bluuebunny/crossref_metadata_2025_split huggingface dataset:
Velocity Field and Energy Dissipation in Viscoplastic Flow in Tubes of Non-Circular Cross-Section
Authors: Letelier Mario F. , Siginer Dennis A. , Godoy Felipe 
Published: June 2016

An analytical method for determining the velocity field, shear stress and energy dissipation in viscoplastic flow in non-circular straight tubes is presented. Bingham’s model of fluid is used for the case of tubes with several cross-sectional contours that can be arbitrarily chosen through a shape factor imposed in the solution for the longitudinal velocity. The analysis is extended to steady flow in tubes in which the cross-section contour exhibits sharp corners. In these cases three flow zones are distinguished: stagnant, non-zero deformation, and plug zones. The method provides the expressions for determining the boundaries and characteristics of those three zones for a wide variety of cross-section shapes. In particular the dynamics of plug-zones for large values of the yield stress and for contours that markedly differ from circumferences is analyzed. Energy dissipation is determined throughout the entire cross-section, so that the effect of shape on mechanical energy loss is assessed in terms of the yield stress and viscosity of the fluid. Some general expressions that help understand energy dissipation mechanisms are derived by using natural coordinates for the velocity field and related variables.
These results draw on several recent works from other researchers and the present authors, which have highlighted the significant difficulty of determining the zones of zero deformation in viscoplastic flow when the related solid boundaries are not elementary.
Numerical Study of Drag Forces in Gravity-Induced Separation for Water Dominated Dispersed Oil-Water
Authors: Caldera Elionora A. , Asuaje Miguel 
Published: June 2016

In recent years, the oil sector has been struggling with the amount of water produced associated with the total volume of oil production. This quantity is known as water cut and could be over 90% in oil extraction. Handling of this water generates additional costs, affecting the sector’s revenues. In order to solve this problem, several techniques to reduce water cut in the wellbore have been applied.
This paper evaluates CFD (computational fluid dynamics) models to predict phase segregation in dispersed oil in water flows. This evaluation has been conducted in an attempt to use CFD models to improve the design methodology of an inline separator of oil-water flow for petroleum production systems [1].
In this 3D study, three cases simulating water dominated dispersed oil-water flow in an inclined pipe 45° from horizontal, were evaluated numerically using a CFD model The oil was considered as the disperse phase and the water as the continuous phase, using Ansys®CFX. Mono size droplet dispersion was employed to represent the dispersed phase. The equations for the forces considered in this study are: drag and buoyancy.
The simulated results are compared with the experimental data, which includes water volume fraction, drop pressure and separation efficiency. The result shows an improvement of over 50% in the experimental values, which match the values of the total flow rate (Q), water holdup (Hw) and pressure drop (ΔP), deviating by less than 4%.
Fiber Supplemented Droplet Diving Into Two Liquid Layers
Authors: Harris Alyssa , Su Tsung-chow 
Published: June 2016

In an exploratory experiment, utilizing a flow visualization technique, a droplet of water was supplemented with fiber and released into a container of liquid. The liquid inside container consisted of a thin layer of oil laid on top of the water, in which a small amount of bromothymol-blue indicator was added. The liquid droplet also contained a dilute solution of NaOH along with the small amount of fiber supplement. Thus, as the droplet dived through the two immiscible layers, the path of the diffused droplet exhibited a dark blue color due to its greater pH.
It was found that due to the weight of the added fiber, the drop began to form an inverted mushroom. Then, the weight continues to pull the droplet to the bottom of the container where the fiber-enhanced liquid rotates in a circular path. A portion of fiber remains latched onto the oil layer, which sustains the diffusing fiber stretching into a single, straight line filament. Yet, over time the straight filament began to buckle and bend. Over time, the droplet became increasingly unstable prior returning to a single filament once more. This transformation was evidenced until the deep blue faded as the pH level diffused. An additional experiment was carried out using a larger droplet. The droplet with a larger surface area reacted similarly, but passed the oil/ water interface at multiple contact points, as opposed to a sole point. Subsequently, multiple bending filaments appeared in the liquid. In time these filaments combined into a distinct, deformed, filament. After which, the continued instability of the filament broke into two segments, that with time became orderly. In the end, a pair of filaments was formed from the larger fiber-laced droplet.
The idea of controlling drug delivery has been studied from a plethora of angles, however, how a drug diffuses with the addition of fiber has not often been visualized. This visual investigation will establish the fundamental physics that is a critical first step in the ability to understand, predict and control the motion of a fiber enriched liquid droplet releasing into another liquid. It is of fundamental importance to the medical field and beyond if the addition of a fiber solution can influence medicine, or a solution, to reach a particular location.
Further research on this topic would involve the effect of fluid viscosity and surface tension to improve drug delivery.
Theoretical and Experimental Study of Hydrocyclone Performance and Equivalent Settling Area
Authors: Sabbagh Reza , Lipsett Michael G. , Koch Charles R. , Nobes David S. 
Published: June 2016

Predicting the performance of a solid-liquid separation process can help in comparing different separators for selection and design. This can be applied to hydrocyclone technology which is used widely in industry due to being an inexpensive device that is easy to operate and maintain and which has no moving parts. Environmental concerns and technological issues in separation processes are motivating the design of higher efficiency systems with less capital and operating costs. There is a need therefore for, methods to compare different separation technologies.
In spite of extensive research into hydrocyclone performance, a mathematical model that can predict the performance of a hydrocyclone for comparison with other centrifugal separators is rare in the literature. The main objective of this research is to apply theoretical and experimental approaches to study hydrocyclone performance in order to propose an applicable separation performance model that represents the whole hydrocyclone operating range. A mathematical model is developed to explore the performance of the separator and to predict the hydrocyclone’s equivalent area as compared to a continuous gravity settling tank. A performance chart that can be used for selection and design of hydrocyclones is the result of the model.
Wake Alleviating Devices for Offshore Wind Turbines
Authors: Klimchenko Vera 
Published: June 2016

The wake behind an offshore wind turbine can persist for several turbine diameters, so decreasing the space between wind turbines in an array leads to strong wake-turbine interactions and a decrease in efficiency of the wind turbines downstream. The dominant structures in the wake of a horizontal axis wind turbine are large helical tip vortices. Implementing devices on the blade tips of a wind turbine can induce mixing into the tip vortex core, encouraging breakup of the tip vortices and wake dissipation. A wake that dissipated more quickly can maximize the farm-level efficiency by allowing more turbines to be installed in a fixed area.
This study focuses on quantifying the effectiveness of three different blade-mounted devices in speeding up the dissipation of the wake of an offshore horizontal axis wind turbine. Experiments were conducted in a low speed, low turbulence wind tunnel. A small scale wind turbine model was designed using optimum rotor theory to match the tip speed ratio of an offshore wind turbine. The baseline case consisted of a wind turbine rotor without blade-mounted devices. It was tested in the wind tunnel under a range of free stream conditions, and the rotational speed was measured to determine the operational tip speed ratios. A second test case was the same rotor, but with winglets at the blade tips designed to weaken the tip vortices. A third test case was the baseline case rotor with serrated blade tips, designed to introduce turbulence into the core of the tip vortex. Smoke flow visualization and particle image velocimetry (PIV) were used to observe the dissipation of the turbines’ wake. The effectiveness of the blade-mounted devices on wake dissipation was evaluated with a special interest in optimizing the overall energy harvested by an offshore wind farm of a fixed area. It was shown that both tip treatments tested have the capacity to reenergize the flow and decrease the momentum deficit in the wake of a wind turbine.
Experimental Measurements and Flow Visualization of Water Cavitation Through a Nozzle
Authors: Wilms Jeffrey , Beck Terry , Sorensen Christopher M. , Hosni Mohammad H. , Eckels Steven J. , Tomasi Don 
Published: June 2016

A typical refrigeration loop is composed of an evaporator, compressor, condenser, and an expansion valve. There are many possible refrigerants that can be used, but the physical properties of water make it ineffective in the traditional refrigeration loop. But if water could be used it would have many advantages as it is abundant, cheap, and is safe for the environment. As part of development of a new refrigeration loop using water, flow visualization and cavitation of water through nozzles are being investigated. Cavitation is generally defined as creating vapor from liquid, not through adding heat, but by decreasing the pressure. In a converging/ diverging nozzle as the cross sectional area is constricted the velocity of the flow will increase, decreasing the pressure. Therefore, by flowing water through the nozzle it will cavitate. Transforming liquid into gas requires a certain amount of energy, defined as the latent heat. When a liquid is turned to vapor by an increase in the temperature the latent heat is provided by the heat transfer to the system. As no energy is being added in the nozzle to cause the cavitation, the heat to create the vapor comes from the liquid, effectively causes a temperature drop.
This article presents results for the flow visualization of the water cavitating as it goes through the nozzle. Under different flow conditions and nozzle geometries the cavitation manifested itself in different formations. When gasses were entrained in the water they formed bubbles, creating a nucleation site and moving through the nozzle, called travelling bubble cavitation. In venturi nozzles the cavitation nucleated off of the wall, forming attached wall cavitation. When water flowed out of an orifice, a turbulent water jet was formed which caused vapor to form around it, causing shear cavitation. When the water was rotated prior to the throat of an orifice, the orifice jet expanded radially and formed swirl cavitation.
Summary and Recommendations from the National Institute of Allergy and Infectious Diseases (NIAID) Workshop “Gonorrhea Vaccines: the Way Forward”
Authors: Wetzler Lee M. , Feavers Ian M. , Gray-Owen Scott D. , Jerse Ann E. , Rice Peter A. , Deal Carolyn D. 
Published: June 2016

ABSTRACT

There is an urgent need for the development of an antigonococcal vaccine due to the increasing drug resistance found in this pathogen. The U.S. Centers for Disease Control (CDC) have identified multidrug-resistant gonococci (GC) as among 3 “urgent” hazard-level threats to the U.S. population. In light of this, on 29 to 30 June 2015, the National Institute for Allergy and Infectious Diseases (NIAID) sponsored a workshop entitled “Gonorrhea Vaccines: the Way Forward.” The goal of the workshop was to gather leaders in the field to discuss several key questions on the current status of gonorrhea vaccine research and the path forward to a licensed gonorrhea vaccine. Representatives from academia, industry, U.S. Government agencies, and a state health department were in attendance. This review summarizes each of the 4 scientific sessions and a series of 4 breakout sessions that occurred during the one and a half days of the workshop. Topics raised as high priority for future development included (i) reinvigoration of basic research to understand gonococcal infection and immunity to allow intervention in processes essential for infection; (ii) clinical infection studies to establish parallels and distinctions between
in vitro
and animal infection models versus natural human genital and pharyngeal infection and to inform
in silico
modeling of vaccine impact; and (iii) development of an integrated pipeline for preclinical and early clinical evaluation and direct comparisons of potential vaccine antigens and adjuvants and routes of delivery.
Live Attenuated Borrelia burgdorferi Targeted Mutants in an Infectious Strain Background Protect Mice from Challenge Infection
Authors: Hahn Beth L. , Padmore Lavinia J. , Ristow Laura C. , Curtis Michael W. , Coburn Jenifer 
Published: June 2016

ABSTRACT

Borrelia burgdorferi
,
B. garinii
, and
B. afzelii
are all agents of Lyme disease in different geographic locations. If left untreated, Lyme disease can cause significant and long-term morbidity, which may continue after appropriate antibiotic therapy has been administered and live bacteria are no longer detectable. The increasing incidence and geographic spread of Lyme disease are renewing interest in the vaccination of at-risk populations. We took the approach of vaccinating mice with two targeted mutant strains of
B. burgdorferi
that, unlike the parental strain, are avirulent in mice. Mice vaccinated with both strains were protected against a challenge with the parental strain and a heterologous
B. burgdorferi
strain by either needle inoculation or tick bite. In ticks, the homologous strain was eliminated but the heterologous strain was not, suggesting that the vaccines generated a response to antigens that are produced by the bacteria both early in mammalian infection and in the tick. Partial protection against
B. garinii
infection was also conferred. Protection was antibody mediated, and reactivity to a variety of proteins was observed. These experiments suggest that live attenuated
B. burgdorferi
strains may be informative regarding the identification of protective antigens produced by the bacteria and recognized by the mouse immune system
in vivo
. Further work may illuminate new candidates that are effective and safe for the development of Lyme disease vaccines.
Study protocol for a pilot, randomised, double-blinded, placebo controlled trial of perineural local anaesthetics and steroids for chronic post-traumatic neuropathic pain in the ankle and foot: the PREPLANS study
Authors: Bhatia Anuj , Bril Vera , Brull Richard T , Perruccio Anthony , Wijeysundera Duminda , Alvi Sabbeh , Lau Johnny , Gandhi Rajiv , Mahomed Nizar , Davis Aileen M 
Published: June 2016

IntroductionPeripheral neuropathic pain (PNP) associated with trauma is often refractory to treatment. Administration of local anaesthetics (LA) and steroids around injured nerves has been proposed as an option for patients unresponsive to conventional treatments for refractory PNP following trauma. There is insufficient evidence to support a large, potentially expensive, full-scale randomised controlled trial (RCT) that involves comparison of effects of perineural steroids and LA against LA or saline injections on analgesia, physical and psychological functioning, and quality of life. There is also a lack of data that would allow estimation of analgesic efficacy or sample size for the full-scale RCT. The objective of this pilot RCT is to yield information to support planning of a full-scale RCT in this population.Methods and Analysis30 participants with post-traumatic PNP in the ankle and foot of moderate-to-severe intensity and duration of more than 3 months will be enrolled in this pilot RCT. Participants will be randomised to receive three ultrasound-guided perineural injections of 0.9% saline, 0.25% bupivacaine (a long-acting LA) or a combination of 0.25% bupivacaine and a steroid (methylprednisolone 16 mg per nerve) at weekly intervals. The primary objectives are to determine the feasibility and sample size of a full-scale RCT in this population. The secondary objectives are to evaluate the effect of study interventions on analgesia, persistence of neuropathic pain, psychological and physical function, quality of life and participants' global impression of change at 1 and 3 months after the interventions. In addition, adverse effects associated with perineural injections and with systemic absorption of steroids will also be recorded.Ethics and DisseminationThe protocol was approved by the University Health Network Research Ethics Board (UHN REB number 15-9584-A). The results will be disseminated in peer-reviewed journals and at scientific conferences.Trial registration numberNCT02680548; Pre-results.
Developing psychological services following facial trauma
Authors: Choudhury-Peters Deba , Dain Vicky 
Published: June 2016

Adults presenting to oral and maxillofacial surgery services are at high risk of psychological morbidity. Research by the Institute of Psychotrauma and the centre for oral and maxillofacial surgery trauma clinic at the Royal London hospital (2015) demonstrated nearly 40% of patients met diagnostic criteria for either depression, post traumatic stress disorder (PTSD), anxiety, alcohol misuse, or substance misuse, or were presenting with facial appearance distress. Most facial injury patients were not receiving mental health assessment or treatment, and the maxillofacial team did not have direct access to psychological services. Based on these research findings, an innovative one-year pilot psychology service was designed and implemented within the facial trauma clinic.The project addressed this need by offering collaborative medical and psychological care for all facial injury patients. The project provided brief screening, assessment, and early psychological intervention. The medical team were trained to better recognise and respond to psychological distress.
Burden of emergency conditions and emergency care usage: new estimates from 40 countries
Authors: Chang Cindy Y , Abujaber Samer , Reynolds Teri A , Camargo Carlos A , Obermeyer Ziad 
Published: June 2016

ObjectiveTo estimate the global and national burden of emergency conditions, and compare them to emergency care usage rates.MethodsWe coded all 291 Global Burden of Disease 2010 conditions into three categories to estimate emergency burden: conditions that, if not addressed within hours to days of onset, commonly lead to serious disability or death; conditions with common acute decompensations that lead to serious disability or death; and non-emergencies. Emergency care usage rates were obtained from a systematic literature review on emergency care facilities in low-income and middle-income countries (LMICs), supplemented by national health system reports.FindingsAll 15 leading causes of death and disability-adjusted life years (DALYs) globally were conditions with potential emergent manifestations. We identified 41 facility-based reports in 23 countries, 12 of which were in LMICs; data for 17 additional countries were obtained from national or regional reports on emergency usage. Burden of emergency conditions was the highest in low-income countries, with median DALYs of 47 728 per 100 000 population (IQR 45 253–50 085) in low-income, 25 186 (IQR 21 982–40 480) in middle-income and 15 691 (IQR 14 649–16 382) in high-income countries. Patterns were similar using deaths to measure burden and excluding acute decompensations from the definition of emergency conditions. Conversely, emergency usage rates were the lowest in low-income countries, with median 8 visits per 1000 population (IQR 6–10), 78 (IQR 25–197) in middle-income and 264 (IQR 177–341) in high-income countries.ConclusionsDespite higher burden of emergency conditions, emergency usage rates are substantially lower in LMICs, likely due to limited access to emergency care.
Spectrum of area in the Faddeev formulation of gravity
Authors: Khatsymovsky V. M. 
Published: June 2016

Faddeev formulation of general relativity (GR) is considered where the metric is composed of ten vector fields or a ten-dimensional tetrad. Upon partial use of the field equations, this theory results in the usual general relativity (GR). Earlier, we have proposed first-order representation of the minisuperspace model for the Faddeev formulation where the tetrad fields are piecewise constant on the polytopes like four-simplices or, say, cuboids into which [Formula: see text] can be decomposed, an analogue of the Cartan–Weyl connection-type form of the Hilbert–Einstein action in the usual continuum GR. In the Hamiltonian formalism, the tetrad bilinears are canonically conjugate to the orthogonal connection matrices. We evaluate the spectrum of the elementary areas, functions of the tetrad bilinears. The spectrum is discrete and proportional to the Faddeev analog [Formula: see text] of the Barbero–Immirzi parameter [Formula: see text]. The possibility of the tetrad and metric discontinuities in the Faddeev gravity allows to consider any surface as consisting of a set of virtually independent elementary areas and its spectrum being the sum of the elementary spectra. Requiring consistency of the black hole entropy calculations known in the literature we are able to estimate [Formula: see text].
DESIGN AND ANALYSIS OF AN STATIC AEROELASTIC EXPERIMENT
Authors: HOU YING-YU , YUAN KAI-HUA , LV JI-NAN , LIU ZI-QIANG 
Published: June 2016

Static aeroelastic experiments are very common in the United States and Russia. The objective of static aeroelastic experiments is to investigate deformation and loads of elastic structure in flow field. Generally speaking, prerequisite of this experiment is that the stiffness distribution of structure is known. This paper describes a method for designing experimental models, in the case where the stiffness distribution and boundary condition of a real aircraft are both uncertain. The stiffness distribution form of the structure can be calculated via finite element modeling and simulation calculation and F141 steels and rigid foam are used to make elastic model. In this paper, the design and manufacturing process of static aeroelastic models is presented and a set of experiment model was designed to simulate the stiffness of the designed wings, a set of experiments was designed to check the results. The test results show that the experimental method can effectively complete the design work of elastic model. This paper introduces the whole process of the static aeroelastic experiment, and the experimental results are analyzed. This paper developed a static aeroelasticity experiment technique and established an experiment model targeting at the swept wing of a certain kind of large aspect ratio aircraft.