion is of great interest in bioinspired robotics as an alternative propulsion mechanism. Prior research has focused primarily on the oscillating kinematics used by some species which resembles flapping; this study investigates undulatory motion induced by propagating sinusoidal waves along the fin. An analytical model of undulatory kinematics is presented and correlated with biological literature, and the model is then simulated via unsteady computational fluid dynamics and multiparticle collision dynamics. A bioinspired robot, Batoid Underwater Robotics Testbed (BURT), was developed to test the kinematics of the undulating propulsion system proposed. Finally, BURT was utilized as a platform to investigate engineering challenges in undulating Batoid robotics.
Towards a Parallel Implementation of an Immersed Boundary Method on Non-Uniform Cartesian Mesh Coupled With a Fluid Structure Interaction Model
Authors: Wei Z. , Zheng Z. C.
Published: December 2014

The immersed boundary methods are well known as an efficient flow solver for engineering problems involving fluid structure interactions. However, in order to obtain better results, higher resolutions near the immersed boundary points are desired. Non-uniform Cartesian mesh can easily fulfill this task without introducing a dramatic increase on the cost of computation and coding. In the current paper, an immersed boundary method with non-uniform Cartesian mesh is demonstrated. The Poisson problem is solved with assistance of a scientific parallel computational library PETSc. The code is validated with a three-dimensional flow over a stationary sphere. Then, a fluid-structure interaction model is coupled and validated with two-dimensional vortex induced vibration problems. Comparisons with previous studies are presented. The ultimate goal is to couple the fluid-structure interaction model with the three-dimensional immersed boundary method.
Mixing Enhancement by Using Turbulent Jets
Authors: Pratomo Hariyo P. S.
Published: December 2014

Experimental results of a fully pulsed subsonic air jet issuing into the still surrounding air are reported in this paper. The intermittent flow containing a period of no flow between pulses due to the mechanically excitation was gauged by a single wire hot-wire anemometer operated in a constant temperature mode. A range of the Reynolds and Strouhal numbers of 1 × 104 < Re < 4 × 104 and 0.0064 < St < 0.0076 respectively was used to define the jets. Results of the traverse measurement agreed with earlier findings demonstrating strong effects of the excitation on the radial profiles of the mean axial velocity of the jet. Within the parameter ranges investigated, the pulsed jets were found to be significantly more spreading than steady jets. A less dispersive pulsed jet, however, appeared at a higher jet exit velocity. Strikingly, contradictory trends in the jet growth and entrainment at the higher and lower Reynolds number were seen as the lower Reynolds number does not produce a widening radial profile as a result of the increasing Strouhal number. From the axial measurements, the pulsed jets were characterized by the pulsed dominated- and high turbulence steady jet region in which their existences heavily relied on the magnitudes of the controlled parameters. A less fluctuating pulsed jet associated with the reduced magnitudes of aggregate turbulence intensity and relative turbulence energy however, appeared at an increased Strouhal number. Comparative studies with the existing results of non-circular orifice jets i.e cruciform, elliptic, and triangular jets are also reported to display the decay rates of centerline axial velocity and the spreading rates of the jets which benefit for the practical purposes.
Investigation of Pseudo Turbulent Scalar Transport in Two Phase Fluid Flow and Passive Scalar Mixing Using Simultaneous SPIV/PLIF
Authors: Ramezani Mahdi , Subramaniam Shankar , Olsen Michael G.
Published: December 2014

The presented work is focused on developing closure models for simulation of multiphase flow using multi-fluid models. In the two-fluid model, pseudo turbulent terms appear in both the heat transfer term in the energy equation and the mass transfer term in the species equation. These terms are often neglected due to lack of information, but recent studies show that they can indeed be significant in the simulation of the inter particle phenomena. In the present work, we experimentally investigate the importance of pseudo turbulent term in passive scalar transport. A simultaneous stereo particle image velocimetry and planar laser induced fluorescence (SPIV/PLIF) measurement of the field data for a liquid-solid flow is presented in this study. The results of this measurement are used to validate data from Particle Resolved DNS (PR-DNS) that in turn is used to develop the aforementioned closure models. In this work, results for a single sphere are presented for Reynolds number ranging from 50 to 150. In addition, results for arrays of spheres representing volume fractions of 0.1 and 0.2 are presented for the same range of Reynolds number.
Numerical Simulation of Interior Flow in Evaporation Droplet
Authors: Dong Qingming , Wang Zhentao , Zhang Yonghui , Wang Junfeng
Published: December 2014

In this present study, the VOF (Volume of Fluid) approach is adopted to capture the interface, and CSF (Continuum Surface Force) model to calculate the surface tension, and the governing equations are founded in numerical simulation of evaporating droplets. In this work, a water droplet is assumed to be suspending in high temperature air, and the gravity of a droplet is ignored. During evaporating process of the droplet, the internal circulation flow will be induced due to the gradient of temperature at the droplet surface. The interface flows from high temperature area to low temperature area, which pulls the liquid to produce convective flow inside the droplet called as Marangoni flow. Marangoni flow makes the temperature distribution tend to uniformity, which enhances heat transfer but weakens Marangoni flow in turn. So, during droplet evaporation, the internal flow is not steady.
Suppression of the Vortex-Induced Vibration of a Circular Cylinder With Permeable Meshes
Authors: Cicolin Murilo M. , Freire Cesar M. , Assi Gustavo R. S.
Published: December 2014

Experiments have been carried out on models of rigid circular cylinders fitted with three different types of permeable meshes to investigate their effectiveness in the suppression of vortex-induced vibrations (VIV). Measurements of the dynamic response are presented for models with low mass and damping which are free to respond in the cross-flow direction. Reynolds number ranged from 1,000 to 10,000 and reduced velocity was varied between 2 and 13. Also presented are measurements of the wake of static models with Particle Image Velocimetry (PIV) at Reynolds number equal to 4000. Results for two meshes made of ropes and cylindrical tubes are compared with the VIV response of a bare cylinder and that of a known suppressor called the “ventilated trousers” (VT). All three meshes achieved an average 50% reduction of the response when compared with that of the bare cylinder. The sparse mesh configuration presented a similar behaviour to the VT, while the dense mesh produced considerable VIV response for an indefinitely long range of reduced velocity. Visualisation of the flow by PIV around static cylinders revealed that all suppressors disrupt the vortex shedding and increase the formation length when compared to the bare cylinder. The VT mesh, which presented the best suppression, also presented the largest vortex formation length.
Numerical Investigation of Multiphase Flow Hydrodynamics in Trickle Bed Reactors
Authors: Kurnia Jundika Candra , ben Salem Imen , Nadeem Humair , Shamim Tariq , Sassi Mohamed
Published: December 2014

For decades, trickle bed reactors (TBRs) have been widely used in chemical process industries due to their cost effectiveness and simplicity in operation. Despite their wide use, designing efficient TBRs is challenging, considering the complexity of various transport processes and interactions that occur simultaneously in TBRs. Hence, it is of prime importance to have a comprehensive understanding on the multiphase flow inside TBRs. The objective of this study is to investigate hydrodynamic of multiphase flow and to identify the flow regime developed inside TBRs. Multiphase flow inside TBRs is investigated by utilizing the well-established computational fluid dynamics approach and experimental study. A “discrete particle” approach together with Volume of Fluid multiphase flow modeling is utilized in this study. The effect of the bed particle diameter, spacing, and arrangement is examined and evaluated. The results are analyzed with regards to liquid content and pressure drop. The findings will assist in developing guidelines for designing TBRs.
Assessment of Distributed Fiber Optic Sensors for Flow Field Temperature Mapping
Authors: Lomperski Steve , Gerardi Craig
Published: December 2014

Distributed fiber optic temperature sensing based on Rayleigh scattering is a relatively new technique offering data density unachievable with point sensors such as thermocouples and RTDs. Thousands of temperature measurements can be generated by a single fiber optic cable suspended within a flow field. And unlike imaging techniques such as laser induced fluorescence, fiber optic sensors are suitable for applications involving opaque fluids. But verifying measurement accuracy along a distributed temperature sensor (DTS) can be problematic. Unlike traditional sensors such as thermocouples, DTS calibration shifts can accompany sensor handling or movement because they respond to strain as well as temperature. This paper describes an assessment of a Rayleigh scattering-based sensing system used to measure air temperature within a 1 × 1 × 1.7 m tank used for thermal mixing experiments. Two 40 m-long DTSs were strung across the tank midplane at 16 levels. Stability in stagnant air was examined over seven days and found to be generally better than ± 0.5°C with local regions of drift up to 1.5°C. DTSs were also tested in isothermal flow to assess signal degradation associated with flow-induced vibration. Noise increased with flow velocity, inducing data loss that grew with distance along the fiber. Despite data losses >50% in high noise regions, mean temperatures after simple filtering agreed with low noise regions to within ∼4°C.
Numerical Investigation of the Effect of Blockage on the Hydrodynamic Coefficients of a Prolate Spheroid
Authors: Bochio Gustavo , Assi Gustavo R. S.
Published: December 2014

Experiments with submarine models in cavitation tunnels are limited by the length scale of the body in relation to the size of the test section. Especially for high angles of attack, the body will experience strong flow interference due to the proximity of the walls. Consequently, the hydrodynamic coefficients will normally require empirical corrections in order to be extrapolated to represent open-water flows. The present work investigates the effect of local hydrodynamic blockage, i.e. the ratio between the body frontal area to the cross area of the test section, on the determination of the hydrodynamic coefficients of a prolate spheroid. Numerical simulations of the flow around the body in various angles of attack were performed solving the Re-averaged Navier-Stokes equations for Reynolds numbers in the range of 60 million. The numerical domain is built to represent the test section of a large cavitation tunnel in full scale. Results for coefficients of lift, drag and pitching moment are compared for several cases with blockage ratio of 0%, 1% and 5% and angle of attack of 0 and 10 degrees. The maximum deviation of around 30% from the reference case was obtained at the angle of attack of 10 degrees for the highest blockage ratio. The topology of the flow showed no significant dependency on blockage for the tested range.
Influence of Design Parameters on the Global Performances of Low-Speed Counter-Rotating Axial-Flow Fans
Authors: Wang Juan , Ravelet Florent , Bakir Farid
Published: December 2014

The present work aims at experimentally investigating the effects of some parameters on the performances of a counter-rotating stage, and on the instationary flow between the rotors. Three counter-rotating fans, which have the same design point, have been designed. These systems differ by the distribution of the loading and of the ratio of angular velocity between the front rotor and the rear rotor. All the configurations have been tested in a normalized test rig, where the ratio of angular velocities and the axial distance between the two rotors can be varied. The influence of these parameters are then addressed by analysing the experimental results of the static pressure rise and static efficiency, as well as of the wall pressure fluctuations registered by a microphone at the wall. The three systems achieve the design point with a high efficiency. The counter-rotating systems lead to at least a 10 percentage points gain in static efficiency at the design flow rate, compared to the typical peak efficiency of a traditional rotor-stator stage. Meanwhile, counter-rotating systems display good working stabilities at very low volume flow rates. In addition, at the design speed ratio, the overall performance decreases almost monotonically with the axial distance. Nevertheless, an optimum in axial distance can be found for higher speed ratios. Finally, the investigations of the wall pressure fluctuations show that the amplitudes of power spectral density corresponding to the blade passing frequency of the rear rotor are significantly higher than that of the front rotor. The interaction peaks are also stronger for an equal distribution of the work on the two rotors.
Flow Structure and Penetration Behavior of a Submerged Annular Jet of a Bingham Fluid
Authors: Hammad Khaled J.
Published: December 2014

The flow and penetration characteristics of a submerged annular jet of a Bingham non-Newtonian fluid were investigated numerically within the steady laminar flow regime. Central and outer recirculation regions typically characterize the flow of a Newtonian annular jet. However, in the case of a Bingham jet, once a critical yield number is exceeded, flow recirculation throughout the whole flow field is eliminated and stagnant, attached-to-the-wall regions are formed. Extent of the outer recirculation region and the recirculation strength of both the outer and central regions are found to significantly diminish with the yield number. The axial penetration of a submerged annular jet decreases with the inner-to-outer annular nozzle diameter ratio and the yield numbers. Annular jets of yield stress fluids decay continuously, very rapidly, and can vanish within the initial few jet diameters. The point at which the axial momentum of the jet vanishes shifts upstream with both the yield number and the annular diameter ratio.
Assessing Physical Activity in Older Adults: Required Days of Trunk Accelerometer Measurements for Reliable Estimation
Authors: van Schooten Kimberley S. , Rispens Sietse M. , Elders Petra J.M. , Lips Paul , van Dieën Jaap H. , Pijnappels Mirjam
Published: December 2014

We investigated the reliability of physical activity monitoring based on trunk accelerometry in older adults and assessed the number of measured days required to reliably assess physical activity. Seventy-nine older adults (mean age 79.1 ± 7.9) wore an accelerometer at the lower back during two nonconsecutive weeks. The duration of locomotion, lying, sitting, standing and shuffling, movement intensity, the number of locomotion bouts and transitions to standing, and the median and maximum duration of locomotion were determined per day. Using data of week 2 as reference, intraclass correlations and smallest detectable differences were calculated over an increasing number of consecutive days from week 1. Reliability was good to excellent when whole weeks were assessed. Our results indicate that a minimum of two days of observation are required to obtain an ICC ≥ 0.7 for most activities, except for lying and median duration of locomotion bouts, which required up to five days.
We Are Able, We Intend, We Act—But We Do Not Succeed: A Theoretical Framework for a Better Understanding of Paradoxical Performance in Sports
Authors: Lobinger Babett H. , Klämpfl Martin K. , Altenmüller Eckart
Published: December 2014

Paradoxical performance can be described simply as a sudden decrease in a top athlete’s performance despite the athlete’s having striven for superior performance, such as the lost-skill syndrome in trampolining or “the yips” in golf. There is a growing amount of research on these phenomena, which resemble movement disorders. What appears to be missing, however, is a clear phenomenology of the affected movement characteristics leading to a classification of the underlying cause. This understanding may enable specific diagnostic methods and appropriate interventions. We first review the different phenomena, providing an overview of their characteristics and their occurrence in sports and describing the affected sports and movements. We then analyze explanations for the yips, the most prominent phenomenon, and review the methodological approaches for diagnosing and treating it. Finally, we present and elaborate an action theoretical approach for diagnosing paradoxical performance and applying appropriate interventions.
Neuroleptics as a cause of painful legs and moving toes syndrome
Authors: Azzi Jacques , Atweh Samir , Saade Nayef , Jabbour Rosette
Published: December 2014

Painful legs and moving toes syndrome is rare. It is predominantly diagnosed in middle-aged adults following a history of spinal cord surgery or trauma. The syndrome consists of abnormal repetitive movements, most commonly in the lower extremities, accompanied by pain in the affected limb. Pain usually precedes the movements. We report a case in a young patient that we believe was induced by the intake of a low-potency neuroleptic, which was prescribed to him for anxiety. The patient was treated with carbamazepine with mild relief of pain and later on with botulinum injection, which significantly reduced the movements and mildly improved the pain. After stopping the treatment, the beneficial effect lasted for about 3 months after which his condition gradually returned to its initial state.
DisseminatedMycobacterium chelonaeinfection causing pacemaker lead endocarditis in an immunocompetent host
Authors: Hooda Amit , Pati Purinder K , John Bobby , George Paul V , Michael Joy Sarojini
Published: December 2014

Pacemaker infection withMycobacterium chelonaehas not been reported previously. We report the first case of pacemaker lead endocarditis due toM. chelonae, which was successfully treated with multidrug regimen.M. chelonaeis regarded as an environmental bacterium and its pathogenicity has been recognised recently. The present case illustrates its ability as a primary invader should not be underestimated, especially in an immunocompetent patient with indwelling devices. Epidemiology and management of this rare cause of culture-negative endocarditis is discussed.
Localised bullous eruptions and epidermal detachment from the extravasation of hydroxyethyl starch (Voluven)
Authors: London James , Tay Stan , Brown Brigid , Tancharoen Chasari
Published: December 2014

Extravasation occurs frequently with intravenous infusions. In this case report we describe the occurrence of epidermal detachment and multiple cutaneous bullous eruptions in a patient’s forearm following the extravasation of hydroxyethyl starch (Voluven, Fresenius Kabi)—a colloid solution derived from corn starch, which is used to replace lost blood volume. The patient’s affected body surface area was managed under the direction of our plastic surgical team. Despite a prolonged admission in hospital from other perioperative complications, he made a full recovery and was successfully discharged home. The probable pathogenesis relevant to extravasation of Voluven is discussed; as well as its management principles.
A case of rheumatic valvular heart disease and autoimmune gastritis
Authors: Costa Cátia , Durão David , Peres Marisa , Leal Margarida
Published: December 2014

We present a case of a 50-year-old female patient with a history of depressive disorder and anaemia (attributed to menorrhagias). She was admitted to the cardiology department with symptoms of fatigue on moderate exertion for several months, with worsening in the month before hospitalisation. Echocardiography revealed a severe mitral stenosis of rheumatic aetiology. Laboratory tests showed microcytic and hypochromic anaemia, reduced iron stores and vitamin B12levels, and positive serum antiparietal cells autoantibodies. Endoscopy showed focal areas of erythema in the stomach, corresponding histologically to chronic atrophic gastritis. In this context, two distinct clinical entities were diagnosed in the same patient: severe rheumatic mitral stenosis and autoimmune gastritis. The patient was started on vitamin B12and iron supplementation and underwent surgical correction of the valvular disease. There was symptomatic improvement in her signs of fatigue.
Comparative analysis of alkaline phosphatase-encoding genes (phoX) in two contrasting zones of Lake Taihu
Authors: Dai Jiangyu , Chen Dan , Wu Shiqiang , Wu Xiufeng , Zhou Jie , Tang Xiangming , Shao Keqiang , Gao Guang
Published: December 2014

Limnetic habitats that are dominated by either algae or macrophytes represent the 2 dominant ecosystems in shallow lakes. We assessed seasonal variations in the diversity and abundance of alkaline phosphate-encoding genes (phoX) in these 2 zones of Lake Taihu, which is a large, shallow, eutrophic lake in China. There was no significant difference in seasonal mean phoX diversity between the 2 zones, whereas the seasonal mean phoX abundance in the macrophyte-dominated region was higher than that in the algae-dominated region. The bulk of the genotypes in the 2 regions were most similar to the alphaproteobacterial and betaproteobacterial phoX. Genotypes most similar to phoX affiliated with Betaproteobacteria were present with greater diversity in the macrophyte-dominated zone than in the algae-dominated zone. In the algae-dominated zone, the relative proportion of genotypes most similar to cyanobacterial phoX was highest (38.8%) in summer. In addition to the different genotype structures and environmental factors between the 2 stable states, the lower gene abundances and higher alkaline phosphatase activities in Meiliang Bay in summer than those in Xukou Bay reveals different organophosphate-mineralizing modes in these 2 contrasting habitats.
Sensitivity of the pressure distribution to the fractional order α in the fractional diffusion equation
Authors: Malik Nadeem A. , Ghanam R.A. , Al-Homidan S.
Published: December 2014

In reservoir engineering, an oil reservoir is commonly modeled using Darcy’s diffusion equation for a porous medium. In this work we propose a fractional diffusion equation to model the pressure distribution, p(x, t), of fluid in a horizontal one-dimensional homogeneous porous reservoir of finite length, L, and uniform thickness. A chief concern in this work is to examine the sensitivity of the pressure distribution, p(x, t), to different forms of pseudo-diffusivity, K, including cases when it depends upon the order of the fractional derivative (α), 0 ≤ α < 1 (e.g., K ∝ (1 – α)), which may be more realistic for some types of rock formations. In all cases the systems show a near-linear increase in the pressure difference P(x, t) = (p(x, t) – pi)/pi in the reservoir for large times, where pi = p(x, t = 0). For x/L < 0.4, the rate of increase of P with time increases with α, but there is a crossover at x/L = 0.4 and this trend reverses for x/L > 0.4. When K = 10k (k is the conventional permeability when α = 0), the solutions are almost independent of α, and when K = 0.1k the rate of increase in P depends upon α. This effect is enhanced when K = (1 – α)k; furthermore, in this case towards the closed end of the reservoir the pressure distribution remains practically undisturbed as α → 1. These results show that the pressure distribution in a porous reservoir is very sensitive to the dependence of the pseudo-diffusivity on the order of the fractional derivative, α.
Quarks in the bootstrap era
Authors: Horn D.
Published: December 2014

The quark model emerged from the Gell-Mann–Ne'eman flavor SU(3) symmetry. Its development, in the context of strong interactions, took place in a heuristic theoretical framework, referred to as the Bootstrap Era. Setting the background for the dominant ideas in strong interaction of the early 1960s, we outline some aspects of the constituent quark model. An independent theoretical development was the emergence of hadron duality in 1967, leading to a realization of the Bootstrap idea by relating hadron resonances (in the s-channel) with Regge pole trajectories (in t- and u-channels). The synthesis of duality with the quark-model has been achieved by duality diagrams, serving as a conceptual framework for discussing many aspects of hadron dynamics toward the end of the 1960s.
Brane-induced cosmological acceleration and crossing of weff = -1
Authors: Motoyui Nobuyuki
Published: December 2014

The cosmological observation indicates that the effective equation of state parameter w eff varies with z: it changes from w eff > -1 to w eff < -1 at z~0.2. We investigate under which condition it exhibits such behaviors based on the five-dimensional braneworld scenario. It is possible in the model with or without an energy exchange between the four-dimensional universe and the fifth dimension. However the curves of w eff are quite different between the two cases.
Constraints on the primordial power spectrum of small scales using the neutrino signals from the dark matter decay
Authors: Yang Yupeng
Published: December 2014

Many inflation theories predict that the primordial power spectrum is scale invariant. The amplitude of the power spectrum can be constrained by different observations such as the cosmic microwave background (CMB), Lyman-α, large-scale structures and primordial black holes (PBHs). Although the constraints from the CMB are robust, the corresponding scales are very large (10-4 < k < 1 Mpc -1). For small scales (k > 1 Mpc -1), the research on the PBHs provides much weaker limits. Recently, ultracompact dark matter minihalos (UCMHs) was proposed and it was found that they could be used to constraint the small-scale primordial power spectrum. The limits obtained by the research on the UCMHs are much better than that of PBHs. Most of previous works focus on the dark matter annihilation within the UCMHs, but if the dark matter particles do not annihilate the decay is another important issue. In previous work [Y.-P. Yang, G.-L. Yang and H.-S. Zong, Europhys. Lett.101, 69001 (2013)], we investigated the gamma-ray flux from the UCMHs due to the dark matter decay. In addition to these flux, the neutrinos are usually produced going with the gamma-ray photons especially for the lepton channels. In this work, we studied the neutrino flux from the UCMHs due to the dark matter decay. Finally, we got the constraints on the amplitude of primordial power spectrum of small scales.
Deleting an edge of a 3-cycle in an intrinsically knotted graph gives an intrinsically linked graph
Authors: Naimi Ramin , Pavelescu Elena , Schwartz Hannah
Published: December 2014

We show that deleting an edge of a 3-cycle in an intrinsically knotted graph gives an intrinsically linked graph.
Knowledge Audit Approach for a Large-Scale Government KM Strategy
Authors: Roy Marie-Christine , Mosconi Elaine , Sager Mireille , Ricard Jean-Francois
Published: December 2014

The promise of increased organizational performance has brought about a high level of interest for knowledge management (KM). Organizations and Governments are also actively launching KM projects to meet increasing needs of high quality and responsiveness. This interest has contributed to the development of various aspects of KM, but has also underscored a lack of effective methods, as evidenced by the sheer number of proposed approaches, along with a lingering scepticism about their relevance in practice. In this article, we argue for the necessity for a more global and high level analysis for orienting KM strategic planning and propose different steps to go about it. We used an action research approach in the context of Quebec's efforts in planning a global and integrated KM strategy for managing its water related knowledge. This research project shows that the proposed auditing approach provided a useful guide to identify critical issues and projects in KM planning, particularly in a complex and large-scale governmental environment.
Yang–Mills connections on compact complex tori
Authors: Biswas Indranil
Published: December 2014

Let G be a connected reductive complex affine algebraic group and K ⊂ G a maximal compact subgroup. Let M be a compact complex torus equipped with a flat Kähler structure and (EG, θ) a polystable Higgs G-bundle on M. Take any C∞ reduction of structure group EK ⊂ EG to the subgroup K that solves the Yang–Mills equation for (EG, θ). We prove that the principal G-bundle EG is polystable and the above reduction EK solves the Einstein–Hermitian equation for EG. We also prove that for a semistable (respectively, polystable) Higgs G-bundle (EG, θ) on a compact connected Calabi–Yau manifold, the underlying principal G-bundle EG is semistable (respectively, polystable).
Finite element analysis of piping defect formation in the sheet-extrusion process
Authors: Phanitwong Wiriyakorn , Thipprakmas Sutasn
Published: December 2014

The pressing process, as compared to the machining process, makes good utilization of work piece material and shortens the production time, and as such it is increasingly used for production of complex shaped parts. A particular type of pressing is sheet-extrusion which controls the flow of material into special punch and die sets to produce an extruded shape. However, some particularly complex shaped parts cannot be made by sheet-extrusion due to the formation of piping defects. In this study, the finite element method (FEM) was used to investigate the formation of piping defects. In addition, the relationship between the characteristic dimensions of the extruded shape and the piping defect was also examined. Laboratory pressing experiments were performed to validate the accuracy of the FEM simulation results. Based on the stress distribution and velocity profiles within the extruded work piece, the relationship between the extruded shape and the piping defect was clearly identified. Furthermore, the FEM simulation results showed good agreement with the experimental results with regards to the dimensions of the extruded shape and the piping defect.
Pronunciation Variants Prediction Method to Detect Mispronunciations by Korean Learners of English
Authors: Bang Jeesoo , Lee Jonghoon , Lee Gary Geunbae , Chung Minhwa
Published: December 2014

This article presents an approach to nonnative pronunciation variants modeling and prediction. The pronunciation variants prediction method was developed by generalized transformation-based error-driven learning (GTBL). The modified goodness of pronunciation (GOP) score was applied to effective mispronunciation detection using logistic regression machine learning under the pronunciation variants prediction. English-read speech data uttered by Korean-speaking learners of English were collected, then pronunciation variation knowledge was extracted from the differences between the canonical phonemes and the actual phonemes of the speech data. With this knowledge, an error-driven learning approach was designed that automatically learns phoneme variation rules from phoneme-level transcriptions. The learned rules generate an extended recognition network to detect mispronunciations. Three different mispronunciation detection methods were tested including our logistic regression machine learning method with modified GOP scores and mispronunciation preference features; all three methods yielded significant improvement in predictions of pronunciation variants, and our logistic regression method showed the best performance.
Efficient Personalized Probabilistic Retrieval of Chinese Calligraphic Manuscript Images in Mobile Cloud Environment
Authors: Zhuang Yi , Li Qing , Chiu Dickson K. W. , Wu Zhiang , Hu Haiyang
Published: December 2014

Ancient language manuscripts constitute a key part of the cultural heritage of mankind. As one of the most important languages, Chinese historical calligraphy work has contributed to not only the Chinese cultural heritage but also the world civilization at large, especially for Asia. To support deeper and more convenient appreciation of Chinese calligraphy works, based on our previous work on the probabilistic retrieval of historical Chinese calligraphic character manuscripts repositories, we propose a system framework of the multi-feature-based Chinese calligraphic character images probabilistic retrieval in the mobile cloud network environment, which is called the
DPRC
. To ensure retrieval efficiency, we further propose four enabling techniques: (1) DRL-based probability propagation, (2) optimal data placement scheme, (3) adaptive data robust transmission algorithm, and (4) index support filtering scheme. Comprehensive experiments are conducted to testify the effectiveness and efficiency of our proposed
DPRC
method.
Cloud Computing
Authors: Mastelic Toni , Oleksiak Ariel , Claussen Holger , Brandic Ivona , Pierson Jean-Marc , Vasilakos Athanasios V.
Published: December 2014

Cloud computing is today’s most emphasized Information and Communications Technology (ICT) paradigm that is directly or indirectly used by almost every online user. However, such great significance comes with the support of a great infrastructure that includes large data centers comprising thousands of server units and other supporting equipment. Their share in power consumption generates between 1.1% and 1.5% of the total electricity use worldwide and is projected to rise even more. Such alarming numbers demand rethinking the energy efficiency of such infrastructures. However, before making any changes to infrastructure, an analysis of the current status is required. In this article, we perform a comprehensive analysis of an infrastructure supporting the cloud computing paradigm with regards to energy efficiency. First, we define a systematic approach for analyzing the energy efficiency of most important data center domains, including server and network equipment, as well as cloud management systems and appliances consisting of a software utilized by end users. Second, we utilize this approach for analyzing available scientific and industrial literature on state-of-the-art practices in data centers and their equipment. Finally, we extract existing challenges and highlight future research directions.
Rich Vehicle Routing Problem
Authors: Caceres-Cruz Jose , Arias Pol , Guimarans Daniel , Riera Daniel , Juan Angel A.
Published: December 2014

The Vehicle Routing Problem (VRP) is a well-known research line in the optimization research community. Its different basic variants have been widely explored in the literature. Even though it has been studied for years, the research around it is still very active. The new tendency is mainly focused on applying this study case to real-life problems. Due to this trend, the Rich VRP arises: combining multiple constraints for tackling realistic problems. Nowadays, some studies have considered specific combinations of real-life constraints to define the emerging Rich VRP scopes. This work surveys the state of the art in the field, summarizing problem combinations, constraints defined, and approaches found.
On Computing Mapping of 3D Objects
Authors: Li Xin , Iyengar S. S.
Published: December 2014

We review the computation of 3D geometric data mapping, which establishes one-to-one correspondence between or among spatial/spatiotemporal objects. Effective mapping benefits many scientific and engineering tasks that involve the modeling and processing of correlated geometric or image data. We model mapping computation as an optimization problem with certain geometric constraints and go through its general solving pipeline. Different mapping algorithms are discussed and compared according to their formulations of objective functions, constraints, and optimization strategies.
Generalizing causal knowledge
Authors: Bareinboim Elias , Pearl Judea
Published: December 2014

This article is a short summary of the full dissertation thesis that was defended in 2014 at the University of California, Los Angeles.
Immunostimulatory Activity of Protein Hydrolysate from Oviductus Ranae on Macrophage In Vitro
Authors: Huang Di , Yang Lubing , Wang Chenlu , Ma Sihui , Cui Li , Huang Shiyang , Sheng Xia , Weng Qiang , Xu Meiyu
Published: December 2014

Oviductus Ranae is the dry oviduct of Rana chensinensis, which is also called R. chensinensis oil. Oviductus Ranae is a valuable Chinese crude drug and is recorded in the Pharmacopoeia of the People’s Republic of China. The aim of this study was to investigate the immunostimulatory activity of protein hydrolysate of Oviductus Ranae (ORPH) and to assess its possible mechanism. Immunomodulatory activity of ORPH was examined in murine macrophage RAW 264.7 cells. The effect of ORPH on the phagocytic activity of macrophages was determined by the neutral red uptake assay. After treatment with ORPH, NO production levels in the culture supernatant were investigated by Griess assay. The mRNA and protein expressions of inducible nitric oxide synthase (iNOS) were detected by RT‐PCR and Western blotting. The production of TNF‐α, IL‐1β, and IL‐6 after treatment with ORPH was measured using ELISA assay. In addition, NF‐κB levels were also investigated by Western blot. The results showed that ORPH enhanced the phagocytosis of macrophage, increased productions of TNF‐α, IL‐1β, IL‐6, and NO in RAW 264.7 cells, and upregulated the mRNA and protein expression of iNOS. Besides, NF‐κB, levels in RAW 264.7 cells were elevated after ORPH treatment. These findings suggested that ORPH might stimulate macrophage activities by activating the NF‐κB pathway.