WorldWideScience

Sample records for critical regimen multiphase

  1. Implementation of leak detection techniques in ducts with critical regimen multiphase flow; Implementacao de tecnicas de deteccao de vazamentos em dutos em regime de escoamento multifasico critico

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Rodrigo S.; Maitelli, Andr L.; Doria Neto, Adriao D.; Salazar, Andres O. [Rio Grande do Norte Univ., Natal, RN (Brazil)

    2005-07-01

    This paper presents signals processing techniques and artificial neural networks to identify leaks in multiphase flow pipeline. The greatest difficulty on traditional methods of leak detection (volume balance, pressure point analysis, etc) is that they are insufficient to design an adequate profile for the real conditions of oil pipeline transport. These difficult conditions goes since unevenly soil, that cause columns or vacuum throughout pipelines, until the presence of multi phases like water, gas and oil; plus other components as sand, which use to produce discontinuous flow off and diverse variations. To attenuate these difficulties, the transform wavelet was used to map the signal pressure in different resolution plan allowing the extraction of descriptors that identify leaks patterns and with then to provide training for the neural network multilayer perceptron (MLP) to learning of how to classify this pattern and report whenever this characterize leaks. During the tests were used transient and regime signals and pipelines with punctures with size variations from 1/2'' to 1'' of diameter to simulate leaks and, this way, it was possible to detect leaks with a time window of two minutes. The result show that the proposed descriptors considered, based in statistical methods applied in domain transform, are sufficient to identify leaks patterns and make it possible to train the neural classifier to indicate the occurrence of pipeline leaks. (author)

  2. Multiphase forces on bend structures – critical gas fraction for transition single phase gas to multiphase flow behaviour

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Nennie, E.D.; Lewis, M.

    2016-01-01

    Piping structures are generally subjected to high dynamic loading due to multiphase forces. In particular subsea structures are very vulnerable as large flexibility is required to cope for instance with thermal stresses. The forces due to multiphase flow are characterized by a broadband spectrum wit

  3. Multiphase forces on bend structures – critical gas fraction for transition single phase gas to multiphase flow behaviour

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Nennie, E.D.; Lewis, M.

    2016-01-01

    Piping structures are generally subjected to high dynamic loading due to multiphase forces. In particular subsea structures are very vulnerable as large flexibility is required to cope for instance with thermal stresses. The forces due to multiphase flow are characterized by a broadband spectrum wit

  4. Insights into prolonged solution criticality incidents, using the coupled radiation/multiphase code FETCH

    Energy Technology Data Exchange (ETDEWEB)

    Pain, C.C.; Oliveira, C.R.E. de; Goddard, A.J.H. [T.H. Huxley School of the Environment, Earth Sciences and Engineering, Imperial College, London (United Kingdom)

    2000-12-01

    The development of the FETCH transient code has been supported by the UK regulator, the Nuclear Installations Inspectorate, as a generic reference method for modelling fissile solution criticality. The fundamental basis of the method means that it can be applied to situations somewhat beyond the range of available experiment. General geometry finite-element modelling is used for the two linked modules: neutron transport and multiphase computational fluid dynamics. Multiphase modelling includes bubble dynamics, free surface motion (sloshing) and the ability to calculate pressure waves and their interaction with bubble formation. FETCH has been benchmarked against transient power and pressure results from the SILENE experiments and is being tested against published TRACY measurements. Research is being performed in order to use data from the incident at the JCO Company on 30-31 September 1999 to: (a) gain an understanding of the mechanism of criticality to improve the future safety designs of the fuel cycle facilities; and (b) to understand the mechanisms of this accident itself, for example its prolonged nature. The full published geometry of the 'sedimentation tank' has been modelled focusing on, firstly, the role of the assumed initial conditions, such as filling rate. The influence of heat removal rate upon the power during prolonged criticality phase is demonstrated. The paper comments on the role that pressure might have in influencing the consequences of criticality accidents. (author)

  5. Multiphase Binary Mixture Flows in Porous Media in a Wide Pressure and Temperature Range Including Critical Conditions

    Science.gov (United States)

    Afanasyev, A.

    2011-12-01

    Multiphase flows in porous media with a transition between sub- and supercritical thermodynamic conditions occur in many natural and technological processes (e.g. in deep regions of geothermal reservoirs where temperature reaches critical point of water or in gas-condensate fields where subject to critical conditions retrograde condensation occurs and even in underground carbon dioxide sequestration processes at high formation pressure). Simulation of these processes is complicated due to degeneration of conservation laws under critical conditions and requires non-classical mathematical models and methods. A new mathematical model is proposed for efficient simulation of binary mixture flows in a wide range of pressures and temperatures that includes critical conditions. The distinctive feature of the model lies in the methodology for mixture properties determination. Transport equations and Darcy law are solved together with calculation of the entropy maximum that is reached in thermodynamic equilibrium and determines mixture composition. To define and solve the problem only one function - mixture thermodynamic potential - is required. Such approach allows determination not only single-phase states and two-phase states of liquid-gas type as in classical models but also two-phase states of liquid-liquid type and three-phase states. The proposed mixture model was implemented in MUFITS (Multiphase Filtration Transport Simulator) code for hydrodynamic simulations. As opposed to classical approaches pressure, enthalpy and composition variables together with fully implicit method and cascade procedure are used. The code is capable of unstructured grids, heterogeneous porous media, relative permeability and capillary pressure dependence on temperature and pressure, multiphase diffusion, optional number of sink and sources, etc. There is an additional module for mixture properties specification. The starting point for the simulation is a cubic equation of state that is

  6. A specially tailored vancomycin continuous infusion regimen for renally impaired critically ill patients

    Directory of Open Access Journals (Sweden)

    Eman Mohamed Bahgat Eldemiry

    2013-10-01

    Full Text Available Background: Vancomycin remains the gold standard for treatment of methicillin-resistant Staphylococcus aureus. Specially designed continuous infusion of vancomycin leads to better therapy. Methodology: A total of 40 critically ill patients who suffered from pneumonia susceptible to vancomycin, had serum creatinine >1.4 mg%, and oliguria <0.5 mL/kg/h for 6 h were included in the study with respiratory culture sensitivity to vancomycin ≤2 mg/L. Patients’ clinical, microbiological, and biological data were obtained by retrospective analysis of the corresponding medical files before and after vancomycin treatment. Patients with serum creatinine level ≥4 mg% and patients who received renal replacement therapy during the treatment period were excluded. The patients were divided into two groups—group 1 (intermittent dosing and group 2 (continuous infusion based on the following formula: rate of vancomycin continuous infusion (g/day = [0.0205 creatinine clearance (mL/min + 3.47] × [target vancomycin concentration at steady state (µg/mL] × (24/1000. Trough vancomycin serum levels were also assessed using high-performance liquid chromatographic technique. Patients’ outcomes such as clinical improvement, adverse events, and 15-day mortality were reported. Results: Group 2 showed significant reduction in blood urea nitrogen, creatinine serum levels, white blood cells, partial carbon dioxide pressure, body temperature, and Sequential Organ Failure Assessment score, while significant increase in partial oxygen pressure and saturated oxygen was also observed. A significantly shorter duration of treatment with a comparable vancomycin serum levels was also reported with group 2. Conclusion: After treatment, comparison in patients’ criteria supports the superiority of using continuous infusion of vancomycin according to this equation in renally impaired patients.

  7. Toward an Evidence-Based Nonclinical Road Map for Evaluating the Efficacy of New Tuberculosis (TB) Drug Regimens: Proceedings of a Critical Path to TB Drug Regimens-National Institute of Allergy and Infectious Diseases In Vivo Pharmacology Workshop for TB Drug Development

    Science.gov (United States)

    Nuermberger, Eric; Sizemore, Christine; Romero, Klaus

    2016-01-01

    Novel tuberculosis (TB) drug regimens are urgently needed, and their development will be enabled by improved preclinical approaches that more effectively inform and ensure safe selection of clinical candidates and drug combination/regimens. An evidence-based approach for the assessment of nonclinical models supporting TB drug development has been proposed by a joint partnership between the National Institute of Allergy and Infectious Diseases (NIAID) and the Critical Path to TB Drug Regimens (CPTR) Consortium. PMID:26824941

  8. Toward an Evidence-Based Nonclinical Road Map for Evaluating the Efficacy of New Tuberculosis (TB) Drug Regimens: Proceedings of a Critical Path to TB Drug Regimens-National Institute of Allergy and Infectious Diseases In Vivo Pharmacology Workshop for TB Drug Development

    OpenAIRE

    Nuermberger, Eric; Sizemore, Christine; Romero, Klaus; Hanna, Debra

    2016-01-01

    Novel tuberculosis (TB) drug regimens are urgently needed, and their development will be enabled by improved preclinical approaches that more effectively inform and ensure safe selection of clinical candidates and drug combination/regimens. An evidence-based approach for the assessment of nonclinical models supporting TB drug development has been proposed by a joint partnership between the National Institute of Allergy and Infectious Diseases (NIAID) and the Critical Path to TB Drug Regimens ...

  9. Efficacy of basal-bolus insulin regimens in the inpatient management of non-critically ill patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Christensen, Merete B; Gotfredsen, Anders; Nørgaard, Kirsten

    2017-01-01

    BACKGROUND: Hyperglycemia during hospitalization is associated with increased rates of complications and longer hospital stays. Various insulin regimens are used in the inpatient diabetes management of non-critically ill patients. We aimed to assess the efficacy and safety of basal-bolus insulin...... therapy (BBI) by summarizing evidence from studies of BBI versus sliding scale insulin therapy (SSI) in the management of hospitalized non-critically ill type 2 diabetes patients. METHODS: We searched MEDLINE, EMBASE, Scopus and the Cochrane Library for studies comparing BBI therapy with SSI therapy...... in hospitalized non-critically ill patients with type 2 diabetes. Primary outcome was mean daily blood glucose (BG) during admission. Secondary outcomes were incidence of hypoglycemia and length of hospital stay. Results of included randomized controlled trials (RCT) were pooled and meta-analyzed to provide...

  10. Modeling multiphase materials processes

    CERN Document Server

    Iguchi, Manabu

    2010-01-01

    ""Modeling Multiphase Materials Processes: Gas-Liquid Systems"" describes the methodology and application of physical and mathematical modeling to multi-phase flow phenomena in materials processing. The book focuses on systems involving gas-liquid interaction, the most prevalent in current metallurgical processes. The performance characteristics of these processes are largely dependent on transport phenomena. This volume covers the inherent characteristics that complicate the modeling of transport phenomena in such systems, including complex multiphase structure, intense turbulence, opacity of

  11. Initial dosing regimen of vancomycin to achieve early therapeutic plasma concentration in critically ill patients with MRSA infection based on APACHE II score.

    Science.gov (United States)

    Imaura, Masaharu; Yokoyama, Haruko; Kohata, Yuji; Kanai, Riichiro; Kohyama, Tomoki; Idemitsu, Wataru; Maki, Yuichi; Igarashi, Takashi; Takahashi, Hiroyuki; Kanno, Hiroshi; Yamada, Yasuhiko

    2016-06-01

    It is essential to assure the efficacy of antimicrobials at the initial phase of therapy. However, increasing the volume of distribution (Vd) of hydrophilic antimicrobials in critically ill patients leads to reduced antimicrobial concentration in plasma and tissue, which may adversely affect the efficacy of that therapy. The aim of the present study was to establish a theoretical methodology for setting an appropriate level for initial vancomycin therapy in individual patients based on Acute Physiology and Chronic Health Evaluation (APACHE) II score. We obtained data from patients who received intravenous vancomycin for a suspected or definitively diagnosed Gram-positive bacterial infection within 72 h after admission to the intensive care unit. The Vd and elimination half-life (t 1/2) of vancomycin values were calculated using the Bayesian method, and we investigated the relationship between them and APACHE II score. There were significant correlations between APACHE II scores and Vd/actual body weight (ABW), as well as t 1/2 (r = 0.58, p < 0.05 and r = 0.74, p < 0.01, respectively). Our results suggested that the Vd and t 1/2 of vancomycin could be estimated using the following regression equations using APACHE II score.[Formula: see text] [Formula: see text]We found that APACHE II score was a useful index for predicting the Vd and t 1/2 of vancomycin, and used that to establish an initial vancomycin dosing regimen comprised of initial dose and administration interval for individual patients.

  12. Multiphasic growth curve analysis.

    NARCIS (Netherlands)

    Koops, W.J.

    1986-01-01

    Application of a multiphasic growth curve is demonstrated with 4 data sets, adopted from literature. The growth curve used is a summation of n logistic growth functions. Human height growth curves of this type are known as "double logistic" (n = 2) and "triple logistic" (n = 3) growth curves (Bock

  13. Multiphasic analysis of growth.

    NARCIS (Netherlands)

    Koops, W.J.

    1989-01-01

    The central theme of this thesis is the mathematical analysis of growth in animals, based on the theory of multiphasic growth. Growth in biological terms is related to increase in size and shape. This increase is determined by internal (genetical) and external (environmental) factors. Well known mat

  14. Differences in pharmacokinetics and pharmacodynamics of colistimethate sodium (CMS) and colistin between three different CMS dosage regimens in a critically ill patient infected by a multidrug-resistant Acinetobacter baumannii.

    Science.gov (United States)

    Luque, Sònia; Grau, Santiago; Valle, Marta; Sorlí, Luisa; Horcajada, Juan Pablo; Segura, Concha; Alvarez-Lerma, Francisco

    2013-08-01

    Use of colistin has re-emerged for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria, but information on its pharmacokinetics and pharmacodynamics is limited, especially in critically ill patients. Recent data from pharmacokinetic/pharmacodynamic (PK/PD) population studies have suggested that this population could benefit from administration of higher than standard doses of colistimethate sodium (CMS), but the relationship between administration of incremental doses of CMS and corresponding PK/PD parameters as well as its efficacy and toxicity have not yet been investigated in a clinical setting. The objective was to study the PK/PD differences of CMS and colistin between three different CMS dosage regimens in the same critically ill patient. A critically ill patient with nosocomial pneumonia caused by a MDR Acinetobacter baumannii received incremental doses of CMS. During administration of the different CMS dosage regimens, CMS and colistin plasma concentrations were determined and PK/PD indexes were calculated. With administration of the highest CMS dose once daily (720 mg every 24h), the peak plasma concentration of CMS and colistin increased to 40.51 mg/L and 1.81 mg/L, respectively, and the AUC0-24/MIC of colistin was 184.41. This dosage regimen was efficacious, and no nephrotoxicity or neurotoxicity was observed. In conclusion, a higher and extended-interval CMS dosage made it possible to increase the exposure of CMS and colistin in a critically ill patient infected by a MDR A. baumannii and allowed a clinical and microbiological optimal response to be achieved without evidence of toxicity.

  15. Multiphase permittivity imaging using absolute value electrical capacitance tomography data and a level set algorithm.

    Science.gov (United States)

    Al Hosani, E; Soleimani, M

    2016-06-28

    Multiphase flow imaging is a very challenging and critical topic in industrial process tomography. In this article, simulation and experimental results of reconstructing the permittivity profile of multiphase material from data collected in electrical capacitance tomography (ECT) are presented. A multiphase narrowband level set algorithm is developed to reconstruct the interfaces between three- or four-phase permittivity values. The level set algorithm is capable of imaging multiphase permittivity by using one set of ECT measurement data, so-called absolute value ECT reconstruction, and this is tested with high-contrast and low-contrast multiphase data. Simulation and experimental results showed the superiority of this algorithm over classical pixel-based image reconstruction methods. The multiphase level set algorithm and absolute ECT reconstruction are presented for the first time, to the best of our knowledge, in this paper and critically evaluated. This article is part of the themed issue 'Supersensing through industrial process tomography'. © 2016 The Author(s).

  16. Multiphase forces on bend structures

    NARCIS (Netherlands)

    Nennie, E.D.; Belfroid, S.P.C.

    2016-01-01

    Piping structures are generally subjected to high dynamic loading due to multiphase forces. In particular subsea structures are very vulnerable as large flexibility is required to cope for instance with thermal stresses. The forces due to multiphase flow are characterized by a broadband spectrum wit

  17. Multiphase forces on bend structures

    NARCIS (Netherlands)

    Nennie, E.D.; Belfroid, S.P.C.

    2016-01-01

    Piping structures are generally subjected to high dynamic loading due to multiphase forces. In particular subsea structures are very vulnerable as large flexibility is required to cope for instance with thermal stresses. The forces due to multiphase flow are characterized by a broadband spectrum wit

  18. Multiphase Flow Dynamics 1 Fundamentals

    CERN Document Server

    Kolev, Nikolay Ivanov

    2012-01-01

    Multi-phase flows are part of our natural environment such as tornadoes, typhoons, air and water pollution and volcanic activities as well as part of industrial technology such as power plants, combustion engines, propulsion systems, or chemical and biological industry. The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. In its fourth extended edition the successful monograph package “Multiphase Flow Dynmics” contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present first volume the local volume and time averaging is used to derive a complete set of conservation equations for three fluids each of them having multi components as constituents. Large parts of the book are devoted on the design of successful numerical methods for solving the...

  19. Multiphase flow dynamics 1 fundamentals

    CERN Document Server

    Kolev, Nikolay Ivanov

    2004-01-01

    Multi-phase flows are part of our natural environment such as tornadoes, typhoons, air and water pollution and volcanic activities as well as part of industrial technology such as power plants, combustion engines, propulsion systems, or chemical and biological industry. The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. In its third extended edition this monograph contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present first volume the fundamentals of multiphase dynamics are provided. This third edition includes various updates, extensions and improvements in all book chapters.

  20. Multiphase flow dynamics 1 fundamentals

    CERN Document Server

    Kolev, Nikolay Ivanov

    2007-01-01

    Multi-phase flows are part of our natural environment such as tornadoes, typhoons, air and water pollution and volcanic activities as well as part of industrial technology such as power plants, combustion engines, propulsion systems, or chemical and biological industry. The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. In its third extended edition this monograph contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present first volume the fundamentals of multiphase dynamics are provided. This third edition includes various updates, extensions and improvements in all book chapters.

  1. Improving adherence to medical regimens for juvenile rheumatoid arthritis

    Directory of Open Access Journals (Sweden)

    Lindsley Carol B

    2007-05-01

    Full Text Available Abstract Poor adherence to medical regimens can compromise the efficacy of treatments for children and adolescents with juvenile rheumatoid arthritis (JRA. The purpose of this review is to describe medical regimens for the treatment of JRA and the rates of adherence to these regimens. We also summarize and critically the few research studies aimed at improving adherence to regimens for JRA. Finally, we summarize strategies for enhancing adherence in clinical practice.

  2. Classifying insulin regimens

    DEFF Research Database (Denmark)

    Neu, A; Lange, K; Barrett, T

    2015-01-01

    Modern insulin regimens for the treatment of type 1 diabetes are highly individualized. The concept of an individually tailored medicine accounts for a broad variety of different insulin regimens applied. Despite clear recommendations for insulin management in children and adolescents with type 1...... diabetes there is little distinctiveness about concepts and the nomenclature is confusing. Even among experts similar terms are used for different strategies. The aim of our review--based on the experiences of the Hvidoere Study Group (HSG)--is to propose comprehensive definitions for current insulin...... variety of insulin regimens applied in each center, respectively. Furthermore, the understanding of insulin regimens has been persistently different between the centers since more than 20 yr. Not even the terms 'conventional' and 'intensified therapy' were used consistently among all members. Besides...

  3. Multiphase flow dynamics 1 fundamentals

    CERN Document Server

    Kolev, Nikolay Ivanov

    2015-01-01

    In its fifth extended edition the successful monograph package “Multiphase Flow Dynamics” contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present first volume the local volume and time averaging is used to derive a complete set of conservation equations for three fluids each of them having multi components as constituents. Large parts of the book are devoted on the design of successful numerical methods for solving the obtained system of partial differential equations. Finally the analysis is repeated for boundary fitted curvilinear coordinate systems designing methods applicable for interconnected multi-blocks. This fifth edition includes various updates, extensions, improvements and corrections, as well as  a completely new chapter containing the basic physics describing the multi-phase flow in tu...

  4. Multiphase Flow Dynamics 2 Mechanical Interactions

    CERN Document Server

    Kolev, Nikolay Ivanov

    2012-01-01

    Multi-phase flows are part of our natural environment such as tornadoes, typhoons, air and water pollution and volcanic activities as well as part of industrial technology such as power plants, combustion engines, propulsion systems, or chemical and biological industry. The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. .In its fourth extended edition the successful monograph package “Multiphase Flow Daynmics” contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present second volume the methods for describing the mechanical interactions in multiphase dynamics are provided. This fourth edition includes various updates, extensions, improvements and corrections.   "The literature in the field of multiphase flows is numerous. Therefore, it i...

  5. Multiphase flows in confinement with complex geometries

    Science.gov (United States)

    Aymard, Benjamin; Pradas, Marc; Vaes, Urbain; Kalliadasis, Serafim

    2016-11-01

    Understanding the dynamics of immiscible fluids in confinement is crucial in numerous applications such as oil recovery, fuel cells and the rapidly growing field of microfluidics. Complexities such as microstructures, chemical-topographical heterogeneities or porous membranes, can often induce non-trivial effects such as critical phenomena and phase transitions . The dynamics of confined multiphase flows may be efficiently described using diffuse-interface theory, leading to the Cahn-Hilliard-Navier-Stokes(CHNS) equations with Cahn wetting boundary conditions. Here we outline an efficient numerical method to solve the CHNS equations using advanced geometry-capturing mesh techniques both in two and three dimensional scenarios. The methodology is applied to two different systems: a droplet on a spatially chemical-topographical heterogeneous substrateand a microfluidic separator.

  6. A Transformerless Medium Voltage Multiphase Motor Drive System

    Directory of Open Access Journals (Sweden)

    Dan Wang

    2016-04-01

    Full Text Available A multiphase motor has several major advantages, such as high reliability, fault tolerance, and high power density. It is a critical issue to develop a reliable and efficient multiphase motor drive system. In this paper, a transformerless voltage source converter-based drive system for a medium-voltage (MV multiphase motor is proposed. This drive converter employs cascaded H-bridge rectifiers loaded by H-bridge inverters as the interface between the grid and multiphase motor. The cascaded H-bridge rectifier technique makes the drive system able to be directly connected to the MV grid without the phase-shifting transformer because it can offset the voltage level gap between the MV grid and the semiconductor devices, provide near-sinusoidal AC terminal voltages without filters, and draw sinusoidal line current from the grid. Based on a digital signal processor (DSP, a complete improved Phase Disposition Pulse Width Modulation (PD-PWM method is developed to ensure the individual DC-link capacitor voltage balancing for enhancing the controllability and limiting the voltage and power stress on the H-bridge cells. A downscaled prototype is designed and developed based on a nine-phase motor. The experimental results verify the excellent performances of the proposed drive system and control strategy in steady-state and variant-frequency startup operations.

  7. Multi-Phase Modeling of Rainbird Water Injection

    Science.gov (United States)

    Vu, Bruce T.; Moss, Nicholas; Sampson, Zoe

    2014-01-01

    This paper describes the use of a Volume of Fluid (VOF) multiphase model to simulate the water injected from a rainbird nozzle used in the sound suppression system during launch. The simulations help determine the projectile motion for different water flow rates employed at the pad, as it is critical to know if water will splash on the first-stage rocket engine during liftoff.

  8. Numerical Solver for Multiphase Flows

    OpenAIRE

    Sousa, Victor C B; Scalo, Carlo

    2015-01-01

    The technological development of micro-scale electronic devices is bounded by the challenge of dissipating their heat output. Latent heat absorbed by a fluid during phase transition offers exceptional cooling capabilities while allowing for the design of compact heat exchangers. The understanding of heat transport dynamics in the context of multiphase flow physics is hampered by the limited access to detailed flow features offered by experimental measurements. Computational Fluid Dynamics (CF...

  9. Technical Report on NETL's Non Newtonian Multiphase Slurry Workshop: A path forward to understanding non-Newtonian multiphase slurry flows

    Energy Technology Data Exchange (ETDEWEB)

    Edited by Guenther, Chris; Garg, Rahul

    2013-08-19

    The Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) sponsored a workshop on non-Newtonian multiphase slurry at NETL’s Morgantown campus August 19 and 20, 2013. The objective of this special two-day meeting of 20-30 invited experts from industry, National Labs and academia was to identify and address technical issues associated with handling non-Newtonian multiphase slurries across various facilities managed by DOE. Particular emphasis during this workshop was placed on applications managed by the Office of Environmental Management (EM). The workshop was preceded by two webinars wherein personnel from ORP and NETL provided background information on the Hanford WTP project and discussed the critical design challenges facing this project. In non-Newtonian fluids, viscosity is not constant and exhibits a complex dependence on applied shear stress or deformation. Many applications under EM’s tank farm mission involve non-Newtonian slurries that are multiphase in nature; tank farm storage and handling, slurry transport, and mixing all involve multiphase flow dynamics, which require an improved understanding of the mechanisms responsible for rheological changes in non-Newtonian multiphase slurries (NNMS). To discuss the issues in predicting the behavior of NNMS, the workshop focused on two topic areas: (1) State-of-the-art in non-Newtonian Multiphase Slurry Flow, and (2) Scaling up with Confidence and Ensuring Safe and Reliable Long-Term Operation.

  10. Multiphase Flow Dynamics 3 Thermal Interactions

    CERN Document Server

    Kolev, Nikolay Ivanov

    2012-01-01

    Multi-phase flows are part of our natural environment such as tornadoes, typhoons, air and water pollution and volcanic activities as well as part of industrial technology such as power plants, combustion engines, propulsion systems, or chemical and biological industry. The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. .In its fourth extended edition the successful monograph package “Multiphase Flow Daynmics” contains theory, methods and practical experience for describing complex transient multi-phase processes in arbitrary geometrical configurations, providing a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics. In the present third volume methods for describing of the thermal interactions in multiphase dynamics are provided. In addition a large number of valuable experiments is collected and predicted using the methods introduced in this monograph. In this way the accuracy of the methods is reve...

  11. Proceedings of submicron multiphase materials

    Energy Technology Data Exchange (ETDEWEB)

    Baney, R.; Gilliom, L.; Hirano, S.I.; Schmidt, H.

    1992-01-01

    This book contains the papers presented at Symposium R of the spring 1992 Materials Research Society meeting held in San Francisco, California. The title of the symposium, Submicron Multiphase Materials, was selected by the organizers to encompass the realm of composite materials from those smaller than conventional fiber matrix composites to those with phase separation dimensions approaching molecular dimensions. The development of composite materials is as old as the development of materials. Humans quickly learned that, by combining materials, the best properties of each can be realized and that, in fact, synergistic effects often arise. For example, chopped straw was used by the Israelites to limit cracking in bricks. The famed Japanese samurai swords were multilayers of hard oxide and tough ductile materials. One also finds in nature examples of composite materials. These range form bone to wood, consisting of a hard phase which provides strength and stiffness and a softer phase for toughness. Advanced composites are generally thought of as those which are based on a high modulus, discontinuous, chopped or woven fiber phase and a continuous polymer phase. In multiphase composites, dimensions can range from meters in materials such as steel rod-reinforced concrete structures to angstroms. In macrophase separated composite materials, properties frequently follow the rule of mixtures with the properties approximating the arithmetic mean of the properties of each individual phase, if there is good coupling between the phases. As the phases become smaller, the surface to volume ratio grows in importance with respect to properties. Interfacial and interphase phenomena being to dominate. Surface free energies play an ever increasing role in controlling properties. In recent years, much research in materials science has been directed at multiphase systems where phase separations are submicron in at least some dimension.

  12. Problems of multiphase fluid filtration

    CERN Document Server

    Konovalov, AN

    1994-01-01

    This book deals with a spectrum of problems related to the mathematical modeling of multiphase filtration. Emphasis is placed on an inseparable triad: model - algorithm - computer code. An analysis of new and traditional filtration problems from the point of view of both their numerical implementation and the reproduction of one or another technological characteristics of the processes under consideration is given. The basic principles which underlie the construction of efficient numerical methods taking into account the filtration problems are discussed: non-evolutionary nature, degeneration,

  13. Germanium multiphase equation of state

    Science.gov (United States)

    Crockett, S. D.; De Lorenzi-Venneri, G.; Kress, J. D.; Rudin, S. P.

    2014-05-01

    A new SESAME multiphase germanium equation of state (EOS) has been developed utilizing the best available experimental data and density functional theory (DFT) calculations. The equilibrium EOS includes the Ge I (diamond), the Ge II (β-Sn) and the liquid phases. The foundation of the EOS is based on density functional theory calculations which are used to determine the cold curve and the Debye temperature. Results are compared to Hugoniot data through the solid-solid and solid-liquid transitions. We propose some experiments to better understand the dynamics of this element.

  14. Multiscale thermomechanical analysis of multiphase materials

    NARCIS (Netherlands)

    Yadegari Varnamkhasti, S.

    2015-01-01

    The thermomechanical simulation of materials with evolving, multiphase microstructures poses various modeling and numerical challenges. For example, the separate phases in a multiphase microstructure can interact with each other during thermal and/or mechanical loading, the effect of which is

  15. Multiphase porous media modelling: A novel approach to predicting food processing performance.

    Science.gov (United States)

    Khan, Md Imran H; Joardder, M U H; Kumar, Chandan; Karim, M A

    2016-07-20

    The development of a physics-based model of food processing is essential to improve the quality of processed food and optimize energy consumption. Food materials, particularly plant-based food materials, are complex in nature as they are porous and have hygroscopic properties. A multiphase porous media model for simultaneous heat and mass transfer can provide a realistic understanding of transport processes and thus can help to optimize energy consumption and improve food quality. Although the development of a multiphase porous media model for food processing is a challenging task because of its complexity, many researchers have attempted it. The primary aim of this paper is to present a comprehensive review of the multiphase models available in the literature for different methods of food processing, such as drying, frying, cooking, baking, heating, and roasting. A critical review of the parameters that should be considered for multiphase modelling is presented which includes input parameters, material properties, simulation techniques and the hypotheses. A discussion on the general trends in outcomes, such as moisture saturation, temperature profile, pressure variation, and evaporation patterns, is also presented. The paper concludes by considering key issues in the existing multiphase models and future directions for development of multiphase models.

  16. Frontiers and progress in multiphase flow

    CERN Document Server

    2014-01-01

    This volume presents state-of-the-art of reviews in the field of multiphase flow. In focusses on nonlinear aspects of multiphase flow networks as well as visualization experiments. The first chapter presents nonlinear aspects or deterministic chaos issues in the systems of multi-phase reactors.  The second chapter reviews two-phase flow dynamics in combination with complex network theory. The third chapter discusses evaporation mechanism in the wick of copper heat pipes. The last chapter investigates numerically the flow dynamics and heat and mass transfer in the laminar and turbulent boundary layer on the flat vertical plate.

  17. Multiphase lattice Boltzmann methods theory and application

    CERN Document Server

    Huang, Haibo; Lu, Xiyun

    2015-01-01

    Theory and Application of Multiphase Lattice Boltzmann Methods presents a comprehensive review of all popular multiphase Lattice Boltzmann Methods developed thus far and is aimed at researchers and practitioners within relevant Earth Science disciplines as well as Petroleum, Chemical, Mechanical and Geological Engineering. Clearly structured throughout, this book will be an invaluable reference  on the current state of all popular multiphase Lattice Boltzmann Methods (LBMs). The advantages and disadvantages of each model are presented in an accessible manner to enable the reader to choose the

  18. On multiphase negative flash for ideal solutions

    DEFF Research Database (Denmark)

    Yan, Wei; Stenby, Erling Halfdan

    2012-01-01

    coefficients. It is shown that this inner loop, named here as multiphase negative flash for ideal solutions, can be solved either by Michelsen's algorithm for multiphase normal flash, or by its variation which uses F−1 phase amounts as independent variables. In either case, the resulting algorithm is actually...... simpler than the corresponding normal flash algorithm. Unlike normal flash, multiphase negative flash for ideal solutions can diverge if the feasible domain for phase amounts is not closed. This can be judged readily during the iteration process. The algorithm can also be extended to the partial negative...

  19. Massively Parallel Direct Simulation of Multiphase Flow

    Energy Technology Data Exchange (ETDEWEB)

    COOK,BENJAMIN K.; PREECE,DALE S.; WILLIAMS,J.R.

    2000-08-10

    The authors understanding of multiphase physics and the associated predictive capability for multi-phase systems are severely limited by current continuum modeling methods and experimental approaches. This research will deliver an unprecedented modeling capability to directly simulate three-dimensional multi-phase systems at the particle-scale. The model solves the fully coupled equations of motion governing the fluid phase and the individual particles comprising the solid phase using a newly discovered, highly efficient coupled numerical method based on the discrete-element method and the Lattice-Boltzmann method. A massively parallel implementation will enable the solution of large, physically realistic systems.

  20. Reactive multiphase flow simulation workshop summary

    Energy Technology Data Exchange (ETDEWEB)

    VanderHeyden, W.B.

    1995-09-01

    A workshop on computer simulation of reactive multiphase flow was held on May 18 and 19, 1995 in the Computational Testbed for Industry at Los Alamos National Laboratory (LANL), Los Alamos, New Mexico. Approximately 35 to 40 people attended the workshop. This included 21 participants from 12 companies representing the petroleum, chemical, environmental and consumer products industries, two representatives from the DOE Office of Industrial Technologies and several from Los Alamos. The dialog at the meeting suggested that reactive multiphase flow simulation represents an excellent candidate for government/industry/academia collaborative research. A white paper on a potential consortium for reactive multiphase flow with input from workshop participants will be issued separately.

  1. Simulation of multiphase flow in hydrocyclone

    Directory of Open Access Journals (Sweden)

    Rudolf P.

    2013-04-01

    Full Text Available Multiphase gas-liquid-solid swirling flow within hydrocyclone is simulated. Geometry and boundary conditions are based on Hsieh's 75 mm hydrocyclone. Extensive simulations point that standard mixture model with careful selection of interphase drag law is suitable for correct prediction of particle classification in case of dilute suspensions. However this approach fails for higher mass loading. It is also confirmed that Reynolds stress model is the best choice for multiphase modeling of the swirling flow on relatively coarse grids.

  2. Simulation of multiphase flow in hydrocyclone

    Science.gov (United States)

    Rudolf, P.

    2013-04-01

    Multiphase gas-liquid-solid swirling flow within hydrocyclone is simulated. Geometry and boundary conditions are based on Hsieh's 75 mm hydrocyclone. Extensive simulations point that standard mixture model with careful selection of interphase drag law is suitable for correct prediction of particle classification in case of dilute suspensions. However this approach fails for higher mass loading. It is also confirmed that Reynolds stress model is the best choice for multiphase modeling of the swirling flow on relatively coarse grids.

  3. Simulation of multiphase flow in hydrocyclone

    OpenAIRE

    Rudolf P.

    2013-01-01

    Multiphase gas-liquid-solid swirling flow within hydrocyclone is simulated. Geometry and boundary conditions are based on Hsieh's 75 mm hydrocyclone. Extensive simulations point that standard mixture model with careful selection of interphase drag law is suitable for correct prediction of particle classification in case of dilute suspensions. However this approach fails for higher mass loading. It is also confirmed that Reynolds stress model is the best choice for multiphase modeling of the s...

  4. Metronomic chemotherapy regimens in oncology

    Directory of Open Access Journals (Sweden)

    M. Yu. Fedyanin

    2016-01-01

    Full Text Available Metronomic chemotherapy implies the regular use of cytotoxic agents in doses much smaller than the maximum tolerable doses for a long time. Preclinical experiments show that this treatment option has a many-sided (antiangiogenic, immunostimulating, and direct cytotoxic effect on tumor. Moreover, this approach has gained the widest acceptance in treating patients with metastatic breast cancer in clinical practice. By taking into account the high activity of angiogenesis in colon cancer progression, it is interesting to study the impact of metronomic chemotherapy regimens for this nosological entity as well. This literature review considers not only the history of metronomic chemotherapy, the mechanisms of action, and a range of drugs having an antitumor effect in the metronomic regimens, but also analyzes clinical trials of metronomic chemotherapy regimens in patients with metastatic colon cancer.

  5. Design of Multiphase Flow Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Urkedal, Hege

    1998-12-31

    This thesis proposes an experimental design procedure for multiphase experiments. The two-phase functions can be determined using data from a single experiment, while the three-phase relative permeabilities must be determined using data from multiple experiments. Various three-phase experimental designs have been investigated and the accuracy with which the flow functions may be determined using the corresponding data have been computed. Analytical sensitivity coefficients were developed from two-phase to three-phase flow. Sensitivity coefficients are the derivative of the model output with respect to the model parameters. They are obtained by a direct method that takes advantage of the fact that the model equations are solved using the Newton-Raphson method, and some of the results from this solution can be used directly when solving the sensitivity equation. Numerical derivatives are avoided, which improves accuracy. The thesis uses an inverse methodology for determination of two- and three-phase relative permeability and capillary pressure functions. The main work has been the development of analytical sensitivity coefficients for two-and three-phase flow. This technical contribution has improved the accuracy both in parameter estimation and accuracy assessment of the estimates and reduced the computer time requirements. The proposed experimental design is also dependent on accurate sensitivity coefficients to give the right guidelines for how two- and three-phase experiments should be conducted. Following the proposed experimental design, three-phase relative permeability and capillary pressure functions have been estimated when multiple sets of experimental data have been reconciled by simulations. 74 refs., 69 figs., 18 tabs.

  6. Radiation damage in multiphase ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Men, Danju [Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697-2575 (United States); Patel, Maulik K.; Usov, Igor O. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Toiammou, Moidi; Monnet, Isabelle [CIMAP, CEA/CNRS/ENSICAEN/Universite de Caen-Basse Normandie, Bd Henri Becquerel, BP 5133, F-14070 Caen Cedex 5 (France); Pivin, Jean Claude [Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, CNRS-IN2P3-Universite Paris Sud, UMR 8609, Bat. 108, 91405 Orsay (France); Porter, John R. [Materials Department, University of California, Santa Barbara, CA 93106-5050 (United States); Mecartney, Martha L., E-mail: martham@uci.edu [Department of Chemical Engineering and Materials Science, University of California, Irvine, CA 92697-2575 (United States)

    2013-11-15

    Graphical abstract: Display Omitted -- Abstract: Four-phase ceramic composites containing 3 mol% Y{sub 2}O{sub 3} stabilized ZrO{sub 2} (3Y-TZP), Al{sub 2}O{sub 3}, MgAl{sub 2}O{sub 4}, and LaPO{sub 4} were synthesized as model materials representing inert matrix fuel with enhanced thermal conductivity and decreased radiation-induced microstructural damage with respect to single-phase UO{sub 2}. This multi-phase concept, if successful, could be applied to design advanced nuclear fuels which could then be irradiated to higher burn-ups. 3Y-TZP in the composite represents a host (fuel) phase with the lowest thermal conductivity and Al{sub 2}O{sub 3} is the high thermal conductivity phase. The role of MgAl{sub 2}O{sub 4} and LaPO{sub 4} was to stabilize the structure under irradiation. The radiation response was evaluated by ion irradiation at 500 °C with 10 MeV Au ions and at 800 °C with 92 MeV Xe ions, to simulate damage due to primary knock-on atoms and fission fragments, respectively. Radiation damage and microstructural changes were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy and computational modeling. Al{sub 2}O{sub 3}, Y{sub 2}O{sub 3} stabilized ZrO{sub 2} and MgAl{sub 2}O{sub 4} phases exhibit high amorphization resistance and remain stable when irradiated with both Au and Xe ions. A monoclinic-to-tetragonal phase transformation, however, is promoted by Xe and Au ion irradiation in 3Y-TZP. The LaPO{sub 4} monazite phase appears to melt, dewet the other phases, and recrystallize under Au irradiation, but does not change under Xe irradiation.

  7. Multiphase Systems for Medical Image Region Classification

    Science.gov (United States)

    Garamendi, J. F.; Malpica, N.; Schiavi, E.

    2009-05-01

    Variational methods for region classification have shown very promising results in medical image analysis. The Chan-Vese model is one of the most popular methods, but its numerical resolution is slow and it has serious drawbacks for most multiphase applications. In this work, we extend the link, stablished by Chambolle, between the two classes binary Chan-Vese model and the Rudin-Osher-Fatemi (ROF) model to a multiphase four classes minimal partition problem. We solve the ROF image restoration model and then we threshold the image by means of a genetic algorithm. This strategy allows for a more efficient algorithm due to the fact that only one well posed elliptic problem is solved instead of solving the coupled parabolic equations arising in the original multiphase Chan-Vese model.

  8. Multiphase reacting flows modelling and simulation

    CERN Document Server

    Marchisio, Daniele L

    2007-01-01

    The papers in this book describe the most widely applicable modeling approaches and are organized in six groups covering from fundamentals to relevant applications. In the first part, some fundamentals of multiphase turbulent reacting flows are covered. In particular the introduction focuses on basic notions of turbulence theory in single-phase and multi-phase systems as well as on the interaction between turbulence and chemistry. In the second part, models for the physical and chemical processes involved are discussed. Among other things, particular emphasis is given to turbulence modeling strategies for multiphase flows based on the kinetic theory for granular flows. Next, the different numerical methods based on Lagrangian and/or Eulerian schemes are presented. In particular the most popular numerical approaches of computational fluid dynamics codes are described (i.e., Direct Numerical Simulation, Large Eddy Simulation, and Reynolds-Averaged Navier-Stokes approach). The book will cover particle-based meth...

  9. Twin screw subsurface and surface multiphase pumps

    Energy Technology Data Exchange (ETDEWEB)

    Dass, P. [CAN-K GROUP OF COMPANIES, Edmonton, Alberta (Canada)

    2011-07-01

    A new subsurface twin screw multiphase pump has been developed to replace ESP and other artificial lift technologies. This technology has been under development for a few years, has been field tested and is now going for commercial applications. The subsurface twin screw technology consists of a pair of screws that do not touch and can be run with a top drive or submersible motor; and it carries a lot of benefits. This technology is easy to install and its low slippage makes it highly efficient with heavy oil. In addition twin screw multiphase pumps are capable of handling high viscosity fluids and thus their utilization can save water when used in thermal applications. It also induces savings of chemicals because asphaltenes do not break down easily as well as a reduction in SOR. The subsurface twin screw multiphase pump presented herein is an advanced technology which could be used in thermal applications.

  10. Multiphase flow dynamics 2 thermal and mechanical interactions

    CERN Document Server

    Kolev, Nikolay I

    2007-01-01

    The industrial use of multi-phase systems requires analytical and numerical strategies for predicting their behavior. This book contains theory, methods and practical experience for describing complex transient multi-phase processes. It provides a systematic presentation of the theory and practice of numerical multi-phase fluid dynamics.

  11. Direct numerical simulation of incompressible multiphase flow with phase change

    Science.gov (United States)

    Lee, Moon Soo; Riaz, Amir; Aute, Vikrant

    2017-09-01

    Simulation of multiphase flow with phase change is challenging because of the potential for unphysical pressure oscillations, spurious velocity fields and mass flux errors across the interface. The resulting numerical errors may become critical when large density contrasts are present. To address these issues, we present a new approach for multiphase flow with phase change that features, (i) a smooth distribution of sharp velocity jumps and mass flux within a narrow region surrounding the interface, (ii) improved mass flux projection from the implicit interface onto the uniform Cartesian grid and (iii) post-advection velocity correction step to ensure accurate velocity divergence in interfacial cells. These new features are implemented in combination with a sharp treatment of the jumps in pressure and temperature gradient. A series of 1-D, 2-D, axisymmetric and 3-D problems are solved to verify the improvements afforded by the new approach. Axisymmetric film boiling results are also presented, which show good qualitative agreement with heat transfer correlations as well as experimental observations of bubble shapes.

  12. Intrusive Method for Uncertainty Quantification in a Multiphase Flow Solver

    Science.gov (United States)

    Turnquist, Brian; Owkes, Mark

    2016-11-01

    Uncertainty quantification (UQ) is a necessary, interesting, and often neglected aspect of fluid flow simulations. To determine the significance of uncertain initial and boundary conditions, a multiphase flow solver is being created which extends a single phase, intrusive, polynomial chaos scheme into multiphase flows. Reliably estimating the impact of input uncertainty on design criteria can help identify and minimize unwanted variability in critical areas, and has the potential to help advance knowledge in atomizing jets, jet engines, pharmaceuticals, and food processing. Use of an intrusive polynomial chaos method has been shown to significantly reduce computational cost over non-intrusive collocation methods such as Monte-Carlo. This method requires transforming the model equations into a weak form through substitution of stochastic (random) variables. Ultimately, the model deploys a stochastic Navier Stokes equation, a stochastic conservative level set approach including reinitialization, as well as stochastic normals and curvature. By implementing these approaches together in one framework, basic problems may be investigated which shed light on model expansion, uncertainty theory, and fluid flow in general. NSF Grant Number 1511325.

  13. Multiphase Nanocrystalline Ceramic Concept for Nuclear Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Mecartnery, Martha [Univ. of California, Irvine, CA (United States); Graeve, Olivia [Univ. of California, San Diego, CA (United States); Patel, Maulik [Univ. of Liverpool (United Kingdom)

    2017-05-25

    The goal of this research is to help develop new fuels for higher efficiency, longer lifetimes (higher burn-up) and increased accident tolerance in future nuclear reactors. Multiphase nanocrystalline ceramics will be used in the design of simulated advanced inert matrix nuclear fuel to provide for enhanced plasticity, better radiation tolerance, and improved thermal conductivity

  14. Periodical multiphasic screening and lung cancer prevention.

    Science.gov (United States)

    Carel, R S

    1998-06-01

    The purpose of this work is to evaluate the utilization of information gathered by multiphasic screening with respect to lung cancer detection and smoking cessation techniques. A cohort (follow-up) study is reported in which cancer incidence and factors affecting its occurrence are evaluated in a group of about 20,000 presumably healthy adults along a period of approximately 10 years following comprehensive multiphasic health examinations. Lung cancer occurrence is primarily related to smoking. The risk is higher in smokers and is dose-dependent; OR = 0.21, (CI = 0.08, .53) in never smokers, OR = 1.53 (CI = 0.8, 3.2) in past and current moderate smokers, OR = 4.92 (CI = 2.18, 11.11) in current heavy smokers. Moreover, smokers with compromised pulmonary function (FEVI/FVC periodical multiphasic health examinations could be utilized by health professionals to encourage smoking cessation and smoking prevention in the appropriate screenees. Various elements of the multiphasic test results could contribute to such prevention efforts. While every smoker should receive appropriate evaluation and consultation regarding nicotine dependence, smokers with reduced pulmonary function represent an extra high risk group to which special attention should be given.

  15. Multiphase flow in porous media using CFD

    DEFF Research Database (Denmark)

    Hemmingsen, Casper Schytte; Walther, Jens Honore

    We present results from a new Navier-Stokes model for multiphase flow in porous media implemented in Ansys Fluent 16.2 [1]. The model includes the Darcy-Forchheimer source terms in the momentum equations and proper account for relative permeability and capillary pressure in the porous media...... to model both the non-porous and porous media using the same formulation....

  16. Multiphase Instabilities in Explosive Dispersal of Particles

    Science.gov (United States)

    Rollin, Bertrand; Ouellet, Frederick; Annamalai, Subramanian; Balachandar, S. ``Bala''

    2015-11-01

    Explosive dispersal of particles is a complex multiphase phenomenon that can be observed in volcanic eruptions or in engineering applications such as multiphase explosives. As the layer of particles moves outward at high speed, it undergoes complex interactions with the blast-wave structure following the reaction of the energetic material. Particularly in this work, we are interested in the multiphase flow instabilities related to Richmyer-Meshkov (RM) and Rayleigh-Taylor (RM) instabilities (in the gas phase and particulate phase), which take place as the particle layer disperses. These types of instabilities are known to depend on initial conditions for a relatively long time of their evolution. Using a Eulerian-Lagrangian approach, we study the growth of these instabilities and their dependence on initial conditions related to the particulate phase - namely, (i) particle size, (ii) initial distribution, and (iii) mass ratio (particles to explosive). Additional complexities associated with compaction of the layer of particles are avoided here by limiting the simulations to modest initial volume fraction of particles. A detailed analysis of the initial conditions and its effects on multiphase RM/RT-like instabilities in the context of an explosive dispersal of particles is presented. This work was supported by the U.S. Department of Energy, National Nuclear Security Administration, Advanced Simulation and Computing Program, as a Cooperative Agreement under the Predictive Science Academic Alliance Program, Contract No. DE-NA0002378.

  17. Some Specific CASL Requirements for Advanced Multiphase Flow Simulation of Light Water Reactors

    Energy Technology Data Exchange (ETDEWEB)

    R. A. Berry

    2010-11-01

    Because of the diversity of physical phenomena occuring in boiling, flashing, and bubble collapse, and of the length and time scales of LWR systems, it is imperative that the models have the following features: • Both vapor and liquid phases (and noncondensible phases, if present) must be treated as compressible. • Models must be mathematically and numerically well-posed. • The models methodology must be multi-scale. A fundamental derivation of the multiphase governing equation system, that should be used as a basis for advanced multiphase modeling in LWR coolant systems, is given in the Appendix using the ensemble averaging method. The remainder of this work focuses specifically on the compressible, well-posed, and multi-scale requirements of advanced simulation methods for these LWR coolant systems, because without these are the most fundamental aspects, without which widespread advancement cannot be claimed. Because of the expense of developing multiple special-purpose codes and the inherent inability to couple information from the multiple, separate length- and time-scales, efforts within CASL should be focused toward development of a multi-scale approaches to solve those multiphase flow problems relevant to LWR design and safety analysis. Efforts should be aimed at developing well-designed unified physical/mathematical and high-resolution numerical models for compressible, all-speed multiphase flows spanning: (1) Well-posed general mixture level (true multiphase) models for fast transient situations and safety analysis, (2) DNS (Direct Numerical Simulation)-like models to resolve interface level phenmena like flashing and boiling flows, and critical heat flux determination (necessarily including conjugate heat transfer), and (3) Multi-scale methods to resolve both (1) and (2) automatically, depending upon specified mesh resolution, and to couple different flow models (single-phase, multiphase with several velocities and pressures, multiphase with single

  18. Application and Perspectives of Multiphase Induction Motors

    Directory of Open Access Journals (Sweden)

    Benas Kundrotas

    2012-04-01

    Full Text Available The article considers the areas of applying multiphase induction motors. Their advantages against three phase motors have become the main reason for employing them in multiphase drives. The paper deals with the six-phase induction motor having two similar three phase windings in the stator shifted by 30 degrees in space and three phase windings in the rotor. Differential equations for this motor are presented and transformed to dq synchronous reference frame. The transformed equations are expressed in a matrix form and solved by MATLAB software using the Dormand-Prince (ode45 method. The transient characteristics of the torque, speed and current of the six-phase induction motor are calculated and discussed.Article in Lithuanian

  19. Error handling strategies in multiphase inverse modeling

    Energy Technology Data Exchange (ETDEWEB)

    Finsterle, S.; Zhang, Y.

    2010-12-01

    Parameter estimation by inverse modeling involves the repeated evaluation of a function of residuals. These residuals represent both errors in the model and errors in the data. In practical applications of inverse modeling of multiphase flow and transport, the error structure of the final residuals often significantly deviates from the statistical assumptions that underlie standard maximum likelihood estimation using the least-squares method. Large random or systematic errors are likely to lead to convergence problems, biased parameter estimates, misleading uncertainty measures, or poor predictive capabilities of the calibrated model. The multiphase inverse modeling code iTOUGH2 supports strategies that identify and mitigate the impact of systematic or non-normal error structures. We discuss these approaches and provide an overview of the error handling features implemented in iTOUGH2.

  20. Variational continuum multiphase poroelasticity theory and applications

    CERN Document Server

    Serpieri, Roberto

    2017-01-01

    This book collects the theoretical derivation of a recently presented general variational macroscopic continuum theory of multiphase poroelasticity (VMTPM), together with its applications to consolidation and stress partitioning problems of interest in several applicative engineering contexts, such as in geomechanics and biomechanics. The theory is derived based on a purely-variational deduction, rooted in the least-Action principle, by considering a minimal set of kinematic descriptors. The treatment herein considered keeps a specific focus on the derivation of most general medium-independent governing equations. It is shown that VMTPM recovers paradigms of consolidated use in multiphase poroelasticity such as Terzaghi's stress partitioning principle and Biot's equations for wave propagation. In particular, the variational treatment permits the derivation of a general medium-independent stress partitioning law, and the proposed variational theory predicts that the external stress, the fluid pressure, and the...

  1. Modeling variability in porescale multiphase flow experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Bowen; Bao, Jie; Oostrom, Mart; Battiato, Ilenia; Tartakovsky, Alexandre M.

    2017-07-01

    Microfluidic devices and porescale numerical models are commonly used to study multiphase flow in biological, geological, and engineered porous materials. In this work, we perform a set of drainage and imbibition experiments in six identical microfluidic cells to study the reproducibility of multiphase flow experiments. We observe significant variations in the experimental results, which are smaller during the drainage stage and larger during the imbibition stage. We demonstrate that these variations are due to sub-porescale geometry differences in microcells (because of manufacturing defects) and variations in the boundary condition (i.e.,fluctuations in the injection rate inherent to syringe pumps). Computational simulations are conducted using commercial software STAR-CCM+, both with constant and randomly varying injection rate. Stochastic simulations are able to capture variability in the experiments associated with the varying pump injection rate.

  2. Online recognition of the multiphase flow regime

    Institute of Scientific and Technical Information of China (English)

    BAI BoFeng; ZHANG ShaoJun; ZHAO Liang; ZHANG XiMin; GUO LieJin

    2008-01-01

    The key reasons that the present method cannot be used to solve the industrial multi-phase flow pattern recognition are clarified firstly. The prerequisite to realize the online recognition is proposed and recognition rules for partial flow pattern are obtained based on the massive experimental data. The standard templates for every flow regime feature are calculated with self-organization cluster algorithm. The multi-sensor data fusion method is proposed to realize the online recognition of multiphase flow regime with the pressure and differential pressure signals, which overcomes the severe influence of fluid flow velocity and the oil fraction on the recognition. The online recognition method is tested in the practice, which has less than 10 percent measurement error. The method takes advantages of high confidence, good fault tolerance and less requirement of single sensor performance.

  3. Modeling variability in porescale multiphase flow experiments

    Science.gov (United States)

    Ling, Bowen; Bao, Jie; Oostrom, Mart; Battiato, Ilenia; Tartakovsky, Alexandre M.

    2017-07-01

    Microfluidic devices and porescale numerical models are commonly used to study multiphase flow in biological, geological, and engineered porous materials. In this work, we perform a set of drainage and imbibition experiments in six identical microfluidic cells to study the reproducibility of multiphase flow experiments. We observe significant variations in the experimental results, which are smaller during the drainage stage and larger during the imbibition stage. We demonstrate that these variations are due to sub-porescale geometry differences in microcells (because of manufacturing defects) and variations in the boundary condition (i.e., fluctuations in the injection rate inherent to syringe pumps). Computational simulations are conducted using commercial software STAR-CCM+, both with constant and randomly varying injection rates. Stochastic simulations are able to capture variability in the experiments associated with the varying pump injection rate.

  4. Non-Equilibrium Thermodynamics in Multiphase Flows

    CERN Document Server

    Mauri, Roberto

    2013-01-01

    Non-equilibrium thermodynamics is a general framework that allows the macroscopic description of irreversible processes. This book introduces non-equilibrium thermodynamics and its applications to the rheology of multiphase flows. The subject is relevant to graduate students in chemical and mechanical engineering, physics and material science. This book is divided into two parts. The first part presents the theory of non-equilibrium thermodynamics, reviewing its essential features and showing, when possible, some applications. The second part of this book deals with how the general theory can be applied to model multiphase flows and, in particular, how to determine their constitutive relations. Each chapter contains problems at the end, the solutions of which are given at the end of the book. No prior knowledge of statistical mechanics is required; the necessary prerequisites are elements of transport phenomena and on thermodynamics. “The style of the book is mathematical, but nonetheless it remains very re...

  5. Multiphase Transformer Modelling using Finite Element Method

    Directory of Open Access Journals (Sweden)

    Nor Azizah Mohd Yusoff

    2015-03-01

    Full Text Available In the year of 1970 saw the starting invention of the five-phase motor as the milestone in advanced electric motor. Through the years, there are many researchers, which passionately worked towards developing for multiphase drive system. They developed a static transformation system to obtain a multiphase supply from the available three-phase supply. This idea gives an influence for further development in electric machines as an example; an efficient solution for bulk power transfer. This paper highlighted the detail descriptions that lead to five-phase supply with fixed voltage and frequency by using Finite-Element Method (FEM. Identifying of specification on a real transformer had been done before applied into software modeling. Therefore, Finite-Element Method provides clearly understandable in terms of visualize the geometry modeling, connection scheme and output waveform.

  6. Modified Invasion Percolation Models for Multiphase Processes

    Energy Technology Data Exchange (ETDEWEB)

    Karpyn, Zuleima [Pennsylvania State Univ., State College, PA (United States)

    2015-01-31

    This project extends current understanding and modeling capabilities of pore-scale multiphase flow physics in porous media. High-resolution X-ray computed tomography imaging experiments are used to investigate structural and surface properties of the medium that influence immiscible displacement. Using experimental and computational tools, we investigate the impact of wetting characteristics, as well as radial and axial loading conditions, on the development of percolation pathways, residual phase trapping and fluid-fluid interfacial areas.

  7. Multiphase fluid hammer: modeling, experiments and simulations

    OpenAIRE

    Lema Rodríguez, Marcos

    2013-01-01

    This thesis deals with the experimental and numerical analysis of the water hammer phenomenon generated by the discharge of a pressurized liquid into a pipeline kept under vacuum conditions. This flow configuration induces several multiphase phenomena such as cavitation and gas desorption that cannot be ignored in the water hammer behavior.The motivation of this research work comes from the liquid propulsion systems used in spacecrafts, which can undergo fluid hammer effects threatening the s...

  8. NMR studies of multiphase flows II

    Energy Technology Data Exchange (ETDEWEB)

    Altobelli, S.A.; Caprihan, A.; Fukushima, E. [Lovelace Institutes, Albuquerque, NM (United States)] [and others

    1995-12-31

    NMR techniques for measurements of spatial distribution of material phase, velocity and velocity fluctuation are being developed and refined. Versions of these techniques which provide time average liquid fraction and fluid phase velocity have been applied to several concentrated suspension systems which will not be discussed extensively here. Technical developments required to further extend the use of NMR to the multi-phase flow arena and to provide measurements of previously unobtainable parameters are the focus of this report.

  9. Measurement strategies for downhole multiphase metering

    Energy Technology Data Exchange (ETDEWEB)

    Hammer, Erling A.; Johansen, Geir Anton; Tollefsen, Jarle; Aabro, Eirik [Bergen Univ.(Norway)

    1997-07-01

    There will be an increasing demand for multiphase subsea and downhole meters in the future. Both at the sea bottom and downhole the flow regimes in the production pipes or in the manifolds at the templates, may differ from the ideal homogeneous mixture. Further, in line mixers should be avoided to reduce pressure drops and maintenance costs. The next generation multiphase meters will therefore call for flow regime independent and non-intrusive sensor systems. Since all sensor principles used in multiphase flowmeters today are highly dependent on the distribution of the components in the mixture, and thus make the measurement range limited, multi-sensor principles may be the solution to obtain better accuracy for larger ranges of component fractions and applications. Both the capacitance-, conductance-, microwave- and gamma-principles can be used in multi-sensor arrangement to provide cross-sectional information about the component distribution. Hence, the meter can be used at all types of flow regimes and at any position without mixers or separators. (author)

  10. Cultural Validity of the Minnesota Multiphasic Personality Inventory-2 Empirical Correlates: Is This the Best We Can Do?

    Science.gov (United States)

    Hill, Jill S.; Robbins, Rockey R.; Pace, Terry M.

    2012-01-01

    This article critically reviews empirical correlates of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989), based on several validation studies conducted with different racial, ethnic, and cultural groups. A major critique of the reviewed MMPI-2 studies was focused on the use of…

  11. Sedation regimens for gastrointestinal endoscopy.

    Science.gov (United States)

    Moon, Sung-Hoon

    2014-03-01

    Sedation allows patients to tolerate unpleasant endoscopic procedures by relieving anxiety, discomfort, or pain. It also reduces a patient's risk of physical injury during endoscopic procedures, while providing the endoscopist with an adequate setting for a detailed examination. Sedation is therefore considered by many endoscopists to be an essential component of gastrointestinal endoscopy. Endoscopic sedation by nonanesthesiologists is a worldwide practice and has been proven effective and safe. Moderate sedation/analgesia is generally accepted as an appropriate target for sedation by nonanesthesiologists. This focused review describes the general principles of endoscopic sedation, the detailed pharmacology of sedatives and analgesics (focused on midazolam, propofol, meperidine, and fentanyl), and the multiple regimens available for use in actual practice.

  12. On the Grand Challenges in Physical Petrology: the Multiphase Crossroads

    Science.gov (United States)

    Bergantz, G. W.

    2014-12-01

    Rapid progress in experimental, micro-analytical and textural analysis at the crystal scale has produced an unprecedented record of magmatic processes. However an obstacle to further progress is the lack of understanding of how mass, energy and momentum flux associated with crystal-rich, open-system events produces identifiable outcomes. Hence developing a physically-based understanding of magmatic systems linking micro-scale petrological observations with a physical template operating at the macro-scale presents a so-called "Grand Challenge." The essence of this challenge is that magmatic systems have characteristic length and feedback scales between those accessible by classical continuum and discrete methods. It has become increasingly obvious that the old-school continuum methods have limited resolution and power of explanation for multiphase (real) magma dynamics. This is, in part, because in crystal-rich systems the deformation is non-affine, and so the concept of constitutive behavior is less applicable and likely not even relevant, especially if one is interested in the emergent character of micro-scale processes. One expression of this is the cottage industry of proposing viscosity laws for magmas, which serves as "blunt force" de facto corrections for what is intrinsically multiphase behavior. Even in more fluid-rich systems many of these laws are not suitable for use in the very transport theories they aim to support. The alternative approach is the discrete method, where multiphase interactions are explicitly resolved. This is a daunting prospect given the numbers of crystals in magmas. But perhaps all crystals don't need to be modeled. I will demonstrate how discrete methods can recover critical state behavior, resolve crystal migration, the onset of visco-elastic behavior such as melt-present shear bands which sets the large-scale mixing volumes, some of the general morpho-dynamics that underlies purported rheological models, and transient controls on

  13. Multiphase Flow Technology Impacts on Thermal Control Systems for Exploration

    Science.gov (United States)

    McQuillen, John; Sankovic, John; Lekan, Jack

    2006-01-01

    The Two-Phase Flow Facility (TPHIFFy) Project focused on bridging the critical knowledge gap by developing and demonstrating critical multiphase fluid products for advanced life support, thermal management and power conversion systems that are required to enable the Vision for Space Exploration. Safety and reliability of future systems will be enhanced by addressing critical microgravity fluid physics issues associated with flow boiling, condensation, phase separation, and system stability. The project included concept development, normal gravity testing, and reduced gravity aircraft flight campaigns, in preparation for the development of a space flight experiment implementation. Data will be utilized to develop predictive models that could be used for system design and operation. A single fluid, two-phase closed thermodynamic loop test bed was designed, assembled and tested. The major components in this test bed include: a boiler, a condenser, a phase separator and a circulating pump. The test loop was instrumented with flow meters, thermocouples, pressure transducers and both high speed and normal speed video cameras. A low boiling point surrogate fluid, FC-72, was selected based on scaling analyses using preliminary designs for operational systems. Preliminary results are presented which include flow regime transitions and some observations regarding system stability.

  14. A Course in Transport Phenomena in Multicomponent, Multiphase, Reacting Systems.

    Science.gov (United States)

    Carbonell, R. G.; Whitaker, S.

    1978-01-01

    This course concentrates on a rigorous development of the multicomponent transport equations, boundary conditions at phase interfaces, and volume-averaged transport equations for multiphase reacting systems. (BB)

  15. Numerical Simulation of the Multiphase Flow in the Rheinsahl-Heraeus (RH) System

    Science.gov (United States)

    Geng, Dian-Qiao; Lei, Hong; He, Ji-Cheng

    2010-02-01

    Knowledge of gas-liquid multiphase flow behavior in the Rheinsahl-Heraeus (RH) system is of great significance to clarify the circulation flow rate, decarburization, and inclusion removal with a reliable description. Thus, based on the separate model of injecting gas behavior, a novel mathematical model of multiphase flow has been developed to give the distribution of gas holdup in the RH system. The numerical results show that the predicted circulation flow rates, the predicted flow velocities, and the predicted mixing times agree with the measured results in a water model and that the predicted tracer concentration curve agrees with the results obtained in an actual RH system. With a lower lifting gas flow rate, the rising gas bubbles are concentrated near the wall; with a higher lifting gas flow rate, gas bubbles can reach the center of the up-snorkel. A critical lifting gas flow rate is used to obtain the maximum circulation flow rate.

  16. Aggressive regimens for multidrug-resistant tuberculosis reduce recurrence.

    Science.gov (United States)

    Franke, Molly F; Appleton, Sasha C; Mitnick, Carole D; Furin, Jennifer J; Bayona, Jaime; Chalco, Katiuska; Shin, Sonya; Murray, Megan; Becerra, Mercedes C

    2013-03-01

    Recurrent tuberculosis disease occurs within 2 years in as few as 1% and as many as 29% of individuals successfully treated for multidrug-resistant (MDR) tuberculosis. A better understanding of treatment-related factors associated with an elevated risk of recurrent tuberculosis after cure is urgently needed to optimize MDR tuberculosis therapy. We conducted a retrospective cohort study among adults successfully treated for MDR tuberculosis in Peru. We used multivariable Cox proportional hazards regression analysis to examine whether receipt of an aggressive MDR tuberculosis regimen for ≥18 months following sputum conversion from positive to negative was associated with a reduced rate of recurrent tuberculosis. Among 402 patients, the median duration of follow-up was 40.5 months (interquartile range, 21.2-53.4). Receipt of an aggressive MDR tuberculosis regimen for ≥18 months following sputum conversion was associated with a lower risk of recurrent tuberculosis (hazard ratio, 0.40 [95% confidence interval, 0.17-0.96]; P = .04). A baseline diagnosis of diabetes mellitus also predicted recurrent tuberculosis (hazard ratio, 10.47 [95% confidence interval, 2.17-50.60]; P = .004). Individuals who received an aggressive MDR tuberculosis regimen for ≥18 months following sputum conversion experienced a lower rate of recurrence after cure. Efforts to ensure that an aggressive regimen is accessible to all patients with MDR tuberculosis, such as minimization of sequential ineffective regimens, expanded drug access, and development of new MDR tuberculosis compounds, are critical to reducing tuberculosis recurrence in this population. Patients with diabetes mellitus should be carefully managed during initial treatment and followed closely for recurrent disease.

  17. Axisymmetric multiphase lattice Boltzmann method for generic equations of state

    NARCIS (Netherlands)

    Reijers, Sten Arjen; Gelderblom, Hanneke; Toschi, F.

    2016-01-01

    We present an axisymmetric lattice Boltzmann model based on the Kupershtokh et al. multiphase model that is capable of solving liquid–gas density ratios up to 103. Appropriate source terms are added to the lattice Boltzmann evolution equation to fully recover the axisymmetric multiphase conservation

  18. Industrial applications of multi-functional, multi-phase reactors

    NARCIS (Netherlands)

    Harmsen, G.J.; Chewter, L.A.

    1999-01-01

    To reveal trends in the design and operation of multi-functional, multi-phase reactors, this paper describes, in historical sequence, three industrial applications of multi-functional, multi-phase reactors developed and operated by Shell Chemicals during the last five decades. For each case, we desc

  19. Soft-sensing, non-intrusive multiphase flow meter

    NARCIS (Netherlands)

    Wrobel, K.; Schiferli, W.

    2009-01-01

    For single phase flow meters more and better non-intrusive or even clamp-on meters become available. This allows for a wider use of meters and for easier flow control. As the demand for multiphase meters is increasing, the current aim is to develop a non-intrusive multiphase flow meter. The non-intr

  20. Axisymmetric multiphase lattice Boltzmann method for generic equations of state

    NARCIS (Netherlands)

    Reijers, S.A.; Gelderblom, H.; Toschi, F.

    2016-01-01

    We present an axisymmetric lattice Boltzmann model based on the Kupershtokh et al. multiphase model that is capable of solving liquid–gas density ratios up to 103. Appropriate source terms are added to the lattice Boltzmann evolution equation to fully recover the axisymmetric multiphase conservation

  1. On the mixture model for multiphase flow

    Energy Technology Data Exchange (ETDEWEB)

    Manninen, M.; Taivassalo, V. [VTT Energy, Espoo (Finland). Nuclear Energy; Kallio, S. [Aabo Akademi, Turku (Finland)

    1996-12-31

    Numerical flow simulation utilising a full multiphase model is impractical for a suspension possessing wide distributions in the particle size or density. Various approximations are usually made to simplify the computational task. In the simplest approach, the suspension is represented by a homogeneous single-phase system and the influence of the particles is taken into account in the values of the physical properties. This study concentrates on the derivation and closing of the model equations. The validity of the mixture model is also carefully analysed. Starting from the continuity and momentum equations written for each phase in a multiphase system, the field equations for the mixture are derived. The mixture equations largely resemble those for a single-phase flow but are represented in terms of the mixture density and velocity. The volume fraction for each dispersed phase is solved from a phase continuity equation. Various approaches applied in closing the mixture model equations are reviewed. An algebraic equation is derived for the velocity of a dispersed phase relative to the continuous phase. Simplifications made in calculating the relative velocity restrict the applicability of the mixture model to cases in which the particles reach the terminal velocity in a short time period compared to the characteristic time scale of the flow of the mixture. (75 refs.)

  2. Multiphasic interactions between nucleotides and target proteins

    CERN Document Server

    Nissen, Per

    2016-01-01

    The nucleotides guanosine tetraphosphate (ppGpp) and guanosine pentaphosphate (pppGpp) bind to target proteins to promote bacterial survival (Corrigan et al. 2016). Thus, the binding of the nucleotides to RsgA, a GTPase, inhibits the hydrolysis of GTP. The dose response, taken to be curvilinear with respect to the logarithm of the inhibitor concentration, is instead much better (P<0.001 when the 6 experiments are combined) represented as multiphasic, with high to exceedingly high absolute r values for the straight lines, and with transitions in the form of non-contiguities (jumps). Profiles for the binding of radiolabeled nucleotides to HprT and Gmk, GTP synthesis enzymes, were, similarly, taken to be curvilinear with respect to the logarithm of the protein concentration. However, the profiles are again much better represented as multiphasic than as curvilinear (the P values range from 0.047 to <0.001 for each of the 8 experiments for binding of ppGpp and pppGpp to HprT). The binding of GTP to HprT and ...

  3. Multiphase equation of state for iron

    Energy Technology Data Exchange (ETDEWEB)

    Kerley, G I

    1993-02-01

    The PANDA code is used to build a multiphase equation of state (EOS) table for iron. Separate EOS tables were first constructed for each of the individual phases. The phase diagram and multiphase EOS were then determined from the Helmholtz free energies. The model includes four solid phases ([alpha],[gamma], [delta], and [var epsilon]) and a fluid phase (including the liquid, vapor, and supercritical regions). The model gives good agreement with experimental thermophysical data, static compression data, phase boundaries, and shock-wave measurements. Contributions from thermal electronic excitation, computed from a quantum-statistical-mechanical model, were found to be very important. This EOS covers a wide range of densities (0--1000 g/cm[sup 3]) and temperatures (0--1.2[times]10[sup 7] K). It is also applicable to RHA steel. The new EOS is used in hydrocode simulations of plate impact experiments, a nylon ball impact on steel, and the shaped charge perforation of an RHA plate. The new EOS table can be accessed through the SNL-SESAME library as material number 2150.

  4. Cause and Effect of Feedback: Multiphase Gas in Cluster Cores Heated by AGN Jets

    CERN Document Server

    Gaspari, M; Sharma, P

    2011-01-01

    Multiwavelength data indicate that the X-ray emitting plasma in the cores of galaxy clusters is not cooling catastrophically. To large extent, cooling is offset by heating due to active galactic nuclei (AGN) via jets. The cool-core clusters, with cooler/denser plasmas, show multiphase gas and signs of some cooling in their cores. These observations suggest that the cool core is locally thermally unstable while maintaining global thermal equilibrium. Using high-resolution, three-dimensional simulations we study the formation of multiphase gas in cluster cores heated by highly-collimated bipolar AGN jets. Our key conclusion is that spatially extended multiphase filaments form only when the instantaneous ratio of the thermal instability and free-fall timescales (t_TI/t_ff) falls below a critical threshold of \\approx 10. When this happens, dense cold gas decouples from the hot ICM phase and generates inhomogeneous and spatially extended Halpha filaments. These cold gas clumps and filaments `rain' down onto the ce...

  5. Development of an Efficient Meso- scale Multi-phase Flow Solver in Nuclear Applications

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Taehun [City Univ. (CUNY), NY (United States)

    2015-10-20

    The proposed research aims at formulating a predictive high-order Lattice Boltzmann Equation for multi-phase flows relevant to nuclear energy related application - namely, saturated and sub-cooled boiling in reactors, and liquid- liquid mixing and extraction for fuel cycle separation. An efficient flow solver will be developed based on the Finite Element based Lattice Boltzmann Method (FE- LBM), accounting for phase-change heat transfer and capable of treating multiple phases over length scales from the submicron to the meter. A thermal LBM will be developed in order to handle adjustable Prandtl number, arbitrary specific heat ratio, a wide range of temperature variations, better numerical stability during liquid-vapor phase change, and full thermo-hydrodynamic consistency. Two-phase FE-LBM will be extended to liquid–liquid–gas multi-phase flows for application to high-fidelity simulations building up from the meso-scale up to the equipment sub-component scale. While several relevant applications exist, the initial applications for demonstration of the efficient methods to be developed as part of this project include numerical investigations of Critical Heat Flux (CHF) phenomena in nuclear reactor fuel bundles, and liquid-liquid mixing and interfacial area generation for liquid-liquid separations. In addition, targeted experiments will be conducted for validation of this advanced multi-phase model.

  6. ON THE SELECTION OF DRUGS DOSAGE REGIMEN

    Directory of Open Access Journals (Sweden)

    E. N. Bochanova

    2015-09-01

    Full Text Available A complex system of hemostasis regulation, insufficient data on drugs pharmacokinetics, multiple factors effecting treatment, including patient’s adherence to therapy, that can lead to the need for the dosage regimen specification are presented.

  7. Discrete fracture modeling of multiphase flow and hydrocarbon production in fractured shale or low permeability reservoirs

    Science.gov (United States)

    Hao, Y.; Settgast, R. R.; Fu, P.; Tompson, A. F. B.; Morris, J.; Ryerson, F. J.

    2016-12-01

    It has long been recognized that multiphase flow and transport in fractured porous media is very important for various subsurface applications. Hydrocarbon fluid flow and production from hydraulically fractured shale reservoirs is an important and complicated example of multiphase flow in fractured formations. The combination of horizontal drilling and hydraulic fracturing is able to create extensive fracture networks in low permeability shale rocks, leading to increased formation permeability and enhanced hydrocarbon production. However, unconventional wells experience a much faster production decline than conventional hydrocarbon recovery. Maintaining sustainable and economically viable shale gas/oil production requires additional wells and re-fracturing. Excessive fracturing fluid loss during hydraulic fracturing operations may also drive up operation costs and raise potential environmental concerns. Understanding and modeling processes that contribute to decreasing productivity and fracturing fluid loss represent a critical component for unconventional hydrocarbon recovery analysis. Towards this effort we develop a discrete fracture model (DFM) in GEOS (LLNL multi-physics computational code) to simulate multiphase flow and transfer in hydraulically fractured reservoirs. The DFM model is able to explicitly account for both individual fractures and their surrounding rocks, therefore allowing for an accurate prediction of impacts of fracture-matrix interactions on hydrocarbon production. We apply the DFM model to simulate three-phase (water, oil, and gas) flow behaviors in fractured shale rocks as a result of different hydraulic stimulation scenarios. Numerical results show that multiphase flow behaviors at the fracture-matrix interface play a major role in controlling both hydrocarbon production and fracturing fluid recovery rates. The DFM model developed in this study will be coupled with the existing hydro-fracture model to provide a fully integrated

  8. Supernova Feedback and Multiphase Interstellar Medium

    Science.gov (United States)

    Li, Miao; Ostriker, Jeremiah P.; Cen, Renyue; Bryan, Greg; Naab, Thorsten

    2015-01-01

    Without feedback, galaxies in cosmological simulations fail to generate outflows and tend to be too massive and too centrally concentrated, in contrast to the prominent disks observed ubiquitously in our universe. The nature of supernova (SN) feedback remains, however, highly uncertain, and most galaxy simulations so far adopt ad hoc models. Here we perform parsec-resolution simulations of a patch of the interstellar medium (ISM), and show that the unresolved multiphase gas in cosmological simulations can greatly affect the SN feedback by allowing blastwaves to travel in-between the clouds. We also show how ISM clumping varies with the mean gas density and SN rate encountered in real galactic environments. We emphasize that the inhomogeneity of the ISM must be considered in coarse-resolution simulations. We discuss how the gas pressure maintained by SN explosions can help to launch the galactic winds, and compare our results with the sub-grid models adopted in current cosmological simulations.

  9. Reactive Chemical Transport Under Multiphase System

    Science.gov (United States)

    Fang, Y.; Yeh, G.

    2001-12-01

    A numerical model, HYDROBIOGEOCHEM, is developed for modeling reactive chemical transport under multiphase flow systems. The chemistry part of this model is derived from BIOGEOCHEM, which is a general computer code that simulates biogeochemial processes from a reaction-based mechanistic point of view. To reduce primary dependent variables (PDVs), Gauss-Jordan decomposition is applied to the governing matrix equations for transport, resulting in mobile components and mobile kinetic variables as PDVs. Options of sequential iteration approach (SIA), predictor corrector and operator splitting method are incorporated in the code to make it versatile. The model is a practical tool for assessing migration of subsurface contamination and proper designing of remediation technologies. Examples are presented to demonstrate the capability of the new model.

  10. Identifying layers in random multiphase structures

    Science.gov (United States)

    Mader, Kevin; Stampanoni, Marco

    2016-01-01

    X-Ray microscopic methods, benefiting from the large penetration depth of X-rays in many materials, enable 3D investigation of a wide variety of samples. This allows for a wide variety of physical, chemical, and biological structures to be seen and explored, in some cases even in real time. Such measurements have lead to insights into paleontology, vulcanology, genetics, and material science. The ability to see and visualize complex systems can provide otherwise unobtainable information on structure, interactions, mechanical behavior, and evolution. The field has, however, led to a massive amount of new, heterogenous, difficult to process data. We present a general, model-free approach for characterizing multiphase 3D systems and show how the method can be applied to experimental X-ray microscopy data to better understand and quantify layer structure in two typical systems: investigation of layered fibers and clay samples.

  11. Gasificaton Transport: A Multiphase CFD Approach & Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dimitri Gidaspow; Veeraya Jiradilok; Mayank Kashyap; Benjapon Chalermsinsuwan

    2009-02-14

    The objective of this project was to develop predictive theories for the dispersion and mass transfer coefficients and to measure them in the turbulent fluidization regime, using existing facilities. A second objective was to use our multiphase CFD tools to suggest optimized gasifier designs consistent with aims of Future Gen. We have shown that the kinetic theory based CFD codes correctly compute: (1) Dispersion coefficients; and (2) Mass transfer coefficients. Hence, the kinetic theory based CFD codes can be used for fluidized bed reactor design without any such inputs. We have also suggested a new energy efficient method of gasifying coal and producing electricity using a molten carbonate fuel cell. The principal product of this new scheme is carbon dioxide which can be converted into useful products such as marble, as is done very slowly in nature. We believe this scheme is a lot better than the canceled FutureGen, since the carbon dioxide is safely sequestered.

  12. Multiphase composites with extremal bulk modulus

    DEFF Research Database (Denmark)

    Gibiansky, L. V.; Sigmund, Ole

    2000-01-01

    This paper is devoted to the analytical and numerical study of isotropic elastic composites made of three or more isotropic phases. The ranges of their effective bulk and shear moduli are restricted by the Hashin-Shtrikman-Walpole (HSW) bounds. For two-phase composites, these bounds are attainable......, that is, there exist composites with extreme bulk and shear moduli. For multiphase composites, they may or may not be attainable depending on phase moduli and volume fractions. Sufficient conditions of attainability of the bounds and various previously known and new types of optimal composites...... are described. Most of our new results are related to the two-dimensional problem. A numerical topology optimization procedure that solves the inverse homogenization problem is adopted and used to look for two-dimensional three-phase composites with a maximal effective bulk modulus. For the combination...

  13. Online recognition of the multiphase flow regime

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The key reasons that the present method cannot be used to solve the industrial multi- phase flow pattern recognition are clarified firstly. The prerequisite to realize the online recognition is proposed and recognition rules for partial flow pattern are obtained based on the massive experimental data. The standard templates for every flow regime feature are calculated with self-organization cluster algorithm. The multi-sensor data fusion method is proposed to realize the online recognition of multiphase flow regime with the pressure and differential pressure signals, which overcomes the severe influence of fluid flow velocity and the oil fraction on the recognition. The online recognition method is tested in the practice, which has less than 10 percent measurement error. The method takes advantages of high confidence, good fault tolerance and less requirement of single sensor performance.

  14. Multiphase Flow Dynamics 5 Nuclear Thermal Hydraulics

    CERN Document Server

    Kolev, Nikolay Ivanov

    2012-01-01

    The present Volume 5 of the successful book package "Multiphase Flow Dynamics" is devoted to nuclear thermal hydraulics which is a substantial part of nuclear reactor safety. It provides knowledge and mathematical tools for adequate description of the process of transferring the fission heat released in materials due to nuclear reactions into its environment. It step by step introduces into the heat release inside the fuel, temperature fields in the fuels, the "simple" boiling flow in a pipe described using ideas of different complexity like equilibrium, non equilibrium, homogeneity, non homogeneity. Then the "simple" three-fluid boiling flow in a pipe is described by gradually involving the mechanisms like entrainment and deposition, dynamic fragmentation, collisions, coalescence, turbulence. All heat transfer mechanisms are introduced gradually discussing their uncertainty. Different techniques are introduced like boundary layer treatments or integral methods. Comparisons with experimental data at each step...

  15. Multiphase flow dynamics 5 nuclear thermal hydraulics

    CERN Document Server

    Kolev, Nikolay Ivanov

    2015-01-01

    This Volume 5 of the successful book package "Multiphase Flow Dynamics" is devoted to nuclear thermal hydraulics which is a substantial part of nuclear reactor safety. It provides knowledge and mathematical tools for adequate description of the process of transferring the fission heat released in materials due to nuclear reactions into its environment. It step by step introduces into the heat release inside the fuel, temperature fields in the fuels, the "simple" boiling flow in a pipe described using ideas of different complexity like equilibrium, non equilibrium, homogeneity, non homogeneity. Then the "simple" three-fluid boiling flow in a pipe is described by gradually involving the mechanisms like entrainment and deposition, dynamic fragmentation, collisions, coalescence, turbulence. All heat transfer mechanisms are introduced gradually discussing their uncertainty. Different techniques are introduced like boundary layer treatments or integral methods. Comparisons with experimental data at each step demons...

  16. Multiphasic MDCT in small bowel volvulus

    Energy Technology Data Exchange (ETDEWEB)

    Feng Shiting, E-mail: fst1977@163.com [Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, 58th The Second Zhongshan Road, Guangzhou 510080 (China); Chan Tao, E-mail: taochan@hku.hk [Department of Diagnostic Radiology, University of Hong Kong, Room 406, Block K, Queen Mary Hospital (Hong Kong); Sun Canhui, E-mail: canhuisun@sina.com [Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, 58th The Second Zhongshan Road, Guangzhou 510080 (China); Li Ziping, E-mail: liziping163@tom.com [Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, 58th The Second Zhongshan Road, Guangzhou 510080 (China); Guo Huanyi, E-mail: guohuanyi@163.com [Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, 58th The Second Zhongshan Road, Guangzhou 510080 (China); Yang Guangqi, E-mail: shwy03@126.com [Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, 58th The Second Zhongshan Road, Guangzhou 510080 (China); Peng Zhenpeng, E-mail: ppzhen@21cn.com [Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, 58th The Second Zhongshan Road, Guangzhou 510080 (China); Meng Quanfei, E-mail: mzycoco@gmail.com [Department of Radiology, The First Affiliated Hospital, Sun Yat-Sen University, 58th The Second Zhongshan Road, Guangzhou 510080 (China)

    2010-11-15

    Objective: Evaluate the use of MDCT with 3D CT angiography (CTA) and CT portal venography (CTPV) reconstruction for the diagnosis of small bowel volvulus (SBV). Methods: Multiphasic MDCT findings in nine patients (seven males and two females, age range 2-70) with surgically proven SBV were retrospectively reviewed. Non-contrast and double phase contrast enhanced MDCT including 3D CTA and CTPV reconstruction were performed in all the patients. Two experienced abdominal radiologists evaluated the images and defined the location, direction and degree of SBV. Results: On axial MDCT images, all cases show segmental or global dilatation of small intestine. Other findings include circumferential bowel wall thickening in eight cases, halo appearance and hyperemia in seven cases, whirl sign in six cases, beak-like appearance in six cases, closed loops in six cases and ascites in one case. CTA/CTPV showed abnormal courses involving main trunks of superior mesenteric artery (SMA) and superior mesenteric vein (SMV) in seven cases, with or without distortion of their tributaries. Normal course of SMA but abnormal course of SMV was seen in the other two cases. Of all the nine cases, whirl sign was seen in six cases and barber's pole sign in five cases. Dilated SMV was observed in eight cases and abrupt termination of SMA was found in one case. Compared with surgical findings, the location, direction and degree of SBV were correctly estimated in all cases based on CTA/CTPV. Conclusion: Multiphasic MDCT with CTA/CTPV reconstruction can play an important role in the diagnosis of SBV. The location, direction and degree of SBV can all be defined preoperatively using this method.

  17. 2nd International Conference on Multiphase Flow - ICMF '95

    CERN Document Server

    Fukano, T; Bataille, Jean

    1995-01-01

    There is increasing world-wide interest in obtaining an understanding of various multiphase flow phenomena and problems in terms of a common language of multiphase flow. This volume contains state-of-the-art papers which have been contributed from all over the world by experts working on all aspects of multiphase flows. The volume also highlights international technology-sharing in the fields of energy, environment and public health, in order to create a brighter and sustainable future for man and for all life in the next century. It is intended that this volume will serve as a major source of

  18. Multiphase Flow and Fluidization Continuum and Kinetic Theory Descriptions

    CERN Document Server

    Gidaspow, Dimitri

    1994-01-01

    Useful as a reference for engineers in industry and as an advanced level text for graduate engineering students, Multiphase Flow and Fluidization takes the reader beyond the theoretical to demonstrate how multiphase flow equations can be used to provide applied, practical, predictive solutions to industrial fluidization problems. Written to help advance progress in the emerging science of multiphase flow, this book begins with the development of the conservation laws and moves on through kinetic theory, clarifying many physical concepts (such as particulate viscosity and solids pressure) and i

  19. Modelling Dust Evolution in Galaxies with a Multiphase, Inhomogeneous ISM

    CERN Document Server

    Zhukovska, Svitlana; Jenkins, Edward B; Klessen, Ralf

    2016-01-01

    We develop a model of dust evolution in a multiphase, inhomogeneous ISM including dust growth and destruction processes. The physical conditions for grain evolution are taken from hydrodynamical simulations of giant molecular clouds in a Milky Way-like spiral galaxy. We improve the treatment of dust growth by accretion in the ISM to investigate the role of the temperature-dependent sticking coefficient and ion-grain interactions. From detailed observational data on the gas-phase Si abundances [Si/H]_{gas} measured in the local Galaxy, we derive a relation between the average [Si/H]_{gas} and the local gas density n(H) which we use as a critical constraint for the models. This relation requires a sticking coefficient that decreases with the gas temperature. The synthetic relation constructed from the spatial dust distribution reproduces the slope of -0.5 of the observed relation in cold clouds. This slope is steeper than that for the warm medium and is explained by the dust growth. We find that it occurs for a...

  20. Design and Development of Integrated Compact Multiphase Separation System (CMSS)

    Energy Technology Data Exchange (ETDEWEB)

    Ram S. Mohan; Ovadia Shoham

    2006-04-30

    The petroleum industry has relied in the past mainly on conventional vessel-type separators, which are bulky, heavy and expensive, to process wellhead production of oil-water-gas flow. Economic and operational pressures continue to force the petroleum industry to seek less expensive and more efficient separation alternatives in the form of compact separators. The compact dimensions, smaller footprint and lower weight of compact separators have a potential for cost savings to the industry, especially in offshore and subsea applications. Also, compact separators reduce the inventory of hydrocarbons significantly, which is critical for environmental This report presents a brief overview of the activities and tasks accomplished during the Budget Period II (October 09, 2004-April 30, 2006) of the DOE project titled ''Design and Development of Integrated Compact Multiphase Separation System (CMSS{copyright})''. An executive summary is presented initially followed by the tasks of the current budget period. Then, detailed description of the experimental and modeling investigations are presented. Subsequently, the technical and scientific results of the activities of this project period are presented with discussions. The findings of this investigation are summarized in the ''Conclusions'' section In this investigation, the concept of CMSS{copyright} has been developed and is proven through simulation studies and validated by experimental data. As part of the second phase of the project (Budget Period II--10/09/2004-04/30/2006) experimental investigation of the integrated CMSS{copyright} for different configurations has been conducted in order to evaluate the performance of the individual separation components, and determine how they will affect the performance of each other when integrated in the CMSS{copyright}. An intelligent control system is also developed to improve the total system efficiency of Compact Multiphase Separation

  1. Development of predictive simulation capability for reactive multiphase flow

    Energy Technology Data Exchange (ETDEWEB)

    VanderHeyden, W.B.; Kendrick, B.K.

    1998-12-31

    This is the final report of a Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of the project was to develop a self-sustained research program for advanced computer simulation of industrial reactive multiphase flows. The prototype research problem was a three-phase alumina precipitator used in the Bayer process, a key step in aluminum refining. Accomplishments included the development of an improved reaction mechanism of the alumina precipitation growth process, the development of an efficient methods for handling particle size distribution in multiphase flow simulation codes, the incorporation of precipitation growth and agglomeration kinetics in LANL's CFDLIB multiphase flow code library and the evaluation of multiphase turbulence closure models for bubbly flow simulations.

  2. Application of Multiphase Particle Methods in Atomization and Breakup Regimes of Liquid Jets

    CERN Document Server

    Farrokhpanah, Amirsaman

    2016-01-01

    Multiphase Smoothed Particle Hydrodynamics (SPH) method has been used to study the jet breakup phenomena. It has been shown that this method is well capable of capturing different jet breakup characteristics. The value obtained for critical Weber number here in transition from dripping to jetting is a very good match to available values in literature. Jet breakup lengths are also agreeing well with several empirical correlations. Successful usage of SPH, as a comparably fast CFD solver, in jet breakup analysis helps in speeding up the numerical study of this phenomenon.

  3. Relationship between Multi-Phase Formation and Molecular Structure for Liquid Crystal System

    Institute of Scientific and Technical Information of China (English)

    LI Zhenxin; MA Heng; LI Shipu

    2005-01-01

    A mechanical model of liquid crystals ( LCs ) was used to explain the phase formation and thermal properties. The LC phases in the model are micro-machine systems consisting of an ensemble of molecular rotors, and some dynamic parameters in a semi-experiment molecular orbit method. A novel explanation on the multi-phase formation of LC system is obtained. It is found that the value of the critical rotational velocity is a key parameter for the characterization of each homologous series. The dipole moment of the molecules was also discussed.

  4. Influence of different factors on momentum transfer in mechanically agitated multiphase systems

    Directory of Open Access Journals (Sweden)

    Cudak Magdalena

    2016-03-01

    Full Text Available A comparative analysis concerning the influence of different factors on momentum transfer in mechanically agitated systems was carried out on the basis of experimental results for solid-liquid, gas-liquid and gas-solid-liquid systems. The effects of the impeller - baffles system geometry, scale of the agitated vessel, type and number of impellers and their off-bottom clearance, as well as physical properties of the multiphase systems on the critical impeller speeds needed to produce suspension or dispersion, power consumption and gas hold-up were analysed and evaluated.

  5. Fundamentals of Turbulent and Multi-Phase Combustion

    CERN Document Server

    Kuo, Kenneth Kuan-yun

    2012-01-01

    Detailed coverage of advanced combustion topics from the author of Principles of Combustion, Second Edition Turbulence, turbulent combustion, and multiphase reacting flows have become major research topics in recent decades due to their application across diverse fields, including energy, environment, propulsion, transportation, industrial safety, and nanotechnology. Most of the knowledge accumulated from this research has never been published in book form-until now. Fundamentals of Turbulent and Multiphase Combustion presents up-to-date, integrated coverage of the fundamentals of turbulence

  6. Numerical simulation of multiphase cavitating flows around an underwater projectile

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The present simulation investigates the multiphase cavitating flow around an underwater projectile.Based on the Homogeneous Equilibrium Flow assumption,a mixture model is applied to simulate the multiphase cavitating flow including ventilated cavitation caused by air injection as well as natural cavitation that forms in a region where the pressure of liquid falls below its vapor pressure. The transport equation cavitating model is applied.The calculations are executed based on a suite of CFD code.The hyd...

  7. Prophylactic antibiotic regimens in tumour surgery (PARITY)

    DEFF Research Database (Denmark)

    Petersen, Michael Mørk; Hettwer, Werner H; Grum-Schwensen, Tomas

    2015-01-01

    -day regimen of post-operative antibiotics, in comparison to a 24-hour regimen, decreases surgical site infections in patients undergoing endoprosthetic reconstruction for lower extremity primary bone tumours. METHODS: We performed a pilot international multi-centre RCT. We used central randomisation......% at one year (the remainder with partial data or pending queries). In total, 18 participants missed at least one dose of antibiotics or placebo post-operatively, but 93% of all post-operative doses were administered per protocol. CONCLUSIONS: It is feasible to conduct a definitive multi-centre RCT of post-operative...... to conceal treatment allocation and sham antibiotics to blind participants, surgeons, and data collectors. We determined feasibility by measuring patient enrolment, completeness of follow-up, and protocol deviations for the antibiotic regimens. RESULTS: We screened 96 patients and enrolled 60 participants...

  8. FOREWORD: International Symposium of Cavitation and Multiphase Flow (ISCM 2014)

    Science.gov (United States)

    Wu, Yulin

    2015-01-01

    The International Symposium on Cavitation and Multiphase Flow (ISCM 2014) was held in Beijing, China during 18th-21st October, 2014, which was jointly organized by Tsinghua University, Beijing, China and Jiangsu University, Zhenjiang, China. The co-organizer was the State Key Laboratory of Hydroscience and Engineering, Beijing, China. Cavitation and multiphase flow is one of paramount topics of fluid mechanics with many engineering applications covering a broad range of topics, e.g. hydraulic machinery, biomedical engineering, chemical and process industry. In order to improve the performances of engineering facilities (e.g. hydraulic turbines) and to accelerate the development of techniques for medical treatment of serious diseases (e.g. tumors), it is essential to improve our understanding of cavitation and Multiphase Flow. For example, the present development towards the advanced hydrodynamic systems (e.g. space engine, propeller, hydraulic machinery system) often requires that the systems run under cavitating conditions and the risk of cavitation erosion needs to be controlled. The purpose of the ISCM 2014 was to discuss the state-of-the-art cavitation and multiphase flow research and their up-to-date applications, and to foster discussion and exchange of knowledge, and to provide an opportunity for the researchers, engineers and graduate students to report their latest outputs in these fields. Furthermore, the participants were also encouraged to present their work in progress with short lead time and discuss the encountered problems. ISCM 2014 covers all aspects of cavitation and Multiphase Flow, e.g. both fundamental and applied research with a focus on physical insights, numerical modelling and applications in engineering. Some specific topics are: Cavitating and Multiphase Flow in hydroturbines, pumps, propellers etc. Numerical simulation techniques Cavitation and multiphase flow erosion and anti-erosion techniques Measurement techniques for cavitation and

  9. Lattice Boltzmann Simulation of Multiphase Transport in Nanostructured PEM Fuel Cells

    Science.gov (United States)

    Stiles, Christopher D.

    As the fossil fuel crisis becomes more critical, it is imperative to develop renewable sources of power generation. Polymer electrolyte membrane (PEM) fuel cells are considered a viable option. However, the cost of the platinum catalyst has hindered their commercialization. PEM fuel cells with platinum loading of >0.4 mg cm2 are common. Efforts towards further reducing this loading are currently underway utilizing nanostructured electrodes. A consequence of increased platinum utilization per unit area and thinner nanostructured electrodes is flooding, which is detrimental to fuel cell performance. Flooding causes a two-fold impact on cell performance: a drop in cell voltage and a rise in parasitic pumping power to overcome the increased pressure drop, which together result in a significant reduction in system efficiency. Proper water management is therefore crucial for optimum performance of the fuel cell and also for enhancing membrane durability. The goal of this thesis is to simulate the multiphase fluid transport in the nanostructured PEMFC of H2O in air with realistic density ratios. In order to pursue this goal, the ability of the pseudopotential based multiphase lattice Boltzmann method to realistically model the coexistence of the gas and liquid phases of H2O at low temperatures is explored. This method is expanded to include a gas mixture of O2 and N 2 into the multiphase H2O systems. Beginning with the examination of the phase transition region described by the current implementation of the multiphase pseudopotential lattice Boltzmann model. Following this, a modified form of the pressure term with the use of a scalar multiplier kappa for the Peng-Robinson equation of state is thoroughly investigated. This method proves to be very effective at enabling numerically stable simulations at low temperatures with large density ratios. It is found that for decreasing values of kappa, this model leads to an increase in multiphase interface thickness and a

  10. Quantitative tomographic measurements of opaque multiphase flows

    Energy Technology Data Exchange (ETDEWEB)

    GEORGE,DARIN L.; TORCZYNSKI,JOHN R.; SHOLLENBERGER,KIM ANN; O' HERN,TIMOTHY J.; CECCIO,STEVEN L.

    2000-03-01

    An electrical-impedance tomography (EIT) system has been developed for quantitative measurements of radial phase distribution profiles in two-phase and three-phase vertical column flows. The EIT system is described along with the computer algorithm used for reconstructing phase volume fraction profiles. EIT measurements were validated by comparison with a gamma-densitometry tomography (GDT) system. The EIT system was used to accurately measure average solid volume fractions up to 0.05 in solid-liquid flows, and radial gas volume fraction profiles in gas-liquid flows with gas volume fractions up to 0.15. In both flows, average phase volume fractions and radial volume fraction profiles from GDT and EIT were in good agreement. A minor modification to the formula used to relate conductivity data to phase volume fractions was found to improve agreement between the methods. GDT and EIT were then applied together to simultaneously measure the solid, liquid, and gas radial distributions within several vertical three-phase flows. For average solid volume fractions up to 0.30, the gas distribution for each gas flow rate was approximately independent of the amount of solids in the column. Measurements made with this EIT system demonstrate that EIT may be used successfully for noninvasive, quantitative measurements of dispersed multiphase flows.

  11. Multiphase flow metering: 4 years on

    Energy Technology Data Exchange (ETDEWEB)

    Falcone, G.; Hewitt, G.F.; Alimonti, C.; Harrison, B.

    2005-07-01

    Since the authors' last review in 2001 [1], the use of Multiphase Flow Metering (MFM) within the oil and gas industry continues to grow apace, being more popular in some parts of the world than others. Since the early 1990's, when the first commercial meters started to appear, there have been more than 1,600 field applications of MFM for field allocation, production optimisation and mobile well testing. As the authors predicted, wet gas metering technology has improved to such an extent that its use has rapidly increased worldwide. A ''who's who'' of the MFM sector is provided, which highlights the mergers in the sector and gives an insight into the meters and measurement principles available today. Cost estimates, potential benefits and reliability in the field of the current MFM technologies are revisited and brought up to date. Several measurements technologies have resurfaced, such as passive acoustic energy patterns, infrared wavelengths, Nuclear Magnetic Resonance (NMR) and Electrical Capacitance Tomography (ECT), and they are becoming commercial. The concept of ''virtual metering'', integrated with ''classical MFM'', is now widely accepted. However, sometimes the principles of the MFM measurements themselves are forgotten, submerged in the sales and marketing hype. (author) (tk)

  12. Multiphase groundwater flow near cooling plutons

    Science.gov (United States)

    Hayba, D.O.; Ingebritsen, S.E.

    1997-01-01

    We investigate groundwater flow near cooling plutons with a computer program that can model multiphase flow, temperatures up to 1200??C, thermal pressurization, and temperature-dependent rock properties. A series of experiments examines the effects of host-rock permeability, size and depth of pluton emplacement, single versus multiple intrusions, the influence of a caprock, and the impact of topographically driven groundwater flow. We also reproduce and evaluate some of the pioneering numerical experiments on flow around plutons. Host-rock permeability is the principal factor influencing fluid circulation and heat transfer in hydrothermal systems. The hottest and most steam-rich systems develop where permeability is of the order of 10-15 m2. Temperatures and life spans of systems decrease with increasing permeability. Conduction-dominated systems, in which permeabilities are ???10-16m2, persist longer but exhibit relatively modest increases in near-surface temperatures relative to ambient conditions. Pluton size, emplacement depth, and initial thermal conditions have less influence on hydrothermal circulation patterns but affect the extent of boiling and duration of hydrothermal systems. Topographically driven groundwater flow can significantly alter hydrothermal circulation; however, a low-permeability caprock effectively decouples the topographically and density-driven systems and stabilizes the mixing interface between them thereby defining a likely ore-forming environment.

  13. Shock driven multiphase flow with particle evaporation

    Science.gov (United States)

    Dahal, Jeevan; McFarland, Jacob

    2016-11-01

    The computational study of the shock driven instability of a multiphase system with particle evaporation is presented. The particle evaporation modifies the evolution of the interface due to the addition of the vapor phase to the gas. The effects can be quantitatively measured by studying various gas parameters like density, temperature, vorticity and particle properties like diameter and temperature. In addition, the size distribution of particles also modifies the development of instability as the larger size particles damp the evolution of interface in comparison to the smaller size particles. The simulation results are presented to study these effects using FLASH developed at the FLASH Center at the University of Chicago. The capabilities of FLASH for particle modeling were extended using the Particle in Cell (PIC) technique for coupling of mass, momentum, and energy between the particle and carrier gas. A seeded cylinder of gas with particles having either a single radius or a distribution of radii was studied. The enstrophy production and destruction mechanisms were explored to understand the reason for change in vorticity with particle size.

  14. Dan Joseph's contributions to disperse multiphase flow

    Science.gov (United States)

    Prosperetti, Andrea

    2012-11-01

    During his distinguished career, Dan Joseph worked on a vast array of problems. One of these, which occupied him off and on over the last two decades of his life, was that of flows with suspended finite-size particles at finite Reynolds numbers. He realized early on that progress in this field had to rely on the insight gained from numerical simulation, an area in which he was a pioneer. On the basis of the early numerical results he recognized the now famous ``drafting, kissing and tumbling'' mechanism of particle-particle interaction, the possibility of fluidization by lift and many others. With a number of colleagues and a series of gifted students he produced a significant body of work summarized in his on-line book Interrogations of Direct Numerical Simulation of Solid-Liquid Flows available from http://www.efluids.com/efluids/books/joseph.htm. This presentation will describe Joseph's contribution to the understanding of disperse multiphase flow and conclude with some examples from the author's recent work in this area. Supported by NSF.

  15. Intravenous and intramuscular magnesium sulphate regimens in ...

    African Journals Online (AJOL)

    1993-09-03

    Sep 3, 1993 ... Pritchard' and a continuous intravenous (IV) infusion described by Zuspan! ... in the treatment of severe pre-eclampsia with the IM regimen of ..... people under the age of 50 years and more men died than women. In 40% of ...

  16. Workshop on Scientific Issues in Multiphase Flow

    Energy Technology Data Exchange (ETDEWEB)

    Hanratty, Thomas J. [Univ. of Illinois, Urbana, IL (United States)

    2003-01-02

    This report outlines scientific issues whose resolution will help advance and define the field of multiphase flow. It presents the findings of four study groups and of a workshop sponsored by the Program on Engineering Physics of the Department of Energy. The reason why multiphase flows are much more difficult to analyze than single phase flows is that the phases assume a large number of complicated configurations. Therefore, it should not be surprising that the understanding of why the phases configure in a certain way is the principal scientific issue. Research is needed which identifies the microphysics controlling the organization of the phases, which develops physical models for the resultant multi-scale interactions and which tests their validity in integrative experiments/theories that look at the behavior of a system. New experimental techniques and recently developed direct numerical simulations will play important roles in this endeavor. In gas-liquid flows a top priority is to develop an understanding of why the liquid phase in quasi fully-developed pipe flow changes from one configuration to another. Mixing flows offer a more complicated situation in which several patterns can exist at the same time. They introduce new physical challenges. A second priority is to provide a quantitative description of the phase distribution for selected fully-developed flows and for simple mixing flows (that could include heat transfer and phase change). Microphysical problems of interest are identified – including the coupling of molecular and macroscopic behavior that can be observed in many situations and the formation/destruction of interfaces in the coalescence/breakup of drops and bubbles. Solid-fluid flows offer a simpler system in that interfaces are not changing. However, a variety of patterns exist, that depend on the properties of the particles, their concentration and the Reynolds number characterizing the relative velocity. A top priority is the

  17. Modeling Dust Evolution in Galaxies with a Multiphase, Inhomogeneous ISM

    Science.gov (United States)

    Zhukovska, Svitlana; Dobbs, Clare; Jenkins, Edward B.; Klessen, Ralf S.

    2016-11-01

    We develop a model of dust evolution in a multiphase, inhomogeneous interstellar medium (ISM) using hydrodynamical simulations of giant molecular clouds in a Milky Way-like spiral galaxy. We improve the treatment of dust growth by accretion in the ISM to investigate the role of the temperature-dependent sticking coefficient and ion-grain interactions. From detailed observational data on the gas-phase Si abundances [{{Si}}{gas}/{{H}}] measured in the local Galaxy, we derive a relation between the average [{{Si}}{gas}/{{H}}] and the local gas density n({{H}}) that we use as a critical constraint for the models. This relation requires a sticking coefficient that decreases with the gas temperature. The relation predicted by the models reproduces the slope of -0.5 for the observed relation in cold clouds, which is steeper than that for the warm medium and is explained by dust growth. We find that growth occurs in the cold medium for all adopted values of the minimum grain size a min from 1 to 5 nm. For the classical cutoff of {a}\\min =5 {nm}, the Coulomb repulsion results in slower accretion and higher [{{Si}}{gas}/{{H}}] than the observed values. For {a}\\min ≲ 3 {nm}, the Coulomb interactions enhance the growth rate, steepen the slope of the [{{Si}}{gas}/{{H}}]-n({{H}}) relation, and provide a better match to observations. The rates of dust re-formation in the ISM by far exceed the rates of dust production by stellar sources. After the initial 140 Myr, the cycle of matter in and out of dust reaches a steady state, in which the dust growth balances the destruction on a similar timescale of 350 Myr.

  18. DESIGN AND DEVELOPMENT OF INTEGRATED COMPACT MULTIPHASE SEPARATION SYSTEM (CMSS)

    Energy Technology Data Exchange (ETDEWEB)

    Ram S. Mohan; Ovadia Shoham

    2004-12-31

    The petroleum industry has relied in the past mainly on conventional vessel-type separators, which are bulky, heavy and expensive, to process wellhead production of oil-water-gas flow. Economic and operational pressures continue to force the petroleum industry to seek less expensive and more efficient separation alternatives in the form of compact separators. The compact dimensions, smaller footprint and lower weight of compact separators have a potential for cost savings to the industry, especially in offshore and subsea applications. Also, compact separators reduce the inventory of hydrocarbons significantly, which is critical for environmental and safety considerations. This report presents a brief overview of the activities and tasks accomplished during the part July 09, 2003--October 08, 2004, related to the Budget Period I (July 09, 2003--October 08, 2004) of the DOE project titled ''Design and Development of Integrated Compact Multiphase Separation System (CMSS{copyright})''. An executive summary is presented initially followed by the tasks of the current budget period. Then, detailed description of the experimental and modeling investigations are presented. Subsequently, the technical and scientific results of the activities of this project period are presented with discussions. The findings of this investigation are summarized in the ''Conclusions'' section followed by relevant references. The initial phase of the project (Budget Period I--07/09/2003 to 10/08/2004) focuses on the development of additional individual compact separation components, such as the horizontal pipe separator (HPS{copyright}), for obtaining clean oil stream from oil-water mixture, flow conditioning components, such as the helical pipe (HP) and slug damper (SD{copyright}), for dissipating slugs upstream of the compact separators. The project will also design and test an upstream slug generator (SG).

  19. Small renal Oncocytomas: Differentiation with multiphase CT

    Energy Technology Data Exchange (ETDEWEB)

    Gakis, Georgios, E-mail: georgios.gakis@web.de [Department of Urology, University Hospital Tuebingen, Eberhard-Karls University, Hoppe-Seyler Strasse 3, Tuebingen (Germany); Kramer, Ulrich [Department of Radiology, University Hospital Tuebingen, Eberhard-Karls University, Tuebingen (Germany); Schilling, David; Kruck, Stephan; Stenzl, Arnulf [Department of Urology, University Hospital Tuebingen, Eberhard-Karls University, Hoppe-Seyler Strasse 3, Tuebingen (Germany); Schlemmer, Hans-Peter [Department of Radiology, University Hospital Tuebingen, Eberhard-Karls University, Tuebingen (Germany)

    2011-11-15

    Objectives: To evaluate characteristic imaging findings of tumor attenuation in multiphase computed tomography (CT) between renal oncocytomas and clear-cell renal cell carcinoma (ccRCC) of small tumor size ({<=}5 cm). Methods: We retrospectively identified 20 patients with complete four-phase CT with either histologically confirmed small renal oncocytoma (N = 10) or ccRCC (N = 10) who underwent subsequent total or partial nephrectomy. Exclusion criteria for RCC were non-clear-cell components in histology and a tumor diameter >5 cm. The relative attenuation of solid renal lesions and normal renal cortex was determined in the unenhanced, corticomedullary, nephrographic and excretory phase. Statistical comparison was carried out by Wilcoxon Rank Sum Test. Results: Mean tumor size of renal oncocytomas was 2.8 {+-} 0.4 cm (1.2-5) and of ccRCC 2.5 {+-} 0.2 cm (1.7-4.4; p = 0.57). All lesions were homogenous without extended areas of necroses. In the nephrographic phase, the difference of attenuation between renal cortex and tumor lesion was highest in both entities (oncocytoma, 48.1 {+-} 5.2 HU; ccRCC, 67.5 {+-} 12.1) but not between entities (p = 0.30). In the corticomedullary phase, renal oncocytomas showed greater isodensity to the normal renal cortex (13.9 {+-} 4.3 HU) compared to clear-cell RCC (51.5 {+-} 5.0 HU; p = 0.003). No further significant differences were found for the unenhanced and excretory phase. Conclusions: In this study, the maximum tumor-to-kidney contrast coincided with the nephrographic phase which was thus the most reliable for the detection of a renal lesion <5 cm. For lesion characterization, the corticomedullary phase was most useful for differentiating both entities. This finding is particularly important for the preoperative planning of a partial nephrectomy.

  20. MSTS - Multiphase Subsurface Transport Simulator theory manual

    Energy Technology Data Exchange (ETDEWEB)

    White, M.D.; Nichols, W.E.

    1993-05-01

    The US Department of Energy, through the Yucca Mountain Site Characterization Project Office, has designated the Yucca Mountain site in Nevada for detailed study as the candidate US geologic repository for spent nuclear fuel and high-level radioactive waste. Site characterization will determine the suitability of the Yucca Mountain site for the potential waste repository. If the site is determined suitable, subsequent studies and characterization will be conducted to obtain authorization from the Nuclear Regulatory Commission to construct the potential waste repository. A principal component of the characterization and licensing processes involves numerically predicting the thermal and hydrologic response of the subsurface environment of the Yucca Mountain site to the potential repository over a 10,000-year period. The thermal and hydrologic response of the subsurface environment to the repository is anticipated to include complex processes of countercurrent vapor and liquid migration, multiple-phase heat transfer, multiple-phase transport, and geochemical reactions. Numerical simulators based on mathematical descriptions of these subsurface phenomena are required to make numerical predictions of the thermal and hydrologic response of the Yucca Mountain subsurface environment The engineering simulator called the Multiphase Subsurface Transport Simulator (MSTS) was developed at the request of the Yucca Mountain Site Characterization Project Office to produce numerical predictions of subsurface flow and transport phenomena at the potential Yucca Mountain site. This document delineates the design architecture and describes the specific computational algorithms that compose MSTS. Details for using MSTS and sample problems are given in the {open_quotes}User`s Guide and Reference{close_quotes} companion document.

  1. Viscous and gravitational fingering in multiphase compositional and compressible flow

    Science.gov (United States)

    Moortgat, Joachim

    2016-03-01

    Viscous and gravitational fingering refer to flow instabilities in porous media that are triggered by adverse mobility or density ratios, respectively. These instabilities have been studied extensively in the past for (1) single-phase flow (e.g., contaminant transport in groundwater, first-contact-miscible displacement of oil by gas in hydrocarbon production), and (2) multi-phase immiscible and incompressible flow (e.g., water-alternating-gas (WAG) injection in oil reservoirs). Fingering in multiphase compositional and compressible flow has received much less attention, perhaps due to its high computational complexity. However, many important subsurface processes involve multiple phases that exchange species. Examples are carbon sequestration in saline aquifers and enhanced oil recovery (EOR) by gas or WAG injection below the minimum miscibility pressure. In multiphase flow, relative permeabilities affect the mobility contrast for a given viscosity ratio. Phase behavior can also change local fluid properties, which can either enhance or mitigate viscous and gravitational instabilities. This work presents a detailed study of fingering behavior in compositional multiphase flow in two and three dimensions and considers the effects of (1) Fickian diffusion, (2) mechanical dispersion, (3) flow rates, (4) domain size and geometry, (5) formation heterogeneities, (6) gravity, and (7) relative permeabilities. Results show that fingering in compositional multiphase flow is profoundly different from miscible conditions and upscaling techniques used for the latter case are unlikely to be generalizable to the former.

  2. Non-adherence to medication regimens among older African-American adults.

    Science.gov (United States)

    Bazargan, Mohsen; Smith, James; Yazdanshenas, Hamed; Movassaghi, Masoud; Martins, David; Orum, Gail

    2017-07-25

    of their medications, compared with participants with high drug regimen complexity index. While other studies have documented that non-adherence remains an important issue among older adults, our study shows that for underserved elderly African Americans, these issues are particularly striking. A periodic comprehensive assessment of all medications that they use remains a critical initial step to identify medication related issues. Assessment of their disease and medication related knowledge (e.g., therapeutic purposes, side-effects, special instructions, etc.) and their ability to follow complicated medication regimens and modification of their drug regimens requires inter-professional collaboration.

  3. Investigation on the gas pockets in a rotodynamic multiphase pump

    Science.gov (United States)

    Zhang, J. Y.; Li, Y. J.; Cai, S. J.; Zhu, H. W.; Zhang, Y. X.

    2016-05-01

    The appearance of gas pockets has an obvious impact on the performance of the rotodynamic multiphase pump. In order to study the formation of gas pockets in the pump and its effects on pump's performance, the unsteady numerical simulation and the visualization experiments were done to investigate gas pockets in a three-stage rotodynamic multiphase pump developed by authors. Meanwhile, the mixture of water and air was selected as the medium. According to the distributions of pressure, gas volume fraction and velocity vector in three compression cells in unsteady flow process, the process of the formation of gas pockets in the pump were analysed generally. The visualization experiments were used to verify the validity of the numerical simulation. The results will be benefit for the hydraulic design of the compression cell of rotodynamic multiphase pump.

  4. Viscous and Gravitational Fingering in Multiphase Compositional and Compressible Flow

    CERN Document Server

    Moortgat, Joachim

    2016-01-01

    Viscous and gravitational fingering refer to flow instabilities in porous media that are triggered by adverse mobility or density ratios, respectively. These instabilities have been studied extensively in the past for 1) single-phase flow (e.g., contaminant transport in groundwater, first-contact-miscible displacement of oil by gas in hydrocarbon production), and 2) multi-phase immiscible and incompressible flow (e.g., water-alternating-gas (WAG) injection in oil reservoirs). Fingering in multiphase compositional and compressible flow has received much less attention, perhaps due to its high computational complexity. However, many important subsurface processes involve multiple phases that exchange species. Examples are carbon sequestration in saline aquifers and enhanced oil recovery (EOR) by gas or WAG injection below the minimum miscibility pressure. In multiphase flow, relative permeabilities affect the mobility contrast for a given viscosity ratio. Phase behavior can also change local fluid properties, w...

  5. Electrification of particulates in industrial and natural multiphase flows

    CERN Document Server

    Gu, Zhaolin

    2017-01-01

    This book introduces comprehensive fundamentals, numerical simulations and experimental methods of electrification of particulates entrained multiphase flows. The electrifications of two particulate forms, liquid droplets and solid particles, are firstly described together. Liquid droplets can be charged under preset or associated electric fields, while solid particles can be charged through contact. Different charging ways in gas (liquid)-liquid or gas-solid multiphase flows are summarized, including ones that are beneficial to industrial processes, such as electrostatic precipitation, electrostatic spraying, and electrostatic separation, etc., ones harmful for shipping and powder industry, and ones occurring in natural phenomenon, such as wind-blown sand and thunderstorm. This book offers theoretical references to the control and utilization of the charging or charged particulates in multiphase flows as well.

  6. A Cell-Centered Multiphase ALE Scheme With Structural Coupling

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, Timothy Alan [Univ. of California, Davis, CA (United States)

    2012-04-16

    A novel computational scheme has been developed for simulating compressible multiphase flows interacting with solid structures. The multiphase fluid is computed using a Godunov-type finite-volume method. This has been extended to allow computations on moving meshes using a direct arbitrary-Eulerian- Lagrangian (ALE) scheme. The method has been implemented within a Lagrangian hydrocode, which allows modeling the interaction with Lagrangian structural regions. Although the above scheme is general enough for use on many applications, the ultimate goal of the research is the simulation of heterogeneous energetic material, such as explosives or propellants. The method is powerful enough for application to all stages of the problem, including the initial burning of the material, the propagation of blast waves, and interaction with surrounding structures. The method has been tested on a number of canonical multiphase tests as well as fluid-structure interaction problems.

  7. Multisensor Acquirement System of Electrokinetic in Multiphase Flow

    Directory of Open Access Journals (Sweden)

    Yahui Bu

    2013-09-01

    Full Text Available Streaming potential is one kind of electrokinetic effect coupled with fluid flow in porous media, and it has the ability to evaluate properties of rock and fluid in reservoirs. Geophysicists are much concerned about its application in geophysical survey, especially to monitor multiphase flow which is widespread in petroleum industry. To study the electrokinetic effect during multiphase flow, it is necessary to collect electrical and hydraulic parameters in real time. So we designed an acquisition system of multisensors (pressure, flow rate, electrical potential and resistivity, which could conduct measurement process automatically, introduced noise reduction algorithm to the primary analog signals. Data and control command were transmitted in network based on TCP/IP protocol and USB converter. Result from an water-oil displacement experiment showed that this system can effectively and rightly monitor the state of electrokinetic process during multiphase flow

  8. Dynamic effects in multiphase flow: A pore-scale network approach

    NARCIS (Netherlands)

    Gielen, T.; Hassanizadeh, S.M.; Leijnse, A.; Nordhaug, H.F.

    2005-01-01

    Current theories of multiphase flow rely on capillary pressure and saturation relationships that are commonly measured under static conditions. To incorporate transient behaviour, new multiphase flow theories have been proposed. These include an extended capillary pressure-saturation relationship

  9. Dynamic effects in multiphase flow: A pore-scale network approach

    NARCIS (Netherlands)

    Gielen, T.; Hassanizadeh, S.M.; Leijnse, A.; Nordhaug, H.F.

    2005-01-01

    Current theories of multiphase flow rely on capillary pressure and saturation relationships that are commonly measured under static conditions. To incorporate transient behaviour, new multiphase flow theories have been proposed. These include an extended capillary pressure-saturation relationship th

  10. Prophylactic antibiotic regimens in tumor surgery (PARITY survey

    Directory of Open Access Journals (Sweden)

    Hasan Khaled

    2012-06-01

    Full Text Available Abstract Background Deep infection following endoprosthetic limb reconstruction for sarcoma of the long bones is a devastating complication occurring in 15% of sarcoma patients. Optimizing infection protocols and conducting definitive surgical trials are critical to improving outcomes. In this study, the PARITY (Prophylactic Antibiotic Regimens in Tumor Surgery investigators aimed to examine surgeon preferences in antibiotic prophylaxis and perceptions about current evidence, as well as to ascertain interest in resolving uncertainty in the evidence with clinical trials. Methods We used a cross-sectional survey to examine current practice in the prescription of prophylactic antibiotics in Musculoskeletal Tumor Surgery. The survey was approved by our institution’s Ethics Board and emailed to all Active Members of the Musculoskeletal Tumor Society (MSTS and Canadian Orthopaedic Oncology Society (CANOOS. Survey answers were collected using an anonymous online survey tool. Results Of the 96 surgeons who received the questionnaire, 72 responded (75% response rate (% CI: 65.5, 82.5%. While almost all respondents agreed antibiotic regimens were important in reducing the risk of infection, respondents varied considerably in their choices of antibiotic regimens and dosages. Although 73% (95% CI: 61, 82% of respondents prescribe a first generation cephalosporin, 25% favor additional coverage with an aminoglycoside and/or Vancomycin. Of those who prescribe a cephalosporin, 33% prescribe a dosage of one gram for all patients and the reminder prescribe up to 2 grams based on body weight. One in three surgeons (95% CI: 25, 48% believes antibiotics could be discontinued after 24 hours but 40% (95% CI: 30, 53% continue antibiotics until the suction drain is removed. Given the ongoing uncertainty in evidence to guide best practices, 90% (95% CI: 81, 95% of respondents agreed that they would change their practice if a large randomized controlled trial showed

  11. Multi-phase SPH modelling of violent hydrodynamics on GPUs

    Science.gov (United States)

    Mokos, Athanasios; Rogers, Benedict D.; Stansby, Peter K.; Domínguez, José M.

    2015-11-01

    This paper presents the acceleration of multi-phase smoothed particle hydrodynamics (SPH) using a graphics processing unit (GPU) enabling large numbers of particles (10-20 million) to be simulated on just a single GPU card. With novel hardware architectures such as a GPU, the optimum approach to implement a multi-phase scheme presents some new challenges. Many more particles must be included in the calculation and there are very different speeds of sound in each phase with the largest speed of sound determining the time step. This requires efficient computation. To take full advantage of the hardware acceleration provided by a single GPU for a multi-phase simulation, four different algorithms are investigated: conditional statements, binary operators, separate particle lists and an intermediate global function. Runtime results show that the optimum approach needs to employ separate cell and neighbour lists for each phase. The profiler shows that this approach leads to a reduction in both memory transactions and arithmetic operations giving significant runtime gains. The four different algorithms are compared to the efficiency of the optimised single-phase GPU code, DualSPHysics, for 2-D and 3-D simulations which indicate that the multi-phase functionality has a significant computational overhead. A comparison with an optimised CPU code shows a speed up of an order of magnitude over an OpenMP simulation with 8 threads and two orders of magnitude over a single thread simulation. A demonstration of the multi-phase SPH GPU code is provided by a 3-D dam break case impacting an obstacle. This shows better agreement with experimental results than an equivalent single-phase code. The multi-phase GPU code enables a convergence study to be undertaken on a single GPU with a large number of particles that otherwise would have required large high performance computing resources.

  12. "Rescue" regimens after Helicobacter pylori treatment failure

    Institute of Scientific and Technical Information of China (English)

    Javier P Gisbert

    2008-01-01

    Helicobacter pylori (H pylori)infection is the main cause of gastritis,gastroduodenal ulcer disease,and gastric cancer.After more than 20 years of experience in Hpylori treatment,in my opinion,the ideal regimen to treat this infection is still to be found.Currently,apart from having to know first-line eradication regimens well,we must also be prepared to face lyeatment failures.Therefore,in designing a treatment strategy we should not focus on the results of primary therapy alone,but also on the final (overall) eradication rate.The choice of a "rescue" treatment depends on which treatment is used initially.If a clarithromycinbased regimen was used initially,a subsequent metronidazole-based treatment (quadruple therapy)may be used afterwards,and then a levofloxacinbased combination would be a third "rescue" option.Alternatively,it has recently been suggested that levofloxacin-based rescue therapy constitutes an encouraging second-line strategy,representing an alternative to quadruple therapy in patients with previous PPI-clarithromycin-amoxicillin failure,with the advantage of efficacy,simplicity and safety.In this case,a quadruple regimen may be reserved as a third-line rescue option.Finally,rifabutin-based rescue therapy constitutes an encouraging empirical fourthline strategy after multiple previous eradication failures with key antibiotics such as amoxicillin,clarithromycin,metronidazole,tetracycline,and levofloxacin.Even after two consecutive failures,several studies have demonstrated that H pylor/eradication can finally be achieved in almost all patients if several rescue therapies are consecutively given.Therefore,the attitude in H pylori eradication therapy failure,even after two or more unsuccessful attempts,should be to fight and not to surrender.

  13. New Treatment Regimen for Latent Tuberculosis Infection

    Centers for Disease Control (CDC) Podcasts

    2012-03-15

    In this podcast, Dr. Kenneth Castro, Director of the Division of Tuberculosis Elimination, discusses the December 9, 2011 CDC guidelines for the use of a new regimen for the treatment of persons with latent tuberculosis infection.  Created: 3/15/2012 by National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention (NCHHSTP).   Date Released: 3/15/2012.

  14. Experimental Study and Simulation Principles of An Oil-Gas Multiphase Transportation System

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    - Presented is an experimental study on the performance of an oil-gas multiphase transportation system, especially on the multiphase flow patterns, multiphase pumping and multiphase metering of the system. A dynamic simulation analysis is conducted to deduce simulation parameters of the system and similarity criteria under simplified conditions are obtained. The reliability and feasibility of two-phase flow experiment with oil and natural gas simulated by water and air are discussed by using the similarity criteria.

  15. National laboratories` capabilities summaries for the DOE Virtual Center for Multiphase Dynamics (VCMD)

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, E.L.

    1997-03-01

    The Virtual Center For Multiphase Dynamics (VCMD) integrates and develops the resources of industry, government, academia, and professional societies to enable reliable analysis in multiphase computational fluid dynamics. The primary means of the VCMD focus will be by the creation, support, and validation of a computerized simulation capability for multiphase flow and multiphase flow applications. This paper briefly describes the capabilities of the National Laboratories in this effort.

  16. Assessment of adherence to tuberculosis drug regimen

    Directory of Open Access Journals (Sweden)

    Khalili H.

    2008-03-01

    Full Text Available Background and the purpose of the study: Tuberculosis is curable if patients take sufficient uninterrupted therapy. Most experts acknowledge importance of patient adherence in efforts to control of the disease. This cross-sectional study was designed to evaluate the rate of compliance to anti-tuberculosis regimens by means of urine tests in newly diagnosed tuberculosis patients.Method: Investigation was carried out in Tehran University of Medical Sciences Teaching Hospitals, Tehran, IRAN. Fifty patients completed the study. The patients' urine samples were obtained at 0, 1, 2, 4 and 6 months of the study. Simple chemical methods were used to detect Isoniazid, Rifampin, and pyrazinamide, the three main drugs in tuberculosis treatment regimens. Urine tests at months of 0 and l of the study were considered as control tests.Results: After the first month, the patients' compliance was about 96%. At months of second, fourth and sixth, the whole adherence rates were 56 %, 76% and 81% respectively. Conclusion: About 30% of patients were non-compliant with treatment regimen which was more frequent than presumed; therefore detection of non-adherent patients is an essential subject in developing countries.

  17. Multiphasic acute disseminated encephalomyelitis associated with atypical rubella virus infection.

    Science.gov (United States)

    Shinoda, Koji; Asahara, Hideaki; Uehara, Taira; Miyoshi, Katsue; Suzuki, Satoshi O; Iwaki, Toru; Kira, Jun-ichi

    2015-02-01

    We report the first case of an occurrence of multiphasic acute disseminated encephalomyelitis (ADEM) associated with atypical rubella virus infection with no rash and long-term increased titers of serum anti-rubella IgM in a 17-year-old male who had no history of rubella vaccination. He suffered from at least six clinical exacerbations with disseminated hyperintense lesions on FLAIR MR images during the course of 18 months. Repeated methylprednisolone pulse therapy and intravenous immunoglobulin therapy resolved the exacerbations. In patients with multiphasic ADEM of unknown etiology, clinicians should also consider the possibility of preceding infection with rubella virus.

  18. Multiphase Return Trajectory Optimization Based on Hybrid Algorithm

    Directory of Open Access Journals (Sweden)

    Yi Yang

    2016-01-01

    Full Text Available A hybrid trajectory optimization method consisting of Gauss pseudospectral method (GPM and natural computation algorithm has been developed and utilized to solve multiphase return trajectory optimization problem, where a phase is defined as a subinterval in which the right-hand side of the differential equation is continuous. GPM converts the optimal control problem to a nonlinear programming problem (NLP, which helps to improve calculation accuracy and speed of natural computation algorithm. Through numerical simulations, it is found that the multiphase optimal control problem could be solved perfectly.

  19. Direct numerical simulations of gas-liquid multiphase flows

    CERN Document Server

    Tryggvason, Grétar; Zaleski, Stéphane

    2011-01-01

    Accurately predicting the behaviour of multiphase flows is a problem of immense industrial and scientific interest. Modern computers can now study the dynamics in great detail and these simulations yield unprecedented insight. This book provides a comprehensive introduction to direct numerical simulations of multiphase flows for researchers and graduate students. After a brief overview of the context and history the authors review the governing equations. A particular emphasis is placed on the 'one-fluid' formulation where a single set of equations is used to describe the entire flow field and

  20. Toughening and strengthening mechanism of zirconia-alumina multiphase ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yu, M.Q.; Fan, S.G. [Research Inst. of Synthetic Crystals, Beijing, BJ (China); Shen, Q.; Zhang, L.M. [Wuhan Univ. of Technology (China)

    2003-07-01

    In the present study, the effect of compositions on the mechanical properties of zirconia-alumina multiphase ceramics was studied. The results showed that with the variety of ZrO{sub 2} content, the change of bending strength and fracture toughness of the multiphase ceramics exhibited a saddle shape which could be divided into three zones: ZTA, ADZ, and Transition zone. The mechanism of toughening and strengthening in each zone was mainly analyzed, and it was found that stress-induced transformation toughening of ZrO{sub 2} and dispersion strengthening of Al{sub 2}O{sub 3} were the two main factors. (orig.)

  1. CFD Modeling of a Multiphase Gravity Separator Vessel

    KAUST Repository

    Narayan, Gautham

    2017-05-23

    The poster highlights a CFD study that incorporates a combined Eulerian multi-fluid multiphase and a Population Balance Model (PBM) to study the flow inside a typical multiphase gravity separator vessel (GSV) found in oil and gas industry. The simulations were performed using Ansys Fluent CFD package running on KAUST supercomputer, Shaheen. Also, a highlight of a scalability study is presented. The effect of I/O bottlenecks and using Hierarchical Data Format (HDF5) for collective and independent parallel reading of case file is presented. This work is an outcome of a research collaboration on an Aramco project on Shaheen.

  2. Development of Next Generation Multiphase Pipe Flow Prediction Tools

    Energy Technology Data Exchange (ETDEWEB)

    Cem Sarica; Holden Zhang

    2006-05-31

    The developments of oil and gas fields in deep waters (5000 ft and more) will become more common in the future. It is inevitable that production systems will operate under multiphase flow conditions (simultaneous flow of gas, oil and water possibly along with sand, hydrates, and waxes). Multiphase flow prediction tools are essential for every phase of hydrocarbon recovery from design to operation. Recovery from deep-waters poses special challenges and requires accurate multiphase flow predictive tools for several applications, including the design and diagnostics of the production systems, separation of phases in horizontal wells, and multiphase separation (topside, seabed or bottom-hole). It is crucial for any multiphase separation technique, either at topside, seabed or bottom-hole, to know inlet conditions such as flow rates, flow patterns, and volume fractions of gas, oil and water coming into the separation devices. Therefore, the development of a new generation of multiphase flow predictive tools is needed. The overall objective of the proposed study is to develop a unified model for gas-oil-water three-phase flow in wells, flow lines, and pipelines to predict flow characteristics such as flow patterns, phase distributions, and pressure gradient encountered during petroleum production at different flow conditions (pipe diameter and inclination, fluid properties and flow rates). In the current multiphase modeling approach, flow pattern and flow behavior (pressure gradient and phase fractions) prediction modeling are separated. Thus, different models based on different physics are employed, causing inaccuracies and discontinuities. Moreover, oil and water are treated as a pseudo single phase, ignoring the distinct characteristics of both oil and water, and often resulting in inaccurate design that leads to operational problems. In this study, a new model is being developed through a theoretical and experimental study employing a revolutionary approach. The

  3. Axisymmetric multiphase Lattice Boltzmann method for generic equations of state

    CERN Document Server

    Reijers, Sten A; Toschi, Federico

    2015-01-01

    We present an axisymmetric lattice Boltzmann model based on the Kupershtokh et al. multiphase model that is capable of solving liquid-gas density ratios up to $10^3$. Appropriate source terms are added to the lattice Boltzmann evolution equation to fully recover the axisymmetric multiphase conservation equations. We validate the model by showing that a stationary droplet obeys the Young-Laplace law, comparing the second oscillation mode of a droplet with respect to an analytical solution and showing correct mass conservation of a propagating density wave.

  4. Hybrid Multiphase CFD Solver for Coupled Dispersed/Segregated Flows in Liquid-Liquid Extraction

    Directory of Open Access Journals (Sweden)

    Kent E. Wardle

    2013-01-01

    Full Text Available The flows in stage-wise liquid-liquid extraction devices include both phase segregated and dispersed flow regimes. As a additional layer of complexity, for extraction equipment such as the annular centrifugal contactor, free-surface flows also play a critical role in both the mixing and separation regions of the device and cannot be neglected. Traditionally, computional fluid dynamics (CFD of multiphase systems is regime dependent—different methods are used for segregated and dispersed flows. A hybrid multiphase method based on the combination of an Eulerian multifluid solution framework (per-phase momentum equations and sharp interface capturing using Volume of Fluid (VOF on selected phase pairs has been developed using the open-source CFD toolkit OpenFOAM. Demonstration of the solver capability is presented through various examples relevant to liquid-liquid extraction device flows including three-phase, liquid-liquid-air simulations in which a sharp interface is maintained between each liquid and air, but dispersed phase modeling is used for the liquid-liquid interactions.

  5. Niacin Alternatives for Dyslipidemia: Fool's Gold or Gold Mine? Part I: Alternative Niacin Regimens.

    Science.gov (United States)

    Dunbar, Richard L; Goel, Harsh

    2016-02-01

    Niacin was the first drug demonstrating lowered cholesterol prevents coronary heart disease (CHD) events, with two clinical CHD outcome studies establishing a cardioprotective niacin regimen: 1 g thrice daily with meals. Though cardioprotective, skin toxicity limits niacin's use, fostering several variations to improve tolerability. One of these, an extended-release (ER) alternative, proved immensely successful commercially, dominating clinical practice despite departing from the established regimen in several critical ways. Hence, improved tolerability may have come at the cost of diminished efficacy, posing a conundrum: Does it still help the population at risk for CHD to broaden a drug's acceptance by "watering it down"? This question is crucial at this stage now that the ER alternative failed to recapitulate the benefits of the established cardioprotective niacin regimen in two trials of the alternative approach: AIM-HIGH and HPS2-THRIVE. Part I of this review discusses how vastly the ER alternative departs from the established cardioprotective regimen, why that is important physiologically, and how it may explain the findings of AIM-HIGH and HPS2-THRIVE. Given important gaps left by statin therapy, the established cardioprotective niacin regimen remains an important evidence-based therapy for the statin intolerant or statin averse.

  6. Investigation of hydrate formation and transportability in multiphase flow systems

    Science.gov (United States)

    Grasso, Giovanny A.

    The oil and gas industry is moving towards offshore developments in more challenging environments, where evaluating hydrate plugging risks to avoid operational/safety hazards becomes more difficult (Sloan, 2005). Even though mechanistic models for hydrate plug formation have been developed, components for a full comprehensive model are still missing. Prior to this work, research efforts were focused on flowing hydrate particles with relatively little research on hydrate accumulation, leaving hydrate deposition in multiphase flow an unexplored subject. The focus of this thesis was to better understand hydrate deposition as a form of accumu- lation in pipelines. To incorporate the multiphase flow effect, hydrate formation experiments were carried out at varying water cut (WC) from 15 to 100 vol.%, liquid loading (LL) from 50 to 85 vol.%, mixture velocity (vmix) from 0.75 to 3 m/s, for three fluids systems (100 % WC, water in Conroe crude oil emulsions and King Ranch condensate + water) on the ExxonMobil flowloop (4 in. nominal size and 314 ft. long) at Friendswood, TX. For the 100 % WC flowloop tests, hydrate particle distribution transitions beyond a critical hydrate volume concentration, observed values were between 8.2 to 29.4 vol.%, causing a sudden increase in pressure drop (DP). A revised correlation of the transition as a function of Reynolds number and liquid loading was developed. For Conroe emulsions, DP starts increasing at higher hydrate concentrations than King Ranch condensate, many times at 10 vol.%. Experiments with King Ranch show higher relative DP (10 to 25) than Conroe (2 to 10) performed at the same vmix and LL. Cohesive force measurements between cyclopentane hydrate particles were reduced from a value of 3.32 mN/m to 1.26 mN/m when 6 wt.% Conroe was used and to 0.41 mN/m when 5 wt.% Caratinga crude oil was used; similar values were obtained when extracted asphaltenes were used. King Ranch condensate (11 wt.%) did not significantly change the

  7. Profiles for voltage-activated currents are multiphasic, not curvilinear

    CERN Document Server

    Nissen, Per

    2016-01-01

    Data for voltage-activation of a potassium channel (Matulef et al. Proc Natl Acad Sci USA 110: 17886-17891. 2013) were, as conventionally done, fitted by the authors by a Boltzmann function, i.e. by a curvilinear profile. Reanalysis of the data reveals however that this interpretation must be rejected in favor of a multiphasic profile, a series of straight lines separated by discontinuous transitions, quite often in the form of noncontiguities (jumps). In contrast to the generally very poor fits to the Boltzmann profiles, the fits to multiphasic profiles are very good. (For the four replicates, the average deviations from the Boltzmann curves were 10- to 100-fold larger than the deviations from the multiphasic profiles.) The difference in the median values was statistically highly significant, P<0.001 in most cases. For the mean values the deviations from the Boltzmann curve were 20-fold larger than the deviations from the multiphasic profile, and the difference in the median values was also highly signifi...

  8. Multiphase modeling of tumor growth with matrix remodeling and fibrosis

    CERN Document Server

    Tosin, Andrea

    2009-01-01

    We present a multiphase mathematical model for tumor growth which incorporates the remodeling of the extracellular matrix and describes the formation of fibrotic tissue by tumor cells. We also detail a full qualitative analysis of the spatially homogeneous problem, and study the equilibria of the system in order to characterize the conditions under which fibrosis may occur.

  9. Analysis of hygral induced crack growth in multiphase materials

    NARCIS (Netherlands)

    Sadouki, H.; Van Mier, J.G.M.

    1996-01-01

    In this paper a numerical model for simulating crack growth processes caused by moisture movement in a porous multiphase material like concrete is proposed. In the model, the material is schematized as a regular triangular network of beam elements. The meso-material structure of the material is proj

  10. Hydrodynamical Coupling of Mass and Momentum in Multiphase Galactic Winds

    Science.gov (United States)

    Schneider, Evan E.; Robertson, Brant E.

    2017-01-01

    Using a set of high-resolution hydrodynamical simulations run with the Cholla code, we investigate how mass and momentum couple to the multiphase components of galactic winds. The simulations model the interaction between a hot wind driven by supernova explosions and a cooler, denser cloud of interstellar or circumgalactic media. By resolving scales of {{Δ }}x 100 pc distances, our calculations capture how the cloud disruption leads to a distribution of densities and temperatures in the resulting multiphase outflow and quantify the mass and momentum associated with each phase. We find that the multiphase wind contains comparable mass and momenta in phases over a wide range of densities and temperatures extending from the hot wind (n≈ {10}-2.5 {{cm}}-3, T≈ {10}6.5 K) to the coldest components (n≈ {10}2 {{cm}}-3, T≈ {10}2 K). We further find that the momentum distributes roughly in proportion to the mass in each phase, and the mass loading of the hot phase by the destruction of cold, dense material is an efficient process. These results provide new insight into the physical origin of observed multiphase galactic outflows and inform galaxy formation models that include coarser treatments of galactic winds. Our results confirm that cool gas observed in outflows at large distances from the galaxy (≳ 1 kpc) likely does not originate through the entrainment of cold material near the central starburst.

  11. Multiphase flow of immiscible fluids on unstructured moving meshes

    DEFF Research Database (Denmark)

    Misztal, Marek Krzysztof; Erleben, Kenny; Bargteil, Adam

    2012-01-01

    In this paper, we present a method for animating multiphase flow of immiscible fluids using unstructured moving meshes. Our underlying discretization is an unstructured tetrahedral mesh, the deformable simplicial complex (DSC), that moves with the flow in a Lagrangian manner. Mesh optimization op...

  12. A New Multiphase Equation of State for Composition B

    Energy Technology Data Exchange (ETDEWEB)

    Coe, Joshua Damon [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division; Margevicius, Madeline Alma [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Division

    2016-07-25

    We describe the construction of a complete equation of state for the high explosive Composition B in its unreacted (inert) form, as well as chemical equilibrium calculations of its detonation products. The multiphase reactant EOS is of SESAME type, and was calibrated to ambient thermal and mechanical data, the shock initiation experiments of Dattelbaum, et al., and the melt line of trinitrotoluene (TNT).

  13. Probabilistic events in shock driven multiphase hydrodynamic instabilities

    Science.gov (United States)

    Black, Wolfgang; Denissen, Nick; McFarland, Jacob

    2016-11-01

    Multiphase flows are an important and complex topic of research with a rich parameter space. Historically many simplifications and assumptions have been made to allow simulation techniques to be applied to these systems. Some common assumptions include no partilce-particle effects, evenly distributed particle fields, no phase change, or even constant particle radii. For some flows, these assumptions may be applicable but as the systems undergo complex accelerations and eventually become turbulent these multiphase parameters can create significant effects. Through the use of FLAG, a multiphysics hydrodynamics code developed at Los Alamos national laboratory, these assumptions can be relaxed or eliminated to increase fidelity and guide the development of experiments. This talk will build on our previous work utilizing simulations on the shock driven multiphase instability with a new investigation into a greater parameter space provided by additional multiphase effects; including a probabilistic particle field, various particle radii, and particle-particle effects on the evolution of commonly studied interfaces. Los Alamos National Laboratory LA-UR-16-25652.

  14. A single element multiphase compulsator powered railgun systems

    Energy Technology Data Exchange (ETDEWEB)

    Murthy, S.K.; Weldon, W.F. (Univ. of Texas, Austin, TX (United States). Center for Electromechanics)

    1994-01-01

    This paper investigates multiphase railguns (electromagnetic launchers) powered by multiphase compensated pulsed alternators (compulsators). The polyphase system offers several advantages over the single phase system. The multiphase compulsator relaxes the strong dependence between the current pulse width necessary for the railgun and the design parameters of the generator (number of poles, rotor diameter and tip speed) thus allowing the compulsator to be designed for optimum power density and electromechanical energy conversion. The paper examines in particular the two phase system. The authors explore different methods of achieving high acceleration ratios (average to peak) in multiphase railgun systems. Some of the methods analyzed are ramping up the field current of the compulsator to counter the increasing impedance of the gun, using a railgun with varying inductance per unit length (L[prime]), and using an external variable inductor in series with the compulsator. Special attention is devoted to the external series inductor method which uses a rotary flux compressor (rfc). Several concepts to integrate the rfc and the compulsator into a single element device are discussed. Comparison between the state of the art single phase compulsator powered 9 MJ railgun system, currently under fabrication at CEM-UT and a two phase compulsator driven four rail railgun system is also presented.

  15. Multiphase flow in a confined geometry with Dissipative Particle Dynamics

    NARCIS (Netherlands)

    Visser, D.C.

    2015-01-01

    The research presented in this thesis is focused on the modelling of multiphase flow in a confined geometry with Dissipative Particle Dynamics (DPD). DPD is a particle-based mesoscopic simulation technique that obeys the Navier-Stokes equations and is particularly useful to model complex fluids and

  16. Multiphase fluid structure interaction in bends and T-joints

    NARCIS (Netherlands)

    Cargnelutti, M.F.; Belfroid, S.P.C.; Schiferli, W.; Osch, M.M.E. van

    2010-01-01

    Air-water experiments were carried out in a horizontal 1" pipe system to measure the magnitude of the forces induced by the multiphase flow. Forces and accelerations were measured on a number of bends and T-joint configurations for a wide range of operating conditions. Five different configurations

  17. Multiphase fluid structure interaction in bends and T-joints

    NARCIS (Netherlands)

    Cargnelutti, M.F.; Belfroid, S.P.C.; Schiferli, W.; Osch, M.M.E. van

    2010-01-01

    Air-water experiments were carried out in a horizontal 1" pipe system to measure the magnitude of the forces induced by the multiphase flow. Forces and accelerations were measured on a number of bends and T-joint configurations for a wide range of operating conditions. Five different configurations

  18. Impact of sorption phenomena on multiphase conveying processes

    Science.gov (United States)

    Hatesuer, Florian; Groth, Tillmann; Reichwage, Mark; Mewes, Dieter; Luke, Andrea

    2011-08-01

    Twin-screw multiphase pumps are employed increasingly to convey multiphase mixtures of crude oil, accompanying fluids, associated gas and solid particles. They are positive displacement pumps and suitable for handling products containing liquid accompanied by large amounts of gas. Experimental investigations on the conveying characteristic, namely measuring the delivered volume flow as a function of the pressure difference, provide results for selected mixtures. By means of the on hand work, the influence of sorption phenomena occurring due to pressure variations alongside the conveying process on the conveying characteristics of twin-screw pumps delivering mixtures of oil and gases is measured. The employed gases are air and carbon dioxide, which differ strongly in solubility in oil. All experiments are conducted in a closed loop test facility, where oil and gas volume flows are mixed before the inlet and separated after the outlet of the multiphase pump. In order to simulate the influence of the suction side pressure drop in the reservoir on the conveying characteristic, packed beds are employed as oil-filed model. Sorption processes inside of the oil-field model and within the multiphase pump affect the conveying behaviour significantly. The two-phase flow in the inlet and outlet pipe is visualised by means of a capacitance tomography system. Results show that the oil fraction of the total delivered volume flow is decreased due to desorption at the pump inlet. The gas fraction at the pump outlet is further decreased due to absorption. Experimental results are compared to calculated solubilities of the on-hand gases in oil and to the theoretically derived gas volume flow fraction expected at the multiphase pump.

  19. Nanoparticle additives for multiphase systems: Synthesis, formulation and characterization

    Science.gov (United States)

    Kanniah, Vinod

    Study on nanoparticle additives in multiphase systems (liquid, polymer) are of immense interest in developing new product applications. Critical challenges for nanoparticle additives include their synthesis, formulation and characterization. These challenges are addressed in three application areas: nanofluids for engine lubrication, ultrathin nanocomposites for optical devices, and nanoparticle size distribution characterization. Nanoparticle additives in oligomer mixtures can be used to develop extended temperature range motor oils. A model system includes poly(alpha-olefin) based oligomers with a modest fraction of poly(dimethylsiloxane) oligomers along with graphite as nanoparticle additive. Partition coefficients of each oligomer are determined since the oligomer mixture phase separated at temperatures less than -15 °C. Also, the surface of graphite additive is quantitatively analyzed and modified via silanization for each oligomer. Thus, upon separation of the oligomer mixture, each functionalized graphite additive migrates to its preferred oligomers and forms a uniform dispersion. Similarly, nanoparticle additives in polymer matrices can be used to develop new low haze ultrathin film optical coatings. A model system included an acrylate monomer as the continuous phase with monodisperse or bidisperse mixtures of silica nanoparticles deposited on glass and polycarbonate substrates. Surface (root mean squared roughness, Wenzel's contact angle) and optical properties (haze) of these self assembled experimental surfaces were compared to simulated surface structures. Manipulating the size ratios of silica nanoparticle mixtures varied the average surface roughness and the height distributions, producing multimodal structures with different packing fractions. In both nanofluid and nanocomposite applications, nanoparticle additives tend to aggregate/agglomerate depending on various factors including the state of nanoparticles (powder, dispersion). A set of well

  20. Meso-scale modeling: beyond local equilibrium assumption for multiphase flow

    CERN Document Server

    Wang, Wei

    2015-01-01

    This is a summary of the article with the same title, accepted for publication in Advances in Chemical Engineering, 47: 193-277 (2015). Gas-solid fluidization is a typical nonlinear nonequilibrium system with multiscale structure. In particular, the mesoscale structure in terms of bubbles or clusters, which can be characterized by nonequilibrium features in terms of bimodal velocity distribution, energy non equipartition, and correlated density fluctuations, is the critical factor. Traditional two-fluid model (TFM) and relevant closures depend on local equilibrium and homogeneous distribution assumptions, and fail to predict the dynamic, nonequilibrium phenomena in circulating fluidized beds even with fine-grid resolution. In contrast, the mesoscale modeling, as exemplified by the energy-minimization multiscale (EMMS) model, is consistent with the nonequilibrium features in multiphase flows. Thus, the structure-dependent multi-fluid model conservation equations with the EMMS-based mesoscale modeling greatly i...

  1. Review of basal-plus insulin regimen options for simpler insulin intensification in people with Type 2 diabetes mellitus.

    Science.gov (United States)

    Raccah, D; Huet, D; Dib, A; Joseph, F; Landers, B; Escalada, J; Schmitt, H

    2017-09-01

    To identify simple insulin regimens for people with Type 2 diabetes mellitus that can be accepted and implemented earlier in primary and specialist care, taking into consideration each individual's needs and capabilities. Using randomized clinical trials identified by a search of the PubMed database, as well as systematic reviews, meta-analyses and proof-of-concept studies, this review addresses topics of interest related to the progressive intensification of a basal insulin regimen to a basal-plus regimen (one basal insulin injection plus stepwise addition of one to three preprandial short-acting insulin injections/day) vs a basal-bolus regimen (basal insulin plus three short-acting insulin injections per day) in people with Type 2 diabetes. The review explores approaches that can be used to define the meal for first prandial injection with basal-plus regimens, differences among insulin titration algorithms, and the importance of self-motivation and autonomy in achieving optimum glycaemic control. A basal-plus regimen can provide glycaemic control equivalent to that obtained with a full basal-bolus regimen, with fewer injections of prandial insulin. The first critical step is to optimize basal insulin dosing to reach a fasting glucose concentration of ~6.7 mmol/l; this allows ~40% of patients with baseline HbA1c >75 mmol/mol (9%) to be controlled with only one basal insulin injection per day. Compared with a basal-bolus regimen, a basal-plus insulin regimen is as effective but more practical, and has the best chance of acceptance and success in the real world. © 2017 The Authors. Diabetic Medicine published by John Wiley & Sons Ltd on behalf of Diabetes UK.

  2. Mesenteric panniculitis: Various presentations and treatment regimens

    Institute of Scientific and Technical Information of China (English)

    Iyad Issa; Hassan Baydoun

    2009-01-01

    Mesenteric panniculitis is a rare, benign and chronic fibrosing inflammatory disease that affects the adipose tissue of the mesentery of the small intestine and colon. The specific etiology of the disease is unknown. The diagnosis is suggested by computed tomography and is usually confirmed by surgical biopsies. Treatment is empirical and based on a few selected drugs. Surgical resection is sometimes attempted for definitive therapy, although the surgical approach is often limited. We report two cases of mesenteric panniculitis with two different presentations and subsequently varying treatment regimens. Adequate response was obtained in both patients. We present details of these cases as well as a literature review to compare various presentations, etiologies and potential treatment modalities.

  3. Qualification of CFD-models for multiphase flows

    Energy Technology Data Exchange (ETDEWEB)

    Lucas, Dirk [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany)

    2016-05-15

    While Computational Fluid Dynamics (CFD) is already an accepted industrial tool for single phase flows it is not yet mature for two-phase flows. For this reason the qualification of CFD for reactor safety relevant applications which involve multiphase flows is a present topic of research. At the CFD division of Helmholtz-Zentrum Dresden-Rossendorf (HZDR) hereby beside an application-oriented model development and validation also more generic investigations are done. Thus, the baseline model strategy aims on the consolidation of the CFD-modelling for multiphase to enable reliable predictions for well-defined flow pattern in future. In addition the recently developed GENTOP-concept broadens the range of applicability of CFD. Different flow morphologies including transitions between them can be considered in frame of this concept.

  4. Multiphase Image Segmentation Using the Deformable Simplicial Complex Method

    DEFF Research Database (Denmark)

    Dahl, Vedrana Andersen; Christiansen, Asger Nyman; Bærentzen, Jakob Andreas

    2014-01-01

    The deformable simplicial complex method is a generic method for tracking deformable interfaces. It provides explicit interface representation, topological adaptivity, and multiphase support. As such, the deformable simplicial complex method can readily be used for representing active contours in...... in image segmentation based on deformable models. We show the benefits of using the deformable simplicial complex method for image segmentation by segmenting an image into a known number of segments characterized by distinct mean pixel intensities.......The deformable simplicial complex method is a generic method for tracking deformable interfaces. It provides explicit interface representation, topological adaptivity, and multiphase support. As such, the deformable simplicial complex method can readily be used for representing active contours...

  5. Tabular Multiphase Equations of State for Metals and Their Applications

    Science.gov (United States)

    Levashov, Pavel R.; Khishchenko, Konstantin V.

    2007-12-01

    We present a method of interpolation of thermodynamic functions calculated by means of a multiphase equation of state for metals. The method takes into account melting, evaporation and sublimation phase transitions. It can be also applied in metastable regions of phase diagram including those under negative pressures. The method allows one to unambiguously determine the phase state of a given point of phase diagram. Several applications of the tabular multiphase equations of state are considered: simulation of the initial stage of electrical explosion of metal wires, formation of striations, interaction of intense laser pulses with matter etc. Information about phase state in every point of the flux allows us to study phase transition waves, apply different destruction criteria and analyze processes in metastable regions.

  6. Annihilation Radiation Gauge for Relative Density and Multiphase Fluid Monitoring

    Directory of Open Access Journals (Sweden)

    Vidal A.

    2014-03-01

    Full Text Available The knowledge of the multi-phase flow parameters are important for the petroleum industry, specifically during the transport in pipelines and network related to exploitation’s wells. Crude oil flow is studied by Monte Carlo simulation and experimentally to determine transient liquid phase in a laboratory system. Relative density and fluid phase time variation is monitored employing a fast nuclear data acquisition setup that includes two large volume BaF2 scintillator detectors coupled to an electronic chain and data display in a LabView® environment. Fluid parameters are determined by the difference in count rate of coincidence pulses. The operational characteristics of the equipment indicate that 2 % deviation in the CCR corresponds to a variation, on average, of 20 % in the fraction of liquid of the multiphase fluid.

  7. Numerical study on multiphase flows induced by wall adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Myong, Hyon Kook [Kookmin Univ., Seoul (Korea, Republic of)

    2012-07-15

    The present paper presents a numerical study on multiphase flows induced by wall adhesion. The continuum surface force (CSF) model with the wall adhesion boundary condition model is used for calculating the surface tension force; this model is implemented in an in house solution code (PowerCFD). The present method (code) employs an unstructured cell centered method based on a conservative pressure based finite volume method with a volume capturing method (CICSAM) in a volume of fluid (VOF) scheme for phase interface capturing. The effects of wall adhesion are then numerically simulated by using the present method for a shallow pool of water located at the bottom of a cylindrical tank with no external forces such as gravity. Two different cases are computed, one it which the water wets the wall and one in which the water does not wet the wall. It is found that the present method efficiently simulates the surface tension dominant multiphase flows induced by wall adhesion.

  8. Multiphase Image Segmentation Using the Deformable Simplicial Complex Method

    DEFF Research Database (Denmark)

    Dahl, Vedrana Andersen; Christiansen, Asger Nyman; Bærentzen, Jakob Andreas

    2014-01-01

    The deformable simplicial complex method is a generic method for tracking deformable interfaces. It provides explicit interface representation, topological adaptivity, and multiphase support. As such, the deformable simplicial complex method can readily be used for representing active contours...... in image segmentation based on deformable models. We show the benefits of using the deformable simplicial complex method for image segmentation by segmenting an image into a known number of segments characterized by distinct mean pixel intensities....

  9. Multiphase Flow of Immiscible Fluids on Unstructured Moving Meshes

    DEFF Research Database (Denmark)

    Misztal, Marek Krzysztof; Erleben, Kenny; Bargteil, Adam;

    2013-01-01

    In this paper, we present a method for animating multiphase flow of immiscible fluids using unstructured moving meshes. Our underlying discretization is an unstructured tetrahedral mesh, the deformable simplicial complex (DSC), that moves with the flow in a Lagrangian manner. Mesh optimization op...... complement and solve our optimization on the GPU. We provide the results of parameter studies as well as a performance analysis of our method, together with suggestions for performance optimization....

  10. Multi-Phase Galaxy Formation and Quasar Absorption Systems

    OpenAIRE

    Maller, Ariyeh H.

    2005-01-01

    The central problem of galaxy formation is understanding the cooling and condensation of gas in dark matter halos. It is now clear that to match observations this requires further physics than the simple assumptions of single phase gas cooling. A model of multi-phase cooling (Maller & Bullock 2004) can successfully account for the upper cutoff in the masses of galaxies and provides a natural explanation of many types of absorption systems (Mo & Miralda-Escude 1996). Absorption systems are our...

  11. Microstructure-based modelling of multiphase materials and complex structures

    Science.gov (United States)

    Werner, Ewald; Wesenjak, Robert; Fillafer, Alexander; Meier, Felix; Krempaszky, Christian

    2016-09-01

    Micromechanical approaches are frequently employed to monitor local and global field quantities and their evolution under varying mechanical and/or thermal loading scenarios. In this contribution, an overview on important methods is given that are currently used to gain insight into the deformational and failure behaviour of multiphase materials and complex structures. First, techniques to represent material microstructures are reviewed. It is common to either digitise images of real microstructures or generate virtual 2D or 3D microstructures using automated procedures (e.g. Voronoï tessellation) for grain generation and colouring algorithms for phase assignment. While the former method allows to capture exactly all features of the microstructure at hand with respect to its morphological and topological features, the latter method opens up the possibility for parametric studies with respect to the influence of individual microstructure features on the local and global stress and strain response. Several applications of these approaches are presented, comprising low and high strain behaviour of multiphase steels, failure and fracture behaviour of multiphase materials and the evolution of surface roughening of the aluminium top metallisation of semiconductor devices.

  12. Hydrodynamical Coupling of Mass and Momentum in Multiphase Galactic Winds

    CERN Document Server

    Schneider, Evan E

    2016-01-01

    Using a set of high resolution hydrodynamical simulations run with the Cholla code, we investigate how mass and momentum couple to the multiphase components of galactic winds. The simulations model the interaction between a hot wind driven by supernova explosions and a cooler, denser cloud of interstellar or circumgalactic media. By resolving scales of $\\Delta x 100$ pc distances our calculations capture how the cloud disruption leads to a distribution of densities and temperatures in the resulting multiphase outflow, and quantify the mass and momentum associated with each phase. We find the multiphase wind contains comparable mass and momenta in phases over a wide range of densities extending from the hot wind $(n \\approx 10^{-3}$ $\\mathrm{cm}^{-3})$ to the coldest components $(n \\approx 10^2$ $\\mathrm{cm}^{-3})$. We further find that the momentum distributes roughly in proportion to the mass in each phase, and the mass-loading of the hot phase by the destruction of cold, dense material is an efficient proc...

  13. Numerical modeling of a compressible multiphase flow through a nozzle

    Science.gov (United States)

    Niedzielska, Urszula; Rabinovitch, Jason; Blanquart, Guillaume

    2012-11-01

    New thermodynamic cycles developed for more efficient low temperature resource utilization can increase the net power production from geothermal resources and sensible waste heat recovery by 20-40%, compared to the traditional organic Rankine cycle. These improved systems consist of a pump, a liquid heat exchanger, a two-phase turbine, and a condenser. The two-phase turbine is used to extract energy from a high speed multiphase fluid and consists of a nozzle and an axial impulse rotor. In order to model and optimize the fluid flow through this part of the system an analysis of two-phase flow through a specially designed convergent-divergent nozzle has to be conducted. To characterize the flow behavior, a quasi-one-dimensional steady-state model of the multiphase fluid flow through a nozzle has been constructed. A numerical code capturing dense compressible multiphase flow under subsonic and supersonic conditions and the coupling between both liquid and gas phases has been developed. The output of the code delivers data vital for the performance optimization of the two-phase nozzle.

  14. Mixing and reactions in multiphase flow through porous media

    Science.gov (United States)

    Jimenez-Martinez, J.; Le Borgne, T.; Meheust, Y.; Porter, M. L.; De Anna, P.; Hyman, J.; Tabuteau, H.; Turuban, R.; Carey, J. W.; Viswanathan, H. S.

    2016-12-01

    The understanding and quantification of flow and transport processes in multiphase systems remains a grand scientific and engineering challenge in natural and industrial systems (e.g., soils and vadose zone, CO2 sequestration, unconventional oil and gas extraction, enhanced oil recovery). Beyond the kinetic of the chemical reactions, mixing processes in porous media play a key role in controlling both fluid-fluid and fluid-solid reactions. However, conventional continuum-scale models and theories oversimplify and/or ignore many important pore-scale processes. Multiphase flows, with the creation of highly heterogeneous fluid velocity fields (i.e., low velocities regions or stagnation zones, and high velocity regions or preferential paths), makes conservative and reactive transport more complex. We present recent multi-scale experimental developments and theoretical approaches to quantify transport, mixing, and reaction and their coupling with multiphase flows. We discuss our main findings: i) the sustained concentration gradients and enhanced reactivity in a two-phase system for a continuous injection, and the comparison with a pulse line injection; ii) the enhanced mixing by a third mobile-immiscible phase; and iii) the role that capillary forces play in the localization of the fluid-solid reactions. These experimental results are for highly-idealized geometries, however, the proposed models are related to basic porous media and unsaturated flow properties, and could be tested on more complex systems.

  15. Enhanced Light Scattering of Secondary Organic Aerosols by Multiphase Reactions.

    Science.gov (United States)

    Li, Kun; Li, Junling; Liggio, John; Wang, Weigang; Ge, Maofa; Liu, Qifan; Guo, Yucong; Tong, Shengrui; Li, Jiangjun; Peng, Chao; Jing, Bo; Wang, Dong; Fu, Pingqing

    2017-02-07

    Secondary organic aerosol (SOA) plays a pivotal role in visibility and radiative forcing, both of which are intrinsically linked to the refractive index (RI). While previous studies have focused on the RI of SOA from traditional formation processes, the effect of multiphase reactions on the RI has not been considered. Here, we investigate the effects of multiphase processes on the RI and light-extinction of m-xylene-derived SOA, a common type of anthropogenic SOA. We find that multiphase reactions in the presence of liquid water lead to the formation of oligomers from intermediate products such as glyoxal and methylglyoxal, resulting in a large enhancement in the RI and light-scattering of this SOA. These reactions will result in increases in light-scattering efficiency and direct radiative forcing of approximately 20%-90%. These findings improve our understanding of SOA optical properties and have significant implications for evaluating the impacts of SOA on the rapid formation of regional haze, global radiative balance, and climate change.

  16. Modeling hyperelasticity in non-equilibrium multiphase flows

    Science.gov (United States)

    Hank, Sarah; Favrie, Nicolas; Massoni, Jacques

    2017-02-01

    The aim of this article is the construction of a multiphase hyperelastic model. The Eulerian formulation of the hyperelasticity represents a system of 14 conservative partial differential equations submitted to stationary differential constraints. This model is constructed with an elegant approach where the specific energy is given in separable form. The system admits 14 eigenvalues with 7 characteristic eigenfields. The associated Riemann problem is not easy to solve because of the presence of 7 waves. The shear waves are very diffusive when dealing with the full system. In this paper, we use a splitting approach to solve the whole system using 3 sub-systems. This method reduces the diffusion of the shear waves while allowing to use a classical approximate Riemann solver. The multiphase model is obtained by adapting the discrete equations method. This approach involves an additional equation governing the evolution of a phase function relative to the presence of a phase in a cell. The system is integrated over a multiphase volume control. Finally, each phase admits its own equations system composed of three sub-systems. One and three dimensional test cases are presented.

  17. Shock Initiated Reactions of Reactive Multiphase Blast Explosives

    Science.gov (United States)

    Wilson, Dennis; Granier, John; Johnson, Richard; Littrell, Donald

    2015-06-01

    This paper describes a new class of reactive multiphase blast explosives (RMBX) and characterization of their blast characteristics. These RMBXs are non-ideal explosive compositions of perfluoropolyether (PFPE), nano aluminum, and a micron-size high-density reactive metal - Tantalum, Zirconium, or Zinc in mass loadings of 66 to 83 percent. Unlike high explosives, these PFPE-metal compositions release energy via a fast self-oxidized combustion wave (rather than a true self-sustaining detonation) that is shock dependent, and can be overdriven to control energy release rate. The term ``reactive multiphase blast'' refers to the post-dispersion blast behavior: multiphase in that there are a gas phase that imparts pressure and a solid (particulate) phase that imparts momentum; and reactive in that the hot metal particles react with atmospheric oxygen and the explosive gas products to give an extended pressure pulse. The RMBX formulations were tested in two spherical core-shell geometries - an RMBX shell exploded by a high explosive core, and an RMBX core imploded by a high explosive shell. The fireball and blast characteristics were compared to a C-4 baseline charge.

  18. Multiphase feeding program for broilers can replace traditional system

    Directory of Open Access Journals (Sweden)

    Luciano Hauschild

    2015-06-01

    Full Text Available Broilers are traditionally managed with feeding programs that often consist of three or four phases. In this study we investigated whether a multiphase feeding program (14 phases of broilers based on the optimal mix of two feeds could replace a traditional four phase system while maintaining broiler performance. To evaluate this prposed program we measured variables of performance, carcass yield, and nitrogen excretion. In addition, we determined if the multiphase feeding program (14 phases would be equally effective regardless of bird gender. A total of 480 day-old Cobb chicks were used, with an average weight of 44.74 ± 0.16 g (females and 44.71 ± 0.11 g (males. The birds were distributed in a completely randomized 2 × 2 factorial design. Each treatment consisted of six replicates with 20 animals per experimental unit. Results were analyzed separately in two periods (1–21 and 22–42 days as determined by slaughter date, as well as for the entire growth period (1–42 days. The multiphase program led to improvements in final body weight and average daily weight gain, in addition to an increase in breast yield.

  19. Melt processed multiphase ceramic waste forms for nuclear waste immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Amoroso, Jake, E-mail: jake.amoroso@srs.gov [Savannah River National Laboratory, Aiken, SC 29808 (United States); Marra, James C. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Tang, Ming [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lin, Ye; Chen, Fanglin [University of South Carolina, Columbia, SC 29208 (United States); Su, Dong [Brookhaven National Laboratory, Upton, NY 11973 (United States); Brinkman, Kyle S. [Clemson University, Clemson, SC 29634 (United States)

    2014-11-15

    Highlights: • We explored the feasibility of melt processing multiphase titanate-based ceramics. • Melt processing produced phases obtained by alternative processing methods. • Phases incorporated multiple lanthanides and transition metals. • Processing in reducing atmosphere suppressed un-desirable Cs–Mo coupling. • Cr partitions to and stabilizes the hollandite phase, which promotes Cs retention. - Abstract: Ceramic waste forms are promising hosts for nuclear waste immobilization as they have the potential for increased durability and waste loading compared with conventional borosilicate glass waste forms. Ceramics are generally processed using hot pressing, spark plasma sintering, and conventional solid-state reaction, however such methods can be prohibitively expensive or impractical at production scales. Recently, melt processing has been investigated as an alternative to solid-state sintering methods. Given that melter technology is currently in use for High Level Waste (HLW) vitrification in several countries, the technology readiness of melt processing appears to be advantageous over sintering methods. This work reports the development of candidate multi-phase ceramic compositions processed from a melt. Cr additions, developed to promote the formation and stability of a Cs containing hollandite phase were successfully incorporated into melt processed multi-phase ceramics. Control of the reduction–oxidation (Redox) conditions suppressed undesirable Cs–Mo containing phases, and additions of Al and Fe reduced the melting temperature.

  20. A Virtual Reality Technique for Multi-phase Flows

    Science.gov (United States)

    Loth, Eric; Sherman, William; Auman, Aric; Navarro, Christopher

    2004-04-01

    A virtual reality (VR) technique has been developed to allow user immersion (stereo-graphic rendering, user tracking and object interactivity) in generic unsteady three-dimensional multi-phase flow data sets. This article describes the structure and logic used to design and construct a VR technique that employs a multi-phase flow-field computed a priori as an input (i.e. simulations are conducted beforehand with a researcher's multi-phase CFD code). The input field for this flow visualization is divided into two parts: the Eulerian three-dimensional grid nodes and velocities for the continuous fluid properties (specified using conventional TECLOT data format) and the Lagrangian time-history trajectory files for the dispersed fluid. While tracking the dispersed phase trajectories as animated spheres of adjustable size and number, the continuous-phase flow can be simultaneously rendered with velocity vectors, iso-contour surfaces and planar flood-contour maps of different variables. The geometric and notional view of the combined visualization of both phases is interactively controlled throughout a user session. The resulting technique is demonstrated with a 3-D unsteady data set of Lagrangian particles dispersing in a Eulerian description of a turbulent boundary layer, stemming from a direct numerical simulation of the Navier-Stokes equations.

  1. Numerical simulation of complex multi-phase fluid of casting process and its applications

    Institute of Scientific and Technical Information of China (English)

    CHEN Li-liang; LIU Rui-xiang; C. Beckermann

    2006-01-01

    The fluid of casting process is a typical kind of multi-phase flow. Actually, many casting phenomena have close relationship with the multi-phase flow, such as molten metal filling process, air entrapment, slag movement, venting process of die casting, gas escaping of lost foam casting and so on. Obviously, in order to analyze these phenomena accurately,numerical simulation of the multi-phase fluid is necessary. Unfortunately, so far, most of the commercial casting simulation systems do not have the ability of multi-phase flow modeling due to the difficulty in the multi-phase flow calculation. In the paper, Finite Different Method (FDM) technique was adopt to solve the multi-phase fluid model. And a simple object of the muiti-phase fluid was analyzed to obtain the fluid rates of the liquid phase and the entrapped air phase.

  2. Numerical simulation of complex multi-phase fluid of casting process and its applications

    Directory of Open Access Journals (Sweden)

    CHEN Li-liang

    2006-05-01

    Full Text Available The fluid of casting process is a typical kind of multi-phase flow. Actually, many casting phenomena have close relationship with the multi-phase flow, such as molten metal filling process, air entrapment, slag movement, venting process of die casting, gas escaping of lost foam casting and so on. Obviously, in order to analyze these phenomena accurately, numerical simulation of the multi-phase fluid is necessary. Unfortunately, so far, most of the commercial casting simulation systems do not have the ability of multi-phase flow modeling due to the difficulty in the multi-phase flow calculation. In the paper, Finite Different Method (FDM technique was adopt to solve the multi-phase fluid model. And a simple object of the muiti-phase fluid was analyzed to obtain the fluid rates of the liquid phase and the entrapped air phase.

  3. Numerical modeling of geophysical granular flows: 1. A comprehensive approach to granular rheologies and geophysical multiphase flows

    Science.gov (United States)

    Dartevelle, SéBastien

    2004-08-01

    Geophysical granular materials display a wide variety of behaviors and features. Typically, granular flows (1) are multiphase flows, (2) are very dissipative over many different scales, (3) display a wide range of grain concentrations, and (4), as a final result of these previous features, display complex nonlinear, nonuniform, and unsteady rheologies. Therefore the objectives of this manuscript are twofold: (1) setting up a hydrodynamic model which acknowledges the multiphase nature of granular flows and (2) defining a comprehensive rheological model which accounts for all the different forms of viscous dissipations within granular flows at any concentration. Hence three important regimes within granular flows must be acknowledged: kinetic (pure free flights of grain), kinetic-collisional, and frictional. The momentum and energy transfer will be different according to the granular regimes, i.e., strain rate dependent in the kinetic and kinetic-collisional cases and strain rate independent in the frictional case. A "universal" granular rheological model requires a comprehensive unified stress tensor able to adequately describe viscous stress within the flow for any of these regimes, and without imposing a priori what regime will dominate over the others. The kinetic-collisional viscous regime is defined from a modified Boltzmann's kinetic theory of dense gas. The frictional viscous regime is defined from the plastic potential and the critical state theories which account for compressibility of granular matter (e.g., dilatancy, consolidation, and critical state). In the companion paper [, 2004] we will introduce a multiphase computer code, (G)MFIX, which accounts for all the granular regimes and rheology and present typical simulations of diluted (e.g., plinian clouds) and concentrated geophysical granular flows (i.e., pyroclastic flows and surges).

  4. Quantifying Supernovae-driven Multiphase Galactic Outflows

    Science.gov (United States)

    Li, Miao; Bryan, Greg L.; Ostriker, Jeremiah P.

    2017-06-01

    Galactic outflows are observed everywhere in star-forming disk galaxies and are critical for galaxy formation. Supernovae (SNe) play the key role in driving the outflows, but there is no consensus as to how much energy, mass, and metal they can launch out of the disk. We perform 3D, high-resolution hydrodynamic simulations to study SNe-driven outflows from stratified media. Assuming the SN rate scales with gas surface density Σgas as in the Kennicutt-Schmidt relation, we find that the mass loading factor, η m, defined as the mass outflow flux divided by the star formation surface density, decreases with increasing Σgas as {η }{{m}}\\propto {{{Σ }}}{gas}-0.61. Approximately Σgas ≲ 50 M ⊙ pc-2 marks when η m ≳ 1. About 10%-50% of the energy and 40%-80% of the metals produced by SNe end up in the outflows. The tenuous hot phase (T > 3 × 105 K), which fills 60%-80% of the volume at the midplane, carries the majority of the energy and metals in the outflows. We discuss how various physical processes, including the vertical distribution of SNe, photoelectric heating, external gravitational field, and SN rate, affect the loading efficiencies. The relative scale height of gas and SNe is a very important factor in determining the loading efficiencies.

  5. Quantifying Supernovae-Driven Multiphase Galactic Outflows

    CERN Document Server

    Li, Miao; Ostriker, Jeremiah P

    2016-01-01

    Galactic outflows are ubiquitously observed in star-forming disk galaxies and are critical for galaxy formation. Supernovae (SNe) play the key role in driving the outflows, but there is no consensus as to how much energy, mass and metal they can launch out of the disk. We perform 3D, high-resolution hydrodynamic simulations to study SNe-driven outflows from stratified media. Assuming SN rate scales with gas surface density $\\Sigma_{\\rm{gas}}$ as in the Kennicutt-Schmidt (KS) relation, we find the mass loading factor, defined as the mass outflow flux divided by the star formation surface density, decreases with increasing $\\Sigma_{\\rm{gas}}$ as $\\propto \\Sigma^{-0.61}_{\\rm{gas}}$. Approximately $\\Sigma_{\\rm{gas}} \\lesssim$ 50 $M_\\odot/pc^2$ marks when the mass loading factor $\\gtrsim$1. About 10-50\\% of the energy and 40-80\\% of the metals produced by SNe end up in the outflows. The tenuous hot phase ($T>3\\times 10^5$ K) carries the majority of the energy and metals in outflows. We discuss how various physical...

  6. The impact resistance of Kevlar woven fabrics impregnated with highly concentrated multiphase suspensions

    Institute of Scientific and Technical Information of China (English)

    Liu Jun; Xiong Dangsheng

    2016-01-01

    The stab and puncture resistance of Kevlar woven fabrics impregnated with different kinds of highly concentrated multiphase suspensions was studied with self-made dual-catheter drop-hammer tester. The results showed that the shear thickening of multiphase particles was possibly based on hydrocluster and particle jamming mechanism; the introduction of alumina silicate fibre can remarkably improve the composite spike resistance, and multiphase particles co-strengthening can provide best protection effect; otherwise, the stab resistance increases weakly.

  7. Comparative analysis of volumetric flow meters used for mass flow estimation in multiphase and multidensity environments

    Science.gov (United States)

    Pedone, Richard; Korman, Valentin; Wiley, John T.

    2006-05-01

    Accurate and reliable multiphase flow measurements are needed for liquid propulsion systems. Existing volumetric flow meters are adequate for flow measurements with well-characterized, clean liquids and gases. However, these technologies are inadequate for multiphase environments, such as cryogenic fluids. Although, properly calibrated turbine flow meters can provide highly accurate and repeatable data, problems are still prevalent with multiphase flows. Limitations are thus placed on the applicability of intrusive turbine flow meters.

  8. Stress-Induced Phase Transformation in Incompressible Materials and Stability of Multi-Phase Deformation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The stress-induced phase transformation in incompressible materials and the interfacial stability of multi-phase deformation were studied. The existence of multi-phase deformation was determined through exploring whether the material would lose the strong ellipticity at some deformation gradient.Then, according to the stability criterion which is based on a quasi-static approach, the stability of the multi-phase deformation in incompressible materials was investigated by studying the growth/decay behaviour of the interface in the undeformed configuration when it is perturbed. At last, the way to define multi-phase deformation in incompressible materials was concluded and testified by a corresponding numerical example.

  9. The Sex Res Non Naturales and the Regimen of Health

    DEFF Research Database (Denmark)

    Agerholm, Frank Juul

    2013-01-01

    The paper discusses the ethical and social soundness of the classical idea of diaita/regimen vis-à-vis the contemporary focus on healthy lifestyle......The paper discusses the ethical and social soundness of the classical idea of diaita/regimen vis-à-vis the contemporary focus on healthy lifestyle...

  10. Experimental determination of the speciation, partitioning, and release of perrhenate as a chemical surrogate for pertechnetate from a sodalite-bearing multiphase ceramic waste form

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, Eric M.; Lukens, Wayne W.; Fitts, Jeff. P.; Jantzen, Carol. M.; Tang, G.

    2013-12-01

    A key component to closing the nuclear fuel cycle is the storage and disposition of nuclear waste in geologic systems. Multiphase ceramic waste forms have been studied extensively as a potential host matrix for nuclear waste. Understanding the speciation, partitioning, and release behavior of radionuclides immobilized in multiphase ceramic waste forms is a critical aspect of developing the scientific and technical basis for nuclear waste management. In this study, we evaluated a sodalite-bearing multiphase ceramic waste form (i.e., fluidized-bed steam reform sodium aluminosilicate [FBSR NAS] product) as a potential host matrix for long-lived radionuclides, such as technetium (99Tc). The FBSR NAS material consists primarily of nepheline (ideally NaAlSiO4), anion-bearing sodalites (ideally M8[Al6Si6O24]X2, where M refers to alkali and alkaline earth cations and X refers to monovalent anions), and nosean (ideally Na8[AlSiO4]6SO4). Bulk X-ray absorption fine structure analysis of the multiphase ceramic waste form, suggest rhenium (Re) is in the Re(VII) oxidation state and has partitioned to a Re-bearing sodalite phase (most likely a perrhenate sodalite Na8[Al6Si6O24](ReO4)2). Rhenium was added as a chemical surrogate for 99Tc during the FBSR NAS synthesis process. The weathering behavior of the FBSR NAS material was evaluated under hydraulically unsaturated conditions with deionized water at 90 ?C. The steady-state Al, Na, and Si concentrations suggests the weathering mechanisms are consistent with what has been observed for other aluminosilicate minerals and include a combination of ion exchange, network hydrolysis, and the formation of an enriched-silica surface layer or phase. The steady-state S and Re concentrations are within an order of magnitude of the nosean and perrhenate sodalite solubility, respectively. The order of magnitude difference between the observed and predicted concentration for Re and S may be associated with the fact that the anion

  11. Experimental Determination of the Speciation, Partitioning, and Release of Perrhenate as a Chemical Surrogate for Pertechnetate from a Sodalite-Bearing Multiphase Ceramic Waste Form

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, Eric M [ORNL; Lukens, Wayne W [Lawrence Berkeley National Laboratory (LBNL); Fitts, Jeffrey P [Princeton University; Tang, Guoping [ORNL; Jantzen, C M [Savannah River National Laboratory (SRNL)

    2013-01-01

    A key component to closing the nuclear fuel cycle is the storage and disposition of nuclear waste in geologic systems. Multiphase ceramic waste forms have been studied extensively as a potential host matrix for nuclear waste. Understanding the speciation, partitioning, and release behavior of radionuclides immobilized in multiphase ceramic waste forms is a critical aspect of developing the scientific and technical basis for nuclear waste management. In this study, we evaluated a sodalite-bearing multiphase ceramic waste form (i.e., fluidized-bed steam reform sodium aluminosilicate [FBSR NAS] product) as a potential host matrix for long-lived radionuclides, such as technetium (99Tc). The FBSR NAS material consists primarily of nepheline (ideally NaAlSiO4), anion-bearing sodalites (ideally M8[Al6Si6O24]X2, where M refers to alkali and alkaline earth cations and X refers to monovalent anions), and nosean (ideally Na8[AlSiO4]6SO4). Bulk x-ray absorption fine structure analysis of the multiphase ceramic waste form, suggest rhenium (Re) is in the Re(VII) oxidation state and has partitioned to a Re-bearing sodalite phase (most likely a perrhenate sodalite Na8[Al6Si6O24](ReO4)2). Rhenium was added as a chemical surrogate for 99Tc during the FBSR NAS synthesis process. The weathering behavior of the FBSR NAS material was evaluated under hydraulically unsaturated conditions with deionized water at 90 C. The steady-state Al, Na, and Si concentrations suggests the weathering mechanisms are consistent with what has been observed for other aluminosilicate minerals and include a combination of ion exchange, network hydrolysis, and the formation of an enriched-silica surface layer or phase. The steady-state S and Re concentrations are within an order of magnitude of the nosean and perrhenate sodalite solubility, respectively. The order of magnitude difference between the observed and predicted concentration for Re and S may be associated with the fact that the anion

  12. Adherence to asthma controller medication regimens.

    Science.gov (United States)

    Stempel, D A; Stoloff, S W; Carranza Rosenzweig, J R; Stanford, R H; Ryskina, K L; Legorreta, A P

    2005-10-01

    Improved adherence to inhaled corticosteroids (ICS) is recognized as an important factor in reduced morbidity, mortality and consumption of health care resources. The present study was designed to replicate previous reports of patient adherence with fluticasone/salmeterol in a single inhaler (FSC), fluticasone and salmeterol in separate inhalers (FP+SAL), fluticasone and montelukast (FP+MON), fluticasone alone (FP) and montelukast alone (MON). A 24-month observational retrospective study was conducted using administrative claims data. Subjects were 12 years old with 24 months of continuous enrollment; had 1 asthma claim (ICD-9: 493), 1 short-acting beta(2)-agonist claim, and 1 FSC, FP, SAL, or MON claim. Outcomes included asthma medication refill rates and persistence measured by treatment days. This study was designed with a unique population of patients with asthma from different health plans to validate previous findings. A total of 3,503 subjects were identified based on their index medication: FSC (996), FP+SAL (259), FP+MON (101), FP (1254) and MON (893). Mean number of prescription refills for FSC (3.98) was significantly higher than FP (2.29) and the FP component of FP+SAL (2.36), and FP+MON (2.15), P<0.05. No significant differences were observed between FSC and MON fill rates (4.33). Mean number of treatment days was greater for FSC compared to FP, FP+SAL, and FP+MON (P<0.0001). This study confirms a previous report that adherence profiles of fluticasone and salmeterol in a single inhaler are significantly better when compared to the controller regimens of fluticasone and salmeterol in separate inhalers, fluticasone and montelukast, or fluticasone alone and similar to montelukast alone.

  13. Noninvasive tomographic and velocimetric monitoring of multiphase flows

    Energy Technology Data Exchange (ETDEWEB)

    Chaouki, J. [Ecole Polytechnique de Montreal, Quebec (Canada). Dept. of Chemical Engineering; Larachi, F. [Laval Univ., Quebec (Canada); Dudukovic, M.P. [Washington Univ., St. Louis, MO (United States). Chemical Reaction Engineering Lab.

    1997-11-01

    A condensed review of recent advances accomplished in the development and the applications of noninvasive tomographic and velocimetric measurement techniques to multiphase flows and systems is presented. In recent years utilization of such noninvasive techniques has become widespread in many engineering disciplines that deal with systems involving two immiscible phases or more. Tomography provides concentration, holdup, or 2D or 3D density distribution of at least one component of the multiphase system, whereas velocimetry provides the dynamic features of the phase of interest such as the flow pattern, the velocity field, the 2D or 3D instantaneous movements, etc. The following review is divided into two parts. The first part summarizes progress and developments in flow imaging techniques using {gamma}-ray and X-ray transmission tomography; X-ray radiography; neutron transmission tomography and radiography; positron emission tomography; X-ray diffraction tomography; nuclear magnetic resonance imaging; electrical capacitance tomography; optical tomography; microwave tomography; and ultrasonic tomography. The second part of the review summarizes progress and developments in the following velocimetry techniques: positron emission particle tracking; radioactive particle tracking; cinematography; laser-Doppler anemometry; particle image velocimetry; and fluorescence particle image velocimetry. The basic principles of tomography and velocimetry techniques are outlined, along with advantages and limitations inherent to each technique. The hydrodynamic and structural information yielded by these techniques is illustrated through a literature survey on their successful applications to the study of multiphase systems in such fields as particulate solids processes, fluidization engineering, porous media, pipe flows, transport within packed beds and sparged reactors, etc.

  14. Multiphase modeling of geologic carbon sequestration in saline aquifers.

    Science.gov (United States)

    Bandilla, Karl W; Celia, Michael A; Birkholzer, Jens T; Cihan, Abdullah; Leister, Evan C

    2015-01-01

    Geologic carbon sequestration (GCS) is being considered as a climate change mitigation option in many future energy scenarios. Mathematical modeling is routinely used to predict subsurface CO2 and resident brine migration for the design of injection operations, to demonstrate the permanence of CO2 storage, and to show that other subsurface resources will not be degraded. Many processes impact the migration of CO2 and brine, including multiphase flow dynamics, geochemistry, and geomechanics, along with the spatial distribution of parameters such as porosity and permeability. In this article, we review a set of multiphase modeling approaches with different levels of conceptual complexity that have been used to model GCS. Model complexity ranges from coupled multiprocess models to simplified vertical equilibrium (VE) models and macroscopic invasion percolation models. The goal of this article is to give a framework of conceptual model complexity, and to show the types of modeling approaches that have been used to address specific GCS questions. Application of the modeling approaches is shown using five ongoing or proposed CO2 injection sites. For the selected sites, the majority of GCS models follow a simplified multiphase approach, especially for questions related to injection and local-scale heterogeneity. Coupled multiprocess models are only applied in one case where geomechanics have a strong impact on the flow. Owing to their computational efficiency, VE models tend to be applied at large scales. A macroscopic invasion percolation approach was used to predict the CO2 migration at one site to examine details of CO2 migration under the caprock.

  15. Multiphase simulation of mine waters and aqueous leaching processes

    Directory of Open Access Journals (Sweden)

    Pajarre Risto

    2016-01-01

    Full Text Available Managing of large amounts of water in mining and mineral processing sites remains a concern in both actively operated and closed mining areas. When the mining site with its metal or concentrate producing units is operational, the challenge is to find either ways for economical processing with maximum yields, while minimizing the environmental impact of the water usage and waste salt treatments. For safe closure of the site, the environmental control of possible drainage will be needed. For both challenges, the present-day multiphase process simulations tools can be used to provide improved accuracy and better economy in controlling the smooth and environmentally sound operation of the plant. One of the pioneering studies in using the multiphase thermodynamic software in simulation of hydrometallurgical processes was that of Koukkari et al. [1]. The study covered the use of Solgasmix equilibrium software for a number of practical acid digesters. The models were made for sulfuric acid treatments in titania pigment production and in NPK fertilizer manufacturing. During the past two decades the extensive data assessment has taken place particularly in geochemistry and a new versions of geochemical multiphase equilibrium software has been developed. On the other hand, there has been some progress in development of the process simulation software in all the aforementioned fields. Thus, the thermodynamic simulation has become a tool of great importance in development of hydrometallurgical processes. The presentation will cover three example cases of either true pilot or industrial systems including a South African acid mine water drainage treatment, hydrometallurgical extraction of rare earths from uranium leachate in Russia and a multistage process simulation of a Finnish heap leaching mine with its subsequent water treatment system.

  16. Among once-daily regimens, single tablet regimens (STRs are associated with better adherence

    Directory of Open Access Journals (Sweden)

    R Murri

    2012-11-01

    Full Text Available Previous published evidences showed that taking HAART once-daily (OD is associated to better adherence when compared to BID or TID regimens. However, no further studies investigated whether, among OD regimens, adherence levels can be differently influenced. Aim of the study was to evaluate levels of self-reported adherence in HIV+ people according to type of HAART dosing (STR, OD with more than one pill or BID. To limit reporting biases, the study was performed in five different non-clinic settings covering North and Central Italy. A total of 230 patients on stable HAART were asked to complete a semi-structured, anonymous questionnaire reporting their attitude toward HAART, their adherence and the acceptability of their regimen. Self-perception of adherence was also investigated with a single item for comparison with real adherence behavior. Most of the subjects were males (66% with a mean age of 46 years, with higher education level (72% and a long history of HIV infection (mean 13.6 years. 17% of patients were on a first-line regimen. 21% reported to miss at least one dose during the past week (STR: 6%; OD >1 pill 23% and BID 21%; p<0.05. People taking STR and BID tend to report less discontinuations (all the drug of the day for at least 3 times in a month compared to OD>1 pill (6 and 4% vs 11%. People taking therapies other than HAART reported similar adherence levels of people taking only HAART, even when stratified for dosing groups. Even people judging their adherence as ‘optimal’ or ‘very good’, 10 and 17% respectively, reported having missed a dose during the last week. At stepwise regression model, optimal adherence was correlated to being male (OR: 2.38; 95% CI: 1.19–4.74, younger (OR: 3.04; 95% CI: 1.01–9.13 and with a shorter HIV infection (OR: 3.58; 95% CI: 1.04–12.38. People taking simpler once-daily STR tend to report better adherence than people taking OD>1 pill or BID. Perception of optimal adherence is largely

  17. Slush Fund: Modeling the Multiphase Physics of Oceanic Ices

    Science.gov (United States)

    Buffo, J.; Schmidt, B. E.

    2016-12-01

    The prevalence of ice interacting with an ocean, both on Earth and throughout the solar system, and its crucial role as the mediator of exchange between the hydrosphere below and atmosphere above, have made quantifying the thermodynamic, chemical, and physical properties of the ice highly desirable. While direct observations of these quantities exist, their scarcity increases with the difficulty of obtainment; the basal surfaces of terrestrial ice shelves remain largely unexplored and the icy interiors of moons like Europa and Enceladus have never been directly observed. Our understanding of these entities thus relies on numerical simulation, and the efficacy of their incorporation into larger systems models is dependent on the accuracy of these initial simulations. One characteristic of seawater, likely shared by the oceans of icy moons, is that it is a solution. As such, when it is frozen a majority of the solute is rejected from the forming ice, concentrating in interstitial pockets and channels, producing a two-component reactive porous media known as a mushy layer. The multiphase nature of this layer affects the evolution and dynamics of the overlying ice mass. Additionally ice can form in the water column and accrete onto the basal surface of these ice masses via buoyancy driven sedimentation as frazil or platelet ice. Numerical models hoping to accurately represent ice-ocean interactions should include the multiphase behavior of these two phenomena. While models of sea ice have begun to incorporate multiphase physics into their capabilities, no models of ice shelves/shells explicitly account for the two-phase behavior of the ice-ocean interface. Here we present a 1D multiphase model of floating oceanic ice that includes parameterizations of both density driven advection within the `mushy layer' and buoyancy driven sedimentation. The model is validated against contemporary sea ice models and observational data. Environmental stresses such as supercooling and

  18. Applications of turbulent and multi-phase combustion

    CERN Document Server

    Kuo, Kenneth Kuan-yun

    2012-01-01

    A hands-on, integrated approach to solving combustion problems in diverse areas An understanding of turbulence, combustion, and multiphase reacting flows is essential for engineers and scientists in many industries, including power genera-tion, jet and rocket propulsion, pollution control, fire prevention and safety, and material processing. This book offers a highly practical discussion of burning behavior and chemical processes occurring in diverse materials, arming readers with the tools they need to solve the most complex combustion problems facing the scientific community today. The

  19. Texture and microstructure of the austenite in multiphased steel sheets

    Energy Technology Data Exchange (ETDEWEB)

    Regle, H. [ARCELOR Group, CMC-IRSID, Maizieres-les-Metz (France); Maruyama, N.; Yoshinaga, N. [Nippon Steel Corp. - Technical Development Bureau, Futtsu (Japan)

    2004-07-01

    In this paper we present results obtained in collaboration between NSC and Arcelor on the austenite of a multiphased steel and on a 70%Ni-30Fe alloy. The work concerns the formation of the crystallographic textures during the recrystallisation of austenite, since these textures have a strong influence, after the phase transformation, on the forming properties of the sheets. The microstructure and the textures of the austenite and the FeNi alloy were measured with X-Ray diffraction techniques and with EBSD on a high resolution FEG-SEM. (orig.)

  20. Modeling of Multiscale and Multiphase Phenomena in Materials Processing

    Science.gov (United States)

    Ludwig, Andreas; Kharicha, Abdellah; Wu, Menghuai

    2013-03-01

    In order to demonstrate how CFD can help scientists and engineers to better understand the fundamentals of engineering processes, a number of examples are shown and discussed. The paper covers (i) special aspects of continuous casting of steel including turbulence, motion and entrapment of non-metallic inclusions, and impact of soft reduction; (ii) multiple flow phenomena and multiscale aspects during casting of large ingots including flow-induced columnar-to-equiaxed transition and 3D formation of channel segregation; (iii) multiphase magneto-hydrodynamics during electro-slag remelting; and (iv) melt flow and solidification of thin but large centrifugal castings.

  1. The development of the Minnesota Multiphasic Personality Inventory.

    Science.gov (United States)

    Buchanan, R D

    1994-04-01

    The Minnesota Multiphasic Personality Inventory (MMPI) was constructed at the University of Minnesota before and during World War II. In its developmental phase, the MMPI was conceptualized as an efficient way of detecting psychiatric disturbance. The test's construction was made possible by atypical cooperation between psychologists and psychiatrists, within the context of a crisis in the U.S. public mental health care system. The MMPI was designed to meet the diagnostic needs of psychiatrists. As such, it represented the operationalization of medical hegemony. However, the interpretation of the MMPI shifted significantly after the war, reflecting organizational reform in clinical psychology and changing professional relationships between psychologists and psychiatrists.

  2. WD-XRA technique in multiphase flow measuring

    Energy Technology Data Exchange (ETDEWEB)

    Gogolev, A.S.; Cherepennikov, Yu.M.; Vukolov, A.V. [Tomsk Polytechnic University, Lenin Avenue 30, Tomsk 634050 (Russian Federation); Rezaev, R.O. [Tomsk Polytechnic University, Lenin Avenue 30, Tomsk 634050 (Russian Federation); Nuclear University MEPhI, Kashirskoye Shosse 31, Moscow 115409 (Russian Federation); Stuchebrov, S.G. [Tomsk Polytechnic University, Lenin Avenue 30, Tomsk 634050 (Russian Federation); Hampai, D. [INFN Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); Dabagov, S.B. [INFN Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy); Nuclear University MEPhI, Kashirskoye Shosse 31, Moscow 115409 (Russian Federation); RAS P.N. Lebedev Physical Institute, Lenin Avenue 53, Moscow 119991 (Russian Federation); Liedl, A.; Polese, C. [INFN Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044 Frascati (Italy)

    2015-07-15

    A new technique to perform the analysis of multiphase fluid flow based on wave dispersive X-ray absorptiometry is suggested. The numerical simulation and comparison of this technique with currently used approaches are provided and a way to increase the luminosity intensity is found that includes the usage the X-ray focusing optics by a bent crystal and a polycapillary semilens. Based on numerical simulation of radiation spectrum the influence of the bent crystal on the luminosity is evaluated and experimentally shown the advantages of using the multicapillary optics.

  3. WD-XRA technique in multiphase flow measuring

    Science.gov (United States)

    Gogolev, A. S.; Cherepennikov, Yu. M.; Vukolov, A. V.; Rezaev, R. O.; Stuchebrov, S. G.; Hampai, D.; Dabagov, S. B.; Liedl, A.; Polese, C.

    2015-07-01

    A new technique to perform the analysis of multiphase fluid flow based on wave dispersive X-ray absorptiometry is suggested. The numerical simulation and comparison of this technique with currently used approaches are provided and a way to increase the luminosity intensity is found that includes the usage the X-ray focusing optics by a bent crystal and a polycapillary semilens. Based on numerical simulation of radiation spectrum the influence of the bent crystal on the luminosity is evaluated and experimentally shown the advantages of using the multicapillary optics.

  4. Multiphase flow of immiscible fluids on unstructured moving meshes

    DEFF Research Database (Denmark)

    Misztal, Marek Krzysztof; Erleben, Kenny; Bargteil, Adam;

    2012-01-01

    In this paper, we present a method for animating multiphase flow of immiscible fluids using unstructured moving meshes. Our underlying discretization is an unstructured tetrahedral mesh, the deformable simplicial complex (DSC), that moves with the flow in a Lagrangian manner. Mesh optimization...... that the underlying discretization matches the physics and avoids the additional book-keeping required in grid-based methods where multiple fluids may occupy the same cell. Our Lagrangian approach naturally leads us to adopt a finite element approach to simulation, in contrast to the finite volume approaches adopted...

  5. Numerical modeling of multiphase flow in rough and propped fractures

    Science.gov (United States)

    Dabrowski, Marcin; Dzikowski, Michał; Jasinski, Lukasz; Olkiewicz, Piotr

    2017-04-01

    crystalline rocks. The detailed pattern of flow paths and effective fracture conductivity are largely dependent on the level of confining stresses and fracture wall roughness, which both determine the shape and distribution of fracture apertures and contact areas. The distribution of proppant grains, which are used to maintain apertures of hydraulic fractures, is a key factor governing fracture flow in industrial applications. The flow of multiphase fluids in narrow apertures of rock fractures may substantially differ from the flow of a single-phase fluid. For example, multiphase flow effects play an important role during all stages of unconventional reservoir life cycle. Multiphase flow conditions are also expected to prevail in high temperature geothermal fields and during the transport of non aqueous phase liquid contaminants in groundwaters. We use direct numerical simulations to study single- and multiphase flow in rough and propped fractures. We compute the fluid flow using either the finite element or the lattice Boltzmann method. Body-fitting, unstructured computational meshes are used to improve the numerical accuracy. The fluid-fluid and fluid-solid interfaces are directly resolved and an implicit approach to surface tension is used to alleviate restrictions due to capillary CFL condition. In FEM simulations, the Beltrami-Laplace operator is integrated by parts to avoid interface curvature computation during evaluation of the surface tension term. We derive and validate an upscaled approach to Stokes flow in propped and rough fractures. Our upscaled 2.5D fracture flow model features a Brinkman term and is capable of treating no-slip boundary conditions on the rims of proppant grains and fracture wall contact areas. The Stokes-Brinkman fracture flow model provides an improvement over the Reynolds model, both in terms of the effective fracture permeability and the local flow pattern. We present numerical and analytical models for the propped fracture

  6. MULTIPHASE BLASTING OF THE BRIDGE ACROSS THE DRENICA RIVER

    Directory of Open Access Journals (Sweden)

    Branko Božić

    1989-12-01

    Full Text Available The construction of new bridges on the sites of the existing ones require demolition of the old bridge. Due to closeness of newly erected bridge elements the fundations of old bridges are demolished by multiphase blasting process. The blasting of the piers and anchorages of the bridge across 'the Drenica river carrying the Balačevac—Goleš industrial railway was done in four phases. The piers and anchorages of a new bridge and its construction elements have been erected before (the paper is published in Croatian.

  7. A new multiphase equation of state for iron

    Energy Technology Data Exchange (ETDEWEB)

    Kerley, G.I.

    1993-07-01

    The PANDA code was used to develop an equation of state (EOS) for iron. Separate EOS tables were constructed for four solid phases and the fluid phase. The phase diagram and multiphase EOS table were then computed using the free energies. Results are in good agreement with thermophysical, static compression, phase boundary, and shock-wave measurements. Predicted pressures for the shock-induced {epsilon}-{gamma} and {gamma}-liquid transitions agree with those determined from sound speed measurements. Predicted melting temperatures fall in between two recent sets of experimental data which sharply disagree with one another.

  8. Nonlinear analysis and prediction of time series in multiphase reactors

    CERN Document Server

    Liu, Mingyan

    2014-01-01

    This book reports on important nonlinear aspects or deterministic chaos issues in the systems of multi-phase reactors. The reactors treated in the book include gas-liquid bubble columns, gas-liquid-solid fluidized beds and gas-liquid-solid magnetized fluidized beds. The authors take pressure fluctuations in the bubble columns  as time series for nonlinear analysis, modeling and forecasting. They present qualitative and quantitative non-linear analysis tools which include attractor phase plane plot, correlation dimension, Kolmogorov entropy and largest Lyapunov exponent calculations and local non-linear short-term prediction.

  9. Separation of Nanoparticles in Aqueous Multiphase Systems through Centrifugation

    KAUST Repository

    Akbulut, Ozge

    2012-08-08

    This paper demonstrates the use of aqueous multiphase systems (MuPSs) as media for rate-zonal centrifugation to separate nanoparticles of different shapes and sizes. The properties of MuPSs do not change with time or during centrifugation; this stability facilitates sample collection after separation. A three-phase system demonstrates the separation of the reaction products (nanorods, nanospheres, and large particles) of a synthesis of gold nanorods, and enriches the nanorods from 48 to 99% in less than ten minutes using a benchtop centrifuge. © 2012 American Chemical Society.

  10. Vertical flow of a multiphase mixture in a channel

    Directory of Open Access Journals (Sweden)

    Mehrdad Massoudi

    2001-01-01

    Full Text Available The flow of a multiphase mixture consisting of a viscous fluid and solid particles between two vertical plates is studied. The theory of interacting continua or mixture theory is used. Constitutive relations for the stress tensor of the granular materials and the interaction force are presented and discussed. The flow of interest is an ideal one where we assume the flow to be steady and fully developed; the mixture is flowing between two long vertical plates. The non-linear boundary value problem is solved numerically, and the results are presented for the dimensionless velocity profiles and the volume fraction as functions of various dimensionless numbers.

  11. STUDY OF EFFICACY OF LOW DOSE MAGNESIUM SULPHATE REGIMEN (DHAKA REGIMEN AS COMPARED TO STANDARD REGIMEN (PRITCHARD IN THE MANAGEMENT OF ECLAMPSIA

    Directory of Open Access Journals (Sweden)

    Prosun

    2015-07-01

    Full Text Available BACKGROUND : Eclampsia is one of the most important cause of maternal mortality and morbidity worldwide Dr . J . A . Pritchard in 1955 , introduced magnesium sulphate for control of convulsions in eclampsia and now magnesium sulfate is the anticonvulsant drug of choice for both prevention and treatment of eclampsia , but due to its narrow therapeutic window its dose - related toxicity is a major concern . Considering the lower body weight of Indian women than wes tern counter part , different low dose magnesium sulphate regime has been formulated in different parts of India and Bangladesh and these modifications appeared to reduce drug toxicity . The Objective was to compare the efficacy of low dose magnesium sulphat e regimen ( Dhaka regimen with standard Pritchard’s regimen for management of eclampsia . METHODS: This was a hospital based prospective study conducted in the Dept . of O & G of VSSMCH , Burla from Oct . 2012 to S ept . 2014 . Total 300 patients with eclampsia were included in study and randomly distributed into two groups containing 150 patients each in both Dhaka & Pritchard groups . The statistical software SPSS version 20 has been used for the analysis . An alpha error of 5% has been taken as significant . RESU LTS: In the present study , there is no recurrence of convulsion among both the groups . The Dhaka regimen was associated with significantly lower deep tendon reflex loss ( 2 . 67% vs 8 . 0%; P =0 . 040 , significantly lower total amount of Mgso4 requirement , and lower maternal mortality ( 3 . 33% vs 6 . 67%; P = 0 . 185 as compared with the standerd Pritchard regimen . CONCLUSIONS : The maternal morbidity and mortality in the present study were comparable to those of standard Pritchard’s regimen . The Dhaka regimen was equ ally effective and more safe for the management of eclampsia in a region where most women are of low body weight KEYWORDS: Antepartum E clampsia ; Magnesium S ulphate; Dhaka R egimen; Pritchard R

  12. Flip-Flops for accurate multiphase clocking: transmission gate versus current mode logic

    NARCIS (Netherlands)

    Dutta, R.; Klumperink, Eric A.M.; Gao, X.; Ru, Z.; van der Zee, Ronan A.R.; Nauta, Bram

    2013-01-01

    Dynamic transmission gate (DTG) flip-flops (FFs) (DTG-FFs) and current mode logic (CML) FFs (CML-FFs) are compared targeting power efficient multiphase clock generation with low phase error. The effect of component mismatches on multiphase clock timing inaccuracies is modeled and compared, using the

  13. Multiphase flow in lab on chip devices: A real tool for the future

    NARCIS (Netherlands)

    Shui, Lingling; Pennathur, S.; Pennathur, Sumita; Eijkel, Jan C.T.; van den Berg, Albert

    2008-01-01

    Many applications for lab on a chip (LOC) devices require the use of two or more fluids that are either not chemically related (e.g. oil and water) or in different phases (e.g. liquid and gas). Utilizing multiphase flow in LOC devices allows for both the fundamental study of multiphase flow and the

  14. Multiphase forces on bend structures – overview of large scale 6”experiments

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Nennie, E.D.; Wijhe, A. van; Pereboom, H.P.; Lewis, M.

    2016-01-01

    Piping structures are generally subjected to high dynamic loading due to multiphase forces. In particular subsea structures are very vulnerable as large flexibility is required to cope for instance with thermal stresses. The forces due to multiphase flow are characterized by a broadband spectrum wit

  15. Measuring Bubble, Drop and Particle Sizes in Multiphase Systems with Ultrasound

    NARCIS (Netherlands)

    Cents, A.H.G.; Brilman, D.W.F.; Versteeg, G.F.; Wijnstra, P.J.; Regtien, P.P.L.

    2004-01-01

    A technique is developed for measurement of bubble, droplet and particle-size distributions in multiphase systems, based on the propagation speed and attenuation of ultrasound. The measurement of the size distribution of the dispersed phase in multiphase systems was desired to analyze the mass-trans

  16. Downhole multiphase metering in wells by means of soft-sensing

    NARCIS (Netherlands)

    Leskens, M.; Kruif, B. de; Belfroid, S.P.C.; Smeulers, J.P.M.; Gryzlov, A.

    2008-01-01

    Multiphase flow meters are indispensable tools for achieving optimal operation and control of wells as these meters deliver real-time information about their performance. For example, multiphase flow meters located downhole can improve the production of multilateral and multizone wells by timely all

  17. Multiphase flow in microfluidic systems - Control and applications of droplets and interfaces

    NARCIS (Netherlands)

    Shui, Lingling; Eijkel, Jan C.T.; Berg, van den Albert

    2007-01-01

    Micro- and nanotechnology can provide us with many tools for the production, study and detection of colloidal and interfacial systems. In multiphase flow in micro- and nanochannels several immiscible fluids will be separated from each other by flexible fluidic interfaces. The multiphase coexistence

  18. Multiphase forces on bend structures – overview of large scale 6”experiments

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Nennie, E.D.; Wijhe, A. van; Pereboom, H.P.; Lewis, M.

    2016-01-01

    Piping structures are generally subjected to high dynamic loading due to multiphase forces. In particular subsea structures are very vulnerable as large flexibility is required to cope for instance with thermal stresses. The forces due to multiphase flow are characterized by a broadband spectrum wit

  19. Flip-Flops for accurate multiphase clocking: transmission gate versus current mode logic

    NARCIS (Netherlands)

    Dutta, R.; Klumperink, E.A.M.; Gao, X.; Ru, Z.; Zee, van der R.A.R.; Nauta, B.

    2013-01-01

    Dynamic transmission gate (DTG) flip-flops (FFs) (DTG-FFs) and current mode logic (CML) FFs (CML-FFs) are compared targeting power efficient multiphase clock generation with low phase error. The effect of component mismatches on multiphase clock timing inaccuracies is modeled and compared, using the

  20. Hybrid Therapy Regimen for Helicobacter Pylori Eradication

    Institute of Scientific and Technical Information of China (English)

    Zhi-Qiang Song; Jian Liu; Li-Ya Zhou

    2016-01-01

    Objective:Helicobacterpylori (H.pylori) eradication remains a challenge with increasing antibiotic resistance.Hybrid therapy has attracted widespread attention because of initial report with good efficacy and safety.However,many issues on hybrid therapy are still unclear such as the eradication efficacy,safety,compliance,influencing factors,correlation with antibiotic resistance,and comparison with other regimens.Therefore,a comprehensive review on the evidence of hybrid therapy for H.pylori infection was conducted.Data Sources:The data used in this review were mainly from PubMed articles published in English up to September 30,2015,searching by the terms of"Helicobacterpylori" or "H.pylori",and "hybrid".Study Selection:Clinical research articles were selected mainly according to their level of relevance to this topic.Results:Totally,1871 patients of 12 studies received hybrid therapy.The eradication rates were 77.6-97.4% in intention-to-treat and 82.6-99.1% in per-protocol analyses.Compliance was 93.3-100.0%,overall adverse effects rate was 14.5-67.5%,and discontinued medication rate due to adverse effects was 0-6.7%.H.pylori culture and sensitivity test were performed only in 13.3% patients.Pooled analysis showed that the eradication rates with dual clarithromycin and metronidazole susceptible,isolated metronidazole or clarithromycin resistance,and dual clarithromycin and metronidazole resistance were 98.5%,97.6%,92.9%,and 80.0%,respectively.Overall,the efficacy,compliance,and safety of hybrid therapy were similar with sequential or concomitant therapy.However,hybrid therapy might be superior to sequential therapy in Asians.Conclusions:Hybrid therapy showed wide differences in the efficacy but consistently good compliance and safety across different regions.Dual clarithromycin and metronidazole resistance were the key factor to efficacy.Hybrid therapy was similar to sequential or concomitant therapy in the efficacy,safety,and compliance.

  1. Interface effects on multiphase flows in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Duan Z [Los Alamos National Laboratory

    2008-01-01

    Most models for multiphase flows in a porous medium are based on the straightforward extension of Darcy's law, in which each fluid phase is driven by its own pressure gradient. The pressure difference between the phases is thought to be an effect of surface tension and is called capillary pressure. Independent of Darcy's law, for liquid imbibition processes in a porous material, diffusion models are sometime used. In this paper, an ensemble phase averaging technique for continuous multi phase flows is applied to derive averaged equations and to examine the validity of the commonly used models. The closure for the averaged equations is quite complicated for general multiphase flows in a porous material. For flows with a small ratio of the characteristic length of the phase interfaces to the macroscopic length, the closure relations can be simplified significantly by an approximation with a second order error in the length ratio. The approximation reveals the information of the length scale separation obscured during the ensemble averaging process, and leads to an equation system similar to Darcy's law, but with additional terms. Based on interactions on phase interfaces, relations among closure quantities are studied.

  2. Black hole feedback in a multiphase interstellar medium

    Science.gov (United States)

    Bourne, Martin A.; Nayakshin, Sergei; Hobbs, Alexander

    2014-07-01

    Ultrafast outflows (UFOs) from supermassive black holes (SMBHs) are thought to regulate the growth of SMBHs and host galaxies, resulting in a number of observational correlations. We present high-resolution numerical simulations of the impact of a thermalized UFO on the ambient gas in the inner part of the host galaxy. Our results depend strongly on whether the gas is homogeneous or clumpy. In the former case all of the ambient gas is driven outward rapidly as expected based on commonly used energy budget arguments, while in the latter the flows of mass and energy de-couple. Carrying most of the energy, the shocked UFO escapes from the bulge via paths of least resistance, taking with it only the low-density phase of the host. Most of the mass is however in the high-density phase, and is affected by the UFO much less strongly, and may even continue to flow inwards. We suggest that the UFO energy leakage through the pores in the multiphase interstellar medium (ISM) may explain why observed SMBHs are so massive despite their overwhelmingly large energy production rates. The multiphase ISM effects reported here are probably under-resolved in cosmological simulations but may be included in prescriptions for active galactic nuclei feedback in future simulations and in semi-analytical models.

  3. Direct Numerical Simulation of Multiphase Flows with Unstable Interfaces

    Science.gov (United States)

    Schillaci, Eugenio; Lehmkuhl, Oriol; Antepara, Oscar; Oliva, Assensi

    2016-09-01

    This paper presents a numerical model that intends to simulate efficiently the surface instability that arise in multiphase flows, typically liquid-gas, both for laminar or turbulent regimes. The model is developed on the in-house computing platform TermoFluids, and operates the finite-volume, direct numerical simulation (DNS) of multiphase flows by means of a conservative level-set method for the interface-capturing. The mesh size is optimized by means of an adaptive mesh refinement (AMR) strategy, that allows the dynamic re-concentration of the mesh in the vicinity of the interfaces between fluids, in order to correctly represent the diverse structures (as ligaments and droplets) that may rise from unstable phenomena. In addition, special attention is given to the discretization of the various terms of the momentum equations, to ensure stability of the flow and correct representation of turbulent vortices. As shown, the method is capable of truthfully simulate the interface phenomena as the Kelvin-Helmholtz instability and the Plateau-Rayleigh instability, both in the case of 2-D and 3-D configurations. Therefore it is suitable for the simulation of complex phenomena such as simulation of air-blast atomization, with several important application in the field of automotive and aerospace engines. A prove is given by our preliminary study of the 3-D coaxial liquid-gas jet.

  4. Multi-phase multi-component reactive flow in Geodynamics

    Science.gov (United States)

    Oliveira, Beñat; Afonso, Juan Carlos; Zlotnik, Sergio

    2016-04-01

    Multi-phase multi-component reactive flow (MPMCRF) controls a number of important complex geodynamic/geochemical problems, such as melt generation and percolation, metasomatism, rheological weakening, magmatic differentiation, ore emplacement, and fractionation of chemical elements, to name a few. These interacting processes occur over very different spatial and temporal scales and under very different physico-chemical conditions. Therefore, there is a strong motivation in geodynamics for investigating the equations governing MPMCRF, their mathematical structure and properties, and the numerical techniques necessary to obtain reliable and accurate results. In this contribution we present results from a novel numerical framework to solve multiscale MPMCRF problems in geodynamic contexts. Our approach is based on the effective tracking of the most basic building blocks: internal energy and chemical composition. This is achieved through the combination of rigorous solutions to the conservation equations (mass, energy and momentum) for each dynamic phase (instead of the more common "mixture-type" approach) and the transport equation for the chemical species, within the context of classical irreversible thermodynamics. Interfacial processes such as phase changes, chemical diffusion+reaction, and surface tension effects are explicitly incorporated in the context of ensemble averaging. Phase assemblages, mineral and melt compositions, and all other physical parameters of multi-phase systems are obtained through dynamic free-energy minimization procedures.

  5. Radiation damage of hollandite in multiphase ceramic waste forms

    Science.gov (United States)

    Clark, Braeden M.; Tumurgoti, Priyatham; Sundaram, S. K.; Amoroso, Jake W.; Marra, James C.; Shutthanandan, Vaithiyalingam; Tang, Ming

    2017-10-01

    Radiation damage was simulated in multiphase titanate-based ceramic waste forms using an ion accelerator to generate high energy alpha particles (He+) and an ion implanter to generate 7 MeV gold (Au3+) particles. X-ray diffraction and transmission electron microscopy were used to characterize the damaged surfaces and nearby regions. Simulated multiphase ceramic waste forms were prepared using two processing methods: spark plasma sintering and melt-processing. Both processing methods produced ceramics with similar phase assemblages consisting of hollandite-, zirconolite/pyrochlore-, and perovskite-type phases. The measured heavy ion (Au3+) penetration depth was less in spark plasma sintered samples than in melt-processed samples. Structural breakdown of the hollandite phase occurred under He+ irradiation indicated by the presence of x-ray diffraction peaks belonging to TiO2, BaTiO5, and other hollandite related phases (Ba2Ti9O20). The composition of the constituent hollandite phase affected the extent of damage induced by Au3+ ions.

  6. Stability Analysis of Reactive Multiphase Slug Flows in Microchannels

    Directory of Open Access Journals (Sweden)

    Alejandro A. Munera Parra

    2014-05-01

    Full Text Available Conducting multiphase reactions in micro-reactors is a promising strategy for intensifying chemical and biochemical processes. A major unresolved challenge is to exploit the considerable benefits offered by micro-scale operation for industrial scale throughputs by numbering-up whilst retaining the underlying advantageous flow characteristics of the single channel system in multiple parallel channels. Fabrication and installation tolerances in the individual micro-channels result in different pressure losses and, thus, a fluid maldistribution. In this work, an additional source of maldistribution, namely the flow multiplicities, which can arise in a multiphase reactive or extractive flow in otherwise identical micro-channels, was investigated. A detailed experimental and theoretical analysis of the flow stability with and without reaction for both gas-liquid and liquid-liquid slug flow has been developed. The model has been validated using the extraction of acetic acid from n-heptane with the ionic liquid 1-Ethyl-3-methylimidazolium ethyl sulfate. The results clearly demonstrate that the coupling between flow structure, the extent of reaction/extraction and pressure drop can result in multiple operating states, thus, necessitating an active measurement and control concept to ensure uniform behavior and optimal performance.

  7. Elastic registration of multiphase CT images of liver

    Science.gov (United States)

    Heldmann, Stefan; Zidowitz, Stephan

    2009-02-01

    In this work we present a novel approach for elastic image registration of multi-phase contrast enhanced CT images of liver. A problem in registration of multiphase CT is that the images contain similar but complementary structures. In our application each image shows a different part of the vessel system, e.g., portal/hepatic venous/arterial, or biliary vessels. Portal, arterial and biliary vessels run in parallel and abut on each other forming the so called portal triad, while hepatic veins run independent. Naive registration will tend to align complementary vessel. Our new approach is based on minimizing a cost function consisting of a distance measure and a regularizer. For the distance we use the recently proposed normalized gradient field measure that focuses on the alignment of edges. For the regularizer we use the linear elastic potential. The key feature of our approach is an additional penalty term using segmentations of the different vessel systems in the images to avoid overlaps of complementary structures. We successfully demonstrate our new method by real data examples.

  8. IMAGES ACQUISITION OF MULTIPHASE DISPERSIONS IN FERMENTATION PROCESSES

    Directory of Open Access Journals (Sweden)

    T. Brito

    2003-04-01

    Full Text Available Multiphase mixing is a common operation in fermentation process. However, one of the main problems for onlineautomatic monitoring of dispersions occurring in microbial cultures in a mechanically stirred bioreactor, isthe difficulty in acquiring images (in motion clear enough to characterize its elements (mainly air, water, oiland biomass and their interactions during cultivation. Once the images to be analyzed have been acquired,other problems arise related to the complexity and diversity of objects/artifacts captured in the visual field. Theheterogeneous transparency of some objects, low contrast and similarity between different classes of objectsare, among others, major problems for the automation of image analysis procedures. The purpose of thiswork is to present a system that allows the on-line acquisition of images inside a mechanically stirred tank.The images are digitally obtained by connecting a TV camera to a stereomicroscope. The scanning of thecamera is synchronized to the flashing of a stroboscope, which acts as the light source and is equipped with asubmergible probe. These illumination conditions allow obtaining high quality images that can be furtheranalyzed to quantify size distributions of air bubbles and oil drops in multiphase dispersion, and to observe thedynamics of phase interactions (solid, liquid and gaseous in a model culture.

  9. Shock initiated reactions of reactive multi-phase blast explosives

    Science.gov (United States)

    Wilson, Dennis; Granier, John; Johnson, Richard; Littrell, Donald

    2017-01-01

    This paper describes a new class of non-ideal explosive compositions made of perfluoropolyether (PFPE), nanoaluminum, and a micron-size, high mass density, reactive metal. Unlike high explosives, these compositions release energy via a fast self-oxidized combustion wave rather than a true self-sustaining detonation. Their reaction rates are shock dependent and they can be overdriven to change their energy release rate. These compositions are fuel rich and have an extended aerobic energy release phase. The term "reactive multiphase blast" refers to the post-dispersion blast behavior: multiphase in that there are a gas phase that imparts pressure and a solid (particulate) phase that imparts energy and momentum [1]; and reactive in that the hot metal particles react with atmospheric oxygen and the explosive gas products to give an extended pressure pulse. Tantalum-based RMBX formulations were tested in two spherical core-shell configurations - an RMBX shell exploded by a high explosive core, and an RMBX core imploded by a high explosive shell. The fireball and blast characteristics were compared to a C-4 baseline charge.

  10. Melt processed multiphase ceramic waste forms for nuclear waste immobilization

    Science.gov (United States)

    Amoroso, Jake; Marra, James C.; Tang, Ming; Lin, Ye; Chen, Fanglin; Su, Dong; Brinkman, Kyle S.

    2014-11-01

    Ceramic waste forms are promising hosts for nuclear waste immobilization as they have the potential for increased durability and waste loading compared with conventional borosilicate glass waste forms. Ceramics are generally processed using hot pressing, spark plasma sintering, and conventional solid-state reaction, however such methods can be prohibitively expensive or impractical at production scales. Recently, melt processing has been investigated as an alternative to solid-state sintering methods. Given that melter technology is currently in use for High Level Waste (HLW) vitrification in several countries, the technology readiness of melt processing appears to be advantageous over sintering methods. This work reports the development of candidate multi-phase ceramic compositions processed from a melt. Cr additions, developed to promote the formation and stability of a Cs containing hollandite phase were successfully incorporated into melt processed multi-phase ceramics. Control of the reduction-oxidation (Redox) conditions suppressed undesirable Cs-Mo containing phases, and additions of Al and Fe reduced the melting temperature.

  11. Multiphase flows in complex geometries: a UQ perspective

    KAUST Repository

    Icardi, Matteo

    2015-01-07

    Nowadays computer simulations are widely used in many multiphase flow applications involving interphases, dispersed particles, and complex geometries. Most of these problems are solved with mixed models composed of fundamental physical laws, rigorous mathematical upscaling, and empirical correlations/closures. This means that classical inference techniques or forward parametric studies, for example, becomes computationally prohibitive and must take into account the physical meaning and constraints of the equations. However mathematical techniques commonly used in Uncertainty Quantification can come to the aid for the (i) modeling, (ii) simulation, and (iii) validation steps. Two relevant applications for environmental, petroleum, and chemical engineering will be presented to highlight these aspects and the importance of bridging the gaps between engineering applications, computational physics and mathematical methods. The first example is related to the mathematical modeling of sub-grid/sub-scale information with Probability Density Function (PDF) models in problems involving flow, mixing, and reaction in random environment. After a short overview of the research field, some connections and similarities with Polynomial Chaos techniques, will be investigated. In the second example, averaged correlations laws and effective parameters for multiphase flow and their statistical fluctuations, will be considered and efficient computational techniques, borrowed from high-dimensional stochastic PDE problems, will be applied. In presence of interfacial flow, where small spatial scales and fast time scales are neglected, the assessment of robustness and predictive capabilities are studied. These illustrative examples are inspired by common problems arising, for example, from the modeling and simulation of turbulent and porous media flows.

  12. Failure Mode and Effect Analysis of Subsea Multiphase Pump Equipment

    Directory of Open Access Journals (Sweden)

    Oluwatoyin Shobowale Kafayat

    2014-07-01

    Full Text Available Finding oil and gas reserves in deep/harsh environment with challenging reservoir and field conditions, subsea multiphase pumping benefits has found its way to provide solutions to these issues. Challenges such as failure issues that are still surging the industry and with the current practice of information hiding, this issues becomes even more difficult to tackle. Although, there are some joint industry projects which are only accessible to its members, still there is a need to have a clear understanding of these equipment groups so as to know which issues to focus attention on. A failure mode and effect analysis (FMEA is a potential first aid in understanding this equipment groups. A survey questionnaire/interview was conducted with the oil and gas operating company and equipment manufacturer based on the literature review. The results indicates that these equipment’s group are similar with its onshore counterpart, but the difference is the robustness built into the equipment internal subsystems for subsea applications. The results from the manufacturer perspectives indicates that Helico-axial multiphase pump have a mean time to failure of more than 10 years, twin-screw and electrical submersible pumps are still struggling with a mean time to failure of less than 5 years.

  13. Impact Detection for Characterization of Complex Multiphase Flows

    Science.gov (United States)

    Chan, Wai Hong Ronald; Urzay, Javier; Mani, Ali; Moin, Parviz

    2016-11-01

    Multiphase flows often involve a wide range of impact events, such as liquid droplets impinging on a liquid pool or gas bubbles coalescing in a liquid medium. These events contribute to a myriad of large-scale phenomena, including breaking waves on ocean surfaces. As impacts between surfaces necessarily occur at isolated points, numerical simulations of impact events will require the resolution of molecular scales near the impact points for accurate modeling. This can be prohibitively expensive unless subgrid impact and breakup models are formulated to capture the effects of the interactions. The first step in a large-eddy simulation (LES) based computational methodology for complex multiphase flows like air-sea interactions requires effective detection of these impact events. The starting point of this work is a collision detection algorithm for structured grids on a coupled level set / volume of fluid (CLSVOF) solver adapted from an earlier algorithm for cloth animations that triangulates the interface with the marching cubes method. We explore the extension of collision detection to a geometric VOF solver and to unstructured grids. Supported by ONR/A*STAR. Agency of Science, Technology and Research, Singapore; Office of Naval Research, USA.

  14. Development of Next Generation Multiphase Pipe Flow Prediction Tools

    Energy Technology Data Exchange (ETDEWEB)

    Tulsa Fluid Flow

    2008-08-31

    The developments of fields in deep waters (5000 ft and more) is a common occurrence. It is inevitable that production systems will operate under multiphase flow conditions (simultaneous flow of gas-oil-and water possibly along with sand, hydrates, and waxes). Multiphase flow prediction tools are essential for every phase of the hydrocarbon recovery from design to operation. The recovery from deep-waters poses special challenges and requires accurate multiphase flow predictive tools for several applications including the design and diagnostics of the production systems, separation of phases in horizontal wells, and multiphase separation (topside, seabed or bottom-hole). It is very crucial to any multiphase separation technique that is employed either at topside, seabed or bottom-hole to know inlet conditions such as the flow rates, flow patterns, and volume fractions of gas, oil and water coming into the separation devices. The overall objective was to develop a unified model for gas-oil-water three-phase flow in wells, flow lines, and pipelines to predict the flow characteristics such as flow patterns, phase distributions, and pressure gradient encountered during petroleum production at different flow conditions (pipe diameter and inclination, fluid properties and flow rates). The project was conducted in two periods. In Period 1 (four years), gas-oil-water flow in pipes were investigated to understand the fundamental physical mechanisms describing the interaction between the gas-oil-water phases under flowing conditions, and a unified model was developed utilizing a novel modeling approach. A gas-oil-water pipe flow database including field and laboratory data was formed in Period 2 (one year). The database was utilized in model performance demonstration. Period 1 primarily consisted of the development of a unified model and software to predict the gas-oil-water flow, and experimental studies of the gas-oil-water project, including flow behavior description and

  15. Controlled-protein dietary regimens for Parkinson's disease.

    Science.gov (United States)

    Cereda, Emanuele; Barichella, Michela; Pezzoli, Gianni

    2010-02-01

    Continuous levodopa replacement still is the most efficacious treatment for patients with Parkinson's disease. Unfortunately, the neutral aromatic amino acids contained in dietary proteins may compete with this drug for intestinal absorption and transport across the blood-brain barrier, thus limiting its efficacy and being responsible for the occurrence of motor fluctuations. Current guidelines recommend low-protein dietary regimens with protein redistribution, as shifting protein intake to the evening has proved to ameliorate the response to levodopa. However, adherence to this dietary regimen does not seem to be satisfactory and response is variable. Recent studies have shown that low-protein products designed for chronic renal failure patients are safe, tasty, well-tolerated and useful in improving both adherence to low-protein dietary regimens and levodopa-related motor fluctuations. However, there still is the need to define the selection criteria for the patients who may benefit the most from adherence to this regimen.

  16. Chemotherapy Regimen Extends Survival in Advanced Pancreatic Cancer Patients

    Science.gov (United States)

    A four-drug chemotherapy regimen has produced the longest improvement in survival ever seen in a phase III clinical trial of patients with metastatic pancreatic cancer, one of the deadliest types of cancer.

  17. What to Start: Selecting a First HIV Regimen

    Science.gov (United States)

    HIV Treatment What to Start: Choosing an HIV Regimen (Last updated 2/24/2016; last reviewed 2/24/ ... of HIV medicines used to treat HIV infection. HIV treatment (also called antiretroviral therapy or ART) begins with ...

  18. Single-tablet regimens (STRs enhance patients’ acceptability of HAART

    Directory of Open Access Journals (Sweden)

    F Maggiolo

    2012-11-01

    Full Text Available Patients’ acceptability of HAART is a subjective variable that may deeply influence therapeutic outcome. The feeling of the patient may alter adherence and lead to virologic failure. Acceptability may depend on various variables often difficulty evaluated by the care-giver. In a clinical setting the evaluation of acceptability is difficult, too, as patients may feel a judgement and be less sincere. Aim of this study was to asses adherence and acceptability of HAART. To limit reporting biases, the study was performed in five different non-clinic settings covering North and Central Italy. A total of 230 patients on stable HAART were asked to complete a semi-structured, anonymous questionnaire reporting their attitude toward HAART, their adherence and the acceptability of their regimen. In these notes we focus on this last patient-oriented outcome. Most of the subjects were males (66% with a mean age of 46 years, with higher education level (72% and a long history of HIV infection (mean 13.6 years. Consequently only 17% of patients were on a first-line regimen. Patients reporting a high or very high acceptability of HAART were 60% compared to a 31% reporting a fair grade of satisfaction and a 9% indicating low or null acceptability. However the type of the regimen significantly influenced patients’ acceptability. Single-tablet regimens (STRs, OD regimens with more than one tablet/day or BID regimens were scored as highly acceptable in 84%; 61%; and 53% of cases, respectively (P < 0.0001 (Figure. Statistical significance was retained when the dosing schedule was entered in a multivariate logistic model. When the analysis was restricted to experienced patients 62% of them were currently on a regimen based on a reduced number of pills compared to the previous one. Patients scored the previous regimen as more difficult to comply with in 72% of cases; as difficult in 22% and less difficult in 6%. The eventuality of AEs (40%; respect of timing of

  19. Helicobacter pylori:Effect of coexisting diseases and update on treatment regimens

    Institute of Scientific and Technical Information of China (English)

    Shen-Shong; Chang; Hsiao-Yun; Hu

    2015-01-01

    The presence of concomitant diseases is an independentpredictive factor for non-Helicobacter pylori(H. pylori) peptic ulcers. Patients contracting concomitant diseases have an increased risk of developing ulcer disease through pathogenic mechanisms distinct from those of H. pylori infections. Factors other than H. pylori seem critical in peptic ulcer recurrence in end stage renal disease(ESRD) and cirrhotic patients. However, early H. pylori eradication is associated with a reduced risk of recurrent complicated peptic ulcers in patients with ESRD and liver cirrhosis. Resistances to triple therapy are currently detected using culture-based and molecular methods. Culture susceptibility testing before first- or second-line therapy is unadvisable. Using highly effective empiric first-line and rescue regimens can yield acceptable results. Sequential therapy has been included in a recent consensus report as a valid first-line option for eradicating H. pylori in geographic regions with high clarithromycin resistance. Two novel eradication regimens, namely concomitant and hybrid therapy, have proven more effective in patients with dual-(clarithromycin- and metronidazole-) resistant H. pylori strains. We aim to review the prevalence of and eradication therapy for H. pylori infection in patients with ESRD and cirrhosis. Moreover, we summarized the updated H. pylori eradication regimens.

  20. MULTI-PHASE FRACTURE-MATRIX INTERACTIONS UNDER STRESS CHANGES

    Energy Technology Data Exchange (ETDEWEB)

    A.S. Grader; D. Elsworth; P.M. Halleck; F. Alvarado; A. Alajmi; Z. Karpyn; N. Mohammed; S. Al-Enezi

    2005-06-15

    The main objectives of this project are to quantify the changes in fracture porosity and multiphase transport properties as a function of confining stress. These changes will be integrated into conceptual and numerical models that will improve our ability to predict and optimize fluid transport in fractured system. This report details our progress on: (a) developing the direct experimental measurements of fracture aperture and topology and fluid occupancy using high-resolution x-ray micro-tomography, (b) quantifying the effect of confining stress on the distribution of fracture aperture, and (c) characterization of shear fractures and their impact on multi-phase flow. The three-dimensional surface that describes the large-scale structure of the fracture in the porous medium can be determined using x-ray micro-tomography with significant accuracy. Several fractures have been scanned and the fracture aperture maps have been extracted. The success of the mapping of fracture aperture was followed by measuring the occupancy of the fracture by two immiscible phases, water and decane, and water and kerosene. The distribution of fracture aperture depends on the effective confining stress on the nature of the rock and the type and distribution of the asperities that keep the fracture open. Fracture apertures at different confining stresses were obtained by micro-tomography covering a range of about two thousand psig. Initial analysis of the data shows a significant aperture closure with increase in effective confining stress. Visual descriptions of the process are shown in the report while detailed analysis of the behavior of the distribution of fracture aperture is in progress. Both extensional and shear fractures are being considered. The initial multi-phase flow tests were done in extensional fractures. Several rock samples with induced shear fracture are being studies, and some of the new results are presented in this report. These samples are being scanned in order to

  1. Equations and simulations for multiphase compressible gas-dust flows

    Science.gov (United States)

    Oran, Elaine; Houim, Ryan

    2014-11-01

    Dust-gas multiphase flows are important in physical scenarios such as dust explosions in coal mines, asteroid impact disturbing lunar regolith, and soft aircraft landings dispersing desert or beach sand. In these cases, the gas flow regime can range from highly subsonic and nearly incompressible to supersonic and shock-laden flow, the grain packing can range from fully packed to completely dispersed, and both the gas and the dust can range from chemically inert to highly exothermic. To cover the necessary parameter range in a single model, we solve coupled sets of Navier-Stokes equations describing the background gas and the dust. As an example, a reactive-dust explosion that results in a type of shock-flame complex is described and discussed. Sponsored by the University of Maryland through Minta Martin Endowment Funds in the Department of Aerospace Engineering, and through the Glenn L. Martin Institute Chaired Professorship at the A. James Clark School of Engineering.

  2. Segmented motor drive - with multi-phase induction motor

    DEFF Research Database (Denmark)

    Bendixen, Flemming Buus

    of the induction motor is set up. The model is able to calculate dynamical electric, magnetic and mechanic state variables, but initially it is used to calculate static characteristics in motors with different number of phases and different voltage supply shapes. This analysis show i.e. that the efficiency...... dimensions. The possible torque increase proves to be strongly dependent on the physical dimensions in the initial three-phase motor. The torque increase according to the optimization is listed for a range of Grundfos motors, but in most cases the increase is only a few percent. In a single example...... with 3rd harmonic or square. Another tendency is that the torque ripple is decreased as the number of phases is increased, regardless of the supply type used. Torque ripple can be a source of acoustic noise generation, in this context a multi-phase motor can therefore be an advantage. According...

  3. Computational Fluid Dynamics Simulation of Multiphase Flow in Structured Packings

    Directory of Open Access Journals (Sweden)

    Saeed Shojaee

    2012-01-01

    Full Text Available A volume of fluid multiphase flow model was used to investigate the effective area and the created liquid film in the structured packings. The computational results revealed that the gas and liquid flow rates play significant roles in the effective interfacial area of the packing. In particular, the effective area increases as the flow rates of both phases increase. Numerical results were compared with the Brunazzi and SRP models, and a good agreement between them was found. Attention was given to the process of liquid film formation in both two-dimensional (2D and three-dimensional (3D models. The current study revealed that computational fluid dynamics (CFD can be used as an effective tool to provide information on the details of gas and liquid flows in complex packing geometries.

  4. Multiphase turbulent interstellar medium: some recent results from radio astronomy

    CERN Document Server

    Roy, Nirupam

    2015-01-01

    The radio frequency 1.4 GHz transition of the atomic hydrogen is one of the important tracers of the diffuse neutral interstellar medium. Radio astronomical observations of this transition, using either a single dish telescope or an array interferometer, reveal different properties of the interstellar medium. Such observations are particularly useful to study the multiphase nature and turbulence in the interstellar gas. Observations with multiple radio telescopes have recently been used to study these two closely related aspects in greater detail. Using various observational techniques, the density and the velocity fluctuations in the Galactic interstellar medium was found to have a Kolmogorov-like power law power spectra. The observed power law scaling of the turbulent velocity dispersion with the length scale can be used to derive the true temperature distribution of the medium. Observations from a large ongoing atomic hydrogen absorption line survey have also been used to study the distribution of gas at d...

  5. FEM Modeling of Crack Propagation in a Model Multiphase Alloy

    Institute of Scientific and Technical Information of China (English)

    Lihe QIAN; Seishi NISHIDO; Hiroyuki TODA; Tosliro KOBAYASHI

    2006-01-01

    In this paper, several widely applied fracture criteria were first numerically examined and the crack-tip-region Jintegral criterion was confirmed to be more applicable to predict fracture angle in an elastic-plastic multiphase material. Then, the crack propagation in an idealized dendritic two-phase Al-7%Si alloy was modeled using an elastic-plastic finite element method. The variation of crack growth driving force with crack extension was also demonstrated. It is found that the crack path is significantly influenced by the presence of α-phase near the crack tip, and the crack growth driving force varies drastically from place to place. Lastly, the simulated fracture path in the two-phase model alloy was compared with the experimentally observed fracture path.

  6. Convection in multiphase flows using Lattice Boltzmann methods

    CERN Document Server

    Biferale, L; Sbragaglia, M; Toschi, F

    2011-01-01

    We present high resolution numerical simulations of convection in multiphase flows (boiling) using a novel algorithm based on a Lattice Boltzmann method. We first validate the thermodynamical and kinematical properties of the algorithm. Then, we perform a series of 3d numerical simulations at changing the mean properties in the phase diagram and compare convection with and without phase coexistence at $Ra \\sim 10^7$. We show that in presence of nucleating bubbles non-Oberbeck Boussinesq effects develops, mean temperature profile becomes asymmetric, heat-transfer and heat-transfer fluctuations are enhanced. We also show that small-scale properties of velocity and temperature fields are strongly affected by the presence of buoyant bubble leading to high non-Gaussian profiles in the bulk.

  7. Parallel multiphase field simulations with OpenPhase

    Science.gov (United States)

    Tegeler, Marvin; Shchyglo, Oleg; Kamachali, Reza Darvishi; Monas, Alexander; Steinbach, Ingo; Sutmann, Godehard

    2017-06-01

    The open-source software project OpenPhase allows the three-dimensional simulation of microstructural evolution using the multiphase field method. The core modules of OpenPhase and their implementation as well as their parallelization for a distributed-memory setting are presented. Especially communication and load-balancing strategies are discussed. Synchronization points are avoided by an increased halo-size, i.e. additional layers of ghost cells, which allow multiple stencil operations without data exchange. Load-balancing is considered via graph-partitioning and sub-domain decomposition. Results are presented for performance benchmarks as well as for a variety of applications, e.g. grain growth in polycrystalline materials, including a large number of phase fields as well as Mg-Al alloy solidification.

  8. Pressure Relations and Vertical Equilibrium in the Turbulent, Multiphase ISM

    CERN Document Server

    Koyama, H

    2008-01-01

    We use numerical simulations of turbulent, multiphase, self-gravitating gas orbiting in model disk galaxies to study the relationships among pressure, the vertical gas distribution, and the ratio of dense to diffuse gas. We show that the disk height and mean midplane pressure are consistent with effective hydrostatic equilibrium, provided that the turbulent vertical velocity dispersion and gas self-gravity are included. Mass-weighted pressures are an order of magnitude higher than the midplane pressure because self-gravity concentrates gas and increases the pressure in clouds. We also investigate the ratio Rmol=M(H2)/M(HI) for our simulations. Blitz and Rosolowsky (2006) showed that Rmol is proportional to the estimated midplane pressure. For model series in which the epicyclic frequency, kappa, and gas surface density, Sigma, are proportional, we recover the empirical relation. For other model series in which kappa and Sigma are independent, the midplane pressure and Rmol are not well correlated. We conclude...

  9. 4. Workshop - Measurement techniques of stationary and transient multiphase flow

    Energy Technology Data Exchange (ETDEWEB)

    Prasser, H.M. (ed.)

    2001-05-01

    In November 2000, the 4th Workshop on Measurement Techniques for Stationary and Transient Multiphase Flows took place in Rossendorf. Three previous workshops of this series were national meetings; this time participants from different countries took part. The programme comprised 14 oral presentations, 9 of which are included in these proceedings in full length. A special highlight of the meeting was the main lecture ''Ultrasonic doppler method for bubbly flow measurement'' of Professor Masanori Aritomi, Dr. Hiroshige Kikura and Dr. Yumiko Suzuki. The workshop again dealt with high-resolution phase distribution and phase velocity measurement techniques based on electrical conductivity, ultrasound, laser light and high-speed cinematography. A number of presentations were dedicated to the application of wire-mesh sensors developed by FZR for different applications used by the Technical Universities of Delft and Munich and the Tokyo Institute of Technology. (orig.)

  10. Cesium incorporation in hollandite-rich multiphasic ceramic waste forms

    Science.gov (United States)

    Tumurugoti, P.; Clark, B. M.; Edwards, D. J.; Amoroso, Jake; Sundaram, S. K.

    2017-02-01

    Hollandite-rich multiphase waste form compositions processed by melt-solidification and spark plasma sintering (SPS) were characterized, compared, and validated for nuclear waste incorporation. Phase identification by x-ray diffraction (XRD) and electron back-scattered diffraction (EBSD) confirmed hollandite as the major phase present in these samples along with perovskite, pyrochlore and zirconolite. Distribution of selected elements observed by wavelength dispersive spectroscopy (WDS) maps indicated that Cs formed a secondary phase during SPS processing, which was considered undesirable. On the other hand, Cs partitioned into the hollandite phase in melt-processed samples. Further analysis of hollandite structure in melt-processed composition by selected area electron diffraction (SAED) revealed ordered arrangement of tunnel ions (Ba/Cs) and vacancies, suggesting efficient Cs incorporation into the lattice.

  11. 3d Forced multiphase flow on the pore scale

    Science.gov (United States)

    Scholl, Hagen; Singh, Kamaljit; Scheel, Mario; Dimichiel, Marco; Herminghaus, Stephan; Seemann, Ralf

    2013-11-01

    Using ultra fast x-ray tomography the forced imbibition of an aqueous phase into an initially oil filled matrix is studied. The water is volume controlled flushed into cylindrical columns filled with oil saturated spherical bead packs. The oil displacement is imaged in real time having a spacial resolution of 11 microns and a temporal resolution of about 1 second. To clearly distinguish the aqueous from the oily phase a contrast agent was added to the aqueous phase. The influence of wettability, oil viscosity, gravity and flow velocity was explored and analyzed in terms of temporal development of oil saturation and front shape. It turned out that capillary forces are the key to understand the forced multiphase behavior in the explored parameter range. Funding was provided by the BP-ExploRe project.

  12. Design of multi-phase dynamic chemical networks

    Science.gov (United States)

    Chen, Chenrui; Tan, Junjun; Hsieh, Ming-Chien; Pan, Ting; Goodwin, Jay T.; Mehta, Anil K.; Grover, Martha A.; Lynn, David G.

    2017-08-01

    Template-directed polymerization reactions enable the accurate storage and processing of nature's biopolymer information. This mutualistic relationship of nucleic acids and proteins, a network known as life's central dogma, is now marvellously complex, and the progressive steps necessary for creating the initial sequence and chain-length-specific polymer templates are lost to time. Here we design and construct dynamic polymerization networks that exploit metastable prion cross-β phases. Mixed-phase environments have been used for constructing synthetic polymers, but these dynamic phases emerge naturally from the growing peptide oligomers and create environments suitable both to nucleate assembly and select for ordered templates. The resulting templates direct the amplification of a phase containing only chain-length-specific peptide-like oligomers. Such multi-phase biopolymer dynamics reveal pathways for the emergence, self-selection and amplification of chain-length- and possibly sequence-specific biopolymers.

  13. Collisional broadening of angular correlations in a multiphase transport model

    CERN Document Server

    Edmonds, Terrence; Wang, Fuqiang

    2016-01-01

    Systematic comparisons of jetlike correlation data to radiative and collisional energy loss model calculations are essential to extract transport properties of the quark-gluon medium created in relativistic heavy ion collisions. This paper presents a transport study of collisional broadening of jetlike correlations, by following parton-parton collision history in a multiphase transport (AMPT) model. The correlation shape is studied as a function of the number of parton-parton collisions suffered by a high transverse momentum probe parton ($N_{\\rm coll}$) and the azimuth of the probe relative to the reaction plane ($\\phi_{\\rm fin.}^{\\rm probe}$). Correlation is found to broaden with increasing $N_{\\rm coll}$ and $\\phi_{\\rm fin.}^{\\rm probe}$ from in- to out-of-plane direction. This study provides a transport model benchmark for future jet-medium interaction studies.

  14. Application of microwave reflectometry to disordered petroleum multiphase flow study

    Science.gov (United States)

    Jannier, B.; Dubrunfaut, O.; Ossart, F.

    2013-02-01

    Microwave reflectometry is applied to multiphase flow metering in the context of oil extraction. Our sensor consists of two open-ended coaxial probes operating at complementary frequencies (at 600 MHz and around 36 GHz) and was designed to resist harsh field conditions. This paper presents and comments on results obtained in realistic dynamic conditions, on a triphasic flow loop (water-oil-gas). The main conclusions are the following: Bruggeman-Hanai's mixing rule applies to natural emulsions and can be used to determine the composition of the water-oil liquid phase; results obtained for annular flows are very sensitive to small perturbations such as bubbles or waves at the liquid-gas interface; in the case of triphasic slug flows, the composition of the liquid phase can be estimated by proper filtering of the data.

  15. Analysis of the Multi-Phase Copying Garbage Collection Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Podhorszki, Norbert [ORNL

    2009-01-01

    The multi-phase copying garbage collection was designed to avoid the need for large amount of reserved memory usually required for the copying types of garbage collection algorithms. The collection is performed in multiple phases using the available free memory. This paper proves that the number of phases depends on the size of the reserved memory and the ratio of the garbage and accessible objects. The performance of the implemented algorithm is tested in a fine-grained parallel Prolog system. We find that reserving only 10% of memory for garbage collection is sufficient for good performance in practice. Additionally, an improvement of the generic algorithm specifically for the tested parallel Prolog system is described.

  16. Quantitative multiphase analysis of archaeological bronzes by neutron diffraction

    CERN Document Server

    Siano, S; Celli, M; Pini, R; Salimbeni, R; Zoppi, M; Kockelmann, W A; Iozzo, M; Miccio, M; Moze, O

    2002-01-01

    In this paper, we report the first investigation on the potentials of neutron diffraction to characterize archaeological bronze artifacts. The preliminary feasibility of phase and structural analysis was demonstrated on standardised specimens with a typical bronze alloy composition. These were realised through different hardening and annealing cycles, simulating possible ancient working techniques. The Bragg peak widths that resulted were strictly dependent on the working treatment, thus providing an important analytical element to investigate ancient making techniques. The diagnostic criteria developed on the standardised specimens were then applied to study two Etruscan museum pieces. Quantitative multiphase analysis by Rietveld refinement of the diffraction patterns was successfully demonstrated. Furthermore, the analysis of patterns associated with different artifact elements also yielded evidence for some peculiar perspective of the neutron diffraction diagnostics in archeometric applications. (orig.)

  17. Segmented motor drive - with multi-phase induction motor

    DEFF Research Database (Denmark)

    Bendixen, Flemming Buus

    This PhD project commences in modulation of motor drives, i.e. having the advantage of reducing the number of variants and improves the system reliability at error situations. Four different motor drive topologies with modular construction as common denominator are compared on a general level....... The multi-phase motor is selected for further analysis. The project is limited to examine if increasing the number of phases can improve the characteristics for induction motor drives. In the literature it is demonstrated that torque production in a six-phase motor can be increased, if a 3rd harmonic...... current with 1/6 amplitude is added to the 1st harmonic current. This claim is verified and the optimization of the motor design is extended to, beyond the stator tooth width, also to include the inner diameter of the stator. This means that the lamination sheet is optimized according to two geometrical...

  18. Computational algorithms for multiphase magnetohydrodynamics and applications to accelerator targets

    Directory of Open Access Journals (Sweden)

    R.V. Samulyak

    2010-01-01

    Full Text Available An interface-tracking numerical algorithm for the simulation of magnetohydrodynamic multiphase/free surface flows in the low-magnetic-Reynolds-number approximation of (Samulyak R., Du J., Glimm J., Xu Z., J. Comp. Phys., 2007, 226, 1532 is described. The algorithm has been implemented in multi-physics code FronTier and used for the simulation of MHD processes in liquids and weakly ionized plasmas. In this paper, numerical simulations of a liquid mercury jet entering strong and nonuniform magnetic field and interacting with a powerful proton pulse have been performed and compared with experiments. Such a mercury jet is a prototype of the proposed Muon Collider/Neutrino Factory, a future particle accelerator. Simulations demonstrate the elliptic distortion of the mercury jet as it enters the magnetic solenoid at a small angle to the magnetic axis, jet-surface instabilities (filamentation induced by the interaction with proton pulses, and the stabilizing effect of the magnetic field.

  19. Linear Power-Flow Models in Multiphase Distribution Networks: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, Andrey; Dall' Anese, Emiliano

    2017-05-26

    This paper considers multiphase unbalanced distribution systems and develops approximate power-flow models where bus-voltages, line-currents, and powers at the point of common coupling are linearly related to the nodal net power injections. The linearization approach is grounded on a fixed-point interpretation of the AC power-flow equations, and it is applicable to distribution systems featuring (i) wye connections; (ii) ungrounded delta connections; (iii) a combination of wye-connected and delta-connected sources/loads; and, (iv) a combination of line-to-line and line-to-grounded-neutral devices at the secondary of distribution transformers. The proposed linear models can facilitate the development of computationally-affordable optimization and control applications -- from advanced distribution management systems settings to online and distributed optimization routines. Performance of the proposed models is evaluated on different test feeders.

  20. Operational Transresistance Amplifier-Based Multiphase Sinusoidal Oscillators

    Directory of Open Access Journals (Sweden)

    Rajeshwari Pandey

    2011-01-01

    Full Text Available Multiphase sinusoidal oscillator circuits are presented which utilize Operational Transresistance Amplifier (OTRA as the active element. The first circuit produces n odd-phase oscillations of equal amplitudes and equally spaced in phase. The second circuit is capable of producing n odd- or even- phase oscillations equally spaced in phase. An alternative approach is discussed in the third circuit, which utilizes a single-phase tunable oscillator circuit which is used to inject signals into a phase shifter circuits. An automatic gain control (AGC circuit has been implemented for the second and third circuit. The circuits are simple to realize and have a low component count. PSPICE simulations have been given to verify the theoretical analysis. The experimental outcome corroborates the theoretical propositions and simulated results.

  1. Multiphase model for transformation induced plasticity. Extended Leblond's model

    Science.gov (United States)

    Weisz-Patrault, Daniel

    2017-09-01

    Transformation induced plasticity (TRIP) classically refers to plastic strains observed during phase transitions that occur under mechanical loads (that can be lower than the yield stress). A theoretical approach based on homogenization is proposed to deal with multiphase changes and to extend the validity of the well known and widely used model proposed by Leblond (1989). The approach is similar, but several product phases are considered instead of one and several assumptions have been released. Thus, besides the generalization for several phases, one can mention three main improvements in the calculation of the local equivalent plastic strain: the deviatoric part of the phase transformation is taken into account, both parent and product phases are elastic-plastic with linear isotropic hardening and the applied stress is considered. Results show that classical issues of singularities arising in the Leblond's model (corrected by ad hoc numerical functions or thresholding) are solved in this contribution excepted when the applied equivalent stress reaches the yield stress. Indeed, in this situation the parent phase is entirely plastic as soon as the phase transformation begins and the same singularity as in the Leblond's model arises. A physical explanation of the cutoff function is introduced in order to regularize the singularity. Furthermore, experiments extracted from the literature dealing with multiphase transitions and multiaxial loads are compared with the original Leblond's model and the proposed extended version. For the extended version, very good agreement is observed without any fitting procedures (i.e., material parameters are extracted from other dedicated experiments) and for the original version results are more qualitative.

  2. Advanced tomographic flow diagnostics for opaque multiphase fluids

    Energy Technology Data Exchange (ETDEWEB)

    Torczynski, J.R.; O`Hern, T.J.; Adkins, D.R.; Jackson, N.B.; Shollenberger, K.A.

    1997-05-01

    This report documents the work performed for the ``Advanced Tomographic Flow Diagnostics for Opaque Multiphase Fluids`` LDRD (Laboratory-Directed Research and Development) project and is presented as the fulfillment of the LDRD reporting requirement. Dispersed multiphase flows, particularly gas-liquid flows, are industrially important to the chemical and applied-energy industries, where bubble-column reactors are employed for chemical synthesis and waste treatment. Due to the large range of length scales (10{sup {minus}6}-10{sup 1}m) inherent in real systems, direct numerical simulation is not possible at present, so computational simulations are forced to use models of subgrid-scale processes, the accuracy of which strongly impacts simulation fidelity. The development and validation of such subgrid-scale models requires data sets at representative conditions. The ideal measurement techniques would provide spatially and temporally resolved full-field measurements of the distributions of all phases, their velocity fields, and additional associated quantities such as pressure and temperature. No technique or set of techniques is known that satisfies this requirement. In this study, efforts are focused on characterizing the spatial distribution of the phases in two-phase gas-liquid flow and in three-phase gas-liquid-solid flow. Due to its industrial importance, the bubble-column geometry is selected for diagnostics development and assessment. Two bubble-column testbeds are utilized: one at laboratory scale and one close to industrial scale. Several techniques for measuring the phase distributions at conditions of industrial interest are examined: level-rise measurements, differential-pressure measurements, bulk electrical impedance measurements, electrical bubble probes, x-ray tomography, gamma-densitometry tomography, and electrical impedance tomography.

  3. Hypofractionation regimens for stereotactic radiotherapy for large brain tumors.

    Science.gov (United States)

    Yuan, Jiankui; Wang, Jian Z; Lo, Simon; Grecula, John C; Ammirati, Mario; Montebello, Joseph F; Zhang, Hualin; Gupta, Nilendu; Yuh, William T C; Mayr, Nina A

    2008-10-01

    To investigate equivalent regimens for hypofractionated stereotactic radiotherapy (HSRT) for brain tumor treatment and to provide dose-escalation guidance to maximize the tumor control within the normal brain tolerance. The linear-quadratic model, including the effect of nonuniform dose distributions, was used to evaluate the HSRT regimens. The alpha/beta ratio was estimated using the Gammaknife stereotactic radiosurgery (GKSRS) and whole-brain radiotherapy experience for large brain tumors. The HSRT regimens were derived using two methods: (1) an equivalent tumor control approach, which matches the whole-brain radiotherapy experience for many fractions and merges it with the GKSRS data for few fractions; and (2) a normal-tissue tolerance approach, which takes advantages of the dose conformity and fractionation of HSRT to approach the maximal dose tolerance of the normal brain. A plausible alpha/beta ratio of 12 Gy for brain tumor and a volume parameter n of 0.23 for normal brain were derived from the GKSRS and whole-brain radiotherapy data. The HSRT prescription regimens for the isoeffect of tumor irradiation were calculated. The normal-brain equivalent uniform dose decreased as the number of fractions increased, because of the advantage of fractionation. The regimens for potential dose escalation of HSRT within the limits of normal-brain tolerance were derived. The designed hypofractionated regimens could be used as a preliminary guide for HSRT dose prescription for large brain tumors to mimic the GKSRS experience and for dose escalation trials. Clinical studies are necessary to further tune the model parameters and validate these regimens.

  4. A Multi-Phase Chemo-Dynamical SPH Code for Galaxy Evolution

    OpenAIRE

    Berczik, P.; Hensler, G.; Theis, Ch.; Spurzem, R.

    2003-01-01

    In this paper we present some test results of our newly developed Multi-Phase Chemo-Dynamical Smoothed Particle Hydrodynamics (MP- CD-SPH) code for galaxy evolution. At first, we present a test of the ``pure'' hydro SPH part of the code. Then we describe and test the multi-phase description of the gaseous components of the interstellar matter. In this second part we also compare our condensation and evaporation description with the results of a previous 2d multi-phase hydrodynamic mesh code.

  5. Multiphase flow analysis using population balance modeling bubbles, drops and particles

    CERN Document Server

    Yeoh, Guan Heng; Tu, Jiyuan

    2013-01-01

    Written by leading multiphase flow and CFD experts, this book enables engineers and researchers to understand the use of PBM and CFD frameworks. Population balance approaches can now be used in conjunction with CFD, effectively driving more efficient and effective multiphase flow processes. Engineers familiar with standard CFD software, including ANSYS-CFX and ANSYS-Fluent, will be able to use the tools and approaches presented in this book in the effective research, modeling and control of multiphase flow problems. Builds a complete understanding of the theory behind the

  6. A multiphase ion-transport analysis of the electrostatic disjoining pressure: implications for binary droplet coalescence

    Science.gov (United States)

    Mason, Lachlan; Gebauer, Felix; Bart, Hans-Jörg; Stevens, Geoffrey; Harvie, Dalton

    2016-11-01

    Understanding the physics of emulsion coalescence is critical for the robust simulation of industrial solvent extraction processes, in which loaded organic and raffinate phases are separated via the coalescence of dispersed droplets. At the droplet scale, predictive collision-outcome models require an accurate description of the repulsive surface forces arising from electrical-double-layer interactions. The conventional disjoining-pressure treatment of double-layer forces, however, relies on assumptions which do not hold generally for deformable droplet collisions: namely, low interfacial curvature and negligible advection of ion species. This study investigates the validity bounds of the disjoining pressure approximation for low-inertia droplet interactions. A multiphase ion-transport model, based on a coupling of droplet-scale Nernst-Planck and Navier-Stokes equations, predicts ion-concentration fields that are consistent with the equilibrium Boltzmann distribution; indicating that the disjoining-pressure approach is valid for both static and dynamic interactions in low-Reynolds-number settings. The present findings support the development of coalescence kernels for application in macro-scale population balance modelling.

  7. Multiphase blends from poly(L-lactide) and poly(methyl mathacrylate).

    Science.gov (United States)

    Le, Kim-Phuong; Lehman, Richard; Remmert, Jessica; Vanness, Kenneth; Ward, Paula Marie L; Idol, James D

    2006-01-01

    Melt processing of poly(L-lactide) (PLLA) and poly(methyl methacrylate) (PMMA) was conducted over a targeted range of compositions with PLLAs of 118 and 316 kDa in molecular mass to identify morphologies and the phase relationships in these blends. These blends are of interest for use in biomaterials and the morphologies are critical for tissue-engineering studies where biodegradability, pore connectivity and surface texture control tissue viability and adhesion. Simple extrusion of the two polymers produced multiphase blends with an average domain size near 25 microm. Scanning electron microscopy and dynamic mechanical analysis demonstrated that these blends are immiscible, at least in a metastable sense, and regions of co-continuous structures were identified. Such co-continuous, which occurred generally in accordance with rheology prediction models, exhibit a fine interconnected structure that appears effective for fabricating certain biomaterials. A broad and unexpected transition appears in these blends, as measured by modulated differential scanning calorimetry between 70 and 100 degrees C, which may be the glass transition temperature of an alloy phase. The magnitude of this transition is greatest in the fine-structured co-continuous composition region of blends, suggesting the presence of a complex or other derivative of the two primary phases.

  8. A semi-analytic model of the turbulent multi-phase interstellar medium

    Science.gov (United States)

    Braun, H.; Schmidt, W.

    2012-04-01

    We present a semi-analytic model for the interstellar medium that considers local processes and structures of turbulent star-forming gas. A volume element of the interstellar medium is described as a multi-phase system, comprising a cold and a warm gas phase in effective (thermal plus turbulent) pressure equilibrium and a stellar component. The cooling instability of the warm gas feeds the cold phase, while various heating processes transfer cold gas to the warm phase. The cold phase consists of clumps embedded in diffuse warm gas, where only the molecular fraction of the cold gas may be converted into stars. The fraction of molecular gas is approximately calculated, using a Strömgren-like approach and the efficiency of star formation is determined by the state of the cold gas and the turbulent velocity dispersion on the clump length-scale. Gas can be heated by supernovae and ultraviolet emission of massive stars, according to the evolutionary stages of the stellar populations and the initial mass function. Since turbulence has a critical impact on the shape of the gaseous phases, on the production of molecular hydrogen and on the formation of stars, the consistent treatment of turbulent energy - the kinetic energy of unresolved motions - is an important new feature of our model. Besides turbulence production by supernovae and the cooling instability, we also take into account the forcing by large-scale motions. We formulate a set of ordinary differential equations, which statistically describes star formation and the exchange between the different budgets of mass and energy in a region of the interstellar medium with given mean density, size, metallicity and external turbulence forcing. By exploring the behaviour of the solutions, we find equilibrium states, in which the star formation efficiencies are consistent with observations. Kennicutt-Schmidt-like relations naturally arise from the equilibrium solutions, while conventional star formation models in

  9. Oxytocin regimen for labor augmentation, labor progression, and perinatal outcomes.

    Science.gov (United States)

    Zhang, Jun; Branch, D Ware; Ramirez, Mildred M; Laughon, S Katherine; Reddy, Uma; Hoffman, Mathew; Bailit, Jennifer; Kominiarek, Michelle; Chen, Zhen; Hibbard, Judith U

    2011-08-01

    To examine the effects and safety of high-dose (compared with low-dose) oxytocin regimen for labor augmentation on perinatal outcomes. Data from the Consortium on Safe Labor were used. A total of 15,054 women from six hospitals were eligible for the analysis. Women were grouped based on their oxytocin starting dose and incremental dosing of 1, 2, and 4 milliunits/min. Duration of labor and a number of maternal and neonatal outcomes were compared among these three groups stratified by parity. Multivariable logistic regression and generalized linear mixed model were used to adjust for potential confounders. Oxytocin regimen did not affect the rate of cesarean delivery or other perinatal outcomes. Compared with 1 milliunit/min, the regimens starting with 2 milliunits/min and 4 milliunits/min reduced the duration of first stage by 0.8 hours (95% confidence interval 0.5-1.1) and 1.3 hours (1.0-1.7), respectively, in nulliparous women. No effect was observed on the second stage of labor. Similar patterns were observed in multiparous women. High-dose regimen was associated with a reduced risk of meconium stain, chorioamnionitis, and newborn fever in multiparous women. High-dose oxytocin regimen (starting dose at 4 milliunits/min and increment of 4 millliunits/min) is associated with a shorter duration of first-stage of labor for all parities without increasing the cesarean delivery rate or adversely affecting perinatal outcomes. II.

  10. Development of antibiotic regimens using graph based evolutionary algorithms.

    Science.gov (United States)

    Corns, Steven M; Ashlock, Daniel A; Bryden, Kenneth M

    2013-12-01

    This paper examines the use of evolutionary algorithms in the development of antibiotic regimens given to production animals. A model is constructed that combines the lifespan of the animal and the bacteria living in the animal's gastro-intestinal tract from the early finishing stage until the animal reaches market weight. This model is used as the fitness evaluation for a set of graph based evolutionary algorithms to assess the impact of diversity control on the evolving antibiotic regimens. The graph based evolutionary algorithms have two objectives: to find an antibiotic treatment regimen that maintains the weight gain and health benefits of antibiotic use and to reduce the risk of spreading antibiotic resistant bacteria. This study examines different regimens of tylosin phosphate use on bacteria populations divided into Gram positive and Gram negative types, with a focus on Campylobacter spp. Treatment regimens were found that provided decreased antibiotic resistance relative to conventional methods while providing nearly the same benefits as conventional antibiotic regimes. By using a graph to control the information flow in the evolutionary algorithm, a variety of solutions along the Pareto front can be found automatically for this and other multi-objective problems.

  11. Specific tolerance induction across a xenogeneic barrier: production of mixed rat/mouse lymphohematopoietic chimeras using a nonlethal preparative regimen

    OpenAIRE

    1990-01-01

    The development of safe methods for inducing donor-specific tolerance across xenogeneic barriers could potentially relieve the critical shortage of allograft donors that currently limits the applicability of organ transplantation. We report here that such tolerance can be induced in a xenogeneic combination (rat----mouse) using a nonmyeloablative and nonlethal preparative regimen. Successful induction of chimerism and donor-specific transplantation tolerance required pretreatment of recipient...

  12. CFD Simulation of Liquid-solid Multiphase Flow in Mud Mixer

    Directory of Open Access Journals (Sweden)

    T.Y. Kim

    2016-08-01

    Full Text Available In the present study, a computational fluid dynamics (CFD simulation was performed to analyze the mixing phenomena associated with multi-phase flow in a mud mixing system. For the validation of CFD simulation, firstly a liquid-solid multiphase flow inside horizontal pipe was simulated and compared with the experiments and other numerical simulations. And then, the multiphase flow simulation was carried out for the mud mixer in the drilling handling system in order to understand mixing phenomena and predict the mixing efficiency. For the modeling and simulation, a commercial software, STAR-CCM+, based on a finite-volume method (FVM was adopted. The simulation results for liquid-solid flow inside the pipe shows a good agreement with the experimental data. With the same multiphase model, the simulation for mud mixer is performed under the generalized boundary condition and then pressure drop through the mud mixer will be discussed.

  13. Characterization of NbC and (Nb, Ti)N nanoprecipitates in TRIP assisted multiphase steels

    NARCIS (Netherlands)

    Tirumalasetty, G.K.; Van Huis, M.A.; Fang, C.M.; Xu, Q.; Tichelaar, F.D.; Hanlon, D.N.; Sietsma, J.; Zandbergen, H.W.

    2011-01-01

    Multiphase steels utilising composite strengthening may be further strengthened via grain refinement or precipitation by the addition of microalloying elements. In this study a Nb microalloyed steel comprising martensite, bainite and retained austenite has been studied. By means of transmission

  14. Characteristics of HIV antiretroviral regimen and treatment adherence

    Directory of Open Access Journals (Sweden)

    Vera Lúcia da Silveira

    2003-06-01

    Full Text Available The relationship between characteristics of HIV antiretroviral regimens and treatment adherence was studied in adolescent and adult patients who underwent antiretroviral therapy from January 1998 to September 2000, at the Service for Specialized Assistance in Pelotas. The patients were interviewed on two occasions, and the use of antiretrovirals during the previous 48 hours was investigated by a self-report. Adherence was defined as use of 95% or more of the prescribed medication. Social-demographic variables were collected through direct questionnaires. The antiretroviral regimen and clinical data were copied from the patients' records. Associations between the independent variables and adherence were analyzed by means of logistic regression. The multivariate analysis included characteristics of the antiretroviral regimens, social-demographic variables, as well as perception of negative effects, negative physiological states, and adverse effects of the treatment. Among the 224 selected patients, 194 participated in our study. Their ages varied from 17 to 67 years; most patients were men, with few years of schooling and a low family income. Only 49% adhered to the treatment. Adherence to treatment regimens was reduced when more daily doses were indicated: three to four doses (odds ratio of adherence to treatment (OR=0.47, 95% confidence interval (CI 0.22-1.01 and five to six (OR=0.24, 95% CI 0.09-0.62; two or more doses taken in a fasting state (OR=0.59, 95% CI 0.11-0.68, and for patients who reported adverse effects to the treatment (OR=0.39, 95% CI 0.19-0.77. Most of the regimens with more than two daily doses of medication included at least one dose apart from mealtimes. The results suggest that, if possible, regimens with a reduced number of doses should be chosen, with no compulsory fasting, and with few adverse effects. Strategies to minimize these effects should be discussed with the patients.

  15. Characteristics of HIV antiretroviral regimen and treatment adherence

    Directory of Open Access Journals (Sweden)

    Vera Lúcia da Silveira

    Full Text Available The relationship between characteristics of HIV antiretroviral regimens and treatment adherence was studied in adolescent and adult patients who underwent antiretroviral therapy from January 1998 to September 2000, at the Service for Specialized Assistance in Pelotas. The patients were interviewed on two occasions, and the use of antiretrovirals during the previous 48 hours was investigated by a self-report. Adherence was defined as use of 95% or more of the prescribed medication. Social-demographic variables were collected through direct questionnaires. The antiretroviral regimen and clinical data were copied from the patients' records. Associations between the independent variables and adherence were analyzed by means of logistic regression. The multivariate analysis included characteristics of the antiretroviral regimens, social-demographic variables, as well as perception of negative effects, negative physiological states, and adverse effects of the treatment. Among the 224 selected patients, 194 participated in our study. Their ages varied from 17 to 67 years; most patients were men, with few years of schooling and a low family income. Only 49% adhered to the treatment. Adherence to treatment regimens was reduced when more daily doses were indicated: three to four doses (odds ratio of adherence to treatment (OR=0.47, 95% confidence interval (CI 0.22-1.01 and five to six (OR=0.24, 95% CI 0.09-0.62; two or more doses taken in a fasting state (OR=0.59, 95% CI 0.11-0.68, and for patients who reported adverse effects to the treatment (OR=0.39, 95% CI 0.19-0.77. Most of the regimens with more than two daily doses of medication included at least one dose apart from mealtimes. The results suggest that, if possible, regimens with a reduced number of doses should be chosen, with no compulsory fasting, and with few adverse effects. Strategies to minimize these effects should be discussed with the patients.

  16. Intra-abdominal desmoplastic small round-cell tumour: multiphase CT findings in two children

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Hyoung; Goo, Hyun Woo; Yoon, Chong Hyun [Department of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-2 dong, Songpa-gu, Seoul, 138-736 (Korea)

    2003-06-01

    We report the multiphase CT findings of intra-abdominal desmoplastic small round-cell tumour (DSRCT) in two children. CT showed a huge heterogeneous intraperitoneal mass with or without direct invasion into solid organs such as liver or kidney, extensive intraperitoneal seeding, intratumoural calcification, ascites, and lymphadenopathy. DSRCT should be included in the differential diagnosis of malignant intraperitoneal neoplasm in children. Multiphase CT may be helpful in delineating tumour extent, vascularity and direct invasion into adjacent organs. (orig.)

  17. An original combined multiphase model of the steam-explosion premixing phase

    OpenAIRE

    Leskovar, Matjaž; Mavko, Borut

    2015-01-01

    In multiphase flow, different distributions can occur that cannot be adequately modeled with just free-surface models or with just multiphase models. Such a distribution of phases occurs for example, in isothermal steam-explosion premixing experiments, where dispersed spheres penetrate the water and the water-air surface remains sharp. A common practice when modeling isothermal premixing experiments is to treat all three phases involved - the water, the air and the spheres phase - equally, wi...

  18. Monitoring sand particle concentration in multiphase flow using acoustic emission technology

    OpenAIRE

    El-Alej, Mohamed Essid

    2014-01-01

    Multiphase flow is the simultaneous flow of two or several phases through a system such as a pipe. This common phenomenon can be found in the petroleum and chemical engineering industrial fields. Transport of sand particles in multiphase production has attracted considerable attention given sand production is a common problem especially to the oil and gas industry. The sand production causes loss of pipe wall thickness which can lead to expensive failures and loss of product...

  19. On the physics and mechanics of phase transformations in TRIP-assisted multiphase steels

    OpenAIRE

    Jacques, Pascal

    1999-01-01

    The subject of this thesis is twofold: (i) to contribute to the understanding of the phase transformations and mechanical properties of TRIP-assisted multiphase steels; (ii) to show to what extent a new TRIP-assisted multiphase steel with a reduced silicon content could meet the performance requirements for high-strength formable steels. It enlightens the correlations between Processing, Microstructure and Properties. Furthermore, the different investigations carried out in this thesis will a...

  20. Limitations of predicting in vivo biostability of multiphase polyurethane elastomers using temperature-accelerated degradation testing.

    Science.gov (United States)

    Padsalgikar, Ajay; Cosgriff-Hernandez, Elizabeth; Gallagher, Genevieve; Touchet, Tyler; Iacob, Ciprian; Mellin, Lisa; Norlin-Weissenrieder, Anna; Runt, James

    2015-01-01

    Polyurethane biostability has been the subject of intense research since the failure of polyether polyurethane pacemaker leads in the 1980s. Accelerated in vitro testing has been used to isolate degradation mechanisms and predict clinical performance of biomaterials. However, validation that in vitro methods reproduce in vivo degradation is critical to the selection of appropriate tests. High temperature has been proposed as a method to accelerate degradation. However, correlation of such data to in vivo performance is poor for polyurethanes due to the impact of temperature on microstructure. In this study, we characterize the lack of correlation between hydrolytic degradation predicted using a high temperature aging model of a polydimethylsiloxane-based polyurethane and its in vivo performance. Most notably, the predicted molecular weight and tensile property changes from the accelerated aging study did not correlate with clinical explants subjected to human biological stresses in real time through 5 years. Further, DMTA, ATR-FTIR, and SAXS experiments on samples aged for 2 weeks in PBS indicated greater phase separation in samples aged at 85°C compared to those aged at 37°C and unaged controls. These results confirm that microstructural changes occur at high temperatures that do not occur at in vivo temperatures. In addition, water absorption studies demonstrated that water saturation levels increased significantly with temperature. This study highlights that the multiphase morphology of polyurethane precludes the use of temperature accelerated biodegradation for the prediction of clinical performance and provides critical information in designing appropriate in vitro tests for this class of materials.

  1. Well testing for radially heterogeneous reservoirs under single and multiphase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, L.G.; Reynolds, A.C. [Univ. of Tulsa, OK (United States)

    1997-03-01

    In this work, the authors examine the behavior of pressure-transient data for single and multiphase flow in radially heterogeneous reservoirs. To illustrate multiphase flow behavior in these systems, they focus on heterogeneous gas-condensate reservoirs; however, they also consider other multiphase flow problems. It is well known that in some instances, e.g., water injection/falloff in homogeneous reservoirs, pressure-transient data from buildup (or falloff) tests cannot be obtained by superposition of drawdown (injection) pressure responses. In fact, drawdown and buildup reflect properties in different regions of the reservoir. This behavior is common to most occurrences of multiphase reservoir flow and is exaggerated in the presence of radial heterogeneity. This theoretical work describes the information contained in transient pressure derivative data and explains the fundamental difference in behavior between multiphase drawdown and buildup pressure-transient data in radially heterogeneous reservoirs. The authors show that multiphase buildup data may be treated like single-phase buildup data, but drawdown data is most indicative of properties in that region of the reservoir where mobility is changing most rapidly with time.

  2. Well testing for heterogeneous reservoirs under single and multiphase flow conditions

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, L.G.; Reynolds, A.C. [Univ. of Tulsa, OK (United States)

    1995-12-31

    In this work, we examine the behavior of pressure transient data for single and multiphase flow in heterogeneous reservoirs. In order to illustrate multiphase flow behavior in these systems, we focus on heterogeneous gas condensate reservoirs, however, we also consider other multiphase flow problems. It is well known that in some instances, e. g., water injection/falloff in homogeneous reservoirs, pressure transient data from buildup (or falloff) tests cannot be obtained by superposition of drawdown (injection) pressure responses. In fact, drawdown and buildup reflect properties in different regions of the reservoir. This behavior is common to most occurrences of multiphase reservoir flow, and is exaggerated in the presence of radial heterogeneity. This theoretical work describes the information contained in transient pressure derivative data, and explains the fundamental difference in behavior between multiphase drawdown and buildup pressure transient data in radially heterogeneous reservoirs. We show that whereas multiphase buildup data may be treated like single-phase buildup data, drawdown data is most indicative of properties in that region of the reservoir where mobility is changing most rapidly with time.

  3. CriticalEd

    DEFF Research Database (Denmark)

    Kjellberg, Caspar Mølholt; Meredith, David

    2014-01-01

    The best text method is commonly applied among music scholars engaged in producing critical editions. In this method, a comment list is compiled, consisting of variant readings and editorial emendations. This list is maintained by inserting the comments into a document as the changes are made....... Since the comments are not input sequentially, with regard to position, but in arbitrary order, this list must be sorted by copy/pasting the rows into place—an error-prone and time-consuming process. Scholars who produce critical editions typically use off-the-shelf music notation software...... such as Sibelius or Finale. It was hypothesized that it would be possible to develop a Sibelius plug-in, written in Manuscript 6, that would improve the critical editing work flow, but it was found that the capabilities of this scripting language were insufficient. Instead, a 3-part system was designed and built...

  4. Multiphase transport in polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Gauthier, Eric D.

    Polymer electrolyte membrane fuel cells (PEMFCs) enable efficient conversion of fuels to electricity. They have enormous potential due to the high energy density of the fuels they utilize (hydrogen or alcohols). Power density is a major limitation to wide-scale introduction of PEMFCs. Power density in hydrogen fuel cells is limited by accumulation of water in what is termed fuel cell `flooding.' Flooding may occur in either the gas diffusion layer (GDL) or within the flow channels of the bipolar plate. These components comprise the electrodes of the fuel cell and balance transport of reactants/products with electrical conductivity. This thesis explores the role of electrode materials in the fuel cell and examines the fundamental connection between material properties and multiphase transport processes. Water is generated at the cathode catalyst layer. As liquid water accumulates it will utilize the largest pores in the GDL to go from the catalyst layer to the flow channels. Water collects to large pores via lateral transport at the interface between the GDL and catalyst layer. We have shown that water may be collected in these large pores from several centimeters away, suggesting that we could engineer the GDL to control flooding with careful placement and distribution of large flow-directing pores. Once liquid water is in the flow channels it forms slugs that block gas flow. The slugs are pushed along the channel by a pressure gradient that is dependent on the material wettability. The permeable nature of the GDL also plays a major role in slug growth and allowing bypass of gas between adjacent channels. Direct methanol fuel cells (DMFCs) have analogous multiphase flow issues where carbon dioxide bubbles accumulate, `blinding' regions of the fuel cell. This problem is fundamentally similar to water management in hydrogen fuel cells but with a gas/liquid phase inversion. Gas bubbles move laterally through the porous GDL and emerge to form large bubbles within the

  5. Compositional multiphase flow and transport in heterogeneous porous media

    Energy Technology Data Exchange (ETDEWEB)

    Huber, R.U.

    2000-07-01

    This work first treats the conceptual models for the description of multiphase flow processes in porous media. The thermodynamic laws are explained and the description and quantification of multi-fluid equilibria are discussed in order to account for fluid composition. The fully and weakly coupled approaches for the mathematical description of such flow processes with respect to systems consisting of two and three fluid phases as well as with respect to compositional single and multiphase systems are assessed. For the discretization of the two-phase flow equations node- and cell-centered finite volume methods and mixed and mixed-hybrid finite element approaches are applied. Based upon these methods five solution algorithms are developed. Four of these algorithms are based on the simultaneous solution of the discretized equations in combination with the Newton-Raphson technique. Methods 1 and 2 treat two- three-phase flow processes, Method 3 applies to the solution of partially miscible three-component systems while Method 4 is created for three-phase three-component systems. The latter method uses a variable substitution dependent on the local presence of the fluid phases. Method 5 is based on the IMPES/IMPESC concept. The time-implicit pressure equation is discretized with the mixed-hybrid finite element method. The saturation and concentration equations, respectively, are solved with a cell-centered finite volume scheme. The developed algorithms are applied to the two- and three-phase Buckley-Leverett problems. A partitioning interwell tracer test is simulated. The propagation behavior of nonaqueous phase liquids (NAPLs) in the saturated and unsaturated ground zone under the influence of heterogeneities are examined. In addition, a larger-scale experiment is simulated, which involves an injection of trichloroethylene into the subsurface and the subsequent distribution. Here, the development of a dissolved contaminant plume as well as the behavior of organic

  6. Experimental characterization of energetic material dynamics for multiphase blast simulation.

    Energy Technology Data Exchange (ETDEWEB)

    Beresh, Steven Jay; Wagner, Justin L.; Kearney, Sean Patrick; Wright, Elton K.; Baer, Melvin R.; Pruett, Brian Owen Matthew

    2011-09-01

    Currently there is a substantial lack of data for interactions of shock waves with particle fields having volume fractions residing between the dilute and granular regimes, which creates one of the largest sources of uncertainty in the simulation of energetic material detonation. To close this gap, a novel Multiphase Shock Tube has been constructed to drive a planar shock wave into a dense gas-solid field of particles. A nearly spatially isotropic field of particles is generated in the test section by a gravity-fed method that results in a spanwise curtain of spherical 100-micron particles having a volume fraction of about 19%. Interactions with incident shock Mach numbers of 1.66, 1.92, and 2.02 were achieved. High-speed schlieren imaging simultaneous with high-frequency wall pressure measurements are used to reveal the complex wave structure associated with the interaction. Following incident shock impingement, transmitted and reflected shocks are observed, which lead to differences in particle drag across the streamwise dimension of the curtain. Shortly thereafter, the particle field begins to propagate downstream and spread. For all three Mach numbers tested, the energy and momentum fluxes in the induced flow far downstream are reduced about 30-40% by the presence of the particle field. X-Ray diagnostics have been developed to penetrate the opacity of the flow, revealing the concentrations throughout the particle field as it expands and spreads downstream with time. Furthermore, an X-Ray particle tracking velocimetry diagnostic has been demonstrated to be feasible for this flow, which can be used to follow the trajectory of tracer particles seeded into the curtain. Additional experiments on single spherical particles accelerated behind an incident shock wave have shown that elevated particle drag coefficients can be attributed to increased compressibility rather than flow unsteadiness, clarifying confusing results from the historical database of shock tube

  7. Experimental characterization of energetic material dynamics for multiphase blast simulation.

    Energy Technology Data Exchange (ETDEWEB)

    Beresh, Steven Jay; Wagner, Justin L.; Kearney, Sean Patrick; Wright, Elton K.; Baer, Melvin R.; Pruett, Brian Owen Matthew

    2011-09-01

    Currently there is a substantial lack of data for interactions of shock waves with particle fields having volume fractions residing between the dilute and granular regimes, which creates one of the largest sources of uncertainty in the simulation of energetic material detonation. To close this gap, a novel Multiphase Shock Tube has been constructed to drive a planar shock wave into a dense gas-solid field of particles. A nearly spatially isotropic field of particles is generated in the test section by a gravity-fed method that results in a spanwise curtain of spherical 100-micron particles having a volume fraction of about 19%. Interactions with incident shock Mach numbers of 1.66, 1.92, and 2.02 were achieved. High-speed schlieren imaging simultaneous with high-frequency wall pressure measurements are used to reveal the complex wave structure associated with the interaction. Following incident shock impingement, transmitted and reflected shocks are observed, which lead to differences in particle drag across the streamwise dimension of the curtain. Shortly thereafter, the particle field begins to propagate downstream and spread. For all three Mach numbers tested, the energy and momentum fluxes in the induced flow far downstream are reduced about 30-40% by the presence of the particle field. X-Ray diagnostics have been developed to penetrate the opacity of the flow, revealing the concentrations throughout the particle field as it expands and spreads downstream with time. Furthermore, an X-Ray particle tracking velocimetry diagnostic has been demonstrated to be feasible for this flow, which can be used to follow the trajectory of tracer particles seeded into the curtain. Additional experiments on single spherical particles accelerated behind an incident shock wave have shown that elevated particle drag coefficients can be attributed to increased compressibility rather than flow unsteadiness, clarifying confusing results from the historical database of shock tube

  8. Once-daily dose regimen of ribavirin is interchangeable with a twice-daily dose regimen: randomized open clinical trial

    Directory of Open Access Journals (Sweden)

    Balk JM

    2015-08-01

    Full Text Available Jiska M Balk,1 Guido RMM Haenen,1 Özgür M Koc,2 Ron Peters,3 Aalt Bast,1 Wim JF van der Vijgh,1 Ger H Koek,4 1Department of Toxicology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, 2Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, 3DSM Resolve, Geleen, 4Department of Internal Medicine, Division of Gastroenterology and Hepatology, Maastricht University Medical Centre, Maastricht, the Netherlands Background: The combination of ribavirin (RBV and pegylated interferon (PEG-IFN is effective in the treatment of chronic hepatitis C infection. Reducing the frequency of RBV intake from twice to once a day will improve compliance and opens up the opportunity to combine RBV with new and more specific direct-acting agents in one pill. Therefore, the purpose of this study was to evaluate the pharmacokinetic profile of RBV in a once-daily to twice-daily regimen. The secondary aim was to determine tolerability as well as the severity and differences in side effects of both treatment regimens. Methods: In this randomized open-label crossover study, twelve patients with chronic type 1 hepatitis C infection and weighing more than 75 kg were treated with 180 µg of PEG-IFN weekly and 1,200 mg RBV daily for 24 weeks. The patients received RBV dosed as 1,200 mg once-daily for 12 weeks followed by RBV dosed as 600 mg twice-daily for 12 weeks, or vice versa. In addition to the pharmacokinetic profile, the hematological profile and side effects were recorded. The RBV concentrations in plasma were determined using liquid chromatography-tandem mass spectrometry. Results: Eight of twelve patients completed the study. Neither the time taken for RBV to reach peak plasma concentration nor the AUC0-last (adjusted for difference in dose was significantly different between the two groups (P>0.05. Furthermore, the once-daily regimen did not give more side effects than the twice-daily regimen (P>0

  9. Comparison of different insulin regimens in elderly patients with NIDDM

    NARCIS (Netherlands)

    Wolffenbuttel, B H; Sels, J P; Rondas-Colbers, G J; Menheere, P P; Nieuwenhuijzen Kruseman, A C

    1996-01-01

    OBJECTIVE: To compare the metabolic effects of three different frequently used regimens of insulin administration on blood glucose control and serum lipids, and the costs associated with this treatment, in subjects with NIDDM, who were poorly controlled with oral antihyperglycemic agents. RESEARCH D

  10. Comparison of different insulin regimens in elderly patients with NIDDM

    NARCIS (Netherlands)

    Wolffenbuttel, B H; Sels, J P; Rondas-Colbers, G J; Menheere, P P; Nieuwenhuijzen Kruseman, A C

    1996-01-01

    OBJECTIVE: To compare the metabolic effects of three different frequently used regimens of insulin administration on blood glucose control and serum lipids, and the costs associated with this treatment, in subjects with NIDDM, who were poorly controlled with oral antihyperglycemic agents. RESEARCH D

  11. Outcomes of CAG Regimen for Refractory Biphenotypic Acute Leukemia Patients

    Institute of Scientific and Technical Information of China (English)

    Guang-sheng He; Xiang Zhang; De-pei Wu; Ai-ning Sun; Zheng-ming Jin; Hui-ying Qiu; Miao Miao; Xiao-wen Tang; Zheng-zheng Fu; Yue Han

    2009-01-01

    Objective To evaluated the efficiency of low-dose cytosine arabinoside plus aclarubicin with concurrent administration of granulocyte colony-stimulating factor(CAG)regimen for refractory biphenotypic acute leukemia(BAL).Methods We treated 5 refractory BAL patients by CAG regimen(10 mg·m 2 cytosine arabinoside subcutaneously administrated every 12 hours,day 1-14;5-7 mg·m2 aclarubicin intravenously administrated daily,day 1-8;and concurrently used 200 μg.m-2·d-1 granulocyte colony-stimulating factor subcutaneously)from November 2002 to April 2007.The efficacy of the regimen was evaluated by response rate,and the side effects were also measured.Results The complete remission rate was 80% ,median duration of absolute neutrophil count<5.0×108/L and platelet count<2.0×1010/L was day 13 and day 1,respectively;and the infection rate was low(Ⅲ-Ⅳ infection rate,20.00% ).Conclusion CAG regimen as remission induction chemotherapy for BAL patients is effective with a high remission rate and low toxicity.

  12. Tuberculous meningitis: is a 6-month treatment regimen sufficient?

    NARCIS (Netherlands)

    Loenhout-Rooyackers, J.H. van; Keyser, A.J.M.; Laheij, R.J.F.; Verbeek, A.L.M.; Meer, J.W.M. van der

    2001-01-01

    SETTING: The British Thoracic Society and the American Thoracic Society advise 12 months treatment for tuberculous meningitis, with at least isoniazid (H), rifampicin (R) and pyrazinamide (Z). OBJECTIVE: To establish whether a 6-month treatment regimen for tuberculous meningitis is equally as effect

  13. Are calcineurin inhibitors-free regimens ready for prime time?

    Science.gov (United States)

    Vincenti, Flavio

    2012-11-01

    The goal of research in transplant therapeutics is to achieve safe and effective immunosuppression strategies that allow durable engraftment free of toxicities. The calcineurin inhibitors (CNIs) regimens, because of their inherent toxicities (including nephrotoxicity), have been unable to meet these promises. Over the past decade acute cellular rejection decreased dramatically with a concomitant robust increase in 1-year graft survival; however, long-term graft outcome showed only modest improvement. This is due in part to the toxicities of the immunosuppressive drugs. The quest for a toxicity-free-CNI-free regimen has been both intense and frustrating. A turning point in CNIs-free therapy may have occurred with the recent approval of belatacept, which represents a new paradigm in immunosuppression: biological therapy for chronic immunosuppression devoid of the usual toxicities associated with the CNIs. Belatacept, a fusion receptor protein, blocks costimulation signals necessary for the activation of T cells. Although costimulation blockade has not been shown to induce tolerance, it can provide safe and effective immunosuppression without renal or cardiovascular toxicities. The approval of belatacept in both the United States and Europe for use in renal transplantation will finally push CNI-free regimens into prime time. Novel biologics such as ASKP1240 (a human anti-CD40 monoclonal antibody) and one small molecule, tofacitinib, may advance further the use of CNI-free regimens in organ transplantation.

  14. Gonzalez Regimen (PDQ®)—Health Professional Version

    Science.gov (United States)

    The Gonzalez regimen is a specialized diet that uses enzymes, supplements, and other factors in cancer management based on a theory that involves the use of pancreatic enzymes to help the body get rid of toxins that lead to cancer. Read about existing clinical data in this expert-reviewed summary.

  15. Efficacy of Some Combination Regimens of Oral Hypoglycaemic ...

    African Journals Online (AJOL)

    Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, 300001 Nigeria. All rights ... Hypoglycaemic Agents in Type 2 Diabetes Mellitus Patients ... levels induced by several OHA cobmination regimens were documented. ... highlighting the important benefits conferred by the use of multiple OHAs.

  16. High-Fidelity Micromechanics Model Enhanced for Multiphase Particulate Materials

    Science.gov (United States)

    Pindera, Marek-Jerzy; Arnold, Steven M.

    2003-01-01

    This 3-year effort involves the development of a comprehensive micromechanics model and a related computer code, capable of accurately estimating both the average response and the local stress and strain fields in the individual phases, assuming both elastic and inelastic behavior. During the first year (fiscal year 2001) of the investigation, a version of the model called the High-Fidelity Generalized Method of Cells (HFGMC) was successfully completed for the thermo-inelastic response of continuously reinforced multiphased materials with arbitrary periodic microstructures (refs. 1 and 2). The model s excellent predictive capability for both the macroscopic response and the microlevel stress and strain fields was demonstrated through comparison with exact analytical and finite element solutions. This year, HFGMC was further extended in two technologically significant ways. The first enhancement entailed the incorporation of fiber/matrix debonding capability into the two-dimensional version of HFGMC for modeling the response of unidirectionally reinforced composites such as titanium matrix composites, which exhibit poor fiber/matrix bond. Comparison with experimental data validated the model s predictive capability. The second enhancement entailed further generalization of HFGMC to three dimensions to enable modeling the response of particulate-reinforced (discontinuous) composites in the elastic material behavior domain. Next year, the three-dimensional version will be generalized to encompass inelastic effects due to plasticity, viscoplasticity, and damage, as well as coupled electromagnetothermomechanical (including piezoelectric) effects.

  17. Hybrid Explicit Residual Distribution Scheme for Compressible Multiphase Flows

    Science.gov (United States)

    Bacigaluppi, Paola; Abgrall, Rémi; Kaman, Tulin

    2017-03-01

    The aim of this work is the development of a fully explicit scheme in the framework of time dependent hyperbolic problems with strong interacting discontinuities to retain high order accuracy in the context of compressible multiphase flows. A new methodology is presented to compute compressible two-fluid problems applied to the five equation reduced model given in Kapila et al. (Physics of Fluids 2001). With respect to other contributions in that area, we investigate a method that provides mesh convergence to the exact solutions, where the studied non-conservative system is associated to consistent jump relations. The adopted scheme consists of a coupled predictor-corrector scheme, which follows the concept of residual distributions in Ricchiuto and Abgrall (J. Comp. Physics 2010), with a classical Glimm’s scheme (J. Sci. Stat. Comp. 1982) applied to the area where a shock is occurring. This numerical methodology can be easily extended to unstructured meshes. Test cases on a perfect gas for a two phase compressible flow on a Riemann problem have verified that the approximation converges to its exact solution. The results have been compared with the pure Glimm’s scheme and the expected exact solution, finding a good overlap.

  18. Modelling Galaxies with a 3d Multi-Phase ISM

    CERN Document Server

    Harfst, S; Hensler, G; Harfst, Stefan; Theis, Christian; Hensler, Gerhard

    2005-01-01

    We present a new particle code for modelling the evolution of galaxies. The code is based on a multi-phase description for the interstellar medium (ISM). We included star formation (SF), stellar feedback by massive stars and planetary nebulae, phase transitions and interactions between gas clouds and ambient diffuse gas, namely condensation, evaporation, drag and energy dissipation. The latter is realised by radiative cooling and inelastic cloud-cloud collisions. We present new schemes for SF and stellar feedback. They include a consistent calculation of the star formation efficiency (SFE) based on ISM properties as well as a detailed redistribution of the feedback energy into the different ISM phases. As a first test example we show a model of the evolution of a present day Milky-Way-type galaxy. Though the model exhibits a quasi-stationary behaviour in global properties like mass fractions or surface densities, the evolution of the ISM is locally strongly variable depending on the local SF and stellar feedb...

  19. Particle-in-cell method in multiphase flow simulations

    Science.gov (United States)

    Zhang, Duan; Zou, Qisu; Vanderheyden, Brian

    2004-11-01

    In many disperse multiphase flows there is of great interest to know the deformations and the possibility of break up of the grains of the disperse phase. Some examples are the pneumatic transport of agriculture grains and the fragment-gas-structure interaction in an explosion. In these examples one needs to consider the stress states in both the disperse phase and the continuous phase. The use of Eulerian method encounters significant difficulties associated with numerical diffusion. The use of Lagrangian method encounters mesh-tangling problem. Expensive re-meshing procedures need to be done frequently. The particle-in-cell method possesses advantages of both methods while avoids their difficulties. A grain of the disperse phase is represented by particles. A particle in the method is not only a Lagrangian marker; it carries mass, momentum, energy and other quantities associated with the grain. Although the particle-in-cell method was invented in the sixties, its recent developments significantly enhanced its capabilities. In this presentation, we outline basic principles and numerical schemes of the particle-in-cell method and then provide examples of its applications. This work is supported by the U.S. Department of Energy. (LA-UR-04-4177)

  20. On the predictive capabilities of multiphase Darcy flow models

    KAUST Repository

    Icardi, Matteo

    2016-01-09

    Darcy s law is a widely used model and the limit of its validity is fairly well known. When the flow is sufficiently slow and the porosity relatively homogeneous and low, Darcy s law is the homogenized equation arising from the Stokes and Navier- Stokes equations and depends on a single effective parameter (the absolute permeability). However when the model is extended to multiphase flows, the assumptions are much more restrictive and less realistic. Therefore it is often used in conjunction with empirical models (such as relative permeability and capillary pressure curves), derived usually from phenomenological speculations and experimental data fitting. In this work, we present the results of a Bayesian calibration of a two-phase flow model, using high-fidelity DNS numerical simulation (at the pore-scale) in a realistic porous medium. These reference results have been obtained from a Navier-Stokes solver coupled with an explicit interphase-tracking scheme. The Bayesian inversion is performed on a simplified 1D model in Matlab by using adaptive spectral method. Several data sets are generated and considered to assess the validity of this 1D model.

  1. Laser velocimeter measurements of multiphase flow of solids

    Energy Technology Data Exchange (ETDEWEB)

    Kadambi, J.R.; Chen, R.C.; Bhunia, S.

    1989-01-01

    A unique refractive index matched facility for studying solid-liquid multiphase flow has been developed. The refractive index matching of the solid and the liquid allows the use of non-intrusive Laser Doppler Velocimetry (LDV) to measure the solid and the liquid velocities. These measurements will be useful in developing a better understanding of solid-liquid flows, especially solid-liquid and solid-solid interactions. Silica gel and 50% sodium iodide solution in water (refractive index {approx}1.443) are used as the refractive index matched solid and liquid respectively. A two color back scatter mode LDV is used for making velocity measurements. Tests were conducted in solid-liquid slurries with volumetric solid concentration levels of 5% and 15% in the Reynolds number (Re) range of 400 to 9200. Silica gel particles of mean diameter 40 microns were used. Measurements included mapping of the solid and liquid velocities and obtaining the pressure drop data. Signal processing technique utilizing histogram of velocity measurements made at a point and signal amplitude discrimination was successfully used for differentiating between solid and liquid velocities. 34 refs., 61 figs., 5 tabs.

  2. A Statistical investigation of sloshing parameters for multiphase offshore separators

    Science.gov (United States)

    Mahmud, Md; Khan, Rafiqul; Xu, Qiang

    Liquid sloshing in multiphase offshore separators has been the subject of intense investigations for last several decades both by experiments and simulations. Large number scientists have worked to minimize sloshing impacts/intensity and some others have developed new methods to describe the sloshing patterns. In addition, complex mathematical models are developed to characterize sloshing phenomenon. However, a comprehensive statistical study of the input parameters and output results is not yet been studied. In this study, statistical approach will be considered to determine the significant parameters for liquid sloshing. The factor analysis and principal component analysis techniques are considered to identify the significant parameters for liquid sloshing. Numerical experiments are carried out through Computation Fluid Dynamics (CFD) technique using ANSYS Fluent software. The input parameters considered here are liquid depth/tank length ratio, tank acceleration, wave frequencies, amplitudes in various sea state conditions .The measured variables include hydrodynamic force, pressure, moments, turbulent kinetic energy, height of the free surface, vorticity. Mathematical correlations may be developed from the data analysis. Doctoral Candidate Dept of Chemical Engineering Lamar University, Beaumont, TX 77710.

  3. Improved quark coalescence for a multi-phase transport model

    Science.gov (United States)

    He, Yuncun; Lin, Zi-Wei

    2017-07-01

    The string melting version of a multi-phase transport model is often applied to high-energy heavy-ion collisions since the dense matter thus formed is expected to be in parton degrees of freedom. In this work we improve its quark coalescence component, which describes the hadronization of the partonic matter to a hadronic matter. We removed the previous constraint that forced the numbers of mesons, baryons, and antibaryons in an event to be separately conserved through the quark coalescence process. A quark now could form either a meson or a baryon depending on the distance to its coalescence partner(s). We then compare results from the improved model with the experimental data on hadron d N /d y ,pT spectra, and v2 in heavy-ion collisions from √{s NN}=62.4 GeV to 5.02 TeV. We show that, besides being able to describe these observables for low-pTpions and kaons, the improved model also better describes the low-p T baryon observables in general, especially the baryon p T spectra and antibaryon-to-baryon ratios for multistrange baryons.

  4. Initial partonic eccentricity fluctuations in a multiphase transport model

    Science.gov (United States)

    Ma, L.; Ma, G. L.; Ma, Y. G.

    2016-10-01

    Initial partonic eccentricities in Au+Au collisions at center-of-mass energy √{sN N}=200 GeV are investigated by using a multiphase transport model with a string-melting scenario. The initial eccentricities in different order of harmonics are studied by using participant and cumulant definitions. Eccentricity in terms of second-, fourth- and sixth-order cumulants as a function of number of participant nucleons are compared systematically with the traditional participant definition. The ratio of the cumulant eccentricities ɛ {4 }/ɛ {2 } and ɛ {6 }/ɛ {4 } are studied in comparison with the ratio of the corresponding flow harmonics. The conversion coefficients (vn/ɛn ) are explored up to fourth-order harmonics based on the cumulant method. Furthermore, studies on transverse momentum (pT) and pseudorapidity (η ) dependencies of eccentricities and their fluctuations are presented. As in ideal hydrodynamics, initial eccentricities are expected to be closely related to the final flow harmonics in relativistic heavy-ion collisions, studies of the fluctuating initial condition in the AMPT model will shed light on the tomography properties of the initial source geometry.

  5. Anisotropic distributions in a multi-phase transport model

    CERN Document Server

    Zhou, You; Feng, Zhao; Liu, Feng; Snellings, Raimond

    2015-01-01

    With A Multi-Phase Transport (AMPT) model we investigate the relation between the magnitude, fluctuations and correlations of the initial state spatial anisotropy $\\varepsilon_{n}$ and the final state anisotropic flow coefficients $v_{n}$ in Au+Au collisions at $\\sqrt{s_{_{\\rm NN}}}=$ 200 GeV. It is found that the relative eccentricity fluctuations in AMPT account for the observed elliptic flow fluctuations, in agreement with measurements of the STAR collaboration. In addition, the studies based on 2- and multi-particle correlations and event-by-event distributions of the anisotropies suggest that the Elliptic-Power function is a promising candidate of the underlying probability density function of the event-by-event distributions of $\\varepsilon_{n}$ as well as $v_{n}$. Furthermore, the correlations between different order symmetry planes and harmonics in the initial coordinate space and final state momentum space are presented. Non-zero values of these correlations have been observed. The comparison between...

  6. Black hole feedback in a multiphase interstellar medium

    CERN Document Server

    Bourne, Martin A; Hobbs, Alexander

    2014-01-01

    Ultrafast outflows (UFOs) from supermassive black holes (SMBHs) are thought to regulate the growth of SMBHs and host galaxies, resulting in a number of observational correlations. We present high-resolution numerical simulations of the impact of a thermalized UFO on the ambient gas in the inner part of the host galaxy. Our results depend strongly on whether the gas is homogeneous or clumpy. In the former case all of the ambient gas is driven outward rapidly as expected based on commonly used energy budget arguments, while in the latter the flows of mass and energy decouple. Carrying most of the energy, the shocked UFO escapes from the bulge via paths of least resistance, taking with it only the low-density phase of the host. Most of the mass is however in the high-density phase, and is affected by the UFO much less strongly, and may even continue to flow inwards. We suggest that the UFO energy leakage through the pores in the multiphase interstellar medium (ISM) may explain why observed SMBHs are so massive d...

  7. Impact of nongray multiphase radiation in pulverized coal combustion

    Science.gov (United States)

    Roy, Somesh; Wu, Bifen; Modest, Michael; Zhao, Xinyu

    2016-11-01

    Detailed modeling of radiation is important for accurate modeling of pulverized coal combustion. Because of high temperature and optical properties, radiative heat transfer from coal particles is often more dominant than convective heat transfer. In this work a multiphase photon Monte Carlo radiation solver is used to investigate and to quantify the effect of nongray radiation in a laboratory-scale pulverized coal flame. The nongray radiative properties of carrier phase (gas) is modeled using HITEMP database. Three major species - CO, CO2, and H2O - are treated as participating gases. Two optical models are used to evaluate radiative properties of coal particles: a formulation based on the large particle limit and a size-dependent correlation. Effect of scattering due to coal particle is also investigated using both isotropic scattering and anisotropic scattering using a Henyey-Greenstein function. Lastly, since the optical properties of ash is very different from that of coal, the effect of ash content on the radiative properties of coal particle is examined. This work used Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant Number ACI-1053575.

  8. Unsteady RANS and Large Eddy simulations of multiphase diesel injection

    Science.gov (United States)

    Philipp, Jenna; Green, Melissa; Akih-Kumgeh, Benjamin

    2015-11-01

    Unsteady Reynolds Averaged Navier-Stokes (URANS) and Large Eddy Simulations (LES) of two-phase flow and evaporation of high pressure diesel injection into a quiescent, high temperature environment is investigated. Unsteady RANS and LES are turbulent flow simulation approaches used to determine complex flow fields. The latter allows for more accurate predictions of complex phenomena such as turbulent mixing and physio-chemical processes associated with diesel combustion. In this work we investigate a high pressure diesel injection using the Euler-Lagrange method for multiphase flows as implemented in the Star-CCM+ CFD code. A dispersed liquid phase is represented by Lagrangian particles while the multi-component gas phase is solved using an Eulerian method. Results obtained from the two approaches are compared with respect to spray penetration depth and air entrainment. They are also compared with experimental data taken from the Sandia Engine Combustion Network for ``Spray A''. Characteristics of primary and secondary atomization are qualitatively evaluated for all simulation modes.

  9. Dynamic dielectrophoresis model of multi-phase ionic fluids.

    Directory of Open Access Journals (Sweden)

    Ying Yan

    Full Text Available Ionic-based dielectrophoretic microchips have attracted significant attention due to their wide-ranging applications in electro kinetic and biological experiments. In this work, a numerical method is used to simulate the dynamic behaviors of ionic droplets in a microchannel under the effect of dielectrophoresis. When a discrete liquid dielectric is encompassed within a continuous fluid dielectric placed in an electric field, an electric force is produced due to the dielectrophoresis effect. If either or both of the fluids are ionic liquids, the magnitude and even the direction of the force will be changed because the net ionic charge induced by an electric field can affect the polarization degree of the dielectrics. However, using a dielectrophoresis model, assuming ideal dielectrics, results in significant errors. To avoid the inaccuracy caused by the model, this work incorporates the electrode kinetic equation and defines a relationship between the polarization charge and the net ionic charge. According to the simulation conditions presented herein, the electric force obtained in this work has an error exceeding 70% of the actual value if the false effect of net ionic charge is not accounted for, which would result in significant issues in the design and optimization of experimental parameters. Therefore, there is a clear motivation for developing a model adapted to ionic liquids to provide precise control for the dielectrophoresis of multi-phase ionic liquids.

  10. A double inclusion model for multiphase piezoelectric composites

    Science.gov (United States)

    Lin, Yirong; Sodano, Henry A.

    2010-03-01

    A novel active structural fiber (ASF; Lin and Sodano 2008 Compos. Sci. Technol. 68 1911-8) was developed that can be embedded in a composite material in order to perform sensing and actuation, in addition to providing load bearing functionality. In order to fully understand the electroelastic properties of the material, this paper will introduce a three-dimensional micromechanics model for estimating the effective electroelastic properties of the multifunctional composites with different design parameters. The three-dimensional model is formulated by extending the double inclusion model to multiphase composites with piezoelectric constituents. The double inclusion model has been chosen for the ASF studied here because it is designed to model composites reinforced by inclusions with multilayer coatings. The accuracy of our extended double inclusion model will be evaluated through a three-dimensional finite element analysis of a representative volume element of the ASF composite. The results will demonstrate that the micromechanics model developed here can very accurately predict the electroelastic properties of the multifunctional composites.

  11. Multiphase Signatures of AGN Feedback in Abell 2597

    CERN Document Server

    Tremblay, G R; Baum, S A; Clarke, T E; Sarazin, C L; Bregman, J N; Combes, F; Donahue, M; Edge, A C; Fabian, A C; Ferland, G J; McNamara, B R; Mittal, R; Oonk, J B R; Quillen, A C; Russell, H R; Sanders, J S; Salomé, P; Voit, G M; Wilman, R J; Wise, M W

    2012-01-01

    We present new Chandra X-ray observations of the brightest cluster galaxy (BCG) in the cool core cluster Abell 2597. The data reveal an extensive kpc-scale X-ray cavity network as well as a 15 kpc filament of soft-excess gas exhibiting strong spatial correlation with archival VLA radio data. In addition to several possible scenarios, multiwavelength evidence may suggest that the filament is associated with multiphase (10^3 - 10^7 K) gas that has been entrained and dredged-up by the propagating radio source. Stemming from a full spectral analysis, we also present profiles and 2D spectral maps of modeled X-ray temperature, entropy, pressure, and metal abundance. The maps reveal an arc of hot gas which in projection borders the inner edge of a large X-ray cavity. Although limited by strong caveats, we suggest that the hot arc may be (a) due to a compressed rim of cold gas pushed outward by the radio bubble or (b) morphologically and energetically consistent with cavity-driven active galactic nucleus (AGN) heatin...

  12. Multiphasic strain differentiation of atypical mycobacteria from elephant trunk wash.

    Science.gov (United States)

    Chan, Kok-Gan; Loke, Mun Fai; Ong, Bee Lee; Wong, Yan Ling; Hong, Kar Wai; Tan, Kian Hin; Kaur, Sargit; Ng, Hien Fuh; Abdul Razak, Mfa; Ngeow, Yun Fong

    2015-01-01

    Background. Two non-tuberculous mycobacterial strains, UM_3 and UM_11, were isolated from the trunk wash of captive elephants in Malaysia. As they appeared to be identical phenotypes, they were investigated further by conventional and whole genome sequence-based methods of strain differentiation. Methods. Multiphasic investigations on the isolates included species identification with hsp65 PCR-sequencing, conventional biochemical tests, rapid biochemical profiling using API strips and the Biolog Phenotype Microarray analysis, protein profiling with liquid chromatography-mass spectrometry, repetitive sequence-based PCR typing and whole genome sequencing followed by phylogenomic analyses. Results. The isolates were shown to be possibly novel slow-growing schotochromogens with highly similar biological and genotypic characteristics. Both strains have a genome size of 5.2 Mbp, G+C content of 68.8%, one rRNA operon and 52 tRNAs each. They qualified for classification into the same species with their average nucleotide identity of 99.98% and tetranucleotide correlation coefficient of 0.99999. At the subspecies level, both strains showed 98.8% band similarity in the Diversilab automated repetitive sequence-based PCR typing system, 96.2% similarity in protein profiles obtained by liquid chromatography mass spectrometry, and a genomic distance that is close to zero in the phylogenomic tree constructed with conserved orthologs. Detailed epidemiological tracking revealed that the elephants shared a common habitat eight years apart, thus, strengthening the possibility of a clonal relationship between the two strains.

  13. Oxytocin Regimen for Labor Augmentation, Labor Progression, Perinatal Outcomes

    Science.gov (United States)

    Zhang, Jun; Branch, D. Ware; Ramirez, Mildred M.; Laughon, S. Katherine; Reddy, Uma; Hoffman, Mathew; Bailit, Jennifer; Kominiarek, Michelle; Chen, Zhen; Hibbard, Judith U.

    2013-01-01

    Objective To examine the effects and safety of high-dose (compared with low-dose) oxytocin regimen for labor augmentation on perinatal outcomes. Methods Data from the Consortium on Safe Labor were used. A total of 15,054 women from six hospitals were eligible for the analysis. Women were grouped based on their oxytocin starting dose and incremental dosing: 1, 2, and 4 mU/min. Duration of labor and a number of maternal and neonatal outcomes were compared among these three groups stratified by parity. Multivariable logistic regression and generalized linear mixed model were used to adjust for potential confounders. Results Oxytocin regimen did not affect the rate of cesarean delivery or other perinatal outcomes. Compared to 1 mU/min, the regimens starting with 2 mU/min and 4 mU/min reduced the duration of 1st stage by 0.8 hours (95% confidence interval 0.5 – 1.1) and 1.3 hours (1.0 – 1.7), respectively, in nulliparas. No effect was observed on the second stage of labor. Similar patterns were observed in multiparas. High-dose regimen was associated with a reduced risk of meconium stain, chorioamnionitis, and newborn fever in multiparas. Conclusion High-dose oxytocin regimen (starting dose at 4 mU/min and increment of 4 mU/min) is associated with a shorter duration of first stage of labor in all parities without increasing the cesarean delivery rate or adversely affecting perinatal outcomes. PMID:21775839

  14. Modeling and Simulation of Pore Scale Multiphase Fluid Flow and Reactive Transport in Fractured and Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Paul Meakin; Alexandre Tartakovsky

    2009-07-01

    In the subsurface fluids play a critical role by transporting dissolved minerals, colloids and contaminants (sometimes over long distances), by mediating dissolution and precipitation processes and enabling chemical transformations in solution and at mineral surfaces. Although the complex geometries of fracture apertures, fracture networks and pore spaces may make it difficult to accurately predict fluid flow in saturated (single-phase) subsurface systems, well developed methods are available. The simulation of multiphase fluid flow in the subsurface is much more challenging because of the large density and/or viscosity ratios found in important applications (water/air in the vadose zone, water/oil, water/gas, gas/oil and water/oil/gas in oil reservoirs, water/air/non-aqueous phase liquids (NAPL) in contaminated vadose zone systems and gas/molten rock in volcanic systems, for example). In addition, the complex behavior of fluid-fluid-solid contact lines, and its impact on dynamic contact angles, must also be taken into account, and coupled with the fluid flow. Pore network models and simple statistical physics based models such as the invasion percolation and diffusion-limited aggregation models have been used quite extensively. However, these models for multiphase fluid flow are based on simplified models for pore space geometries and simplified physics. Other methods such a lattice Boltzmann and lattice gas models, molecular dynamics, Monte Carlo methods, and particle methods such as dissipative particle dynamics and smoothed particle hydrodynamics are based more firmly on first principles, and they do not require simplified pore and/or fracture geometries. However, they are less (in some cases very much less) computationally efficient that pore network and statistical physics models. Recently a combination of continuum computation fluid dynamics, fluid-fluid interface tracking or capturing and simple models for the dependence of contact angles on fluid velocity

  15. Modeling and simulation of pore-scale multiphase fluid flow and reactive transport in fractured and porous media

    Energy Technology Data Exchange (ETDEWEB)

    Meakin, Paul; Tartakovsky, Alexandre M.

    2009-01-01

    In the subsurface fluids play a critical role by transporting dissolved minerals, colloids and contaminants (sometimes over long distances), by mediating dissolution and precipitation processes and enabling chemical transformations in solution and at mineral surfaces. Although the complex geometries of fracture apertures, fracture networks and pore spaces may make it difficult to accurately predict fluid flow in saturated (single-phase) subsurface systems, well developed methods are available. The simulation of multiphase fluid flow in the subsurface is much more challenging because of the large density and/or viscosity ratios found in important applications (water/air in the vadose zone, water/oil, water/gas, gas/oil and water/oil/gas in oil reservoirs, water/air/non-aqueous phase liquids (NAPL) in contaminated vadose zone systems and gas/molten rock in volcanic systems, for example). In addition, the complex behavior of fluid-fluid-solid contact lines, and its impact on dynamic contact angles, must also be taken into account, and coupled with the fluid flow. Pore network models and simple statistical physics based models such as the invasion percolation and diffusion-limited aggregation models have been used quite extensively. However, these models for multiphase fluid flow are based on simplified models for pore space geometries and simplified physics. Other methods such a lattice Boltzmann and lattice gas models, molecular dynamics, Monte Carlo methods, and particle methods such as dissipative particle dynamics and smoothed particle hydrodynamics are based more firmly on first principles, and they do not require simplified pore and/or fracture geometries. However, they are less (in some cases very much less) computationally efficient that pore network and statistical physics models. Recently a combination of continuum computation fluid dynamics, fluid-fluid interface tracking or capturing and simple models for the dependence of contact angles on fluid velocity

  16. Structured reporting of multiphasic CT for pancreatic cancer: potential effect on staging and surgical planning.

    Science.gov (United States)

    Brook, Olga R; Brook, Alexander; Vollmer, Charles M; Kent, Tara S; Sanchez, Norberto; Pedrosa, Ivan

    2015-02-01

    To compare structured versus nonstructured reporting of multiphasic computed tomography (CT) for staging of pancreatic cancer and the effects of both types of reporting on subjective assessment of resectability. This institutional review board-approved, HIPAA-compliant retrospective study with waiver of informed consent included all patients who were referred for presurgical multiphasic CT of the pancreas between December 2006 and April 2011 at one institution before and after implementation (April 2008) of a structured reporting template. The template was created specifically for reporting multiphasic CT results to stage pancreatic cancer in patients and contained specific information relevant to surgical and oncologic planning. Multiphasic CT reports were assessed for the presence of 12 key features required for staging and surgical planning, including location, size, enhancement, node status, and vascular involvement. Three pancreatic surgeons evaluated the reports to assess resectability, surgical planning, and ease of extracting information before and after reviewing the multiphasic CT images blinded to the patient identifiers. The Student t test and χ(2) test were used for statistical analysis. Forty-eight (40%) structured and 72 (60%) nonstructured multiphasic CT reports were reviewed. Nonstructured reports contained a mean ± standard deviation of 7.3 key features ± 2.1 (range, 1-11) and structured reports contained 10.6 ± 0.9 (range, 9-12) features (P planning was deemed easily accessible in 94%, 60%, and 98% of structured and 47%, 54%, and 32% of nonstructured reports by the three surgeons, respectively (P planning in 96%, 69%, and 98% of structured and 31%, 43%, and 25% of nonstructured reports (P planning. Surgeons were more confident regarding decisions about tumor resectability when they reviewed structured reports before review of multiphasic CT images. © RSNA, 2014.

  17. Comparing cluster-level dynamic treatment regimens using sequential, multiple assignment, randomized trials: Regression estimation and sample size considerations.

    Science.gov (United States)

    NeCamp, Timothy; Kilbourne, Amy; Almirall, Daniel

    2017-08-01

    Cluster-level dynamic treatment regimens can be used to guide sequential treatment decision-making at the cluster level in order to improve outcomes at the individual or patient-level. In a cluster-level dynamic treatment regimen, the treatment is potentially adapted and re-adapted over time based on changes in the cluster that could be impacted by prior intervention, including aggregate measures of the individuals or patients that compose it. Cluster-randomized sequential multiple assignment randomized trials can be used to answer multiple open questions preventing scientists from developing high-quality cluster-level dynamic treatment regimens. In a cluster-randomized sequential multiple assignment randomized trial, sequential randomizations occur at the cluster level and outcomes are observed at the individual level. This manuscript makes two contributions to the design and analysis of cluster-randomized sequential multiple assignment randomized trials. First, a weighted least squares regression approach is proposed for comparing the mean of a patient-level outcome between the cluster-level dynamic treatment regimens embedded in a sequential multiple assignment randomized trial. The regression approach facilitates the use of baseline covariates which is often critical in the analysis of cluster-level trials. Second, sample size calculators are derived for two common cluster-randomized sequential multiple assignment randomized trial designs for use when the primary aim is a between-dynamic treatment regimen comparison of the mean of a continuous patient-level outcome. The methods are motivated by the Adaptive Implementation of Effective Programs Trial which is, to our knowledge, the first-ever cluster-randomized sequential multiple assignment randomized trial in psychiatry.

  18. Rheological flow laws for multiphase magmas: An empirical approach

    Science.gov (United States)

    Pistone, Mattia; Cordonnier, Benoît; Ulmer, Peter; Caricchi, Luca

    2016-07-01

    The physical properties of magmas play a fundamental role in controlling the eruptive dynamics of volcanoes. Magmas are multiphase mixtures of crystals and gas bubbles suspended in a silicate melt and, to date, no flow laws describe their rheological behaviour. In this study we present a set of equations quantifying the flow of high-viscosity (> 105 Pa·s) silica-rich multiphase magmas, containing both crystals (24-65 vol.%) and gas bubbles (9-12 vol.%). Flow laws were obtained using deformation experiments performed at high temperature (673-1023 K) and pressure (200-250 MPa) over a range of strain-rates (5 · 10- 6 s- 1 to 4 · 10- 3 s- 1), conditions that are relevant for volcanic conduit processes of silica-rich systems ranging from crystal-rich lava domes to crystal-poor obsidian flows. We propose flow laws in which stress exponent, activation energy, and pre-exponential factor depend on a parameter that includes the volume fraction of weak phases (i.e. melt and gas bubbles) present in the magma. The bubble volume fraction has opposing effects depending on the relative crystal volume fraction: at low crystallinity bubble deformation generates gas connectivity and permeability pathways, whereas at high crystallinity bubbles do not connect and act as "lubricant" objects during strain localisation within shear bands. We show that such difference in the evolution of texture is mainly controlled by the strain-rate (i.e. the local stress within shear bands) at which the experiments are performed, and affect the empirical parameters used for the flow laws. At low crystallinity ( 44 vol.%) the viscosity decreases with increasing strain-rate. Because these behaviours are also associated with modifications of sample textures during the experiment and, thus, are not purely the result of different deformation rates, we refer to "apparent shear-thickening" and "apparent shear-thinning" for the behaviours observed at low and high crystallinity, respectively. At low

  19. Multiphasic modification of intrinsic functional connectivity of the rat brain during increasing levels of propofol.

    Science.gov (United States)

    Liu, Xiping; Pillay, Siveshigan; Li, Rupeng; Vizuete, Jeannette A; Pechman, Kimberly R; Schmainda, Kathleen M; Hudetz, Anthony G

    2013-12-01

    The dose-dependent effects of anesthetics on brain functional connectivity are incompletely understood. Resting-state functional magnetic resonance imaging (rsfMRI) is widely used to assess the functional connectivity in humans and animals. Propofol is an anesthetic agent with desirable characteristics for functional neuroimaging in animals but its dose-dependent effects on rsfMRI functional connectivity have not been determined. Here we tested the hypothesis that brain functional connectivity undergoes specific changes in distinct neural networks at anesthetic depths associated with loss of consciousness. We acquired spontaneous blood oxygen level-dependent (BOLD) signals simultaneously with electroencephalographic (EEG) signals from rats under steady-state, intravenously administered propofol at increasing doses from light sedation to deep anesthesia (20, 40, 60, 80, and 100 mg/kg/h IV). Power spectra and burst suppression ratio were calculated from the EEG to verify anesthetic depth. Functional connectivity was determined from the whole brain correlation of BOLD data in regions of interest followed by a segmentation of the correlation maps into anatomically defined regional connectivity. We found that propofol produced multiphasic, dose dependent changes in functional connectivity of various cortical and subcortical networks. Cluster analysis predicted segregation of connectivity into two cortical and two subcortical clusters. In one cortical cluster (somatosensory and parietal), the early reduction in connectivity was followed by transient reversal; in the other cluster (sensory, motor and cingulate/retrosplenial), this rebound was absent. The connectivity of the subcortical cluster (brainstem, hippocampal and caudate) was strongly reduced, whereas that of another (hypothalamus, medial thalamus and n. basalis) did not. Subcortical connectivity increased again in deep anesthesia associated with EEG burst suppression. Regional correlation analysis confirmed the

  20. Subsurface Multiphase Flow and Multicomponent Reactive Transport Modeling using High-Performance Computing

    Energy Technology Data Exchange (ETDEWEB)

    Hammond, Glenn E.; Lichtner, Peter C.; Lu, Chuan

    2007-08-01

    Numerical modeling has become a critical tool to the Department of Energy for evaluating the environmental impact of alternative energy sources and remediation strategies for legacy waste sites. Unfortunately, the physical and chemical complexity of many sites overwhelms the capabilities of even most “state of the art” groundwater models. Of particular concern are the representation of highly-heterogeneous stratified rock/soil layers in the subsurface and the biological and geochemical interactions of chemical species within multiple fluid phases. Clearly, there is a need for higher-resolution modeling (i.e. more spatial, temporal, and chemical degrees of freedom) and increasingly mechanistic descriptions of subsurface physicochemical processes. We present research being performed in the development of PFLOTRAN, a parallel multiphase flow and multicomponent reactive transport model. Written in Fortran90, PFLOTRAN is founded upon PETSc data structures and solvers and has exhibited impressive strong scalability on up to 4000 processors on the ORNL Cray XT3. We are employing PFLOTRAN in the simulation of uranium transport at the Hanford 300 Area, a contaminated site of major concern to the Department of Energy, the State of Washington, and other government agencies where overly-simplistic historical modeling erroneously predicted decade removal times for uranium by ambient groundwater flow. By leveraging the billions of degrees of freedom available through high-performance computation using tens of thousands of processors, we can better characterize the release of uranium into groundwater and its subsequent transport to the Columbia River, and thereby better understand and evaluate the effectiveness of various proposed remediation strategies.

  1. PREFACE: The 6th International Symposium on Measurement Techniques for Multiphase Flows

    Science.gov (United States)

    Okamoto, Koji; Murai, Yuichi

    2009-02-01

    Research on multi-phase flows is very important for industrial applications, including power stations, vehicles, engines, food processing, and so on. Also, from the environmental viewpoint, multi-phase flows need to be investigated to overcome global warming. Multi-phase flows originally have non-linear features because they are multi-phased. The interaction between the phases plays a very interesting role in the flows. The non-linear interaction causes the multi-phase flows to be very difficult to understand phenomena. The International Symposium on Measurement Techniques for Multi-phase Flows (ISMTMF) is a unique symposium. The target of the symposium is to exchange the state-of-the-art knowledge on the measurement techniques for non-linear multi-phase flows. Measurement technique is the key technology to understanding non-linear phenomena. The ISMTMF began in 1995 in Nanjing, China. The symposium has continuously been held every two or three years. The ISMTMF-2008 was held in Okinawa, Japan as the 6th symposium of ISMTMF on 15-17 December 2008. Okinawa has a long history as the Ryukyus Kingdom. China and Japan have had cultural and economic exchanges through Okinawa for more than 1000 years. Please enjoy Okinawa and experience its history to enhance our international communication. The present symposium was attended by 124 participants, the program included 107 contributions with 5 plenary lectures, 2 keynote lectures, and 100 oral regular paper presentations. The topics include, besides the ordinary measurement techniques for multiphase flows, acoustic and electric sensors, bubbles and microbubbles, computed tomography, gas-liquid interface, laser-imaging and PIV, oil/coal/drop and spray, solid and powder, spectral and multi-physics. This volume includes the presented papers at ISMTMF-2008. In addition to this volume, ten selected papers will be published in a special issue of Measurement Science and Technology. We would like to express special thanks to all

  2. Multiphasic strain differentiation of atypical mycobacteria from elephant trunk wash

    Directory of Open Access Journals (Sweden)

    Kok-Gan Chan

    2015-11-01

    Full Text Available Background. Two non-tuberculous mycobacterial strains, UM_3 and UM_11, were isolated from the trunk wash of captive elephants in Malaysia. As they appeared to be identical phenotypes, they were investigated further by conventional and whole genome sequence-based methods of strain differentiation.Methods. Multiphasic investigations on the isolates included species identification with hsp65 PCR-sequencing, conventional biochemical tests, rapid biochemical profiling using API strips and the Biolog Phenotype Microarray analysis, protein profiling with liquid chromatography-mass spectrometry, repetitive sequence-based PCR typing and whole genome sequencing followed by phylogenomic analyses.Results. The isolates were shown to be possibly novel slow-growing schotochromogens with highly similar biological and genotypic characteristics. Both strains have a genome size of 5.2 Mbp, G+C content of 68.8%, one rRNA operon and 52 tRNAs each. They qualified for classification into the same species with their average nucleotide identity of 99.98% and tetranucleotide correlation coefficient of 0.99999. At the subspecies level, both strains showed 98.8% band similarity in the Diversilab automated repetitive sequence-based PCR typing system, 96.2% similarity in protein profiles obtained by liquid chromatography mass spectrometry, and a genomic distance that is close to zero in the phylogenomic tree constructed with conserved orthologs. Detailed epidemiological tracking revealed that the elephants shared a common habitat eight years apart, thus, strengthening the possibility of a clonal relationship between the two strains.

  3. Multiphase modelling of vascular tumour growth in two spatial dimensions

    KAUST Repository

    Hubbard, M.E.

    2013-01-01

    In this paper we present a continuum mathematical model of vascular tumour growth which is based on a multiphase framework in which the tissue is decomposed into four distinct phases and the principles of conservation of mass and momentum are applied to the normal/healthy cells, tumour cells, blood vessels and extracellular material. The inclusion of a diffusible nutrient, supplied by the blood vessels, allows the vasculature to have a nonlocal influence on the other phases. Two-dimensional computational simulations are carried out on unstructured, triangular meshes to allow a natural treatment of irregular geometries, and the tumour boundary is captured as a diffuse interface on this mesh, thereby obviating the need to explicitly track the (potentially highly irregular and ill-defined) tumour boundary. A hybrid finite volume/finite element algorithm is used to discretise the continuum model: the application of a conservative, upwind, finite volume scheme to the hyperbolic mass balance equations and a finite element scheme with a stable element pair to the generalised Stokes equations derived from momentum balance, leads to a robust algorithm which does not use any form of artificial stabilisation. The use of a matrix-free Newton iteration with a finite element scheme for the nutrient reaction-diffusion equations allows full nonlinearity in the source terms of the mathematical model.Numerical simulations reveal that this four-phase model reproduces the characteristic pattern of tumour growth in which a necrotic core forms behind an expanding rim of well-vascularised proliferating tumour cells. The simulations consistently predict linear tumour growth rates. The dependence of both the speed with which the tumour grows and the irregularity of the invading tumour front on the model parameters is investigated. © 2012 Elsevier Ltd.

  4. Multiphase hydrodechlorination of polychlorinated aromatics - Towards scale-up.

    Science.gov (United States)

    Perosa, Alvise; Selva, Maurizio; Maschmeyer, Thomas

    2017-04-01

    We describe a chemical technology for the reductive catalytic multiphase hydrodechlorination (HDC) of chlorinated aromatics to greatly reduce their toxicity and aid the disposal of such species. The system requires no solvent and the catalyst displays a high recycling efficiency. In the present case, 1,3-dichlorobenzene (1,3-DCB) was used as a model compound, and was quantitatively hydrodechlorinated to benzene with hydrogen, in a tri-phasic liquid system consisting of the chlorinated aromatic itself as the top organic phase, an aqueous sodium hydroxide bottom phase (that neutralises acids formed), and an Aliquat(®)336 (A336) intermediate phase containing a Pd/C catalyst. Once the reaction was complete the top phase (now just benzene) and the bottom phase (now principally aqueous NaCl) were removed and the remaining catalytic A336/(Pd/C) phase recycled. This model study was conducted on a multi-gram scale with a view of demonstrating its applicability to the detoxification of PCBs. Comparison of the Mass Intensity (MI) and turnover frequency (TOF) of our model reaction with three examples of published procedures for the HDC of DCB, indicated that the MI for our system (MI = 6.33) was lower by an order of magnitude or more than that of the others (MI = 27.9, 64.6, 96016), and that TOFs were comparable. A preliminary cost analysis indicates approximately 2000 €/tonne to treat tonne-scale amounts of chlorinated aromatics, making the system in principle useful for industrial implementation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. [Spectral diagnosis of hydroxyl radical in multiphase pulsed discharge system].

    Science.gov (United States)

    Wang, Hui-juan; Li, Jie; Quan, Xie; Wu, Yan; Li, Guo-feng

    2007-12-01

    A gas-liquid hybrid pulsed discharge system with a multi-needle-to-plate electrode geometry was used in the present study. A multiphase (gas-liquid-solid) pulsed discharge system was then formed by adding glasses beads immobilized with TiO2 photocatalyst into the discharge system. In the present paper, ultraviolet light produced during the pulsed discharge process was used as the lamp-house to induce the photocatalytic activity of the TiO2 photocatalyst. The synergistic effect of pulsed discharge and TiO2 photocatalysis was reviewed by the spectral diagnosis of hydroxyl radical ( *OH) in the pulsed discharge system. The obtained results showed that the emission spectrum of *OH could be observed at 306 nm (A2Sigma+-->X2II), 309 mn (A2Sigma+ (v' = 0) --> X2II (v" = 0)) and 313 nm (A2Sigma+ (v' = 1) --> X2II (v" = 1) transition). The relative emission intensity of *OH at 313 nm in the discharge system was the strongest among the three characteristic spectra. The relative emission intensity of *OH at 313 nm was stronger by adding TiO2 photocatalyst into the pulsed discharge system than that in the sole pulsed discharge system. In the case of experiments that changing the gas bubbling varieties and initial solution pH values, the results revealed that the relative emission intensity of *OH at 313 nm in the synergistic system was stronger when Ar was used as bubbling gas compared with that when air and oxygen were bubbled into the reaction system. Furthermore, the acidic solution system was favorable for producing more *OH, and therefore the corresponding emission intensity of *OH at 313 nm was stronger than that in the neutral and basic solution.

  6. Multi-phase volcanic resurfacing at Loki Patera on Io

    Science.gov (United States)

    de Kleer, K.; Skrutskie, M.; Leisenring, J.; Davies, A. G.; Conrad, A.; de Pater, I.; Resnick, A.; Bailey, V.; Defrère, D.; Hinz, P.; Skemer, A.; Spalding, E.; Vaz, A.; Veillet, C.; Woodward, C. E.

    2017-05-01

    The Jovian moon Io hosts the most powerful persistently active volcano in the Solar System, Loki Patera. The interior of this volcanic, caldera-like feature is composed of a warm, dark floor covering 21,500 square kilometres surrounding a much cooler central ‘island’. The temperature gradient seen across areas of the patera indicates a systematic resurfacing process, which has been seen to occur typically every one to three years since the 1980s. Analysis of past data has indicated that the resurfacing progressed around the patera in an anti-clockwise direction at a rate of one to two kilometres per day, and that it is caused either by episodic eruptions that emplace voluminous lava flows or by a cyclically overturning lava lake contained within the patera. However, spacecraft and telescope observations have been unable to map the emission from the entire patera floor at sufficient spatial resolution to establish the physical processes at play. Here we report temperature and lava cooling age maps of the entire patera floor at a spatial sampling of about two kilometres, derived from ground-based interferometric imaging of thermal emission from Loki Patera obtained on 8 March 2015 UT as the limb of Europa occulted Io. Our results indicate that Loki Patera is resurfaced by a multi-phase process in which two waves propagate and converge around the central island. The different velocities and start times of the waves indicate a non-uniformity in the lava gas content and/or crust bulk density across the patera.

  7. An origin for multiphase gas in galactic winds and haloes

    Science.gov (United States)

    Thompson, Todd A.; Quataert, Eliot; Zhang, Dong; Weinberg, David H.

    2016-01-01

    The physical origin of high-velocity cool gas seen in galactic winds remains unknown. Following work by B. Wang, we argue that radiative cooling in initially hot thermally-driven outflows can produce fast neutral atomic and photoionized cool gas. The inevitability of adiabatic cooling from the flow's initial 107-108 K temperature and the shape of the cooling function for T ≲ 107 K imply that outflows with hot gas mass-loss rate relative to star formation rate of β =dot{M}_hot/dot{M}_star ≳ 0.5 cool radiatively on scales ranging from the size of the energy injection region to tens of kpc. We highlight the β and star formation rate surface density dependence of the column density, emission measure, radiative efficiency, and velocity. At rcool, the gas produces X-ray and then UV/optical line emission with a total power bounded by ˜10-2 L⋆ if the flow is powered by steady-state star formation with luminosity L⋆. The wind is thermally unstable at rcool, potentially leading to a multiphase medium. Cooled winds decelerate significantly in the extended gravitational potential of galaxies. The cool gas precipitated from hot outflows may explain its prevalence in galactic haloes. We forward a picture of winds whereby cool clouds are initially accelerated by the ram pressure of the hot flow, but are rapidly shredded by hydrodynamical instabilities, thereby increasing β, seeding radiative and thermal instability, and cool gas rebirth. If the cooled wind shocks as it sweeps up the circumgalactic medium, its cooling time is short, thus depositing cool gas far out into the halo. Finally, conduction can dominate energy transport in low-β hot winds, leading to flatter temperature profiles than otherwise expected, potentially consistent with X-ray observations of some starbursts.

  8. Damage characterization of high-strength multiphase steels

    Science.gov (United States)

    Heibel, S.; Nester, W.; Clausmeyer, T.; Tekkaya, A. E.

    2016-11-01

    High-strength steels show an entirely different material behavior than conventional deep-drawing steels. This fact is caused among others by the multiphase nature of their structure. The Forming Limit Diagram as the classic failure criterion in forming simulation is only partially suitable for this class of steels. An improvement of the failure prediction can be obtained by using damage mechanics. Therefore, an exact knowledge of the material-specific damage is essential for the application of various damage models. In this paper the results of microstructure analysis of a dual-phase steel and a complex-phase steel with a tensile strength of 1000 MPa are shown comparatively at various stress conditions. The objective is to characterize the basic damage mechanisms and based on this to assess the crack sensitivity of both steels. First a structural analysis with regard to non-metallic inclusions, the microstructural morphology, phase identification and the difference in microhardness between the structural phases is carried out. Subsequently, the development of the microstructure at different stress states between uniaxial and biaxial tension is examined. The damage behavior is characterized and quantified by the increase in void density, void size and the quantity of voids. The dominant damage mechanism of the dual-phase steel is the void initiation at phase boundaries, within harder structural phases and at inclusions. In contrast the complex-phase steel shows a significant growth of a smaller amount of voids which initiate only at inclusions. To quantify the damage tolerance and the susceptibility of cracking the criterion of the fracture forming limit line (FFL) is used. The respective statements are supported by results of investigations regarding the edge-crack sensitivity.

  9. Novel Hierarchical Fall Detection Algorithm Using a Multiphase Fall Model

    Science.gov (United States)

    Hsieh, Chia-Yeh; Liu, Kai-Chun; Huang, Chih-Ning; Chu, Woei-Chyn; Chan, Chia-Tai

    2017-01-01

    Falls are the primary cause of accidents for the elderly in the living environment. Reducing hazards in the living environment and performing exercises for training balance and muscles are the common strategies for fall prevention. However, falls cannot be avoided completely; fall detection provides an alarm that can decrease injuries or death caused by the lack of rescue. The automatic fall detection system has opportunities to provide real-time emergency alarms for improving the safety and quality of home healthcare services. Two common technical challenges are also tackled in order to provide a reliable fall detection algorithm, including variability and ambiguity. We propose a novel hierarchical fall detection algorithm involving threshold-based and knowledge-based approaches to detect a fall event. The threshold-based approach efficiently supports the detection and identification of fall events from continuous sensor data. A multiphase fall model is utilized, including free fall, impact, and rest phases for the knowledge-based approach, which identifies fall events and has the potential to deal with the aforementioned technical challenges of a fall detection system. Seven kinds of falls and seven types of daily activities arranged in an experiment are used to explore the performance of the proposed fall detection algorithm. The overall performances of the sensitivity, specificity, precision, and accuracy using a knowledge-based algorithm are 99.79%, 98.74%, 99.05% and 99.33%, respectively. The results show that the proposed novel hierarchical fall detection algorithm can cope with the variability and ambiguity of the technical challenges and fulfill the reliability, adaptability, and flexibility requirements of an automatic fall detection system with respect to the individual differences. PMID:28208694

  10. Practical strategies for enhancing adherence to treatment regimen in inflammatory bowel disease.

    Science.gov (United States)

    Greenley, Rachel N; Kunz, Jennifer H; Walter, Jennifer; Hommel, Kevin A

    2013-06-01

    Promoting adherence to treatment among pediatric and adult patients with inflammatory bowel disease (IBD) is a critical yet challenging task for health care providers. Several existing interventions to enhance adherence among individuals with IBD offer useful information about practical strategies to enhance adherence. The current review article has 3 goals. First, the review provides a context for understanding treatment regimen adherence in IBD by reviewing key definitional, measurement, and conceptual challenges in this area. Next, published studies focused on interventions to enhance adherence in IBD are briefly summarized, followed by a synthesis of practical adherence promotion strategies for use in IBD by health care providers. Strategies are distinguished by the level of evidence supporting their utility as well as by age group. Finally, recommendations for future research to facilitate the development and implementation of practical, evidence-based strategies for adherence promotion in IBD are provided. Findings from the literature review suggest that strategies including education, regimen simplification, and use of reminder systems and organizational strategies (e.g., pill boxes) are likely to be best suited for addressing accidental nonadherence. In contrast, addressing motivational issues, teaching problem-solving skills, and addressing problematic patterns of family functioning are more likely to benefit individuals displaying intentional nonadherence.

  11. Optimization of SCF feeding regimen for ex vivo expansion of cord blood hematopoietic stem cells.

    Science.gov (United States)

    Du, Zheng; Cai, Haibo; Ye, Zhaoyang; Tan, Wen-Song

    2012-12-15

    Stem cell factor (SCF) plays important roles in ex vivo expansion of hematopoietic stem cells (HSCs). In this study, the effects of dose and feeding time of SCF on ex vivo expansion of CD34(+) cells were investigated in serum-free medium supplemented with a cytokine cocktail composed of SCF, thrombopoietin (TPO) and flt3-ligand (FL). Among the four tested doses (0, 5, 50 and 500ng/mL), a SCF dose of 50ng/mL was demonstrated to be most favorable for ex vivo expansion of CD34(+) cells, which resulted in 34.22±10.80 and 8.89±1.25 folds of expansion regarding total cells and CD34(+) cells, respectively. Meanwhile, the specific growth rate of cells, the consumption rate of SCF and the percentage of CD34(+)c-kit(+) cells during the 21-day culture process were analyzed. The results indicated that initial 4-day period was a critical stage for SCF functioning on CD34(+) cells during ex vivo expansion. Based on this, a modified SCF feeding regimen was proposed, in which SCF (50ng/mL) was only supplemented on day 0 in the cytokine cocktail and cells were then fed with TPO and FL till the end of culture. It was found that this SCF feeding regimen could expand CD34(+) cells efficiently, thus providing a cost-effect expansion protocol for HSCs.

  12. In situ imaging of multiphase bio-interfaces at the micro-/nanoscale.

    Science.gov (United States)

    Chen, Peipei; Jiang, Lei; Han, Dong

    2011-10-17

    The multiphase bio-interfacial system constituted by biological surfaces and their surrounding environment is usually considered to be an essential clue for exploring the mysterious relationship between surface architecture and function. As a visualizing method to understand these systems, in situ imaging of multiphase interfaces (e.g., air/liquid/solid and oil/water/solid systems) at the micro-/nanoscale, still remains a huge challenge, as a result of their heterogeneity and complexity. Here, recent progress on real-space micro-/nanoscale imaging of multiphase bio-interfacial systems is reviewed; this includes several techniques and imaging results on bio-interfaces, such as the lotus leaf, fish scale, living cell's surface, and fresh tissue surface. The results evidently show that interfacial structures have a significant impact on the state of the microscopic multiphase interface, further influencing specific functions. Based on this research, technical innovations, some more complicated multiphase interface systems, and structure-function coupling mechanism are proposed.

  13. Prediction of Separation Length of Turbulent Multiphase Flow Using Radiotracer and Computational Fluid Dynamics Simulation

    Directory of Open Access Journals (Sweden)

    S. Sugiharto1

    2013-04-01

    Full Text Available Multiphase flow modeling presents great challenges due to its extreme importance in various industrial and environmental applications. In the present study, prediction of separation length of multiphase flow is examined experimentally by injection of two kinds of iodine-based radiotracer solutions into a hydrocarbon transport pipeline (HCT having an inner diameter of 24 in (60,96 m. The main components of fluids in the pipeline are water 95%, crude oil 3% and gas 2%. A radiotracing experiment was carried out at the segment of pipe which is located far from branch points with assumptions that stratified flows in such segment were achieved. Two radiation detectors located at 80 and 100 m from injection point were used to generate residence time distribution (RTD curve resulting from injection of radiotracer solutions. Multiphase computational fluid dynamics (CFD simulations using Eulerian-Eulerian control volume and commercial CFD package Fluent 6.2 were employed to simulate separation length of multiphase flow. The results of study shows that the flow velocity of water is higher than the flow rate of crude oil in water-dominated system despite the higher density of water than the density of the crude oil. The separation length in multiphase flow predicted by Fluent mixture model is approximately 20 m, measured from injection point. This result confirms that the placement of the first radiation detector at the distance 80 m from the injection point was correct

  14. Basis for selecting optimum antibiotic regimens for secondary peritonitis.

    Science.gov (United States)

    Maseda, Emilio; Gimenez, Maria-Jose; Gilsanz, Fernando; Aguilar, Lorenzo

    2016-01-01

    Adequate management of severely ill patients with secondary peritonitis requires supportive therapy of organ dysfunction, source control of infection and antimicrobial therapy. Since secondary peritonitis is polymicrobial, appropriate empiric therapy requires combination therapy in order to achieve the needed coverage for both common and more unusual organisms. This article reviews etiological agents, resistance mechanisms and their prevalence, how and when to cover them and guidelines for treatment in the literature. Local surveillances are the basis for the selection of compounds in antibiotic regimens, which should be further adapted to the increasing number of patients with risk factors for resistance (clinical setting, comorbidities, previous antibiotic treatments, previous colonization, severity…). Inadequate antimicrobial regimens are strongly associated with unfavorable outcomes. Awareness of resistance epidemiology and of clinical consequences of inadequate therapy against resistant bacteria is crucial for clinicians treating secondary peritonitis, with delicate balance between optimization of empirical therapy (improving outcomes) and antimicrobial overuse (increasing resistance emergence).

  15. Noncompliance with Medical Regimen in Haemodialysis Treatment: A Case Study

    Directory of Open Access Journals (Sweden)

    Paraskevi Theofilou

    2011-01-01

    Full Text Available Patients undergoing haemodialysis treatment have a high burden of disease (particularly cardiovascular comorbidities affecting their quality of life and dramatically shortening life expectancy. Effective chronic kidney disease (CKD control requires regular preventive medication and a response to that medication. Poor receptiveness to CKD medication can be related to individual variability in the dose needed to achieve a response, as well as to low-adherent behaviour in relation to the CKD medication regimen. Some patients, though not many, according to studies' findings, abuse the medical regimen as a result of suicidal tendencies. The present case gave us the opportunity to consider the causes and clinical findings and review the specific psychological interventions for patients with CKD.

  16. Predictive tools for designing new insulins and treatment regimens

    DEFF Research Database (Denmark)

    Klim, Søren

    The thesis deals with the development of "Predictive tools for designing new insulins and treatments regimens" and consists of two parts: A model based approach for bridging properties of new insulin analogues from glucose clamp experiments to meal tolerance tests (MTT) and a second part that des......The thesis deals with the development of "Predictive tools for designing new insulins and treatments regimens" and consists of two parts: A model based approach for bridging properties of new insulin analogues from glucose clamp experiments to meal tolerance tests (MTT) and a second part...... on ordinary differential equations. The absence of such a program motivated the development of new a tool with PK/PD features, SDEs and mixed effects. Part II presents a software package which was developed in order to be able to handle SDEs with mixed effects. The package was implemented in R which allowed...

  17. Efficacy of a Morinda citrifolia Based Skin Care Regimen

    Directory of Open Access Journals (Sweden)

    Brett J. West

    2012-04-01

    Full Text Available A six week clinical trial of a Morinda citrifolia (noni based skin care regimen was conducted with 49 women, ages 38 to 55 years. Daily application of three product formulations to the face and neck resulted in significant reductions in lateral canthal fine lines and wrinkles (crow’s feet, as measured by technician scoring and digital image analysis. Use of the regimen also improved skin elasticity and firmness Cutometer® measurements. No evidence of skin irritation was present in any participant at any time during the trial. A study questionnaire revealed that the measured improvements were visibly perceptible to more than 90% of the participants. The trial results substantiate traditional uses of the noni plant to improve skin health.

  18. Equivalent normalized total dose estimates in cyberknife radiotherapy dose delivery in prostate cancer hypofractionation regimens.

    Science.gov (United States)

    Sudahar, H; Kurup, P G G; Murali, V; Mahadev, P; Velmurugan, J

    2012-04-01

    As the α/β value of prostate is very small and lower than the surrounding critical organs, hypofractionated radiotherapy became a vital mode of treatment of prostate cancer. Cyberknife (Accuray Inc., Sunnyvale, CA, USA) treatment for localized prostate cancer is performed in hypofractionated dose regimen alone. Effective dose escalation in the hypofractionated regimen can be estimated if the corresponding conventional 2 Gy per fraction equivalent normalized total dose (NTD) distribution is known. The present study aims to analyze the hypofractionated dose distribution of localized prostate cancer in terms of equivalent NTD. Randomly selected 12 localized prostate cases treated in cyberknife with a dose regimen of 36.25 Gy in 5 fractions were considered. The 2 Gy per fraction equivalent NTDs were calculated using the formula derived from the linear quadratic (LQ) model. Dose distributions were analyzed with the corresponding NTDs. The conformity index for the prescribed target dose of 36.25 Gy equivalent to the NTD dose of 90.63 Gy (α/β = 1.5) or 74.31 Gy (α/β = 3) was ranging between 1.15 and 1.73 with a mean value of 1.32 ± 0.15. The D5% of the target was 111.41 ± 8.66 Gy for α/β = 1.5 and 90.15 ± 6.57 Gy for α/β = 3. Similarly, the D95% was 91.98 ± 3.77 Gy for α/β = 1.5 and 75.35 ± 2.88 Gy for α/β = 3. The mean values of bladder and rectal volume receiving the prescribed dose of 36.25 Gy were 0.83 cm3 and 0.086 cm3, respectively. NTD dose analysis shows an escalated dose distribution within the target for low α/β (1.5 Gy) with reasonable sparing of organs at risk. However, the higher α/β of prostate (3 Gy) is not encouraging the fact of dose escalation in cyberknife hypofractionated dose regimen of localized prostate cancer.

  19. Antiepileptic drug regimens and major congenital abnormalities in the offspring.

    Science.gov (United States)

    Samrén, E B; van Duijn, C M; Christiaens, G C; Hofman, A; Lindhout, D

    1999-11-01

    To assess the risk of major congenital abnormalities associated with specific antiepileptic drug regimens, a large retrospective cohort study was performed. The study comprised 1,411 children born between 1972 and 1992 in four provinces in The Netherlands who were born to mothers with epilepsy and using antiepileptic drugs during the first trimester of pregnancy, and 2,000 nonepileptic matched controls. We found significantly increased risks of major congenital abnormalities for carbamazepine and valproate monotherapy, with evidence for a significant dose-response relationship for valproate. The risk of major congenital abnormalities was nonsignificantly increased for phenobarbital monotherapy when caffeine comedication was excluded, but a significant increase in risk was found when caffeine was included. Phenytoin monotherapy was not associated with an increased risk of major congenital abnormalities. Regarding polytherapy regimens, increased risks were found for several antiepileptic drug combinations. Clonazepam, in combination with other antiepileptic drugs, showed a significantly increased relative risk. Furthermore, there were significantly increased relative risks for the combination of carbamazepine and valproate and the combination of phenobarbital and caffeine with other antiepileptic drugs. This study shows that most antiepileptic drug regimens were associated with an increased risk of major congenital abnormalities in the offspring, in particular valproate (dose-response relationship) and carbamazepine monotherapy, benzodiazepines in polytherapy, and caffeine comedication in combinations with phenobarbital.

  20. Care of Patients With HIV Infection: Antiretroviral Drug Regimens.

    Science.gov (United States)

    Bolduc, Philip; Roder, Navid; Colgate, Emily; Cheeseman, Sarah H

    2016-04-01

    The advent of combination antiretroviral drug regimens has transformed HIV infection from a fatal illness into a manageable chronic condition. All patients with HIV infection should be considered for antiretroviral therapy, regardless of CD4 count or HIV viral load, for individual benefit and to prevent HIV transmission. Antiretroviral drugs affect HIV in several ways: entry inhibitors block HIV entry into CD4 T cells; nucleotide and nucleoside reverse transcriptase inhibitors prevent reverse transcription from RNA to DNA via chain-terminating proteins; nonnucleoside reverse transcriptase inhibitors prevent reverse transcription through enzymatic inhibition; integrase strand transfer inhibitors block integration of viral DNA into cellular DNA; protease inhibitors block maturation and production of the virus. Current guidelines recommend six combination regimens for initial therapy. Five are based on tenofovir and emtricitabine; the other uses abacavir and lamivudine. Five include integrase strand transfer inhibitors. HIV specialists should assist with treating patients with complicated HIV infection, including patients with treatment-resistant HIV infection, coinfection with hepatitis B or C virus, pregnancy, childhood infections, severe opportunistic infections, complex drug interactions, significant drug toxicity, or comorbidities. Family physicians can treat most patients with HIV infection effectively by choosing appropriate treatment regimens, monitoring patients closely, and retaining patients in care.

  1. Modelling and simulation of multi-phase effects on X-ray elasticity constants

    Energy Technology Data Exchange (ETDEWEB)

    Freour, S.; Gloaguen, D.; Guillen, R. [Laboratoire d' Applications des Materiaux a la Mecanique (L.A.M.M.), L.A.M.M.-C.R.T.T., Boulevard de L' Universite, BP 406, 44602 Saint Nazaire Cedex (France); Francois, M. [Laboratoire des Systemes Mecaniques et d' Ingenierie Simultanee (L.A.S.M.I.S.), Universite de Technologie de Troyes, 12 Rue Marie Curie, BP 2060, 10010 Troyes (France)

    2003-10-01

    This paper deals with the calculation of X-ray Elasticity Constants (XEC) of phases embedded in multi-phase polycrystals. A three scales (macroscopic, pseudo-macroscopic, mesoscopic) model based on the classical self-consistent formalism is developed in order to analyse multi-phase effects on XEC values. Simulations are performed for cubic or hexagonal crystallographic structure phases embedded in several two-phases materials. In fact, it is demonstrated that XEC vary with the macroscopic stiffness of the whole polycrystal. In consequence, the constants of one particular phase depend on the elastic behaviour and the volume fraction of all the phases constituting the material. Now, XEC play a leading role in pseudo-macroscopic stresses determination by X-Ray Diffraction (XRD) methods. In this work, a quantitative analysis of the multi-phase effects on stresses determination by XRD methods was performed. Numerical results will be compared and discussed. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  2. Multiphase surfactant-assisted reaction-separation system in a microchannel reactor

    Institute of Scientific and Technical Information of China (English)

    Salah ALJBOUR; Tomohiko TAGAWA; Mohammad MATOUQ; Hiroshi YAMADA

    2009-01-01

    The Lewis acid-catalyzed addition of tri-methylsilyl cyanide to p-chlorobenzaldehyde in a micro-channel reactor was investigated. The microchannel was integrated to promote both reaction and separation of the biphase system. FeF3 and Cu(triflate)2 were used as water-stable Lewis acid catalysts. Sodium dodecyl sulfate was incorporated in the organic-aqueous system to enhance the reactivity and to manipulate the multiphase flow inside the microchannel. It was found that the dynamics and the kinetics of the multiphase reaction were affected by the new micellar system. Parallel multiphase flow inside the microchannel was obtained, allowing for continuous and acceptable phase separation. Enhanced selectivity was achieved by operating at lower conversion values.

  3. Multiphase Flow Dynamics 4 Turbulence, Gas Adsorption and Release, Diesel Fuel Properties

    CERN Document Server

    Kolev, Nikolay Ivanov

    2012-01-01

    The present Volume 4 of the successful monograh package “Multiphase Flow Dynamics”is devoted to selected Chapters of the multiphase fluid dynamics that are important for practical applications but did not find place in the previous volumes. The state of the art of the turbulence modeling in multiphase flows is presented. As introduction, some basics of the single phase boundary layer theory including some important scales and flow oscillation characteristics in pipes and rod bundles are presented. Then the scales characterizing the dispersed flow systems are presented. The description of the turbulence is provided at different level of complexity: simple algebraic models for eddy viscosity, simple algebraic models based on the Boussinesq hypothesis, modification of the boundary layer share due to modification of the bulk turbulence, modification of the boundary layer share due to nucleate boiling. The role of the following forces on the mathematical description of turbulent flows is discussed: the lift fo...

  4. A QCQP Approach for OPF in Multiphase Radial Networks with Wye and Delta Connections: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Zamzam, Ahmed, S.; Zhaoy, Changhong; Dall' Anesey, Emiliano; Sidiropoulos, Nicholas D.

    2017-06-27

    This paper examines the AC Optimal Power Flow (OPF) problem for multiphase distribution networks featuring renewable energy resources (RESs). We start by outlining a power flow model for radial multiphase systems that accommodates wye-connected and delta-connected RESs and non-controllable energy assets. We then formalize an AC OPF problem that accounts for both types of connections. Similar to various AC OPF renditions, the resultant problem is a non convex quadratically-constrained quadratic program. However, the so-called Feasible Point Pursuit-Successive Convex Approximation algorithm is leveraged to obtain a feasible and yet locally-optimal solution. The merits of the proposed solution approach are demonstrated using two unbalanced multiphase distribution feeders with both wye and delta connections.

  5. Performance analysis of variable speed multiphase induction motor with pole phase modulation

    Directory of Open Access Journals (Sweden)

    Liu Huijuan

    2016-09-01

    Full Text Available The pole phase modulation (PPM technique is an effective method to extend speed range and torque capabilities for an integrated starter and hybrid electric vehicles applications. In this paper, the five pole-phase combination types of a multiphase induction motor (IM with 36 stator slots and 36 stator conductors are presented and compared quantitatively by using the time-stepping finite element method (TS-FEM. The 36 stator conductors of the proposed multiphase IM are fed by a 36 leg inverter and the current phase angle and amplitude of each stator conductor can be controlled independently. This paper focuses on the winding connection, the PPM technique and the performance comparative analysis of each pole-phase combination types of the proposed multiphase IM. The flux distribution, air-gap flux density, output torque, core losses and efficiency of five pole-phase combination types have been investigated.

  6. Pore-scale simulation of multicomponent multiphase reactive transport with dissolution and precipitation

    CERN Document Server

    Chen, Li; Tang, Qing; Robinson, Bruce A; He, Ya-Ling; Tao, Wen-Quan

    2014-01-01

    Multicomponent multiphase reactive transport processes with dissolution-precipitation are widely encountered in energy and environment systems. A pore-scale two-phase multi-mixture model based on the lattice Boltzmann method (LBM) is developed for such complex transport processes, where each phase is considered as a mixture of miscible components in it. The liquid-gas fluid flow with large density ratio is simulated using the multicomponent multiphase pseudo-potential LB model; the transport of certain solute in the corresponding solvent is solved using the mass transport LB model; and the dynamic evolutions of the liquid-solid interface due to dissolution-precipitation are captured by an interface tracking scheme. The model developed can predict coupled multiple physicochemical processes including multiphase flow, multicomponent mass transport, homogeneous reactions in the bulk fluid and heterogeneous dissolution-precipitation reactions at the fluid-solid interface, and dynamic evolution of the solid matrix ...

  7. Treatment of multidrug-resistant pseudomonas aeruginosa using extended-infusion antimicrobial regimens.

    Science.gov (United States)

    Heil, Emily L; Lowery, Ashleigh V; Thom, Kerri A; Nicolau, David P

    2015-01-01

    In the management of multidrug-resistant infections in critically ill patients with multiorgan dysfunction, consideration must be given to the pharmacokinetics and pharmacodynamics of an antimicrobial agent to optimize dosing. We describe a 25-year-old woman who was undergoing thrice-weekly hemodialysis and developed multidrug-resistant Pseudomonas aeruginosa bacteremia secondary to infected left and right ventricular assist devices. After multiple courses of antibiotics, her blood cultures revealed that the infecting organism was becoming progressively more resistant to antibiotic options. Cefepime 2 g administered over 3 hours/day (in combination with colistimethate) provided adequate drug levels for multidrug-resistant, cefepime-intermediate P. aeruginosa bacteremia in this patient. We present the clinical case of this patient, followed by a discussion of possible therapeutic approaches to be considered, including illustration of the principles of using extended-infusion antimicrobial regimens, and present the patient's resulting clinical course.

  8. Drug regimens identified and optimized by output-driven platform markedly reduce tuberculosis treatment time

    Science.gov (United States)

    Lee, Bai-Yu; Clemens, Daniel L.; Silva, Aleidy; Dillon, Barbara Jane; Masleša-Galić, Saša; Nava, Susana; Ding, Xianting; Ho, Chih-Ming; Horwitz, Marcus A.

    2017-01-01

    The current drug regimens for treating tuberculosis are lengthy and onerous, and hence complicated by poor adherence leading to drug resistance and disease relapse. Previously, using an output-driven optimization platform and an in vitro macrophage model of Mycobacterium tuberculosis infection, we identified several experimental drug regimens among billions of possible drug-dose combinations that outperform the current standard regimen. Here we use this platform to optimize the in vivo drug doses of two of these regimens in a mouse model of pulmonary tuberculosis. The experimental regimens kill M. tuberculosis much more rapidly than the standard regimen and reduce treatment time to relapse-free cure by 75%. Thus, these regimens have the potential to provide a markedly shorter course of treatment for tuberculosis in humans. As these regimens omit isoniazid, rifampicin, fluoroquinolones and injectable aminoglycosides, they would be suitable for treating many cases of multidrug and extensively drug-resistant tuberculosis. PMID:28117835

  9. Insulin therapy for diabetes mellitus: treatment regimens and associated costs.

    Science.gov (United States)

    Charbonnel, B; Penfornis, A; Varroud-Vial, M; Kusnik-Joinville, O; Detournay, B

    2012-04-01

    To describe insulin therapy in patients with diabetes, to determine treatment costs and to compare costs among treatment regimens. This observational study was performed by 734 French pharmacists. Adult patients filling an insulin prescription were invited to participate. Participants provided information on their diabetes history and management. Levels of intensification of insulin therapy were determined by the number of injections in type 1 diabetes mellitus (T1DM) patients, and by the different schemes used in type 2 (T2DM) patients, such as basal/intermediate-acting insulin only, and regimens using both basal and rapid-acting insulin. Costs were evaluated according to official medication costs, nurse visits and glucose monitoring kits. A total of 361 patients with T1DM and 1902 with T2DM were enrolled in the survey. Patients with T1DM more frequently took 1-2 injections per day (46.3% of patients) and used single-dose basal insulin together with ≥1 dose of rapid insulin (43.8%). Patients with T2DM used multiple treatment regimens, with 58 different combinations documented. Most took basal/intermediate insulin only (42.5%) or combinations of basal/intermediate and rapid insulins (52.7%). Mean cost of insulin therapy was €27.4/week for T1DM and €45.4/week for T2DM. In T1DM, insulin was the biggest cost component and increased with the number of injections/day. In T2DM, nurse visits were the most important cost contributors irrespective of treatment regimen. Overall, the cost of insulin therapy increased with the complexity of the insulin schemes. Considerable heterogeneity is found in insulin treatment regimens used in everyday diabetes care. Payers should consider the full costs associated with the use of insulin rather than the cost of insulin alone. Treatment algorithms to harmonize insulin therapy should help to improve care, while encouraging patients to self-inject insulin should help to reduce costs. Copyright © 2011 Elsevier Masson SAS. All rights

  10. Three Postpartum Antiretroviral Regimens to Prevent Intrapartum HIV Infection

    Science.gov (United States)

    Nielsen-Saines, Karin; Watts, D. Heather; Veloso, Valdilea G.; Bryson, Yvonne J.; Joao, Esau C.; Pilotto, Jose Henrique; Gray, Glenda; Theron, Gerhard; Santos, Breno; Fonseca, Rosana; Kreitchmann, Regis; Pinto, Jorge; Mussi-Pinhata, Marisa M.; Ceriotto, Mariana; Machado, Daisy; Bethel, James; Morgado, Marisa G.; Dickover, Ruth; Camarca, Margaret; Mirochnick, Mark; Siberry, George; Grinsztejn, Beatriz; Moreira, Ronaldo I.; Bastos, Francisco I.; Xu, Jiahong; Moye, Jack; Mofenson, Lynne M.

    2013-01-01

    Background The safety and efficacy of adding antiretroviral drugs to standard zidovudine prophylaxis in infants of mothers with human immunodeficiency virus (HIV) infection who did not receive antenatal antiretroviral therapy (ART) because of late identification are unclear. We evaluated three ART regimens in such infants. Methods Within 48 hours after their birth, we randomly assigned formula-fed infants born to women with a peripartum diagnosis of HIV type 1 (HIV-1) infection to one of three regimens: zidovudine for 6 weeks (zidovudine-alone group), zidovudine for 6 weeks plus three doses of nevirapine during the first 8 days of life (two-drug group), or zidovudine for 6 weeks plus nelfinavir and lamivudine for 2 weeks (three-drug group). The primary outcome was HIV-1 infection at 3 months in infants uninfected at birth. Results A total of 1684 infants were enrolled in the Americas and South Africa (566 in the zidovudine-alone group, 562 in the two-drug group, and 556 in the three-drug group). The overall rate of in utero transmission of HIV-1 on the basis of Kaplan–Meier estimates was 5.7% (93 infants), with no significant differences among the groups. Intra-partum transmission occurred in 24 infants in the zidovudine-alone group (4.8%; 95% confidence interval [CI], 3.2 to 7.1), as compared with 11 infants in the two-drug group (2.2%; 95% CI, 1.2 to 3.9; P = 0.046) and 12 in the three-drug group (2.4%; 95% CI, 1.4 to 4.3; P = 0.046). The overall transmission rate was 8.5% (140 infants), with an increased rate in the zidovudine-alone group (P = 0.03 for the comparisons with the two- and three-drug groups). On multivariate analysis, zidovudine monotherapy, a higher maternal viral load, and maternal use of illegal substances were significantly associated with transmission. The rate of neutropenia was significantly increased in the three-drug group (P<0.001 for both comparisons with the other groups). Conclusions In neonates whose mothers did not receive ART

  11. Pattern recognition techniques for horizontal and vertically upward multiphase flow measurement

    Science.gov (United States)

    Arubi, Tesi I. M.; Yeung, Hoi

    2012-03-01

    The oil and gas industry need for high performing and low cost multiphase meters is ever more justified given the rapid depletion of conventional oil reserves that has led oil companies to develop smaller and marginal fields and reservoirs in remote locations and deep offshore, thereby placing great demands for compact and more cost effective solutions of on-line continuous multiphase flow measurement for well testing, production monitoring, production optimisation, process control and automation. The pattern recognition approach for clamp-on multiphase measurement employed in this study provides one means for meeting this need. High speed caesium-137 radioisotope-based densitometers were installed vertically at the top of a 50.8mm and 101.6mm riser as well as horizontally at the riser base in the Cranfield University multiphase flow test facility. A comprehensive experimental campaign comprising flow conditions typical of operating conditions found in the Petroleum Industry was conducted. The application of a single gamma densitometer unit, in conjunction with pattern recognition techniques to determine both the phase volume fractions and velocities to yield the individual phase flow rates of horizontal and vertically upward multiphase flows was investigated. The pattern recognition systems were trained to map the temporal fluctuations in the multiphase mixture density with the individual phase flow rates using statistical features extracted from the gamma counts signals as their inputs. Initial results yielded individual phase flow rate predictions to within ±5% relative error for the two phase airwater flows and ±10% for three phase air-oil-water flows data.

  12. Multiphase fluid-rock reactions among supercritical carbon dioxide, brine, aquifer, and caprock: relevance to geologic sequestration of carbon

    Energy Technology Data Exchange (ETDEWEB)

    Kaszuba, J. P. (John P.); Janecky, D. R. (David R.); Snow, M. G. (Marjorie G.)

    2004-01-01

    The reactive behavior of a multiphase fluid (supercritical CO{sub 2} and brine) under physical-chemical conditions relevant to geologic storage and sequestration in a carbon repository is largely unknown. Experiments were conducted in a flexible cell hydrothermal apparatus to evaluate multiphase fluid-rock (aquifer plus caprock) reactions that may impact repository integrity.

  13. Reductions in blood lead overestimate reductions in brain lead following repeated succimer regimens in a rodent model of childhood lead exposure.

    Science.gov (United States)

    Stangle, Diane E; Strawderman, Myla S; Smith, Donald; Kuypers, Mareike; Strupp, Barbara J

    2004-03-01

    Although many studies have demonstrated the efficacy of succimer chelation in reducing blood and brain lead levels, the relative efficacy of the drug in the two tissues is less well understood. This issue is important because blood lead levels after chelation are used clinically to estimate reductions in the brain, the most critical organ in considering lead-induced neurotoxicity. The present study was designed to further investigate this issue, using multiple chelation regimens. Long-Evans rats were exposed to one of three lead exposure regimens from birth until postnatal day 40, followed by treatment with succimer (one or two 3-week regimens) or vehicle. The results indicated that one succimer regimen was significantly superior to vehicle treatment in lowering lead levels in both blood and brain across the entire 8-week follow-up period. Similarly, a second succimer regimen offered significant additional benefit relative to one regimen for both blood and brain across the 4-week follow-up period. However, several findings revealed that succimer-induced reductions in brain lead lagged behind reductions in blood lead and were generally smaller in magnitude. Furthermore, a rebound was detected in blood, but not brain, lead levels after both succimer regimens. Given the results of this study, we urge caution in using blood lead as a surrogate for brain lead levels, particularly during and immediately after chelation treatment when reductions in blood lead levels overestimate reductions in brain lead levels. The present results suggest that, in clinical use, succimer treatment may need to extend beyond the point at which blood lead levels have dropped to an "acceptable" target value in order to effectively reduce brain lead levels and minimize neurotoxicity.

  14. Toxicities of different first-line chemotherapy regimens in the treatment of advanced ovarian cancer

    Science.gov (United States)

    Qu, Chang-Ping; Sun, Gui-Xia; Yang, Shao-Qin; Tian, Jun; Si, Jin-Ge; Wang, Yi-Feng

    2017-01-01

    Abstract Background: Ovarian cancer (OC) is the 5th leading cause of cancer-related deaths around the world, and several chemotherapy regimens have been applied in the treatment of OC. We aim to compare toxicities of different chemotherapy regimens in the treatment of advanced ovarian cancer (AOC) using network meta-analysis. Methods: Literature research in Cochrane Library, PubMed, and EMBASE was performed up to November 2015. Eligible randomized controlled trials (RCTs) of different chemotherapy regimens were included. Network meta-analysis combined direct and indirect evidence to assess pooled odds ratios (ORs) and draw the surface under the cumulative ranking (SUCRA) curves. Results: Thirteen eligible RCTs were included in this network meta-analysis, including 8 chemotherapy regimens (paclitaxel + carboplatin [PC], pegylated liposomal doxorubicin [PLD] + carboplatin, carboplatin, gemcitabine + carboplatin, paclitaxel, PC + epirubicin, PC + topotecan, docetaxel + carboplatin). Gemcitabine + carboplatin regimen exerted higher incidence of anemia when compared with carboplatin and paclitaxel regimens. The incidence of febrile neutropenia of gemcitabine + carboplatin regimen was higher than that of PC, PLD + carboplatin, carboplatin, and PC + topotecan regimens. Topotecan PC + epirubicin regimen had a higher toxicity, comparing with PC, PLD + carboplatin, and PC + topotecan regimens. As for thrombocytopenia, gemcitabine + carboplatin chemotherapy regimen produced an obviously higher toxicity than PC and carboplatin. As for nausea, PLD + carboplatin chemotherapy regimen had a significantly higher toxicity than that of carboplatin chemotherapy regimen. Moreover, when compared with PC and carboplatin chemotherapy regimens, the toxicity of PC + epirubicin was greatly higher to patients with AOC. Conclusion: The nonhematologic toxicity of PLD + carboplatin regimen was higher than other regimens, which

  15. The Relationship between Cognitive Appraisal and Adherence to Medical Regimens in Type 2 Diabetic Patients

    OpenAIRE

    Shahnaz Ahrari; Ali Mohammadpour; Zahra Amouzeshi; Alireza Agha-Yousefi

    2014-01-01

    Introduction: Non-adherence to medical regimen has remained a challenge to the medical profession as well as to social sciences. To achieve positive results, the factors negatively impacting patient adherence to medical regimens (i.e., diet, drug and exercise regimen) must be scrutinized in detail. The objective of this research was to explore the relationship between cognitive appraisal and adherence to medical regimens in type 2 diabetic patients. Methods: In this correla...

  16. Micro-Ct Imaging of Multi-Phase Flow in Carbonates and Sandstones

    Science.gov (United States)

    Andrew, M. G.; Bijeljic, B.; Blunt, M. J.

    2013-12-01

    One of the most important mechanisms that limits the escape of CO2 when injected into the subsurface for the purposes of carbon storage is capillary trapping, where CO2 is stranded as pore-scale droplets (ganglia). Prospective storage sites are aquifers or reservoirs that tend to be at conditions where CO2 will reside as a super-critical phase. In order to fully describe physical mechanisms characterising multi-phase flow during and post CO2 injection, experiments need to be conducted at these elevated aquifer/reservoir conditions - this poses a considerable experimental challenge. A novel experimental apparatus has been developed which uses μCT scanning for the non-invasive imaging of the distribution of CO2 in the pore space of rock with resolutions of 7μm at temperatures and pressures representative of the conditions present in prospective saline aquifer CO2 storage sites. The fluids are kept in chemical equilibrium with one-another and with the rock into which they are injected. This is done to prevent the dissolution of the CO2 in the brine to form carbonic acid, which can then react with the rock, particularly carbonates. By eliminating reaction we study the fundamental mechanisms of capillary trapping for an unchanging pore structure. In this study we present a suite of results from three carbonate and two sandstone rock types, showing that, for both cases the CO2 acts as the non-wetting phase and significant quantities of CO2 is trapped. The carbonate examined represent a wide variety of pore topologies with one rock with a very well connected, high porosity pore space (Mt Gambier), one with a lower porosity, poorly connected pore space (Estaillades) and one with a cemented bead pack type pore space (Ketton). Both sandstones (Doddington and Bentheimer) were high permeability granular quartzites. CO2 was injected into each rock, followed by brine injection. After brine injection the entire length of the rock core was scanned, processed and segmented into

  17. Multiphase control volume finite element simulations of fractured reservoirs

    Science.gov (United States)

    Fu, Yao

    With rapid evolution of hardware and software techniques in energy sector, reservoir simulation has become a powerful tool for field development planning and reservoir management. Many of the widely used commercial simulators were originally designed for structured grids and implemented with finite difference method (FDM). In recent years, technical advances in griding, fluid modeling, linear solver, reservoir and geological modeling, etc. have created new opportunities. At the same time, new reservoir simulation technology is required for solving large-scale heterogeneous problems. A three-dimensional, three-phase black-oil reservoir simulator has been developed using the control volume finite element (CVFE) formulation. Flux-based upstream weighting is employed to ensure flux continuity. The CVFE method is embedded in a fully-implicit formulation. State-of-the-art parallel, linear solvers are used. The implementation takes the advantages of object-oriented programming capabilities of C++ to provide maximum reuse and extensibility for future students. The results from the simulator have excellent agreement with those from commercial simulators. The convergence properties of the new simulator are verified using the method of manufactured solutions. The pressure and saturation solutions are verified to be first-order convergent as expected. The efficiency of the simulators and their capability to handle real large-scale field models are improved by implementing the models in parallel. Another aspect of the work dealt with multiphase flow of fractured reservoirs was performed. The discrete-fracture model is implemented in the simulator. Fractures and faults are represented by lines and planes in two- and three-dimensional spaces, respectively. The difficult task of generating an unstructured mesh for complex domains with fractures and faults is accomplished in this study. Applications of this model for two-phase and three-phase simulations in a variety of fractured

  18. THREE DIMENSIONAL MULTIPHASE COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF VENTILATED SUPERCAVITATION

    Institute of Scientific and Technical Information of China (English)

    YANG Wugang; ZHANG Yuwen; YANG Jie; ZUO Liankai

    2008-01-01

    For some vehicles travelling through water, it is advantageous to cover the vehicle in a supercavity for the sake of reducing the drag acting on it. The method of artificial ventilation is most effective for generating and dominating the supercavity. This paper focuses on the numerical simulation of flow field around three dimensional body. The method is based on the multiphase computational fluid dynamics (CFD) model combined with the turbulence model and the full cavity model. The flow field of cavity is simulated by solving the compressible Navier-Stokes equations. The fundamental similarity parameters of ventilated supercavitaty flows that include cavitation number, Froude number, ventilation rate and drag coefficient are all investigated numerically in the case of steady flow and gravity field. We discuss the following simulations results in section 3: The variations of the cavitation number and the supercavity's relative diameter with ventilation rate (subtopic 3.1); The drag coefficient versus the cavitation number (subtopic 3.2); Deformation of supercavity axis caused by gravitational effect for three different fixed Froude numbers-2.8, 3.4, 4.2 (subtopic 3.3). In subtopic 3.2, we give the comparison results of the drag reduction ratio among numerical simulation and experiment conducted in hydrodynamic tunnel and towing tank respectively. In subtopic 3.3, we summarize our discussion of gravitational effect on the axis deformation of supercavity as follows: In the case of smaller Froude number, the inclination of the cavity axis increases monotonously with increasing horizontal length, and reaches its maximal value at the end of supercavity; This deformation can be almost completely negligible when the Froude number Fr>7. The comparisons with the experimental data in the hydrodynamic tunnel and the towing tank indicate that the present method is effective for predicting the flows around ventilated supercavity; that the numerical results is in good agreement

  19. The distribution of mean and fluctuating magnetic fields in the multi-phase ISM

    CERN Document Server

    Evirgen, Cetin Can; Shukurov, Anvar; Fletcher, Andrew; Bushby, Paul

    2016-01-01

    We explore the effects of the multi-phase structure of the interstellar medium (ISM) on galactic magnetic fields. Basing our analysis on compressible magnetohydrodynamic (MHD) simulations of supernova-driven turbulence in the ISM, we investigate the properties of both the mean and fluctuating components of the magnetic field. We find that the mean magnetic field preferentially resides in the warm phase and is generally absent from the hot phase. The fluctuating magnetic field does not show such pronounced sensitivity to the multi-phase structure.

  20. Modeling and Computing Example for Effective Electromagnetic Parameters of Multiphase Composite Media

    Institute of Scientific and Technical Information of China (English)

    SONG Wei-Li; YUAN Jie; HOU Zhi-Ling; CAO Mao-Sheng

    2009-01-01

    A method using strong fluctuation theory (SFT) to compute the effective electromagnetic parameters of multiphase composite media, and common materials used to design radar-absorbing materials, is demonstrated. The effective electromagnetic parameters of ultrafine caxbonyl-iron (DT-50) and fiber fabric, which are both multiphase composite media and represent coated and structured radar absorbing materials, respectively, are investigated, and the corresponding equations of electromagnetic parameters by using the SFT axe attained. Moreover, we design a program to simplify the solutions, and the results are discussed.

  1. New Multiphase Hybrid Boost Converter with Wide Conversion Ratio for PV System

    Directory of Open Access Journals (Sweden)

    Ioana-Monica Pop-Calimanu

    2014-01-01

    Full Text Available A new multiphase hybrid boost converter, with wide conversion ratio as a solution for photovoltaic energy system, is presented in this paper. To ensure that all the phases of the converter operate at the same switching frequency we use interleaving topology. The proposed converter can be used as an interface between the PV system and the DC load/inverter. This multiphase converter has the advantage of reduced value and physical size of the input and output capacitor as well as the effort for the inductors. To validate the operation of the converter we provide the analyses and the simulation results of the converter.

  2. Time-resolved quantitative multiphase interferometric imaging of a highly focused ultrasound pulse

    CERN Document Server

    Souris, Fabien; Jacquier, Philippe; Dupont-Roc, Jacques; Arvengas, Arnaud; Caupin, Frédéric; 10.1364/AO.49.006127

    2010-01-01

    Interferometric imaging is a well established method to image phase objects by mixing the image wavefront with a reference one on a CCD camera. It has also been applied to fast transient phenomena, mostly through the analysis of single interferograms. It is shown that for repetitive phenomena multiphase acquisition brings significant advantages. A 1 MHz focused sound field emitted by a hemispherical piezotransducer in water is imaged as an example. Quantitative image analysis provides high resolution sound field profiles. Pressure at focus determined by this method agrees with measurements from a fiber-optic probe hydrophone. This confirms that multiphase interferometric imaging can indeed provide quantitative measurements.

  3. The TOUGH codes - a family of simulation tools for multiphase flowand transport processes in permeable media

    Energy Technology Data Exchange (ETDEWEB)

    Pruess, Karsten

    2003-08-08

    Numerical simulation has become a widely practiced andaccepted technique for studying flow and transport processes in thevadose zone and other subsurface flow systems. This article discusses asuite of codes, developed primarily at Lawrence Berkeley NationalLaboratory (LBNL), with the capability to model multiphase flows withphase change. We summarize history and goals in the development of theTOUGH codes, and present the governing equations for multiphase,multicomponent flow. Special emphasis is given to space discretization bymeans of integral finite differences (IFD). Issues of code implementationand architecture are addressed, as well as code applications,maintenance, and future developments.

  4. Whitham's Method and Dubrovin-Novikov Bracket in Single-Phase and Multiphase Cases

    Directory of Open Access Journals (Sweden)

    Andrei Ya. Maltsev

    2012-12-01

    Full Text Available In this paper we examine in detail the procedure of averaging of the local field-theoretic Poisson brackets proposed by B.A. Dubrovin and S.P. Novikov for the method of Whitham. The main attention is paid to the questions of justification and the conditions of applicability of the Dubrovin-Novikov procedure. Separate consideration is given to special features of single-phase and multiphase cases. In particular, one of the main results is the insensitivity of the procedure of bracket averaging to the appearance of ''resonances'' which can arise in the multi-phase situation.

  5. Influence of Hot Deformation and Subsequent Austempering on the Mechanical Properties of Hot Rolled Multiphase Steel

    Institute of Scientific and Technical Information of China (English)

    Zhuang LI; Di WU

    2006-01-01

    Influence of hot deformation and subsequent austempering on the mechanical properties of hot rolled multiphase steel was investigated. Thermo-mechanical control processing (TMCP) was conducted by using a laboratory hot rolling mill, where three different kinds of finishing rolling reduction, and austemperings with various isothermal holding duration were applied. The results have shown that a multiphase microstructure consisting of polygonal ferrite, granular bainite and larger amount of stabilized retained austenite can be obtained by controlled rolling processes. Mechanical properties increase with increasing the amount of deformation because of the stabilization of retained austenite. Ultimate tensile strength (σb), total elongation (δ)36% and 28476 MPa%, respectively) at optimal processes.

  6. Comparison of two once-daily regimens with a regimen consisting of nelfinavir, didanosine, and stavudine in antiretroviral therapy-naive adults : 48-week results from the antiretroviral regimen evaluation study (ARES)

    NARCIS (Netherlands)

    Lowe, SH; Wensing, AMJ; Hassink, EAM; ten Kate, RW; Richter, C; Schreij, G; Koopmans, PP; Juttmann, J.; van der Tweel, I.; Lange, JMA; Borleffs, JCC

    2005-01-01

    Background: To improve the dosing frequency and pill burden of antiretroviral therapy, we compared two once-daily dosed regimens to a twice-daily dosed regimen. Method: HIV-1-infected, antiretroviral drug-naive adults were randomized to either twice-daily nelfinavir and stavudine and once-daily dida

  7. Comparison of two once-daily regimens with a regimen consisting of nelfinavir, didanosine, and stavudine in antiretroviral therapy-naive adults: 48-week results from the Antiretroviral Regimen Evaluation Study (ARES).

    NARCIS (Netherlands)

    Lowe, S.H.; Wensing, B.M.; Hassink, E.A.M.; Kate, R.W. ten; Richter, C.; Schreij, G.; Koopmans, P.P.; Juttmann, J.R.; Tweel, I. van de; Lange, J.M.A.; Borleffs, J.C.

    2005-01-01

    BACKGROUND: To improve the dosing frequency and pill burden of antiretroviral therapy, we compared two once-daily dosed regimens to a twice-daily dosed regimen. METHOD: HIV-1-infected, antiretroviral drug-naive adults were randomized to either twice-daily nelfinavir and stavudine and once-daily dida

  8. Labour induction with an intermediate-dose oxytocin regimen has advantages over a high-dose regimen.

    Science.gov (United States)

    Manjula, B G; Bagga, R; Kalra, J; Dutta, S

    2015-05-01

    A total of 200 women planned for labour induction were randomised to receive high-dose oxytocin (6 mU/min with similar increments every 45 min) or intermediate-dose oxytocin (3 mU/min with similar increments every 45 min). Oxytocin solution was prepared with 30 units in 500 ml saline with which the infusion rate in ml/h is numerically equal to oxytocin in mU/min. We observed that the caesarean rate (18% vs 6%, p = 0.009), contraction abnormalities (35% vs 14%, p = 0.0005) and neonatal bilirubin levels (7.99 ± 2.70 vs 6.80 ± 2.65, p = 0.002) were higher with high-dose than with intermediate-dose. The induction-delivery interval (IDI) was similar (10 h 13 min with high-dose and 11 h 5 min with intermediate-dose; p = 0.237, NS). Nulliparous women benefited more with intermediate-dose as the caesarean rate was higher with high-dose (24.6% vs 7.9%, p = 0.011). Although the caesarean rate was higher in multiparous women with high-dose oxytocin, it was statistically not significant (5.7% vs 2.7%; p = 0.609). Oxytocin regimens for labour induction are usually high-dose (4-6 mU/min) or low-dose (1-1.5 mU/min). The former is associated with more contraction abnormalities and the latter with prolonged IDI; both result in an increased caesarean rate. In order to offset these disadvantages, an intermediate- dose regimen was selected. The increment interval of 45 min was selected in accordance with the pharmacokinetics of oxytocin. We observed a lower caesarean rate when compared with the high-dose regimen, without any increase in the IDI. Hence, we propose that the intermediate-dose oxytocin regimen should be preferred to the high-dose regimen for labour induction.

  9. Reaction-transport-mechanical (RTM) simulator Sym.CS: Putting together water-rock interaction, multi-phase and heat flow, composite petrophysics model, and fracture mechanics

    Science.gov (United States)

    Paolini, C.; Park, A. J.; Mellors, R. J.; Castillo, J.

    2009-12-01

    A typical CO2 sequestration scenario involves the use of multiple simulators for addressing multiphase fluid and heat flow, water-rock interaction and mass-transfer, rock mechanics, and other chemical and physical processes. The benefit of such workflow is that each model can be constrained rigorously; however, the drawback is final modeling results may achieve only a limited extent of the theoretically possible capabilities of each model. Furthermore, such an approach in modeling carbon sequestration cannot capture the nonlinearity of the various chemical and physical processes. Hence, the models can only provide guidelines for carbon sequestration processes with large margins of error. As an alternative, a simulator is being constructed by a multi-disciplinary team with the aim of implementing a large array of fundamental phenomenologies, including, but not limited to: water-rock interaction using elemental mass-balance and explicit mass-transfer and reaction coupling methods; multi-phase and heat flow, including super-critical CO2 and oil; fracture mechanics with anisotropic permeabilities; rheological rock mechanics based on incremental stress theory; and a composite petrophysics model capable of describing changing rock composition and properties. The modules representing the processes will be solved using a layered iteration method, with the goal of capturing the nonlinear feedback among all of the processes. The simulator will be constructed using proven optimization and modular, object-oriented, and service-oriented programming methods. Finally, a novel AJAX (asynchronous JavaScript and XML) user interface is being tested to host the simulator that will allow usage through an Internet browser. Currently, the water-rock interaction, composite petrophysics, and multi-phase fluid and heat flow modules are available for integration. Results of the water-rock interaction and petrophysics coupling has been used to model interaction between a CO2-charged water and

  10. Thinking Critically about Critical Thinking

    Science.gov (United States)

    Mulnix, Jennifer Wilson

    2012-01-01

    As a philosophy professor, one of my central goals is to teach students to think critically. However, one difficulty with determining whether critical thinking can be taught, or even measured, is that there is widespread disagreement over what critical thinking actually is. Here, I reflect on several conceptions of critical thinking, subjecting…

  11. Predictors of nonadherence with blood pressure regimens in hemodialysis

    Directory of Open Access Journals (Sweden)

    Kauric-Klein Z

    2013-09-01

    Full Text Available Zorica Kauric-KleinCollege of Nursing, Wayne State University, Detroit, MI, USABackground: Hypertension is very poorly controlled in patients on hemodialysis (HD. Demographic and psychosocial predictors of nonadherence with blood pressure (BP regimens in HD have not been investigated. A study of 118 HD patients from six outpatient HD units was conducted to determine the relationship between demographic/psychosocial factors and adherence with BP-related regimens, ie, fluid restriction, BP medication adherence, and HD treatment adherence.Methods: Descriptive statistics, Pearson correlations, and multiple regressions were conducted to analyze and determine the relationships between variables.Results: Younger age was related to increased fluid gains (r = -0.37, P < 0.01, decreased medication adherence (r = -0.19, P = 0.04, increased missed HD treatments (r = -0.37, P < 0.01, and diastolic BP (r = -0.60, P < 0.01. Female sex was significantly related to decreased fluid gains (r = -0.28, P < 0.01. Race was related to increased missed HD treatments (r = 0.22, P = 0.02. Increased social support was related to decreased missed HD treatments (r = -0.22, P = 0.02. Depression scores were inversely related to decreased medication adherence scores (r = 0.24, P = 0.01.Conclusion: By identifying risk factors for nonadherence with BP-related regimens (young age, male sex, decreased social support, and depression, health care providers can plan early clinical intervention to minimize the risk of nonadherence.Keywords: nonadherence, hemodialysis, blood pressure, demographic predictors, psychosocial predictors

  12. Esquemas alternativos de hemodiálise Alternative hemodialysis regimens

    Directory of Open Access Journals (Sweden)

    Jorge Paulo Strogoff de Matos

    2010-03-01

    Full Text Available A taxa de mortalidade entre os pacientes em hemodiálise (HD é extremamente elevada. A expectativa de vida restante de um paciente ao iniciar HD é apenas cerca de um quarto daquela da população geral com a mesma idade. O esquema convencional de HD, com três sessões semanais de cerca de quatro horas, foi estabelecido de maneira empírica há cerca de quatro décadas e merece ser reavaliado criticamente. Desde a falha do Estudo HEMO em demonstrar benefícios clínicos com o aumento do Kt/V de ureia nos pacientes em esquema convencional de HD, tem havido um crescente interesse pelos esquemas alternativos de HD com o intuito de prover um tratamento associado com uma melhor sobrevida. Dentre os esquemas mais promissores, destacam-se a HD diária de curta duração e a HD noturna prolongada. As limitações econômicas que inibem a aplicação dos conhecimentos emergentes nesta área devem ser vencidas.The mortality rate among patients on hemodialysis (HD is extremely high. Remaining life expectancy for a patient initiating HD is only approximately one quarter of that of the general population at the same age bracket. The conventional HD regimen based on four-hour sessions three times a week was empirically established nearly four decades ago and needs to be revisited. Since the failure of the HEMO Study to demonstrate the clinical benefits of higher urea Kt/V for patients on conventional HD, an increasing interest for alternative HD regimens has emerged aiming at providing a treatment for improving survival rates. Short daily HD and long nocturnal HD stand out as the most promising alternative regimens. Economical obstacles which could hinder the clinical application of emerging knowledge in the field should be overcome.

  13. Effectiveness of multi-drug regimen chemotherapy treatment in osteosarcoma patients: a network meta-analysis of randomized controlled trials.

    Science.gov (United States)

    Wang, Xiaojie; Zheng, Hong; Shou, Tao; Tang, Chunming; Miao, Kun; Wang, Ping

    2017-03-29

    Osteosarcoma is the most common malignant bone tumour. Due to the high metastasis rate and drug resistance of this disease, multi-drug regimens are necessary to control tumour cells at various stages of the cell cycle, eliminate local or distant micrometastases, and reduce the emergence of drug-resistant cells. Many adjuvant chemotherapy protocols have shown different efficacies and controversial results. Therefore, we classified the types of drugs used for adjuvant chemotherapy and evaluated the differences between single- and multi-drug chemotherapy regimens using network meta-analysis. We searched electronic databases, including PubMed (MEDLINE), EmBase, and the Cochrane Library, through November 2016 using the keywords "osteosarcoma", "osteogenic sarcoma", "chemotherapy", and "random*" without language restrictions. The major outcome in the present analysis was progression-free survival (PFS), and the secondary outcome was overall survival (OS). We used a random effect network meta-analysis for mixed multiple treatment comparisons. We included 23 articles assessing a total of 5742 patients in the present systematic review. The analysis of PFS indicated that the T12 protocol (including adriamycin, bleomycin, cyclophosphamide, dactinomycin, methotrexate, cisplatin) plays a more critical role in osteosarcoma treatment (surface under the cumulative ranking (SUCRA) probability 76.9%), with a better effect on prolonging the PFS of patients when combined with ifosfamide (94.1%) or vincristine (81.9%). For the analysis of OS, we separated the regimens to two groups, reflecting the disconnection. The T12 protocol plus vincristine (94.7%) or the removal of cisplatinum (89.4%) is most likely the best regimen. We concluded that multi-drug regimens have a better effect on prolonging the PFS and OS of osteosarcoma patients, and the T12 protocol has a better effect on prolonging the PFS of osteosarcoma patients, particularly in combination with ifosfamide or vincristine

  14. Management of patients using unproven regimens for arthritis.

    Science.gov (United States)

    Wolman, P G

    1987-09-01

    Such treatments as vegetarian diets, fresh or raw diets, allergy diets, no-dairy-products diets, fasting, vitamin and mineral supplementation, apple cider vinegar, and honey drinks are touted in the popular press as effective for the treatment of arthritis. In contrast to conventional therapies, the unproven treatments promise not only relief from symptoms but freedom from the disease as long as the diet regimen is followed. Several of the remedies appear to be harmless, but others are dangerous, especially if followed for prolonged periods. Nutrition professionals should be aware of the nature of these treatments and be prepared to offer sound, scientifically based but nonjudgmental care and information.

  15. Establishment of TCM Standardized Therapeutic Regimen for Treating Tumor

    Institute of Scientific and Technical Information of China (English)

    林洪生

    2004-01-01

    @@ It has been of a long long history to treat tumor with traditional Chinese medicine (TCM), in the last 50years, Chinese medicine (CM) has been accepted by more and more medical professionals and patients, and used as one of the principal methods for treating tumor in China. But, tumor is a kind of disease with rapid progress and complicated causes, and applying CM in treating tumor has to meet some requirement, as improper application could induce contrary effects. To reduce the chance of blind and improper application of CM in the treatment of tumor, it is vital to work out a standardized therapeutic regimen that can be used as the guideline.

  16. Galeazzi fractures: our modified classification and treatment regimen.

    Science.gov (United States)

    Fayaz, H C; Jupiter, J B

    2014-02-01

    While diaphyseal fractures of the forearm are a common orthopedic injury, Galeazzi fractures are difficult to treat. The current knowledge on pathobiomechanics and modified therapeutic decisions implicate the need to devise an updated classification and treatment regimen of Galeazzi fractures. We challenge the concept that isolated fractures of the radius should be considered as a Galeazzi fractures as long as stability of the distal radioulnar joint is not proven. Contrary to others we demonstrate that the fracture location alone is not sufficient to determine the stability of the distal radioulnar joint. © Georg Thieme Verlag KG Stuttgart · New York.

  17. Adherence to diabetes regimens: empirical status and clinical applications.

    Science.gov (United States)

    Kurtz, S M

    1990-01-01

    Adherence to diabetes treatment regimens has proved to be a conceptual and empirical enigma. Consequently, reliable and valid applications to the clinical practice of diabetes care and education have been wanting. Rates of nonadherence are staggeringly high, regardless of the methodology employed, and verification of self-reports is complicated by social desirability to appear compliant. Low intertask correlations further complicate our understanding of adherence-metabolic control relationships. Studies relating to the Health Belief Model, social learning theory, and the psychology of interpersonal relationships that have sought to identify determinants of adherence behaviors have specific relevance to the clinical practice of diabetes education.

  18. Corticosteroid and calcineurin inhibitor sparing regimens in kidney transplantation.

    Science.gov (United States)

    Cortazar, Frank; Diaz-Wong, Roque; Roth, David; Isakova, Tamara

    2013-11-01

    Chronic kidney disease is a major public health problem that is associated with increased risks of kidney disease progression, cardiovascular disease and death. Kidney transplantation remains the renal replacement therapy of choice for patients with end-stage kidney disease. Despite impressive strides in short-term allograft survival, there has been little improvement in long-term kidney graft survival, and rates of death with a functioning allograft remain high. Long-term safety profiles of existing immunosuppressive regimens point to a need for continued search for alternative agents. This overview discusses emerging evidence on a few promising therapeutic approaches, juxtaposes conflicting findings and highlights remaining knowledge gaps.

  19. Simultaneous measurement of hysteresis in capillary pressure and electric permittivity for multiphase flow through porous media

    NARCIS (Netherlands)

    Plug, W.J.; Slob, E.C.; Bruining, J.; Moreno Tirado, L.M.

    2007-01-01

    We present a tool that simultaneously measures the complex permittivity and the capillary pressure characteristics for multiphase flow. The sample holder is a parallel plate capacitor. A precision component analyzer is used to measure the impedance amplitude and phase angle as a function of frequenc

  20. A Computational Model for Multi-phase Flow in a Heterogeneous Layered System (poster)

    NARCIS (Netherlands)

    Musivand Arzanfudi, M.

    2013-01-01

    CO2 sequestration in underground formations is currently utilized as a means to mitigate CO2 from indefinitely emitted to the atmosphere. The main concern in such a system is the possible occurrence of leakage to upper layers or to the earth surface. Computational modeling of leakage of a multiphase

  1. Construction of a Parallel Algorithm to Solve the Multiphase Gas Dynamics Problem

    Directory of Open Access Journals (Sweden)

    B. Rybakin

    1995-11-01

    Full Text Available This paper considers questions of an effective use of multiprocessor computing system to implement a parallel algorithm solving the multiphase gas dynamics problem. A technique is offered to parallelize the two-dimensional explicit differential scheme to implement it on multiprocessor systems with distributed memory (MIMD architecture.

  2. Use of the Minnesota Multiphasic Personality Inventory-2 with Persons Diagnosed with Multiple Sclerosis

    Science.gov (United States)

    Hayes, Danielle; Granello, Darcy Haag

    2009-01-01

    Counselors who assess persons with multiple sclerosis (MS) using the Minnesota Multiphasic Personality Inventory-2 (MMPI-2; T. N. Butcher, W. G. Dahlstrom, J. R. Graham, A. Tellegen, & B. Kaemmer, 1989) may find scale elevations on Scales 1, 2, 3, and 8. These elevations may be due, at least in part, to specific questions on the MMPI-2 that…

  3. Multiphasic pH profiles for the reaction of tris-(hydroxymethyl)-aminomethane with phenyl esters

    CERN Document Server

    Nissen, Per

    2015-01-01

    Reanalysis of data (Bruice and York 1961) for the pH dependences of the calculated apparent second-order rate constants (k2) for the reaction of tris-(hydroxymethyl)-aminomethane (TRIS) with phenyl esters reveals that the pH profiles are consistently much better represented as multiphasic, i.e. as a series of straight lines separated by discontinuities in the form of sharp breaks or noncontiguities (jumps), than by the continuous function used by the authors. For p-nitrophenyl acetate, m-nitrophenyl acetate, p-chlorophenyl acetate and phenyl acetate, the profiles are best represented as multiphasic in plots of log k2 vs. pH, whereas the profile for p-methylphenyl acetate is only multiphasic in a plot of k2 vs. pH. Data for the pseudo-first-order rate constants (kobs) give multiphasic pH profiles with patterns identical or very similar to those for k2. Extensive reanalyses of data for a wide variety of enzymatic and non-enzymatic reactions show, similarly, that pH profiles are in general better represented as ...

  4. Modelling of fluid-structure interaction with multiphase viscous flows using an immersed-body method

    Science.gov (United States)

    Yang, P.; Xiang, J.; Fang, F.; Pavlidis, D.; Latham, J.-P.; Pain, C. C.

    2016-09-01

    An immersed-body method is developed here to model fluid-structure interaction for multiphase viscous flows. It does this by coupling a finite element multiphase fluid model and a combined finite-discrete element solid model. A coupling term containing the fluid stresses is introduced within a thin shell mesh surrounding the solid surface. The thin shell mesh acts as a numerical delta function in order to help apply the solid-fluid boundary conditions. When used with an advanced interface capturing method, the immersed-body method has the capability to solve problems with fluid-solid interfaces in the presence of multiphase fluid-fluid interfaces. Importantly, the solid-fluid coupling terms are treated implicitly to enable larger time steps to be used. This two-way coupling method has been validated by three numerical test cases: a free falling cylinder in a fluid at rest, elastic membrane and a collapsing column of water moving an initially stationary solid square. A fourth simulation example is of a water-air interface with a floating solid square being moved around by complex hydrodynamic flows including wave breaking. The results show that the immersed-body method is an effective approach for two-way solid-fluid coupling in multiphase viscous flows.

  5. An experimental investigation of the multiphase flows in a photobioreactor for algae cultivation

    Science.gov (United States)

    Yang, Zifeng; Hu, Hui; Del Ninno, Matteo; Wen, Zhiyou

    2011-11-01

    Algal biomass is a promising feedstock for biofuels production, with photobioreactors being one of the major cultivation systems for algal cells. Light absorption, fluid dynamics, and algal metabolism are three key factors in determining the overall performance of a photobioreactor. The behavior of the multiphase flow (i.e., liquid phase - water, gas phase - CO2 and O2, and solid phase - algal cells) and turbulent mixing inside the reactor are the core connecting the three factors together. One of the major challenges in the optimal design of photobioreactors for algae cultivation is the lack of in-depth understanding of the characteristics of the multiphase flows and turbulent mixing. In this study, we present a comprehensive experimental study to investigate the effects of turbulent mixing in photobioreactors on the performance of a photobioreactor for algae cultivation. A high-resolution particle image velocity (PIV) system is used to achieve time-resolved, in-situ flow field measurements to quantify the turbulent mixing of the multiphase flows inside the bioreactor, while algal cultures are also grown in the same reactor with the same experimental settings. The mixing characteristics of the multiphase flow are correlated with the algal growth performance in the bioreactors to elucidate the underlying physics to explore/optimize design paradigms for the optimization of photobioreactor designs for algae cultivation.

  6. Use of the Minnesota Multiphasic Personality Inventory-2 with Persons Diagnosed with Multiple Sclerosis

    Science.gov (United States)

    Hayes, Danielle; Granello, Darcy Haag

    2009-01-01

    Counselors who assess persons with multiple sclerosis (MS) using the Minnesota Multiphasic Personality Inventory-2 (MMPI-2; T. N. Butcher, W. G. Dahlstrom, J. R. Graham, A. Tellegen, & B. Kaemmer, 1989) may find scale elevations on Scales 1, 2, 3, and 8. These elevations may be due, at least in part, to specific questions on the MMPI-2 that assess…

  7. Non-isothermal effects on multi-phase flow in porous medium

    DEFF Research Database (Denmark)

    Singh, Ashok; Wang, W; Park, C. H.

    2010-01-01

    In this paper a ppT -formulation for non-isothermal multi-phase flow is given including diffusion and latent heat effects. Temperature and pressure dependencies of governing parameters are considered, in particular surface tension variation on phase interfaces along with temperature changes. A weak...

  8. Modelling multiphase flow inside the porous media of a polymer electrolyte membrane fuel cell

    DEFF Research Database (Denmark)

    Berning, Torsten; Kær, Søren Knudsen

    2011-01-01

    Transport processes inside polymer electrolyte membrane fuel cells (PEMFC’s) are highly complex and involve convective and diffusive multiphase, multispecies flow through porous media along with heat and mass transfer and electrochemical reactions in conjunction with water transport through an el...

  9. Transmission Electron Microscopy Specimen Preparation Method for Multiphase Porous Functional Ceramics

    DEFF Research Database (Denmark)

    Zhang, Wei; Kuhn, Luise Theil; Jørgensen, Peter Stanley

    2013-01-01

    An optimum method is proposed to prepare thin foil transmission electron microscopy (TEM) lamellae of multiphase porous functional ceramics: prefilling the pore space of these materials with an epoxy resin prior to focused ion beam milling. Several advantages of epoxy impregnation are demonstrate...

  10. Use of the Minnesota Multiphasic Personality Inventory-2 with Persons Diagnosed with Multiple Sclerosis

    Science.gov (United States)

    Hayes, Danielle; Granello, Darcy Haag

    2009-01-01

    Counselors who assess persons with multiple sclerosis (MS) using the Minnesota Multiphasic Personality Inventory-2 (MMPI-2; T. N. Butcher, W. G. Dahlstrom, J. R. Graham, A. Tellegen, & B. Kaemmer, 1989) may find scale elevations on Scales 1, 2, 3, and 8. These elevations may be due, at least in part, to specific questions on the MMPI-2 that…

  11. THE RATE-INDEPENDENT CONSTITUTIVE MODELING FOR POROUS AND MULTI-PHASE NANOCRYSTALLINE MATERIAL

    Institute of Scientific and Technical Information of China (English)

    Zhou Jianqiu; Li Yuanling; Zhang Zhenzhong

    2007-01-01

    To determine the time-independent constitutive modeling for porous and multiphase nanocrystalline materials and understand the effects of grain size and porosity on their mechanical behavior, each phase was treated as a mixture of grain interior and grain boundary, and pores were taken as a single phase, then Budiansky's self-consistent method was used to calculate the Young's modulus of porous, possible multi-phase, nanocrystalline materials, the prediction being in good agreement with the results in the literature. Further, the established method is extended tosimulate the constitutive relations of porous and possible multi-phase nanocrystalline materials with small plastic deformation in conjunction with the secant-moduli approach and iso-strain assumption. Comparisons between the experimental grain size and porosity dependent mechanical data and the corresponding predictions using the established model show that it appears to be capable of describing the time-independent mechanical behaviors for porous and multi-phase nanocrystalline materials in a small plastic strain range. Further discussion on the modification factor, the advantages and limitations of the model developed were present.

  12. Low-Jitter Multi-phase Clock Generation: a Comparison between DLLs and Shift Registers

    NARCIS (Netherlands)

    Gao, X.; Klumperink, E.A.M.; Nauta, B.

    2007-01-01

    This paper shows that, for a given power budget, a shift register based multi-phase clock generator (MPCG) generates less jitter than a delay-locked loop (DLL) equivalent when both are realized with current mode logic (CML) circuits and white noise is assumed. This is due to the factor that the shif

  13. Advantages of Shift Registers over DLLs for Flexible Low Jitter Multiphase Clock Generation

    NARCIS (Netherlands)

    Gao, Xiang; Klumperink, Eric A.M.; Nauta, Bram

    2008-01-01

    In this paper, we compare a shift register (SR) to a delay-locked loop (DLL) for flexible multiphase clock generation, and motivate why a SR is not only more flexible but often also better. For a given power budget, we show that a SR almost always generates less jitter than a DLL, assuming both are

  14. Design and Construction of a Shock Tube Experiment for Multiphase Instability Experiments

    Science.gov (United States)

    Middlebrooks, John; Black, Wolfgang; Avgoustopoulos, Constantine; Allen, Roy; Kathakapa, Raj; Guo, Qiwen; McFarland, Jacob

    2016-11-01

    Hydrodynamic instabilities are important phenomena that have a wide range of practical applications in engineering and physics. One such instability, the shock driven multiphase instability (SDMI), arises when a shockwave accelerates an interface between two particle-gas mixtures with differing multiphase properties. The SDMI is present in high energy explosives, scramjets, and supernovae. A practical way of studying shock wave driven instabilities is through experimentation in a shock tube laboratory. This poster presentation will cover the design and data acquisition process of the University of Missouri's Fluid Mixing Shock Tube Laboratory. In the shock tube, a pressure generated shockwave is passed through a multiphase interface, creating the SDMI instability. This can be photographed for observation using high speed cameras, lasers, and advance imaging techniques. Important experimental parameters such as internal pressure and temperature, and mass flow rates of gases can be set and recorded by remotely controlled devices. The experimental facility provides the University of Missouri's Fluid Mixing Shock Tube Laboratory with the ability to validate simulated experiments and to conduct further inquiry into the field of shock driven multiphase hydrodynamic instabilities. Advisor.

  15. Dynamics of multiphase systems with complex microstructure. I. Development of the governing equations through nonequilibrium thermodynamics

    NARCIS (Netherlands)

    Sagis, L.M.C.; Öttinger, H.C.

    2013-01-01

    In this paper we present a general model for the dynamic behavior of multiphase systems in which the bulk phases and interfaces have a complex microstructure (for example, immiscible polymer blends with added compatibilizers, or polymer stabilized emulsions with thickening agents dispersed in the co

  16. CONTINOUS MULTI-PHASE FLOW REACTOR FOR SMALL AND LARGE FLOW CAPACITIES THAN L/MIN

    NARCIS (Netherlands)

    Al-Rawashdeh, Ma'moun; Schouten, Jaap; Nijhuis, T. Alexander; Yue, Jun

    2014-01-01

    Multiphase flow processing in flow reactors holds great promises for diverse applications in fine chemicals and materials synthesis primarily due to its precise control over the flow, mixing and reaction inside or between each phase. Even though, flow reactors have shown superior performance, so far

  17. Multiscale Structure-Performance Relationships in Supported Palladium Catalysis for Multiphase Hydrogenations

    NARCIS (Netherlands)

    Bakker, J.J.W.

    2012-01-01

    The performance of heterogeneous catalysts in multiphase reactions in general is governed by different types of extrinsic and intrinsic structural effects on all length scales, i.e., on the macro- (m to cm), meso- (mm to µm), and microlevel (nm). This PhD research, with a catalysis-engineering appro

  18. Forces on bends and T-joints due to multiphase flow

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Cargnelutti, M.F.; Schiferli, W.; Osch, M.M.E. van

    2010-01-01

    To be able to assess the mechanical integrity of piping structures for loading to multiphase flow conditions, air-water experiments were carried out in a horizontal 1" pipe system. Forces and accelerations were measured on a number of bends and T-joint configurations for a wide range of operating co

  19. Drift sands, lakes, and soils: the multiphase Holocene history of the Laarder Wasmeren area near Hilversum

    NARCIS (Netherlands)

    Sevink, J.; Koster, E.A.; van Geel, B.; Wallinga, J.

    2013-01-01

    A unique complex of multiphased Holocene drift sands and paleosols, with at least two lacustrine phases, was discovered during a major sanitation project in the Laarder Wasmeren area near Hilversum, the Netherlands. The complex could be studied in detail, highly facilitated by the excellent and larg

  20. Forces on bends and T-joints due to multiphase flow

    NARCIS (Netherlands)

    Belfroid, S.P.C.; Cargnelutti, M.F.; Schiferli, W.; Osch, M.M.E. van

    2010-01-01

    To be able to assess the mechanical integrity of piping structures for loading to multiphase flow conditions, air-water experiments were carried out in a horizontal 1" pipe system. Forces and accelerations were measured on a number of bends and T-joint configurations for a wide range of operating

  1. Multi-phase flow modeling of soil contamination and soil remediation.

    NARCIS (Netherlands)

    Dijke, van M.I.J.

    1997-01-01

    In this thesis multi-phase flow models are used to study the flow behavior of liquid contaminants in aquifers and of gases that are injected below the groundwater table for remediation purposes. Considered problems are redistribution of a lens of light nonaqueous phase liquid(LNAPL)on a hor

  2. Capabilities of Numerical Simulation of Multiphase Flows in Centrifugal Pumps using Modern CFD Software

    CERN Document Server

    Kochevsky, A N

    2005-01-01

    The paper describes capabilities of numerical simulation of liquid flows with solid and/or gas admixtures in centrifugal pumps using modern commercial CFD software packages, with the purpose to predict performance curves of the pumps treating such media. In particular, the approaches and multiphase flow models available in the package CFX-5 are described; their advantages and disadvantages are analyzed.

  3. Mitigation of Lower Order Harmonics with Filtered Svpwm In Multiphase Voltage Source Inverters

    Directory of Open Access Journals (Sweden)

    K. Uday Kiran

    2014-08-01

    Full Text Available Multi-phase machines and drives is a topic of growing relevance in recent years, and it presents many challenging issues that still need further research. This is the case of multi-phase space vector pulse width modulation (SVPWM, which shows not only more space vectors than the standard three-phase case, but also new subspaces where the space vectors are mapped. In the digital implementation, multiphase reference voltages are sampled and fed into the digital modulator to produce gating signals at a constant clock rate f. This means a finite pulse-width resolution because the gating state transition can only occur at some specific time instants depending on frequency. This results in a deviation of produced phase voltages from the desired phase voltages, i.e., increasing harmonic distortion especially for a small modulation index signal. In the present paper a filtered space-vector pulse-width modulation (SVPWM considering finite pulse-width resolution is proposed to produce a switching sequence with reduced baseband harmonics for multiphase voltage source inverters (VSI. This is achieved by incorporating a pseudo feedback loop regarding weighted voltage difference between desired and produced phase voltages.

  4. MULTI-REGION SEGMENTATION OF SAR IMAGE BY A MULTIPHASE LEVEL SET APPROACH

    Institute of Scientific and Technical Information of China (English)

    Fu Yusheng; Cao Zongjie; Pi Yiming

    2008-01-01

    In this letter, a multiphase level set approach unifying region and boundary-based infor- mation for multi-region segmentation of Synthetic Aperture Radar (SAR) image is presented. An energy functional that is applicable for SAR image segmentation is defined. It consists of two terms describing the local statistic characteristics and the gradient characteristics of SAR image respectively. A multiphase level set model that explicitly describes the different regions in one image is proposed. The purpose of such a multiphase model is not only to simplify the way of denoting multi-region by level set but also to guarantee the accuracy of segmentation. According to the presented multiphase model, the curve evolution equations with respect to edge curves are deduced. The multi-region segmentation is implemented by the numeric solution of the partial differential equations. The performance of the approach is verified by both simulation and real SAR images. The experiments show that the proposed algorithm reduces the speckle effect on segmentation and increases the boundary alignment accuracy, thus correctly divides the multi-region SAR image into different homogenous regions.

  5. RECENT ADVANCES IN STUDIES ON MULTIPHASE AND REACTING FLOWS IN CHINA

    Institute of Scientific and Technical Information of China (English)

    周力行

    2002-01-01

    The recent developments and advances of studies on multiphase and reacting flows, including gas-solid, gas-liquid, liquid-solid and reacting flows, in China are reviewed. Special emphasis is laid on the fundamental studies and numerical models. Some important experimental results are also reported. But measurement techniques are not covered.

  6. CONTINOUS MULTI-PHASE FLOW REACTOR FOR SMALL AND LARGE FLOW CAPACITIES THAN L/MIN

    NARCIS (Netherlands)

    Al-Rawashdeh, Ma'moun; Schouten, Jaap; Nijhuis, T. Alexander; Yue, Jun

    2014-01-01

    Multiphase flow processing in flow reactors holds great promises for diverse applications in fine chemicals and materials synthesis primarily due to its precise control over the flow, mixing and reaction inside or between each phase. Even though, flow reactors have shown superior performance, so far

  7. Multiphase boosting: A growing technology for the challenge of economical deepwater developments

    Energy Technology Data Exchange (ETDEWEB)

    Colombi, P. [Agip S.p.A., Milan (Italy); Chiesa, G. [Snamprogetti S.p.A., Milan (Italy); Aggradi, G.F. [Nuovo Pignone, Florence (Italy)

    1996-12-31

    The current operating success in the subsea prototype testing and the level of development of different pump concepts are promoting multiphase boosting as a reliable technology for the exploitation of subsea fields. From a situation where very basic questions were asked about the expected performance and reliability of this equipment the Industry is now looking at those scenarios showing the greatest potential for the application of this technology like the deep waters. Competitive options to develop subsea fields, however, may be available and, although they may present some disadvantages compared with multiphase boosting, they make use of traditional practices and proven technologies. In the above perspective, the field operational experience plays a key role to prove the suitability of the proposed systems in handling the untreated well fluids under real subsea conditions so giving multiphase boosting a distinct edge over more conventional solutions. To this end, the paper reviews the main results obtained so far by the underwater testing campaign of a prototype multiphase boosting unit at the Agip Prezioso Field, offshore Sicily. In particular, the review addresses the main technological issues encountered during the subsea operation of the boosting unit together with an initial characterization of the experienced unit performance. The above is considered to provide a significant contribution to the evaluation of the current level of maturity of this technology as well as of the present technological gap to meet the requirements posed by real industrial applications, particularly in deep waters.

  8. Gas-to-liquids process using multi-phase flow, non-thermal plasma microreactor

    NARCIS (Netherlands)

    Agiral, Anil; Nozaki, Tomohiro; Nakase, Masahiko; Yuzawa, Shuhei; Okazaki, Ken; Gardeniers, J.G.E. (Han)

    2011-01-01

    A multi-phase flow non-thermal plasma microreactor based on dielectric barrier discharge has been developed for partial oxidation of methane to liquid oxygenates at atmospheric pressure. A pulsed water injection method has been used to remove condensable liquid components from the active discharge r

  9. Proposed Novel Multiphase-Multilevel Inverter Configuration for Open-End Winding Loads

    DEFF Research Database (Denmark)

    Padamanaban, Sanjeevi Kumar; Wheeler, Patrick; Blaabjerg, Frede

    2016-01-01

    This paper presents a new multiphase-multilevel inverter configuration for open-winding loads and suitable for medium power (low-voltage/high-current) applications such as `More Electric Aircraft'. Modular structure comprised of standard dual three-phase voltage source inverter (VSI) along with o...

  10. Critical Care

    Science.gov (United States)

    Critical care helps people with life-threatening injuries and illnesses. It might treat problems such as complications ... a team of specially-trained health care providers. Critical care usually takes place in an intensive care ...

  11. Recent advances in tuberculosis: New drugs and treatment regimens.

    Science.gov (United States)

    Sloan, Derek J; Davies, Geraint R; Khoo, Saye H

    2013-06-01

    The current treatment regimen against drug susceptible tuberculosis (DS-TB) was defined by the 1980s. Since then the emergence of the global HIV pandemic and the escalation of drug resistant (DR-) forms of TB have presented new challenges for therapeutic research. Priority goals include shortening DS-TB treatment, improving DR-TB treatment and making combined TB-HIV therapy easier. To help achieve these goals, a range of new drugs and treatment strategies are currently being evaluated. Phase IIb and III clinical trials are ongoing to assess combinations involving the high-dose rifamycins, the 8-methoxyquinolones, a diarylquinoline (bedaquiline) and the nitroimidazoles. Other compounds (e.g. novel oxazolidinones and ethylenediamines) are at earlier stages of clinical development. Overall, there are grounds for optimism that recent advances will contribute towards achievement of new treatment regimens in the foreseeable future. However, long-term investment, political commitment and scientific endeavour are crucial to ensure that progress is sustained and the benefits of recent advances reach those in the greatest need.

  12. Postcesarean Thromboprophylaxis with Two Different Regimens of Bemiparin

    Directory of Open Access Journals (Sweden)

    Milagros Cruz

    2011-01-01

    Full Text Available Objectives. To compare the effectiveness of postcesarean thromboprophylaxis with two different regimens of bemiparin. Material and Methods. The study included 646 women with cesarean delivery in our hospital within a 1-year period, randomly assigned to one of two groups for prophylaxis with 3500 IU bemiparin once daily for 5 days or 3500 IU bemiparin once daily for 10 days. Results. There was one case of pulmonary embolism (first day following cesarean. An additional risk factor was present in 98.52% of the women, most frequently emergency cesarean, anemia, or obesity. The only risk factors for thromboembolic disease significantly related to pulmonary thromboembolism were placental abruption and prematurity. There were no differences in thromboembolic events among the two thromboprophylaxis regimens. Conclusions. Cesarean-related thromboembolic events were reduced in our study population due to the thromboprophylactic measures taken. Thromboprophylaxis with 3500 IU bemiparin once daily for 5 days following cesarean was sufficient to avoid thromboembolic events.

  13. Archetypal Criticism.

    Science.gov (United States)

    Chesebro, James W.; And Others

    1990-01-01

    Argues that archetypal criticism is a useful way of examining universal, historical, and cross-cultural symbols in classrooms. Identifies essential features of an archetype; outlines operational and critical procedures; illustrates archetypal criticism as applied to the cross as a symbol; and provides a synoptic placement for archetypal criticism…

  14. Evaluation of the atmospheric significance of multiphase reactions in atmospheric secondary organic aerosol formation

    Directory of Open Access Journals (Sweden)

    Gelencsér

    2005-01-01

    Full Text Available In a simple conceptual cloud-aerosol model the mass of secondary organic aerosol (SOA that may be formed in multiphase reaction in an idealized scenario involving two cloud cycles separated with a cloud-free period is evaluated. The conditions are set to those typical of continental clouds, and each parameter used in the model calculations is selected as a mean of available observational data of individual species for which the multiphase SOA formation route has been established. In the idealized setting gas and aqueous-phase reactions are both considered, but only the latter is expected to yield products of sufficiently low volatility to be retained by aerosol particles after the cloud dissipates. The key variable of the model is the Henry-constant which primarily determines how important multiphase reactions are relative to gas-phase photooxidation processes. The precursor considered in the model is assumed to already have some affinity to water, i.e. it is a compound having oxygen-containing functional group(s. As a principal model output an aerosol yield parameter is calculated for the multiphase SOA formation route as a function of the Henry-constant, and has been found to be significant already above H~103 M atm-1. Among the potential precursors that may be eligible for this mechanism based on their Henry constants, there are a suite of oxygenated compounds such as primary oxidation products of biogenic and anthropogenic hydrocarbons, including, for example, pinonaldehyde. Finally, the analogy of multiphase SOA formation to in-cloud sulfate production is exploited.

  15. Novel and Effective Therapeutic Regimens for Helicobacter pylori in an Era of Increasing Antibiotic Resistance

    Directory of Open Access Journals (Sweden)

    Yi Hu

    2017-05-01

    Full Text Available Helicobacter pylori (H. pylori is a common gastrointestinal bacterial strain closely associated with the incidence of chronic gastritis, peptic ulcers, gastric mucosa-associated lymphoid tissue lymphoma, and gastric cancer. A current research and clinical challenge is the increased rate of antibiotic resistance in H. pylori, which has led to a decreased H. pylori eradication rate. In this article, we review recent H. pylori infection and reinfection rates and H. pylori resistance to antibiotics, and we discuss the pertinent treatments. A PubMed literature search was performed using the following keywords: Helicobacter pylori, infection, reinfection, antibiotic resistance, bismuth, proton pump inhibitors, vonoprazan, susceptibility, quintuple therapy, dual therapy, and probiotic. The prevalence of H. pylori has remained high in some areas despite the decreasing trend of H. pylori prevalence observed over time. Additionally, the H. pylori reinfection rate has varied in different countries due to socioeconomic and hygienic conditions. Helicobacter pylori monoresistance to clarithromycin, metronidazole or levofloxacin was common in most countries. However, the prevalence of amoxicillin and tetracycline resistance has remained low. Because H. pylori infection and reinfection present serious challenges and because H. pylori resistance to clarithromycin, metronidazole or levofloxacin remains high in most countries, the selection of an efficient regimen to eradicate H. pylori is critical. Currently, bismuth-containing quadruple therapies still achieve high eradication rates. Moreover, susceptibility-based therapies are alternatives because they may avoid the use of unnecessary antibiotics. Novel regimens, e.g., vonoprazan-containing triple therapies, quintuple therapies, high-dose dual therapies, and standard triple therapies with probiotics, require further studies concerning their efficiency and safety for treating H. pylori.

  16. Novel and Effective Therapeutic Regimens for Helicobacter pylori in an Era of Increasing Antibiotic Resistance

    Science.gov (United States)

    Hu, Yi; Zhu, Yin; Lu, Nong-Hua

    2017-01-01

    Helicobacter pylori (H. pylori) is a common gastrointestinal bacterial strain closely associated with the incidence of chronic gastritis, peptic ulcers, gastric mucosa-associated lymphoid tissue lymphoma, and gastric cancer. A current research and clinical challenge is the increased rate of antibiotic resistance in H. pylori, which has led to a decreased H. pylori eradication rate. In this article, we review recent H. pylori infection and reinfection rates and H. pylori resistance to antibiotics, and we discuss the pertinent treatments. A PubMed literature search was performed using the following keywords: Helicobacter pylori, infection, reinfection, antibiotic resistance, bismuth, proton pump inhibitors, vonoprazan, susceptibility, quintuple therapy, dual therapy, and probiotic. The prevalence of H. pylori has remained high in some areas despite the decreasing trend of H. pylori prevalence observed over time. Additionally, the H. pylori reinfection rate has varied in different countries due to socioeconomic and hygienic conditions. Helicobacter pylori monoresistance to clarithromycin, metronidazole or levofloxacin was common in most countries. However, the prevalence of amoxicillin and tetracycline resistance has remained low. Because H. pylori infection and reinfection present serious challenges and because H. pylori resistance to clarithromycin, metronidazole or levofloxacin remains high in most countries, the selection of an efficient regimen to eradicate H. pylori is critical. Currently, bismuth-containing quadruple therapies still achieve high eradication rates. Moreover, susceptibility-based therapies are alternatives because they may avoid the use of unnecessary antibiotics. Novel regimens, e.g., vonoprazan-containing triple therapies, quintuple therapies, high-dose dual therapies, and standard triple therapies with probiotics, require further studies concerning their efficiency and safety for treating H. pylori. PMID:28529929

  17. Sowing the "Semillas" of Critical Multicultural Citizenship for Latina/o Undocumented Youth: Spaces in School and out of School

    Science.gov (United States)

    Salazar, Maria del Carmen; Martinez, Lisa M.; Ortega, Debora

    2016-01-01

    The purpose of this study is to address how spaces in school and out of school support or constrain undocumented Latina/o youths' development as critical multicultural citizens. We draw on data from a multi-phase, qualitative study to present findings indicating that the youths persevered through academic and civic engagement. Ultimately, the…

  18. How Critical Is Critical Thinking?

    Science.gov (United States)

    Shaw, Ryan D.

    2014-01-01

    Recent educational discourse is full of references to the value of critical thinking as a 21st-century skill. In music education, critical thinking has been discussed in relation to problem solving and music listening, and some researchers suggest that training in critical thinking can improve students' responses to music. But what exactly is…

  19. Different antibiotic regimens for treating asymptomatic bacteriuria in pregnancy.

    Science.gov (United States)

    Guinto, Valerie T; De Guia, Blanca; Festin, Mario R; Dowswell, Therese

    2010-09-08

    Asymptomatic bacteriuria occurs in 5% to 10% of pregnancies and, if left untreated, can lead to serious complications. To assess which antibiotic is most effective and least harmful as initial treatment for asymptomatic bacteriuria in pregnancy. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (March 2010) and reference lists of retrieved studies. Randomized controlled trials comparing two antibiotic regimens for treating asymptomatic bacteriuria. Review authors independently screened the studies for inclusion and extracted data. We included five studies involving 1140 women with asymptomatic bacteriuria. We did not perform meta-analysis; each trial examined different antibiotic regimens and so we were not able to pool results. In a study comparing a single dose of fosfomycin trometamol 3 g with a five-day course of cefuroxime, there was no significant difference in persistent infection (risk ratio (RR) 1.36, 95% confidence interval (CI) 0.24 to 7.75), shift to other antibiotics (RR 0.08, 95% CI 0.00 to 1.45), or in allergy or pruritus (RR 2.73, 95% CI 0.11 to 65.24). A comparison of seven-day courses of 400 mg pivmecillinam versus 500 mg ampicillin, both given four times daily, showed no significant difference in persistent infection at two weeks or recurrent infection, but there was an increase in vomiting (RR 4.57, 95% CI 1.40 to 14.90) and women were more likely to stop treatment early with pivmecillinam (RR 8.82, 95% CI 1.16 to 66.95). When cephalexin 1 g versus Miraxid(R) (pivmecillinam 200 mg and pivampicillin 250 mg) were given twice-daily for three days, there was no significant difference in persistent or recurrent infection. A one- versus seven-day course of nitrofurantoin resulted in more persistent infection with the shorter course (RR 1.76, 95% CI 1.29 to 2.40), but no significant difference in symptomatic infection at two weeks, nausea, or preterm birth. Comparing cycloserine with sulphadimidine, no significant differences in

  20. Switching regimens in virologically suppressed HIV-1-infected patients: evidence base and rationale for integrase strand transfer inhibitor (INSTI)-containing regimens.

    Science.gov (United States)

    Raffi, F; Esser, S; Nunnari, G; Pérez-Valero, I; Waters, L

    2016-10-01

    In an era when most individuals with treated HIV infection can expect to live into old age, clinicians should proactively review their patients' current and future treatment needs and challenges. Clinical guidelines acknowledge that, in the setting of virological suppression, treatment switch may yield benefits in terms of tolerability, regimen simplification, adherence, convenience and long-term health considerations, particularly in the context of ageing. In this paper, we review evidence from six key clinical studies on switching virologically suppressed patients to regimens based on integrase strand transfer inhibitors (INSTIs), the antiretroviral class increasingly preferred as initial therapy in clinical guidelines. We review these studies and focus on the virological efficacy, safety, and tolerability of switching to INSTI-based regimens in suppressed HIV-positive individuals. We review the early switch studies SWITCHMRK and SPIRAL [assessing a switch from a ritonavir-boosted protease inhibitor (PI/r) to raltegravir (RAL)-containing regimens], together with data from STRATEGY-PI [assessing a switch to elvitegravir (EVG)-containing regimens; EVG/cobicistat (COBI)/emtricitabine (FTC)/tenofovir disoproxil fumarate (TDF) vs. remaining on a PI/r-containing regimen], STRATEGY-NNRTI [assessing a switch to EVG/COBI/FTC/TDF vs. continuation of a nonnucleoside reverse transcriptase inhibitor (NNRTI) and two nucleoside reverse transcriptase inhibitors (NRTIs)], STRIIVING [assessing a switch to a dolutegravir (DTG)-containing regimen (abacavir (ABC)/lamivudine (3TC)/DTG) vs. staying on the background regimen], and GS study 109 [assessing a switch to EVG/COBI/FTC/tenofovir alafenamide fumarate (TAF) vs. continuation of FTC/TDF-based regimens]. Switching to INSTI-containing regimens has been shown to support good virological efficacy, with evidence from two studies demonstrating superior virological efficacy for a switch to EVG-containing regimens. In addition, switching

  1. Effects of intravenous fluid restriction on postoperative complications: comparison of two perioperative fluid regimens: a randomized assessor-blinded multicenter trial

    DEFF Research Database (Denmark)

    Brandstrup, Birgitte; Tønnesen, Hanne; Beier-Holgersen, Randi;

    2003-01-01

    To investigate the effect of a restricted intravenous fluid regimen versus a standard regimen on complications after colorectal resection.......To investigate the effect of a restricted intravenous fluid regimen versus a standard regimen on complications after colorectal resection....

  2. Online recognition of the multiphase flow regime and study of slug flow in pipeline

    Science.gov (United States)

    Liejin, Guo; Bofeng, Bai; Liang, Zhao; Xin, Wang; Hanyang, Gu

    2009-02-01

    Multiphase flow is the phenomenon existing widely in nature, daily life, as well as petroleum and chemical engineering industrial fields. The interface structure among multiphase and their movement are complicated, which distribute random and heterogeneously in the spatial and temporal scales and have multivalue of the flow structure and state[1]. Flow regime is defined as the macro feature about the multiphase interface structure and its distribution, which is an important feature to describe multiphase flow. The energy and mass transport mechanism differ much for each flow regimes. It is necessary to solve the flow regime recognition to get a clear understanding of the physical phenomena and their mechanism of multiphase flow. And the flow regime is one of the main factors affecting the online measurement accuracy of phase fraction, flow rate and other phase parameters. Therefore, it is of great scientific and technological importance to develop new principles and methods of multiphase flow regime online recognition, and of great industrial background. In this paper, the key reasons that the present method cannot be used to solve the industrial multiphase flow pattern recognition are clarified firstly. Then the prerequisite to realize the online recognition of multiphase flow regime is analyzed, and the recognition rules for partial flow pattern are obtained based on the massive experimental data. The standard templates for every flow regime feature are calculated with self-organization cluster algorithm. The multi-sensor data fusion method is proposed to realize the online recognition of multiphase flow regime with the pressure and differential pressure signals, which overcomes the severe influence of fluid flow velocity and the oil fraction on the recognition. The online recognition method is tested in the practice, which has less than 10 percent measurement error. The method takes advantages of high confidence, good fault tolerance and less requirement of

  3. Non-equilibrium processes in ash-laden volcanic plumes: new insights from 3D multiphase flow simulations

    Science.gov (United States)

    Esposti Ongaro, Tomaso; Cerminara, Matteo

    2016-10-01

    In the framework of the IAVCEI (International Association of Volcanology and Chemistry of the Earth Interior) initiative on volcanic plume models intercomparison, we discuss three-dimensional numerical simulations performed with the multiphase flow model PDAC (Pyroclastic Dispersal Analysis Code). The model describes the dynamics of volcanic and atmospheric gases (in absence of wind) and two pyroclastic phases by adopting a non-equilibrium Eulerian-Eulerian formulation. Accordingly, gas and particulate phases are treated as interpenetrating fluids, interacting with each other through momentum (drag) and heat exchange. Numerical results describe the time-wise and spatial evolution of weak (mass eruption rate: 1.5 × 106 kg/s) and strong (mass eruption rate: 1.5 × 109 kg/s) plumes. The two tested cases display a remarkably different phenomenology, associated with the different roles of atmospheric stratification, compressibility and mechanism of buoyancy reversal, reflecting in a different structure of the plume, of the turbulent eddies and of the atmospheric circulation. This also brings about different rates of turbulent mixing and atmospheric air entrainment. The adopted multiphase flow model allows to quantify temperature and velocity differences between the gas and particles, including settling, preferential concentration by turbulence and thermal non-equilibrium, as a function of their Stokes number, i.e., the ratio between their kinetic equilibrium time and the characteristic large-eddy turnover time of the turbulent plume. As a result, the spatial and temporal distribution of coarse ash in the atmosphere significantly differs from that of the fine ash, leading to a modification of the plume shape. Finally, three-dimensional numerical results have been averaged in time and across horizontal slices in order to obtain a one-dimensional picture of the plume in a stationary regime. For the weak plume, the results are consistent with one-dimensional models, at

  4. Toward the definition of immunosuppressive regimens with antitumor activity.

    Science.gov (United States)

    Casadio, F; Croci, S; D'Errico Grigioni, A; Corti, B; Grigioni, W F; Landuzzi, L; Lollini, P-L

    2005-06-01

    Immunosuppressive therapies associated with organ transplantation produce an increased risk of cancer development. Malignancies are increased in transplant recipients because of the impaired immune system. Moreover, experimental data point to a tumor-promoting activity of various immunosuppressive agents. In this study, we compared the effects of 4 immunosuppressive agents with different mechanisms of action (cyclosporine, rapamycin, mycophenolic acid, and leflunomide) on the in vitro growth of various tumor cell lines and umbilical vein endothelial cells. To varying degrees rapamycin (10 ng/mL), mycophenolic acid (300 nmol/L), and leflunomide (30 micromol/L) highly inhibited the growth of human rhabdomyosarcoma, hepatocellular carcinoma, colorectal carcinoma, and endothelial cells. In contrast, cyclosporine (100 ng/mL) did not affect their growth. Our data suggest that regimens containing rapamycin, mycophenolic acid, or leflunomide, which have both immunosuppressive and antitumor activities, should be preferred in transplant recipients to minimize the risk of tumors.

  5. Medication regimen complexity in ambulatory older adults with heart failure

    Directory of Open Access Journals (Sweden)

    Cobretti MR

    2017-04-01

    Full Text Available Michael R Cobretti,1 Robert L Page II,2 Sunny A Linnebur,2 Kimberly M Deininger,1 Amrut V Ambardekar,3 JoAnn Lindenfeld,4 Christina L Aquilante1 1Department of Pharmaceutical Sciences, 2Department of Clinical Pharmacy, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO, 3Division of Cardiology, School of Medicine, University of Colorado, Aurora, CO, 4Advanced Heart Failure and Cardiac Transplant Program, Vanderbilt Heart and Vascular Institute, Nashville, TN, USA Purpose: Heart failure prevalence is increasing in older adults, and polypharmacy is a major problem in this population. We compared medication regimen complexity using the validated patient-level Medication Regimen Complexity Index (pMRCI tool in “young-old” (60–74 years versus “old-old” (75–89 years patients with heart failure. We also compared pMRCI between patients with ischemic cardiomyopathy (ISCM versus nonischemic cardiomyopathy (NISCM.Patients and methods: Medication lists were retrospectively abstracted from the electronic medical records of ambulatory patients aged 60–89 years with heart failure. Medications were categorized into three types – heart failure prescription medications, other prescription medications, and over-the-counter (OTC medications – and scored using the pMRCI tool.Results: The study evaluated 145 patients (n=80 young-old, n=65 old-old, n=85 ISCM, n=60 NISCM, mean age 73±7 years, 64% men, 81% Caucasian. Mean total pMRCI scores (32.1±14.4, range 3–84 and total medication counts (13.3±4.8, range 2–30 were high for the entire cohort, of which 72% of patients were taking eleven or more total medications. Total and subtype pMRCI scores and medication counts did not differ significantly between the young-old and old-old groups, with the exception of OTC medication pMRCI score (6.2±4 young-old versus 7.8±5.8 old-old, P=0.04. With regard to heart failure etiology, total pMRCI scores and medication

  6. Comparison of different anthelminthic drug regimens against Mansonella perstans filariasis.

    Science.gov (United States)

    Bregani, Enrico Rino; Rovellini, Angelo; Mbaïdoum, Narassem; Magnini, Maria Giovanna

    2006-05-01

    Mansonella perstans filariasis is widely present in Africa and equatorial America and its pathogenicity has recently been reconsidered. Effective treatment is lacking and there is no consensus on the optimal therapeutic approach. The aim of this study was to compare the effects of different drug regimens on M. perstans infection. Six different anthelminthic therapeutic protocols were undertaken on 165 subjects with M. perstans infection and their effects on microfilariae burden were evaluated. Diethylcarbamazine (DEC) was able to reduce microfilariae density in the majority of cases, but it seldom eliminated infection after a single treatment. Mebendazole appeared to be more active than DEC in eliminating the infection, with a comparable rate of overall responses. Ivermectin and praziquantel showed no modification of microfilariae concentration. Thiabendazole showed a small but significant activity against the infection. Combination treatments (DEC plus mebendazole) resulted in a significantly higher activity than the single drugs.

  7. Levothyroxine treatment in pregnancy: indications, efficacy, and therapeutic regimen.

    Science.gov (United States)

    Klubo-Gwiezdzinska, Joanna; Burman, Kenneth D; Van Nostrand, Douglas; Wartofsky, Leonard

    2011-01-01

    The prevalence of overt and subclinical hypothyroidism during pregnancy is estimated to be 0.3-0.5% and 2-3%, respectively. Thyroid autoantibodies are found in 5-18% of women in the childbearing age. The aim of this review is to underscore the clinical significance of these findings on the health of both the mother and her offspring. Methods of evaluation of thyroid function tests (TFTs) during pregnancy are described as are the threshold values for the diagnosis of overt and subclinical hypothyroidism or hypothyroxinemia. Anticipated differences in TFTs in iodine-sufficient and iodine-deficient areas are discussed and data are provided on potential complications of hypothyroidism/hypothyroxinemia and autoimmune thyroid disease during pregnancy and adverse effects for the offspring. The beneficial effects of levothyroxine therapy on pregnancy outcomes and offspring development are discussed with a proposed treatment regimen and follow up strategy.

  8. Levothyroxine Treatment in Pregnancy: Indications, Efficacy, and Therapeutic Regimen

    Directory of Open Access Journals (Sweden)

    Joanna Klubo-Gwiezdzinska

    2011-01-01

    Full Text Available The prevalence of overt and subclinical hypothyroidism during pregnancy is estimated to be 0.3–0.5% and 2–3%, respectively. Thyroid autoantibodies are found in 5–18% of women in the childbearing age. The aim of this review is to underscore the clinical significance of these findings on the health of both the mother and her offspring. Methods of evaluation of thyroid function tests (TFTs during pregnancy are described as are the threshold values for the diagnosis of overt and subclinical hypothyroidism or hypothyroxinemia. Anticipated differences in TFTs in iodine-sufficient and iodine-deficient areas are discussed and data are provided on potential complications of hypothyroidism/hypothyroxinemia and autoimmune thyroid disease during pregnancy and adverse effects for the offspring. The beneficial effects of levothyroxine therapy on pregnancy outcomes and offspring development are discussed with a proposed treatment regimen and follow up strategy.

  9. Comparison of antiplatelet regimens in secondary stroke prevention

    DEFF Research Database (Denmark)

    Christiansen, Christine Benn; Pallisgaard, Jannik; Gerds, Thomas Alexander

    2015-01-01

    BACKGROUND: In patients with ischemic stroke of non-cardioembolic origin, acetylsalicylic acid, clopidogrel, or a combination of acetylsalicylic acid and dipyridamole are recommended for the prevention of a recurrent stroke. The purpose of this study was to examine the risk of bleeding or recurrent...... were calculated for each antiplatelet regimen. RESULTS: Among patients discharged after first-time ischemic stroke, 3043 patients were treated with acetylsalicylic acid, 12,295 with a combination of acetylsalicylic acid and dipyridamole, and 3885 with clopidogrel. Adjusted HRs for clopidogrel versus...... the combination of acetylsalicylic acid and dipyridamole were 1.02 (95% confidence interval [CI]: 0.89-1.17) for ischemic stroke and 1.06 (95% CI: 0.83-1.35) for bleeding. Adjusted HRs for acetylsalicylic acid versus the combination of acetylsalicylic acid and dipyridamole were 1.48 (95% CI: 1.31-1.67) for stroke...

  10. Critical Jostling

    Directory of Open Access Journals (Sweden)

    Pippin Barr

    2016-11-01

    Full Text Available Games can serve a critical function in many different ways, from serious games about real world subjects to self-reflexive commentaries on the nature of games themselves. In this essay we discuss critical possibilities stemming from the area of critical design, and more specifically Carl DiSalvo’s adversarial design and its concept of reconfiguring the remainder. To illustrate such an approach, we present the design and outcomes of two games, Jostle Bastard and Jostle Parent. We show how the games specifically engage with two previous games, Hotline Miami and Octodad: Dadliest Catch, reconfiguring elements of those games to create interactive critical experiences and extensions of the source material. Through the presentation of specific design concerns and decisions, we provide a grounded illustration of a particular critical function of videogames and hope to highlight this form as another valuable approach in the larger area of videogame criticism.

  11. Breast Cancer Screening in an Era of Personalized Regimens

    Science.gov (United States)

    Onega, Tracy; Beaber, Elisabeth F.; Sprague, Brian L.; Barlow, William E.; Haas, Jennifer S.; Tosteson, Anna N.A.; Schnall, Mitchell D.; Armstrong, Katrina; Schapira, Marilyn M.; Geller, Berta; Weaver, Donald L.; Conant, Emily F.

    2014-01-01

    Breast cancer screening holds a prominent place in public health, health care delivery, policy, and women’s health care decisions. Several factors are driving shifts in how population-based breast cancer screening is approached, including advanced imaging technologies, health system performance measures, health care reform, concern for “overdiagnosis,” and improved understanding of risk. Maximizing benefits while minimizing the harms of screening requires moving from a “1-size-fits-all” guideline paradigm to more personalized strategies. A refined conceptual model for breast cancer screening is needed to align women’s risks and preferences with screening regimens. A conceptual model of personalized breast cancer screening is presented herein that emphasizes key domains and transitions throughout the screening process, as well as multilevel perspectives. The key domains of screening awareness, detection, diagnosis, and treatment and survivorship are conceptualized to function at the level of the patient, provider, facility, health care system, and population/policy arena. Personalized breast cancer screening can be assessed across these domains with both process and outcome measures. Identifying, evaluating, and monitoring process measures in screening is a focus of a National Cancer Institute initiative entitled PROSPR (Population-based Research Optimizing Screening through Personalized Regimens), which will provide generalizable evidence for a risk-based model of breast cancer screening, The model presented builds on prior breast cancer screening models and may serve to identify new measures to optimize benefits-to-harms tradeoffs in population-based screening, which is a timely goal in the era of health care reform. PMID:24830599

  12. Criticality Model

    Energy Technology Data Exchange (ETDEWEB)

    A. Alsaed

    2004-09-14

    The ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2003) presents the methodology for evaluating potential criticality situations in the monitored geologic repository. As stated in the referenced Topical Report, the detailed methodology for performing the disposal criticality analyses will be documented in model reports. Many of the models developed in support of the Topical Report differ from the definition of models as given in the Office of Civilian Radioactive Waste Management procedure AP-SIII.10Q, ''Models'', in that they are procedural, rather than mathematical. These model reports document the detailed methodology necessary to implement the approach presented in the Disposal Criticality Analysis Methodology Topical Report and provide calculations utilizing the methodology. Thus, the governing procedure for this type of report is AP-3.12Q, ''Design Calculations and Analyses''. The ''Criticality Model'' is of this latter type, providing a process evaluating the criticality potential of in-package and external configurations. The purpose of this analysis is to layout the process for calculating the criticality potential for various in-package and external configurations and to calculate lower-bound tolerance limit (LBTL) values and determine range of applicability (ROA) parameters. The LBTL calculations and the ROA determinations are performed using selected benchmark experiments that are applicable to various waste forms and various in-package and external configurations. The waste forms considered in this calculation are pressurized water reactor (PWR), boiling water reactor (BWR), Fast Flux Test Facility (FFTF), Training Research Isotope General Atomic (TRIGA), Enrico Fermi, Shippingport pressurized water reactor, Shippingport light water breeder reactor (LWBR), N-Reactor, Melt and Dilute, and Fort Saint Vrain Reactor spent nuclear fuel (SNF). The scope of

  13. THE WORK SIMULATION OF FLOW RATE FOR CARRIAGES' REPAIR AS A MULTIPHASE, MULTIPLEX AND MULTIDISCIPLINARY SYSTEM OF MASS SERVICE

    Directory of Open Access Journals (Sweden)

    V. V. Myamlin

    2011-04-01

    Full Text Available The algorithm of computer simulation of the flexible flow for repair of cars as a multiphase polychannel manyobject queuing system is presented. The basic operators of the model are given and their work is described.

  14. Role of multiphasic multi-detector computed tomography (MDCT in the diagnosis and staging of solid neoplastic renal masses

    Directory of Open Access Journals (Sweden)

    Manal H. Wahba

    2015-03-01

    Conclusion: Multiphase multislice computed tomography combined with CT angiography and CT urography have a major role in solid renal neoplastic masses’ diagnosis, characterization and differentiating benign and malignant tumors.

  15. Morphology Evolution on the Fracture Surface and Fracture Mechanisms of Multiphase Nanostructured ZrCu-Base Alloys

    Directory of Open Access Journals (Sweden)

    Feng Qiu

    2017-03-01

    Full Text Available A multiphase nanostructured ZrCu-base bulk alloy which showed a unique microstructure consisting of sub-micrometer scale Zr2Cu solid solution, nano-sized twinned plate-like ZrCu martensite (ZrCu (M, and retained ZrCu (B2 austenite was fabricated by copper mold casting. The observation of periodic morphology evolution on the fracture surface of the multiphase nanostructured ZrCu-base alloys has been reported, which suggested a fluctuant local stress intensity along the crack propagation. It is necessary to investigate the compressive deformation behavior and the fracture mechanism of the multiphase alloy and the relation to the unique microstructures. The results obtained in this study provide a better understanding of the deformation and fracture mechanisms of multiphase hybrid nanostructured ZrCu-based alloys and give guidance on how to improve the ductility/toughness of bulk ZrCu-based alloys.

  16. An Investigation on the Microstructure of Multi-phase Composite Coatings Synthesized by Plasma Spraying Self-reaction Composite Powders

    Institute of Scientific and Technical Information of China (English)

    DONGYan-chun; YANDian-ran; HeJi-ning; LiXiang-zhi; ZHANGJian-xin; NIUEr-wu

    2004-01-01

    Multi-phase self-reacLion composite (denoted as MPc) coatings containing ceramic and metal multi-phases were fabricated by plasma spraying Fe2O3-Al composite powders. This technology successfully combines self-propagating high-temperature synthesis with plasma spraying. The morphology of the composite powders was examined by scanning electron microscope (SEM). The phase composition and microstructure of the composite coating are studied.

  17. An Investigation on the Microstructure of Multi-phase Composite Coatings Synthesized by Plasma Spraying Self-reaction Composite Powders

    Institute of Scientific and Technical Information of China (English)

    DONG Yan-chun; YAN Dian-ran; HE Ji-ning; LI Xiang-zhi; ZHANG Jian-xin; NIU Er-wu

    2004-01-01

    Multi-phase self-reaction composite (denoted as MPc) coatings containing ceramic and metal multi-phases were fabricated by plasma spraying Fe2O3-Al composite powders. This technology successfully combines self-propagating high-temperature synthesis with plasma spraying. The morphology of the composite powders was examined by scanning electron microscope (SEM). The phase composition and microstructure of the composite coating are studied.

  18. The Relationship between Cognitive Appraisal and Adherence to Medical Regimens in Type 2 Diabetic Patients

    Directory of Open Access Journals (Sweden)

    Shahnaz Ahrari

    2014-12-01

    Full Text Available Introduction: Non-adherence to medical regimen has remained a challenge to the medical profession as well as to social sciences. To achieve positive results, the factors negatively impacting patient adherence to medical regimens (i.e., diet, drug and exercise regimen must be scrutinized in detail. The objective of this research was to explore the relationship between cognitive appraisal and adherence to medical regimens in type 2 diabetic patients. Methods: In this correlational study, 218 type 2 diabetes patients receiving treatment at the Diabetes Clinic affiliated with Gonabad University of Medical Sciences were selected through non-probability (convenience sampling from April 2012 to May 2013. Two valid and reliable questionnaires of cognitive appraisal and adherence to medical regimens were completed by each patient. The data were analyzed using SPSS ver 13. Results: A relationship was observed between perceived cognitive and adherence to some aspects of medical regimen. Also direct relationship was observedbetween perceived cognitive in form challenge and adherence of diet in patients with diabetes. There was no statistically significant relationship between aspects of cognitive appraisal and adherence to the drug regimen. Conclusion: The results suggest that interventions undertaken to improve adherence to medical regimen, particularly to drug regimen in patients with type 2 diabetes, should be focused on enriching cognitive appraisal. Nurses need to help patients perceive diabetes as less of a threat and in fact should empower them, so as to look upon it as more of a challenge.

  19. Therapeutic Response In Mycetoma â€" A Study Of Different Regimens

    Directory of Open Access Journals (Sweden)

    Kaliswaran A V

    2003-01-01

    Full Text Available Treatment of mycetoma is always considered a challenge to the dermatologists. Hence this study was undertaken to determine the efficacy of various therapeutic regimens in actinomycotic and eumycotic mycetoma. A total of 25 patients including 18 cases of actinomycotic mycetoma and 7 cases of eumycotic mycetoma was included. Combinations of trimethoprim-sulfamethoxazole (TS with rifampicin (regimen-3, and TS monotherapy (regimen-4 were used in 9,2,1 and 6 patients with actinomycotic mycetoma respectively. Ketoconazole (regimen-A and itraconazole (regimen-B were used in patients with eumycotic mycetoma along with surgical excision (in amenable cases. Remission was observed in 10 cases of actinomycotic mycetoma (eight with Welsh regimen and one case of eumycetoma who was subjected to surgical excision followed by oral ketoconazole. Improvement was seen in 2 cases of actinomycetoma treated one each with Welsh regimen and regimen4: in 2 cases of eumycetoma treated with ketoconazole in one and itraconazole in the other. No significant adverse effect was noted in the study except ototoxicity and reaction to streptomycin in one patient. In general, therapeutic outcome was excellent in patients with actinomycotic mycetoma particularly with Welsh regimen, whereas the response to medical therapy in eumycetoma is not satisfactory. Complete surgical excision followed by antifungal therapy at an early stage for eumycotic mycetoma is perhaps the best possible therapeutic modality in the present scenario.

  20. Critical Muralism

    Science.gov (United States)

    Rosette, Arturo

    2009-01-01

    This study focuses on the development and practices of Critical Muralists--community-educator-artist-leader-activists--and situates these specifically in relation to the Mexican mural tradition of los Tres Grandes and in relation to the history of public art more generally. The study examines how Critical Muralists address artistic and…

  1. A rational quantitative approach to determine the best dosing regimen for a target therapeutic effect: a unified formalism for antibiotic evaluation.

    Science.gov (United States)

    Li, Jun; Nekka, Fahima

    2013-02-21

    The determination of an optimal dosing regimen is a critical step to enhance the drug efficacy and avoid toxicity. Rational dosing recommendations based on mathematical considerations are increasingly being adopted in the process of drug development and use. In this paper, we propose a quantitative approach to evaluate the efficacy of antibiotic agents. By integrating both pharmacokinetic (PK) and pharmacodynamic (PD) information, this approach gives rise to a unified formalism able to measure the cause-effect of dosing regimens. This new pharmaco-metric allows to cover a whole range of antibiotics, including the two well known concentration and time dependent classes, through the introduction of the Hill-dependency concept. As a direct fallout, our formalism opens a new path toward the bioequivalence evaluation in terms of PK and PD, which associates the in vivo drug concentration and the in vitro drug effect. Using this new approach, we succeeded to reveal unexpected, but relevant behaviors of drug performance when different drug regimens and drug classes are considered. Of particular notice, we found that the doses required to reach the same therapeutic effect, when scheduled differently, exhibit completely different tendencies for concentration and time dependent drugs. Moreover, we theoretically confirmed the previous experimental results of the superiority of the once daily regimen of aminoglycosides. The proposed methodology is appealing for its computational features and can easily be applicable to design fair clinical protocols or rationalize prescription decisions.

  2. Investigation on Reaction Synthesis of Sialon Multiphase Refractory from Clay and Additive TiO2

    Institute of Scientific and Technical Information of China (English)

    XULihua; QIANYangbo; 等

    2001-01-01

    Sialon multiphase composites containting titanium-carbon or titanium-nitrogen have been synthesized from clay nd additive titania through different sintering processes,The experimental results indicated that there was a great change of crystal phase in the similar-composition specimens singtering in air ,nitrogen and bedding protecive poder respectively,determined by XRD analysis,The subsequent evidences were also supplied by SEM.The improvement in mehanical properties of multiphase refracto-ries was observed as the amount of titania changing from 0 to 16%,The main causes maybe come from the excellent properties of high hardness and in-situ strengthening effects of the in-situ formed secondary phase,TiC or TiN.

  3. Smoothed dissipative particle dynamics model for mesoscopic multiphase flows in the presence of thermal fluctuations

    Science.gov (United States)

    Lei, Huan; Baker, Nathan A.; Wu, Lei; Schenter, Gregory K.; Mundy, Christopher J.; Tartakovsky, Alexandre M.

    2016-08-01

    Thermal fluctuations cause perturbations of fluid-fluid interfaces and highly nonlinear hydrodynamics in multiphase flows. In this work, we develop a multiphase smoothed dissipative particle dynamics (SDPD) model. This model accounts for both bulk hydrodynamics and interfacial fluctuations. Interfacial surface tension is modeled by imposing a pairwise force between SDPD particles. We show that the relationship between the model parameters and surface tension, previously derived under the assumption of zero thermal fluctuation, is accurate for fluid systems at low temperature but overestimates the surface tension for intermediate and large thermal fluctuations. To analyze the effect of thermal fluctuations on surface tension, we construct a coarse-grained Euler lattice model based on the mean field theory and derive a semianalytical formula to directly relate the surface tension to model parameters for a wide range of temperatures and model resolutions. We demonstrate that the present method correctly models dynamic processes, such as bubble coalescence and capillary spectra across the interface.

  4. Online Slug Detection in Multi-phase Transportation Pipelines Using Electrical Tomography

    DEFF Research Database (Denmark)

    Pedersen, Simon; Mai, Christian; Hansen, Leif

    2015-01-01

    Slugging flow in offshore oil & gas multi-phase transportation pipelines cause big challenges as the flow regime induces flow and pressure oscillations in the multi-phase pipelines. The negative impacts of the most severe slugs are significant and thus the elimination of slugging flow....... Based on the results the study concludes that the ERT is able to detect the slug very well when the oil and water is well mixed. Furthermore the traditional pressure transmitters have the limitation that pressure variations can be caused by other operating conditions than slug, such as change...... in the back pressure from control valves. The biggest limitation using ERT is the lack of ability to distinguish between gas and oil, and thus the ERT can only be used as an effective slug detect measurement when the oil-to-water ratio is low....

  5. Smoothed dissipative particle dynamics model for mesoscopic multiphase flows in the presence of thermal fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Huan; Baker, Nathan A.; Wu, Lei; Schenter, Gregory K.; Mundy, Christopher J.; Tartakovsky, Alexandre M.

    2016-08-05

    Thermal fluctuations cause perturbations of fluid-fluid interfaces and highly nonlinear hydrodynamics in multiphase flows. In this work, we develop a novel multiphase smoothed dissipative particle dynamics model. This model accounts for both bulk hydrodynamics and interfacial fluctuations. Interfacial surface tension is modeled by imposing a pairwise force between SDPD particles. We show that the relationship between the model parameters and surface tension, previously derived under the assumption of zero thermal fluctuation, is accurate for fluid systems at low temperature but overestimates the surface tension for intermediate and large thermal fluctuations. To analyze the effect of thermal fluctuations on surface tension, we construct a coarse-grained Euler lattice model based on the mean field theory and derive a semi-analytical formula to directly relate the surface tension to model parameters for a wide range of temperatures and model resolutions. We demonstrate that the present method correctly models the dynamic processes, such as bubble coalescence and capillary spectra across the interface.

  6. Speed-sensorless control strategy for multi-phase induction generator in wind energy conversion systems

    Directory of Open Access Journals (Sweden)

    Dumnić Boris P.

    2016-01-01

    Full Text Available Renewable energy sources, especially wind energy conversion systems (WECS, exhibit constant growth. Increase in power and installed capacity led to advances in WECS topologies. Multi-phase approach presents a new development direction, with several key advantages over three-phase systems. Paired with a sensorless control strategy, multi-phase machines are expected to take primacy over standard solutions. This paper presents speed sensorless vector control of an asymmetrical six-phase induction generator based on a model reference adaptive system (MRAS. Suggested topology and developed control algorithm show that sensorless control can yield appropriate dynamic characteristics for the use in WECS with increase in reliability and robustness. [Projekat Ministarstva nauke Republike Srbije, br. III 042004: Smart Electricity Distribution Grids Based on Distribution Management System and Distributed Generation

  7. Fluctuation-induced dynamics of multiphase liquid jets with ultra-low interfacial tension

    CERN Document Server

    Sauret, Alban; Shum, Ho Cheung

    2013-01-01

    Control of fluid dynamics at the micrometer scale is essential to emulsion science and materials design, which is ubiquitous in everyday life and is frequently encountered in industrial applications. Most studies on multiphase flow focus on oil-water systems with substantial interfacial tension. Advances in microfluidics have enabled the study of multiphase flow with more complex dynamics. Here, we show that the evolution of the interface in a jet surrounded by a co-flowing continuous phase with an ultra-low interfacial tension presents new opportunities to the control of flow morphologies. The introduction of a harmonic perturbation to the dispersed phase leads to the formation of interfaces with unique shapes. The periodic structures can be tuned by controlling the fluid flow rates and the input perturbation; this demonstrates the importance of the inertial effects in flow control at ultra-low interfacial tension. Our work provides new insights into microfluidic flows at ultra-low interfacial tension and th...

  8. Origin of resistivity anomaly in p-type leads chalcogenide multiphase compounds

    Energy Technology Data Exchange (ETDEWEB)

    Aminorroaya Yamini, Sima, E-mail: sima@uow.edu.au, E-mail: jsnyder@caltech.edu; Dou, Shi Xue [Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); Mitchell, David R. G. [Electron Microscopy Centre (EMC), Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); Wang, Heng [Materials Science, California Institute of Technology, Pasadena, CA 91125 (United States); Gibbs, Zachary M. [Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 (United States); Pei, Yanzhong [School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804 (China); Snyder, G. Jeffrey, E-mail: sima@uow.edu.au, E-mail: jsnyder@caltech.edu [Electron Microscopy Centre (EMC), Australian Institute for Innovative Materials (AIIM), Innovation Campus, University of Wollongong, NSW 2500 (Australia); ITMO University, Saint Petersburg (Russian Federation)

    2015-05-15

    The electrical resistivity curves for binary phase compounds of p-type lead chalcogenide (PbTe){sub (0.9−x)}(PbSe){sub 0.1}(PbS){sub x,} (x = 0.15, 0.2, 0.25), which contain PbS-rich secondary phases, show different behaviour on heating and cooling between 500-700 K. This is contrast to single phase compounds which exhibit similar behaviour on heating and cooling. We correlate these anomalies in the electrical resistivities of multiphase compounds to the variation in phase composition at high temperatures. The inhomogeneous distribution of dopants between the matrix and secondary phase is found to be crucial in the electronic transport properties of the multiphase compounds. These results can lead to further advances in designing composite Pb-chalcogenides with high thermoelectric performance.

  9. Nonequilibrium Physics and Phase-Field Modeling of Multiphase Flow in Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Juanes, Ruben [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2016-09-01

    The overarching goal of this project was to develop a new continuum theory of multiphase flow in porous media. The theory follows a phase-field modeling approach, and therefore has a sound thermodynamical basis. It is a phenomenological theory in the sense that its formulation is driven by macroscopic phenomena, such as viscous instabilities during multifluid displacement. The research agenda was organized around a set of hypothesis on hitherto unexplained behavior of multiphase flow. All these hypothesis are nontrivial, and testable. Indeed, a central aspect of the project was testing each hypothesis by means of carefully-designed laboratory experiments, therefore probing the validity of the proposed theory. The proposed research places an emphasis on the fundamentals of flow physics, but is motivated by important energy-driven applications in earth sciences, as well as microfluidic technology.

  10. A Fractional-Flow Based Compressible Multiphase Flow Model with Newly Proposed Constitutive Retentions

    Science.gov (United States)

    Tsai, C.; Yeh, G.

    2011-12-01

    In this investigation, newly proposed constitutive retentions are implemented to a fractional-flow based compressible multiphase-phase flow model. With the new model, a compressible three-phase (water, non-aqueous phase liquid (NAPL) and air) flow problem is simulated. In fractional-flow approaches, the three mass balance equations written in terms of three phase pressures are transformed to those in terms of the total pressure, saturation of water, and saturation of total liquid. These three governing equations are discretized with the Galerkin finite element method (FEM). The resulted matrix equation is solved with Bi-CGSTAB. Several numerical experiments are presented to examine the accuracy and robustness of the proposed model. The results show the presented fractional-flow based multiphase flow model is feasible and yields physically realistic solutions for compressible three-phase flow problems in porous media.

  11. Effect of forward looking sites on a multi-phase lattice hydrodynamic model

    Science.gov (United States)

    Redhu, Poonam; Gupta, Arvind Kumar

    2016-03-01

    A new multi-phase lattice hydrodynamic traffic flow model is proposed by considering the effect of multi-forward looking sites on a unidirectional highway. We examined the qualitative properties of proposed model through linear as well as nonlinear stability analysis. It is shown that the multi-anticipation effect can significantly enlarge the stability region on the phase diagram and exhibit three-phase traffic flow. It is also observed that the multi-forward looking sites have prominent influence on traffic flow when driver senses the relative flux of leading vehicles. Theoretical findings are verified using numerical simulation which confirms that the traffic jam is suppressed efficiently by considering the information of leading vehicles in unidirectional multi-phase traffic flow.

  12. Optical diagnostics for turbulent and multiphase flows: Particle image velocimetry and photorefractive optics

    Energy Technology Data Exchange (ETDEWEB)

    O`Hern, T.J.; Torczynski, J.R.; Shagam, R.N.; Blanchat, T.K.; Chu, T.Y.; Tassin-Leger, A.L.; Henderson, J.A.

    1997-01-01

    This report summarizes the work performed under the Sandia Laboratory Directed Research and Development (LDRD) project ``Optical Diagnostics for Turbulent and Multiphase Flows.`` Advanced optical diagnostics have been investigated and developed for flow field measurements, including capabilities for measurement in turbulent, multiphase, and heated flows. Particle Image Velocimetry (PIV) includes several techniques for measurement of instantaneous flow field velocities and associated turbulence quantities. Nonlinear photorefractive optical materials have been investigated for the possibility of measuring turbulence quantities (turbulent spectrum) more directly. The two-dimensional PIV techniques developed under this LDRD were shown to work well, and were compared with more traditional laser Doppler velocimetry (LDV). Three-dimensional PIV techniques were developed and tested, but due to several experimental difficulties were not as successful. The photorefractive techniques were tested, and both potential capabilities and possible problem areas were elucidated.

  13. Popularization of Multiphase Transportation Promotes the Technical Progress in Oil/Gas Gathering and Transportation

    Institute of Scientific and Technical Information of China (English)

    Li Jianmin; Wang Xinlan

    1997-01-01

    @@ At present, the technique of combining multiphase and single phase transportation is commonly adopted in the oil & gas gathering and transportation system of domestic onshore oilfields. This way of transportation not only meets the need of oilfield development and production but also facilitates the management. It is worth improving and popularizing for the onshore oilfields with good material and ground conditions. However, with the enlargement of the oil & gas prospecting and developing areas, if this technique is still in use, the economic benefit of oilfield development would be affected directly. If the multiphase transportation technique is adopted and the oil and gas are pumped together to the gathering station for treatment, obvious economic benefit can be achieved.

  14. LDRD final report: Physical simulation of nonisothermal multiphase multicomponent flow in porous media

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, M.J.; Hopkins, P.L.; Shadid, J.N.

    1997-07-01

    This document reports on the accomplishments of a laboratory-directed research and development (LDRD) project whose objective was to initiate a research program for developing a fundamental understanding of multiphase multicomponent subsurface transport in heterogeneous porous media and to develop parallel processing computational tools for numerical simulation of such problems. The main achievement of this project was the successful development of a general-purpose, unstructured grid, multiphase thermal simulator for subsurface transport in heterogeneous porous media implemented for use on massively parallel (MP) computers via message-passing and domain decomposition techniques. The numerical platform provides an excellent base for new and continuing project development in areas of current interest to SNL and the DOE complex including, subsurface nuclear waste disposal and cleanup, groundwater availability and contamination studies, fuel-spill transport for accident analysis, and DNAPL transport and remediation.

  15. Lattice Boltzmann methods for multiphase flow and phase-change heat transfer

    CERN Document Server

    Li, Qing; Kang, Q J; He, Y L; Chen, Q; Liu, Q

    2016-01-01

    Over the past few decades, tremendous progress has been made in the development of particle-based discrete simulation methods versus the conventional continuum-based methods. In particular, the lattice Boltzmann (LB) method has evolved from a theoretical novelty to a ubiquitous, versatile and powerful computational methodology for both fundamental research and engineering applications. It is a kinetic-based mesoscopic approach that bridges the microscales and macroscales, which offers distinctive advantages in simulation fidelity and computational efficiency. Applications of the LB method have been found in a wide range of disciplines including physics, chemistry, materials, biomedicine and various branches of engineering. The present work provides a comprehensive review of the LB method for thermofluids and energy applications, focusing on multiphase flows, thermal flows and thermal multiphase flows with phase change. The review first covers the theoretical framework of the LB method, revealing the existing ...

  16. Laboratory setup and results of experiments on two-dimensional multiphase flow in porous media

    Energy Technology Data Exchange (ETDEWEB)

    McBride, J.F. (ed.) (Pacific Northwest Lab., Richland, WA (USA)); Graham, D.N. (ed.); Schiegg, H.O. (SIMULTEC Ltd., Meilen/Zurich (Switzerland))

    1990-10-01

    In the event of an accidental release into earth's subsurface of an immiscible organic liquid, such as a petroleum hydrocarbon or chlorinated organic solvent, the spatial and temporal distribution of the organic liquid is of great interest when considering efforts to prevent groundwater contamination or restore contaminated groundwater. An accurate prediction of immiscible organic liquid migration requires the incorporation of relevant physical principles in models of multiphase flow in porous media; these physical principles must be determined from physical experiments. This report presents a series of such experiments performed during the 1970s at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland. The experiments were designed to study the transient, two-dimensional displacement of three immiscible fluids in a porous medium. This experimental study appears to be the most detailed published to date. The data obtained from these experiments are suitable for the validation and test calibration of multiphase flow codes. 73 refs., 140 figs.

  17. Simulation of Subsurface Multiphase Contaminant Extraction Using a Bioslurping Well Model

    Energy Technology Data Exchange (ETDEWEB)

    Matos de Souza, Michelle; Oostrom, Mart; White, Mark D.; Cardoso da Silva, Gerson; Barbosa, Maria Claudia

    2016-07-12

    Subsurface simulation of multiphase extraction from wells is notoriously difficult. Explicit representation of well geometry requires small grid resolution, potentially leading to large computational demands. To reduce the problem dimensionality, multiphase extraction is mostly modeled using vertically-averaged approaches. In this paper, a multiphase well model approach is presented as an alternative to simplify the application. The well model, a multiphase extension of the classic Peaceman model, has been implemented in the STOMP simulator. The numerical solution approach accounts for local conditions and gradients in the exchange of fluids between the well and the aquifer. Advantages of this well model implementation include the option to simulate the effects of well characteristics and operation. Simulations were conducted investigating the effects of extraction location, applied vacuum pressure, and a number of hydraulic properties. The obtained results were all consistent and logical. A major outcome of the test simulations is that, in contrast with common recommendations to extract from either the gas-NAPL or the NAPL-aqueous phase interface, the optimum extraction location should be in between these two levels. The new model implementation was also used to simulate extraction at a field site in Brazil. The simulation shows a good match with the field data, suggesting that the new STOMP well module may correctly represent oil removal. The field simulations depend on the quality of the site conceptual model, including the porous media and contaminant properties and the boundary and extraction conditions adopted. The new module may potentially be used to design field applications and analyze extraction data.

  18. Multi-phase Combustion and Transport Processes Under the Influence of Acoustic Excitation

    OpenAIRE

    Wegener, Jeffrey Lewis

    2014-01-01

    This experimental study examined the coupling of acoustics with reactive multiphase transport processes and shear flows. The first portion of this dissertation deals with combustion of various liquid fuels when under the influence of externally applied acoustic excitation. For this study, an apparatus at the Energy and Propulsion ResearchLaboratory, UCLA, used a horizontal waveguide to create a standing acoustic wave, wherein burning fuel droplets were positioned near pressure nodes within th...

  19. Efficient computations for multiphase flow problems using coupled lattice Boltzmann-level set methods

    OpenAIRE

    Safi, Seyed Mohammad Amin

    2016-01-01

    Multiphase flow simulations benefit a variety of applications in science and engineering as for example in the dynamics of bubble swarms in heat exchangers and chemical reactors or in the prediction of the effects of droplet or bubble impacts in the design of turbomachinery systems. Despite all the progress in the modern computational fluid dynamics (CFD), such simulations still present formidable challenges both from numerical and computational cost point of view. Emerging as ...

  20. SHS Flame Spraying TiC-TiB2 Multiphase Coatings

    Institute of Scientific and Technical Information of China (English)

    WANG Jian-jiang; DU Xin-kang; LU Da-qin; YE Ming-hui; ZHANG Long

    2004-01-01

    Utilizing SHS Reactive Flame Spraying (RFS) technology, TiC-TiB2-Al2O3 multiphase ceramics coatings were produced on steel substrate. Phase constituents and microstructure of the ceramic coatings were analyzed. The procedure of chemical combustion and structure transformation, reactive mechanism, and solidifying behavior during spaying were emphasized. Reactants which influenced on SHS spraying was discussed. SHS reactive spraying processes were studied.Mechanical properties of the coatings were tested.

  1. SHS Flame Spraying TiC-TiB2 Multiphase Coatings

    Institute of Scientific and Technical Information of China (English)

    WANGJian-jiang; DUXin-kang; LUDa-qin; YEMing-hui; ZHANGLong

    2004-01-01

    Utilizing SHS Reactive Flame Spraying (RFS) technology, TiC-TiB2-Al2O3 multiphase ceramics coatings were produced on steel substrate. Phase constituents and microstructure of the ceramic coatings were analyzed. The procedure of chemical combustion and structure transformation, reactive mechanism, and solidifying behavior during spaying were emphasized. Reactants which influenced on SHS spr-aying was discussed. SHS reactive spraying processes were studied, Mechanical properties of the coatings were tested.

  2. A Multiphase First Order Model for Non-Equilibrium Sand Erosion, Transport and Sedimentation

    CERN Document Server

    Preziosi, Luigi; Bruno, Luca

    2015-01-01

    Three phenomena are involved in sand movement: erosion, wind transport, and sedimentation. This paper presents a comprehensive easy-to-use multiphase model that include all three aspects with a particular attention to situations in which erosion due to wind shear and sedimentation due to gravity are not in equilibrium. The interest is related to the fact that these are the situations leading to a change of profile of the sand bed.

  3. MOLECULAR DESIGN SYNTHESIS AND PROPERTIES OF SIX KINDS OF MULTIPHASE (STYRENE-ETHYLENE OXIDE) COPOLYMERS

    Institute of Scientific and Technical Information of China (English)

    XIE Hongquan; ZHOU Peiguang; SUN Wenbo; XIA Jun; LIU Jin; XIE Dong

    1991-01-01

    @@ Multiphase copolymers of styrene (S) and ethylene oxide (EO) are amphiphilic,because of the hydrophobic and amorphous polystyrene (PS) segments and the hydrophilic and crystalline polyoxyethylene (PEO). They have many uses including polymeric surfactants, electrostatic charge reducers, compatibilizer in polymer blending, phase transfer catalysts or solid polymer electrolytes. These copolymers include different types of block copolymers, graft copolymers and star-shaped block copolymers.

  4. Sharp Interface Algorithm for Large Density Ratio Incompressible Multiphase Magnetohydrodynamic Flows

    Science.gov (United States)

    2013-01-01

    Incompressible MHD solver for Arbitrary Geome- tries) is developed to model the flow of liquid metal with free surfaces in the presence of strong multi...24] C. B. Reed S. Molokov. Review of free-surface mhd experiments and modeling . Technical Report ANL/TD/TM99-08, Argonne National Laboratory, 1999...and the corresponding paralleled implementation for the study of magnetohydrodynamics ( MHD ) of large density ratio, three-dimensional multiphase flows

  5. Empirical rheological law of multiphase rocks: Energy minimizing approach independent of bound theory

    Institute of Scientific and Technical Information of China (English)

    ZANG Shaoxian; JIANG Yan; WEI Rongqiang

    2003-01-01

    Based on energy minimizing approach of bound theory, the influence of the distribution of constituent minerals on rheological property of rocks is discussed. Energy minimizing approach independent of the bound theory is advanced after the constraint condition is improved. The strength of four multiphase rocks is calculated with the new empirical rheological law. Results indicate that the new law has a reasonable physical explanation and fits the experimental data very well.

  6. INVESTIGATION OF MULTIPHASE-REINFORCED Si3N4 COMPOSITE MATERIAL

    Institute of Scientific and Technical Information of China (English)

    曾鸣; 丁博; 郭梦熊

    1995-01-01

    By means of whisker reinforce and paricle dispersion, the routes of property improvement on Si3N4 ceramic material have been studied. The mecihaniacl properties of Siw/Si3N4 and Siw/Si3N4TiC material was compared, which proved that multiphase reinforce had overlap effect. Microstructure of the material was investigated by means of SEM and the mechanisms of SiCw and TiCP reinforces had been disussed.

  7. Case study in Venezuela : performance of multiphase meter in extra heavy oil

    Energy Technology Data Exchange (ETDEWEB)

    Marin, A. [Petroleos de Venezuela SA, Caracas (Venezuela); Bornia, O.; Pinguet, B. [Schlumberger Canada Ltd., Edmonton, AB (Canada)

    2008-10-15

    The performance of a multiphase meter that combines Venturi and multi energy gamma rays was investigated during operation in an extra heavy oil field in Venezuela. The Orocual field in Monagas is one of the most diverse oilfields in Venezuela. It produces gas condensate, light and medium oil and has recently started to produce from a heavy and extra-heavy oil reservoir, with a gravity between 8.6 and 11 API and a viscosity range from 6 Pa.s to more than 20 Pa.s at line conditions. Petroleos de Venezuela SA (PDVSA) is currently using cold production systems in this field. PDVSA attempted to estimate the liquid flow rate using conventional storage tanks but was unable to evaluate the gas production in such an environment of low GOR with emulsion, large amounts of foam and high viscosity. Since the density of heavy oil is close to the density of water, gravity separation cannot be applied. Also, since heavy oil is very viscous, proper separation requires a long retention time, which is not feasible in terms of space or economy. In addition, gas bubbles could not flow freely and remained as a gas phase trapped inside the liquid, resulting in an overestimation of some of the liquid flow rate. In order to measure the field's oil, water and gas flow rates, PDVSA tried several multiphase meters but found that a Venturi and multi energy gamma ray combination was the only solution able to accurately measure multiphase flow in its extra heavy oil. A test demonstrated that, compared to a tank system, the overall uncertainty of the Venturi combination was better than 2 per cent. This extended the operating envelope for PDVSA for using this multiphase metering technology, providing the capability to monitor and optimize in real-time the production in this extra heavy oil field. 15 refs., 10 figs.

  8. Accounting for Surface Concentrations Using a VOF Front Tracking Method in Multiphase Flow

    OpenAIRE

    Martin, David Warren

    2015-01-01

    In this dissertation, we present a numerical method for trackingsurfactants on an interface in multiphase flow, along withapplications of the method to two physical problems. We alsopresent an extension of our method to track charged droplets. Ourmethod combines a traditional volume of fluid (VOF) method withmarker tracking. After describing this method in detail, wepresent a series of tests we used to validate our method. Theapplications we consider are the coalescence of surfactant-ladendro...

  9. Modern multiphase catalysis: new developments in the separation of homogeneous catalysts.

    Science.gov (United States)

    Muldoon, Mark J

    2010-01-14

    Homogeneous catalysts are powerful tools for the synthesis of fine chemicals, pharmaceuticals and materials, however their exploitation on an industrial scale is often held back due to the challenges of separating and recycling the catalyst. This perspective focuses on approaches to multiphase catalysis that have emerged in the last decade, highlighting methods that can address the separation issues and in some cases result in superior catalyst performance and environmental benefits.

  10. A Data Management System for Multi-Phase Case-Control Studies

    OpenAIRE

    Gibeau, Joanne M.; Steinfeldt, Lois C; Stine, Mark J.; Tullis, Katherine V.; Lynch, H. Keith

    1983-01-01

    The design of a computerized system for the management of data in multi-phase epidemiologic case-control studies is described. Typical study phases include case-control selection, abstracting of data from medical records, and interview of study subjects or next of kin. In consultation with project personnel, requirements for the system were established: integration of data from all study phases into one data base, accurate follow-up of subjects through the study, sophisticated data editing ca...

  11. Different antibiotic regimens for treating asymptomatic bacteriuria in pregnancy

    Science.gov (United States)

    Guinto, Valerie T; De Guia, Blanca; Festin, Mario R; Dowswell, Therese

    2014-01-01

    Background Asymptomatic bacteriuria occurs in 5% to 10% of pregnancies and, if left untreated, can lead to serious complications. Objectives To assess which antibiotic is most effective and least harmful as initial treatment for asymptomatic bacteriuria in pregnancy. Search methods We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (March 2010) and reference lists of retrieved studies. Selection criteria Randomized controlled trials comparing two antibiotic regimens for treating asymptomatic bacteriuria. Data collection and analysis Review authors independently screened the studies for inclusion and extracted data. Main results We included five studies involving 1140 women with asymptomatic bacteriuria. We did not perform meta-analysis; each trial examined different antibiotic regimens and so we were not able to pool results. In a study comparing a single dose of fosfomycin trometamol 3 g with a five-day course of cefuroxime, there was no significant difference in persistent infection (risk ratio (RR) 1.36, 95% confidence interval (CI) 0.24 to 7.75), shift to other antibiotics (RR 0.08, 95% CI 0.00 to 1.45), or in allergy or pruritus (RR 2.73, 95% CI 0.11 to 65.24). A comparison of seven-day courses of 400 mg pivmecillinam versus 500 mg ampicillin, both given four times daily, showed no significant difference in persistent infection at two weeks or recurrent infection, but there was an increase in vomiting (RR 4.57, 95% CI 1.40 to 14.90) and women were more likely to stop treatment early with pivmecillinam (RR 8.82, 95% CI 1.16 to 66.95). When cephalexin 1 g versus Miraxid® (pivmecillinam 200 mg and pivampicillin 250 mg) were given twice-daily for three days, there was no significant difference in persistent or recurrent infection. A one- versus seven-day course of nitrofurantoin resulted in more persistent infection with the shorter course (RR 1.76, 95% CI 1.29 to 2.40), but no significant difference in symptomatic infection at two weeks

  12. Frictional Fluid Dynamics and Plug Formation in Multiphase Millifluidic Flow

    Science.gov (United States)

    Dumazer, Guillaume; Sandnes, Bjørnar; Ayaz, Monem; Mâløy, Knut Jørgen; Flekkøy, Eirik Grude

    2016-07-01

    We study experimentally the flow and patterning of a granular suspension displaced by air inside a narrow tube. The invading air-liquid interface accumulates a plug of granular material that clogs the tube due to friction with the confining walls. The gas percolates through the static plug once the gas pressure exceeds the pore capillary entry pressure of the packed grains, and a moving accumulation front is reestablished at the far side of the plug. The process repeats, such that the advancing interface leaves a trail of plugs in its wake. Further, we show that the system undergoes a fluidization transition—and complete evacuation of the granular suspension—when the liquid withdrawal rate increases beyond a critical value. An analytical model of the stability condition for the granular accumulation predicts the flow regime.

  13. A new analytical model for thermal stresses in multi-phase materials and lifetime prediction methods

    Institute of Scientific and Technical Information of China (English)

    Ladislav Ceniga

    2008-01-01

    Based on the fundamental equations of the mechanics of solid continuum, the paper employs an ana-lytical model for determination of elastic thermal stresses in isotropic continuum represented by periodically distributed spherical particles with different distributions in an infinite matrix, imaginarily divided into identical cells with dimen-sions equal to inter-particle distances, containing a central spherical particle with or without a spherical envelope on the particle surface. Consequently, the multi-particle-(envelope)-matrix system, as a model system regarding the analytical modelling, is applicable to four types of multi-phase mate-rials. As functions of the particle volume fraction v, the inter-particle distances d1, d2, d3 along three mutually per-pendicular axes, and the particle and envelope radii, R1 and Re, respectively, the thermal stresses within the cell, are originated during a cooling process as a consequence of the difference in thermal expansion coefficients of phases rep-resented by the matrix, envelope and particle. Analytical-(experimental)-computational lifetime prediction methods for multi-phase materials are proposed, which can be used in engineering with appropriate values of parameters of real multi-phase materials.

  14. Multiphase flow modeling of landslide induced impulse wave by VOF method

    Science.gov (United States)

    Paik, J.; Shin, C.

    2015-12-01

    Numerical simulations of impulse waves induced by landslides are carried out using a multiphase modeling approach. The three-dimensional filtered Navier-Stokes equations are used for reproduces the propagation and interaction of Newtonian water wave and non-Newtonian debris flow along the bottom. A multiphase volume of fluid (VOF) method is employed for tracking of fluid interfaces. The governing equations are solved by a second-order-accurate in space and time, finite volume methods and the no-slip conditions are applied for all solid wall. The turbulent shear stress is calculated the Smagorinsky model and the non-Newtonian behavior of debris flow is computed by the Hershel-Bulkley fluid model. The multiphase flow model is applied to reproduce the laboratory measurements of Fritz (Pure Appl. Geophys., 166, 153, 2009) who experimentally investigated the propagation of impulse wave induced by the 1958 Lituya Bay Landslide. The numerical results shows that the proper treatment of the non-Newtonian behavior of debris flow is essential to reproduce its head speed and shape which control the deformation and propagation of the resulting impulse wave.

  15. Applicability condition of time-temperature superposition principle (TTSP) to a multi-phase system

    Science.gov (United States)

    Nakano, Takato

    2013-08-01

    The applicability condition of the time-temperature superposition principle (TTSP) to a multi-phase system is analytically discussed assuming a mixture law. It was concluded that the TTSP does not hold for a multi-phase system in general but does hold for a multi-component system in which some components have the same temperature dependence and the others have no temperature dependence. On the basis of the results, the application of the TTSP to plant materials such as wood and bamboo was examined using a mixture law and a stretched-exponential function having a characteristic relaxation time τ 0 and a stretching parameter β. Wood can be treated as a multi-phase system consisting of a framework (f) and matrix (m). In this case, it was expected that the TTSP holds for the matrix in the shorter time region t≪ τ 0 f under T T gm , where t and T g is a measurement time and the glass transition temperature, respectively.

  16. Numerical Analysis of Velocity Dispersion in Multi-Phase Fluid-Saturated Porous Rocks

    Science.gov (United States)

    Chen, Xuehua; Zhong, Wenli; Gao, Gang; Zou, Wen; He, Zhenhua

    2017-03-01

    Seismic waves are subject to velocity dispersion when they propagate in fluid-saturated porous media. In this work, we explore the velocity dispersion behavior of P- and SV-waves in multi-phase fluid-saturated porous reservoirs while taking into account the effects of multi-phase pore fluids on the effective viscosities that control the wave-induced fluid flow. The effective viscosities associated with the hydrocarbon saturation of a synthetic sandstone reservoir saturated with different pore fluid mixtures are calculated using the Refutas model. We then analyze the frequency-dependent velocity, dispersion variation rate and characteristic frequency for different fluid saturation cases by employing Chapman's dynamic equivalent-medium theory. The results demonstrate that the hydrocarbon proportions and types in multi-phase mixed pore fluids significantly affect the magnitude and characteristic frequencies of velocity dispersion features for both the P- and S-waves. The dispersion anomalies of SV-waves are in general larger than those of the P-waves. This indicates that the velocity dispersion anomalies of SV-waves are equally sensitive to fluid saturation as the P-waves and should not be neglected. The velocities at lower frequencies (e.g., 10 and 100 Hz) within the seismic frequency range show a more remarkable decrease with increasing hydrocarbon proportion than those at higher frequency (1000 Hz). The numerical examples help to improve the understanding of the frequency-dependent AVO inversion from seismic reflection data.

  17. CFD-DP Modeling of Multiphase Flow in Dense Medium Cyclone

    Directory of Open Access Journals (Sweden)

    Okan Topcu

    2012-03-01

    Full Text Available A numerical study of the gas-liquid-solid multi-phase flow in a hydrocyclone is summarized in this paper. The turbulent flow of the gas and the liquid is modelled using the realizable k-epsilon turbulence model, the interface between the liquid and the air core is modelled using the Eulerian multi-phase model and the simulation of the particle flow described by the dense discrete phase model in which the data of the multi-phase flow are used. Separation efficiency, particle trajectories, split ratios, flow field and pressure drop are the examined flow features. The results show that the flow fields in the hydrocyclones are possible to simulate by realizable k-epsilon model which is a fast solver for turbulent flows. The cut size is achieved between 3 and 15 µm. The air-core development is observed to be a transport effect due to the velocity of surrounding fluid rather than a pressure effect. The approach offers a useful method to observe the flow of a hydrocyclone in relation to design of the system and operational conditions.

  18. Multi-phase extraction of glycoraphanin from broccoli using aminium ionic liquid-based silica.

    Science.gov (United States)

    Tian, Minglei; Bi, Wentao; Row, Kyung Ho

    2013-01-01

    Glucosinolates, a class of phytochemicals found in broccoli, have attracted recent interest due to the potential health benefits associated with their dietary intake. Glucoraphanin, the most common glucosinolate in broccoli can be converted to a known cancer chemopreventive agent. Multi-phase extraction in solid-phase extraction cartridges was developed to simultaneously extract and separate this compound. Multi-phase extraction with functionalised ionic liquid-based silica as a sorbent was used to simultaneously extract and separate glucoraphanin from broccoli. The sorbent and broccoli sample were packed into a single cartridge, and a fixed volume of water was then used to extract and remove the target compound from the sample to the sorbent over 15 repetitions. The sorbent was then washed with n-hexane to remove any interference and the target compound was eluted with water-1% acetic acid (vol.). Under the optimised condition, 0.038 mg/g of glucoraphanin was obtained by multi-phase extraction with 0.2 g of sorbent. The adsorption isotherm allowed investigation of the interactions between the sorbent and target compound and provided evidence for the accuracy of this method. The low deviation error, small amount of solvents required, highly selective separation and stability of the method justify further research. Copyright © 2012 John Wiley & Sons, Ltd.

  19. Reentry trajectory optimization with waypoint and no-fly zone constraints using multiphase convex programming

    Science.gov (United States)

    Zhao, Dang-Jun; Song, Zheng-Yu

    2017-08-01

    This study proposes a multiphase convex programming approach for rapid reentry trajectory generation that satisfies path, waypoint and no-fly zone (NFZ) constraints on Common Aerial Vehicles (CAVs). Because the time when the vehicle reaches the waypoint is unknown, the trajectory of the vehicle is divided into several phases according to the prescribed waypoints, rendering a multiphase optimization problem with free final time. Due to the requirement of rapidity, the minimum flight time of each phase index is preferred over other indices in this research. The sequential linearization is used to approximate the nonlinear dynamics of the vehicle as well as the nonlinear concave path constraints on the heat rate, dynamic pressure, and normal load; meanwhile, the convexification techniques are proposed to relax the concave constraints on control variables. Next, the original multiphase optimization problem is reformulated as a standard second-order convex programming problem. Theoretical analysis is conducted to show that the original problem and the converted problem have the same solution. Numerical results are presented to demonstrate that the proposed approach is efficient and effective.

  20. Multi-phase flow effect on SRM nozzle flow field and thermal protection materials

    Institute of Scientific and Technical Information of China (English)

    SHAFQAT Wahab; XIE Kan; LIU Yu

    2009-01-01

    Multi-phase flow effect generated from the combustion of aluminum based com-posite propellant was performed on the thermal protection material of solid rocket motor (SRM) nozzle. Injection of alumina (Al2O3) particles from 5% to 10% was tried on SRM nozzle flow field to see the influence of multiphase flow on heat transfer computations. A coupled, time resolved CFD (computational fluid dynamics) approach was adopted to solve the conjugate problem of multi-phase fluid flow and heat transfer in the solid rocket motor nozzle. The governing equations are discretized by using the finite volume method. Spalart-Allmaras (S-A) turbulence model was employed. The computation was executed on the dif-ferent models selected for the analysis to validate the temperature variation in the throat in-serts and baking material of SRM nozzle. Comparison for temperatures variations were also carried out at different expansion ratios of nozzle. This paper also characterized the advanced SRM nozzle composites material for their high thermo stability and their high thermo me-chanical capabilities to make it more reliable simpler and lighter.

  1. Numerical Analysis of Velocity Dispersion in Multi-Phase Fluid-Saturated Porous Rocks

    Science.gov (United States)

    Chen, Xuehua; Zhong, Wenli; Gao, Gang; Zou, Wen; He, Zhenhua

    2016-12-01

    Seismic waves are subject to velocity dispersion when they propagate in fluid-saturated porous media. In this work, we explore the velocity dispersion behavior of P- and SV-waves in multi-phase fluid-saturated porous reservoirs while taking into account the effects of multi-phase pore fluids on the effective viscosities that control the wave-induced fluid flow. The effective viscosities associated with the hydrocarbon saturation of a synthetic sandstone reservoir saturated with different pore fluid mixtures are calculated using the Refutas model. We then analyze the frequency-dependent velocity, dispersion variation rate and characteristic frequency for different fluid saturation cases by employing Chapman's dynamic equivalent-medium theory. The results demonstrate that the hydrocarbon proportions and types in multi-phase mixed pore fluids significantly affect the magnitude and characteristic frequencies of velocity dispersion features for both the P- and S-waves. The dispersion anomalies of SV-waves are in general larger than those of the P-waves. This indicates that the velocity dispersion anomalies of SV-waves are equally sensitive to fluid saturation as the P-waves and should not be neglected. The velocities at lower frequencies (e.g., 10 and 100 Hz) within the seismic frequency range show a more remarkable decrease with increasing hydrocarbon proportion than those at higher frequency (1000 Hz). The numerical examples help to improve the understanding of the frequency-dependent AVO inversion from seismic reflection data.

  2. High-Fidelity Generalization Method of Cells for Inelastic Periodic Multiphase Materials

    Science.gov (United States)

    Aboudi, Jacob; Pindera, Marek-Jerzy; Arnold, Steven M.

    2002-01-01

    An extension of a recently-developed linear thermoelastic theory for multiphase periodic materials is presented which admits inelastic behavior of the constituent phases. The extended theory is capable of accurately estimating both the effective inelastic response of a periodic multiphase composite and the local stress and strain fields in the individual phases. The model is presently limited to materials characterized by constituent phases that are continuous in one direction, but arbitrarily distributed within the repeating unit cell which characterizes the material's periodic microstructure. The model's analytical framework is based on the homogenization technique for periodic media, but the method of solution for the local displacement and stress fields borrows concepts previously employed by the authors in constructing the higher-order theory for functionally graded materials, in contrast with the standard finite-element solution method typically used in conjunction with the homogenization technique. The present approach produces a closed-form macroscopic constitutive equation for a periodic multiphase material valid for both uniaxial and multiaxial loading. The model's predictive accuracy in generating both the effective inelastic stress-strain response and the local stress said inelastic strain fields is demonstrated by comparison with the results of an analytical inelastic solution for the axisymmetric and axial shear response of a unidirectional composite based on the concentric cylinder model, and with finite-element results for transverse loading.

  3. A high precision TDC based on a multi-phase clock

    CERN Document Server

    Qi, Zhong; Li, Deyuan; Yang, Lei; Yao, Zeen; Li, Dongcang

    2015-01-01

    The design of a high-precision time-to-digital converter (TDC) based on a multiphase clock implemented using a single field-programmable gate array is discussed in this paper. The TDC can increase the resolution of the measurement by using time interpolation. A phase-locked loop is used to generate four multiphase clocks whose frequencies are the same and whose phases are 0{\\deg}, 45{\\deg}, 90{\\deg}, and 135{\\deg}. In addition, the duty ratios of the four clocks are 50%. By utilizing four multiphase clocks to make up the interpolation clock, one clock period can be divided into eight uniform parts. The resolution of the TDC can be improved to 1/8 of a clock period. Furthermore, we have also designed a discriminator circuit for identifying the start and stop signals. On the basis of this circuit, the TDC can still measure the time interval of two signals when the start and stop signals are uncertain. The experimental results indicate that the time resolution of the TDC can achieve the theoretical value, and th...

  4. A Radiative Transfer Modeling Methodology in Gas-Liquid Multiphase Flow Simulations

    Directory of Open Access Journals (Sweden)

    Gautham Krishnamoorthy

    2014-01-01

    Full Text Available A methodology for performing radiative transfer calculations in computational fluid dynamic simulations of gas-liquid multiphase flows is presented. By considering an externally irradiated bubble column photoreactor as our model system, the bubble scattering coefficients were determined through add-on functions by employing as inputs the bubble volume fractions, number densities, and the fractional contribution of each bubble size to the bubble volume from four different multiphase modeling options. The scattering coefficient profiles resulting from the models were significantly different from one another and aligned closely with their predicted gas-phase volume fraction distributions. The impacts of the multiphase modeling option, initial bubble diameter, and gas flow rates on the radiation distribution patterns within the reactor were also examined. An increase in air inlet velocities resulted in an increase in the fraction of larger sized bubbles and their contribution to the scattering coefficient. However, the initial bubble sizes were found to have the strongest impact on the radiation field.

  5. Factors Controlling the Properties of Multi-Phase Arctic Stratocumulus Clouds

    Science.gov (United States)

    Fridlind, Ann; Ackerman, Andrew; Menon, Surabi

    2005-01-01

    The 2004 Multi-Phase Arctic Cloud Experiment (M-PACE) IOP at the ARM NSA site focused on measuring the properties of autumn transition-season arctic stratus and the environmental conditions controlling them, including concentrations of heterogeneous ice nuclei. Our work aims to use a large-eddy simulation (LES) code with embedded size-resolved aerosol and cloud microphysics to identify factors controlling multi-phase arctic stratus. Our preliminary simulations of autumn transition-season clouds observed during the 1994 Beaufort and Arctic Seas Experiment (BASE) indicated that low concentrations of ice nuclei, which were not measured, may have significantly lowered liquid water content and thereby stabilized cloud evolution. However, cloud drop concentrations appeared to be virtually immune to changes in liquid water content, indicating an active Bergeron process with little effect of collection on drop number concentration. We will compare these results with preliminary simulations from October 8-13 during MPACE. The sensitivity of cloud properties to uncertainty in other factors, such as large-scale forcings and aerosol profiles, will also be investigated. Based on the LES simulations with M-PACE data, preliminary results from the NASA GlSS single-column model (SCM) will be used to examine the sensitivity of predicted cloud properties to changing cloud drop number concentrations for multi-phase arctic clouds. Present parametrizations assumed fixed cloud droplet number concentrations and these will be modified using M-PACE data.

  6. Numerical study of natural convection characteristics of nanofluids in an enclosure using multiphase model

    Science.gov (United States)

    Chen, Yan-Jun; Wang, Ping-Yang; Liu, Zhen-Hua

    2016-11-01

    The natural convective heat transfer and flow characteristics of nanofluids in an enclosure are numerically simulated using the multiphase-flow model and single phase model respectively. The simulated results are compared with the experimental results from the published papers to investigate the applicability of these models for nanofluids from a macro standpoint. The effects of Rayleigh number, Grashof number and volume concentration of nanoparticles on the heat transfer and flow characteristics are investigated and discussed. Comparisons of the horizontal and vertical central dimensionless velocity profiles between nanofluid and water for various Grashof numbers are studied. In addition, both streamline contours and isotherms lines for different volume concentrations of nanofluids are analyzed as well. The study results show that a great deviation exists between the simulated result of the single phase model and the experimental data on the relation of Nusselt number and Rayleigh number, which indicates that the single phase model cannot reflect the heat transfer characteristic of nanofluid. While the simulated results using the multiphase-flow model show a good agreement with the experimental data of nanofluid, which means that the multiphase-flow model is more suitable for the numerical study of nanofluid. For the natural convection, the present study holds the point that using Grashof numbers as the benchmark would be more appropriate to describe the heat transfer characteristics of nanofluid. Moreover, the simulated results demonstrate that adding nanoparticles into the base fluid can enhance both the motion of fluid and convection in the enclosure significantly.

  7. Synthetic Observations of Carbon Lines of Turbulent Flows in Diffuse Multiphase Interstellar Medium

    CERN Document Server

    Yamada, M; Omukai, K; Inutsuka, S

    2006-01-01

    We examine observational characteristics of multi-phase turbulent flows in the diffuse interstellar medium (ISM) using a synthetic radiation field of atomic and molecular lines. We consider the multi-phase ISM which is formed by thermal instability under the irradiation of UV photons with moderate visual extinction $A_V\\sim 1$. Radiation field maps of C$^{+}$, C$^0$, and CO line emissions were generated by calculating the non-local thermodynamic equilibrium (nonLTE) level populations from the results of high resolution hydrodynamic simulations of diffuse ISM models. By analyzing synthetic radiation field of carbon lines of [\\ion{C}{2}] 158 $\\mu$m, [\\ion{C}{1}] $^3P_2-^3P_1$ (809 GHz), $^3P_1-^3P_0$ (492 GHz), and CO rotational transitions, we found a high ratio between the lines of high- and low-excitation energies in the diffuse multi-phase interstellar medium. This shows that simultaneous observations of the lines of warm- and cold-gas tracers will be useful in examining the thermal structure, and hence the...

  8. Designing of Multiphase Fly Ash/MWCNT/PU Composite Sheet Against Electromagnetic Environmental Pollution

    Science.gov (United States)

    Gujral, Parth; Varshney, Swati; Dhawan, S. K.

    2016-06-01

    Fly ash and multiwalled carbon nanotubes (MWCNT) reinforced multiphase polyurethane (PU) composite sheets have been fabricated by using a solution casting technique. Utilization of fly ash was the prime objective in order to reduce environmental pollution and to enhance the shielding properties of PU polymer. Our study proves that fly ash particles with MWCNTs in a PU matrix leads to novel hybrid high performance electromagnetic shielding interference material. Scanning electron microscopy confirms the existence of fly ash particles along with MWCNTs in a PU matrix. This multiphase composite shows total shielding effectiveness of 35.8 dB (>99.99% attenuation) in the Ku-band (12.4-18 GHz) frequency range. This is attributed to high dielectric losses of reinforcement present in the polymers matrix. The Nicolson-Ross-Weir algorithm has been applied to calculate the electromagnetic attributes and dielectric parameters of the PU samples by using scattering parameters ( S 11, S 22, S 12, S 21). The synthesized multiphase composites were further characterized by using x-ray diffraction, Fourier transform infrared spectroscopy, and thermo gravimetric analysis.

  9. Modeling and simulation challenges in Eulerian-Lagrangian computations of multiphase flows

    Science.gov (United States)

    Diggs, Angela; Balachandar, S.

    2017-01-01

    The present work addresses the numerical methods required for particle-gas and particle-particle interactions in Eulerian-Lagrangian simulations of multiphase flow. Local volume fraction as seen by each particle is the quantity of foremost importance in modeling and evaluating such interactions. We consider a general multiphase flow with a distribution of particles inside a fluid flow discretized on an Eulerian grid. Particle volume fraction is needed both as a Lagrangian quantity associated with each particle and also as an Eulerian quantity associated with the flow. In Grid-Based (GB) methods, the volume fraction is first obtained within each cell as an Eulerian quantity and then interpolated to each particle. In Particle-Based (PB) methods, the particle volume fraction is obtained at each particle and then projected onto the Eulerian grid. Traditionally, GB methods are used in multiphase flow, but sub-grid resolution can be obtained through use of PB methods. By evaluating the total error and its components we compare the performance of GB and PB methods. The standard von Neumann error analysis technique has been adapted for rigorous evaluation of rate of convergence. The methods presented can be extended to obtain accurate field representations of other Lagrangian quantities.

  10. Supertoughened renewable PLA reactive multiphase blends system: phase morphology and performance.

    Science.gov (United States)

    Zhang, Kunyu; Nagarajan, Vidhya; Misra, Manjusri; Mohanty, Amar K

    2014-08-13

    Multiphase blends of poly(lactic acid) (PLA), ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) terpolymer, and a series of renewable poly(ether-b-amide) elastomeric copolymer (PEBA) were fabricated through reactive melt blending in an effort to improve the toughness of the PLA. Supertoughened PLA blend showing impact strength of ∼500 J/m with partial break impact behavior was achieved at an optimized blending ratio of 70 wt % PLA, 20 wt % EMA-GMA, and 10 wt % PEBA. Miscibility and thermal behavior of the binary blends PLA/PEBA and PLA/EMA-GMA, and the multiphase blends were also investigated through differential scanning calorimetric (DSC) and dynamic mechanical analysis (DMA). Phase morphology and fracture surface morphology of the blends were studied through scanning electron microscopy (SEM) and atomic force microscopy (AFM) to understand the strong corelation between the morphology and its significant effect on imparting tremendous improvement in toughness. A unique "multiple stacked structure" with partial encapsulation of EMA-GMA and PEBA minor phases was observed for the PLA/EMA-GMA/PEBA (70/20/10) revealing the importance of particular blend composition in enhancing the toughness. Toughening mechanism behind the supertoughened PLA blends have been established by studying the impact fractured surface morphology at different zones of fracture. Synergistic effect of good interfacial adhesion and interfacial cavitations followed by massive shear yielding of the matrix was believed to contribute to the enormous toughening effect observed in these multiphase blends.

  11. Multiphasic on/off pheromone signalling in moths as neural correlates of a search strategy.

    Directory of Open Access Journals (Sweden)

    Dominique Martinez

    Full Text Available Insects and robots searching for odour sources in turbulent plumes face the same problem: the random nature of mixing causes fluctuations and intermittency in perception. Pheromone-tracking male moths appear to deal with discontinuous flows of information by surging upwind, upon sensing a pheromone patch, and casting crosswind, upon losing the plume. Using a combination of neurophysiological recordings, computational modelling and experiments with a cyborg, we propose a neuronal mechanism that promotes a behavioural switch between surge and casting. We show how multiphasic On/Off pheromone-sensitive neurons may guide action selection based on signalling presence or loss of the pheromone. A Hodgkin-Huxley-type neuron model with a small-conductance calcium-activated potassium (SK channel reproduces physiological On/Off responses. Using this model as a command neuron and the antennae of tethered moths as pheromone sensors, we demonstrate the efficiency of multiphasic patterning in driving a robotic searcher toward the source. Taken together, our results suggest that multiphasic On/Off responses may mediate olfactory navigation and that SK channels may account for these responses.

  12. Modeling multiphase, multicomponent flows at the pore scale: Wetting phenomena and non-equilibrium phase behavior

    Science.gov (United States)

    Cueto-Felgueroso, L.; Fu, X.; Juanes, R.

    2016-12-01

    The description of multicomponent flows with complex phase behavior remains an open challenge in pore-scale modeling. Darcy-scale general purpose simulators assume local thermodynamic equilibrium, and perform equation-of-state-based calculations to make phase equilibrium predictions; that is, to determine the phase volume fractions and their compositions from overall component mole fractions. What remains unclear is whether the thermodynamic equilibrium assumption is valid given the flow conditions, complex structure of the pore space and characteristic time scales for flow. Diffuse-interface theories of multiphase flow have recently emerged as promising tools to understand and simulate complex processes involving the simultaneous flow of two or more immiscible fluid phases. The common goal in these approaches is to formulate thermodynamically consistent stress tensors and mesoscale balance laws, including the impact of surface tension on the momentum balance, as well as properly tracking interfacial dynamics and mass transfer. We propose a phase-field model of multiphase, multicomponent flow, which we use to address the following research questions: What is the impact of the wetting conditions at the pore scale on upscaled descriptions of multiphase flow? What is the impact of the displacement dynamics, pore space structure and wetting conditions on the phase behavior of multicomponent mixtures? We finally investigate upscaling procedures to incorporate non-equilibrium phase behavior at the continuum scale.

  13. Multiphasic on/off pheromone signalling in moths as neural correlates of a search strategy.

    Science.gov (United States)

    Martinez, Dominique; Chaffiol, Antoine; Voges, Nicole; Gu, Yuqiao; Anton, Sylvia; Rospars, Jean-Pierre; Lucas, Philippe

    2013-01-01

    Insects and robots searching for odour sources in turbulent plumes face the same problem: the random nature of mixing causes fluctuations and intermittency in perception. Pheromone-tracking male moths appear to deal with discontinuous flows of information by surging upwind, upon sensing a pheromone patch, and casting crosswind, upon losing the plume. Using a combination of neurophysiological recordings, computational modelling and experiments with a cyborg, we propose a neuronal mechanism that promotes a behavioural switch between surge and casting. We show how multiphasic On/Off pheromone-sensitive neurons may guide action selection based on signalling presence or loss of the pheromone. A Hodgkin-Huxley-type neuron model with a small-conductance calcium-activated potassium (SK) channel reproduces physiological On/Off responses. Using this model as a command neuron and the antennae of tethered moths as pheromone sensors, we demonstrate the efficiency of multiphasic patterning in driving a robotic searcher toward the source. Taken together, our results suggest that multiphasic On/Off responses may mediate olfactory navigation and that SK channels may account for these responses.

  14. Experimental and computational analysis of pressure response in a multiphase flow loop

    Science.gov (United States)

    Morshed, Munzarin; Amin, Al; Rahman, Mohammad Azizur; Imtiaz, Syed

    2016-07-01

    The characteristics of multiphase fluid flow in pipes are useful to understand fluid mechanics encountered in the oil and gas industries. In the present day oil and gas exploration is successively inducing subsea operation in the deep sea and arctic condition. During the transport of petroleum products, understanding the fluid dynamics inside the pipe network is important for flow assurance. In this case the information regarding static and dynamic pressure response, pressure loss, optimum flow rate, pipe diameter etc. are the important parameter for flow assurance. The principal aim of this research is to represents computational analysis and experimental analysis of multi-phase (L/G) in a pipe network. This computational study considers a two-phase fluid flow through a horizontal flow loop with at different Reynolds number in order to determine the pressure distribution, frictional pressure loss profiles by volume of fluid (VOF) method. However, numerical simulations are validated with the experimental data. The experiment is conducted in 76.20 mm ID transparent circular pipe using water and air in the flow loop. Static pressure transducers are used to measure local pressure response in multiphase pipeline.

  15. A Simple Control Strategy Using Speedy Transient Response for Multiphase Buck Converter

    Science.gov (United States)

    Sasikala, K.; Ravikumar, D.; Rubini, B.

    2017-03-01

    The high performance of recent originating digital processors requires power supply for transient output, firm voltage regulation and high current. Industry has taken up interleaved multiphase synchronous buck converters for meeting such demands. Application of the voltage mode (ripple) hysteretic strategy to multiphase Voltage Regulator Units (VRU) would help satisfying many of the upcoming digital processors and IC’s powering demands. This arises from the use of the various advantages that can be obtained from this technique. This current division method is known for several benefits it provides: easy accessibility in application to all control methods, with freedom from the prime control technique in voltage regulation loop, absence of any necessity for current reference, better accuracy in current division of equal magnitude at almost every load conditions in standstill and transients. As against this, there are several challenges that involve distribution of multiple control signals, current sharing and sensitivity to noise, high speed comparators, hysteretic band accuracy and stable at large load transients. In addition, application of the current division technique presented was made to a multiphase voltage mode ripple controlled Buck Converter that produced a novel and easy control strategy having minimum output voltage ripples and speedy transient output.

  16. Aggressive regimens for multidrug-resistant tuberculosis decrease all-cause mortality.

    Directory of Open Access Journals (Sweden)

    Carole D Mitnick

    Full Text Available RATIONALE: A better understanding of the composition of optimal treatment regimens for multidrug-resistant tuberculosis (MDR-TB is essential for expanding universal access to effective treatment and for developing new therapies for MDR-TB. Analysis of observational data may inform the definition of an optimized regimen. OBJECTIVES: This study assessed the impact of an aggressive regimen-one containing at least five likely effective drugs, including a fluoroquinolone and injectable-on treatment outcomes in a large MDR-TB patient cohort. METHODS: This was a retrospective cohort study of patients treated in a national outpatient program in Peru between 1999 and 2002. We examined the association between receiving an aggressive regimen and the rate of death. MEASUREMENTS AND MAIN RESULTS: In total, 669 patients were treated with individualized regimens for laboratory-confirmed MDR-TB. Isolates were resistant to a mean of 5.4 (SD 1.7 drugs. Cure or completion was achieved in 66.1% (442 of patients; death occurred in 20.8% (139. Patients who received an aggressive regimen were less likely to die (crude hazard ratio [HR]: 0.62; 95% CI: 0.44,0.89, compared to those who did not receive such a regimen. This association held in analyses adjusted for comorbidities and indicators of severity (adjusted HR: 0.63; 95% CI: 0.43,0.93. CONCLUSIONS: The aggressive regimen is a robust predictor of MDR-TB treatment outcome. TB policy makers and program directors should consider this standard as they design and implement regimens for patients with drug-resistant disease. Furthermore, the aggressive regimen should be considered the standard background regimen when designing randomized trials of treatment for drug-resistant TB.

  17. Aggressive regimens for multidrug-resistant tuberculosis decrease all-cause mortality.

    Science.gov (United States)

    Mitnick, Carole D; Franke, Molly F; Rich, Michael L; Alcantara Viru, Felix A; Appleton, Sasha C; Atwood, Sidney S; Bayona, Jaime N; Bonilla, Cesar A; Chalco, Katiuska; Fraser, Hamish S F; Furin, Jennifer J; Guerra, Dalia; Hurtado, Rocio M; Joseph, Keith; Llaro, Karim; Mestanza, Lorena; Mukherjee, Joia S; Muñoz, Maribel; Palacios, Eda; Sanchez, Epifanio; Seung, Kwonjune J; Shin, Sonya S; Sloutsky, Alexander; Tolman, Arielle W; Becerra, Mercedes C

    2013-01-01

    A better understanding of the composition of optimal treatment regimens for multidrug-resistant tuberculosis (MDR-TB) is essential for expanding universal access to effective treatment and for developing new therapies for MDR-TB. Analysis of observational data may inform the definition of an optimized regimen. This study assessed the impact of an aggressive regimen-one containing at least five likely effective drugs, including a fluoroquinolone and injectable-on treatment outcomes in a large MDR-TB patient cohort. This was a retrospective cohort study of patients treated in a national outpatient program in Peru between 1999 and 2002. We examined the association between receiving an aggressive regimen and the rate of death. In total, 669 patients were treated with individualized regimens for laboratory-confirmed MDR-TB. Isolates were resistant to a mean of 5.4 (SD 1.7) drugs. Cure or completion was achieved in 66.1% (442) of patients; death occurred in 20.8% (139). Patients who received an aggressive regimen were less likely to die (crude hazard ratio [HR]: 0.62; 95% CI: 0.44,0.89), compared to those who did not receive such a regimen. This association held in analyses adjusted for comorbidities and indicators of severity (adjusted HR: 0.63; 95% CI: 0.43,0.93). The aggressive regimen is a robust predictor of MDR-TB treatment outcome. TB policy makers and program directors should consider this standard as they design and implement regimens for patients with drug-resistant disease. Furthermore, the aggressive regimen should be considered the standard background regimen when designing randomized trials of treatment for drug-resistant TB.

  18. Critical proximity

    Directory of Open Access Journals (Sweden)

    Simon, Jane

    2010-01-01

    Full Text Available This essay considers how written language frames visual objects. Drawing on Michel Foucault’s response to Raymond Roussel’s obsessive description, the essay proposes a model of criticism where description might press up against its objects. This critical closeness is then mapped across the conceptual art practice and art criticism of Ian Burn. Burn attends to the differences between seeing and reading, and considers the conditions which frame how we look at images, including how we look at, and through words. The essay goes on to consider Meaghan Morris’s writing on Lynn Silverman’s photographs. Both Morris and Burn offer an alternative to a parasitic model of criticism and enact a patient way of looking across and through visual landscapes.

  19. Critical Proximity

    Directory of Open Access Journals (Sweden)

    Jane Simon

    2010-09-01

    Full Text Available This essay considers how written language frames visual objects. Drawing on Michel Foucault’s response to Raymond Roussel’s obsessive description, the essay proposes a model of criticism where description might press up against its objects. This critical closeness is then mapped across the conceptual art practice and art criticism of Ian Burn. Burn attends to the differences between seeing and reading, and considers the conditions which frame how we look at images, including how we look at, and through words. The essay goes on to consider Meaghan Morris’s writing on Lynn Silverman’s photographs. Both Morris and Burn offer an alternative to a parasitic model of criticism and enact a patient way of looking across and through visual landscapes.

  20. Pharmacist-patient communication about medication regimen adjustment during Ramadan.

    Science.gov (United States)

    Amin, Mohamed E K; Chewning, Betty

    2016-12-01

    During Ramadan, Muslims fast from dawn to sunset while abstaining from food and drink. Although Muslim patients may be aware of their religious exemption from fasting, many patients still choose not to take that exemption and fast. This study examines pharmacists' initiation and timing of communication about medication regimen adjustment (MRA) with patients related to Ramadan. Predictors for initiating this communication with patients were also explored. A probability sample of community pharmacists in Alexandria, Egypt was surveyed. The self-administered instrument covered timing and likelihood of initiating discussion about MRA. Using ordered logistic regression, a model was estimated to predict pharmacists' initiation of the conversation on MRA during Ramadan. Ninety-three percent of the 298 approached pharmacists completed surveys. Only 16% of the pharmacists reported that they themselves usually initiated the conversation on MRA. Pharmacists' initiation of these conversations was associated with pharmacists' perceived importance of MRA on pharmacy revenue odds ratio ((OR) = 1.24, CI = 1.03-1.48). Eighty percent of the responding pharmacists reported the MRA conversation for chronic conditions started either 1-3 days before, or during the first week of Ramadan. These results suggest considerable pharmacist patient communication gaps regarding medication use during Ramadan. It is especially important for pharmacists and other health professionals to initiate communication with Muslim patients early enough to identify how best to help patients transition safely into and out of Ramadan as they fast. © 2016 Royal Pharmaceutical Society.