Effective methods for cash flow analysis.
Sylvestre, J; Urbancic, F R
1994-07-01
This article discusses techniques that healthcare financial managers can use to interpret and evaluate information from the statement of cash flows for more effective financial decision-making. The use of these techniques as a basis for systematically planning and controlling cash flows has the potential to benefit all healthcare organizations.
Adaptive computational methods for SSME internal flow analysis
Oden, J. T.
1986-01-01
Adaptive finite element methods for the analysis of classes of problems in compressible and incompressible flow of interest in SSME (space shuttle main engine) analysis and design are described. The general objective of the adaptive methods is to improve and to quantify the quality of numerical solutions to the governing partial differential equations of fluid dynamics in two-dimensional cases. There are several different families of adaptive schemes that can be used to improve the quality of solutions in complex flow simulations. Among these are: (1) r-methods (node-redistribution or moving mesh methods) in which a fixed number of nodal points is allowed to migrate to points in the mesh where high error is detected; (2) h-methods, in which the mesh size h is automatically refined to reduce local error; and (3) p-methods, in which the local degree p of the finite element approximation is increased to reduce local error. Two of the three basic techniques have been studied in this project: an r-method for steady Euler equations in two dimensions and a p-method for transient, laminar, viscous incompressible flow. Numerical results are presented. A brief introduction to residual methods of a-posterior error estimation is also given and some pertinent conclusions of the study are listed.
Continuous maximum flow segmentation method for nanoparticle interaction analysis.
Marak, L; Tankyevych, O; Talbot, H
2011-10-01
In recent years, tomographic three-dimensional reconstruction approaches using electrons rather than X-rays have become popular. Such images produced with a transmission electron microscope make it possible to image nanometre-scale materials in three-dimensional. However, they are also noisy, limited in contrast and most often have a very poor resolution along the axis of the electron beam. The analysis of images stemming from such modalities, whether fully or semiautomated, is therefore more complicated. In particular, segmentation of objects is difficult. In this paper, we propose to use the continuous maximum flow segmentation method based on a globally optimal minimal surface model. The use of this fully automated segmentation and filtering procedure is illustrated on two different nanoparticle samples and provide comparisons with other classical segmentation methods. The main objectives are the measurement of the attraction rate of polystyrene beads to silica nanoparticle (for the first sample) and interaction of silica nanoparticles with large unilamellar liposomes (for the second sample). We also illustrate how precise measurements such as contact angles can be performed.
CyNC - a method for Real Time Analysis of Systems with Cyclic Data Flows
DEFF Research Database (Denmark)
Schiøler, Henrik; Nielsen, Jens F. Dalsgaard; Larsen, Kim Guldstrand
2005-01-01
The paper addresses a novel method for realtime analysis of systems with cyclic data flows. The presented method is based on Network Calculus principles, where upper and lower flow and service constraint are used to bound data flows and processing resources. In acyclic systems flow constraints may...
Axial and Centrifugal Compressor Mean Line Flow Analysis Method
Veres, Joseph P.
2009-01-01
This paper describes a method to estimate key aerodynamic parameters of single and multistage axial and centrifugal compressors. This mean-line compressor code COMDES provides the capability of sizing single and multistage compressors quickly during the conceptual design process. Based on the compressible fluid flow equations and the Euler equation, the code can estimate rotor inlet and exit blade angles when run in the design mode. The design point rotor efficiency and stator losses are inputs to the code, and are modeled at off design. When run in the off-design analysis mode, it can be used to generate performance maps based on simple models for losses due to rotor incidence and inlet guide vane reset angle. The code can provide an improved understanding of basic aerodynamic parameters such as diffusion factor, loading levels and incidence, when matching multistage compressor blade rows at design and at part-speed operation. Rotor loading levels and relative velocity ratio are correlated to the onset of compressor surge. NASA Stage 37 and the three-stage NASA 74-A axial compressors were analyzed and the results compared to test data. The code has been used to generate the performance map for the NASA 76-B three-stage axial compressor featuring variable geometry. The compressor stages were aerodynamically matched at off-design speeds by adjusting the variable inlet guide vane and variable stator geometry angles to control the rotor diffusion factor and incidence angles.
On-line sample processing methods in flow analysis
DEFF Research Database (Denmark)
Miró, Manuel; Hansen, Elo Harald
2008-01-01
In this chapter, the state of the art of flow injection and related approaches thereof for automation and miniaturization of sample processing regardless of the aggregate state of the sample medium is overviewed. The potential of the various generation of flow injection for implementation of in......-line dilution, derivatization, separation and preconcentration methods encompassing solid reactors, solvent extraction, sorbent extraction, precipitation/coprecipitation, hydride/vapor generation and digestion/leaching protocols as hyphenated to a plethora of detection devices is discussed in detail...
Analysis of Axial Flow Ventilation Fans by Vortex - Method.
Hardin, Richard Anthony
A steady vortex-lattice method is used to solve the lifting surface equation for an axial flow fan. The type of fan studied is designed for industrial and ventilation applications and in thermofluid systems such as cooling towers. The fan blades are thin cambered surfaces manufactured from metal sheets. The numerical approach is inviscid and results in a boundary value problem with viscous effects partially accounted for by application of drag coefficient data. A non-linear wake alignment procedure is used to account for the effects of vorticity shedding in the wake and variation in wake geometry with operating conditions. The wake alignment procedure is semi-free with wake input parameters required for accurate use of the technique. A study of the wake parameters was conducted and gave trends in the variation of their values with flow rate. At "free-air" conditions, flow visualization estimates of these parameters were found to agree with those from the computations. Comparisons are made between the measured and predicted fan performance with and without a surrounding duct. The comparison of the results were especially good at the "free-air" condition using wake parameters determined from flow visualization and an inlet velocity profile measured using hot-wire anemometry. To enable better understanding of basic flow phenomena and to provide data for verification of numerical analyses, a method for measuring unsteady surface pressure on a rotating axial-flow fan blade was devised. Unsteadiness of pressure on the blade surfaces is due to the effects of upstream fan motor supports and other installation features. A pressure transducer and signal amplification circuit were mounted on a circuit board at the rotating hub with signals taken off the rotating shaft through copper disk-mercury slip rings. The pressure difference across the blade was determined and the data were corrected for time lag and distortion caused by the length of tubing. The pressure difference
Discontinuous Galerkin method analysis and applications to compressible flow
Dolejší, Vít
2015-01-01
The subject of the book is the mathematical theory of the discontinuous Galerkin method (DGM), which is a relatively new technique for the numerical solution of partial differential equations. The book is concerned with the DGM developed for elliptic and parabolic equations and its applications to the numerical simulation of compressible flow. It deals with the theoretical as well as practical aspects of the DGM and treats the basic concepts and ideas of the DGM, as well as the latest significant findings and achievements in this area. The main benefit for readers and the book’s uniqueness lie in the fact that it is sufficiently detailed, extensive and mathematically precise, while at the same time providing a comprehensible guide through a wide spectrum of discontinuous Galerkin techniques and a survey of the latest efficient, accurate and robust discontinuous Galerkin schemes for the solution of compressible flow.
CyNC: A method for real time analysis of systems with cyclic data flows
DEFF Research Database (Denmark)
Jessen, Jan Jacob; Schiøler, Henrik; Nielsen, Jens Frederik Dalsgaard
2006-01-01
The paper addresses a novel method for performance analysis of distributed realtime systems with complex, and especially cyclic data flow graphs. The presented method is based on Network Calculus principles, where flow and service constraint functions are used to bound data flows and processing...
Generalized Method of Variational Analysis for 3-D Flow
Institute of Scientific and Technical Information of China (English)
兰伟仁; 黄思训; 项杰
2004-01-01
The generalized method of variational analysis (GMVA) suggested for 2-D wind observations by Huang et al. is extended to 3-D cases. Just as in 2-D cases, the regularization idea is applied. But due to the complexity of the 3-D cases, the vertical vorticity is taken as a stable functional. The results indicate that wind observations can be both variationally optimized and filtered. The efficiency of GMVA is also checked in a numerical test. Finally, 3-D wind observations with random disturbances are manipulated by GMVA after being filtered.
Pierzga, M. J.
1981-01-01
The experimental verification of an inviscid, incompressible through-flow analysis method is presented. The primary component of this method is an axisymmetric streamline curvature technique which is used to compute the hub-to-tip flow field of a given turbomachine. To analyze the flow field in the blade-to-blade plane of the machine, the potential flow solution of an infinite cascade of airfoils is also computed using a source model technique. To verify the accuracy of such an analysis method an extensive experimental verification investigation was conducted using an axial flow research fan. Detailed surveys of the blade-free regions of the machine along with intra-blade surveys using rotating pressure sensing probes and blade surface static pressure taps provide a one-to-one relationship between measured and predicted data. The results of this investigation indicate the ability of this inviscid analysis method to predict the design flow field of the axial flow fan test rotor to within a few percent of the measured values.
Energy Technology Data Exchange (ETDEWEB)
Park, S.R. [Inha University, Inchon (Korea); Kim, Y.J.; Kim, T.W. [Doowon Technical College, Ansung (Korea)
1999-12-01
This paper presents a quasi-three-dimensional calculation method considered a spanwise mixing effect in a diagonal flow impeller. The effect of this spanwise mixing caused by spanwise distribution of blade loading is evaluated by a secondary flow theory. In order to verify the validity of this method, it is applied to the analysis of a diagonal flow fan designed under a vortex type of constant circumferential velocity and that of a free vortex. The comparison of the calculated result with experimental data shows a good agreement except the regions near the casing where the flow field is affected by the tip leakage flow. (author). 18 refs., 10 figs.
Pierzga, M. J.
1980-05-01
To verify the results of a streamline curvature numerical analysis method, an investigation has been conducted in which comparisons are made between analytical and experimental data of an axial flow fan. Using loss model calculations to determine the proper outlet flow deviation angles, the flow field in the hub to tip plane of the turbomachine was calculated. These deviation angle calculations allow the inviscid streamline curvature (SLC) analysis to model a real fluid with viscous losses. The verification of this calculated flow field is the primary objective of the investigation; however, in addition to the hub to tip flow field, the numerical analysis of the blade-to-blade flow field was also investigated in some detail. To verify the accuracy of the numerical results, detailed flow surveys were conducted upstream and downstream of the test rotor of the axial flow fan. To obtain the necessary data to verify the blade-to-blade solution, internal blade row data were also collected. The internal blade row measurements were obtained by using a rotating circumferential traversing mechanism which was designed and implemented during this investigation. Along with these two sets of survey data, the static pressure distributions on the pressure and suction surfaces of the test rotor were also obtained.
STUDY ON SIMULATION METHOD OF AVALANCHE : FLOW ANALYSIS OF AVALANCHE USING PARTICLE METHOD
2015-01-01
In this paper, modeling for the simulation of the avalanche by a particle method is discussed. There are two kinds of the snow avalanches, one is the surface avalanche which shows a smoke-like flow, and another is the total-layer avalanche which shows a flow like Bingham fluid. In the simulation of the surface avalanche, the particle method in consideration of a rotation resistance model is used. The particle method by Bingham fluid is used in the simulation of the total-layer avalanche. At t...
Automation of semen analysis using flow cytometer in comparison with manual methods.
Saleh, Mohamed; Fathy, Amal; El-Akras, Atef I; Eyada, Mostafa M; Younes, Soha; El-Gohary, Ahmed M
2005-01-01
In order to standardize techniques and limit the effect of human factors on the results of analyses of biological fluids, automation seems to be mandatory. In an attempt to automate semen analysis, computer assisted sperm analysis (CASA) system has been developed, however its use is still limited and its practical applications have many criticisms. In a trial to automate semen analysis, this study aimed to evaluate the usefulness of flow cytometer in the detection of some seminal parameters in comparison with the traditional manual methods. Isolated spermatogenic cells and isolated sperms from semen and EDTA blood of volunteers were analyzed by flow cytometer in order to define their respective regions. Ejaculates of 28 male patients were subjected to routine semen analyses, leucocytes detection by peroxidase test and monoclonal antibody CD53 using flow cytometer after preparation of the patients' semen samples for flow cytometeric analysis. A highly significant correlation (r=0.96, p= 0.001) of absolute neutrophils (pus cells) detected by peroxidase versus flow cytometer using CD53 monoclonal antibody. A poor correlation (r=0.39, p=0.035) of sperm counts assessed by manual technique and flow cytometer and a spurious sperm counts of 1.08 million/ml detected by flow cytometery in azoospermic patients. Flow cytometer could be used for the assessment of pus cells in semen but seems to be non reliable for the assessment of sperm count if gating depend on sperm size and granularity alone.
Huang, Huaxiong; Takagi, Shu
2003-08-01
In this paper, we study the convergence property of PHYSALIS when it is applied to incompressible particle flows in two-dimensional space. PHYSALIS is a recently proposed iterative method which computes the solution without imposing the boundary conditions on the particle surfaces directly. Instead, a consistency equation based on the local (near particle) representation of the solution is used as the boundary conditions. One of the important issues needs to be addressed is the convergence properties of the iterative procedure. In this paper, we present the convergence analysis using Laplace and biharmonic equations as two model problems. It is shown that convergence of the method can be achieved but the rate of convergence depends on the relative locations of the cages. The results are directly related to potential and Stokes flows. However, they are also relevant to Navier-Stokes flows, heat conduction in composite media, and other problems.
Quick Analysis Method for Estimating Debris Flow Prone Area Caused by Overflow from Landslide dam
Shimizu, T.; Uchida, T.; Yamakoshi, T.; Yoshino, K.; Kisa, H.; Ishizuka, T.; Kaji, A.
2012-04-01
When earthquake or torrential rainfall cause deep catastrophic landslides, landslide dams can be formed in mountainous region. If water overflows from the landslide dams, large scale debris flow can occurs and possibly causes serious disasters in the downward region. Debris flow caused by the overflow from landslide dam is possible to affect the larger area than normal debris flow and flash flood. It is important for both a decision maker and resident in the area to recognize the disaster prone area as early as possible. For that reason, it is important to establish a quick analysis method for estimating debris flow prone area caused by overflow from landslide dams under the emergency situation. This situation requires the method to have both accuracy and speed for release. Nonetheless these two factors have trade-off relationship. We recently developed the quick analysis method to estimate debris flow disaster prone area caused by overflow from landslide dams. The method including the ways of efficient survey and numerical simulation programs called QUAD-L (QUick Analysis system for Debris flow caused by Landslide dam overflow). Our quick analysis system was actually applied to show the area for evacuation against debris flow caused by overflow from landslide dam formed by the 2011 Typhoon Talas which hit mainly the central region of Japan on September 2-4th, 2011. In addition to background of this application, since May 1st, 2011, Erosion and Sediment Control (SABO) Department of the Ministry of Land, Infrastructure, Transport and Tourism, Japan (MLIT) launched a new scheme using above-mentioned quick analysis method.
Directory of Open Access Journals (Sweden)
Tan Chan Sin
2015-01-01
Full Text Available Productivity rate (Q or production rate is one of the important indicator criteria for industrial engineer to improve the system and finish good output in production or assembly line. Mathematical and statistical analysis method is required to be applied for productivity rate in industry visual overviews of the failure factors and further improvement within the production line especially for automated flow line since it is complicated. Mathematical model of productivity rate in linear arrangement serial structure automated flow line with different failure rate and bottleneck machining time parameters becomes the basic model for this productivity analysis. This paper presents the engineering mathematical analysis method which is applied in an automotive company which possesses automated flow assembly line in final assembly line to produce motorcycle in Malaysia. DCAS engineering and mathematical analysis method that consists of four stages known as data collection, calculation and comparison, analysis, and sustainable improvement is used to analyze productivity in automated flow assembly line based on particular mathematical model. Variety of failure rate that causes loss of productivity and bottleneck machining time is shown specifically in mathematic figure and presents the sustainable solution for productivity improvement for this final assembly automated flow line.
Borazjani, Iman; Westerdale, John; McMahon, Eileen M; Rajaraman, Prathish K; Heys, Jeffrey J; Belohlavek, Marek
2013-01-01
The left ventricle (LV) pumps oxygenated blood from the lungs to the rest of the body through systemic circulation. The efficiency of such a pumping function is dependent on blood flow within the LV chamber. It is therefore crucial to accurately characterize LV hemodynamics. Improved understanding of LV hemodynamics is expected to provide important clinical diagnostic and prognostic information. We review the recent advances in numerical and experimental methods for characterizing LV flows and focus on analysis of intraventricular flow fields by echocardiographic particle image velocimetry (echo-PIV), due to its potential for broad and practical utility. Future research directions to advance patient-specific LV simulations include development of methods capable of resolving heart valves, higher temporal resolution, automated generation of three-dimensional (3D) geometry, and incorporating actual flow measurements into the numerical solution of the 3D cardiovascular fluid dynamics.
Model and Method of Debris Flow Risk Zoning Based on Momentum Analysis
Institute of Scientific and Technical Information of China (English)
WEI Fangqiang; ZHANG Yu; HU Kaiheng; GAO Kechang
2006-01-01
A model of debris flow risk zoning is carried out with momentum analysis of debris flow. This model zones the debris flow inundation fan with density and velocity calculated by numerical simulation. The risk classification standard is determined according to the ultimate bearing capacities of different structures under impacting. And the ultimate bearing capacities are tested by impact failure experiment of destruction. Two structures typical in Chinese mountain towns, reinforced concrete frame construction and brickwork with concrete, are chosen in the experiment. The model makes debris flow risk zoning quantitative and the results comparable widely. The results differ much from that of other methods especially in the identification of medium and low risk zones.
Laser speckle imaging of rat retinal blood flow with hybrid temporal and spatial analysis method
Cheng, Haiying; Yan, Yumei; Duong, Timothy Q.
2009-02-01
Noninvasive monitoring of blood flow in retinal circulation will reveal the progression and treatment of ocular disorders, such as diabetic retinopathy, age-related macular degeneration and glaucoma. A non-invasive and direct BF measurement technique with high spatial-temporal resolution is needed for retinal imaging. Laser speckle imaging (LSI) is such a method. Currently, there are two analysis methods for LSI: spatial statistics LSI (SS-LSI) and temporal statistical LSI (TS-LSI). Comparing these two analysis methods, SS-LSI has higher signal to noise ratio (SNR) and TSLSI is less susceptible to artifacts from stationary speckle. We proposed a hybrid temporal and spatial analysis method (HTS-LSI) to measure the retinal blood flow. Gas challenge experiment was performed and images were analyzed by HTS-LSI. Results showed that HTS-LSI can not only remove the stationary speckle but also increase the SNR. Under 100% O2, retinal BF decreased by 20-30%. This was consistent with the results observed with laser Doppler technique. As retinal blood flow is a critical physiological parameter and its perturbation has been implicated in the early stages of many retinal diseases, HTS-LSI will be an efficient method in early detection of retina diseases.
Energy Technology Data Exchange (ETDEWEB)
Kucza, Witold, E-mail: witek@agh.edu.pl
2013-07-25
Graphical abstract: -- Highlights: •Former random walk approach for FIA simulations has been improved. •Random walk and uniform dispersion models have been used for FIA simulations. •Diffusivities have been optimized by genetic and the Levenberg–Marquardt methods. •Both approaches have given similar results in agreement with experimental ones. -- Abstract: Stochastic and deterministic simulations of dispersion in cylindrical channels on the Poiseuille flow have been presented. The random walk (stochastic) and the uniform dispersion (deterministic) models have been used for computations of flow injection analysis responses. These methods coupled with the genetic algorithm and the Levenberg–Marquardt optimization methods, respectively, have been applied for determination of diffusion coefficients. The diffusion coefficients of fluorescein sodium, potassium hexacyanoferrate and potassium dichromate have been determined by means of the presented methods and FIA responses that are available in literature. The best-fit results agree with each other and with experimental data thus validating both presented approaches.
Fractured porous medium flow analysis using numerical manifold method with independent covers
Zhang, Qi-Hua; Lin, Shao-Zhong; Xie, Zhi-Qiang; Su, Hai-Dong
2016-11-01
Due to the complexity of geometry and the difficulty of mesh discretization of 3D (three-dimensional) blocks cut by complexly distributed fractures, explicitly considering arbitrary fracture network in fractured porous medium (FPM) flow analysis is very challenging for various numerical methods. In this study, we developed a FPM flow model by taking full advantage of numerical manifold method (NMM) with independent covers. With the independent covers, arbitrarily-shaped 3D blocks identified by block-cutting analysis can be directly used as basic computational elements. Along the boundaries of the divided blocks, fractures elements are generated according to the fractures' apertures. Therefore, it is able to handle very complicated fracture network in 3D flow analysis without need to subdivide 3D blocks into computational meshes. In order to refine the meshes, we introduced artificial fractures with same material properties as surrounding rock into a fracture network, without need to coordinate with the shapes of the blocks. We demonstrated our new model on different 2D examples. At last, we applied our model to 2D and 3D examples with complexly distributed fractures, and achieved reasonable results. The results show that our model is very powerful to analyze fluid flow in arbitrarily and complexly fractured rock mass in 3D.
Pradipto; Purqon, Acep
2017-07-01
Lattice Boltzmann Method (LBM) is the novel method for simulating fluid dynamics. Nowadays, the application of LBM ranges from the incompressible flow, flow in the porous medium, until microflows. The common collision model of LBM is the BGK with a constant single relaxation time τ. However, BGK suffers from numerical instabilities. These instabilities could be eliminated by implementing LBM with multiple relaxation time. Both of those scheme have implemented for incompressible 2 dimensions lid-driven cavity. The stability analysis has done by finding the maximum Reynolds number and velocity for converged simulations. The accuracy analysis is done by comparing the velocity profile with the benchmark results from Ghia, et al and calculating the net velocity flux. The tests concluded that LBM with MRT are more stable than BGK, and have a similar accuracy. The maximum Reynolds number that converges for BGK is 3200 and 7500 for MRT respectively.
A new approach in cascade flow analysis using the finite element method
Baskharone, E.; Hamed, A.
1980-01-01
A new approach in analyzing the potential flow past cascades and single airfoils using the finite element method is developed. In this analysis the circulation around the airfoil is not externally imposed but is directly computed in the numerical solution. Different finite element discretization patterns, orders of piecewise approximation, and grid sizes are used in the solution. The results obtained are compared with existing experimental measurements and exact solutions in cascades and single airfoils.
Advanced real-time classification methods for flow cytometry data analysis and cell sorting
Leary, James F.; Reece, Lisa M.; Hokanson, James A.; Rosenblatt, Judah I.
2002-05-01
While many flow cytometric data analysis and 'discovery' methods have been developed, few of these have been applied to the problem of separating out purified cell subpopulations by cell sorting. The fundamental problem is that the data analysis techniques have been performed using relatively slow computational methods that take far more time than is allowed by the sort decision on a cell sorter (typically less than a millisecond). Thus cell sorting, which is really a form of 'real-time data classification,' is usually done with few, if any, multivariate statistical tools used either in the sort decision or in the evaluation of the correctness of the classification. We have developed new multivariate data analysis and 'data discovery' methods that can be implemented for real-time data classification for cell sorting using linked lookup tables. One multivariate 'data discovery' method, 'subtractive clustering,' has been used to find which clusters of cells are different between two or more files (cell samples) and to help guide analysis or sort boundaries for these cell subpopulations. Multivariate statistical methods (e.g. principal component analysis or discriminant function analysis) were implemented in linked lookup tables to establish analysis/sort boundaries that include 'costs (or penalties) of misclassification. Costs of misclassification provided a measure of the quality of the analysis/sort boundary and were expressed in simple terms that describe the tradeoff between yield and purity.
Solid rocket booster internal flow analysis by highly accurate adaptive computational methods
Huang, C. Y.; Tworzydlo, W.; Oden, J. T.; Bass, J. M.; Cullen, C.; Vadaketh, S.
1991-01-01
The primary objective of this project was to develop an adaptive finite element flow solver for simulating internal flows in the solid rocket booster. Described here is a unique flow simulator code for analyzing highly complex flow phenomena in the solid rocket booster. New methodologies and features incorporated into this analysis tool are described.
A Triple Staining Method for Accurate Cell Cycle Analysis Using Multiparameter Flow Cytometry
Directory of Open Access Journals (Sweden)
Lin Qiu
2013-12-01
Full Text Available Cell cycle analysis is important for cancer research. We present herein a novel method for accurate cell cycle analysis. This method analyzes the cell cycle by multiparameter flow cytometry based on simultaneously labeling the cell nuclear DNA, RNA, and phosphorylated mitotic nuclei protein, using Hoechst 33342, pyronin Y, and MPM-2-Cy5, respectively, and our results demonstrated that this method could effectively divide the cell cycle into G0, G1, S, G2, and M phases. We further tested this method using the clinical anticancer agents crizotinib and taxol, and the results clearly illustrated that crizotinib and taxol arrested Jurkat cells in G0 and M phase, respectively. These results indicate that this method could be a very useful tool for cytokinetic and pharmacological research.
Series solutions of stagnation slip flow and heat transfer by the homotopy analysis method
Institute of Scientific and Technical Information of China (English)
CHENG Jun; LIAO ShiJun; R. N. MOHAPATRA; K. VAJRAVELU
2009-01-01
An analytical approximation for the similarity solutions of the two- and three-dimensional stagnation slip flow and heat transfer is obtained by using the homotopy analysis method. This method is a series expansion method, but it is different from the perturbation technique, because it is independent of small physical parameters at all. Instead, it is based on a continuous mapping in topology so that it is applicable for not only weakly but also strongly nonlinear flow phenomena. Convergent [m,m] homotopy Pade approximants are obtained and compared with the numerical results and the numerical results. The effects of the slip length and the thermal slip constant β on the heat transfer characteristics are investigated and discussed.
Series solutions of stagnation slip flow and heat transfer by the homotopy analysis method
Institute of Scientific and Technical Information of China (English)
R.N.MOHAPATRA; K.VAJRAVELU
2009-01-01
An analytical approximation for the similarity solutions of the two-and three-dimensional stagnation slip flow and heat transfer is obtained by using the homotopy analysis method. This method is a series expansion method, but it is different from the perturbation technique, because it is independent of small physical parameters at all. Instead, it is based on a continuous mapping in topology so that it is applicable for not only weakly but also strongly nonlinear flow phenomena. Convergent [m,m] homotopy Padé approximants are obtained and compared with the numerical results and the asymptotic approximations. It is found that the homotopy Padé approximants agree well with the numerical results. The effects of the slip length and the thermal slip constant β on the heat transfer characteristics are investigated and discussed.
Flow analysis and design optimization methods for nozzle afterbody of a hypersonic vehicle
Baysal, Oktay
1991-01-01
This report summarizes the methods developed for the aerodynamic analysis and the shape optimization of the nozzle-afterbody section of a hypersonic vehicle. Initially, exhaust gases were assumed to be air. Internal-external flows around a single scramjet module were analyzed by solving the three dimensional Navier-Stokes equations. Then, exhaust gases were simulated by a cold mixture of Freon and Argon. Two different models were used to compute these multispecies flows as they mixed with the hypersonic airflow. Surface and off-surface properties were successfully compared with the experimental data. In the second phase of this project, the Aerodynamic Design Optimization with Sensitivity analysis (ADOS) was developed. Pre and post optimization sensitivity coefficients were derived and used in this quasi-analytical method. These coefficients were also used to predict inexpensively the flow field around a changed shape when the flow field of an unchanged shape was given. Starting with totally arbitrary initial afterbody shapes, independent computations were converged to the same optimum shape, which rendered the maximum axial thrust.
Flow Analysis: A Novel Approach For Classification.
Vakh, Christina; Falkova, Marina; Timofeeva, Irina; Moskvin, Alexey; Moskvin, Leonid; Bulatov, Andrey
2016-09-01
We suggest a novel approach for classification of flow analysis methods according to the conditions under which the mass transfer processes and chemical reactions take place in the flow mode: dispersion-convection flow methods and forced-convection flow methods. The first group includes continuous flow analysis, flow injection analysis, all injection analysis, sequential injection analysis, sequential injection chromatography, cross injection analysis, multi-commutated flow analysis, multi-syringe flow injection analysis, multi-pumping flow systems, loop flow analysis, and simultaneous injection effective mixing flow analysis. The second group includes segmented flow analysis, zone fluidics, flow batch analysis, sequential injection analysis with a mixing chamber, stepwise injection analysis, and multi-commutated stepwise injection analysis. The offered classification allows systematizing a large number of flow analysis methods. Recent developments and applications of dispersion-convection flow methods and forced-convection flow methods are presented.
Directory of Open Access Journals (Sweden)
E. Rajabi
2014-01-01
Full Text Available In this research a direct numerical simulation (DNS of turbulent flow is performed in a geometrically standard case like plane channel flow. Pseudo spectral (PS method is used due to geometry specifications and very high accuracy achieved despite relatively few grid points. A variable time-stepping algorithm is proposed which may reduce requirement of computational cost in simulation of such wall-bounded flow. Channel flow analysis is performed with both constant and varied time-step for 128 × 65×128 grid points. The time advancement is carried out by implicit third-order backward differentiation scheme for linear terms and explicit forward Euler for nonlinear convection term. PS method is used in Cartesian coordinates with Chebychev polynomial expansion in normal direction for one non-periodic boundary condition. Also Fourier series is employed in stream-wise and span-wise directions for two periodic boundary conditions. The friction Reynolds number is about Reτ=175 based on a friction velocity and channel half width. Standard common rotational form was chosen for discritization of nonlinear convective term of Navier-Stocks equation. The comparison is made between turbulent quantities such as the turbulent statistics, Reynolds stress, wall shear velocity, standard deviation of (u and total normalized energy of instantaneous velocities in both time-discretization methods. The results show that if final decision rests on economics, the proposed variable time-stepping algorithm will be proper choice which satisfies the accuracy and reduces the computational cost.
Trajectory Analysis of Fuel Injection into Supersonic Cross Flow Based on Schlieren Method
Institute of Scientific and Technical Information of China (English)
YANG Hui; LI Feng; SUN Baigang
2012-01-01
Trajectory analysis of fuel injection into supersonic cross flow is studied in this paper.A directly-connected wind tunnel is constructed to provide stable supersonic freestream.Based on the test rig,the schlieren system is established to reveal the fuel injection process visually.Subsequently,the method of quantitative schlieren is adopted to obtain data of both fuel/air interface and bow shock with the aid of Photoshop and Origin.Finally,the mechanism based on two influential factors of fuel injection angle and fuel injection driven pressure,is researched by vector analysis.A dimensionless model is deduced and analyzed.The curve fitting result is achieved.The relationship between the data and the two influential factors is established.The results provide not only the quantitative characteristics of the fuel injection in supersonic cross flow but also the valuable reference for the future computational simulation.
Determination of cyanide by a flow injection analysis-atomic absorption spectrometric method.
López Gómez, A V; Martínez Calatayud, J
1998-10-01
A new flow injection analysis (FIA) procedure is proposed for the indirect atomic absorption spectrometric determination of cyanide. The FIA manifold is based on the insertion of the sample into a distilled water carrier, then the sample flows through a solid-phase reactor filled with silver iodide entrapped in polymeric resin beads. The calibration graph is linear over the range 0.2-6.0 mg l-1 of cyanide (correlation coefficient 0.9974), the detection limit is 0.1 mg l-1, the sample throughput is 193 h-1 and the RSD is 0.8%. The method is simple, quick and more selective than other published FIA procedures. The reproducibility obtained by using different solid-phase reactors and solutions is in the range 2.2-3.1% (RSD). The method was applied to the determination of cyanide in commercial samples such as pharmaceutical formulations and industrial electrolytic baths.
NetFCM: A Semi-Automated Web-Based Method for Flow Cytometry Data Analysis
DEFF Research Database (Denmark)
Frederiksen, Juliet Wairimu; Buggert, Marcus; Karlsson, Annika C.
2014-01-01
data analysis has become more complex and labor-intensive than previously. We have therefore developed a semi-automatic gating strategy (NetFCM) that uses clustering and principal component analysis (PCA) together with other statistical methods to mimic manual gating approaches. NetFCM is an online...... corresponding to those obtained by manual gating strategies. These data demonstrate that NetFCM has the potential to identify relevant T cell populations by mimicking classical FCM data analysis and reduce the subjectivity and amount of time associated with such analysis. (c) 2014 International Society......Multi-parametric flow cytometry (FCM) represents an invaluable instrument to conduct single cell analysis and has significantly increased our understanding of the immune system. However, due to new techniques allowing us to measure an increased number of phenotypes within the immune system, FCM...
This method provides a procedure for the determination of ammonia in estuarine and coastal waters. The method is based upon the indophenol reaction,1-5 here adapted to automated gas-segmented continuous flow analysis.
Effective star tracking method based on optical flow analysis for star trackers.
Sun, Ting; Xing, Fei; Wang, Xiaochu; Li, Jin; Wei, Minsong; You, Zheng
2016-12-20
Benefiting from rapid development of imaging sensor technology, modern optical technology, and a high-speed computing chip, the star tracker's accuracy, dynamic performance, and update rate have been greatly improved with low power consumption and miniature size. The star tracker is currently one of the most competitive attitude measurement sensors. However, due to restrictions of the optical imaging system, difficulties still exist in moving star spot detection and star tracking when in special motion conditions. An effective star tracking method based on optical flow analysis for star trackers is proposed in this paper. Spot-based optical flow, based on a gray gradient between two adjacent star images, is analyzed to distinguish the star spot region and obtain an accurate star spot position so that the star tracking can keep continuous under high dynamic conditions. The obtained star vectors and extended Kalman filter (EKF) are then combined to conduct an angular velocity estimation to ensure region prediction of the star spot; this can be combined with the optical flow analysis result. Experiment results show that the method proposed in this paper has advantages in conditions of large angular velocity and large angular acceleration, despite the presence of noise. Higher functional density and better performance can be achieved; thus, the star tracker can be more widely applied in small satellites, remote sensing, and other complex space missions.
Methods and Models for Capacity and Patient Flow Analysis in Hospital Sector
DEFF Research Database (Denmark)
Kozlowski, Dawid
This thesis is concerned about the novel applications of operations research methods for capacity and flow analysis within hospital sector. The first part of the thesis presents a detailed Discrete-Event Simulation (DES) model that has been developed as an analytical tool designed to facilitate...... perspective with use of a queueing model. The cost minimization approach is used to show the benefits and trade-offs involved. The aim is to support the enhancement of the quality of elective patient care, to be brought about by better understanding of the policy implications by hospital planners...
MHD flow of a viscous fluid on a nonlinear porous shrinking sheet with homotopy analysis method
Institute of Scientific and Technical Information of China (English)
S. Nadeem; Anwar Hussain
2009-01-01
The present paper investigates the magnetohydrodynamic (MHD) flow of a viscous fluid towards a nonlinear porous shrinking sheet. The governing equations are simplified by similarity transformations. The reduced problem is then solved by the homotopy analysis method. The pertinent parameters appearing in the problem are discussed graphically and presented in tables. It is found that the shrinking solutions exist in the presence of MHD. It is also observed from the tables that the solutions for f"(0) with different values of parameters are convergent.
Initial assessment of facial nerve paralysis based on motion analysis using an optical flow method.
Samsudin, Wan Syahirah W; Sundaraj, Kenneth; Ahmad, Amirozi; Salleh, Hasriah
2016-01-01
An initial assessment method that can classify as well as categorize the severity of paralysis into one of six levels according to the House-Brackmann (HB) system based on facial landmarks motion using an Optical Flow (OF) algorithm is proposed. The desired landmarks were obtained from the video recordings of 5 normal and 3 Bell's Palsy subjects and tracked using the Kanade-Lucas-Tomasi (KLT) method. A new scoring system based on the motion analysis using area measurement is proposed. This scoring system uses the individual scores from the facial exercises and grades the paralysis based on the HB system. The proposed method has obtained promising results and may play a pivotal role towards improved rehabilitation programs for patients.
Geostatistical Sampling Methods for Efficient Uncertainty Analysis in Flow and Transport Problems
Liodakis, Stylianos; Kyriakidis, Phaedon; Gaganis, Petros
2015-04-01
In hydrogeological applications involving flow and transport of in heterogeneous porous media the spatial distribution of hydraulic conductivity is often parameterized in terms of a lognormal random field based on a histogram and variogram model inferred from data and/or synthesized from relevant knowledge. Realizations of simulated conductivity fields are then generated using geostatistical simulation involving simple random (SR) sampling and are subsequently used as inputs to physically-based simulators of flow and transport in a Monte Carlo framework for evaluating the uncertainty in the spatial distribution of solute concentration due to the uncertainty in the spatial distribution of hydraulic con- ductivity [1]. Realistic uncertainty analysis, however, calls for a large number of simulated concentration fields; hence, can become expensive in terms of both time and computer re- sources. A more efficient alternative to SR sampling is Latin hypercube (LH) sampling, a special case of stratified random sampling, which yields a more representative distribution of simulated attribute values with fewer realizations [2]. Here, term representative implies realizations spanning efficiently the range of possible conductivity values corresponding to the lognormal random field. In this work we investigate the efficiency of alternative methods to classical LH sampling within the context of simulation of flow and transport in a heterogeneous porous medium. More precisely, we consider the stratified likelihood (SL) sampling method of [3], in which attribute realizations are generated using the polar simulation method by exploring the geometrical properties of the multivariate Gaussian distribution function. In addition, we propose a more efficient version of the above method, here termed minimum energy (ME) sampling, whereby a set of N representative conductivity realizations at M locations is constructed by: (i) generating a representative set of N points distributed on the
Directory of Open Access Journals (Sweden)
Johan Debayle
2011-05-01
Full Text Available An image analysis method has been developed in order to compute the velocity field of a granular medium (sand grains, mean diameter 600 μm submitted to different kinds of mechanical stresses. The differential method based on optical flow conservation consists in describing a dense motion field with vectors associated to each pixel. A multiscale, coarse-to-fine, analytical approach through tailor sized windows yields the best compromise between accuracy and robustness of the results, while enabling an acceptable computation time. The corresponding algorithmis presented and its validation discussed through different tests. The results of the validation tests of the proposed approach show that the method is satisfactory when attributing specific values to parameters in association with the size of the image analysis window. An application in the case of vibrated sand has been studied. An instrumented laboratory device provides sinusoidal vibrations and enables external optical observations of sand motion in 3D transparent boxes. At 50 Hz, by increasing the relative acceleration G, the onset and development of two convective rolls can be observed. An ultra fast camera records the grain avalanches, and several pairs of images are analysed by the proposed method. The vertical velocity profiles are deduced and allow to precisely quantify the dimensions of the fluidized region as a function of G.
Multi-class continuum traffic flow models: Analysis and simulation methods
Van Wageningen-Kessels, F.L.M.
2013-01-01
How to model and simulate traffic flow including different vehicles such as cars and trucks? This dissertation answers this question by analyzing existing models and simulation methods and by developing new ones. The new model (Fastlane) describes traffic as a continuum flow while accounting for dif
Emerging flow injection mass spectrometry methods for high-throughput quantitative analysis.
Nanita, Sergio C; Kaldon, Laura G
2016-01-01
Where does flow injection analysis mass spectrometry (FIA-MS) stand relative to ambient mass spectrometry (MS) and chromatography-MS? Improvements in FIA-MS methods have resulted in fast-expanding uses of this technique. Key advantages of FIA-MS over chromatography-MS are fast analysis (typical run time quantitative screening of chemicals needs to be performed rapidly and reliably. The FIA-MS methods discussed herein have demonstrated quantitation of diverse analytes, including pharmaceuticals, pesticides, environmental contaminants, and endogenous compounds, at levels ranging from parts-per-billion (ppb) to parts-per-million (ppm) in very complex matrices (such as blood, urine, and a variety of foods of plant and animal origin), allowing successful applications of the technique in clinical diagnostics, metabolomics, environmental sciences, toxicology, and detection of adulterated/counterfeited goods. The recent boom in applications of FIA-MS for high-throughput quantitative analysis has been driven in part by (1) the continuous improvements in sensitivity and selectivity of MS instrumentation, (2) the introduction of novel sample preparation procedures compatible with standalone mass spectrometric analysis such as salting out assisted liquid-liquid extraction (SALLE) with volatile solutes and NH4(+) QuEChERS, and (3) the need to improve efficiency of laboratories to satisfy increasing analytical demand while lowering operational cost. The advantages and drawbacks of quantitative analysis by FIA-MS are discussed in comparison to chromatography-MS and ambient MS (e.g., DESI, LAESI, DART). Generally, FIA-MS sits 'in the middle' between ambient MS and chromatography-MS, offering a balance between analytical capability and sample analysis throughput suitable for broad applications in life sciences, agricultural chemistry, consumer safety, and beyond.
Analysis of flow structures in supersonic plane mixing layers using the POD method
Institute of Scientific and Technical Information of China (English)
YANG Qin; FU Song
2008-01-01
The proper orthogonal decomposition (POD) method was applied to analyzing the database obtained from the direct numerical simulation (DNS) of supersonic plane mixing layers. The effect of different forms of the inner products in the POD method was investigated. It was observed that the mean flow contributes to a predominant part of the total flow energy, and the energy spectrum of the turbulence fluctuations covers a wide range of POD modes. The patterns of leading (high energy) POD modes reveal that the flow structures exhibit spanwise counter rotating rolls, as well as oblique vortices. These flow patterns are insensitive to the velocity of the observer. As the convective Mach number increases, the energy spectrum be-comes wider, the leading POD modes contain more complicated structures, and the flow becomes more chaotic.
Analysis of flow structures in supersonic plane mixing layers using the POD method
Institute of Scientific and Technical Information of China (English)
2008-01-01
The proper orthogonal decomposition(POD) method was applied to analyzing the database obtained from the direct numerical simulation(DNS) of supersonic plane mixing layers.The effect of different forms of the inner products in the POD method was investigated.It was observed that the mean flow contributes to a predominant part of the total flow energy,and the energy spectrum of the turbulence fluctuations covers a wide range of POD modes.The patterns of leading(high energy) POD modes reveal that the flow structures exhibit spanwise counter rotating rolls,as well as oblique vortices.These flow patterns are insensitive to the velocity of the observer.As the convective Mach number increases,the energy spectrum be-comes wider,the leading POD modes contain more complicated structures,and the flow becomes more chaotic.
Analysis of liquid steel flow in a multi-strand tundish using numerical methods
Directory of Open Access Journals (Sweden)
P. Warzecha
2015-07-01
Full Text Available The article presents the results of liquid steel flow and mixing in tundish when applying turbulence inhibitor to modernize the tundish working zone. The flow of six-strand continuous casting tundish of a trough-type was investigated with numerical modeling. For turbulence modeling, the Reynolds-Averaged Navier-Stokes (RANS equation and the Large Eddy Simulation (LES methods have been used. Numerical simulations are carried out with the finitevolume commercial code AnsysFluent.
Corrie, S R; Lawrie, G A; Battersby, B J; Ford, K; Rühmann, A; Koehler, K; Sabath, D E; Trau, M
2008-05-01
Bead-based assays are in demand for rapid genomic and proteomic assays for both research and clinical purposes. Standard quantitative procedures addressing raw data quality and analysis are required to ensure the data are consistent and reproducible across laboratories independent of flow platform. Quantitative procedures have been introduced spanning raw histogram analysis through to absolute target quantitation. These included models developed to estimate the absolute number of sample molecules bound per bead (Langmuir isotherm), relative quantitative comparisons (two-sided t-tests), and statistical analyses investigating the quality of raw fluorescence data. The absolute target quantitation method revealed a concentration range (below probe saturation) of Cy5-labeled synthetic cytokeratin 19 (K19) RNA of c.a. 1 x 10(4) to 500 x 10(4) molecules/bead, with a binding constant of c.a. 1.6 nM. Raw hybridization frequency histograms were observed to be highly reproducible across 10 triplex assay replicates and only three assay replicates were required to distinguish overlapping peaks representing small sequence mismatches. This study provides a quantitative scheme for determining the absolute target concentration in nucleic acid hybridization reactions and the equilibrium binding constants for individual probe/target pairs. It is envisaged that such studies will form the basis of standard analytical procedures for bead-based cytometry assays to ensure reproducibility in inter- and intra-platform comparisons of data between laboratories. (c) 2008 International Society for Advancement of Cytometry.
Directory of Open Access Journals (Sweden)
Elmano Pinto
2014-12-01
Full Text Available Microfluidic devices are electrical/mechanical systems that offer the ability to work with minimal sample volumes, short reactions times, and have the possibility to perform massive parallel operations. An important application of microfluidics is blood rheology in microdevices, which has played a key role in recent developments of lab-on-chip devices for blood sampling and analysis. The most popular and traditional method to fabricate these types of devices is the polydimethylsiloxane (PDMS soft lithography technique, which requires molds, usually produced by photolithography. Although the research results are extremely encouraging, the high costs and time involved in the production of molds by photolithography is currently slowing down the development cycle of these types of devices. Here we present a simple, rapid, and low-cost nonlithographic technique to create microfluidic systems for biomedical applications. The results demonstrate the ability of the proposed method to perform cell free layer (CFL measurements and the formation of microbubbles in continuous blood flow.
Second-order explicit finite-difference methods for transient-flow analysis
Chaudhry, M. H.; Hussaini, M. Y.
1983-01-01
Three second-order accurate numerical methods - MacCormack's method, Lambda scheme and Gabutti scheme - are introduced to solve the quasi-linear, hyperbolic partial differential equations describing transient flows in closed conduits. The details of these methods and the treatment of boundary conditions are presented and the results computed by using these methods for a typical piping system are compared. It is shown that for the same accuracy, second-order methods require considerably lesser number of computational nodes and computer time as compared to those required by the first-order methods.
Energy Technology Data Exchange (ETDEWEB)
Arai, M.; Hashimoto, K.; Suga, S.; Matsuoka, A. (Kawasaki Heavy Industries, Ltd., Tokyo (Japan))
1992-10-20
Numerical fluid dynamics is used to solve numerically the Navier-Stokes equations including viscosity using a computer for the purpose of evaluating aerodynamic performance of compressor cascades, an element to constitute a jet engine. This paper discusses effectiveness and problems in this computation. A viscous flow analysis using this method was applied to actual two-dimensional compressor cascades that work in transonic regions. The analytic result may be summarized as follows: The method has high analytic accuracy and can predict aerodynamic characteristics if no separation occurs or it is limited in a flow field; however, the method does not assure quantitative accuracy for a flow accompanying separation and strong in non-steadiness; at this stage the method cannot be applied to three-dimensional problems, but is effective in identifying a flow field qualitatively; and while the supercomputer VP 200 required only two to three minutes to analyze a two-dimensional flow with 14000 lattices, the three-dimensional viscosity analysis required five hours. This method may be used effectively in a basic discussion stage for the initial design and in a simulation stage for improving a design. 11 refs., 18 figs., 2 tabs.
Advanced Methods for Aircraft Engine Thrust and Noise Benefits: Nozzle-Inlet Flow Analysis
Morgan, Morris H.; Gilinsky, Mikhail M.
2001-01-01
Three connected sub-projects were conducted under reported project. Partially, these sub-projects are directed to solving the problems conducted by the HU/FM&AL under two other NASA grants. The fundamental idea uniting these projects is to use untraditional 3D corrugated nozzle designs and additional methods for exhaust jet noise reduction without essential thrust lost and even with thrust augmentation. Such additional approaches are: (1) to add some solid, fluid, or gas mass at discrete locations to the main supersonic gas stream to minimize the negative influence of strong shock waves forming in propulsion systems; this mass addition may be accompanied by heat addition to the main stream as a result of the fuel combustion or by cooling of this stream as a result of the liquid mass evaporation and boiling; (2) to use porous or permeable nozzles and additional shells at the nozzle exit for preliminary cooling of exhaust hot jet and pressure compensation for non-design conditions (so-called continuous ejector with small mass flow rate; and (3) to propose and analyze new effective methods fuel injection into flow stream in air-breathing engines. Note that all these problems were formulated based on detailed descriptions of the main experimental facts observed at NASA Glenn Research Center. Basically, the HU/FM&AL Team has been involved in joint research with the purpose of finding theoretical explanations for experimental facts and the creation of the accurate numerical simulation technique and prediction theory for solutions for current problems in propulsion systems solved by NASA and Navy agencies. The research is focused on a wide regime of problems in the propulsion field as well as in experimental testing and theoretical and numerical simulation analysis for advanced aircraft and rocket engines. The F&AL Team uses analytical methods, numerical simulations, and possible experimental tests at the Hampton University campus. We will present some management activity
Analysis of High Order Difference Methods for Multiscale Complex Compressible Flows
Sjoegreen, Bjoern; Yee, H. C.; Tang, Harry (Technical Monitor)
2002-01-01
Accurate numerical simulations of complex multiscale compressible viscous flows, especially high speed turbulence combustion and acoustics, demand high order schemes with adaptive numerical dissipation controls. Standard high resolution shock-capturing methods are too dissipative to capture the small scales and/or long-time wave propagations without extreme grid refinements and small time steps. An integrated approach for the control of numerical dissipation in high order schemes with incremental studies was initiated. Here we further refine the analysis on, and improve the understanding of the adaptive numerical dissipation control strategy. Basically, the development of these schemes focuses on high order nondissipative schemes and takes advantage of the progress that has been made for the last 30 years in numerical methods for conservation laws, such as techniques for imposing boundary conditions, techniques for stability at shock waves, and techniques for stable and accurate long-time integration. We concentrate on high order centered spatial discretizations and a fourth-order Runge-Kutta temporal discretizations as the base scheme. Near the bound-aries, the base scheme has stable boundary difference operators. To further enhance stability, the split form of the inviscid flux derivatives is frequently used for smooth flow problems. To enhance nonlinear stability, linear high order numerical dissipations are employed away from discontinuities, and nonlinear filters are employed after each time step in order to suppress spurious oscillations near discontinuities to minimize the smearing of turbulent fluctuations. Although these schemes are built from many components, each of which is well-known, it is not entirely obvious how the different components be best connected. For example, the nonlinear filter could instead have been built into the spatial discretization, so that it would have been activated at each stage in the Runge-Kutta time stepping. We could think
Prediction and analysis of 3D hydrofoil and propeller under potential flow using panel method
Directory of Open Access Journals (Sweden)
Chen Chen-Wei
2016-01-01
Full Text Available Potential flow over an airfoil plays an important historical role in the theory of airfoil. The governing equation for potential flow is Laplace’s equation. One of Green’s identities can be used to write a solution to Laplace’s equation as a boundary integral. Using distributions of singularity solutions and determining their strength via the boundary conditions is the essence of panel method. This paper introduces a quick prediction method of three-dimensional hydrofoil and propeller performance based on panel method. The surface of hydrofoil and propeller is divided into numbers of quadrilateral panels. Combined sources with doublets singularities will be distributed on the corners of panels. Calculated blade pressure distributions of hydrofoil and propeller agree well with experimental data. Several sample calculations have been included using panel method.
Energy Technology Data Exchange (ETDEWEB)
Dai, Heng [Pacific Northwest National Laboratory, Richland Washington USA; Chen, Xingyuan [Pacific Northwest National Laboratory, Richland Washington USA; Ye, Ming [Department of Scientific Computing, Florida State University, Tallahassee Florida USA; Song, Xuehang [Pacific Northwest National Laboratory, Richland Washington USA; Zachara, John M. [Pacific Northwest National Laboratory, Richland Washington USA
2017-05-01
Sensitivity analysis is an important tool for quantifying uncertainty in the outputs of mathematical models, especially for complex systems with a high dimension of spatially correlated parameters. Variance-based global sensitivity analysis has gained popularity because it can quantify the relative contribution of uncertainty from different sources. However, its computational cost increases dramatically with the complexity of the considered model and the dimension of model parameters. In this study we developed a hierarchical sensitivity analysis method that (1) constructs an uncertainty hierarchy by analyzing the input uncertainty sources, and (2) accounts for the spatial correlation among parameters at each level of the hierarchy using geostatistical tools. The contribution of uncertainty source at each hierarchy level is measured by sensitivity indices calculated using the variance decomposition method. Using this methodology, we identified the most important uncertainty source for a dynamic groundwater flow and solute transport in model at the Department of Energy (DOE) Hanford site. The results indicate that boundary conditions and permeability field contribute the most uncertainty to the simulated head field and tracer plume, respectively. The relative contribution from each source varied spatially and temporally as driven by the dynamic interaction between groundwater and river water at the site. By using a geostatistical approach to reduce the number of realizations needed for the sensitivity analysis, the computational cost of implementing the developed method was reduced to a practically manageable level. The developed sensitivity analysis method is generally applicable to a wide range of hydrologic and environmental problems that deal with high-dimensional spatially-distributed parameters.
Analysis of novel geometry-independent method for dialysis access pressure-flow monitoring
Directory of Open Access Journals (Sweden)
Panduranga Harsha
2008-11-01
Full Text Available Abstract Background End-stage renal disease (ESRD confers a large health-care burden for the United States, and the morbidity associated with vascular access failure has stimulated research into detection of vascular access stenosis and low flow prior to thrombosis. We present data investigating the possibility of using differential pressure (ΔP monitoring to estimate access flow (Q for dialysis access monitoring, with the goal of utilizing micro-electro-mechanical systems (MEMS pressure sensors integrated within the shaft of dialysis needles. Methods A model of the arteriovenous graft fluid circuit was used to study the relationship between Q and the ΔP between two dialysis needles placed 2.5–20.0 cm apart. Tubing was varied to simulate grafts with inner diameters of 4.76–7.95 mm. Data were compared with values from two steady-flow models. These results, and those from computational fluid dynamics (CFD modeling of ΔP as a function of needle position, were used to devise and test a method of estimating Q using ΔP and variable dialysis pump speeds (variable flow that diminishes dependence on geometric factors and fluid characteristics. Results In the fluid circuit model, ΔP increased with increasing volume flow rate and with increasing needle-separation distance. A nonlinear model closely predicts this ΔP-Q relationship (R2 > 0.98 for all graft diameters and needle-separation distances tested. CFD modeling suggested turbulent needle effects are greatest within 1 cm of the needle tip. Utilizing linear, quadratic and combined variable flow algorithms, dialysis access flow was estimated using geometry-independent models and an experimental dialysis system with the pressure sensors separated from the dialysis needle tip by distances ranging from 1 to 5 cm. Real-time ΔP waveform data were also observed during the mock dialysis treatment, which may be useful in detecting low or reversed flow within the access. Conclusion With further
Simple Rheological Analysis Method of Spinnable-Polymer Flow Properties Using MFI Tester
Directory of Open Access Journals (Sweden)
Basel Younes
2015-01-01
Full Text Available Rheological characterization of polymers explains the flow behaviour and viscoelastic properties and tests fibre-forming ability. The current method investigates the viscoelastic properties and morphology of polymers and finds the rheological data and the right polymer viscosity, which is determining the best processing temperature. The right processing temperature saves the power, the material, and the time needed for production. After calculating polymers viscosity by using MFI tester, the method investigates rheological properties and surface shape at different temperatures and loads. The method could apply to other polymers to find the viscosity-temperature change and to set the best processing temperature.
On The Analysis of Labyrinth Seal Flow Induced Vibration by Oscillating Fluid Mechanics Method
Institute of Scientific and Technical Information of China (English)
ChenZuoyi; JingYouhao; 等
1994-01-01
A numerical model and a solution method to analyze the labyrinth seal flow induced vibration by Oscillating Fluid Mechanics Method(OFMM) are presented in this paper,including the basic equations and solution procedure to determine the oscillating velocity,pressure and the dynamic characteristic coefficients of Labyrinth seal such as the stiffness coefficients and damping coefficients.The results show that this method has the advantages of both less time consuming and high accuracy.In addition it can be applied to the field diagnosis of the vibration of the axis of turbomachinery system.
Complexity Analysis of New Task Allocation Problem Using Network Flow Method on Multicore Clusters
Directory of Open Access Journals (Sweden)
Jixiang Yang
2014-01-01
Full Text Available The task allocation problem (TAP generally aims to minimize total execution cost and internode communication cost in traditional parallel computing systems. New TAP (NTAP considering additive intranode communication cost in emerging multicore cluster systems is investigated in this paper. We analyze the complexity of NTAP with network flow method and conclude that the intranode communication cost is a key to the complexity of NTAP, and prove that (1 the NTAP can be cast as a generalized linear network minimum cost flow problem and can be solved in O(m2n4 time if the intranode communication cost equals the internode communication cost, and (2 the NTAP can be cast as a generalized convex cost network minimum cost flow problem and can be solved in polynomial time if the intranode communication cost is more than the internode communication cost. More in particular, the uniform cost NTAP can be cast as a convex cost flow problem and can be solved in O(m2n2log(m+n time. Furthermore, solutions to the NTAP are also discussed. Our work extends currently known theoretical results and the theorems and conclusions presented in this paper can provide theoretical basis for task allocating strategies on multicore clusters.
Spectral Homotopy Analysis Method for PDEs That Model the Unsteady Von Kàrmàn Swirling Flow
Directory of Open Access Journals (Sweden)
Zodwa Makukula
2014-01-01
Full Text Available A spectral homotopy analysis method (SHAM is used to find numerical solutions for the unsteady viscous flow problem due to an infinite rotating disk. The problem is governed by a set of two fully coupled nonlinear partial differential equations. The method was originally introduced for solutions of nonlinear ordinary differential equations. In this study, its application is extended to a system of nonlinear partial differential equations (PDEs that model the unsteady von Kàrmàn swirling flow. Numerical values of the pertinent flow properties were generated and validated against results obtained using the Keller-box numerical scheme. The results indicate that the present method is very accurate and can be used as an efficient tool for solving nonlinear PDEs of the type discussed in this paper.
Rotor wake and flow analysis using a coupled Eulerian–Lagrangian method
Directory of Open Access Journals (Sweden)
Yongjie Shi
2016-01-01
Full Text Available A coupled Eulerian–Lagrangian methodology was developed in this paper in order to provide an efficient and accurate tool for rotor wake and flow prediction. A Eulerian-based Reynolds-averaged Navier–Stokes (RANS solver was employed to simulate the grid-covered near-body zone, and a grid-free Lagrangian-based viscous wake method (VWM was implemented to model the complicated rotor-wake dynamics in the off-body wake zone. A carefully designed coupling strategy was developed to pass the flow variables between two solvers. A sample case of a forward flying rotor was performed first in order to show the capabilities of the VWM for wake simulations. Next, the coupled method was applied to rotors in several representative flight conditions. Excellent agreement regarding wake geometry, chordwise pressure distribution and sectional normal force with available experimental data demonstrated the validity of the method. In addition, a comparison with the full computational fluid dynamics (CFD method is presented to illustrate the efficiency and accuracy of the proposed coupled method.
Directory of Open Access Journals (Sweden)
Xingwen Zhu
2015-01-01
Full Text Available Smoothing analysis process of distributive red-black Jacobi relaxation in multigrid method for solving 2D Stokes flow is mainly investigated on the nonstaggered grid by using local Fourier analysis (LFA. For multigrid relaxation, the nonstaggered discretizing scheme of Stokes flow is generally stabilized by adding an artificial pressure term. Therefore, an important problem is how to determine the zone of parameter in adding artificial pressure term in order to make stabilization of the algorithm for multigrid relaxation. To end that, a distributive red-black Jacobi relaxation technique for the 2D Stokes flow is established. According to the 2h-harmonics invariant subspaces in LFA, the Fourier representation of the distributive red-black Jacobi relaxation for discretizing Stokes flow is given by the form of square matrix, whose eigenvalues are meanwhile analytically computed. Based on optimal one-stage relaxation, a mathematical relation of the parameter in artificial pressure term between the optimal relaxation parameter and related smoothing factor is well yielded. The analysis results show that the numerical schemes for solving 2D Stokes flow by multigrid method on the distributive red-black Jacobi relaxation have a specified convergence parameter zone of the added artificial pressure term.
Lu, D.; Takizawa, A.; Kondo, S.
A newly developed ``physical component boundary fitted coordinate (PCBFC) method'' is extended for the analysis of free-surface flows coupled with moving boundaries. Extra techniques are employed to deal with the coupling movement of the free surface and moving boundaries. After the validation of the extension by several benchmark problems, the method is successfully applied for the first time to the simulation of overflow-induced vibration of the weir coupled with sloshing of the free-surface liquid.
Directory of Open Access Journals (Sweden)
Mohammad Mehdi Rashidi
2010-01-01
Full Text Available We investigated an axisymmetric unsteady two-dimensional flow of nonconducting, incompressible second grade fluid between two circular plates. The similarity transformation is applied to reduce governing partial differential equation (PDE to a nonlinear ordinary differential equation (ODE in dimensionless form. The resulting nonlinear boundary value problem is solved using homotopy analysis method and numerical method. The effects of appropriate dimensionless parameters on the velocity profiles are studied. The total resistance to the upper plate has been calculated.
A new spreadsheet method for the analysis of bivariate flow cytometric data
Directory of Open Access Journals (Sweden)
Isacke Clare M
2004-03-01
Full Text Available Abstract Background A useful application of flow cytometry is the investigation of cell receptor-ligand interactions. However such analyses are often compromised due to problems interpreting changes in ligand binding where the receptor expression is not constant. Commonly, problems are encountered due to cell treatments resulting in altered receptor expression levels, or when cell lines expressing a transfected receptor with variable expression are being compared. To overcome this limitation we have developed a Microsoft Excel spreadsheet that aims to automatically and effectively simplify flow cytometric data and perform statistical tests in order to provide a clearer graphical representation of results. Results To demonstrate the use and advantages of this new spreadsheet method we have investigated the binding of the transmembrane adhesion receptor CD44 to its ligand hyaluronan. In the first example, phorbol ester treatment of cells results in both increased CD44 expression and increased hyaluronan binding. By applying the spreadsheet method we effectively demonstrate that this increased ligand binding results from receptor activation. In the second example we have compared AKR1 cells transfected either with wild type CD44 (WT CD44 or a mutant with a truncated cytoplasmic domain (CD44-T. These two populations do not have equivalent receptor expression levels but by using the spreadsheet method hyaluronan binding could be compared without the need to generate single cell clones or FACS sorting the cells for matching CD44 expression. By this method it was demonstrated that hyaluronan binding requires a threshold expression of CD44 and that this threshold is higher for CD44-T. However, at high CD44-T expression, binding was equivalent to WT CD44 indicating that the cytoplasmic domain has a role in presenting the receptor at the cell surface in a form required for efficient hyaluronan binding rather than modulating receptor activity. Conclusion
Erdos, J. I.; Alzner, E.
1977-01-01
A numerical method of solution of the inviscid, compressible, two-dimensional unsteady flow on a blade-to-blade stream surface through a stage (rotor and stator) or a single blade row of an axial flow compressor or fan is described. A cyclic procedure has been developed for representation of adjacent blade-to-blade passages which asymptotically achieves the correct phase between all passages of a stage. A shock-capturing finite difference method is employed in the interior of the passage, and a method of characteristics technique is used at the boundaries. The blade slipstreams form two of the passage boundaries and are treated as moving contact surfaces capable of supporting jumps in entropy and tangential velocity. The Kutta condition is imposed by requiring the slipstreams to originate at the trailing edges, which are assumed to be sharp. Results are presented for several transonic fan rotors and compared with available experimental data, consisting of holographic observations of shock structure and pressure contour maps. A subcritical stator solution is also compared with results from a relaxation method. Finally, a periodic solution for a stage consisting of 44 rotor blades and 46 stator blades is discussed.
APPLICATION OF CHEMOMETRICS FOR ANALYSIS OF BIOAEROSOLS BY FLOW-OPTICAL METHOD
Directory of Open Access Journals (Sweden)
E. S. Khudyakov
2016-01-01
Full Text Available Subject of Research. The informativity of detection channels for bioaerosol analyzer is investigated. Analyzer operation is based on flow-optical method. Method. Measurements of fluorescence and the light scattering of separate bioaerosol particles were performed in five and two spectral ranges, correspondingly. The signals of soil dust particles were registered and used as an imitation of background atmospheric particles. For fluorescenceinduction of bioaerosol particles we used light sources: a laser one with a wavelength equal to 266 nm and 365 nm LED source.Main Results. Using chemometric data processing the classification of informative parameters has been performed and three most significant parameters have been chosen which account for 72% of total data variance. Testing has been done using SIMCA and k-NN methods. It has been proved that the use of the original and the reduced sets of three parameters produces comparable accuracy for classification of bioaerosols. Practical Relevance. The possibility of rapid detection and identification of bioaerosol particles of 1-10 microns respirable fraction (hindering in the human respiratory system by flow-optical method on a background of non-biological particles is demonstrated. The most informative optical spectral ranges for development of compact and inexpensive analyzer are chosen.
A FAST LAGRANGIAN SIMULATION METHOD FOR FLOW ANALYSIS AND RUNNER DESIGN IN PELTON TURBINES
Institute of Scientific and Technical Information of China (English)
ANAGNOSTOPOULOS John S.; PAPANTONIS Dimitris E.
2012-01-01
In the present work,an alternative numerical methodology is developed for a fast and effective simulation and analysis of the complex flow and energy conversion in Pelton impulse hydro turbines.The algorithm is based on the Lagrangian approach and the unsteady free-surface flow during the jet-bucket interaction is simulated by tracking the trajectories of representative fluid particles at very low computer cost.Modern regression tools are implemented in a new parameterization technique of the inner bucket surface.Key-feature of the model is the introduction of additional terms into the particle motion equations to account for various hydraulic losses and the flow spreading,which are regulated and evaluated with the aid of experimental data in a Laboratory Pelton turbine.The model is applied to study the jet-runner interaction in various operation conditions and then to perform numerical design optimization of the bucket shape,using a stochastic optimizer based on evolutionary algorithms.The obtained optimum runner attains remarkably higher hydraulic efficiency in the entire load range.Finally,a new small Pelton turbine (150 kW) is designed,manufactured and tested in the Laboratory,and its performance and efficiency verify the model predictions.
DEFF Research Database (Denmark)
Kamel, Salah; Jurado, Francisco; Chen, Zhe
2016-01-01
This study proposes the generalised unified power flow controller (GUPFC) model in the hybrid current power mismatch Newton-Raphson formulation (HPCIM). In this model, active power, real and imaginary current components are injected at the terminals of series impedances of GUPFC. These injected...... values are calculated during the iterative process based on the desired controlled values and buses voltage at the terminals of GUPFC. The parameters of GUPFC can be calculated during the iterative process and the final values are updated after load flow convergence. Using the developed GUPFC model......, the original structure and symmetry of the admittance and Jacobian matrices can still be kept, the changing of Jacobian matrix is eliminated. Consequently, the complexities of the computer load flow program codes with GUPFC are reduced. The HPCIM load flow code with the proposed model is written in C...
Barone, Mario; Lombardi, Simone; Continillo, Gaetano; Sementa, Paolo; Vaglieco, Bianca Maria
2016-12-01
This paper illustrates the analysis conducted on high-definition, high sampling rate image sequences collected in experiments with a single spark ignition optically accessible engine. Images are first processed to identify the reaction front, and then analyzed by an optical flow estimation technique. The results show that each velocity component of the estimated flow field has an ECDF very similar to the CDF of a Gaussian distribution, whereas the velocity magnitude has an ECDF well fitted by a Rayleigh probability distribution. The proposed non-intrusive method provides a fast statistical characterization of the flame propagation phenomenon in the engine combustion chamber.
Chen, Shu-cheng, S.
2009-01-01
For the preliminary design and the off-design performance analysis of axial flow turbines, a pair of intermediate level-of-fidelity computer codes, TD2-2 (design; reference 1) and AXOD (off-design; reference 2), are being evaluated for use in turbine design and performance prediction of the modern high performance aircraft engines. TD2-2 employs a streamline curvature method for design, while AXOD approaches the flow analysis with an equal radius-height domain decomposition strategy. Both methods resolve only the flows in the annulus region while modeling the impact introduced by the blade rows. The mathematical formulations and derivations involved in both methods are documented in references 3, 4 for TD2-2) and in reference 5 (for AXOD). The focus of this paper is to discuss the fundamental issues of applicability and compatibility of the two codes as a pair of companion pieces, to perform preliminary design and off-design analysis for modern aircraft engine turbines. Two validation cases for the design and the off-design prediction using TD2-2 and AXOD conducted on two existing high efficiency turbines, developed and tested in the NASA/GE Energy Efficient Engine (GE-E3) Program, the High Pressure Turbine (HPT; two stages, air cooled) and the Low Pressure Turbine (LPT; five stages, un-cooled), are provided in support of the analysis and discussion presented in this paper.
Advanced Methods for Aircraft Engine Thrust and Noise Benefits: Nozzle-Inlet Flow Analysis
Gilinsky, Mikhail; Morgan, Morris H.; Povitsky, Alex; Schkolnikov, Natalia; Njoroge, Norman; Coston, Calvin; Blankson, Isaiah M.
2001-01-01
The Fluid Mechanics and Acoustics Laboratory at Hampton University (HU/FM&AL) jointly with the NASA Glenn Research Center has conducted four connected subprojects under the reporting project. Basically, the HU/FM&AL Team has been involved in joint research with the purpose of theoretical explanation of experimental facts and creation of accurate numerical simulation techniques and prediction theory for solution of current problems in propulsion systems of interest to the NAVY and NASA agencies. This work is also supported by joint research between the NASA GRC and the Institute of Mechanics at Moscow State University (IM/MSU) in Russia under a CRDF grant. The research is focused on a wide regime of problems in the propulsion field as well as in experimental testing and theoretical and numerical simulation analyses for advanced aircraft and rocket engines. The FM&AL Team uses analytical methods, numerical simulations and possible experimental tests at the Hampton University campus. The fundamental idea uniting these subprojects is to use nontraditional 3D corrugated and composite nozzle and inlet designs and additional methods for exhaust jet noise reduction without essential thrust loss and even with thrust augmentation. These subprojects are: (1) Aeroperformance and acoustics of Bluebell-shaped and Telescope-shaped designs; (2) An analysis of sharp-edged nozzle exit designs for effective fuel injection into the flow stream in air-breathing engines: triangular-round, diamond-round and other nozzles; (3) Measurement technique improvement for the HU Low Speed Wind Tunnel; a new course in the field of aerodynamics, teaching and training of HU students; experimental tests of Mobius-shaped screws: research and training; (4) Supersonic inlet shape optimization. The main outcomes during this reporting period are: (l) Publications: The AIAA Paper #00-3170 was presented at the 36th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 17-19 June, 2000, Huntsville, AL. The AIAA
Wang, Shouyu; Jin, Ying; Yan, Keding; Xue, Liang; Liu, Fei; Li, Zhenhua
2014-11-01
Quantitative interferometric microscopy is used in biological and medical fields and a wealth of applications are proposed in order to detect different kinds of biological samples. Here, we develop a phase detecting cytometer based on quantitative interferometric microscopy with expanded principal component analysis phase retrieval method to obtain phase distributions of red blood cells with a spatial resolution ~1.5 μm. Since expanded principal component analysis method is a time-domain phase retrieval algorithm, it could avoid disadvantages of traditional frequency-domain algorithms. Additionally, the phase retrieval method realizes high-speed phase imaging from multiple microscopic interferograms captured by CCD camera when the biological cells are scanned in the field of view. We believe this method can be a powerful tool to quantitatively measure the phase distributions of different biological samples in biological and medical fields.
Abrahams, J R; Hiller, N
1965-01-01
Signal Flow Analysis provides information pertinent to the fundamental aspects of signal flow analysis. This book discusses the basic theory of signal flow graphs and shows their relation to the usual algebraic equations.Organized into seven chapters, this book begins with an overview of properties of a flow graph. This text then demonstrates how flow graphs can be applied to a wide range of electrical circuits that do not involve amplification. Other chapters deal with the parameters as well as circuit applications of transistors. This book discusses as well the variety of circuits using ther
Directory of Open Access Journals (Sweden)
Gunar Boye
2015-06-01
Full Text Available The axial heat transfer coefficient during flow boiling of n-hexane was measured using infrared thermography to determine the axial wall temperature in three geometrically similar annular gaps with different widths (s = 1.5 mm, s = 1 mm, s = 0.5 mm. During the design and evaluation process, the methods of statistical experimental design were applied. The following factors/parameters were varied: the heat flux q · = 30 − 190 kW / m 2 , the mass flux m · = 30 − 700 kg / m 2 s , the vapor quality x · = 0 . 2 − 0 . 7 , and the subcooled inlet temperature T U = 20 − 60 K . The test sections with gap widths of s = 1.5 mm and s = 1 mm had very similar heat transfer characteristics. The heat transfer coefficient increases significantly in the range of subcooled boiling, and after reaching a maximum at the transition to the saturated flow boiling, it drops almost monotonically with increasing vapor quality. With a gap width of 0.5 mm, however, the heat transfer coefficient in the range of saturated flow boiling first has a downward trend and then increases at higher vapor qualities. For each test section, two correlations between the heat transfer coefficient and the operating parameters have been created. The comparison also shows a clear trend of an increasing heat transfer coefficient with increasing heat flux for test sections s = 1.5 mm and s = 1.0 mm, but with increasing vapor quality, this trend is reversed for test section 0.5 mm.
Directory of Open Access Journals (Sweden)
Knight Chris
2017-01-01
Full Text Available Polydisperse granular materials are ubiquitous in nature and industry. Despite this, knowledge of the momentum coupling between the fluid and solid phases in dense saturated grain packings comes almost exclusively from empirical correlations [2–4, 8] with monosized media. The Immersed Boundary Method (IBM is a Computational Fluid Dynamics (CFD modelling technique capable of resolving pore scale fluid flow and fluid-particle interaction forces in polydisperse media at the grain scale. Validation of the IBM in the low Reynolds number, high concentration limit was performed by comparing simulations of flow through ordered arrays of spheres with the boundary integral results of Zick and Homsy [10]. Random grain packings were studied with linearly graded particle size distributions with a range of coefficient of uniformity values (Cu = 1.01, 1.50, and 2.00 at a range of concentrations (ϕ ∈ [0.396; 0.681] in order to investigate the influence of polydispersity on drag and permeability. The sensitivity of the IBM results to the choice of radius retraction parameter [1] was investigated and a comparison was made between the predicted forces and the widely used Ergun correlation [3].
The Cauchy-Lagrangian method for numerical analysis of Euler flow
Podvigina, O; Frisch, U
2015-01-01
A novel semi-Lagrangian method is introduced to solve numerically the Euler equation for ideal incompressible flow in arbitrary space dimension. It exploits the time-analyticity of fluid particle trajectories and requires, in principle, only limited spatial smoothness of the initial data. Efficient generation of high-order time-Taylor coefficients is made possible by simple recurrence relations that follow from the Cauchy invariants formulation of the Euler equations (Zheligovsky & Frisch, J. Fluid Mech. 2014, 749, 404-430). Truncated time-Taylor series of very high order allow the use of time steps vastly exceeding the Courant-Friedrichs-Lewy limit, without compromising the accuracy of the solution. Tests performed on the two-dimensional Euler equation indicate that the Cauchy-Lagrangian method is more --- and occasionally much more --- efficient and less prone to instability than Eulerian Runge-Kutta methods and less prone to rapid growth of rounding errors than the high-order Eulerian time-Taylor algor...
Flux-splitting finite volume method for turbine flow and heat transfer analysis
Xu, C.; Amano, R. S.
A novel numerical method was developed to deal with the flow and heat transfer in a turbine cascade at both design and off-design conditions. The Navier-Stokes equations are discretized and integrated in a coupled manner. In the present method a time-marching scheme was employed along with the time-integration approach. The flux terms are discretized based on a cell finite volume formulation as well as a flux-difference splitting. The flux-difference splitting makes the scheme rapid convergence and the finite volume technique ensure the governing equations for the conservation of mass, momentum and energy. A hybrid difference scheme for quasi-three-dimensional procedure based on the discretized and integrated Navier-Stokes equations was incorporated in the code. The numerical method possesses the positive features of the explicit and implicit algorithms which provide a rapid convergence process and have a less stability constraint. The computed results were compared with other numerical studies and experimental data. The comparisons showed fairly good agreement with experiments.
FLOW-Methode - Methodenbeschreibung zur Anwendung von FLOW
Stapel, Kai
2012-01-01
Information of many kinds is flowing in software projects and organizations. Requirements have to flow from the customer to the developers. Testers need to know the requirements as well. Boundary conditions and design decisions have to be at the right place at the right time. Information flow analysis with FLOW facilitates modeling of mode and route of the flow of information and experience independent of the development methodology. Experience often acts as a control factor, because experienced developers can process and route information more efficiently. Therefore, experience needs to be at the right place at the right time, too. However, most valuable experiences never get documented. Since information and experience is flowing in agile as well as in traditional environments, the FLOW method does not distinguish between agile and traditional, but only between how the flows are shaped. ---- In Softwareprojekten flie{\\ss}en vielerlei Informationen. Anforderungen m\\"ussen vom Kunden zu den Entwicklern gelang...
Deformation analysis of 3D tagged cardiac images using an optical flow method
Directory of Open Access Journals (Sweden)
Gorman Robert C
2010-03-01
Full Text Available Abstract Background This study proposes and validates a method of measuring 3D strain in myocardium using a 3D Cardiovascular Magnetic Resonance (CMR tissue-tagging sequence and a 3D optical flow method (OFM. Methods Initially, a 3D tag MR sequence was developed and the parameters of the sequence and 3D OFM were optimized using phantom images with simulated deformation. This method then was validated in-vivo and utilized to quantify normal sheep left ventricular functions. Results Optimizing imaging and OFM parameters in the phantom study produced sub-pixel root-mean square error (RMS between the estimated and known displacements in the x (RMSx = 0.62 pixels (0.43 mm, y (RMSy = 0.64 pixels (0.45 mm and z (RMSz = 0.68 pixels (1 mm direction, respectively. In-vivo validation demonstrated excellent correlation between the displacement measured by manually tracking tag intersections and that generated by 3D OFM (R ≥ 0.98. Technique performance was maintained even with 20% Gaussian noise added to the phantom images. Furthermore, 3D tracking of 3D cardiac motions resulted in a 51% decrease in in-plane tracking error as compared to 2D tracking. The in-vivo function studies showed that maximum wall thickening was greatest in the lateral wall, and increased from both apex and base towards the mid-ventricular region. Regional deformation patterns are in agreement with previous studies on LV function. Conclusion A novel method was developed to measure 3D LV wall deformation rapidly with high in-plane and through-plane resolution from one 3D cine acquisition.
Continuous flow analysis method for determination of soluble iron and aluminium in ice cores.
Spolaor, A; Vallelonga, P; Gabrieli, J; Roman, M; Barbante, C
2013-01-01
Iron and aluminium are the two most abundant metals on the Earth's crust, but they display quite different biogeochemical properties. While iron is essential to many biological processes, aluminium has not been found to have any biological function at all. In environmental studies, iron has been studied in detail for its limiting role in the bioproductivity of high nutrient, low carbon oceanic zones, while aluminium is routinely used as a reference of crustal contributions to atmospheric deposition archives including peat bogs, lacustrine and marine sediments and ice sheets and glaciers. We report here the development of a flow injection analysis technique, which has been optimised for the simultaneous determination of soluble iron and aluminium in polar ice cores. Iron was determined by its catalytic role in the reduction of N,N-dimethyl-p-phenylenediamene (DPD) to a semiquinonic form (DPDQ) and subsequent absorption spectroscopy at 514 nm. Aluminium was determined by spectroscopic analysis of an aluminium-lumogallion complex that exhibits fluorescence at 560 nm. These techniques have been applied to a section of Greenland ice dated to 1729-1733 AD and indicate that volcanism is a source of highly soluble aluminium and iron.
A control-volume method for analysis of unsteady thrust augmenting ejector flows
Drummond, Colin K.
1988-01-01
A method for predicting transient thrust augmenting ejector characteristics is presented. The analysis blends classic self-similar turbulent jet descriptions with a control volume mixing region discretization to solicit transient effects in a new way. Division of the ejector into an inlet, diffuser, and mixing region corresponds with the assumption of viscous-dominated phenomenon in the latter. Inlet and diffuser analyses are simplified by a quasi-steady analysis, justified by the assumptions that pressure is the forcing function in those regions. Details of the theoretical foundation, the solution algorithm, and sample calculations are given.
Martins, Elisandra C; Melo, Vander De F; Abate, Gilberto
2016-09-01
A method for determining atrazine in soil extracts was evaluated by flow injection analysis with spectrophotometric detection. The method is based on the reaction of atrazine with pyridine in an acid medium followed by the reaction with NaOH and sulfanilic acid. Several analytical conditions were previously studied and optimized. Under the best conditions of analysis, the limits of detection and quantification were 0.15 and 0.45 mg L(-1), respectively, for a linear response between 0.50 and 2.50 mg L(-1), and a sampling throughput of 21 determinations per hour. Using the standard addition method, the maximum relative standard deviation of 17% and recovery values between 80 and 100% were observed for three extracts from soil samples with different composition. The proposed method is simple, low-cost and easy to use, and can be employed for studies involving atrazine in soil samples or for screening of atrazine in soils.
Li, Z. K.
1985-01-01
A specialized program was developed for flow cytometric list-mode data using an heirarchical tree method for identifying and enumerating individual subpopulations, the method of principal components for a two-dimensional display of 6-parameter data array, and a standard sorting algorithm for characterizing subpopulations. The program was tested against a published data set subjected to cluster analysis and experimental data sets from controlled flow cytometry experiments using a Coulter Electronics EPICS V Cell Sorter. A version of the program in compiled BASIC is usable on a 16-bit microcomputer with the MS-DOS operating system. It is specialized for 6 parameters and up to 20,000 cells. Its two-dimensional display of Euclidean distances reveals clusters clearly, as does its 1-dimensional display. The identified subpopulations can, in suitable experiments, be related to functional subpopulations of cells.
Effect of flow fluctuations and nonflow on elliptic flow methods
Energy Technology Data Exchange (ETDEWEB)
Ollitrault, Jean-Yves; Poskanzer, Arthur M.; Voloshin, Sergei A.
2009-04-16
We discuss how the different estimates of elliptic flow are influenced by flow fluctuations and nonflow effects. It is explained why the event-plane method yields estimates between the two-particle correlation methods and the multiparticle correlation methods. It is argued that nonflow effects and fluctuations cannot be disentangled without other assumptions. However, we provide equations where, with reasonable assumptions about fluctuations and nonflow, all measured values of elliptic flow converge to a unique mean v_2,PP elliptic flow in the participant plane and, with a Gaussian assumption on eccentricity fluctuations, can be converted to the mean v_2,RP in the reaction plane. Thus, the 20percent spread in observed elliptic flow measurements from different analysis methods is no longer mysterious.
Directory of Open Access Journals (Sweden)
López-Carro Beatriz
2009-01-01
Full Text Available Abstract Homogeneity of cell populations is a prerequisite for the analysis of biochemical and molecular events during male gamete differentiation. Given the complex organization of the mammalian testicular tissue, various methods have been used to obtain enriched or purified cell populations, including flow cell sorting. Current protocols are usually time-consuming and may imply loss of short-lived RNAs, which is undesirable for expression profiling. We describe an optimized method to speed up the preparation of suitable testicular cell suspensions for cytometric analysis of different spermatogenic stages from rodents. The procedure takes only 15 min including testis dissection, tissue cutting, and processing through the Medimachine System (Becton Dickinson. This method could be a substitute for the more tedious and time-consuming cell preparation techniques currently in use.
Directory of Open Access Journals (Sweden)
Rodríguez-Casuriaga Rosana
2009-03-01
Full Text Available Abstract Homogeneity of cell populations is a prerequisite for the analysis of biochemical and molecular events during male gamete differentiation. Given the complex organization of the mammalian testicular tissue, various methods have been used to obtain enriched or purified cell populations, including flow cell sorting. Current protocols are usually time-consuming and may imply loss of short-lived RNAs, which is undesirable for expression profiling. We describe an optimized method to speed up the preparation of suitable testicular cell suspensions for cytometric analysis of different spermatogenic stages from rodents. The procedure takes only 15 min including testis dissection, tissue cutting, and processing through the Medimachine System (Becton Dickinson. This method could be a substitute for the more tedious and time-consuming cell preparation techniques currently in use.
Belfort, Benjamin; Weill, Sylvain; Lehmann, François
2017-07-01
A novel, non-invasive imaging technique is proposed that determines 2D maps of water content in unsaturated porous media. This method directly relates digitally measured intensities to the water content of the porous medium. This method requires the classical image analysis steps, i.e., normalization, filtering, background subtraction, scaling and calibration. The main advantages of this approach are that no calibration experiment is needed, because calibration curve relating water content and reflected light intensities is established during the main monitoring phase of each experiment and that no tracer or dye is injected into the flow tank. The procedure enables effective processing of a large number of photographs and thus produces 2D water content maps at high temporal resolution. A drainage/imbibition experiment in a 2D flow tank with inner dimensions of 40 cm × 14 cm × 6 cm (L × W × D) is carried out to validate the methodology. The accuracy of the proposed approach is assessed using a statistical framework to perform an error analysis and numerical simulations with a state-of-the-art computational code that solves the Richards' equation. Comparison of the cumulative mass leaving and entering the flow tank and water content maps produced by the photographic measurement technique and the numerical simulations demonstrate the efficiency and high accuracy of the proposed method for investigating vadose zone flow processes. Finally, the photometric procedure has been developed expressly for its extension to heterogeneous media. Other processes may be investigated through different laboratory experiments which will serve as benchmark for numerical codes validation.
analysis of flow in a concentric annulus using finite element method
African Journals Online (AJOL)
user
ABSTRACT. This work presents the computational modelling of the velocity distribution of an incompressible fluid flowing in a ... concentric annulus with center body rotation. [9] used .... pipe at a glance with a very high accuracy compared to.
Directory of Open Access Journals (Sweden)
Dinarvand Saeed
2015-01-01
Full Text Available This article deals with the study of the steady axisymmetric mixed convective boundary layer flow of a nanofluid over a vertical circular cylinder with prescribed external flow and surface temperature. By means of similarity transformation, the governing partial differential equations are reduced into highly non-linear ordinary differential equations. The resulting non-linear system has been solved analytically using an efficient technique namely homotopy analysis method (HAM. Expressions for velocity and temperature fields are developed in series form. In this study, three different types of nanoparticles are considered, namely alumina (, titania (, and copper ( with water as the base fluid. For copper-water nanofluid, graphical results are presented to describe the influence of the nanoparticle volume fraction on the velocity and temperature fields for the forced and mixed convection flows. Moreover, the features of the flow and heat transfer characteristics are analyzed and discussed for foregoing nanofluids. It is found that the skin friction coefficient and the heat transfer rate at the surface are highest for copper-water nanofluid compared to the alumina-water and titania-water nanofluids.
Krýza, Ondřej; Lexa, Ondrej; Závada, Prokop; Schulmann, Karel; Gapais, Denis; Cosgrove, John
2017-04-01
Recently, a PIV (particle image velocimetry) analysis method is optical method abundantly used in many technical branches where material flow visualization and quantification is important. Typical examples are studies of liquid flow through complex channel system, gas spreading or combustion problematics. In our current research we used this method for investigation of two types of complex analogue geodynamic and tectonic experiments. First class of experiments is aimed to model large-scale oroclinal buckling as an analogue of late Paleozoic to early Mesozoic evolution of Central Asian Orogenic Belt (CAOB) resulting from nortward drift of the North-China craton towards the Siberian craton. Here we studied relationship between lower crustal and lithospheric mantle flows and upper crustal deformation respectively. A second class of experiments is focused to more general study of a lower crustal flow in indentation systems that represent a major component of some large hot orogens (e.g. Bohemian massif). The most of simulations in both cases shows a strong dependency of a brittle structures shape, that are situated in upper crust, on folding style of a middle and lower ductile layers which is influenced by rheological, geometrical and thermal conditions of different parts across shortened domain. The purpose of PIV application is to quantify material redistribution in critical domains of the model. The derivation of flow direction and calculation of strain-rate and total displacement field in analogue experiments is generally difficult and time-expensive or often performed only on a base of visual evaluations. PIV method operates with set of images, where small tracer particles are seeded within modeled domain and are assumed to faithfully follow the material flow. On base of pixel coordinates estimation the material displacement field, velocity field, strain-rate, vorticity, tortuosity etc. are calculated. In our experiments we used velocity field divergence to
DEFF Research Database (Denmark)
Momeni, M.; Jamshidi, N.; Barari, Amin
2011-01-01
Purpose - In this paper a study of the flow and heat transfer of an incompressible homogeneous second grade fluid past a stretching sheet channel is presented and the Homotopy Analysis Method (HAM) is employed to compute an approximation to the solution of the system of nonlinear differential...... equations governing on the problem. It has been attempted to show the capabilities and wide-range applications of the Homotopy Analysis Method in comparison with the numerical method in solving this problems. The obtained solutions, in comparison with the exact solutions admit a remarkable accuracy. A clear...... conclusion can be drawn from the numerical method results that the HAM provides highly accurate solutions for nonlinear differential equations. Design/methodology/approach - In this paper a study of the flow and heat transfer of an incompressible homogeneous second grade fluid past a stretching sheet channel...
Numerical methods for turbulent flow
Turner, James C., Jr.
1988-01-01
It has generally become accepted that the Navier-Strokes equations predict the dynamic behavior of turbulent as well as laminar flows of a fluid at a point in space away form a discontinuity such as a shock wave. Turbulence is also closely related to the phenomena of non-uniqueness of solutions of the Navier-Strokes equations. These second order, nonlinear partial differential equations can be solved analytically for only a few simple flows. Turbulent flow fields are much to complex to lend themselves to these few analytical methods. Numerical methods, therefore, offer the only possibility of achieving a solution of turbulent flow equations. In spite of recent advances in computer technology, the direct solution, by discrete methods, of the Navier-Strokes equations for turbulent flow fields is today, and in the foreseeable future, impossible. Thus the only economically feasible way to solve practical turbulent flow problems numerically is to use statistically averaged equations governing mean-flow quantities. The objective is to study some recent developments relating to the use of numerical methods to study turbulent flow.
Directory of Open Access Journals (Sweden)
Chuzlov Vjacheslav
2016-01-01
Full Text Available An approach to simulation of hydrocarbons refining processes catalytic reactors. The kinetic and thermodynamic research of light naphtha isomerization process was conducted. The kinetic parameters of hydrocarbon feedstock chemical conversion on different types of platinum-content catalysts was established. The estimation of efficiency of including different types of isomerization technologies in oil refinery flow diagram was performed.
Wang, Lutao; Xiao, Jun; Chai, Hua
2015-08-01
The successful suppression of clutter arising from stationary or slowly moving tissue is one of the key issues in medical ultrasound color blood imaging. Remaining clutter may cause bias in the mean blood frequency estimation and results in a potentially misleading description of blood-flow. In this paper, based on the principle of general wall-filter, the design process of three classes of filters, infinitely impulse response with projection initialization (Prj-IIR), polynomials regression (Pol-Reg), and eigen-based filters are previewed and analyzed. The performance of the filters was assessed by calculating the bias and variance of a mean blood velocity using a standard autocorrelation estimator. Simulation results show that the performance of Pol-Reg filter is similar to Prj-IIR filters. Both of them can offer accurate estimation of mean blood flow speed under steady clutter conditions, and the clutter rejection ability can be enhanced by increasing the ensemble size of Doppler vector. Eigen-based filters can effectively remove the non-stationary clutter component, and further improve the estimation accuracy for low speed blood flow signals. There is also no significant increase in computation complexity for eigen-based filters when the ensemble size is less than 10.
Curran, Christopher A.; Eng, Ken; Konrad, Christopher P.
2012-01-01
A regional low-flow survey of small, perennial streams in western Washington was initiated by the Northwest Indian Fisheries Commission (NWIFC), NWIFC-member tribes, and Point-No-Point Treaty Council in cooperation with the U.S. Geological Survey in 2007 and repeated by the tribes during the low-flow seasons of 2008–09. Low-flow measurements at 63 partial-record and miscellaneous streamflow-measurement sites during surveys in 2007–09 are used with concurrent flows at continuous streamflow-gaging stations (index sites) within the U.S. Geological Survey network to estimate the low-flow metric Q7,10 at each measurement site (Q7,10 is defined as the lowest average streamflow for a consecutive 7-day period that recurs on average once every 10 years). Index-site correlation methods for estimating low-flow characteristics at partial-record sites are reviewed and an empirical Monte Carlo technique is used with the daily streamflow record at 43 index sites to determine the error and bias associated with estimating the Q7,10 at synthetic partial-record sites using three methods: Q-ratio, MOVE.1, and Base-Flow Correlation. The Q-ratio method generally has the lowest error and least amount of bias for 170 scenarios, with each scenario defined by the number of concurrent flow measurements between the partial-record and index sites (ranging from 4 to 20) and the combination of basin attributes used to select the index site. The root-mean square error for the Q-ratio method ranged from 70 to 118 percent, depending on the scenario. The scenario with the smallest root-mean square error used four concurrent flow measurements and the basin attributes: basin area, mean annual precipitation, and base-flow recession time constant, also referred to as tau (τ).
DEFF Research Database (Denmark)
Jabbaribehnam, Mirmasoud; Bulatova, Regina; Tok, A. I Y
2016-01-01
fluid flow analysis of tape casting. In the present paper a review of the development of the tape casting process with particular focus on the rheological classifications as well as modelling the material flow is hence presented and in this context the current status is examined and future potential...
Directory of Open Access Journals (Sweden)
G. Domairry
2009-01-01
Full Text Available An analysis has been performed to study magneto-hydrodynamic (MHD squeeze flow between two parallel infinite disks where one disk is impermeable and the other is porous with either suction or injection of the fluid. We investigate the combined effect of inertia, electromagnetic forces, and suction or injection. With the introduction of a similarity transformation, the continuity and momentum equations governing the squeeze flow are reduced to a single, nonlinear, ordinary differential equation. An approximate solution of the equation subject to the appropriate boundary conditions is derived using the homotopy perturbation method (HPM and compared with the direct numerical solution (NS. Results showing the effect of squeeze Reynolds number, Hartmann number and the suction/injection parameter on the axial and radial velocity distributions are presented and discussed. The approximate solution is found to be highly accurate for the ranges of parameters investigated. Because of its simplicity, versatility and high accuracy, the method can be applied to study linear and nonlinear boundary value problems arising in other engineering applications.
Rakhmanov, Vitaly V.; Kulikov, Dmitry V.
2014-08-01
Possibility of use of a refractive-index-matching method for flow investigation by LDA method in models of the fire chambers of complex geometry is shown. The technique of flows investigation by LDA method is developed. The given technique can be successfully applied in leading branches of a thermal and hydropower engineering, in case of need of flows diagnostics in models of devices with the complex geometry.
Benussi, G; Canciani, G P; de Luyk, S; Parco, S; Visconti, P; Grandolfo, M; Mangiarotti, M A
1984-03-01
The authors describe the application of a technique called Patient Flow Analysis aimed at the improvement of Clinic Personnel efficiency and reduction of patient waiting time. Results were satisfactory and encourage further experiences.
Nabwey, Hossam A.; Boumazgour, Mohamed; Rashad, A. M.
2017-03-01
The group method analysis is applied to study the steady mixed convection stagnation-point flow of a non-Newtonian nanofluid towards a vertical stretching surface. The model utilized for the nanofluid incorporates the Brownian motion and thermophoresis effects. Applying the one-parameter transformation group which reduces the number of independent variables by one and thus, the system of governing partial differential equations has been converted to a set of nonlinear ordinary differential equations, and these equations are then computed numerically using the implicit finite-difference scheme. Comparison with previously published studies is executed and the results are found to be in excellent agreement. Results for the velocity, temperature, and the nanoparticle volume fraction profiles as well as the local skin-friction coefficient and local Nusselt number are presented in graphical and tabular forms, and discussed for different values of the governing parameters to show interesting features of the solutions.
Continuous flow analysis method for determination of dissolved reactive phosphorus in ice cores.
Kjær, Helle Astrid; Vallelonga, Paul; Svensson, Anders; Kristensen, Magnus Elleskov L; Tibuleac, Catalin; Bigler, Matthias
2013-01-01
Phosphorus (P) is an essential macronutrient for all living organisms. Phosphorus is often present in nature as the soluble phosphate ion PO4(3-) and has biological, terrestrial, and marine emission sources. Thus PO4(3-) detected in ice cores has the potential to be an important tracer for biological activity in the past. In this study a continuous and highly sensitive absorption method for detection of dissolved reactive phosphorus (DRP) in ice cores has been developed using a molybdate reagent and a 2-m liquid waveguide capillary cell (LWCC). DRP is the soluble form of the nutrient phosphorus, which reacts with molybdate. The method was optimized to meet the low concentrations of DRP in Greenland ice, with a depth resolution of approximately 2 cm and an analytical uncertainty of 1.1 nM (0.1 ppb) PO4(3-). The method has been applied to segments of a shallow firn core from Northeast Greenland, indicating a mean concentration level of 2.74 nM (0.26 ppb) PO4(3-) for the period 1930-2005 with a standard deviation of 1.37 nM (0.13 ppb) PO4(3-) and values reaching as high as 10.52 nM (1 ppb) PO4(3-). Similar levels were detected for the period 1771-1823. Based on impurity abundances, dust and biogenic particles were found to be the most likely sources of DRP deposited in Northeast Greenland.
Acosta, Gimena; Talio, María C; Luconi, Marta O; Hinze, Willie L; Fernández, Liliana P
2014-11-01
An on-line surfactant mediated extraction method in a flow injection analysis format with fluorescence detection was developed for the determination of Rhodamine B (RhB) in food condiments. The sample was extracted using the phase separation behavior exhibited by the bile salt surfactant, sodium cholate (NaC), upon addition of sodium dodecylsulfate (SDS) in the presence of acid at room temperature. The RhB in the sample was incorporated into the NaC/SDS coacervate phase which was then collected on a glass-wool packed mini column from which it was subsequently eluted using a 1.00 mol L(-1) HCl solution. The inherent fluorescence (λex=555 nm; λem=575 nm) of RhB was employed for detection. Good linearity (r(2)=0.9933) was obtained over the concentration range 0.4-4794-479.0 µg L(-1) RhB. The detection (LOD) and quantification (LOQ) limits were 0.12 and 0.40 µg L(-1), respectively. The method was successfully applied for analysis of RhB in food condiments and spiked samples. The average recoveries ranged from 95.3% to 118.9% at spiked concentration levels of 1.19 and 2.39 µg L(-1). Under optimized conditions, a throughput of 50 samples per hour was achieved. The proposed method may be a valuable tool not only for quality control of food condiments and similar food confectioneries but for the analysis of a variety of other RhB-containing samples as well.
DEFF Research Database (Denmark)
Hansen, Elo Harald
2004-01-01
This chapter provides an introduction to automated chemical analysis, which essentially can be divided into two groups: batch assays, where the solution is stationary while the container is moved through a number of stations where various unit operations performed; and continuous-flow procedures,......, but it permits thr execution of novel and unique analytical procedures which are difficult or even impossible by conventional means. The performance and applicability of FIA, SI and LOV are illustrated by a series of practical examples.......This chapter provides an introduction to automated chemical analysis, which essentially can be divided into two groups: batch assays, where the solution is stationary while the container is moved through a number of stations where various unit operations performed; and continuous-flow procedures......, where the system is stationary while the solution moves through a set of conduits in which all required manipulations are performed. Emphasis is placed on flow injection analysis (FIA) and its further developments, that is, sequential injection analysis (SIA) and the Lab-on-Valve (LOV) approach. Since...
Directory of Open Access Journals (Sweden)
Jenny Greberg
2016-06-01
Full Text Available As the near surface deposits are being mined out, underground mines will increasingly operate at greater depths. This will increase the challenges related to transporting materials from deeper levels to the surface. For many years, the ore and waste transportation from most deep underground mines has depended on some or all of the following: truck haulage, conveyor belts, shafts, rails, and ore pass systems. In sub-level caving, and where ore passes are used, trains operating on the main lower level transport the ore from ore passes to a crusher, for subsequent hoisting to the surface through the shaft system. In many mines, the use of the ore pass system has led to several problems related to the ore pass availability, causing production disturbances and incurred cost and time for ore pass rehabilitation. These production disturbances have an impact on the mining activities since they increase the operational costs, and lower the mine throughput. A continued dependency on rock mass transportation using ore passes will generate high capital costs for various supporting structures such as rail tracks, shaft extensions, and crushers for every new main level. This study was conducted at an existing underground mine and analyzed the transport of ore from loading areas at the lower levels up to the existing shaft points using trucks without employing ore passes. The results show that, when the costs of extending ore passes to lower levels become too great or ore passes cannot be used for production, haul trucks can be a feasible alternative method for transport of ore and waste up the ramp to the existing crusher located at the previous main level. The use of trucks will avoid installing infrastructure at the next main level and extending the ore passes to lower levels, hence reducing costs.
Niu, X. D.; Shu, C.; Chew, Y. T.
A Lattice Boltzmann model for simulating micro flows has been proposed by us recently (Europhysics Letters, 67(4), 600-606 (2004)). In this paper, we will present a further theoretical and numerical validation of the model. In this regards, a theoretical analysis of the diffuse-scattering boundary condition for a simple flow is carried out and the result is consistent with the conventional slip velocity boundary condition. Numerical validation is highlighted by simulating the two-dimensional isothermal pressure-driven micro-channel flows and the thin-film gas bearing lubrication problems, and comparing the simulation results with available experimental data and analytical predictions.
2007-11-02
S) AND ADDRESS(ES) DCW Industries, Inc. 5354 Palm Drive La Canada, CA 91011 8. PERFORMING ORGANIZATION...REPORT NUMBER DCW -38-R-05 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) U. S. Army Research Office...Turbulence Modeling for CFD, Second Edition, DCW Industries, Inc., La Cañada, CA. Wilcox, D. C. (2001), “Projectile Base Flow Analysis,” DCW
2009-01-01
Objective: In this paper we compared the two methods of cell sorting (magnetic cell sorting and flow cytometry sorting) for the isolation and function analysis of mouse CD4+ CD25+ regulatory T (Treg) cells, in order to inform further studies in Treg cell function. Methods: We separately used magnetic cell sorting and flow cytometry sorting to identify CD4+ CD25+ Treg cells. After magnetic cell separation, we further used flow cytometry to analyze the purity of CD4+ CD25+ Treg cells, trypan bl...
Modular Control Flow Analysis for Libraries
DEFF Research Database (Denmark)
Probst, Christian W.
2002-01-01
One problem in analyzing object oriented languages is that the exact control flow graph is not known statically due to dynamic dispatching. However, this is needed in order to apply the large class of known interprocedural analysis. Control Flow Analysis in the object oriented setting aims at det...... at determining run-time types of variables, thus allowing to possibly targeted method implementations. We present a flow sensitive analysis that allows separate handling of libraries and thereby efficient analysis of whole programs....
Carlson, Harry W.; Darden, Christine M.
1987-01-01
Low-speed experimental force and data on a series of thin swept wings with sharp leading edges and leading and trailing-edge flaps are compared with predictions made using a linearized-theory method which includes estimates of vortex forces. These comparisons were made to assess the effectiveness of linearized-theory methods for use in the design and analysis of flap systems in subsonic flow. Results demonstrate that linearized-theory, attached-flow methods (with approximate representation of vortex forces) can form the basis of a rational system for flap design and analysis. Even attached-flow methods that do not take vortex forces into account can be used for the selection of optimized flap-system geometry, but design-point performance levels tend to be underestimated unless vortex forces are included. Illustrative examples of the use of these methods in the design of efficient low-speed flap systems are included.
Directory of Open Access Journals (Sweden)
Yahaya Shagaiya Daniel
2015-09-01
Full Text Available This paper investigates the theoretical influence of buoyancy and thermal radiation on MHD flow over a stretching porous sheet. The model which constituted highly nonlinear governing equations is transformed using similarity solution and then solved using homotopy analysis method (HAM. The analysis is carried out up to the 5th order of approximation and the influences of different physical parameters such as Prandtl number, Grashof number, suction/injection parameter, thermal radiation parameter and heat generation/absorption coefficient and also Hartman number on dimensionless velocity, temperature and the rate of heat transfer are investigated and discussed quantitatively with the aid of graphs. Numerical results obtained are compared with the previous results published in the literature and are found to be in good agreement. It was found that when the buoyancy parameter and the fluid velocity increase, the thermal boundary layer decreases. In case of the thermal radiation, increasing the thermal radiation parameter produces significant increases in the thermal conditions of the fluid temperature which cause more fluid in the boundary layer due to buoyancy effect, causing the velocity in the fluid to increase. The hydrodynamic boundary layer and thermal boundary layer thickness increase as a result of increase in radiation.
Directory of Open Access Journals (Sweden)
Yun Seok Choi
2014-01-01
Full Text Available This work develops a grid based rainfall-runoff model (GRM, which is a physically based and spatially distributed model. Surface flow was analyzed using a kinematic wave model with the governing equations discretized using the finite volume method (FVM. This paper suggests a grid network flow analysis technique using variable rainfall intensity according to the flow directions to analyze one-dimensional flows between the grids. The model was evaluated by applying it to the Wuicheon watershed, a tributary of the Nakdonggang (Riv., in Korea. The results showed that the grid-based, one-dimensional kinematic wave model adopted the FVM and the grid network flow analysis technique well. The simulation results showed good agreement with the observed hydrographs and the initial soil saturation ratio was most sensitive to the modeling results.
Schüpbach, Simon; Federer, Urs; Kaufmann, Patrik R; Hutterli, Manuel A; Buiron, Daphné; Blunier, Thomas; Fischer, Hubertus; Stocker, Thomas F
2009-07-15
Methane (CH4) is the second most important anthropogenic greenhouse gas in the atmosphere. Rapid variations of the CH4 concentration, as frequently registered, for example, during the last ice age, have been used as reliable time markers for the definition of a common time scale of polar ice cores. In addition, these variations indicate changes in the sources of methane primarily associated with the presence of wetlands. In order to determine the exact time evolution of such fast concentration changes, CH4 measurements of the highest resolution in the ice core archive are required. Here, we present a new, semicontinuous and field-deployable CH4 detection method, which was incorporated in a continuous flow analysis (CFA) system. In CFA, samples cut along the axis of an ice core are melted at a melt speed of typically 3.5 cm/min. The air from bubbles in the ice core is extracted continuously from the meltwater and forwarded to a gas chromatograph (GC) for high-resolution CH4 measurements. The GC performs a measurement every 3.5 min, hence, a depth resolution of 15 cm is achieved atthe chosen melt rate. An even higher resolution is not necessary due to the low pass filtering of air in ice cores caused by the slow bubble enclosure process and the diffusion of air in firn. Reproducibility of the new method is 3%, thus, for a typical CH4 concentration of 500 ppb during an ice age, this corresponds to an absolute precision of 15 ppb, comparable to traditional analyses on discrete samples. Results of CFA-CH4 measurements on the ice core from Talos Dome (Antarctica) illustrate the much higher temporal resolution of our method compared with established melt-refreeze CH4 measurements and demonstrate the feasibility of the new method.
Kou, Jisheng
2013-06-20
We analyze a combined method consisting of the mixed finite element method for pressure equation and the discontinuous Galerkin method for saturation equation for the coupled system of incompressible two-phase flow in porous media. The existence and uniqueness of numerical solutions are established under proper conditions by using a constructive approach. Optimal error estimates in L2(H1) for saturation and in L∞(H(div)) for velocity are derived. Copyright © 2013 John Wiley & Sons, Ltd.
Anderson, O. L.; Briley, W. R.; Mcdonald, H.
1978-01-01
An approximate analysis is presented for calculating three-dimensional, low Mach number, laminar viscous flows in curved passages with large secondary flows and corner boundary layers. The analysis is based on the decomposition of the overall velocity field into inviscid and viscous components with the overall velocity being determined from superposition. An incompressible vorticity transport equation is used to estimate inviscid secondary flow velocities to be used as corrections to the potential flow velocity field. A parabolized streamwise momentum equation coupled to an adiabatic energy equation and global continuity equation is used to obtain an approximate viscous correction to the pressure and longitudinal velocity fields. A collateral flow assumption is invoked to estimate the viscous correction to the transverse velocity fields. The approximate analysis is solved numerically using an implicit ADI solution for the viscous pressure and velocity fields. An iterative ADI procedure is used to solve for the inviscid secondary vorticity and velocity fields. This method was applied to computing the flow within a turbine vane passage with inlet flow conditions of M = 0.1 and M = 0.25, Re = 1000 and adiabatic walls, and for a constant radius curved rectangular duct with R/D = 12 and 14 and with inlet flow conditions of M = 0.1, Re = 1000, and adiabatic walls.
Energy Technology Data Exchange (ETDEWEB)
Mesquita, Raquel B.R. [CBQF/Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, R. Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Laboratory of Hydrobiology, Institute of Biomedical Sciences Abel Salazar (ICBAS) and Institute of Marine Research (CIIMAR), Universidade do Porto, Lg. Abel Salazar 2, 4099-003 Porto (Portugal); Ferreira, M. Teresa S.O.B. [CBQF/Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, R. Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal); Toth, Ildiko V. [REQUIMTE, Departamento de Quimica, Faculdade de Farmacia, Universidade de Porto, Rua Anibal Cunha, 164, 4050-047 Porto (Portugal); Bordalo, Adriano A. [Laboratory of Hydrobiology, Institute of Biomedical Sciences Abel Salazar (ICBAS) and Institute of Marine Research (CIIMAR), Universidade do Porto, Lg. Abel Salazar 2, 4099-003 Porto (Portugal); McKelvie, Ian D. [School of Chemistry, University of Melbourne, Victoria 3010 (Australia); Rangel, Antonio O.S.S., E-mail: aorangel@esb.ucp.pt [CBQF/Escola Superior de Biotecnologia, Universidade Catolica Portuguesa, R. Dr. Antonio Bernardino de Almeida, 4200-072 Porto (Portugal)
2011-09-02
Highlights: {yields} Sequential injection determination of phosphate in estuarine and freshwaters. {yields} Alternative spectrophotometric flow cells are compared. {yields} Minimization of schlieren effect was assessed. {yields} Proposed method can cope with wide salinity ranges. {yields} Multi-reflective cell shows clear advantages. - Abstract: A sequential injection system with dual analytical line was developed and applied in the comparison of two different detection systems viz; a conventional spectrophotometer with a commercial flow cell, and a multi-reflective flow cell coupled with a photometric detector under the same experimental conditions. The study was based on the spectrophotometric determination of phosphate using the molybdenum-blue chemistry. The two alternative flow cells were compared in terms of their response to variation of sample salinity, susceptibility to interferences and to refractive index changes. The developed method was applied to the determination of phosphate in natural waters (estuarine, river, well and ground waters). The achieved detection limit (0.007 {mu}M PO{sub 4}{sup 3-}) is consistent with the requirement of the target water samples, and a wide quantification range (0.024-9.5 {mu}M) was achieved using both detection systems.
M.O. de Jong (Marg); H. Rozemuller (Henk); J.G.J. Bauman (J. G J); J.W.M. Visser (Jan)
1995-01-01
textabstractThe main prerequisites for the use of biotinylated ligands to study the expression of growth factor receptors on heterogeneous cell populations, such as peripheral blood or bone marrow, by flow cytometric methods, are that the biotinylated ligand retains its binding ability and that bind
M.O. de Jong (Marg); H. Rozemuller (Henk); J.G.J. Bauman (J. G J); J.W.M. Visser (Jan)
1995-01-01
textabstractThe main prerequisites for the use of biotinylated ligands to study the expression of growth factor receptors on heterogeneous cell populations, such as peripheral blood or bone marrow, by flow cytometric methods, are that the biotinylated ligand retains its binding ability and that bind
Finite element methods for incompressible flow problems
John, Volker
2016-01-01
This book explores finite element methods for incompressible flow problems: Stokes equations, stationary Navier-Stokes equations, and time-dependent Navier-Stokes equations. It focuses on numerical analysis, but also discusses the practical use of these methods and includes numerical illustrations. It also provides a comprehensive overview of analytical results for turbulence models. The proofs are presented step by step, allowing readers to more easily understand the analytical techniques.
Huebner, Claudia S.
2016-10-01
As a consequence of fluctuations in the index of refraction of the air, atmospheric turbulence causes scintillation, spatial and temporal blurring as well as global and local image motion creating geometric distortions. To mitigate these effects many different methods have been proposed. Global as well as local motion compensation in some form or other constitutes an integral part of many software-based approaches. For the estimation of motion vectors between consecutive frames simple methods like block matching are preferable to more complex algorithms like optical flow, at least when challenged with near real-time requirements. However, the processing power of commercially available computers continues to increase rapidly and the more powerful optical flow methods have the potential to outperform standard block matching methods. Therefore, in this paper three standard optical flow algorithms, namely Horn-Schunck (HS), Lucas-Kanade (LK) and Farnebäck (FB), are tested for their suitability to be employed for local motion compensation as part of a turbulence mitigation system. Their qualitative performance is evaluated and compared with that of three standard block matching methods, namely Exhaustive Search (ES), Adaptive Rood Pattern Search (ARPS) and Correlation based Search (CS).
Fajardo, Yamila; Ferrer, Laura; Gómez, Enrique; Garcias, Francesca; Casas, Monserrat; Cerdà, Víctor
2008-01-01
A new procedure for automatic separation and preconcentration of 241Am and 239+240Pu from interfering matrixes using transuranide (TRU)-resin is proposed. Combination of the multisyringe flow injection analysis and multipumping flow system techniques with the TRU-resin allows carrying out the sampling treatment and separation in a short time using large sample volumes. Americium is eluted from the column with 4 mol L(-1) hydrochloric acid, and then plutonium is separated via on-column Pu(IV) reduction to Pu(III) with titanium(III) chloride. The corresponding alpha activities are measured off-line, with a relative standard deviation of 3% and a lower limit of detection of 0.004 Bq mL(-1), by using a multiplanchet low-background proportional counter.
Maslen, S. H.
1974-01-01
A general method developed for the analysis of inviscid hypersonic shock layers is discussed for application to the case of the shuttle vehicle at high (65 deg) angle of attack. The associated extensive subsonic flow region caused convergence difficulties whose resolution is discussed. It is required that the solution be smoother than anticipated.
Rogers, David F.
1992-10-01
The major thrust of this book is to present a technique of analysis that aids the formulation, understanding, and solution of problems of viscous flow. The intent is to avoid providing a "canned" program to solve a problem, offering instead a way to recognize the underlying physical, mathematical, and modeling concepts inherent in the solutions. The reader must first choose a mathematical model and derive governing equations based on realistic assumptions, or become aware of the limitations and assumptions associated with existing models. An appropriate solution technique is then selected. The solution technique may be either analytical or numerical. Computer-aided analysis algorithms supplement the classical analyses. The book begins by deriving the Navier-Stokes equation for a viscous compressible variable property fluid. The second chapter considers exact solutions of the incompressible hydrodynamic boundary layer equations solved with and without mass transfer at the wall. Forced convection, free convection, and the compressible laminar boundary layer are discussed in the remaining chapters. The text unifies the various topics by tracing a logical progression from simple to complex governing differential equations and boundary conditions. Numerical, parametric, and directed analysis problems are included at the end of each chapter.
Orbak, Recep; Dayi, Ertunç
2003-02-01
The aim of this study was to determine whether there was any change in T-lymphocyte subsets in patients with periocoronitis after the application of different treatment methods. Twenty-six patients with acute pericoronitis were included in the study. In every phase of the treatment (pretreatment, postcurettage, and postextraction), the biopsy samples were taken from the gingival tissues at sites of pericoronitis. Then, CD4(+) and CD8(+) lymphocyte and CD4(+)/CD8(+) ratio values were determined using flow cytometry in the biopsy samples. At the same time, gingival index (Löe-Silness) and plaque index (Silness-Löe) scores were recorded to assess the periodontal status in patients. To determine the correlation between the clinical measurements and the laboratory results obtained before the treatment, after curettage, and after extraction, we conducted an analysis using a paired t-test. The normal values in peripheral blood of CD4(+) and CD8(+) lymphocytes are 25% to 29% and 19% to 48%, respectively. However, the CD4(+) and CD8(+) lymphocyte values in the patients with acute pericoronitis were found to be 22.12% +/- 6.15% and 7.69% +/- 4.12%, respectively. These values are lower than the normal values. The CD4(+) lymphocyte value increased to 31.06% +/- 7.09% postcurettage and to 32.24% +/- 3.11% postextraction. The CD8(+) lymphocyte value increased to 16.21% +/- 5.27% postcurettage and to 18.25% +/- 3.13% postextraction. The CD4/CD8 ratio increased postcurettage and postextraction. This increase was statistically significant (P pericoronitis pathobiology.
Institute of Scientific and Technical Information of China (English)
YU Zhigang; RAABE Thomas; HEMKEN Gitta; BROCKMANN Uwe
2004-01-01
Several methods for analysis of dissolved total phosphorus in seawater were reviewed. Discussions were focused on UV irradiation and persulphate oxidation methods which are the most popular dissolved organic phosphorus determination methods presently. The compounds used for the phosphorus recovery test were categorized into three groups according to their chemical structure. It was found that low power UV irradiation can decompose P-O-C or P-C bonds efficiently but may be inefficient for P-O-P bonds. Heating-bath in acid condition is useful for decomposing P-O-P bonds. Using the continuous flow analysis system (Auto-analyzer Ⅱ), UV digestion and heating-bath, series experiments were carried out based on the above analysis. Eleven model compounds were employed for the phosphorus recovery test and the factors influencing the decomposition efficiency of dissolved compounds containing phosphorus were clarified. Finally,the optimal design for determination of dissolved total phosphorus in seawater based on the routine continuous flow analysis system was presented. For the organic mono-phosphate, the recovery is more than 90% and a recovery of 33%～51% was obtained for inorganic or organic polyphosphates. Up to now, this is the highest decomposition efficiency for dissolved phosphorus based on the continuous flow analysis system.
Weatherill, W. H.; Sebastian, J. D.; Ehlers, F. E.
1977-01-01
A finite difference method for solving the unsteady flow about harmonically oscillating wings is investigated. The procedure is based on separating the velocity potential into steady and unsteady parts and linearing the resulting unsteady differential equation for small disturbances. Solutions are obtained using relaxation procedures. The means for improving the solution stability characteristics of the relaxation process are explored. A direct procedure is formulated which permits obtaining solutions for combinations of Mach number and reduced frequency for which the relaxation process has proved unstable. The pressure distribution for an aspect ratio 5 rectangular wing oscillating in pitch is presented.
Analysis and Improvement of Covert Flow Tree Method%隐蔽流树方法的分析与改进
Institute of Scientific and Technical Information of China (English)
王聪聪; 鞠时光; 宋香梅
2012-01-01
利用隐蔽流树方法搜索隐蔽通道时,获得的操作序列中只有极少部分真正构成隐蔽通道,增加了后续手工分析的工作量.为此,提出一种改进的隐蔽流树方法.根据信息流图进行建树,设计信息流规则,并给出隐蔽流树的自动分析算法.以一个文件系统为例进行分析,结果验证了改进方法的正确性.%When using Covert Flow Tree(CFT) method to search covert channel, only few operation sequences really constitute covert channel. It increases the subsequent manual analysis work. In order to solve this problem, this paper proposes an improved Covert Flow Tree(CFT) method. It uses the information flow graph to constitute trees, designs the statement information flow rule, and gives the tree traversal algorithm for automated analysis. It uses the pedagogical file system as analyzing example, and result shows the accuracy of the improved method.
Flow Injection Analysis in Industrial Biotechnology
DEFF Research Database (Denmark)
Hansen, Elo Harald; Miró, Manuel
2009-01-01
Flow injection analysis (FIA) is an analytical chemical continuous-flow (CF) method which in contrast to traditional CF-procedures does not rely on complete physical mixing (homogenisation) of the sample and the reagent(s) or on attaining chemical equilibria of the chemical reactions involved. Ex...
Directory of Open Access Journals (Sweden)
Zoran D Protić
2010-01-01
Full Text Available Geometry analysis of the axial fan impeller, experimentally obtained operating characteristics and experimental investigations of the turbulent swirl flow generated behind the impeller are presented in this paper. Formerly designed and manufactured, axial fan impeller blade geometry (originally designed by Prof. Dr-Ing. Z. Protić† has been digitized using a three-dimensional (3D scanner. In parallel, the same impeller has been modeled by beta version software for modeling axial turbomachines, based on modified classical calculation. These results were compared. Then, the axial fan operating characteristics were measured on the standardized test rig in the Laboratory for Hydraulic Machinery and Energy Systems, Faculty of Mechanical Engineering, University of Belgrade. Optimum blade impeller position was determined on the basis of these results. Afterwards, the impeller with optimum angle, without outlet vanes, was positioned in a circular pipe. Rotational speed has been varied in the range from 500 till 2500rpm. Reynolds numbers generated in this way, calculated for axial velocity component, were in the range from 0,8·105 till 6·105. LDA (Laser Doppler Anemometry measurements and stereo PIV (Particle Image Velocimetry measurements of the 3D velocity field in the swirl turbulent fluid flow behind the axial fan have been performed for each regime. Obtained results point out extraordinary complexity of the structure of generated 3D turbulent velocity fields.
Subcubic Control Flow Analysis Algorithms
DEFF Research Database (Denmark)
Midtgaard, Jan; Van Horn, David
We give the first direct subcubic algorithm for performing control flow analysis of higher-order functional programs. Despite the long held belief that inclusion-based flow analysis could not surpass the ``cubic bottleneck, '' we apply known set compression techniques to obtain an algorithm...... that runs in time O(n^3/log n) on a unit cost random-access memory model machine. Moreover, we refine the initial flow analysis into two more precise analyses incorporating notions of reachability. We give subcubic algorithms for these more precise analyses and relate them to an existing analysis from...
Directory of Open Access Journals (Sweden)
Liu Yang
2014-01-01
Full Text Available Locational marginal prices (LMPs are influenced by various factors in the electricity market; knowing the sensitivity information of LMPs is very important for both the purchase and the consumer. This paper presents a united method to compute the sensitivities of LMPs based on the optimal power flow (OPF. The Karush-Kuhn-Tucher (KKT system to solve LMPs can be transferred into an equation system by using an NCP function, and then by using the properties of the derivative of the semismooth NCP function, this paper provides a simultaneous obtention of the sensitivities of LMPs with respect to power demands, the cost of production, voltage boundary, and so forth. Numerical examples illustrate the concepts presented and the proposed methodology by a 6-bus electric energy system. Some relevant conclusions are drawn in the end.
Xu, Xiao-yan; Nie, Xiao-cui; Ma, Hai-ying; Song, Guo-qing; Zhang, Xiao-tong; Jin, Yu-nan; Yu, Yan-qiu
2015-04-01
Flow cytometry method (FCM) is a generally accepted tool to analyze apoptosis. Although apoptosis assay kit was applied by many companies, the manufacturers were not consistent with whether using Trypsin with EDTA to collect the adherent cells. In another words, the influence of EDTA on apoptotic ratio is not clear. In this work, we compared the proportion of apoptotic cells with EDTA or EDTA-free Trypsin treatment by FCM. We concluded that Trypsin with or without EDTA has little influence on the proportion of apoptotic cells. In addition, we found that the ratio of necrosis and apoptosis was different in cells collected by scraping. WAVE2 protein was analyzed as a typical example for movement related protein. WAVE2 expression is elevated in the EDTA Trypsin treated group, compared with EDTA-free Trypsin treatment and scrapping group.
Directory of Open Access Journals (Sweden)
Marković Jelena Đ.
2013-01-01
Full Text Available In order to obtain a better heat transfer, it is important to enhance fluid mixing in heat exchangers. Since there are negative effects when heat exchangers are operating in turbulent regime (like significant pressure drop, increased size of the pump it is necessary to apply the techniques which would provide better fluid mixing when heat exchangers are operating in laminar regime. Investigations have shown that use of sinusoidal instead of flat plates results in this effect. This study is a result of two dimensional simulation of fluid flow between two parallel sinusoidal plates. Simulation was done with the use of modified Openlb code, based on lattice Boltzmann method. Reynolds number was varied from 200 to 1000, and space between the plates was varied from 3cm to 5 cm. Results showed that sinusoidal plates enhance fluid mixing, especially with greater values of Re and smaller space between the plates, which is in agreement with previous investigations.
Beljadid, Abdelaziz; Mohammadian, Abdolmajid; Qiblawey, Hazim
2016-10-01
The discretization of the shallow water system on unstructured grids can lead to spurious modes which usually can affect accuracy and/or cause stability problems. This paper introduces a new approach for stability analysis of unstructured linear finite volume schemes for linear shallow water equations with the Coriolis Effect using spectra, pseudospectra, and singular value decomposition. The discrete operator of the scheme is the principal parameter used in the analysis. It is shown that unstructured grids have a large influence on operator normality. In some cases the eigenvectors of the operator can be far from orthogonal, which leads to amplification of solutions and/or stability problems. Large amplifications of the solution can be observed, even for discrete operators which respect the condition of asymptotic stability, and in some cases even for Lax-Richtmyer stable methods. The pseudospectra are shown to be efficient for the verification of stability of finite volume methods for linear shallow water equations. In some cases, the singular value decomposition is employed for further analysis in order to provide more information about the existence of unstable modes. The results of the analysis can be helpful in choosing the type of mesh, the appropriate placements of the variables of the system on the grid, and the suitable discretization method which is stable for a wide range of modes.
Information Flow Analysis for VHDL
DEFF Research Database (Denmark)
Tolstrup, Terkel Kristian; Nielson, Flemming; Nielson, Hanne Riis
2005-01-01
We describe a fragment of the hardware description language VHDL that is suitable for implementing the Advanced Encryption Standard algorithm. We then define an Information Flow analysis as required by the international standard Common Criteria. The goal of the analysis is to identify the entire...... information flow through the VHDL program. The result of the analysis is presented as a non-transitive directed graph that connects those nodes (representing either variables or signals) where an information flow might occur. We compare our approach to that of Kemmerer and conclude that our approach yields...
DEFF Research Database (Denmark)
Hansen, Elo Harald
1998-01-01
Learning objectives:* To provide an introduction to automated assays* To describe the basic principles of FIA * To demonstrate the capabilities of FIA in relation to batch assays and conventional continuous flow systems* To show that FIA allows one to augment existing analytical techniques* To sh...
Flow cytometric detection method for DNA samples
Energy Technology Data Exchange (ETDEWEB)
Nasarabadi,Shanavaz (Livermore, CA); Langlois, Richard G. (Livermore, CA); Venkateswaran, Kodumudi S. (Round Rock, TX)
2011-07-05
Disclosed herein are two methods for rapid multiplex analysis to determine the presence and identity of target DNA sequences within a DNA sample. Both methods use reporting DNA sequences, e.g., modified conventional Taqman.RTM. probes, to combine multiplex PCR amplification with microsphere-based hybridization using flow cytometry means of detection. Real-time PCR detection can also be incorporated. The first method uses a cyanine dye, such as, Cy3.TM., as the reporter linked to the 5' end of a reporting DNA sequence. The second method positions a reporter dye, e.g., FAM.TM. on the 3' end of the reporting DNA sequence and a quencher dye, e.g., TAMRA.TM., on the 5' end.
Analysis of hydrogeological flow responses in Olkiluoto
Energy Technology Data Exchange (ETDEWEB)
Ahokas, H.; Rouhiainen, P.; Komulainen, J.; Poellaenen, J. [Poeyry Finland Oy, Vantaa (Finland)
2014-04-15
As part of the programme for the final disposal of spent nuclear fuel, an analysis of the flow responses caused by ONKALO leakages or other activities on the site has been compiled. Leakages into ONKALO or other activities, such as pumping in connection with groundwater sampling, cause changes in flow conditions in adjacent drillholes. Flows in open drillholes have been measured with the PFL-tool (PFL-DIFF), several times in some holes, as part of Olkiluoto Monitoring Programme (OMO) or in conjunction of interference test campaigns carried out in Olkiluoto. The main objective of the study is to analyse differences detected between flow measurements without pumping. PFL-measurements were started in 1997 and all the holes have been measured. In total, measurements have been repeated in 32 holes, which enables a study of possible changes. The development of interpretation methods to detect and quantify flow changes was an important part of this work. The determination of the exact flow response is a challenging task. Changes are caused in flow also by seasonal effects, which complicate an unambiguous analysis of the observed parameters. Overlapping activities (sinks) behind flow changes make the analysis difficult. In addition, the role of other open holes close to the observation hole can be significant. They may cause flow responses, which would not have been detected without their existence. Nevertheless, unambiguous flow responses caused by the pumping of a drillhole or leaking tunnels have been detected in scales from ca. 10 m to over 1 km. (orig.)
Flow Analysis for the Falkner–Skan Wedge Flow
DEFF Research Database (Denmark)
Bararnia, H; Haghparast, N; Miansari, M
2012-01-01
the constant coefficients in the approximated solution. The effects of the polynomial terms of HAM are considered and the accuracy of the results is shown, which increases with the increasing polynomial terms of HAM. Analytical results for the dimensionless velocity and temperature profiles of the wedge flow......In this article an analytical technique, namely the homotopy analysis method (HAM), is applied to solve the momentum and energy equations in the case of a two-dimensional incompressible flow passing over a wedge. The trail and error method and Padé approximation strategies have been used to obtain...
Directory of Open Access Journals (Sweden)
Agus Seyawan
2016-11-01
Full Text Available The indication of an active geothermal system is shown by the presence of surface manifestations such as the hot spring in Kedungoleng, Paguyangan, Brebes, Central Java. The temperature of the largest hot spring reaches 74o C and there is an assumption that this is an outflow of Mount Slamet geothermal system. DC-resistivity, Spontaneous Potential (SP and Shallow Surface Temperature surveys were conducted to determine the subsurface structure as well as its correlation with the distribution of thermal fluid flow and shallow surface temperature. The subsurface resistivity has been investigated using 5 points of the Schlumberger configuration with 400 m separation for each point. For the fluid and temperature pattern, a measurement using 15 m interval in 3 lines of conducting fixed electrode configuration has been carried out, along with a 75 cm of depth of temperature measurement around the manifestation area. The thermal fluid is assumed by the low resistivity of 0.756 to 6.91Ωm and this indicates sandstone that has permeable characteristic. The fluid flows in two layers of Sandstone at more than 10 meter from surface of the first layer. Accordingly, the SP values have a range between -11- 11 mV and a depth interval of 13.42- 28.75 m and the distribution of temperature is between 24o-70oC at a tilting range of 46.06o-12.60o. Hence it can be inferred that the thermal fluid moves in the Northwest direction and is controlled by a fault structure stretching from Northwest to Southeast. Article History: Received Feb 3, 2016; Received in revised form July 11, 2016; Accepted August 13, 2016; Available online How to Cite This Article: Setyawan, A., Triahadini, A., Yuliananto, Y., Aribowo, Y., and Widiarso, D.A. (2016 Subsurface Structure and Fluid Flow Analyses Using Geophysical Methods in Geothermal Manifestation Area of Paguyangan, Brebes, Central Java. Int. Journal of Renewable Energy Development, 5(3, 171-177. http://dx.doi.org/10.14710/ijred.5.3.171-177
LFSTAT - Low-Flow Analysis in R
Koffler, Daniel; Laaha, Gregor
2013-04-01
The calculation of characteristic stream flow during dry conditions is a basic requirement for many problems in hydrology, ecohydrology and water resources management. As opposed to floods, a number of different indices are used to characterise low flows and streamflow droughts. Although these indices and methods of calculation have been well documented in the WMO Manual on Low-flow Estimation and Prediction [1], a comprehensive software was missing which enables a fast and standardized calculation of low flow statistics. We present the new software package lfstat to fill in this obvious gap. Our software package is based on the statistical open source software R, and expands it to analyse daily stream flow data records focusing on low-flows. As command-line based programs are not everyone's preference, we also offer a plug-in for the R-Commander, an easy to use graphical user interface (GUI) provided for R which is based on tcl/tk. The functionality of lfstat includes estimation methods for low-flow indices, extreme value statistics, deficit characteristics, and additional graphical methods to control the computation of complex indices and to illustrate the data. Beside the basic low flow indices, the baseflow index and recession constants can be computed. For extreme value statistics, state-of-the-art methods for L-moment based local and regional frequency analysis (RFA) are available. The tools for deficit characteristics include various pooling and threshold selection methods to support the calculation of drought duration and deficit indices. The most common graphics for low flow analysis are available, and the plots can be modified according to the user preferences. Graphics include hydrographs for different periods, flexible streamflow deficit plots, baseflow visualisation, recession diagnostic, flow duration curves as well as double mass curves, and many more. From a technical point of view, the package uses a S3-class called lfobj (low-flow objects). This
Li, Q.; Wu, D. J.
2013-09-01
The use of concrete bridges in urban rail transit systems has raised many concerns regarding low-frequency (20-200 Hz) structure-borne noise due to the vibration of bridges when subjected to moving trains. Understanding the mechanism that determines the dominant frequencies of bridge vibrations is essential for both vibration and noise reduction. This paper presents a general procedure based on the force method to obtain the power flows within a coupled vehicle-track-bridge system, the point mobility of the system and the dynamic interaction forces connecting various components. The general coupling system consists of multi-rigid-bodies for the vehicles, infinite Euler beams representing the rails, two-dimensional or three-dimensional elements of the concrete bridges, and spring-dashpot pairs to model the wheel-rail contacts, the vehicle suspensions, the rail pads and the bridge bearings. The dynamic interaction of the coupled system is solved in the frequency domain by assuming the combined wheel-rail roughness moves forward relative to the stationary vehicles. The proposed procedure is first applied to a rail on discrete supports and then to a real urban rail transit U-shaped concrete bridge. The computed results show that the wheel-rail contact forces, the power flows to the rail/bridge subsystem and the accelerations of the bridge are primarily dominated by the contents around the natural frequency of a single wheel adhered to the elastically supported rail. If the ath node of the mth spring-dashpot pair and the bth node of the nth spring-dashpot pair are connected to the same rigid body, then δmnab(ω) can be expressed as δmnab(ω)=-{(}/{Mlω}, where Ml is the mass of the lth rigid body. If the ath node of the mth spring-dashpot pair and the bth node of the nth spring-dashpot pair are connected to the same infinite rail, δmnab(ω) can be expressed as [8] δmnab(ω)=-j{((e-je)}/{4EIk}, where xm and xn are the x-coordinates of the mth and nth spring
Method based on network flow simulation for sneak circuit analysis%基于网络流仿真的潜通路分析方法
Institute of Scientific and Technical Information of China (English)
邹涛; 马齐爽
2012-01-01
针对线索表法在分析潜通路问题过程中约束条件过多的问题,在人工神经网络分析法的基础上应用网络流仿真进行潜通路分析.根据电路元件的电气特性以及人工神经网络的特点,建立了元件的定性仿真模型,确定电路网络的构成方式.通过网络流仿真模拟电流在电路系统中的扩散过程,预测电路中负载的响应.通过对比电路网络中负载的设计响应以及通过分析预测得到的负载响应,就可以判断出电路网络是否存在潜通路问题,并且找到发生潜通路问题的原因.该方法可以正确预测电路网络中的负载响应,克服了线索表法的缺陷,减少对分析已知条件的要求以及人为因素对分析结果的影响.%To solve the too many constraints problem in sneak circuit analysis of clue table method,network flow simulation was applied in sneak circuit analysis based on the research of artificial neural network（ANN） analysis method.Electrical elements＇ qualitative simulation models were established and circuit network＇s composition method was determined,based on electrical and ANN characteristics.The network flow simulation method simulated the current diffusion process and predicted the loads＇ responses in circuit network.The analysis results showed whether there was sneak circuit problem.Compared the loads＇ responses between the circuit network design and simulation analysis forecast,the difference was the sneak circuit problem.By using this method,the loads＇ responses in circuit network can be predicted correctly,the defects of the clue table method can be overcome,the analysis requirements of known conditions and the effects of human factors on the analytical results can be reduced.The sneak circuit problems in real circuit network can be solved effectively by this method.
Directory of Open Access Journals (Sweden)
Navid Freidoonimehr
2015-01-01
Full Text Available The main purpose of this study is to present dual solutions for the problem of magneto-hydrodynamic Jeffery–Hamel nano-fluid flow in non-parallel walls. To do so, we employ a new analytical technique, Predictor Homotopy Analysis Method (PHAM. This effective method is capable to calculate all branches of the multiple solutions simultaneously. Moreover, comparison of the PHAM results with numerical results obtained by the shooting method coupled with a Runge-Kutta integration method illustrates the high accuracy for this technique. For the current problem, it is found that the multiple (dual solutions exist for some values of governing parameters especially for the convergent channel cases (α = -1. The fluid in the non-parallel walls, divergent and convergent channels, is the drinking water containing different nanoparticles; Copper oxide (CuO, Copper (Cu and Silver (Ag. The effects of nanoparticle volume fraction parameter (φ, Reynolds number (Re, magnetic parameter (Mn, and angle of the channel (α as well as different types of nanoparticles on the flow characteristics are discussed.
The Direct Method of Cash Flows.
Bosserman, David C.; Fischer, Mary
2000-01-01
Explains to college/university business officers how to comply with Governmental Accounting Standards Board Statements Nos. 34, 35, and 9, which require the direct method of presenting cash flows from operating activities and reconciliation of operating cash flows to operating income by fiscal year 2001. Institutions are urged to begin immediately…
The Direct Method of Cash Flows.
Bosserman, David C.; Fischer, Mary
2000-01-01
Explains to college/university business officers how to comply with Governmental Accounting Standards Board Statements Nos. 34, 35, and 9, which require the direct method of presenting cash flows from operating activities and reconciliation of operating cash flows to operating income by fiscal year 2001. Institutions are urged to begin immediately…
Recent advances in flow injection analysis.
Trojanowicz, Marek; Kołacińska, Kamila
2016-04-07
A dynamic development of methodologies of analytical flow injection measurements during four decades since their invention has reinforced the solid position of flow analysis in the arsenal of techniques and instrumentation of contemporary chemical analysis. With the number of published scientific papers exceeding 20,000, and advanced instrumentation available for environmental, food, and pharmaceutical analysis, flow analysis is well established as an extremely vital field of modern flow chemistry, which is developed simultaneously with methods of chemical synthesis carried out under flow conditions. This review work is based on almost 300 original papers published mostly in the last decade, with special emphasis put on presenting novel achievements from the most recent 2-3 years in order to indicate current development trends of this methodology. Besides the evolution of the design of whole measuring systems, and including especially new applications of various detections methods, several aspects of implications of progress in nanotechnology, and miniaturization of measuring systems for application in different field of modern chemical analysis are also discussed.
Fluorescent multiplex cell flow systems and methods
Merzaban, Jasmeen
2017-06-01
Systems and methods are provided for simultaneously assaying cell adhesion or cell rolling for multiple cell specimens. One embodiment provides a system for assaying adhesion or cell rolling of multiple cell specimens that includes a confocal imaging system containing a parallel plate flow chamber, a pump in fluid communication with the parallel plate flow chamber via a flow chamber inlet line and a cell suspension in fluid communication with the parallel plate flow chamber via a flow chamber outlet line. The system also includes a laser scanning system in electronic communication with the confocal imaging system, and a computer in communication with the confocal imaging system and laser scanning system. In certain embodiments, the laser scanning system emits multiple electromagnetic wavelengths simultaneously it cause multiple fluorescent labels having different excitation wavelength maximums to fluoresce. The system can simultaneously capture real-time fluorescence images from at least seven cell specimens in the parallel plate flow chamber.
Energy Technology Data Exchange (ETDEWEB)
Wu, Horng-Wen; Gu, Hui-Wen [Department of System and Naval Mechatronic Engineering, National Cheng Kung University, 1 Ta-Hsueh Road, Tainan 701 (China)
2010-06-01
This study has applied the L{sub 18} 2 x 3{sup 7} orthogonal array of the Taguchi method to determine the optimal combination of six primary operating parameters (flow orientation, temperature of fuel cell, anode and cathode humidification temperatures, anode, and cathode stoichiometric flow ratios) of a PEM fuel cell. The optimal combination factor is co-flow, a cell temperature of 333 K, an anode humidification temperature of 353 K, a cathode humidification temperature of 333 K, a stoichiometric flow ratio for hydrogen of 2, and a stoichiometric flow ratio for oxygen of 3; and the amount of maximum power is 17.61 W. The results for the experiment indicate that flow orientation, temperature of fuel cell, and anode and cathode humidification temperatures are significant factors for affecting the performance. Furthermore, this study simulates the transport phenomenon and electrochemical reactions using a finite-element method at the optimal combination factor from the experimental results of Taguchi method. (author)
Directory of Open Access Journals (Sweden)
Mehmet KURBAN
2007-03-01
Full Text Available In this paper, the economic dispatch and optimal power flow (OPF methods for the purpose of supplying the load demand with minimum cost is used for 22-bus 380-kV power system in Turkey which consists of 8 thermal plants operated by EUAS (Electricity Generation Co. Inc.and the results found are analyzed comparatively. The results of analysis are given in tables and figures. The analysis made is implemented by the software using MATLAB®. Furthermore, the software can be used for different power systems by using the graphical user interface (GUI. All data used in this study is taken from TEIAS (Transmission System Operator of Turkey and EUAS.
Quantitative transverse flow assessment using OCT speckle decorrelation analysis
Liu, Xuan; Huang, Yong; Ramella-Roman, Jessica C.; Kang, Jin U.
2013-03-01
In this study, we demonstrate the use of inter-Ascan speckle decorrelation analysis of optical coherence tomography (OCT) to assess fluid flow. This method allows quantitative measurement of fluid flow in a plane normal to the scanning beam. To validate this method, OCT images were obtained from a micro fluid channel with bovine milk flowing at different speeds. We also imaged a blood vessel from in vivo animal models and performed speckle analysis to asses blood flow.
DEFF Research Database (Denmark)
Sandgaard, N C F; Andersen, J L; Holstein-Rathlou, N-H;
2002-01-01
We have measured total renal blood flow (TRBF) as the difference between signals from ultrasound flow probes implanted around the aorta above and below the renal arteries. The repeatability of the method was investigated by repeated, continuous infusions of angiotensin II and endothelin-1 seven...... arterial blood pressure by 49% and decreased TRBF by 12%, providing an increase in renal vascular resistance of 69%. Dynamic analysis showed autoregulation of renal blood flow in the frequency range ... of TRBF by aortic blood flow subtraction is a practical and reliable method that allows direct comparison of excretory function and renal blood flow from two kidneys. The method also allows direct comparison between TRBF and flow in the caudal aorta....
Boundary element method for internal axisymmetric flow
Directory of Open Access Journals (Sweden)
Gokhman Alexander
1999-01-01
Full Text Available We present an accurate fast method for the computation of potential internal axisymmetric flow based on the boundary element technique. We prove that the computed velocity field asymptotically satisfies reasonable boundary conditions at infinity for various types of inlet/exit. Computation of internal axisymmetric potential flow is an essential ingredient in the three-dimensional problem of computation of velocity fields in turbomachines. We include the results of a practical application of the method to the computation of flow in turbomachines of Kaplan and Francis types.
A review of the flow analysis methods of metabolic network%代谢网络流分析方法概述
Institute of Scientific and Technical Information of China (English)
庞建; 刘占英; 郝敏
2016-01-01
The microbial metabolic network is one of important fields of systems biology .The metabolic network flow analysis method has great significance in studying metabolic network properties .Metabolic network flow analysis method is a key to understand the rela-tionship between metabolic network structure and function , metabolic flow and gene expression .It has an important realistic signifi-cance in analyzing disease , identify target for drugs , pharmaceutical engineering and genetic modification .Several kinds of metabolic network flow analysis methods were reviewed in the paper in order to supply a reference for analyzing metabolic flux and thus guiding the experiments researches as well .They are flux balance analysis ( FBA) , minimization of metabolic adjustment ( MOMA) , regulatory on off minimization(ROOM), dynamic flux balance analysis with linear quadratic regulator (DFBA-LQR), the analysis of flow range (FVA), a bi-level programming framework for identifying gene knockout strategies (OptKnoock), up/down regulations of gene expres-sion(OptReg) and the framework for redesign of production systems (OptStrain).%生物体代谢网络模型是系统生物学的重要研究内容之一，代谢网络流分析方法在代谢网络分析中具有重要意义。了解代谢网络流量分析方法有助于理解代谢网络结构和功能的关系，代谢流量与基因表达的关系，在分析疾病，识别药物靶标，制药工程和基因改造方面具有重要现实意义。综述了几种常用代谢网络流分析方法：流平衡分析（ FBA）、代谢调节最小化分析（ MOMA）、调节开关最小化分析（ ROOM）、含有二次线性规划的动态流平衡分析方法（DFBA－LQR）、流量范围分析（FVA）、双层规划策略识别基因敲除（OptKnock）、基因表达上调下调（OptReg）和重新设计生产系统的计算框架（ OptStrain）等，以期为代谢网络流分析提供参考，并进一步为实验研究提供指导。
Effects of momentum conservation on the analysis of anisotropic flow
Energy Technology Data Exchange (ETDEWEB)
Borghini, N.; Dinh, P.M.; Ollitrault, J.-Y.; Poskanzer, A.M.; Voloshin, S.A.
2002-02-05
We present a general method for taking into account correlations due to momentum conservation in the analysis of anisotropic flow. Momentum conservation mostly affects the first harmonic in azimuthal distributions, i.e., directed flow. It also modifies higher harmonics, for instance elliptic flow, when they are measured with respect to a first harmonic event plane such as one determined with the standard transverse momentum method. Our method is illustrated by application to NA49 data on pion directed flow.
Institute of Scientific and Technical Information of China (English)
LEI Wen-jie
2008-01-01
The coal-gas existing condition was ameliorated in the coal seams prone to coal-gas outburst adopting the mining method of protective strata. The gas volume and the gas pressure were reduced synchronously in the protected coal seam, and the coal seam of high permeability prone to the coal-gas outburst was changed into that of low perme-ability with no proneness to the coal-gas outburst. The D15 coal seam was treated as the protective strata, and the D16-17 coal seam was treated as the protected strata in the Fifth coal mine in the Pingdingshan Coal Mining Group. The distance between the two coal seams was 5 m averagely, clarified into the extreme short-range protective strata. The numerical analysis was based on the theory of the porous media flow with the finite ele-ment method. The gas flow process and the change mechanism of the coal-gas pressure were analyzed in the process of mining the protective strata.
Wangfuengkanagul, N; Siangproh, W; Chailapakul, O
2004-12-15
A method using flow injection (FI) with amperometric detection at anodized boron-doped diamond (BDD) thin films has been developed and applied for the determination of tetracycline antibiotics (tetracycline, chlortetracycline, oxytetracycline and doxycycline). The electrochemical oxidation of the tetracycline antibiotics was studied at various carbon electrodes including glassy carbon (GC), as-deposited BDD and anodized BDD electrodes using cyclic voltammetry. The anodized BDD electrode exhibited well-defined irreversible cyclic voltammograms for the oxidation of tetracycline antibiotics with the highest current signals compared to the as-deposited BDD and glassy carbon electrodes. Low detection limit of 10nM (signal-to-noise ratio = 3) was achieved for each drug when using flow injection analysis with amperometric detection at anodized BDD electrodes. Linear calibrations were obtained from 0.1 to 50mM for tetracycline and 0.5-50mM for chlortetracycline, oxytetracycline and doxycycline. The proposed method has been successfully applied to determine the tetracycline antibiotics in some drug formulations. The results obtained in percent found (99.50-103.01%) were comparable to dose labeled.
PCCF flow analysis -- DR Reactor
Energy Technology Data Exchange (ETDEWEB)
Calkin, J.F.
1961-04-26
This report contains an analysis of PCCF tube flow and Panellit pressure relations at DR reactor. Supply curves are presented at front header pressures from 480 to 600 psig using cold water and the standard 0.236 inch orifice with taper down stream and the pigtail valve (plug or ball) open. Demand curves are presented for slug column lengths of 200 inches to 400 inches using 1.44 inch O.D. solid poison pieces (either Al or Pb-Cd) and cold water with a rear header pressure of 50 psig. Figure 1 is a graph of Panellit pressure vs. flow with the above supply and demand curves and clearly shows the effect of front header pressure and charge length on flow.
Fourier time spectral method for subsonic and transonic flows
Institute of Scientific and Technical Information of China (English)
Lei Zhan; Feng Liu; Dimitri Papamoschou
2016-01-01
The time accuracy of the exponentially accu-rate Fourier time spectral method (TSM) is examined and compared with a conventional 2nd-order backward differ-ence formula (BDF) method for periodic unsteady flows. In particular, detailed error analysis based on numerical com-putations is performed on the accuracy of resolving the local pressure coefficient and global integrated force coefficients for smooth subsonic and non-smooth transonic flows with moving shock waves on a pitching airfoil. For smooth sub-sonic flows, the Fourier TSM method offers a significant accuracy advantage over the BDF method for the predic-tion of both the local pressure coefficient and integrated force coefficients. For transonic flows where the motion of the discontinuous shock wave contributes significant higher-order harmonic contents to the local pressure fluctuations, a sufficient number of modes must be included before the Fourier TSM provides an advantage over the BDF method. The Fourier TSM, however, still offers better accuracy than the BDF method for integrated force coefficients even for transonic flows. A problem of non-symmetric solutions for symmetric periodic flows due to the use of odd numbers of intervals is uncovered and analyzed. A frequency-searching method is proposed for problems where the frequency is not known a priori. The method is tested on the vortex shedding problem of the flow over a circular cylinder.
Abnormal traffic flow data detection based on wavelet analysis
Directory of Open Access Journals (Sweden)
Xiao Qian
2016-01-01
Full Text Available In view of the traffic flow data of non-stationary, the abnormal data detection is difficult.proposed basing on the wavelet analysis and least squares method of abnormal traffic flow data detection in this paper.First using wavelet analysis to make the traffic flow data of high frequency and low frequency component and separation, and then, combined with least square method to find abnormal points in the reconstructed signal data.Wavelet analysis and least square method, the simulation results show that using wavelet analysis of abnormal traffic flow data detection, effectively reduce the detection results of misjudgment rate and false negative rate.
Meel-van den Abeelen, Aisha S S; Simpson, David M; Wang, Lotte J Y; Slump, Cornelis H; Zhang, Rong; Tarumi, Takashi; Rickards, Caroline A; Payne, Stephen; Mitsis, Georgios D; Kostoglou, Kyriaki; Marmarelis, Vasilis; Shin, Dae; Tzeng, Yu-Chieh; Ainslie, Philip N; Gommer, Erik; Müller, Martin; Dorado, Alexander C; Smielewski, Peter; Yelicich, Bernardo; Puppo, Corina; Liu, Xiuyun; Czosnyka, Marek; Wang, Cheng-Yen; Novak, Vera; Panerai, Ronney B; Claassen, Jurgen A H R
2014-05-01
Transfer function analysis (TFA) is a frequently used method to assess dynamic cerebral autoregulation (CA) using spontaneous oscillations in blood pressure (BP) and cerebral blood flow velocity (CBFV). However, controversies and variations exist in how research groups utilise TFA, causing high variability in interpretation. The objective of this study was to evaluate between-centre variability in TFA outcome metrics. 15 centres analysed the same 70 BP and CBFV datasets from healthy subjects (n=50 rest; n=20 during hypercapnia); 10 additional datasets were computer-generated. Each centre used their in-house TFA methods; however, certain parameters were specified to reduce a priori between-centre variability. Hypercapnia was used to assess discriminatory performance and synthetic data to evaluate effects of parameter settings. Results were analysed using the Mann-Whitney test and logistic regression. A large non-homogeneous variation was found in TFA outcome metrics between the centres. Logistic regression demonstrated that 11 centres were able to distinguish between normal and impaired CA with an AUC>0.85. Further analysis identified TFA settings that are associated with large variation in outcome measures. These results indicate the need for standardisation of TFA settings in order to reduce between-centre variability and to allow accurate comparison between studies. Suggestions on optimal signal processing methods are proposed.
Directory of Open Access Journals (Sweden)
M. M. Rashidi
2012-01-01
Full Text Available In this study, a steady, incompressible, and laminar-free convective flow of a two-dimensional electrically conducting viscoelastic fluid over a moving stretching surface through a porous medium is considered. The boundary-layer equations are derived by considering Boussinesq and boundary-layer approximations. The nonlinear ordinary differential equations for the momentum and energy equations are obtained and solved analytically by using homotopy analysis method (HAM with two auxiliary parameters for two classes of visco-elastic fluid (Walters’ liquid B and second-grade fluid. It is clear that by the use of second auxiliary parameter, the straight line region in ℏ-curve increases and the convergence accelerates. This research is performed by considering two different boundary conditions: (a prescribed surface temperature (PST and (b prescribed heat flux (PHF. The effect of involved parameters on velocity and temperature is investigated.
This method provides a procedure for the determination of dissolved silicate concentration in estuarine and coastal waters. The dissolved silicate is mainly in the form of silicic acid, H SiO , in estuarine and 4 4 coastal waters. All soluble silicate, including colloidal silici...
Numerical Analysis for the Air Flow of Cross Flow Fan
Sakai, Hirokazu; Tokushge, Satoshi; Ishikawa, Masatoshi; Ishihara, Takuya
There are many factors for designing the cross flow fan. Therefore, the performance of cross flow fan is not clear yet. We can analyze the transient flow of a cross flow fan using sliding mesh approach. One of the tasks using Computational Fluid Dynamics (CFD) is a way of modeling for analysis heat exchangers with cross flow fan. These tasks are very important for design. The paper has a modeling of heat exchangers and meshing the fan blades. The next tasks, we focus the ability of cross flow fan when we change the geometry of fan blades.
Analysis of Secondary Flows in Centrifugal Impellers
Directory of Open Access Journals (Sweden)
Brun Klaus
2005-01-01
Full Text Available Secondary flows are undesirable in centrifugal compressors as they are a direct cause for flow (head losses, create nonuniform meridional flow profiles, potentially induce flow separation/stall, and contribute to impeller flow slip; that is, secondary flows negatively affect the compressor performance. A model based on the vorticity equation for a rotating system was developed to determine the streamwise vorticity from the normal and binormal vorticity components (which are known from the meridional flow profile. Using the streamwise vorticity results and the small shear-large disturbance flow method, the onset, direction, and magnitude of circulatory secondary flows in a shrouded centrifugal impeller can be predicted. This model is also used to estimate head losses due to secondary flows in a centrifugal flow impeller. The described method can be employed early in the design process to develop impeller flow shapes that intrinsically reduce secondary flows rather than using disruptive elements such as splitter vanes to accomplish this task.
Stereo Scene Flow for 3D Motion Analysis
Wedel, Andreas
2011-01-01
This book presents methods for estimating optical flow and scene flow motion with high accuracy, focusing on the practical application of these methods in camera-based driver assistance systems. Clearly and logically structured, the book builds from basic themes to more advanced concepts, culminating in the development of a novel, accurate and robust optic flow method. Features: reviews the major advances in motion estimation and motion analysis, and the latest progress of dense optical flow algorithms; investigates the use of residual images for optical flow; examines methods for deriving mot
Numerical flow analysis of hydro power stations
Ostermann, Lars; Seidel, Christian
2017-07-01
For the hydraulic engineering and design of hydro power stations and their hydraulic optimisation, mainly experimental studies of the physical submodel or of the full model at the hydraulics laboratory are carried out. Partially, the flow analysis is done by means of computational fluid dynamics based on 2D and 3D methods and is a useful supplement to experimental studies. For the optimisation of hydro power stations, fast numerical methods would be appropriate to study the influence of a wide field of optimisation parameters and flow states. Among the 2D methods, especially the methods based on the shallow water equations are suitable for this field of application, since a lot of experience verified by in-situ measurements exists because of the widely used application of this method for the problems in hydraulic engineering. As necessary, a 3D model may supplement subsequently the optimisation of the hydro power station. The quality of the results of the 2D method for the optimisation of hydro power plants is investigated by means of the results of the optimisation of the hydraulic dividing pier compared to the results of the 3D flow analysis.
Werner, Kristin; Kälble, Solveig; Wolter, Sabine; Schneider, Erich H; Buschauer, Armin; Neumann, Detlef; Seifert, Roland
2015-10-01
The histamine H2 receptor (H2R) is a Gs protein-coupled receptor. Its activation leads to increases in the second messenger adenosine-3',5'-cyclic monophosphate (cAMP). Presently, several systems are established to characterize the pharmacological profile of the H2R, mostly requiring radioactive material, animal models, or human blood cells. This prompted us to establish a flow cytometric analysis with a fluorescently labeled formyl peptide receptor (FPR) ligand in order to investigate the H2R functionally and pharmacologically. First, we stimulated U937 promonocytes, which mature in a cAMP-dependent fashion upon H2R activation, with histamine (HA) or selective H2R agonists and measured increases in cAMP concentrations by mass spectrometry. Next, indicative for the maturation of U937 promonocytes, we assessed the FPR expression upon incubation with HA or H2R agonists. FPR expression was measured either indirectly by formyl peptide-induced changes in intracellular calcium concentrations ([Ca(2+)]i) or directly with the fluorescein-labeled FPR ligand fNleLFNleYK-Fl. HA and H2R agonists concentration-dependently induced FPR expression, and potencies and efficacies of fMLP-induced increases in [Ca(2+)]i and FPR density correlated linearly. Accordingly, flow cytometric analysis of FPR expression constitutes a simple, inexpensive, sensitive, and reliable method to characterize the H2R pharmacologically. Furthermore, we evaluated FPR expression at the mRNA level. Generally, quantitative real-time polymerase chain reaction confirmed functional data. Additionally, our study supports the concept of functional selectivity of the H2R, since we observed dissociations in the efficacies of HA and H2R agonists in cAMP accumulation and FPR expression.
Advanced overset methods for vortex dominated flows
Foster, Norman F.
A newly implemented computational method of high-order accuracy is presented for the accurate calculation of unsteady vortical structures that may produce aeroacoustic sources, or affect downstream structural responses. The method involves prediction of the mean flow field by solving the Navier-Stokes equations (NSE) using a computational fluid dynamics (CFD) solver that employs high-order discretization on overlapping (overset) grid systems. The method dramatically reduces the artificial dissipation and dispersion of vortical flow features that would ordinarily be lost or degraded with the use of current methods. Complex domains are discretized using an overset grid strategy that allows for the use of multiple high quality structured meshes. The high-order method is developed and incorporated into a generalized overset grid assembly scheme, which allows high-order spatial accuracy of the NSE solutions to be maintained across overset grid boundaries. Comparisons are made to calculations that do not preserve high-order accuracy at overset boundaries, and insight is obtained into the effects and sensitivities of different treatments of overlapping boundaries. A nested block adaptive mesh refinement (AMR) method has also been developed, within the context of the overset paradigm. The method is shown to significantly improve accuracy for a given computational cell count by tracking dynamic vortical features using appropriate dynamic refinement and coarsening, and its implementation in the context of the high-order overset method is presented. The computational procedures presented herein are tested against analytic and canonical cases (slightly compressible, M ≤ 0.5, and incompressible mean flows) in order to characterize the accuracy of flow field calculations using high-order discretization and overset schemes across overlapping grid boundaries. The methods are also extended to far more complex systems including the transport of rotorcraft hub vorticity to
Boundary integral methods for unsaturated flow
Energy Technology Data Exchange (ETDEWEB)
Martinez, M.J.; McTigue, D.F.
1990-12-31
Many large simulations may be required to assess the performance of Yucca Mountain as a possible site for the nations first high level nuclear waste repository. A boundary integral equation method (BIEM) is described for numerical analysis of quasilinear steady unsaturated flow in homogeneous material. The applicability of the exponential model for the dependence of hydraulic conductivity on pressure head is discussed briefly. This constitutive assumption is at the heart of the quasilinear transformation. Materials which display a wide distribution in pore-size are described reasonably well by the exponential. For materials with a narrow range in pore-size, the exponential is suitable over more limited ranges in pressure head. The numerical implementation of the BIEM is used to investigate the infiltration from a strip source to a water table. The net infiltration of moisture into a finite-depth layer is well-described by results for a semi-infinite layer if {alpha}D > 4, where {alpha} is the sorptive number and D is the depth to the water table. the distribution of moisture exhibits a similar dependence on {alpha}D. 11 refs., 4 figs.,
Transformation of Commercial Flows into Physical Flows of Electricity – Flow Based Method
Directory of Open Access Journals (Sweden)
M. Adamec
2009-01-01
Full Text Available We are witnesses of large – scale electricity transport between European countries under the umbrella of the UCTE organization. This is due to the inabilyof generators to satisfy the growing consumption in some regions. In this content, we distinguish between two types of flow. The first type is physical flow, which causes costs in the transmission grid, whilst the second type is commercial flow, which provides revenues for the market participants. The old methods for allocating transfer capacity fail to take this duality into account. The old methods that allocate transmission border capacity to “virtual” commercial flows which, in fact, will not flow over this border, do not lead to optimal allocation. Some flows are uselessly rejected and conversely, some accepted flows can cause congestion on another border. The Flow Based Allocation method (FBA is a method which aims to solve this problem.Another goal of FBA is to ensure sustainable development of expansion of transmission capacity. Transmission capacity is important, because it represents a way to establish better transmission system stability, and it provides a distribution channel for electricity to customers abroad. For optimal development, it is necessary to ensure the right division of revenue allocation among the market participants.This paper contains a brief description of the FBA method. Problems of revenue maximization and optimal revenue distribution are mentioned.
Power flow analysis for DC voltage droop controlled DC microgrids
DEFF Research Database (Denmark)
Li, Chendan; Chaudhary, Sanjay; Dragicevic, Tomislav
2014-01-01
This paper proposes a new algorithm for power flow analysis in droop controlled DC microgrids. By considering the droop control in the power flow analysis for the DC microgrid, when compared with traditional methods, more accurate analysis results can be obtained. The algorithm verification...... is carried out by comparing the calculation results with detailed time domain simulation results. With the droop parameters as variables in the power flow analysis, their effects on power sharing and secondary voltage regulation can now be analytically studied, and specialized optimization in the upper level...... control can also be made accordingly. Case studies on power sharing and secondary voltage regulation are carried out using proposed power flow analysis....
Information flow analysis of interactome networks.
Directory of Open Access Journals (Sweden)
Patrycja Vasilyev Missiuro
2009-04-01
Full Text Available Recent studies of cellular networks have revealed modular organizations of genes and proteins. For example, in interactome networks, a module refers to a group of interacting proteins that form molecular complexes and/or biochemical pathways and together mediate a biological process. However, it is still poorly understood how biological information is transmitted between different modules. We have developed information flow analysis, a new computational approach that identifies proteins central to the transmission of biological information throughout the network. In the information flow analysis, we represent an interactome network as an electrical circuit, where interactions are modeled as resistors and proteins as interconnecting junctions. Construing the propagation of biological signals as flow of electrical current, our method calculates an information flow score for every protein. Unlike previous metrics of network centrality such as degree or betweenness that only consider topological features, our approach incorporates confidence scores of protein-protein interactions and automatically considers all possible paths in a network when evaluating the importance of each protein. We apply our method to the interactome networks of Saccharomyces cerevisiae and Caenorhabditis elegans. We find that the likelihood of observing lethality and pleiotropy when a protein is eliminated is positively correlated with the protein's information flow score. Even among proteins of low degree or low betweenness, high information scores serve as a strong predictor of loss-of-function lethality or pleiotropy. The correlation between information flow scores and phenotypes supports our hypothesis that the proteins of high information flow reside in central positions in interactome networks. We also show that the ranks of information flow scores are more consistent than that of betweenness when a large amount of noisy data is added to an interactome. Finally, we
Analysis of Interregional Commodity Flows
Directory of Open Access Journals (Sweden)
Wirach Hirun
2010-01-01
Full Text Available Problem statement: Commodity Flow Survey (CFS was launched to collect comprehensive freight flow data throughout the kingdom of Thailand. The surveys database is the most complete collection of commodity flow data in Thailand. The need to reveal interregional freight characteristics using available data from the CFS led to the objectives of this research. Approach: An origin destination matrix based on province was calibrated using a flexible Box-Cox function form. It used maximum likelihood and the backward method for calibration and Root Mean Square Error (RMSE and Mean Relative Error (MRE to verify the models performance. Independent variables were classified into three groups: origin variable, destination variable and geographic variable. The origin variable represented the behavior of the trip as generated at the place of origin. Some consumption occurred at the origin. The employment and the average plant size variables were selected for potential productivity while personal income per capita and total populations were included to explain consumption behavior at the origin. Personal income per capita and total populations were selected for destination variables which act as proxy for final demand at the destination. The third category, distance, was the most conventional friction variable for geographical variables. Results: The calibrated model revealed that origin income, origin average plant size and origin population performed poorly. Therefore these variables were eliminated. The best developed model included four strongly significant variables at a 5% level: origin employment, destination population, destination income per capita and distance. Conclusion: The results showed that the selected variables and the Box-Cox functional form were successful in explaining behavior of interregional freight transportation in Thailand. The developed model was the first interregional freight transportation model to be
Morganti, Andrea; Becagli, Silvia; Castellano, Emiliano; Severi, Mirko; Traversi, Rita; Udisti, Roberto
2007-11-12
A method was developed for the quantitative determination of cations and anions in Antarctic ice cores at microgL(-1) and sub-microgL(-1) levels by ion chromatography (IC), after ultra-clean decontamination procedures. Strict manipulation and decontamination procedures were used in sub-sampling, in order to minimise sample contamination. Na+, NH4+, K+, Mg2+ and Ca2+ were determined by 12-min isocratic elution (H2SO4 eluent). Contemporaneously, in a parallel device, F-, MSA (methanesulfonic acid), Cl-, NO3- and SO4(2-) were analysed in a single 12-min run with multiple-step elution using Na2CO3/NaHCO3 as eluent. Melted ice samples were pumped from their still-closed containers (polystyrene accuvettes with polyethylene caps), shared between the two ion chromatographic systems, online filtered (0.45 microm Teflon membrane) and pre-concentrated (anions and cations pre-concentration columns) using a flow analysis system, thus avoiding uptake of contaminants from the laboratory atmosphere. Sensitivity, linear range, reproducibility and detection limit were evaluated for each chemical species. Anion or cation detection limits ranged from 0.01 to 0.15 microgL(-1) by using a relatively small sample volume (1.5 mL). Such values are significantly lower than those reported in literature for almost all the components. These methods were successfully applied to the analysis of cations and anions at trace levels in the Dome C ice core. The composition of the atmospheric aerosol for the last 850 kyr was reconstructed by high-resolution continuous chemical stratigraphies. Concentration trends in the last nine glacial-interglacial climatic cycles were shown and briefly discussed.
ANALYSIS OF MULTISCALE METHODS
Institute of Scientific and Technical Information of China (English)
Wei-nan E; Ping-bing Ming
2004-01-01
The heterogeneous multiscale method gives a general framework for the analysis of multiscale methods. In this paper, we demonstrate this by applying this framework to two canonical problems: The elliptic problem with multiscale coefficients and the quasicontinuum method.
Numerical Methods For Chemically Reacting Flows
Leveque, R. J.; Yee, H. C.
1990-01-01
Issues related to numerical stability, accuracy, and resolution discussed. Technical memorandum presents issues in numerical solution of hyperbolic conservation laws containing "stiff" (relatively large and rapidly changing) source terms. Such equations often used to represent chemically reacting flows. Usually solved by finite-difference numerical methods. Source terms generally necessitate use of small time and/or space steps to obtain sufficient resolution, especially at discontinuities, where incorrect mathematical modeling results in unphysical solutions.
Buoy Relay Method for Instantaneous Fluid Flow with Free Surface
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Several methods have been used to approximate free surface boundaries in finite-difference numerical simulations. Each of these methods has its advantages and disadvantages. This paper presents a new technique for the numerical solution of transient incompressible free surface fluid flows. This powerful method, which is based on the concepts of "Buoy positioning" and "Buoy relaying", successfully represents the free surface using a Lagrangian method on a Eulerian grid by directly solving the free surface evolution equation. The Eulerian finite-difference forms of the full Navier-Stokes equations are solved by the Successive over Relaxation (SOR) method with a set of buoys to keep track of the free surface. The capabilities of the analysis procedure are demonstrated through viscous free surface fluid flow examples. The method is simpler and more efficient than other methods especially in treating complicated free boundary configurations.
PIE Nacelle Flow Analysis and TCA Inlet Flow Quality Assessment
Shieh, C. F.; Arslan, Alan; Sundaran, P.; Kim, Suk; Won, Mark J.
1999-01-01
This presentation includes three topics: (1) Analysis of isolated boattail drag; (2) Computation of Technology Concept Airplane (TCA)-installed nacelle effects on aerodynamic performance; and (3) Assessment of TCA inlet flow quality.
Parametric and experimental analysis using a power flow approach
Cuschieri, J. M.
1990-01-01
A structural power flow approach for the analysis of structure-borne transmission of vibrations is used to analyze the influence of structural parameters on transmitted power. The parametric analysis is also performed using the Statistical Energy Analysis approach and the results are compared with those obtained using the power flow approach. The advantages of structural power flow analysis are demonstrated by comparing the type of results that are obtained by the two analytical methods. Also, to demonstrate that the power flow results represent a direct physical parameter that can be measured on a typical structure, an experimental study of structural power flow is presented. This experimental study presents results for an L shaped beam for which an available solution was already obtained. Various methods to measure vibrational power flow are compared to study their advantages and disadvantages.
Yin, Guanyi; Liu, Liming; Yuan, Chengcheng
2015-07-01
This study primarily examined the assessment of environmental risk in high intensity agricultural areas. Dongting Lake basin was taken as a case study, which is one of the major grain producing areas in China. Using data obtained from 1989 to 2012, we applied Material Flow Analysis (MFA) to show the material consumption, pollutant output and production storage in the agricultural-environmental system and assessed the environmental risk index on the basis of the MFA results. The results predicted that the status of the environmental quality of the Dongting Lake area is unsatisfactory for the foreseeable future. The direct material input (DMI) declined by 13.9%, the domestic processed output (DPO) increased by 28.21%, the intensity of material consumption (IMC) decreased by 36.7%, the intensity of material discharge (IMD) increased by 10%, the material productivity (MP) increased by 27 times, the environmental efficiency (EE) increased by 15.31 times, and the material storage (PAS) increased by 0.23%. The DMI and DPO was higher at rural places on the edge of cities, whereas the risk of urban agriculture has arisen due to the higher increasing rate of DMI and DPO in cities compared with the counties. The composite environmental risk index increased from 0.33 to 0.96, indicating that the total environmental risk changed gradually but seriously during the 24 years assessed. The driving factors that affect environmental risk in high intensity agriculture can be divided into five classes: social, economic, human, natural and disruptive incidents. This study discussed a number of effective measures for protecting the environment while ensuring food production yields. Additional research in other areas and certain improvements of this method in future studies may be necessary to develop a more effective method of managing and controlling agricultural-environmental interactions.
A new CFD modeling method for flow blockage accident investigations
Energy Technology Data Exchange (ETDEWEB)
Fan, Wenyuan, E-mail: fanwy@mail.ustc.edu.cn; Peng, Changhong, E-mail: pengch@ustc.edu.cn; Chen, Yangli, E-mail: chenyl@mail.ustc.edu.cn; Guo, Yun, E-mail: guoyun79@ustc.edu.cn
2016-07-15
Highlights: • Porous-jump treatment is applied to CFD simulation on flow blockages. • Porous-jump treatment predicts consistent results with direct CFD treatment. • Relap5 predicts abnormal flow rate profiles in MTR SFA blockage scenario. • Relap5 fails to simulate annular heat flux in blockage case of annular assembly. • Porous-jump treatment provides reasonable and generalized CFD results. - Abstract: Inlet flow blockages in both flat and annular plate-type fuel assemblies are simulated by (Computational Fluid Dynamics) CFD and system analysis methods, with blockage ratio ranging from 60 to 90%. For all the blockage scenarios, mass flow rate of the blocked channel drops dramatically as blockage ratio increases, while mass flow rates of non-blocked channels are almost steady. As a result of over-simplifications, the system code fails to capture details of mass flow rate profiles of non-blocked channels and power redistribution of fuel plates. In order to acquire generalized CFD results, a new blockage modeling method is developed by using the porous-jump condition. For comparisons, direct CFD simulations are conducted toward postulated blockages. For the porous-jump treatment, conservative flow and heat transfer conditions are predicted for the blocked channel, while consistent predictions are obtained for non-blocked channels. Besides, flow fields in the blocked channel, asymmetric power redistributions of fuel plates, and complex heat transfer phenomena in annular fuel assembly are obtained and discussed. The present study indicates that the porous-jump condition is a reasonable blockage modeling method, which predicts generalized CFD results for flow blockages.
Progress toward the analysis of complex propulsion installation flow phenomenon
Kern, P. R. A.; Hopcroft, R. G.
1983-01-01
A trend toward replacement of parametric model testing with parametric analysis for the design of aircraft is driven by the rapidly escalating cost of wind tunnel testing, the increasing availability of large fast computers, and powerful numerical flow algorithms. In connection with the complex flow phenomena characteristic of propulsion installations, it is now necessary to employ both parametric analysis and testing for design procedures. Powerful flow analysis techniques are available to predict local flow phenomena. However, the employment of these techniques is very expensive. It is, therefore, necessary to link these analyses with less powerful and less expensive procedures for an accurate analysis of propulsion installation flowfields. However, the interfacing and coupling processes needed are not available. The present investigation is concerned with progress made regarding the development of suitable linking methods. Attention is given to methods of analysis for predicting the flow around a nacelle coupled to a highly swept wing.
Numerical analysis of cavitation within slanted axial-flow pump
Institute of Scientific and Technical Information of China (English)
张睿; 陈红勋
2013-01-01
In this paper, the cavitating flow within a slanted axial-flow pump is numerically researched. The hydraulic and cavitation performance of the slanted axial-flow pump under different operation conditions are estimated. Compared with the experimental hydraulic performance curves, the numerical results show that the filter-based model is better than the standard k-e model to predict the parameters of hydraulic performance. In cavitation simulation, compared with the experimental results, the proposed numerical method has good predicting ability. Under different cavitation conditions, the internal cavitating flow fields within slanted axial-flow pump are investigated. Compared with flow visualization results, the major internal flow features can be effectively grasped. In order to explore the origin of the cavitation performance breakdown, the Boundary Vorticity Flux (BVF) is introduced to diagnose the cavitating flow fields. The analysis results indicate that the cavitation performance drop is relevant to the instability of cavitating flow on the blade suction surface.
Viscous incompressible flow simulation using penalty finite element method
Directory of Open Access Journals (Sweden)
Sharma R.L.
2012-04-01
Full Text Available Numerical analysis of Navier–Stokes equations in velocity– pressure variables with traction boundary conditions for isothermal incompressible flow is presented. Specific to this study is formulation of boundary conditions on synthetic boundary characterized by traction due to friction and surface tension. The traction and open boundary conditions have been investigated in detail. Navier-Stokes equations are discretized in time using Crank-Nicolson scheme and in space using Galerkin finite element method. Pressure being unknown and is decoupled from the computations. It is determined as post processing of the velocity field. The justification to simulate this class of flow problems is presented through benchmark tests - classical lid-driven cavity flowwidely used by numerous authors due to its simple geometry and complicated flow behavior and squeezed flow between two parallel plates amenable to analytical solution. Results are presented for very low to high Reynolds numbers and compared with the benchmark results.
New nodal methods for fluid flow equations
Michael, Edward-Pierre Edward
Several new highly accurate and highly efficient computational methods, called nodal integral methods (NIMs), for solving steady-state and time-dependent fluid flow equations have been developed. First, a new third order nodal integral method for solving the linear, two-dimensional, steady-state, convection-diffusion equation was developed without introducing Legendre moments of the dependent variable higher than the zeroth moment. Numerical comparisons of the new method with the second order NIM, the upwind difference scheme (UWDS) and the locally exact consistent upwind scheme of second order (LECUSSO) showed that, in the important 1% error range, the new method is more efficient than the UWDS, and the LECUSSO scheme, but, less efficient than the second order NIM. Also two new methods for solving the generic, two-dimensional, time-dependent, convection-diffusion equation were developed. One is a full space-time NIM in which both the spatial and temporal operators are discretized using the nodal integral approach. The other is a hybrid finite-difference/NIM method in which the temporal operator is discretized using a backward finite-difference approximation, and the spatial operator is discretized using the nodal integral approach. It was found, as expected, that the full space-time NIM is second order in both space and time while the hybrid finite-difference/NIM is second order in space but only first order in time. Finally, two new methods for solving the conservation of mass and the Navier-Stokes equations for incompressible fluid flow were developed. One is for the steady-state mass and Navier-Stokes equations while the other solves the time-dependent equations. The spatial stencils that result from these new formulations for the mass and the Navier-Stokes equations are similar to those obtained by traditional staggered-grid finite-difference methods. However, the new methods use second order approximations for both the velocities and the pressures. These
Multifractal Analysis for the Teichmueller Flow
Energy Technology Data Exchange (ETDEWEB)
Meson, Alejandro M., E-mail: meson@iflysib.unlp.edu.ar; Vericat, Fernando, E-mail: vericat@iflysib.unlp.edu.ar [Instituto de Fisica de Liquidos y Sistemas Biologicos (IFLYSIB) CCT-CONICET, La Plata-UNLP and Grupo de Aplicaciones Matematicas y Estadisticas de la Facultad de Ingenieria (GAMEFI) UNLP (Argentina)
2012-03-15
We present a multifractal description for Teichmueller flows. A key ingredient to do this is the Rauzy-Veech-Zorich reduction theory, which allows to treat the problem in the setting of suspension flows over subshifts. To perform the multifractal analysis we implement a thermodynamic formalism for suspension flows over countable alphabet subshifts a bit different from that developed by Barreira and Iommi.
Institute of Scientific and Technical Information of China (English)
施新锋
2012-01-01
Continuous flow analysis method for determination of total nitrogen has been a wide range of applications in the environmental monitoring system, according to the characteristics of the continuous flow analyzer, as well as on the determinate particularity of total nitrogen, the paper summarize quality control ieqnirements of total nitrogen determination with continuous flow analysis method.%连续流动分析测定总氮在环境监测系统得到了广范应用，本文根据连续流动分析仪的特点以及在测定总氮项目上的特殊性，归纳总结了连续流动分析测定总氮的质量控制要求。
Subchannel analysis with flow blockages
Sabotinov, L.
1985-05-01
The steady state single-phase three-dimensional flow in the rod bundle geometry of a nuclear pressurized water reactor was calculated with the PHOENICS 84 program. Flow blockages, which may occur under accident conditions, are simulated. Results show that PHOENICS-84 can be applied to calculation of the three-dimensional fields of velocities in fuel rod bundles containing complete flow blockages in cells. The code can treat recirculation zones.
Cluster analysis of multiple planetary flow regimes
Mo, Kingtse; Ghil, Michael
1988-01-01
A modified cluster analysis method developed for the classification of quasi-stationary events into a few planetary flow regimes and for the examination of transitions between these regimes is described. The method was applied first to a simple deterministic model and then to a 500-mbar data set for Northern Hemisphere (NH), for which cluster analysis was carried out in the subspace of the first seven empirical orthogonal functions (EOFs). Stationary clusters were found in the low-frequency band of more than 10 days, while transient clusters were found in the band-pass frequency window between 2.5 and 6 days. In the low-frequency band, three pairs of clusters determined EOFs 1, 2, and 3, respectively; they exhibited well-known regional features, such as blocking, the Pacific/North American pattern, and wave trains. Both model and low-pass data exhibited strong bimodality.
GENERALIZED VARIATIONAL OPTIMAZATION ANALYSIS FOR 2-D FLOW FIELD
Institute of Scientific and Technical Information of China (English)
HUANG Si-xun; XU Ding-hua; LAN Wei-ren; TENG Jia-jun
2005-01-01
The Variational Optimization Analysis Method (VOAM) for 2-D flow field suggested by Sasaki was reviewed first. It is known that the VOAM can be used efficiently in most cases. However, in the cases where there are high frequency noises in 2-D flow field, it appears to be inefficient. In the present paper, based on Sasaki's VOAM, a Generalized Variational Optimization Analysis Method (GVOAM) was proposed with regularization ideas, which could deal well with flow fields containing high frequency noises. A numerical test shows that observational data can be both variationally optimized and filtered, and therefore the GVOAM is an efficient method.
ANALYSIS AND ACCOUNTING OF TOTAL CASH FLOW
Directory of Open Access Journals (Sweden)
MELANIA ELENA MICULEAC
2012-01-01
Full Text Available In order to reach the objective of supplying some relevant information regarding the liquidity inflows and outflows during a financial exercise, the total cash flow analysis must include the analysis of result cashable from operation, of payments and receipts related to the investment and of financing decisions of the last exercise, as well as the analysis of treasury variation (of cash items. The management of total cash flows ensures the correlation of current liquidness flows as consequence of receipts with the payments ’flows, in order to provide payment continuity of mature obligations.
Fractal analysis of flow of the river Warta
Radziejewski, Maciej; Kundzewicz, Zbigniew W.
1997-12-01
A long time series (170 years) of daily flows of the river Warta (Poland) are subject to fractal analysis. A binary variable (renewal stream) illustrating excursions of the process of flow is examined. The raw series is subject to de-seasonalization and normalization. Fractal dimensions of crossings of Warta flows are determined using a novel variant of the box-counting method. Temporal variability of the flow process is studied by determination of fractal dimensions for shifted horizons of 10 or 30 years length. Spectral properties are compared between the time series of flows, and the fractional Brownian motion which describes both the fractal structure of the process and the Hurst phenomenon. The approach may be useful in further studies of non-stationary of the process of flow, analysis of extreme hydrological events and synthetic flow generation.
ANALYSIS AND ACCOUNTING OF TOTAL CASH FLOW
National Research Council Canada - National Science Library
MELANIA ELENA MICULEAC
2012-01-01
In order to reach the objective of supplying some relevant information regarding the liquidity inflows and outflows during a financial exercise, the total cash flow analysis must include the analysis...
Basic Functional Analysis Puzzles of Spectral Flow
DEFF Research Database (Denmark)
Booss-Bavnbek, Bernhelm
2011-01-01
We explain an array of basic functional analysis puzzles on the way to general spectral flow formulae and indicate a direction of future topological research for dealing with these puzzles.......We explain an array of basic functional analysis puzzles on the way to general spectral flow formulae and indicate a direction of future topological research for dealing with these puzzles....
Time-derivative preconditioning method for multicomponent flow
Housman, Jeffrey Allen
A time-derivative preconditioned system of equations suitable for the numerical simulation of single component and multicomponent inviscid flows at all speeds is formulated. The system is shown to be hyperbolic in time and remain well-posed at low Mach numbers, allowing an efficient time marching solution strategy to be utilized from transonic to incompressible flow speeds. For multicomponent flow at low speed, a preconditioned nonconservative discretization scheme is described which preserves pressure and velocity equilibrium across fluid interfaces, handles sharp liquid/gas interfaces with large density ratios, while remaining well-conditioned for time marching methods. The method is then extended to transonic and supersonic flows using a hybrid conservative/nonconservative formulation which retains the pressure/velocity equilibrium property and converges to the correct weak solution when shocks are present. In order to apply the proposed model to complex flow applications, the overset grid methodology is used where the equations are transformed to a nonorthogonal curvilinear coordinate system and discretized on structured body-fitted curvilinear grids. The multicomponent model and its extension to homogeneous multiphase mixtures is discussed and the hyperbolicity of the governing equations is demonstrated. Low Mach number perturbation analysis is then performed on the system of equations and a local time-derivative preconditioning matrix is derived allowing time marching numerical methods to remain efficient at low speeds. Next, a particular time marching numerical method is presented along with three discretization schemes for the convective terms. These include a conservative preconditioned Roe type method, a nonconservative preconditioned Split Coefficient Matrix (SCM) method, and hybrid formulation which combines the conservative and nonconservative schemes using a simple switching function. A characteristic boundary treatment which includes time
Flow “Fine” Synthesis: High Yielding and Selective Organic Synthesis by Flow Methods
2015-01-01
Abstract The concept of flow “fine” synthesis, that is, high yielding and selective organic synthesis by flow methods, is described. Some examples of flow “fine” synthesis of natural products and APIs are discussed. Flow methods have several advantages over batch methods in terms of environmental compatibility, efficiency, and safety. However, synthesis by flow methods is more difficult than synthesis by batch methods. Indeed, it has been considered that synthesis by flow methods can be applicable for the production of simple gasses but that it is difficult to apply to the synthesis of complex molecules such as natural products and APIs. Therefore, organic synthesis of such complex molecules has been conducted by batch methods. On the other hand, syntheses and reactions that attain high yields and high selectivities by flow methods are increasingly reported. Flow methods are leading candidates for the next generation of manufacturing methods that can mitigate environmental concerns toward sustainable society. PMID:26337828
Jang, Jaeseong; Ahn, Chi Young; Jeon, Kiwan; Choi, Jung-il; Lee, Changhoon; Seo, Jin Keun
2015-03-01
A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color Doppler echocardiography measurement. From 3D incompressible Navier- Stokes equation, a 2D incompressible Navier-Stokes equation with a mass source term is derived to utilize the measurable color flow ultrasound data in a plane along with the moving boundary condition. The proposed model reflects out-of-plane blood flows on the imaging plane through the mass source term. For demonstrating a feasibility of the proposed method, we have performed numerical simulations of the forward problem and numerical analysis of the reconstruction method. First, we construct a 3D moving LV region having a specific stroke volume. To obtain synthetic intra-ventricular flows, we performed a numerical simulation of the forward problem of Navier-Stokes equation inside the 3D moving LV, computed 3D intra-ventricular velocity fields as a solution of the forward problem, projected the 3D velocity fields on the imaging plane and took the inner product of the 2D velocity fields on the imaging plane and scanline directional velocity fields for synthetic scanline directional projected velocity at each position. The proposed method utilized the 2D synthetic projected velocity data for reconstructing LV blood flow. By computing the difference between synthetic flow and reconstructed flow fields, we obtained the averaged point-wise errors of 0.06 m/s and 0.02 m/s for u- and v-components, respectively.
Content analysis in information flows
Energy Technology Data Exchange (ETDEWEB)
Grusho, Alexander A. [Institute of Informatics Problems of Federal Research Center “Computer Science and Control” of the Russian Academy of Sciences, Vavilova str., 44/2, Moscow (Russian Federation); Faculty of Computational Mathematics and Cybernetics, Moscow State University, Moscow (Russian Federation); Grusho, Nick A.; Timonina, Elena E. [Institute of Informatics Problems of Federal Research Center “Computer Science and Control” of the Russian Academy of Sciences, Vavilova str., 44/2, Moscow (Russian Federation)
2016-06-08
The paper deals with architecture of content recognition system. To analyze the problem the stochastic model of content recognition in information flows was built. We proved that under certain conditions it is possible to solve correctly a part of the problem with probability 1, viewing a finite section of the information flow. That means that good architecture consists of two steps. The first step determines correctly certain subsets of contents, while the second step may demand much more time for true decision.
Totally Coded Method for Signal Flow Graph Algorithm
Institute of Scientific and Technical Information of China (English)
XU Jing-bo; ZHOU Mei-hua
2002-01-01
After a code-table has been established by means of node association information from signal flow graph, the totally coded method (TCM) is applied merely in the domain of code operation beyond any figure-earching algorithm. The code-series (CS) have the holoinformation nature, so that both the content and the sign of each gain- term can be determined via the coded method. The principle of this method is simple and it is suited for computer programming. The capability of the computer-aided analysis for switched current network(SIN) can be enhanced.
Lattice Boltzmann method for linear oscillatory noncontinuum flows.
Shi, Yong; Yap, Ying Wan; Sader, John E
2014-03-01
Oscillatory gas flows are commonly generated by micro- and nanoelectromechanical systems. Due to their small size and high operating frequencies, these devices often produce noncontinuum gas flows. Theoretical analysis of such flows requires solution of the unsteady Boltzmann equation, which can present a formidable challenge. In this article, we explore the applicability of the lattice Boltzmann (LB) method to such linear oscillatory noncontinuum flows; this method is derived from the linearized Boltzmann Bhatnagar-Gross-Krook (BGK) equation. We formulate four linearized LB models in the frequency domain, based on Gaussian-Hermite quadratures of different algebraic precision (AP). The performance of each model is assessed by comparison to high-accuracy numerical solutions to the linearized Boltzmann-BGK equation for oscillatory Couette flow. The numerical results demonstrate that high even-order LB models provide superior performance over the greatest noncontinuum range. Our results also highlight intrinsic deficiencies in the current LB framework, which is incapable of capturing noncontinuum behavior at high oscillation frequencies, regardless of quadrature AP and the Knudsen number.
Lattice Boltzmann method for linear oscillatory noncontinuum flows
Shi, Yong; Yap, Ying Wan; Sader, John E.
2014-03-01
Oscillatory gas flows are commonly generated by micro- and nanoelectromechanical systems. Due to their small size and high operating frequencies, these devices often produce noncontinuum gas flows. Theoretical analysis of such flows requires solution of the unsteady Boltzmann equation, which can present a formidable challenge. In this article, we explore the applicability of the lattice Boltzmann (LB) method to such linear oscillatory noncontinuum flows; this method is derived from the linearized Boltzmann Bhatnagar-Gross-Krook (BGK) equation. We formulate four linearized LB models in the frequency domain, based on Gaussian-Hermite quadratures of different algebraic precision (AP). The performance of each model is assessed by comparison to high-accuracy numerical solutions to the linearized Boltzmann-BGK equation for oscillatory Couette flow. The numerical results demonstrate that high even-order LB models provide superior performance over the greatest noncontinuum range. Our results also highlight intrinsic deficiencies in the current LB framework, which is incapable of capturing noncontinuum behavior at high oscillation frequencies, regardless of quadrature AP and the Knudsen number.
Robust-mode analysis of hydrodynamic flows
Roy, Sukesh; Gord, James R.; Hua, Jia-Chen; Gunaratne, Gemunu H.
2017-04-01
The emergence of techniques to extract high-frequency high-resolution data introduces a new avenue for modal decomposition to assess the underlying dynamics, especially of complex flows. However, this task requires the differentiation of robust, repeatable flow constituents from noise and other irregular features of a flow. Traditional approaches involving low-pass filtering and principle components analysis have shortcomings. The approach outlined here, referred to as robust-mode analysis, is based on Koopman decomposition. Three applications to (a) a counter-rotating cellular flame state, (b) variations in financial markets, and (c) turbulent injector flows are provided.
Gradual Variation Analysis for Groundwater Flow
Chen, Li
2010-01-01
Groundwater flow in Washington DC greatly influences the surface water quality in urban areas. The current methods of flow estimation, based on Darcy's Law and the groundwater flow equation, can be described by the diffusion equation (the transient flow) and the Laplace equation (the steady-state flow). The Laplace equation is a simplification of the diffusion equation under the condition that the aquifer has a recharging boundary. The practical way of calculation is to use numerical methods to solve these equations. The most popular system is called MODFLOW, which was developed by USGS. MODFLOW is based on the finite-difference method in rectangular Cartesian coordinates. MODFLOW can be viewed as a "quasi 3D" simulation since it only deals with the vertical average (no z-direction derivative). Flow calculations between the 2D horizontal layers use the concept of leakage. In this project, we have established a mathematical model based on gradually varied functions for groundwater data volume reconstruction. T...
An application of numerical methods to the prediction of strata methane flow in longwall mining
Ediz, I.G.
1991-01-01
This research describes an application of numerical methods for the prediction of strata methane flow into mine workings around a longwall coal face employing methane drainage. This method of methane prediction was developed by solving the time-dependent gas flow equation using the finite element analysis. Having obtained the gas pressure distribution throughout the finite element mesh, a mass flow equation was derived to calculate methane flow rate for a given mining boundary. A computer pro...
Computational methods for internal flows with emphasis on turbomachinery
Mcnally, W. D.; Sockol, P. M.
1981-01-01
Current computational methods for analyzing flows in turbomachinery and other related internal propulsion components are presented. The methods are divided into two classes. The inviscid methods deal specifically with turbomachinery applications. Viscous methods, deal with generalized duct flows as well as flows in turbomachinery passages. Inviscid methods are categorized into the potential, stream function, and Euler aproaches. Viscous methods are treated in terms of parabolic, partially parabolic, and elliptic procedures. Various grids used in association with these procedures are also discussed.
Ocular Blood Flow Autoregulation Mechanisms and Methods
Directory of Open Access Journals (Sweden)
Xue Luo
2015-01-01
Full Text Available The main function of ocular blood flow is to supply sufficient oxygen and nutrients to the eye. Local blood vessels resistance regulates overall blood distribution to the eye and can vary rapidly over time depending on ocular need. Under normal conditions, the relation between blood flow and perfusion pressure in the eye is autoregulated. Basically, autoregulation is a capacity to maintain a relatively constant level of blood flow in the presence of changes in ocular perfusion pressure and varied metabolic demand. In addition, ocular blood flow dysregulation has been demonstrated as an independent risk factor to many ocular diseases. For instance, ocular perfusion pressure plays key role in the progression of retinopathy such as glaucoma and diabetic retinopathy. In this review, different direct and indirect techniques to measure ocular blood flow and the effect of myogenic and neurogenic mechanisms on ocular blood flow are discussed. Moreover, ocular blood flow regulation in ocular disease will be described.
Methods of Multivariate Analysis
Rencher, Alvin C
2012-01-01
Praise for the Second Edition "This book is a systematic, well-written, well-organized text on multivariate analysis packed with intuition and insight . . . There is much practical wisdom in this book that is hard to find elsewhere."-IIE Transactions Filled with new and timely content, Methods of Multivariate Analysis, Third Edition provides examples and exercises based on more than sixty real data sets from a wide variety of scientific fields. It takes a "methods" approach to the subject, placing an emphasis on how students and practitioners can employ multivariate analysis in real-life sit
A Virtual Branch Method for Branch Power Flow Off-limit Analysis%支路潮流越限控制的虚拟支路法
Institute of Scientific and Technical Information of China (English)
苗峰显; 白雪峰; 郭志忠
2009-01-01
为解决支路潮流越限问题,提出了支路潮流越限控制的虚拟支路法.通过对潮流越限支路并联虚拟支路法,使原潮流越限支路的电流降低到目标电流水平.虚拟支路导纳参数由目标分流系数、潮流越限支路导纳及戴维南等效阻抗共同确定.基于置换定理,将虚拟支路用含参数的虚拟功率源置换,将虚拟支路的切除问题转化为虚拟支路两端点注入功率的增长问题.根据支路视在功率对节点功率的灵敏度,逐步计算最小代价的控制方案.IEEE算例仿真显示该方法可将越限支路电流降低到目标电流水平,验证了其可行性和有效性.%A virtual branch control method is proposed to solve the branch power flow off-limit problem. By adding a shunt virtual branch to the branch experiencing branch power flow off-limit, the original off-limit current of the branch can be reduced to a target level of branch current. The admittance of the virtual branch can be obtained by target shunting coefficient,Thevenin's equivalent impedance and admittance of the branch of power flow off-limit. Based on substitution theorem, the virtual branch is replaced by a parameterized virtual power source. Thus, the remove problem of virtual branch is turned to injection power increase problem on the two buses connected by the virtual branch. Based on sensitivity of the apparent power of the branch with respect to bus injection power, the minimum cost control scheme for branch of power flow off-limit can be obtained. The simulation results of the New England 39-bus test system show that the current of the branch of power flow off-limit descends to target level of current. The feasibility and efficiency of the proposed algorithm are validated.
An efficient method for enumerating oral spirochetes using flow cytometry.
Orth, Rebecca; O'Brien-Simpson, Neil; Dashper, Stuart; Walsh, Katrina; Reynolds, Eric
2010-02-01
Spirochetes, such as Treponema denticola, are thin walled, helical, motile bacteria. They are notoriously difficult to enumerate due to their thinness and the difficulties associated with culturing them. Here we have developed a modified oral bacterial growth medium (OBGM) that significantly improves the cultivation of T. denticola compared with a previously published growth medium. Three methods for the enumeration of T. denticola, semi-solid growth medium colony-forming unit (CFU) counts, DNA analysis and flow cytometry, are described and compared. Enumeration of T. denticola using the semi-solid agar method resulted in a positive linear relationship with absorbance of the culture (R(2)=0.9423). However, the semi-solid agar method was found to consistently underestimate (by 50 fold) the T. denticola cell density compared to previously published data. DNA analysis of T. denticola cultures reliably and consistently resulted in a positive linear relationship with absorbance (R(2)=0.9360), giving a calculated cell density of 6.9 x 10(8)cells/mL at an absorbance of 0.2 at 650 nm. Flow cytometry was also found to result in a positive linear relationship with absorbance (R(2)=0.9874), giving a calculated cell density of 6.6 x 10(8)cells/mL at an absorbance of 0.2 at 650 nm. In comparing all of these enumeration methods, the flow cytometry method was found to have distinct advantages, as it is accurate, rapid, and could distinguish between live and dead bacteria. Thus flow cytometry is a recommended means for the rapid and reliable enumeration of viable spirochetes from culture.
Analysis of Cortical Flow Models In Vivo
Benink, Hélène A.; Mandato, Craig A.; Bement, William M.
2000-01-01
Cortical flow, the directed movement of cortical F-actin and cortical organelles, is a basic cellular motility process. Microtubules are thought to somehow direct cortical flow, but whether they do so by stimulating or inhibiting contraction of the cortical actin cytoskeleton is the subject of debate. Treatment of Xenopus oocytes with phorbol 12-myristate 13-acetate (PMA) triggers cortical flow toward the animal pole of the oocyte; this flow is suppressed by microtubules. To determine how this suppression occurs and whether it can control the direction of cortical flow, oocytes were subjected to localized manipulation of either the contractile stimulus (PMA) or microtubules. Localized PMA application resulted in redirection of cortical flow toward the site of application, as judged by movement of cortical pigment granules, cortical F-actin, and cortical myosin-2A. Such redirected flow was accelerated by microtubule depolymerization, showing that the suppression of cortical flow by microtubules is independent of the direction of flow. Direct observation of cortical F-actin by time-lapse confocal analysis in combination with photobleaching showed that cortical flow is driven by contraction of the cortical F-actin network and that microtubules suppress this contraction. The oocyte germinal vesicle serves as a microtubule organizing center in Xenopus oocytes; experimental displacement of the germinal vesicle toward the animal pole resulted in localized flow away from the animal pole. The results show that 1) cortical flow is directed toward areas of localized contraction of the cortical F-actin cytoskeleton; 2) microtubules suppress cortical flow by inhibiting contraction of the cortical F-actin cytoskeleton; and 3) localized, microtubule-dependent suppression of actomyosin-based contraction can control the direction of cortical flow. We discuss these findings in light of current models of cortical flow. PMID:10930453
Application of vector finite volume method for electromagnetic flow simulation
Energy Technology Data Exchange (ETDEWEB)
Takata, T.; Murashige, R.; Matsumoto, T.; Yamaguchi, A. [Osaka Univ., Suita, Osaka (Japan)
2011-07-01
A vector finite volume method (VFVM) has been developed for an electromagnetic flow analysis. In the VFVM, the governing equations of magnetic flux density and electric field intensity are solved separately so as to reduce the computational cost caused by an iterative procedure that is required to satisfy the solenoidal condition. In the present paper, a suppression of temperature fluctuation of liquid sodium after a T-junction has also been investigated with a simplified two dimensional numerical analysis by adding an obstacle (turbulence promoter) or a magnetic field after the junction. (author)
Ocular Blood Flow Autoregulation Mechanisms and Methods
Xue Luo; Yu-meng Shen; Meng-nan Jiang; Xiang-feng Lou; Yin Shen
2015-01-01
The main function of ocular blood flow is to supply sufficient oxygen and nutrients to the eye. Local blood vessels resistance regulates overall blood distribution to the eye and can vary rapidly over time depending on ocular need. Under normal conditions, the relation between blood flow and perfusion pressure in the eye is autoregulated. Basically, autoregulation is a capacity to maintain a relatively constant level of blood flow in the presence of changes in ocular perfusion pressure and va...
Flow visualisation of downhill skiers using the lattice Boltzmann method
Asai, Takeshi; Hong, Sungchan; Ijuin, Koichi
2017-03-01
In downhill alpine skiing, skiers often exceed speeds of 120 km h-1, with air resistance substantially affecting the overall race times. To date, studies on air resistance in alpine skiing have used wind tunnels and actual skiers to examine the relationship between the gliding posture and magnitude of drag and for the design of skiing equipment. However, these studies have not revealed the flow velocity distribution and vortex structure around the skier. In the present study, computational fluid dynamics are employed with the lattice Boltzmann method to derive the relationship between total drag and the flow velocity around a downhill skier in the full-tuck position. Furthermore, the flow around the downhill skier is visualised, and its vortex structure is examined. The results show that the total drag force in the downhill skier model is 27.0 N at a flow velocity of 15 m s-1, increasing to 185.8 N at 40 m s-1. From analysis of the drag distribution and the flow profile, the head, upper arms, lower legs, and thighs (including buttocks) are identified as the major sources of drag on a downhill skier. Based on these results, the design of suits and equipment for reducing the drag from each location should be the focus of research and development in ski equipment. This paper describes a pilot study that introduces undergraduate students of physics or engineering into this research field. The results of this study are easy to understand for undergraduate students.
Aggarwal, Srijan; Jeon, Youchul; Hozalski, Raymond M
2015-09-01
Assimilable organic carbon (AOC) is one of the major determinants of microbial growth and stability in drinking water distribution systems. Nevertheless, AOC measurements are rarely conducted in practice owing, in part, to the tedious and time-consuming nature of the bioassay. Herein, we compared three alternative cell count approaches [flow cytometry with staining (FC-S), flow cytometry without staining (FC-NS), and particle counting (Coulter counter; CC)] for bacterial enumeration as a means to expedite the AOC bioassay. Our results suggest that of the three methods only FC-S provides a suitable alternative to plate counting for rapid and accurate enumeration of both P17 and NOX in the AOC bioassay. While the cell counts obtained by FC-NS were linearly correlated with those obtained using the traditional heterotrophic plate count (HPC) method (FC-NS: R(2) = 0.89-0.96), the AOC values obtained by FC-NS were overestimated by 18-57 %. The CC approach was unsuccessful in enumerating Spirillum strain NOX cells because of the relatively small size of that organism. The CC counts were linearly correlated with HPC for Pseudomonas fluorescens strain P-17 (P17) cells (R(2) = 0.83) but like FC-NS, the CC approach also overestimated the AOC values (for P-17). The advantage of the FC-S method over the other two is improved sensitivity and the ability to specifically enumerate whole cells (and likely viable) as opposed to non-viable cells, cell debris, and other contaminating particles introduced by the test water itself or sample handling.
A study of grout flow pattern analysis
Energy Technology Data Exchange (ETDEWEB)
Lee, S. Y. [Savannah River National Lab., Aiken, SC (United States); Hyun, S. [Mercer Univ., Macon, GA (United States)
2013-01-10
A new disposal unit, designated as Salt Disposal Unit no. 6 (SDU6), is being designed for support of site accelerated closure goals and salt nuclear waste projections identified in the new Liquid Waste System plan. The unit is cylindrical disposal vault of 380 ft diameter and 43 ft in height, and it has about 30 million gallons of capacity. Primary objective was to develop the computational model and to perform the evaluations for the flow patterns of grout material in SDU6 as function of elevation of grout discharge port, and slurry rheology. A Bingham plastic model was basically used to represent the grout flow behavior. A two-phase modeling approach was taken to achieve the objective. This approach assumes that the air-grout interface determines the shape of the accumulation mound. The results of this study were used to develop the design guidelines for the discharge ports of the Saltstone feed materials in the SDU6 facility. The focusing areas of the modeling study are to estimate the domain size of the grout materials radially spread on the facility floor under the baseline modeling conditions, to perform the sensitivity analysis with respect to the baseline design and operating conditions such as elevation of discharge port, discharge pipe diameter, and grout properties, and to determine the changes in grout density as it is related to grout drop height. An axi-symmetric two-phase modeling method was used for computational efficiency. Based on the nominal design and operating conditions, a transient computational approach was taken to compute flow fields mainly driven by pumping inertia and natural gravity. Detailed solution methodology and analysis results are discussed here.
A study of grout flow pattern analysis
Energy Technology Data Exchange (ETDEWEB)
Lee, S. Y. [Savannah River National Lab., Aiken, SC (United States); Hyun, S. [Mercer Univ., Macon, GA (United States)
2013-01-10
A new disposal unit, designated as Salt Disposal Unit no. 6 (SDU6), is being designed for support of site accelerated closure goals and salt nuclear waste projections identified in the new Liquid Waste System plan. The unit is cylindrical disposal vault of 380 ft diameter and 43 ft in height, and it has about 30 million gallons of capacity. Primary objective was to develop the computational model and to perform the evaluations for the flow patterns of grout material in SDU6 as function of elevation of grout discharge port, and slurry rheology. A Bingham plastic model was basically used to represent the grout flow behavior. A two-phase modeling approach was taken to achieve the objective. This approach assumes that the air-grout interface determines the shape of the accumulation mound. The results of this study were used to develop the design guidelines for the discharge ports of the Saltstone feed materials in the SDU6 facility. The focusing areas of the modeling study are to estimate the domain size of the grout materials radially spread on the facility floor under the baseline modeling conditions, to perform the sensitivity analysis with respect to the baseline design and operating conditions such as elevation of discharge port, discharge pipe diameter, and grout properties, and to determine the changes in grout density as it is related to grout drop height. An axi-symmetric two-phase modeling method was used for computational efficiency. Based on the nominal design and operating conditions, a transient computational approach was taken to compute flow fields mainly driven by pumping inertia and natural gravity. Detailed solution methodology and analysis results are discussed here.
Ma, Yin-Zhe
2012-01-01
It has been argued recently that the galaxy peculiar velocity field provides evidence of excessive power on scales of $50\\hmpc$, which seems to be inconsistent with the standard $\\Lambda$CDM cosmological model. We discuss several assumptions and conventions used in studies of the large-scale bulk flow to check whether this claim is robust under a variety of conditions. Rather than using a composite catalogue we select samples from the SN, ENEAR, SFI++ and A1SN catalogues, and correct for Malmquist bias in each according to the IRAS PSCz density field. We also use slightly different assumptions about the small-scale velocity dispersion and the parameterisation of the matter power spectrum when calculating the variance of the bulk flow. By combining the likelihood of individual catalogues using a Bayesian hyper-parameter method, we find that the joint likelihood of the amplitude parameter gives $\\sigma_8=0.65^{+0.47}_{-0.35}(\\pm 1 \\sigma)$, which is entirely consistent with the $\\Lambda$CDM model. In addition, ...
On methods of estimating cosmological bulk flows
Nusser, Adi
2015-01-01
We explore similarities and differences between several estimators of the cosmological bulk flow, $\\bf B$, from the observed radial peculiar velocities of galaxies. A distinction is made between two theoretical definitions of $\\bf B$ as a dipole moment of the velocity field weighted by a radial window function. One definition involves the three dimensional (3D) peculiar velocity, while the other is based on its radial component alone. Different methods attempt at inferring $\\bf B$ for either of these definitions which coincide only for a constant velocity field. We focus on the Wiener Filtering (WF, Hoffman et al. 2015) and the Constrained Minimum Variance (CMV,Feldman et al. 2010) methodologies. Both methodologies require a prior expressed in terms of the radial velocity correlation function. Hoffman et al. compute $\\bf B$ in Top-Hat windows from a WF realization of the 3D peculiar velocity field. Feldman et al. infer $\\bf B$ directly from the observed velocities for the second definition of $\\bf B$. The WF ...
Institute of Scientific and Technical Information of China (English)
WANG Su-fen; CANG Ping; FENG Jun-kang; PAN Chen-yin
2010-01-01
Click-streams of online shopping are the tracks/Wails of interactions between a customer and a vendor. We observe that it is of great importance both in theory and practice to explore a deep analysis method for analyzing click-stream information of an individual customer in a specific transaction for understanding the bidirectional value transfer within the machine-human interaction of an online store and for its personalization. We analyze the significance, the hierarchical structure and the characteristics of dick-stream information and propose that Ricoeur's hermeneutic theory be the foumdation of forming such a deep analysis method. Then we use the empirical context information of the click-stream to improve the naive interpretation put forward by Ricoeur. Moreover, we apply the Grounded Theory to extend the deep analysis of Ricoeur's theory of textual interpretation. The improved theory fits well with the needs of interpretation and the analysis of click-stream information. We exemplify and show the feasibility of this analysis method by using data collected (a single case)from a large study of human-computer interaction.
Development of a Wind Turbine Rotor Flow Panel Method
Energy Technology Data Exchange (ETDEWEB)
Van Garrel, A. [ECN Wind Energy, Petten (Netherlands)
2011-12-15
The ongoing trend towards larger wind turbines intensifies the demand for more physically realistic wind turbine rotor aerodynamics models that can predict the detailed transient pressure loadings on the rotor blades better than current engineering models. In this report the mathematical, numerical, and practical aspects of a new wind turbine rotor flow simulation code is described. This wind turbine simulation code is designated ROTORFLOW. In this method the fluid dynamics problem is solved through a boundary integral equation which reduces the problem to the surface of the configuration. The derivation of the integral equations is described as well as the assumptions made to arrive at them starting with the full Navier-Stokes equations. The basic numerical aspects in the solution method are described and a verification study is performed to confirm the validity of the implementation. Example simulations with the code show the flow solutions for a stationary wing and for a rotating wing in yawed conditions. With the ROTORFLOW code developed in this project it is possible to simulate the unsteady flow around wind turbine rotors in yawed conditions and obtain detailed pressure distributions, and thus blade loadings, at the surface of the blades. General rotor blade geometries can be handled, opening the way to the detailed flow analysis of winglets, partial span flaps, swept blade tips, etc. The ROTORFLOW solver only requires a description of the rotor surface which keeps simulation preparation time short, and makes it feasible to use the solver in the design iteration process.
Morphometric methods for simulation of water flow.
Booltink, H.W.G.
1993-01-01
Water flow in structured soils is strongly governed by the occurence of macropores. In this study emphasis was given to combined research of morphology of water- conducting macropores and soil physical measurements on bypass flow. Main research objectives were to: (i) develop and improve soil physic
Improving Software Systems By Flow Control Analysis
Directory of Open Access Journals (Sweden)
Piotr Poznanski
2012-01-01
Full Text Available Using agile methods during the implementation of the system that meets mission critical requirements can be a real challenge. The change in the system built of dozens or even hundreds of specialized devices with embedded software requires the cooperation of a large group of engineers. This article presents a solution that supports parallel work of groups of system analysts and software developers. Deployment of formal rules to the requirements written in natural language enables using formal analysis of artifacts being a bridge between software and system requirements. Formalism and textual form of requirements allowed the automatic generation of message ﬂow graph for the (sub system, called the “big-picture-model”. Flow diagram analysis helped to avoid a large number of defects whose repair cost in extreme cases could undermine the legitimacy of agile methods in projects of this scale. Retrospectively, a reduction of technical debt was observed. Continuous analysis of the “big picture model” improves the control of the quality parameters of the software architecture. The article also tries to explain why the commercial platform based on UML modeling language may not be suﬃcient in projects of this complexity.
DEFF Research Database (Denmark)
Jørgensen, Ulla Vang; Nielsen, Steffen; Hansen, Elo Harald
1998-01-01
Instigated by developing a flow injection procedure for assay of nitrosyl in concentrated sulphuric acid, different approaches for reliable and robust on-line dilution in FIA were evaluated. These comprised the application of mixing tees in conjunction with mixing coils (including knotted reactors...... approach the criteria stipulated were that the procedure should allow a dilution factor of approximately 100, yet without excessive zone spreading, so that it, on one hand, effectively could eliminate the pronounced Schlieren effect encountered when mixing concentrated sulphuric acid with an aqueous...... in conjunction with knotted reactors of relatively large internal diameter (1.5 mm). The optimized FI-manifold was used with the Griess method for the spectrophotometric assay of nitrosyl (nitrite) in standards prepared in the matrix of concentrated sulphuric acid (detection limit 0.16 mg/l NO+-N (3s...
配电通信网业务断面流量分析方法%An Analysis Method for Business Sectional Flow of Distribution Communication Network
Institute of Scientific and Technical Information of China (English)
何清素; 曾令康; 欧清海; 蒋梨花; 汪晓岩
2014-01-01
The definition of the distribution communications network is presented along with the distribution communication network physical composition and its importance in power system communication.By analyzing the distribution communication network undertaking the principal transactions and their characteristics,a model for the distribution communication business section is proposed.By analyzing the flow calculating method of different business cross-sections,the traffic bandwidth calculation basis is provided to a variety of types of sites and different distribution partitions.The A+ regional electricity distribution business flows is taken as an example to show how the business flow and its calculation is analyzed in accordance with the business section model and the business flow calculation method.Finally,the total traffic of different regions of the distribution automation business is given for reference by network communication planning and design.The sectional flow model provides intelligent electricity distribution network communication with effective means of assessing technical type options,bandwidth forecasting,planning and design,contributing to planning and construction of the power system of both prefectural and municipal backbone distribution communication networks. This work is supported by National High Technology Research and Development Program of China (863 Program) (No.2011AA05A116).%阐述了配电通信网的物理定义、组成及其重要性，分析了配电通信网承载主要业务及业务特点，提出了配电通信业务断面模型，通过分析不同业务断面的流量计算方法，为各种站点类型、不同配电分区中的流量带宽计算提供依据。文中以A+区域配电业务流量计算为例，根据业务断面模型、业务流量计算方法，分析业务流量及流量计算；最后给出不同区域配电自动化业务汇总流量，为配电通信网规划、设计提供参考。断面流量模型可以
DOUBLE METHOD OF CHARACTERISTICS TO ANALYZE HYDRAULIC-THERMAL TRANSIENTS OF PIPELINE FLOW
Institute of Scientific and Technical Information of China (English)
邓松圣; 周明来; 蒲家宁
2002-01-01
The hydraulic and thermal transients in pipeline flow were studied. The method of characteristics for hydraulic transient analysis of batch transport of pipeline flow had been improved. The thermal transient equation, in which the term with v3 was involved, had been inferred, while the corresponding method of characteristics was constructed. The double method of characteristics, which can be used to study the coherent hydraulic-thermal transients of batch transport of pipeline flow, was developed.
Isaacson, Eugene
1994-01-01
This excellent text for advanced undergraduates and graduate students covers norms, numerical solution of linear systems and matrix factoring, iterative solutions of nonlinear equations, eigenvalues and eigenvectors, polynomial approximation, and other topics. It offers a careful analysis and stresses techniques for developing new methods, plus many examples and problems. 1966 edition.
PDF methods for turbulent reactive flows
Hsu, Andrew T.
1995-01-01
Viewgraphs are presented on computation of turbulent combustion, governing equations, closure problem, PDF modeling of turbulent reactive flows, validation cases, current projects, and collaboration with industry and technology transfer.
Field methods for measuring concentrated flow erosion
Castillo, C.; Pérez, R.; James, M. R.; Quinton, J. N.; Taguas, E. V.; Gómez, J. A.
2012-04-01
techniques (3D) for measuring erosion from concentrated flow (pole, laser profilemeter, photo-reconstruction and terrestrial LiDAR) The comparison between two- and three-dimensional methods has showed the superiority of the 3D techniques for obtaining accurate cross sectional data. The results from commonly-used 2D methods can be subject to systematic errors in areal cross section that exceed magnitudes of 10 % on average. In particular, the pole simplified method has showed a clear tendency to understimate areas. Laser profilemeter results show that further research on calibrating optical devices for a variety of soil conditions must be carried out to improve its performance. For volume estimations, photo-reconstruction results provided an excellent approximation to terrestrial laser data and demonstrate that this new remote sensing technique has a promising application field in soil erosion studies. 2D approaches involved important errors even over short measurement distances. However, as well as accuracy, the cost and time requirements of a technique must be considered.
Lagrangian transported MDF methods for compressible high speed flows
Gerlinger, Peter
2017-06-01
This paper deals with the application of thermochemical Lagrangian MDF (mass density function) methods for compressible sub- and supersonic RANS (Reynolds Averaged Navier-Stokes) simulations. A new approach to treat molecular transport is presented. This technique on the one hand ensures numerical stability of the particle solver in laminar regions of the flow field (e.g. in the viscous sublayer) and on the other hand takes differential diffusion into account. It is shown in a detailed analysis, that the new method correctly predicts first and second-order moments on the basis of conventional modeling approaches. Moreover, a number of challenges for MDF particle methods in high speed flows is discussed, e.g. high cell aspect ratio grids close to solid walls, wall heat transfer, shock resolution, and problems from statistical noise which may cause artificial shock systems in supersonic flows. A Mach 2 supersonic mixing channel with multiple shock reflection and a model rocket combustor simulation demonstrate the eligibility of this technique to practical applications. Both test cases are simulated successfully for the first time with a hybrid finite-volume (FV)/Lagrangian particle solver (PS).
Research on stochastic power-flow study methods. Final report
Energy Technology Data Exchange (ETDEWEB)
Heydt, G. T. [ed.
1981-01-01
A general algorithm to determine the effects of uncertainty in bus load and generation on the output of conventional power flow analysis is presented. The use of statistical moments is presented and developed as a means for representing the stochastic process. Statistical moments are used to describe the uncertainties, and facilitate the calculations of single and multivarlate probability density functions of input and output variables. The transformation of the uncertainty through the power flow equations is made by the expansion of the node equations in a multivariate Taylor series about an expected operating point. The series is truncated after the second order terms. Since the power flow equations are nonlinear, the expected values of output quantities is in general not the solution to the conventional load flow problem using expected values of input quantities. The second order transformation offers a correction vector and allows the consideration of larger uncertainties which have caused significant error in the current linear transformation algorithms. Voltage controlled busses are included with consideration of upper and lower limits. The finite reactive power available at generation sites, and fixed ranges of transformer tap movement may have a significant effect on voltage and line power flow statistics. A method is given which considers limitation constraints in the evaluation of all output quantities. The bus voltages, line power flows, transformer taps, and generator reactive power requirements are described by their statistical moments. Their values are expressed in terms of the probability that they are above or below specified limits, and their expected values given that they do fall outside the limits. Thus the algorithm supplies information about severity of overload as well as probability of occurrence. An example is given for an eleven bus system, evaluating each quantity separately. The results are compared with Monte Carlo simulation.
Signal-flow graphs in coupled laser resonator analysis
DEFF Research Database (Denmark)
Pedersen, Christian; Skettrup, Torben
1997-01-01
Signal-flow graph analysis of coupled linear systems is introduced in order to find a simple method to treat systems of coupled optical resonators. The proposed method turns out to be well suited for this purpose, and the reflectance and transmittance of coupled resonator systems are easily found...
Path planning in uncertain flow fields using ensemble method
Wang, Tong; Le Maître, Olivier P.; Hoteit, Ibrahim; Knio, Omar M.
2016-10-01
An ensemble-based approach is developed to conduct optimal path planning in unsteady ocean currents under uncertainty. We focus our attention on two-dimensional steady and unsteady uncertain flows, and adopt a sampling methodology that is well suited to operational forecasts, where an ensemble of deterministic predictions is used to model and quantify uncertainty. In an operational setting, much about dynamics, topography, and forcing of the ocean environment is uncertain. To address this uncertainty, the flow field is parametrized using a finite number of independent canonical random variables with known densities, and the ensemble is generated by sampling these variables. For each of the resulting realizations of the uncertain current field, we predict the path that minimizes the travel time by solving a boundary value problem (BVP), based on the Pontryagin maximum principle. A family of backward-in-time trajectories starting at the end position is used to generate suitable initial values for the BVP solver. This allows us to examine and analyze the performance of the sampling strategy and to develop insight into extensions dealing with general circulation ocean models. In particular, the ensemble method enables us to perform a statistical analysis of travel times and consequently develop a path planning approach that accounts for these statistics. The proposed methodology is tested for a number of scenarios. We first validate our algorithms by reproducing simple canonical solutions, and then demonstrate our approach in more complex flow fields, including idealized, steady and unsteady double-gyre flows.
Path planning in uncertain flow fields using ensemble method
Wang, Tong
2016-08-20
An ensemble-based approach is developed to conduct optimal path planning in unsteady ocean currents under uncertainty. We focus our attention on two-dimensional steady and unsteady uncertain flows, and adopt a sampling methodology that is well suited to operational forecasts, where an ensemble of deterministic predictions is used to model and quantify uncertainty. In an operational setting, much about dynamics, topography, and forcing of the ocean environment is uncertain. To address this uncertainty, the flow field is parametrized using a finite number of independent canonical random variables with known densities, and the ensemble is generated by sampling these variables. For each of the resulting realizations of the uncertain current field, we predict the path that minimizes the travel time by solving a boundary value problem (BVP), based on the Pontryagin maximum principle. A family of backward-in-time trajectories starting at the end position is used to generate suitable initial values for the BVP solver. This allows us to examine and analyze the performance of the sampling strategy and to develop insight into extensions dealing with general circulation ocean models. In particular, the ensemble method enables us to perform a statistical analysis of travel times and consequently develop a path planning approach that accounts for these statistics. The proposed methodology is tested for a number of scenarios. We first validate our algorithms by reproducing simple canonical solutions, and then demonstrate our approach in more complex flow fields, including idealized, steady and unsteady double-gyre flows.
Path planning in uncertain flow fields using ensemble method
Wang, Tong; Le Maître, Olivier P.; Hoteit, Ibrahim; Knio, Omar M.
2016-08-01
An ensemble-based approach is developed to conduct optimal path planning in unsteady ocean currents under uncertainty. We focus our attention on two-dimensional steady and unsteady uncertain flows, and adopt a sampling methodology that is well suited to operational forecasts, where an ensemble of deterministic predictions is used to model and quantify uncertainty. In an operational setting, much about dynamics, topography, and forcing of the ocean environment is uncertain. To address this uncertainty, the flow field is parametrized using a finite number of independent canonical random variables with known densities, and the ensemble is generated by sampling these variables. For each of the resulting realizations of the uncertain current field, we predict the path that minimizes the travel time by solving a boundary value problem (BVP), based on the Pontryagin maximum principle. A family of backward-in-time trajectories starting at the end position is used to generate suitable initial values for the BVP solver. This allows us to examine and analyze the performance of the sampling strategy and to develop insight into extensions dealing with general circulation ocean models. In particular, the ensemble method enables us to perform a statistical analysis of travel times and consequently develop a path planning approach that accounts for these statistics. The proposed methodology is tested for a number of scenarios. We first validate our algorithms by reproducing simple canonical solutions, and then demonstrate our approach in more complex flow fields, including idealized, steady and unsteady double-gyre flows.
Computation of a turbulent channel flow using PDF method
Energy Technology Data Exchange (ETDEWEB)
Minier, J.P. [Electricite de France (EDF), 78 - Chatou (France). Lab. National d`Hydraulique; Pozorski, J. [Polish Academy of Sciences, Gdansk (Poland). Inst. of Fluid-Flow Machinery
1997-05-01
The purpose of the present paper is to present an analysis of a PDF model (Probability Density Function) and an illustration of the possibilities offered by such a method for a high-Reynolds turbulent channel flow. The first part presents the principles of the PDF approach and the introduction of stochastic processes along with a Lagrangian point of view. The model retained is the one put forward by Pope (1991) and includes evolution equations for location, velocity and dissipation of a large number of particles. Wall boundary conditions are then developed for particles. These conditions allow statistical results of the logarithmic region to be correctly reproduced. Simulation of non-homogeneous flows require a pressure-gradient algorithm which is briefly described. Developments are validated by analysing numerical predictions with respect to Comte Bellot experimental data (1965) on a channel flow. This example illustrates the ability of the approach to simulate wall-bounded flows and to provide detailed information such as skewness and flatness factors. (author) 9 refs.
Frontier in nanoscale flows fractional calculus and analytical methods
Lewis, Roland; Liu, Hong-yan
2014-01-01
This ebook covers the basic properties of nanoscale flows, and various analytical and numerical methods for nanoscale flows and environmental flows. This ebook is a good reference not only for audience of the journal, but also for various communities in mathematics, nanotechnology and environmental science.
Control Flow Analysis for BioAmbients
DEFF Research Database (Denmark)
Nielson, Flemming; Nielson, Hanne Riis; Priami, C.
2007-01-01
This paper presents a static analysis for investigating properties of biological systems specified in BioAmbients. We exploit the control flow analysis to decode the bindings of variables induced by communications and to build a relation of the ambients that can interact with each other. We...
The Three Generations of Flow Injection Analysis
DEFF Research Database (Denmark)
Hansen, Elo Harald; Wang, Jianhua
2004-01-01
The characteristics of the three generations of flow injection analysis, that is, FIA, sequential injection analysis (SIA), and bead injection-lab-on-valve (BI-LOV), are briefly outlined, their individual advantages and shortcomings are discussed, and selected practical applications are presented....
Imaging flow cytometry for phytoplankton analysis.
Dashkova, Veronika; Malashenkov, Dmitry; Poulton, Nicole; Vorobjev, Ivan; Barteneva, Natasha S
2017-01-01
This review highlights the concepts and instrumentation of imaging flow cytometry technology and in particular its use for phytoplankton analysis. Imaging flow cytometry, a hybrid technology combining speed and statistical capabilities of flow cytometry with imaging features of microscopy, is rapidly advancing as a cell imaging platform that overcomes many of the limitations of current techniques and contributed significantly to the advancement of phytoplankton analysis in recent years. This review presents the various instrumentation relevant to the field and currently used for assessment of complex phytoplankton communities' composition and abundance, size structure determination, biovolume estimation, detection of harmful algal bloom species, evaluation of viability and metabolic activity and other applications. Also we present our data on viability and metabolic assessment of Aphanizomenon sp. cyanobacteria using Imagestream X Mark II imaging cytometer. Herein, we highlight the immense potential of imaging flow cytometry for microalgal research, but also discuss limitations and future developments.
Two MIS Analysis Methods: An Experimental Comparison.
Wang, Shouhong
1996-01-01
In China, 24 undergraduate business students applied data flow diagrams (DFD) to a mini-case, and 20 used object-oriented analysis (OOA). DFD seemed easier to learn, but after training, those using the OOA method for systems analysis made fewer errors. (SK)
Computational analysis of the flow field downstream of flow conditioners
Energy Technology Data Exchange (ETDEWEB)
Erdal, Asbjoern
1997-12-31
Technological innovations are essential for maintaining the competitiveness for the gas companies and here metering technology is one important area. This thesis shows that computational fluid dynamic techniques can be a valuable tool for examination of several parameters that may affect the performance of a flow conditioner (FC). Previous design methods, such as screen theory, could not provide fundamental understanding of how a FC works. The thesis shows, among other things, that the flow pattern through a complex geometry, like a 19-hole plate FC, can be simulated with good accuracy by a k-{epsilon} turbulence model. The calculations illuminate how variations in pressure drop, overall porosity, grading of porosity across the cross-section and the number of holes affects the performance of FCs. These questions have been studied experimentally by researchers for a long time. Now an understanding of the important mechanisms behind efficient FCs emerges from the predictions. 179 ref., 110 figs., 8 tabs.
Climate Informed Low Flow Frequency Analysis Using Nonstationary Modeling
Liu, D.; Guo, S.; Lian, Y.
2014-12-01
Stationarity is often assumed for frequency analysis of low flows in water resources management and planning. However, many studies have shown that flow characteristics, particularly the frequency spectrum of extreme hydrologic events,were modified by climate change and human activities and the conventional frequency analysis without considering the non-stationary characteristics may lead to costly design. The analysis presented in this paper was based on the more than 100 years of daily flow data from the Yichang gaging station 44 kilometers downstream of the Three Gorges Dam. The Mann-Kendall trend test under the scaling hypothesis showed that the annual low flows had significant monotonic trend, whereas an abrupt change point was identified in 1936 by the Pettitt test. The climate informed low flow frequency analysis and the divided and combined method are employed to account for the impacts from related climate variables and the nonstationarities in annual low flows. Without prior knowledge of the probability density function for the gaging station, six distribution functions including the Generalized Extreme Values (GEV), Pearson Type III, Gumbel, Gamma, Lognormal, and Weibull distributions have been tested to find the best fit, in which the local likelihood method is used to estimate the parameters. Analyses show that GEV had the best fit for the observed low flows. This study has also shown that the climate informed low flow frequency analysis is able to exploit the link between climate indices and low flows, which would account for the dynamic feature for reservoir management and provide more accurate and reliable designs for infrastructure and water supply.
Gravemeier, Volker; Kronbichler, Martin; Gee, Michael W.; Wall, Wolfgang A.
2011-02-01
This article studies three aspects of the recently proposed algebraic variational multiscale-multigrid method for large-eddy simulation of turbulent flow. First, the method is integrated into a second-order-accurate generalized-α time-stepping scheme. Second, a Fourier analysis of a simplified model problem is performed to assess the impact of scale separation on the overall performance of the method. The analysis reveals that scale separation implemented by projective operators provides modeling effects very close to an ideal small-scale subgrid viscosity, that is, it preserves low frequencies, in contrast to non-projective scale separations. Third, the algebraic variational multiscale-multigrid method is applied to turbulent flow past a square-section cylinder. The computational results obtained with the method reveal, on the one hand, the good accuracy achievable for this challenging test case already at a rather coarse discretization and, on the other hand, the superior computing efficiency, e.g., compared to a traditional dynamic Smagorinsky modeling approach.
Liu, Qing
2016-01-01
As a numerically accurate and computationally efficient mesoscopic numerical method, the lattice Boltzmann (LB) method has achieved great success in simulating microscale rarefied gas flows. In this paper, an LB method based on the cascaded collision operator is presented to simulate microchannel gas flows in the transition flow regime. The Bosanquet-type effective viscosity is incorporated into the cascaded lattice Boltzmann (CLB) method to account for the rarefaction effects. In order to gain accurate simulations and match the Bosanquet-type effective viscosity, the combined bounce-back/specular-reflection scheme with a modified second-order slip boundary condition is employed in the CLB method. The present method is applied to study gas flow in a microchannel with periodic boundary condition and gas flow in a long microchannel with pressure boundary condition over a wide range of Knudsen numbers. The predicted results, including the velocity profile, the mass flow rate, and the non-linear pressure deviatio...
Hodograph method in MHD orthogonal fluid flows
Directory of Open Access Journals (Sweden)
P. V. Nguyen
1992-01-01
Full Text Available Equations for steady plane MHD orthogonal flows of a viscous incompressible fluid of finite electrical conductivity are recast in the hodograph plane by using the Legendre transform function of the streamfunction. Three examples are studied to illustrate the developed theory. Solutions and geometries for these examples are determined.
A method of determining combustion gas flow
Bon Tempi, P. J.
1968-01-01
Zirconium oxide coating enables the determination of hot gas flow patterns on liquid rocket injector face and baffle surfaces to indicate modifications that will increase performance and improve combustion stability. The coating withstands combustion temperatures and due to the coarse surface and coloring of the coating, shows the hot gas patterns.
Directory of Open Access Journals (Sweden)
Yasuyuki Nishi
2016-01-01
Full Text Available We proposed a portable and ultra-small axial flow hydraulic turbine that can generate electric power comparatively easily using the low head of open channels such as existing pipe conduits or small rivers. In addition, we proposed a simple design method for axial flow runners in combination with the conventional one-dimensional design method and the design method of axial flow velocity uniformization, with the support of three-dimensional flow analysis. Applying our design method to the runner of an ultra-small axial flow hydraulic turbine, the performance and internal flow of the designed runner were investigated using CFD analysis and experiment (performance test and PIV measurement. As a result, the runners designed with our design method were significantly improved in turbine efficiency compared to the original runner. Specifically, in the experiment, a new design of the runner achieved a turbine efficiency of 0.768. This reason was that the axial component of absolute velocity of the new design of the runner was relatively uniform at the runner outlet in comparison with that of the original runner, and as a result, the negative rotational flow was improved. Thus, the validity of our design method has been verified.
DEFF Research Database (Denmark)
Olivarius, Signe
of the transcriptome, 5’ end capture of RNA is combined with next-generation sequencing for high-throughput quantitative assessment of transcription start sites by two different methods. The methods presented here allow for functional investigation of coding as well as noncoding RNA and contribute to future......While increasing evidence appoints diverse types of RNA as key players in the regulatory networks underlying cellular differentiation and metabolism, the potential functions of thousands of conserved RNA structures encoded in mammalian genomes remain to be determined. Since the functions of most...... RNAs rely on interactions with proteins, the establishment of protein-binding profiles is essential for the characterization of RNAs. Aiming to facilitate RNA analysis, this thesis introduces proteomics- as well as transcriptomics-based methods for the functional characterization of RNA. First, RNA...
Institute of Scientific and Technical Information of China (English)
尤冬石; 刘亚龙; 殷若鹏
2016-01-01
通过对天然气管线输送流量进行优化均衡调度设计，实现对天然气管线运行工况的准确监测。传统方法采用线性时间序列Wolf一步预测方法进行天然气管线输送流量调度，没能有效挖掘天然气管线输送网络中天然气流量的非线性特征，导致调度的准确性不好。提出一种基于定量递归分析的天然气管线输送流量均衡调度方法。首先构建了天然气管线的网络配置结构模型，进行输送流量序列的信号模型构建和非线性时间序列分析，对天然气流量进行相空间重构，在高维相空间中进行递归图构建，实现对天然气管线输送流量的定量递归分析，达到流量准确预测和均衡调度的目的，实现算法改进。仿真实验分析结果表明，采用该方法进行天然气管线输送流量均衡调度，天然气输送运行的工况得到改善，输送配置的均衡性较好，流量预测精度较高，调度效能增强。%Through the optimization of the natural gas pipeline transportation flow to optimize the balanced scheduling design, to achieve an accurate monitoring of the operating conditions of natural gas pipeline. Traditional method using one step prediction method for linear time series Wolf for natural gas pipeline transportation scheduling flow, could not effectively tap nonlinear characteristic of natural gas pipeline to transport gas flow in a network, and lead to the bad accuracy of the scheduling. A natural gas pipeline transportation flow balancing scheduling method based on quantitative recursive analysis is proposed. First construct a network configuration structure model of natural gas pipeline, propose transportation flow sequence signal model construction and nonlinear time series analysis; Next provide the gas flow of phase space reconstruction, recursive graph construction in a high-dimensional phase space, realize recurrence quantification analysis of natural gas pipeline
Methods for estimating flow-duration and annual mean-flow statistics for ungaged streams in Oklahoma
Esralew, Rachel A.; Smith, S. Jerrod
2010-01-01
Flow statistics can be used to provide decision makers with surface-water information needed for activities such as water-supply permitting, flow regulation, and other water rights issues. Flow statistics could be needed at any location along a stream. Most often, streamflow statistics are needed at ungaged sites, where no flow data are available to compute the statistics. Methods are presented in this report for estimating flow-duration and annual mean-flow statistics for ungaged streams in Oklahoma. Flow statistics included the (1) annual (period of record), (2) seasonal (summer-autumn and winter-spring), and (3) 12 monthly duration statistics, including the 20th, 50th, 80th, 90th, and 95th percentile flow exceedances, and the annual mean-flow (mean of daily flows for the period of record). Flow statistics were calculated from daily streamflow information collected from 235 streamflow-gaging stations throughout Oklahoma and areas in adjacent states. A drainage-area ratio method is the preferred method for estimating flow statistics at an ungaged location that is on a stream near a gage. The method generally is reliable only if the drainage-area ratio of the two sites is between 0.5 and 1.5. Regression equations that relate flow statistics to drainage-basin characteristics were developed for the purpose of estimating selected flow-duration and annual mean-flow statistics for ungaged streams that are not near gaging stations on the same stream. Regression equations were developed from flow statistics and drainage-basin characteristics for 113 unregulated gaging stations. Separate regression equations were developed by using U.S. Geological Survey streamflow-gaging stations in regions with similar drainage-basin characteristics. These equations can increase the accuracy of regression equations used for estimating flow-duration and annual mean-flow statistics at ungaged stream locations in Oklahoma. Streamflow-gaging stations were grouped by selected drainage
Numerical method of characteristics for one-dimensional blood flow
Acosta, Sebastian; Riviere, Beatrice; Penny, Daniel J; Rusin, Craig G
2014-01-01
Mathematical modeling at the level of the full cardiovascular system requires the numerical approximation of solutions to a one-dimensional nonlinear hyperbolic system describing flow in a single vessel. This model is often simulated by computationally intensive methods like finite elements and discontinuous Galerkin, while some recent applications require more efficient approaches (e.g. for real-time clinical decision support, phenomena occurring over multiple cardiac cycles, iterative solutions to optimization/inverse problems, and uncertainty quantification). Further, the high speed of pressure waves in blood vessels greatly restricts the time-step needed for stability in explicit schemes. We address both cost and stability by presenting an efficient and unconditionally stable method for approximating solutions to diagonal nonlinear hyperbolic systems. Theoretical analysis of the algorithm is given along with a comparison of our method to a discontinuous Galerkin implementation. Lastly, we demonstrate the ...
Low flow analysis of the lower Drava River
Mijuskovic-Svetinovic, T.; Maricic, S.
2008-11-01
Understanding the regime and the characteristics of low streamflows is of vital importance in several aspects. It is essential for the effective planning, designing, constructing, maintaining, using and managing different water management systems and structures. In addition, frequent running and assessing of estimates of low stream-flow statistics are especially important when different aspects of water quality are considered. This paper attempts to present the results of a stochastic analysis of the River Drava low flow from the gauging station, Donji Miholjac [located at rkm 77+700]. Currently, almost all specialists apply the truncation method in low-flows analysis. Taking this into consideration, it is possible to accept the definition of a low streamflow, as a period when the analysed characteristics are either, equal to or lower than the truncation level of drought. The same method has been applied in this analysis. The calculating method applied takes into account all the essential components of the afore-mentioned process. This includes a number of elements, such as the deficit, duration or the time of the occurrence of low flows, the number of times, the maximum deficit and the maximum duration of the low flows in the analysed time period. Moreover, this paper determines computational values for deficits and for the duration of low flow in different return periods.
Least Squares Shadowing for Sensitivity Analysis of Turbulent Fluid Flows
Blonigan, Patrick; Wang, Qiqi
2014-01-01
Computational methods for sensitivity analysis are invaluable tools for aerodynamics research and engineering design. However, traditional sensitivity analysis methods break down when applied to long-time averaged quantities in turbulent fluid flow fields, specifically those obtained using high-fidelity turbulence simulations. This is because of a number of dynamical properties of turbulent and chaotic fluid flows, most importantly high sensitivity of the initial value problem, popularly known as the "butterfly effect". The recently developed least squares shadowing (LSS) method avoids the issues encountered by traditional sensitivity analysis methods by approximating the "shadow trajectory" in phase space, avoiding the high sensitivity of the initial value problem. The following paper discusses how the least squares problem associated with LSS is solved. Two methods are presented and are demonstrated on a simulation of homogeneous isotropic turbulence and the Kuramoto-Sivashinsky (KS) equation, a 4th order c...
Data flow analysis theory and practice
Khedker, Uday; Sathe, Bageshri
2009-01-01
Data flow analysis is used to discover information for a wide variety of useful applications, ranging from compiler optimizations to software engineering and verification. Modern compilers apply it to produce performance-maximizing code, and software engineers use it to re-engineer or reverse engineer programs and verify the integrity of their programs. Supplementary Online Materials to Strengthen Understanding Unlike most comparable books, many of which are limited to bit vector frameworks and classical constant propagation, Data Flow Analysis: Theory and Practice offers comprehensive covera
Characterization of Vapor and Aerosol Flows by Photothermal Methods.
2014-09-26
TECHNICAL REPORT No. 19 Characterization of Vapor and Aerosol Flows By Photothermal Methods by H. Sontag A. C. Tam IBM Research Laboratory San Jose...PERIOD COVERED Characterization of Vapor and Aerosol Flows Technical Report by Photothermal Methods S. PERFORMING OR. REPORT NUMBER 7. AUTHOR(a) S...related sciences, Montreal, 1985. I. KEY WORDS (Coilnue ..evrevers side II nscoomy ed idontlly by block nu.er) Photothermal , aerosol, flow, spectroscopy
Allocation of Transmission Cost Using Power Flow Tracing Methods
Directory of Open Access Journals (Sweden)
CH Vishnu Vardhan Reddy
2016-10-01
Full Text Available In the open access restructured power system market, it is necessary to develop an appropriate pricing scheme that can provide the useful economic information to market participants, such as generation, transmission companies and customers. Though many methods have already been proposed, but accurately estimating and allocating the transmission cost in the transmission pricing scheme is still a challenging task. This work addresses the problem of allocating the cost of the transmission network to generators and demands. In this work four methods using DC Power flow and AC power flow have been attempted. They are MW-Mile Method, MVA-Mile Method, GGDF method and Bialek Tracing method.MVA-Mile method and Bialek Tracing method applies AC power flow and considers apparent power flows. The purpose of the present work is to allocate the cost pertaining to the transmission lines of the network to all the generators and demands. A load flow solution is run and, the proposed method determines how line flows depend on nodal currents. This result is then used to allocate network costs to generators and demands. The technique presented in this work is related to the allocation of the cost to GENCO‘s TRANSCO‘s and DISCO‘s. A technique for tracing the flow of electricity of lines among generators with GGDF and Bialek upstream looking algorithm is proposed. With these methods correct economic signals are generated for all players. All these methods are tested on IEEE 14 bus system
Flow Field Analysis of Submerged Horizontal Plate Type Breakwater
Institute of Scientific and Technical Information of China (English)
张志强; 栾茂田; 王科
2013-01-01
Submerged horizontal plate can be considered as a new concept breakwater. In order to reveal the wave elimination mechanism of this type breakwater, boundary element method is utilized to investigate the velocity field around plate carefully. The flow field analysis shows that the interaction between incident wave and reverse flow caused by submerged plate will lead to the formation of wave elimination area around both sides of the plate. The velocity magnitude of flow field has been reduced and this is the main reason of wave elimination.
Flow "Fine" Synthesis: High Yielding and Selective Organic Synthesis by Flow Methods.
Kobayashi, Shū
2016-02-18
The concept of flow "fine" synthesis, that is, high yielding and selective organic synthesis by flow methods, is described. Some examples of flow "fine" synthesis of natural products and APIs are discussed. Flow methods have several advantages over batch methods in terms of environmental compatibility, efficiency, and safety. However, synthesis by flow methods is more difficult than synthesis by batch methods. Indeed, it has been considered that synthesis by flow methods can be applicable for the production of simple gasses but that it is difficult to apply to the synthesis of complex molecules such as natural products and APIs. Therefore, organic synthesis of such complex molecules has been conducted by batch methods. On the other hand, syntheses and reactions that attain high yields and high selectivities by flow methods are increasingly reported. Flow methods are leading candidates for the next generation of manufacturing methods that can mitigate environmental concerns toward sustainable society. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.
Methods for measurement of cerebral blood flow in man
DEFF Research Database (Denmark)
Lassen, N A
1976-01-01
A survey of the currently available methods for the measurement of cerebral blood flow in man is given. Many of the clinically important brain diseases such as tumors, stroke, brain trauma or epilepsy entail focal or regional flow alterations. Therefore a special emphasis is placed on methods all...
Free-Surface Viscous Flow Solution Methods for Ship Hydrodynamics
Wackers, J.; Koren, B.; Raven, H.C.; Ploeg, A. van der; Starke, A.R.; Deng, G.B.; Queutey, P.; Visonneau, M.; Hino, T.; Ohashi, K.
2011-01-01
The simulation of viscous free-surface water flow is a subject that has reached a certain maturity and is nowadays used in industrial applications, like the simulation of the flow around ships. While almost all methods used are based on the Navier-Stokes equations, the discretisation methods for the
A fictitious domain method for particulate flows with heat transfer
Yu, Z.; Yu, Zhaosheng; Shao, Xueming; Wachs, Anthony
2006-01-01
The distributed-Lagrange-multiplier/fictitious-domain (DLM/FD) method of Glowinski et al. [R. Glowinski, T.-W. Pan, T.I. Hesla, D.D. Joseph, A distributed Lagrange multiplier/fictitious domain method for particulate flows, Int. J. Multiphase Flow 25 (1999) 755–794] is extended to deal with heat
A fictitious domain method for particulate flows with heat transfer
Yu, Zhaosheng; Shao, Xueming; Wachs, Anthony
2006-01-01
The distributed-Lagrange-multiplier/fictitious-domain (DLM/FD) method of Glowinski et al. [R. Glowinski, T.-W. Pan, T.I. Hesla, D.D. Joseph, A distributed Lagrange multiplier/fictitious domain method for particulate flows, Int. J. Multiphase Flow 25 (1999) 755–794] is extended to deal with heat tran
Base flow separation: A comparison of analytical and mass balance methods
Lott, Darline A.; Stewart, Mark T.
2016-04-01
Base flow is the ground water contribution to stream flow. Many activities, such as water resource management, calibrating hydrological and climate models, and studies of basin hydrology, require good estimates of base flow. The base flow component of stream flow is usually determined by separating a stream hydrograph into two components, base flow and runoff. Analytical methods, mathematical functions or algorithms used to calculate base flow directly from discharge, are the most widely used base flow separation methods and are often used without calibration to basin or gage-specific parameters other than basin area. In this study, six analytical methods are compared to a mass balance method, the conductivity mass-balance (CMB) method. The base flow index (BFI) values for 35 stream gages are obtained from each of the seven methods with each gage having at least two consecutive years of specific conductance data and 30 years of continuous discharge data. BFI is cumulative base flow divided by cumulative total discharge over the period of record of analysis. The BFI value is dimensionless, and always varies from 0 to 1. Areas of basins used in this study range from 27 km2 to 68,117 km2. BFI was first determined for the uncalibrated analytical methods. The parameters of each analytical method were then calibrated to produce BFI values as close to the CMB derived BFI values as possible. One of the methods, the power function (aQb + cQ) method, is inherently calibrated and was not recalibrated. The uncalibrated analytical methods have an average correlation coefficient of 0.43 when compared to CMB-derived values, and an average correlation coefficient of 0.93 when calibrated with the CMB method. Once calibrated, the analytical methods can closely reproduce the base flow values of a mass balance method. Therefore, it is recommended that analytical methods be calibrated against tracer or mass balance methods.
CLUSTERING ANALYSIS OF DEBRIS-FLOW STREAMS
Institute of Scientific and Technical Information of China (English)
Yuan-Fan TSAI; Huai-Kuang TSAI; Cheng-Yan KAO
2004-01-01
The Chi-Chi earthquake in 1999 caused disastrous landslides, which triggered numerous debris flows and killed hundreds of people. A critical rainfall intensity line for each debris-flow stream is studied to prevent such a disaster. However, setting rainfall lines from incomplete data is difficult, so this study considered eight critical factors to group streams, such that streams within a cluster have similar rainfall lines. A genetic algorithm is applied to group 377 debris-flow streams selected from the center of an area affected by the Chi-Chi earthquake. These streams are grouped into seven clusters with different characteristics. The results reveal that the proposed method effectively groups debris-flow streams.
Integral methods for shallow free-surface flows with separation
DEFF Research Database (Denmark)
Watanabe, S.; Putkaradze, V.; Bohr, Tomas
2003-01-01
eddy and separated flow. Assuming a variable radial velocity profile as in Karman-Pohlhausen's method, we obtain a system of two ordinary differential equations for stationary states that can smoothly go through the jump. Solutions of the system are in good agreement with experiments. For the flow down......, and stationary jumps, obtained, for instance, behind a sluice gate. We then include time dependence in the model to study the stability of these waves. This allows us to distinguish between sub- and supercritical flows by calculating dispersion relations for wavelengths of the order of the width of the layer.......We study laminar thin film flows with large distortions of the free surface, using the method of averaging across the flow. Two specific problems are studied: the circular hydraulic jump and the flow down an inclined plane. For the circular hydraulic jump our method is able to handle an internal...
Free-Surface Viscous Flow Solution Methods for Ship Hydrodynamics
WACKERS, Jeroen; Koren, Barry; Raven, H.C.; Van Der Ploeg,, Atze; Starke, A.R.; Deng, G.B.; Queutey, P.; VISONNEAU, Michel; Hino, T.; Ohashi, K
2011-01-01
The simulation of viscous free-surface water flow is a subject that has reached a certain maturity and is nowadays used in industrial applications, like the simulation of the flow around ships. While almost all methods used are based on the Navier-Stokes equations, the discretisation methods for the water surface differ widely. Many of these highly different methods are being used with success. We review three of these methods, by describing in detail their implementation in one particular co...
Through flow analysis within axial flow turbomachinery blade rows
Girigoswami, H.
1986-09-01
Using Katsanis' Through Flow Code, inviscid flow through an axial flow compressor rotor blade as well as flow through inlet guide vanes are analyzed and the computed parameters such as meridional velocity distribution, axial velocity distribution along radial lines, and velocity distribution over blade surfaces are presented.
LFSTAT - An R-Package for Low-Flow Analysis
Koffler, D.; Laaha, G.
2012-04-01
When analysing daily streamflow data focusing on low flow and drought, the state of the art is well documented in the Manual on Low-Flow Estimation and Prediction [1] published by the WMO. While it is clear what has to be done, it is not so clear how to preform the analysis and make the calculation as reproducible as possible. Our software solution expands the high preforming statistical open source software package R to analyse daily stream flow data focusing on low-flows. As command-line based programs are not everyone's preference, we also offer a plug-in for the R-Commander, an easy to use graphical user interface (GUI) to analyse data in R. Functionality includes estimation of the most important low-flow indices. Beside standardly used flow indices also BFI and Recession constants can be computed. The main applications of L-moment based Extreme value analysis and regional frequency analysis (RFA) are available. Calculation of streamflow deficits is another important feature. The most common graphics are prepared and can easily be modified according to the users preferences. Graphics include hydrographs for different periods, flexible streamflow deficit plots, baseflow visualisation, flow duration curves as well as double mass curves just to name a few. The package uses a S3-class called lfobj (low-flow objects). Once this objects are created, analysis can be preformed by mouse-click, and a script can be saved to make the analysis easy reproducible. At the moment we are offering implementation of all major methods proposed in the WMO manual on Low-flow Estimation and Predictions. Future plans include e.g. report export in odt-file using odf-weave. We hope to offer a tool to ease and structure the analysis of stream flow data focusing on low-flows and to make analysis transparent and communicable. The package is designed for hydrological research and water management practice, but can also be used in teaching students the first steps in low-flow hydrology.
Ultrasonic 3-D vector flow method for quantitative in vivo peak velocity and flow rate estimation
DEFF Research Database (Denmark)
Holbek, Simon; Ewertsen, Caroline; Bouzari, Hamed;
2017-01-01
Current clinical ultrasound systems are limited to show blood flow movement in either 1-D or 2-D. In this paper, a method for estimating 3-D vector velocities in a plane using the Transverse Oscillation (TO) method, a 32 x 32 element matrix array, and the experimental ultrasound scanner SARUS...... is presented. The aim of this paper is to estimate precise flow rates and peak velocities derived from 3-D vector flow estimates. The emission sequence provides 3-D vector flow estimates at up to 1.145 frames per second in a plane, and was used to estimate 3-D vector flow in a cross sectional image plane....... The method is validated in two phantom studies, where flow rates are measured in a flow-rig, providing a constant parabolic flow, and in a straight-vessel phantom (ø = 8 mm) connected to a flow pump capable of generating time varying waveforms. Flow rates are estimated to be 82.1 ± 2.8 L/min in the flow...
Lattice-Boltzmann Method for Geophysical Plastic Flows
Leonardi, Alessandro; Mendoza, Miller; Herrmann, Hans J
2015-01-01
We explore possible applications of the Lattice-Boltzmann Method for the simulation of geophysical flows. This fluid solver, while successful in other fields, is still rarely used for geotechnical applications. We show how the standard method can be modified to represent free-surface realization of mudflows, debris flows, and in general any plastic flow, through the implementation of a Bingham constitutive model. The chapter is completed by an example of a full-scale simulation of a plastic fluid flowing down an inclined channel and depositing on a flat surface. An application is given, where the fluid interacts with a vertical obstacle in the channel.
Modeling of Unsteady Flow through the Canals by Semiexact Method
Directory of Open Access Journals (Sweden)
Farshad Ehsani
2014-01-01
Full Text Available The study of free-surface and pressurized water flows in channels has many interesting application, one of the most important being the modeling of the phenomena in the area of natural water systems (rivers, estuaries as well as in that of man-made systems (canals, pipes. For the development of major river engineering projects, such as flood prevention and flood control, there is an essential need to have an instrument that be able to model and predict the consequences of any possible phenomenon on the environment and in particular the new hydraulic characteristics of the system. The basic equations expressing hydraulic principles were formulated in the 19th century by Barre de Saint Venant and Valentin Joseph Boussinesq. The original hydraulic model of the Saint Venant equations is written in the form of a system of two partial differential equations and it is derived under the assumption that the flow is one-dimensional, the cross-sectional velocity is uniform, the streamline curvature is small and the pressure distribution is hydrostatic. The St. Venant equations must be solved with continuity equation at the same time. Until now no analytical solution for Saint Venant equations is presented. In this paper the Saint Venant equations and continuity equation are solved with homotopy perturbation method (HPM and comparison by explicit forward finite difference method (FDM. For decreasing the present error between HPM and FDM, the st.venant equations and continuity equation are solved by HAM. The homotopy analysis method (HAM contains the auxiliary parameter ħ that allows us to adjust and control the convergence region of solution series. The study has highlighted the efficiency and capability of HAM in solving Saint Venant equations and modeling of unsteady flow through the rectangular canal that is the goal of this paper and other kinds of canals.
Chromosome analysis and sorting using flow cytometry.
Doležel, Jaroslav; Kubaláková, Marie; Cíhalíková, Jarmila; Suchánková, Pavla; Simková, Hana
2011-01-01
Chromosome analysis and sorting using flow cytometry (flow cytogenetics) is an attractive tool for fractionating plant genomes to small parts. The reduction of complexity greatly simplifies genetics and genomics in plant species with large genomes. However, as flow cytometry requires liquid suspensions of particles, the lack of suitable protocols for preparation of solutions of intact chromosomes delayed the application of flow cytogenetics in plants. This chapter outlines a high-yielding procedure for preparation of solutions of intact mitotic chromosomes from root tips of young seedlings and for their analysis using flow cytometry and sorting. Root tips accumulated at metaphase are mildly fixed with formaldehyde, and solutions of intact chromosomes are prepared by mechanical homogenization. The advantages of the present approach include the use of seedlings, which are easy to handle, and the karyological stability of root meristems, which can be induced to high degree of metaphase synchrony. Chromosomes isolated according to this protocol have well-preserved morphology, withstand shearing forces during sorting, and their DNA is intact and suitable for a range of applications.
Immobilized enzymes in flow-injection analysis: present and trends.
Ruz, J; Lázaro, F; de Castro, M D
1988-01-01
An overview of the use of immobilized enzymes in flow-injection analysis (FIA) is presented. The joint use of FIA and immobilized enzymes means that analytical procedures are easily automated, analytical costs are reduced and methods are faster. The future possibilities for this combination are discussed.
Polynomial interpolation methods for viscous flow calculations
Rubin, S. G.; Khosla, P. K.
1977-01-01
Higher-order collocation procedures which result in block-tridiagonal matrix systems are derived from (1) Taylor series expansions and from (2) polynomial interpolation, and the relationships between the two formulations, called respectively Hermite and spline collocation, are investigated. A Hermite block-tridiagonal system for a nonuniform mesh is derived, and the Hermite approach is extended in order to develop a variable-mesh sixth-order block-tridiagonal procedure. It is shown that all results obtained by Hermite development can be recovered by appropriate spline polynomial interpolation. The additional boundary conditions required for these higher-order procedures are also given. Comparative solutions using second-order accurate finite difference and spline and Hermite formulations are presented for the boundary layer on a flat plate, boundary layers with uniform and variable mass transfer, and the viscous incompressible Navier-Stokes equations describing flow in a driven cavity.
Polynomial interpolation methods for viscous flow calculations
Rubin, S. G.; Khosla, P. K.
1977-01-01
Higher-order collocation procedures which result in block-tridiagonal matrix systems are derived from (1) Taylor series expansions and from (2) polynomial interpolation, and the relationships between the two formulations, called respectively Hermite and spline collocation, are investigated. A Hermite block-tridiagonal system for a nonuniform mesh is derived, and the Hermite approach is extended in order to develop a variable-mesh sixth-order block-tridiagonal procedure. It is shown that all results obtained by Hermite development can be recovered by appropriate spline polynomial interpolation. The additional boundary conditions required for these higher-order procedures are also given. Comparative solutions using second-order accurate finite difference and spline and Hermite formulations are presented for the boundary layer on a flat plate, boundary layers with uniform and variable mass transfer, and the viscous incompressible Navier-Stokes equations describing flow in a driven cavity.
Migration Flows: Measurement, Analysis and Modeling
Willekens, F.J.; White, Michael J.
2016-01-01
This chapter is an introduction to the study of migration flows. It starts with a review of major definition and measurement issues. Comparative studies of migration are particularly difficult because different countries define migration differently and measurement methods are not harmonized. Insigh
Migration Flows: Measurement, Analysis and Modeling
Willekens, F.J.; White, Michael J.
2016-01-01
This chapter is an introduction to the study of migration flows. It starts with a review of major definition and measurement issues. Comparative studies of migration are particularly difficult because different countries define migration differently and measurement methods are not harmonized.
Migration Flows: Measurement, Analysis and Modeling
Willekens, F.J.; White, Michael J.
2016-01-01
This chapter is an introduction to the study of migration flows. It starts with a review of major definition and measurement issues. Comparative studies of migration are particularly difficult because different countries define migration differently and measurement methods are not harmonized. Insigh
Finite difference methods for coupled flow interaction transport models
Directory of Open Access Journals (Sweden)
Shelly McGee
2009-04-01
Full Text Available Understanding chemical transport in blood flow involves coupling the chemical transport process with flow equations describing the blood and plasma in the membrane wall. In this work, we consider a coupled two-dimensional model with transient Navier-Stokes equation to model the blood flow in the vessel and Darcy's flow to model the plasma flow through the vessel wall. The advection-diffusion equation is coupled with the velocities from the flows in the vessel and wall, respectively to model the transport of the chemical. The coupled chemical transport equations are discretized by the finite difference method and the resulting system is solved using the additive Schwarz method. Development of the model and related analytical and numerical results are presented in this work.
COMPUTATIONAL FLOW RATE FEEDBACK AND CONTROL METHOD IN HYDRAULIC ELEVATORS
Institute of Scientific and Technical Information of China (English)
Xu Bing; Ma Jien; Lin Jianjie
2005-01-01
The computational flow rate feedback and control method, which can be used in proportional valve controlled hydraulic elevators, is discussed and analyzed. In a hydraulic elevator with this method, microprocessor receives pressure information from the pressure transducers and computes the flow rate through the proportional valve based on pressure-flow conversion real time algorithm. This hydraulic elevator is of lower cost and energy consumption than the conventional closed loop control hydraulic elevator whose flow rate is measured by a flow meter. Experiments are carried out on a test rig which could simulate the load of hydraulic elevator. According to the experiment results, the means to modify the pressure-flow conversion algorithm are pointed out.
Simulation and analysis of resin flow in injection machine screw
Institute of Scientific and Technical Information of China (English)
Ling-feng LI; Samir MEKID
2008-01-01
A method with simulation and analysis of the resin flow in a screw is presented to ease the control of some problems that may affect the efficiency and the quality of the product among existing screws in an injection machine. The physical model of a screw is established to represent the stress, the strain, the relationship between velocity and stress, and the temperature of the cells. In this paper, a working case is considered where the velocity and the temperature distributions at any section of the flow are obtained. The analysis of the computational results shows an ability to master various parameters depending on the specifications.
NONLINEAR PERTURBATION METHOD FOR CALCULATING AXISYMMETRIC CAVITATIONAL FLOWS
Directory of Open Access Journals (Sweden)
Vasyl Buivol
2013-12-01
Full Text Available A mathematical model of a cavity under the influence of perturbations of various origins is evaluated. The model is based on hydrodynamics of flows with free boundaries and the theory of small perturbations. Specific analysis is provided for cavitational flows behind cones
Ito, Kaori; Yamamoto, Takayuki; Oyama, Yuriko; Tsuruma, Rieko; Saito, Eriko; Saito, Yoshikazu; Ozu, Takeshi; Honjoh, Tsutomu; Adachi, Reiko; Sakai, Shinobu; Akiyama, Hiroshi; Shoji, Masahiro
2016-09-01
Enzyme-linked immunosorbent assay (ELISA) is commonly used to determine food allergens in food products. However, a significant number of ELISAs give an erroneous result, especially when applied to highly processed food. Accordingly, an improved ELISA, which utilizes an extraction solution comprising the surfactant sodium lauryl sulfate (SDS) and reductant 2-mercaptoethanol (2-ME), has been specially developed to analyze food allergens in highly processed food by enhancing analyte protein extraction. Recently, however, the use of 2-ME has become undesirable. In the present study, a new extraction solution containing a human- and eco-friendly reductant, which is convenient to use at the food manufacturing site, has been established. Among three chemicals with different reducing properties, sodium sulfite, tris(3-hydroxypropyl)phosphine, and mercaptoethylamine sodium sulfite was selected as a 2-ME substitute. The protein extraction ability of SDS/0.1 M sodium sulfite solution was comparable to that of SDS/2-ME solution. Next, the ELISA performance for egg, milk, wheat, peanut, and buckwheat was evaluated by using model-processed foods and commercially available food products. The data showed that the SDS/0.1 M sulfite ELISA significantly correlated with the SDS/2-ME ELISA for all food allergens examined (p food allergens in processed food, showing consistency with the SDS/0.1 M sulfite ELISA results. Accordingly, a harmonized analysis system for processed food comprising a screening LF test and a quantitative ELISA with identical extraction solution has been established. The ELISA based on the SDS/0.1 M sulfite extraction solution has now been authorized as the revised official method for food allergen analysis in Japan.
Methods for studying biofilm formation: flow cells and confocal laser scanning microscopy
DEFF Research Database (Denmark)
Tolker-Nielsen, Tim; Sternberg, Claus
2014-01-01
In this chapter methods for growing and analyzing biofilms under hydrodynamic conditions in flow cells are described. Use of flow cells allows for direct microscopic investigation of biofilm formation. The flow in these chambers is essentially laminar, which means that the biofilms can be grown u......, inoculation of the flow cells, running of the system, confocal laser scanning microscopy and image analysis, and disassembly and cleaning of the system.......In this chapter methods for growing and analyzing biofilms under hydrodynamic conditions in flow cells are described. Use of flow cells allows for direct microscopic investigation of biofilm formation. The flow in these chambers is essentially laminar, which means that the biofilms can be grown...
Topology Method for Analyses of 3—D Viscous Flow Structure in Transonic Turbomachinery
Institute of Scientific and Technical Information of China (English)
YanhuGuo; BaoguoWang; 等
1997-01-01
A topology method is presented in this paper to reveal flow tructure occurring insie turbomachinery,in which near wall flow structure is revealed by using wall limiting streamilines and space flow feature is revealed by using space streamilines and cross-section streamlines,As an example ,a computational three-dimensional viscous flow field inside a transonic turbine cascade is studied.Through the analysis,the form and evolution of vortex system and the whole process of separation occurring within this cascade are revealed.The application of topology method for analyze flow structure inside turbomachinmery is very important for understanding flow features and mechanism of flow loss even for improving the design of turbomachinery and increasing its efficiency.
FINITE DIFFERENCE METHOD FOR CALCULATING OF THE GAS FLOW IN A SUBSONIC GAS EJECTOR
Directory of Open Access Journals (Sweden)
Kostjantin Kapitanchuk
2015-12-01
Full Text Available Describe analysis of eddy viscosity actual mathematical models for numerical simulation a reversal gas flow in subsonic gas ejector. Considered advantages and disadvantages each of it. Proposed use method of finite elements for provides viscous gas flow calculation of gas ejectors.
Maximum entropy analysis of flow and reaction networks
Niven, Robert K.; Abel, Markus; Schlegel, Michael; Waldrip, Steven H.
2015-01-01
We present a generalised MaxEnt method to infer the stationary state of a flow network, subject to "observable" constraints on expectations of various parameters, as well as "physical" constraints arising from frictional properties (resistance functions) and conservation laws (Kirchhoff laws). The method invokes an entropy defined over all uncertainties in the system, in this case the internal and external flow rates and potential differences. The proposed MaxEnt framework is readily extendable to the analysis of networks with uncertainty in the network structure itself.
Methods for early prediction of lactation flow in Holstein heifers
Directory of Open Access Journals (Sweden)
Vesna Gantner
2010-12-01
Full Text Available The aim of this research was to define methods for early prediction (based on I. milk control record of lactation flow in Holstein heifers as well as to choose optimal one in terms of prediction fit and application simplicity. Total of 304,569 daily yield records automatically recorded on a 1,136 first lactation Holstein cows, from March 2003 till August 2008., were included in analysis. According to the test date, calving date, the age at first calving, lactation stage when I. milk control occurred and to the average milk yield in first 25th, T1 (and 25th-45th, T2 lactation days, measuring monthcalving month-age-production-time-period subgroups were formed. The parameters of analysed nonlinear and linear methods were estimated for each defined subgroup. As models evaluation measures,adjusted coefficient of determination, and average and standard deviation of error were used. Considering obtained results, in terms of total variance explanation (R2 adj, the nonlinear Wood’s method showed superiority above the linear ones (Wilmink’s, Ali-Schaeffer’s and Guo-Swalve’s method in both time-period subgroups (T1 - 97.5 % of explained variability; T2 - 98.1 % of explained variability. Regarding the evaluation measures based on prediction error amount (eavg±eSD, the lowest average error of daily milk yield prediction (less than 0.005 kg/day, as well as of lactation milk yield prediction (less than 50 kg/lactation (T1 time-period subgroup and less than 30 kg/lactation (T2 time-period subgroup; were determined when Wood’s nonlinear prediction method were applied. Obtained results indicate that estimated Wood’s regression parameters could be used in routine work for early prediction of Holstein heifer’s lactation flow.
Numerical method for a moving solid object in flows.
Yokoi, Kensuke
2003-04-01
We propose a numerical method for dealing with a moving solid body that interacts with a complex liquid surface. The method is based on the level set method, the CIP method, and the ghost fluid method. The validity of the method was shown by applying it to Poiseuille and Couette flow problems. The method can precisely capture the boundary layer as well as a moving solid object.
Load flow analysis using decoupled fuzzy load flow under critical ...
African Journals Online (AJOL)
user
of power system, reliable fuzzy load flow is developed to overcome the limitations of the ... of power mismatches are taken as two inputs for fuzzy logic controller. ..... Programming Based Load Flow Algorithm For Systems Containing Unified ...
Chang, J. L. C.; Kwak, D.; Rogers, S. E.; Yang, R.-J.
1988-01-01
This paper discusses incompressible Navier-Stokes solution methods with an emphasis on the pseudocompressibility method. A steady-state flow solver based on the pseudocompressibility approach is then described. This flow solver code has been used to analyze the internal flow in the Space Shuttle main engine hot-gas manifold. Salient features associated with this three-dimensional realistic flow simulation are discussed. Numerical solutions relevant to the current engine analysis and the redesign effort are discussed along with experimental results. This example demonstrates the potential of computational fluid dynamics as a design tool for aerospace applications.
Through flow analysis of pumps and fans
Neal, A. N.
1980-08-01
Incompressible through flow calculations in axial, mixed and centrifugal flow pumps and fans are described. An iterative scheme is used. A simple blade to blade model is applied on the surfaces of revolution defined by the meridional streamlines. This defines the fluid properties and the mean stream surface (S2 surface) for the next meridional solution. A computer program is available allowing the method to be applied for design purposes. APL is used for input and output and FORTRAN IV for computation. A typical calculation requires 30 sec of Univac 1100 time.
OpenFlow Deployment and Concept Analysis
Directory of Open Access Journals (Sweden)
Tomas Hegr
2013-01-01
Full Text Available Terms such as SDN and OpenFlow (OF are often used in the research and development of data networks. This paper deals with the analysis of the current state of OpenFlow protocol deployment options as it is the only real representative protocol that enables the implementation of Software Defined Networking outside an academic world. There is introduced an insight into the current state of the OpenFlow specification development at various levels is introduced. The possible limitations associated with this concept in conjunction with the latest version (1.3 of the specification published by ONF are also presented. In the conclusion there presented a demonstrative security application addressing the lack of IPv6 support in real network devices since most of today's switches and controllers support only OF v1.0.
Solving functional flow equations with pseudo-spectral methods
Borchardt, Julia
2016-01-01
We apply pseudo-spectral methods to integrate functional flow equations with high accuracy, extending earlier work on functional fixed point equations \\cite{Borchardt:2015rxa}. The advantages of our method are illustrated with the help of two classes of models: first, to make contact with literature, we investigate flows of the O$(N)$-model in 3 dimensions, for $N=1, 4$ and in the large $N$ limit. For the case of a fractal dimension, $d=2.4$, and $N=1$, we follow the flow along a separatrix from a multicritical fixed point to the Wilson-Fisher fixed point over almost 13 orders of magnitude. As a second example, we consider flows of bounded quantum-mechanical potentials, which can be considered as a toy model for Higgs inflation. Such flows pose substantial numerical difficulties, and represent a perfect test bed to exemplify the power of pseudo-spectral methods.
A Reconstruction Method of Blood Flow Velocity in Left Ventricle Using Color Flow Ultrasound
Directory of Open Access Journals (Sweden)
Jaeseong Jang
2015-01-01
Full Text Available Vortex flow imaging is a relatively new medical imaging method for the dynamic visualization of intracardiac blood flow, a potentially useful index of cardiac dysfunction. A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color flow images compiled from ultrasound measurements. In this paper, a 2D incompressible Navier-Stokes equation with a mass source term is proposed to utilize the measurable color flow ultrasound data in a plane along with the moving boundary condition. The proposed model reflects out-of-plane blood flows on the imaging plane through the mass source term. The boundary conditions to solve the system of equations are derived from the dimensions of the ventricle extracted from 2D echocardiography data. The performance of the proposed method is evaluated numerically using synthetic flow data acquired from simulating left ventricle flows. The numerical simulations show the feasibility and potential usefulness of the proposed method of reconstructing the intracardiac flow fields. Of particular note is the finding that the mass source term in the proposed model improves the reconstruction performance.
Review of Upscaling Methods for Describing Unsaturated Flow
Energy Technology Data Exchange (ETDEWEB)
Wood, Brian D.
2000-09-26
Representing samll-scale features can be a challenge when one wants to model unsaturated flow in large domains. In this report, the various upscaling techniques are reviewed. The following upscaling methods have been identified from the literature: stochastic methods, renormalization methods, volume averaging and homogenization methods. In addition, a final technique, full resolution numerical modeling, is also discussed.
Constrained blind deconvolution using Wirtinger flow methods
Walk, Philipp
2017-09-04
In this work we consider one-dimensional blind deconvolution with prior knowledge of signal autocorrelations in the classical framework of polynomial factorization. In particular this univariate case highly suffers from several non-trivial ambiguities and therefore blind deconvolution is known to be ill-posed in general. However, if additional autocorrelation information is available and the corresponding polynomials are co-prime, blind deconvolution is uniquely solvable up to global phase. Using lifting, the outer product of the unknown vectors is the solution to a (convex) semi-definite program (SDP) demonstrating that -theoretically- recovery is computationally tractable. However, for practical applications efficient algorithms are required which should operate in the original signal space. To this end we also discuss a gradient descent algorithm (Wirtinger flow) for the original non-convex problem. We demonstrate numerically that such an approach has performance comparable to the semidefinite program in the noisy case. Our work is motivated by applications in blind communication scenarios and we will discuss a specific signaling scheme where information is encoded into polynomial roots.
Analysis of groundwater flow beneath ice sheets
Energy Technology Data Exchange (ETDEWEB)
Boulton, G. S.; Zatsepin, S.; Maillot, B. [Univ. of Edinburgh (United Kingdom). Dept. of Geology and Geophysics
2001-03-01
The large-scale pattern of subglacial groundwater flow beneath European ice sheets was analysed in a previous report. It was based on a two-dimensional flowline model. In this report, the analysis is extended to three dimensions by exploring the interactions between groundwater and tunnel flow. A theory is developed which suggests that the large-scale geometry of the hydraulic system beneath an ice sheet is a coupled, self-organising system. In this system the pressure distribution along tunnels is a function of discharge derived from basal meltwater delivered to tunnels by groundwater flow, and the pressure along tunnels itself sets the base pressure which determines the geometry of catchments and flow towards the tunnel. The large-scale geometry of tunnel distribution is a product of the pattern of basal meltwater production and the transmissive properties of the bed. The tunnel discharge from the ice margin of the glacier, its seasonal fluctuation and the sedimentary characteristics of eskers are largely determined by the discharge of surface meltwater which penetrates to the bed in the terminal zone. The theory explains many of the characteristics of esker systems and can account for tunnel valleys. It is concluded that the large-scale hydraulic regime beneath ice sheets is largely a consequence of groundwater/tunnel flow interactions and that it is essential similar to non-glacial hydraulic regimes. Experimental data from an Icelandic glacier, which demonstrates measured relationships between subglacial tunnel flow and groundwater flow during the transition from summer to winter seasons for a modern glacier, and which support the general conclusions of the theory is summarised in an appendix.
On the peculiarities of LDA method in two-phase flows with high concentrations of particles
Poplavski, S. V.; Boiko, V. M.; Nesterov, A. U.
2016-10-01
Popular applications of laser Doppler anemometry (LDA) in gas dynamics are reviewed. It is shown that the most popular method cannot be used in supersonic flows and two-phase flows with high concentrations of particles. A new approach to implementation of the known LDA method based on direct spectral analysis, which offers better prospects for such problems, is presented. It is demonstrated that the method is suitable for gas-liquid jets. Owing to the progress in laser engineering, digital recording of spectra, and computer processing of data, the method is implemented at a higher technical level and provides new prospects of diagnostics of high-velocity dense two-phase flows.
Flow analysis of C. elegans swimming
Montenegro-Johnson, Thomas; Gagnon, David; Arratia, Paulo; Lauga, Eric
2015-11-01
Improved understanding of microscopic swimming has the potential to impact numerous biomedical and industrial processes. A crucial means of analyzing these systems is through experimental observation of flow fields, from which it is important to be able to accurately deduce swimmer physics such as power consumption, drag forces, and efficiency. We examine the swimming of the nematode worm C. elegans, a model system for undulatory micro-propulsion. Using experimental data of swimmer geometry and kinematics, we employ the regularized stokeslet boundary element method to simulate the swimming of this worm outside the regime of slender-body theory. Simulated flow fields are then compared with experimentally extracted values confined to the swimmer beat plane, demonstrating good agreement. We finally address the question of how to estimate three-dimensional flow information from two-dimensional measurements.
Computational Analysis of Human Blood Flow
Panta, Yogendra; Marie, Hazel; Harvey, Mark
2009-11-01
Fluid flow modeling with commercially available computational fluid dynamics (CFD) software is widely used to visualize and predict physical phenomena related to various biological systems. In this presentation, a typical human aorta model was analyzed assuming the blood flow as laminar with complaint cardiac muscle wall boundaries. FLUENT, a commercially available finite volume software, coupled with Solidworks, a modeling software, was employed for the preprocessing, simulation and postprocessing of all the models.The analysis mainly consists of a fluid-dynamics analysis including a calculation of the velocity field and pressure distribution in the blood and a mechanical analysis of the deformation of the tissue and artery in terms of wall shear stress. A number of other models e.g. T branches, angle shaped were previously analyzed and compared their results for consistency for similar boundary conditions. The velocities, pressures and wall shear stress distributions achieved in all models were as expected given the similar boundary conditions. The three dimensional time dependent analysis of blood flow accounting the effect of body forces with a complaint boundary was also performed.
PDF methods for combustion in high-speed turbulent flows
Pope, Stephen B.
1995-01-01
This report describes the research performed during the second year of this three-year project. The ultimate objective of the project is extend the applicability of probability density function (pdf) methods from incompressible to compressible turbulent reactive flows. As described in subsequent sections, progress has been made on: (1) formulation and modelling of pdf equations for compressible turbulence, in both homogeneous and inhomogeneous inert flows; and (2) implementation of the compressible model in various flow configurations, namely decaying isotropic turbulence, homogeneous shear flow and plane mixing layer.
Construction of School Timetables by Flow Methods.
de Werra, D.
In this paper, a heuristic algorithm for constructing school timetables is described. The algorithm is based on an exact method that applies to a family of particular timetable problems. The procedure has been used to construct timetables for Swiss schools having about 50 classes, 80 teachers, and 35 weekly periods. Less than five percent of…
Impedance Flow Cytometry: A Novel Technique in Pollen Analysis
Heidmann, Iris; Schade-Kampmann, Grit; Lambalk, Joep; Ottiger, Marcel; Di Berardino, Marco
2016-01-01
Introduction An efficient and reliable method to estimate plant cell viability, especially of pollen, is important for plant breeding research and plant production processes. Pollen quality is determined by classical methods, like staining techniques or in vitro pollen germination, each having disadvantages with respect to reliability, analysis speed, and species dependency. Analysing single cells based on their dielectric properties by impedance flow cytometry (IFC) has developed into a comm...
A flux monitoring method for easy and accurate flow rate measurement in pressure-driven flows.
Siria, Alessandro; Biance, Anne-Laure; Ybert, Christophe; Bocquet, Lydéric
2012-03-07
We propose a low-cost and versatile method to measure flow rate in microfluidic channels under pressure-driven flows, thereby providing a simple characterization of the hydrodynamic permeability of the system. The technique is inspired by the current monitoring method usually employed to characterize electro-osmotic flows, and makes use of the measurement of the time-dependent electric resistance inside the channel associated with a moving salt front. We have successfully tested the method in a micrometer-size channel, as well as in a complex microfluidic channel with a varying cross-section, demonstrating its ability in detecting internal shape variations.
FINITE VOLUME METHOD OF MODELLING TRANSIENT GROUNDWATER FLOW
Directory of Open Access Journals (Sweden)
N. Muyinda
2014-01-01
Full Text Available In the field of computational fluid dynamics, the finite volume method is dominant over other numerical techniques like the finite difference and finite element methods because the underlying physical quantities are conserved at the discrete level. In the present study, the finite volume method is used to solve an isotropic transient groundwater flow model to obtain hydraulic heads and flow through an aquifer. The objective is to discuss the theory of finite volume method and its applications in groundwater flow modelling. To achieve this, an orthogonal grid with quadrilateral control volumes has been used to simulate the model using mixed boundary conditions from Bwaise III, a Kampala Surburb. Results show that flow occurs from regions of high hydraulic head to regions of low hydraulic head until a steady head value is achieved.
DEMONSTRATION BULLETIN: COLLOID POLISHING FILTER METHOD - FILTER FLOW TECHNOLOGY, INC.
The Filter Flow Technology, Inc. (FFT) Colloid Polishing Filter Method (CPFM) was tested as a transportable, trailer mounted, system that uses sorption and chemical complexing phenomena to remove heavy metals and nontritium radionuclides from water. Contaminated waters can be pro...
Pressure algorithm for elliptic flow calculations with the PDF method
Anand, M. S.; Pope, S. B.; Mongia, H. C.
1991-01-01
An algorithm to determine the mean pressure field for elliptic flow calculations with the probability density function (PDF) method is developed and applied. The PDF method is a most promising approach for the computation of turbulent reacting flows. Previous computations of elliptic flows with the method were in conjunction with conventional finite volume based calculations that provided the mean pressure field. The algorithm developed and described here permits the mean pressure field to be determined within the PDF calculations. The PDF method incorporating the pressure algorithm is applied to the flow past a backward-facing step. The results are in good agreement with data for the reattachment length, mean velocities, and turbulence quantities including triple correlations.
Computational methods for two-phase flow and particle transport
Lee, Wen Ho
2013-01-01
This book describes mathematical formulations and computational methods for solving two-phase flow problems with a computer code that calculates thermal hydraulic problems related to light water and fast breeder reactors. The physical model also handles the particle and gas flow problems that arise from coal gasification and fluidized beds. The second part of this book deals with the computational methods for particle transport.
Tensor product decomposition methods applied to complex flow data
von Larcher, Thomas; Klein, Rupert; Schneider, Reinhold; Wolf, Sebastian; Huber, Benjamin
2017-04-01
Low-rank multilevel approximation methods are an important tool in numerical analysis and in scientific computing. Those methods are often suited to attack high-dimensional problems successfully and allow very compact representations of large data sets. Specifically, hierarchical tensor product decomposition methods emerge as an promising approach for application to data that are concerned with cascade-of-scales problems as, e.g., in turbulent fluid dynamics. We focus on two particular objectives, that is representing turbulent data in an appropriate compact form and, secondly and as a long-term goal, finding self-similar vortex structures in multiscale problems. The question here is whether tensor product methods can support the development of improved understanding of the multiscale behavior and whether they are an improved starting point in the development of compact storage schemes for solutions of such problems relative to linear ansatz spaces. We present the reconstruction capabilities of a tensor decomposition based modeling approach tested against 3D turbulent channel flow data.
Finite volume methods for submarine debris flows and generated waves
Kim, Jihwan; Løvholt, Finn; Issler, Dieter
2016-04-01
Submarine landslides can impose great danger to the underwater structures and generate destructive tsunamis. Submarine debris flows often behave like visco-plastic materials, and the Herschel-Bulkley rheological model is known to be appropriate for describing the motion. In this work, we develop numerical schemes for the visco-plastic debris flows using finite volume methods in Eulerian coordinates with two horizontal dimensions. We provide parameter sensitivity analysis and demonstrate how common ad-hoc assumptions such as including a minimum shear layer depth influence the modeling of the landslide dynamics. Hydrodynamic resistance forces, hydroplaning, and remolding are all crucial terms for underwater landslides, and are hence added into the numerical formulation. The landslide deformation is coupled to the water column and simulated in the Clawpack framework. For the propagation of the tsunamis, the shallow water equations and the Boussinesq-type equations are employed to observe how important the wave dispersion is. Finally, two cases in central Norway, i.e. the subaerial quick clay landslide at Byneset in 2012, and the submerged tsunamigenic Statland landslide in 2014, are both presented for validation. The research leading to these results has received funding from the Research Council of Norway under grant number 231252 (Project TsunamiLand) and the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement 603839 (Project ASTARTE).
Institute of Scientific and Technical Information of China (English)
Zheng Yingren; Deng Chujian; Wang Jinglin
2010-01-01
At present,associated flow rule of traditional plastic theory is adopted in the slip line field theory and upper bound method of geotechnical materials.So the stress characteristic line conforms to the velocity line.It is proved that geotechnical materials do not abide by the associated flow rule.It is impossible for the stress characteristic line to conform to the velocity line.Generalized plastic mechanics theoretically proved that plastic potential surface intersects the Mohr-Coulomb yield surface with an angle,so that the velocity line must be studied by non-associated flow rule.According to limit analysis theory,the theory of slip line field is put forward in this paper,and then the ultimate boating capacity of strip footing is obtained based on the associated flow rule and the non-associated flow rule individually.These two results are identical since the ultimate bearing capacity is independent of flow rule.On the contrary,the velocity fields of associated and non-associated flow rules are different which shows the velocity field based on the associated flow rule is incorrect.
Operational modal analysis of flow-induced vibration of nuclear fuel rods in a turbulent axial flow
Energy Technology Data Exchange (ETDEWEB)
De Pauw, B., E-mail: bdepauw@vub.ac.be [Vrije Universiteit Brussel (VUB), Brussels Photonics Team (B-Phot), Brussels (Belgium); Vrije Universiteit Brussel (VUB), Department of Mechanical Engineering (AVRG), Brussels (Belgium); Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, Mol (Belgium); Weijtjens, W.; Vanlanduit, S. [Vrije Universiteit Brussel (VUB), Department of Mechanical Engineering (AVRG), Brussels (Belgium); Van Tichelen, K. [Belgian Nuclear Research Centre (SCK-CEN), Boeretang 200, Mol (Belgium); Berghmans, F. [Vrije Universiteit Brussel (VUB), Brussels Photonics Team (B-Phot), Brussels (Belgium)
2015-04-01
Highlights: • We describe an analysis technique to evaluate nuclear fuel pins. • We test a single fuel pin mockup subjected to turbulent axial flow. • Our analysis is based on operational modal analysis (OMA). • The accuracy and precision of our method is higher compared to traditional methods. • We demonstrate the possible onset of a fluid-elastic instability. - Abstract: Flow-induced vibration of nuclear reactor fuel pins can result in mechanical noise and lead to failure of the reactor's fuel assembly. This problem can be exacerbated in the new generation of liquid heavy metal fast reactors that use a much denser and more viscous coolant in the reactor core. An investigation of the flow-induced vibration in these particular conditions is therefore essential. In this paper, we describe an analysis technique to evaluate flow-induced vibration of nuclear reactor fuel pins subjected to a turbulent axial flow of heavy metal. We deal with a single fuel pin mockup designed for the lead–bismuth eutectic (LBE) cooled MYRRHA reactor which is subjected to similar flow conditions as in the reactor core. Our analysis is based on operational modal analysis (OMA) techniques. We show that the accuracy and precision of our OMA technique is higher compared to traditional methods and that it allows evaluating the evolution of modal parameters in operational conditions. We also demonstrate the possible onset of a fluid-elastic instability by tracking the modal parameters with increasing flow velocity.
NUMERICAL ANALYSIS OF A FEM FOR A TRANSIENT VISCOELASTIC FLOW
Institute of Scientific and Technical Information of China (English)
穆君; 冯民富
2004-01-01
We present the numerical analysis of a coupled method for the numerical simulation of transient viscoelastic flow obeying a differential constitutive equation with a Newtonian viscosity. The scheme used is based on Euler implicit method in time and maintains at each time step a couple of the velocity u and the viscoelastic part of the stress σ. Approximation in space is made by finite element method. The approximate stress, velocity and pressure are, respectively, P1-continuous, p2-continuous, and p1continuous. Upwinding needed for convection of σ is made by a "Streamline Upwind Petrov Galerkin" method (SUPG).
Multiscale analysis and computation for flows in heterogeneous media
Energy Technology Data Exchange (ETDEWEB)
Efendiev, Yalchin [Texas A & M Univ., College Station, TX (United States); Hou, T. Y. [California Inst. of Technology (CalTech), Pasadena, CA (United States); Durlofsky, L. J. [Stanford Univ., CA (United States); Tchelepi, H. [Stanford Univ., CA (United States)
2016-08-04
Our work in this project is aimed at making fundamental advances in multiscale methods for flow and transport in highly heterogeneous porous media. The main thrust of this research is to develop a systematic multiscale analysis and efficient coarse-scale models that can capture global effects and extend existing multiscale approaches to problems with additional physics and uncertainties. A key emphasis is on problems without an apparent scale separation. Multiscale solution methods are currently under active investigation for the simulation of subsurface flow in heterogeneous formations. These procedures capture the effects of fine-scale permeability variations through the calculation of specialized coarse-scale basis functions. Most of the multiscale techniques presented to date employ localization approximations in the calculation of these basis functions. For some highly correlated (e.g., channelized) formations, however, global effects are important and these may need to be incorporated into the multiscale basis functions. Other challenging issues facing multiscale simulations are the extension of existing multiscale techniques to problems with additional physics, such as compressibility, capillary effects, etc. In our project, we explore the improvement of multiscale methods through the incorporation of additional (single-phase flow) information and the development of a general multiscale framework for flows in the presence of uncertainties, compressible flow and heterogeneous transport, and geomechanics. We have considered (1) adaptive local-global multiscale methods, (2) multiscale methods for the transport equation, (3) operator-based multiscale methods and solvers, (4) multiscale methods in the presence of uncertainties and applications, (5) multiscale finite element methods for high contrast porous media and their generalizations, and (6) multiscale methods for geomechanics. Below, we present a brief overview of each of these contributions.
Integrated numerical methods for hypersonic aircraft cooling systems analysis
Petley, Dennis H.; Jones, Stuart C.; Dziedzic, William M.
1992-01-01
Numerical methods have been developed for the analysis of hypersonic aircraft cooling systems. A general purpose finite difference thermal analysis code is used to determine areas which must be cooled. Complex cooling networks of series and parallel flow can be analyzed using a finite difference computer program. Both internal fluid flow and heat transfer are analyzed, because increased heat flow causes a decrease in the flow of the coolant. The steady state solution is a successive point iterative method. The transient analysis uses implicit forward-backward differencing. Several examples of the use of the program in studies of hypersonic aircraft and rockets are provided.
This method provides a procedure for determining nitrate and nitrite concentrations in estuarine and coastal waters. Nitrate is reduced to nitrite by cadmium,1-3 and the resulting nitrite determined by formation of an azo dye.4-6
[Substance flow analysis on phosphorus cycle in Dianchi basin, China].
Liu, Yi; Chen, Ji-Ning
2006-08-01
Investigation of physical profiles of nutrients within socio-economic systems is one of the key approaches to cure eutrophication. Applying a substance flow analysis (SFA) method for the case of Dianchi basin located in southwest of China, we established a regional static SFA model (PHOSFAD) in 2000 via balancing societal phosphorus flows. Aggregate characteristics of the overall phosphorus throughput, and physical efficiencies in relation to phosphorus uses of production and consumption sectors, including mining, processing, farming, livestock husbandry and household consumption, were subsequently identified. The methodology and results of this study illustrate applicability and value for rational decision-making aiming to curb eutrophication of Dianchi Lake.
Vortex dominated flows. Analysis and computation for multiple scale phenomena
Energy Technology Data Exchange (ETDEWEB)
Ting, L. [New York Univ., NY (United States). Courant Inst. of Mathematical Sciences; Klein, R. [Freie Univ. Berlin (Germany). Fachbereich Mathematik und Informatik; Knio, O.M. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Mechanical Engineering
2007-07-01
This monograph provides in-depth analyses of vortex dominated flows via matched and multiscale asymptotics, and demonstrates how insight gained through these analyses can be exploited in the construction of robust, efficient, and accurate numerical techniques. The book explores the dynamics of slender vortex filaments in detail, including fundamental derivations, compressible core structure, weakly non-linear limit regimes, and associated numerical methods. Similarly, the volume covers asymptotic analysis and computational techniques for weakly compressible flows involving vortex-generated sound and thermoacoustics. The book is addressed to both graduate students and researchers. (orig.)
Active Flow Control and Global Stability Analysis of Separated Flow Over a NACA 0012 Airfoil
Munday, Phillip M.
definition of the coefficient of momentum, which successfully characterizes suppression of separation and lift enhancement. The effect of angular momentum is incorporated into the modified coefficient of momentum by introducing a characteristic swirling jet velocity based on the non-dimensional swirl number. With the modified coefficient of momentum, this single value is able to categorize controlled flows into separated, transitional, and attached flows. With inadequate control input (separated flow regime), lift decreased compared to the baseline flow. Increasing the modified coefficient of momentum, flow transitions from separated to attached and accordingly results in improved aerodynamic forces. Modifying the spanwise spacing, it is shown that the minimum modified coefficient of momentum input required to begin transitioning the flow is dependent on actuator spacing. The growth (or decay) of perturbations can facilitate or inhibit the influence of flow control inputs. Biglobal stability analysis is considered to further analyze the behavior of control inputs on separated flow over a symmetric airfoil. Assuming a spanwise periodic waveform for the perturbations, the eigenvalues and eigenvectors about a base flow are solved to understand the influence of spanwise variation on the development of the flow. Two algorithms are developed and validated to solve for the eigenvalues of the flow: an algebraic eigenvalue solver (matrix based) and a time-stepping algorithm. The matrix based approach is formulated without ever storing the matrices, creating a computationally memory efficient algorithm. Increasing the Reynolds number to Re = 23,000 over a NACA 0012 airfoil, the time-stepper method is implemented due to rising computational cost of the matrix-based method. Stability analysis about the time-averaged flow is performed for spanwise wavenumbers of beta = 1/c, 10pi/ c and 20pi/c, which the latter two wavenumbers are representative of the spanwise spacing between the
A study of methods to estimate debris flow velocity
Prochaska, A.B.; Santi, P.M.; Higgins, J.D.; Cannon, S.H.
2008-01-01
Debris flow velocities are commonly back-calculated from superelevation events which require subjective estimates of radii of curvature of bends in the debris flow channel or predicted using flow equations that require the selection of appropriate rheological models and material property inputs. This research investigated difficulties associated with the use of these conventional velocity estimation methods. Radii of curvature estimates were found to vary with the extent of the channel investigated and with the scale of the media used, and back-calculated velocities varied among different investigated locations along a channel. Distinct populations of Bingham properties were found to exist between those measured by laboratory tests and those back-calculated from field data; thus, laboratory-obtained values would not be representative of field-scale debris flow behavior. To avoid these difficulties with conventional methods, a new preliminary velocity estimation method is presented that statistically relates flow velocity to the channel slope and the flow depth. This method presents ranges of reasonable velocity predictions based on 30 previously measured velocities. ?? 2008 Springer-Verlag.
[Application of three heat pulse technique-based methods to determine the stem sap flow].
Wang, Sheng; Fan, Jun
2015-08-01
It is of critical importance to acquire tree transpiration characters through sap flow methodology to understand tree water physiology, forest ecology and ecosystem water exchange. Tri-probe heat pulse sensors, which are widely utilized in soil thermal parameters and soil evaporation measurement, were applied to implement Salix matsudana sap flow density (Vs) measurements via heat-ratio method (HRM), T-Max method (T-Max) and single-probe heat pulse probe (SHPP) method, and comparative analysis was conducted with additional Grainer's thermal diffusion probes (TDP) measured results. The results showed that, it took about five weeks to reach a stable measurement stage after TPHP installation, Vs measured with three methods in the early stage after installation was 135%-220% higher than Vs in the stable measurement stage, and Vs estimated via HRM, T-Max and SHPP methods were significantly linearly correlated with Vs estimated via TDP method, with R2 of 0.93, 0.73 and 0.91, respectively, and R2 for Vs measured by SHPP and HRM reached 0.94. HRM had relatively higher precision in measuring low rates and reverse sap flow. SHPP method seemed to be very promising to measure sap flow for configuration simplicity and high measuring accuracy, whereas it couldn' t distinguish directions of flow. T-Max method had relatively higher error in sap flow measurement, and it couldn' t measure sap flow below 5 cm3 · cm(-2) · h(-1), thus this method could not be used alone, however it could measure thermal diffusivity for calculating sap flow when other methods were imposed. It was recommended to choose a proper method or a combination of several methods to measure stem sap flow, based on specific research purpose.
Nitrogen Flow Analysis in Huizhou, South China
Ma, Xiaobo; Wang, Zhaoyin; Yin, Zegao; Koenig, Albert
2008-03-01
Eutrophication due to uncontrolled discharges of nitrogen and phosphorus has become a serious pollution problem in many Chinese rivers. This article analyzes the nitrogen flow in Huizhou City in the East River watershed in south China. The material accounting method was applied to investigate the nitrogen flows related to human activities, which consist of the natural and anthropogenic systems. In Huizhou City, the nonpoint source pollution was quantified by the export coefficient method and the domestic discharge was estimated as the product of per capita nitrogen contribution and population. This research was conducted based on statistical information and field data from 1998 in the Huizhou City. The results indicated that the major nitrogen flows in this area were river loads, fertilizer and feedstuff imports, atmospheric deposition, animal manure volatilization, and processes related to burning and other emissions. In 1998, about 40% of the nitrogen was retained in the system and could result in potential environmental problems. Nitrogen export was mainly by rivers, which account for about 57% of the total nitrogen exported. Comparisons made between the East River and the Danube and Yangtze Rivers show that the unit area nitrogen export was of the same magnitude and the per capita nitrogen export was comparable.
Celá, Andrea; Mádr, Aleš; Dědová, Tereza; Pelcová, Marta; Ješeta, Michal; Žáková, Jana; Crha, Igor; Glatz, Zdeněk
2016-09-01
Evaluating the physiological state of an organism is of clinical importance. In assisted reproduction, knowledge of the embryo's physiology is crucial for selecting the embryo with the highest developmental capacity to ensure high pregnancy rates. Amino acids (AAs) are involved in many biochemical processes during embryo development, which means that the determination of AA fluctuations in the embryo's surroundings can determine the embryo's physiological state. Since current embryo selection methods are mainly based on visual assessment, which lacks proper accuracy, a novel method for the analysis of AAs in the embryo's surroundings was developed. AAs were analyzed by means of MEKC-LIF after on-capillary derivatization by naphthalene-2,3-dicarboxaldehyde. The reactants were injected under the three zone arrangement and mixed using the transverse diffusion of laminar flow profiles methodology. The resulting derivatives of all the standard AAs were baseline resolved in the BGE comprised of 35 mM sodium tetraborate, 55 mM SDS, 2.7 M urea, 1 mM BIS-TRIS propane, and 23 mM NaOH within 50 min. The method was applied on an analysis of spent culture media used in assisted reproduction to culture embryos after in vitro fertilization.
Abdi, Reza; Yasi, Mehdi
2015-01-01
The assessment of environmental flows in rivers is of vital importance for preserving riverine ecosystem processes. This paper addresses the evaluation of environmental flow requirements in three reaches along a typical perennial river (the Zab transboundary river, in north-west Iran), using different hydraulic, hydrological and ecological methods. The main objective of this study came from the construction of three dams and inter-basin transfer of water from the Zab River to the Urmia Lake. Eight hydrological methods (i.e. Tennant, Tessman, flow duration curve analysis, range of variability approach, Smakhtin, flow duration curve shifting, desktop reserve and 7Q2&10 (7-day low flow with a 2- and 10-year return period)); two hydraulic methods (slope value and maximum curvature); and two habitat simulation methods (hydraulic-ecologic, and Q Equation based on water quality indices) were used. Ecological needs of the riverine key species (mainly Barbus capito fish), river geometries, natural flow regime and the environmental status of river management were the main indices for determining the minimum flow requirements. The results indicate that the order of 35%, 17% and 18% of the mean annual flow are to be maintained for the upper, middle and downstream river reaches, respectively. The allocated monthly flow rates in the three Dams steering program are not sufficient to preserve the Zab River life.
METHODS OF MAGNETOTELLURIC ANALYSIS
Magnetotelluric prospecting is a method of geophysical exploration that makes use of the fluctuations in the natural electric and magnetic fields...function of the conductivity structure of the earth’s substrata. This report describes some new methods for analyzing and interpreting magnetotelluric
Clearance gap flow: simulations by discontinuous Galerkin method and experiments
Directory of Open Access Journals (Sweden)
Prausová Helena
2015-01-01
Full Text Available Compressible viscous fluid flow in a narrow gap formed by two parallel plates in distance of 2 mm is investigated numerically and experimentally. Pneumatic and optical methods were used to obtain distribution of static to stagnation pressure ratio along the channel axis and interferograms including the free outflow behind the channel. Modern developing discontinuous Galerkin finite element method is implemented for numerical simulation of the fluid flow. The goal to make progress in knowledge of compressible viscous fluid flow characteristic phenomena in minichannels is satisfied by finding a suitable approach to this problem. Laminar, turbulent and transitional flow regime is examined and a good agreement of experimental and numerical results is achieved using γ − Reθt transition model.
Clearance gap flow: simulations by discontinuous Galerkin method and experiments
Prausová, Helena; Bublík, Ondřej; Vimmr, Jan; Luxa, Martin; Hála, Jindřich
2015-05-01
Compressible viscous fluid flow in a narrow gap formed by two parallel plates in distance of 2 mm is investigated numerically and experimentally. Pneumatic and optical methods were used to obtain distribution of static to stagnation pressure ratio along the channel axis and interferograms including the free outflow behind the channel. Modern developing discontinuous Galerkin finite element method is implemented for numerical simulation of the fluid flow. The goal to make progress in knowledge of compressible viscous fluid flow characteristic phenomena in minichannels is satisfied by finding a suitable approach to this problem. Laminar, turbulent and transitional flow regime is examined and a good agreement of experimental and numerical results is achieved using γ - Reθt transition model.
Fiber optic liquid mass flow sensor and method
Korman, Valentin (Inventor); Gregory, Don Allen (Inventor); Wiley, John T. (Inventor); Pedersen, Kevin W. (Inventor)
2010-01-01
A method and apparatus are provided for sensing the mass flow rate of a fluid flowing through a pipe. A light beam containing plural individual wavelengths is projected from one side of the pipe across the width of the pipe so as to pass through the fluid under test. Fiber optic couplers located at least two positions on the opposite side of the pipe are used to detect the light beam. A determination is then made of the relative strengths of the light beam for each wavelength at the at least two positions and based at least in part on these relative strengths, the mass flow rate of the fluid is determined.
A particle-based method for granular flow simulation
Chang, Yuanzhang
2012-03-16
We present a new particle-based method for granular flow simulation. In the method, a new elastic stress term, which is derived from a modified form of the Hooke\\'s law, is included in the momentum governing equation to handle the friction of granular materials. Viscosity force is also added to simulate the dynamic friction for the purpose of smoothing the velocity field and further maintaining the simulation stability. Benefiting from the Lagrangian nature of the SPH method, large flow deformation can be well handled easily and naturally. In addition, a signed distance field is also employed to enforce the solid boundary condition. The experimental results show that the proposed method is effective and efficient for handling the flow of granular materials, and different kinds of granular behaviors can be well simulated by adjusting just one parameter. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.
Method of detaching adherent cells for flow cytometry
Kaur, Mandeep
2015-12-24
In one aspect, a method for detaching adherent cells can include adding a cell lifting solution to the media including a sample of adherent cells and incubating the sample of adherent cells with the cell lifting solution. No scraping or pipetting is needed to facilitate cell detachment. The method do not require inactivation of cell lifting solution and no washing of detaching cells is required to remove cell lifting solution. Detached cells can be stained with dye in the presence of cell lifting solution and are further analyzed using flow cytometer. The method has been tested using 6 different cell lines, 4 different assays, two different plate formats (96 and 384 well plates) and two different flow cytometry instruments. The method is simple to perform, less time consuming, with no cell loss and makes high throughput flow cytometry on adherent cells a reality.
Flow imaging method of electromagnetic measurement in well logging
Institute of Scientific and Technical Information of China (English)
2008-01-01
Multiphase flow in an oil well is a dynamic phenomenon of inhomogeneous medium,which should be studied in a nonlinear way. This paper presents an electromagnetic measurement method based on the electrical property differences between oil,gas and water to scan,inverse and show the distribution and condition of multiphase flow. Both numerical simulation and physical experiments have proved that clear images could be obtained by this way.
Study of the Transition Flow Regime using Monte Carlo Methods
Hassan, H. A.
1999-01-01
This NASA Cooperative Agreement presents a study of the Transition Flow Regime Using Monte Carlo Methods. The topics included in this final report are: 1) New Direct Simulation Monte Carlo (DSMC) procedures; 2) The DS3W and DS2A Programs; 3) Papers presented; 4) Miscellaneous Applications and Program Modifications; 5) Solution of Transitional Wake Flows at Mach 10; and 6) Turbulence Modeling of Shock-Dominated Fows with a k-Enstrophy Formulation.
Analysis of liposomes using asymmetrical flow field-flow fractionation
DEFF Research Database (Denmark)
Kuntsche, Judith; Decker, Christiane; Fahr, Alfred
2012-01-01
Liposomes composed of dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylglycerol were analyzed by asymmetrical flow field-flow fractionation coupled with multi-angle laser light scattering. In addition to evaluation of fractionation conditions (flow conditions, sample mass, carrier liquid......), radiolabeled drug-loaded liposomes were used to determine the liposome recovery and a potential loss of incorporated drug during fractionation. Neither sample concentration nor the cross-flow gradient distinctly affected the size results but at very low sample concentration (injected mass 5 μg) the fraction...... of larger vesicles was underestimated. Imbalance in the osmolality between the inner and outer aqueous phase resulted in liposome swelling after dilution in hypoosmotic carrier liquids. In contrast, liposome shrinking under hyperosmotic conditions was barely visible. The liposomes themselves eluted...
An update on projection methods for transient incompressible viscous flow
Energy Technology Data Exchange (ETDEWEB)
Gresho, P.M.; Chan, S.T.
1995-07-01
Introduced in 1990 was the biharmonic equation (for the pressure) and the concomitant biharmonic miracle when transient incompressible viscous flow is solved approximately by a projection method. Herein is introduced the biharmonic catastrophe that sometimes occurs with these same projection methods.
Optimization of counter flow Ranque-Hilsch vortex tube performance using Taguchi method
Energy Technology Data Exchange (ETDEWEB)
Pinar, Ahmet Murat [Celal Bayar University, Vocational High School, Department of Machinery, 45400-Turgutlu-Manisa (Turkey); Uluer, Onuralp [Gazi University, Faculty of Technical Education, Mechanical Education Department, Teknikokullar, 06503 Ankara (Turkey); Kirmaci, Volkan [Bartin University, Faculty of Engineering, Mechanical Engineering Department, 74100 Bartin (Turkey)
2009-09-15
This study discusses the application of Taguchi method in assessing maximum temperature gradient for the Ranque-Hilsch counter flow vortex tube performance. The experiments were planned based on Taguchi's L27 orthogonal array with each trial performed under different conditions of inlet pressure, nozzle number and fluid type. Signal-to-noise ratio (S/N) analysis, analysis of variance (ANOVA) and regression analysis were carried out in order to determine the effects of process parameters and optimal factor settings. Finally, confirmation tests verified that Taguchi method achieved optimization of counter flow Ranque-Hilsch vortex tube performance with sufficient accuracy. (author)
Application of Lattice Boltzmann Method to Flows in Microgeometries
Directory of Open Access Journals (Sweden)
Anoop K. Dass
2010-07-01
Full Text Available In the present investigation, Lattice Boltzmann Method (LBM is used to simulate rarefied gaseous microflows in three microgeometries. These are micro-couette, micro lid-driven cavity and micro-poiseuille flows. The Knudsen number is used to measure the degree of rarefaction in the microflows. First, micro-couette flow is computed with the effects of varying Knudsen number in the slip and threshold of the transition regime and the results compare well with existing results. After having thus established the credibility of the code and the method including boundary conditions, LBM is then used to investigate the micro lid-driven cavity flow with various aspect ratios. Simulation of microflow not only requires an appropriate method, it also requires suitable boundary conditions to provide a well-posed problem and unique solution. In this work, LBM and three slip boundary conditions, namely, diffuse scattering boundary condition, specular reflection and a combination of bounce-back and specular reflection is used to predict the micro lid-driven cavity flow fields. Then the LBM simulation is extended to micro-poiseuille flow. The results are substantiated through comparison with existing results and it is felt that the present methodology is reasonable to be employed in analyzing the flow in micro-systems.
Integral methods for shallow free-surface flows with separation
Watanabe, S; Bohr, T; Watanabe, Shinya; Putkaradze, Vachtang; Bohr, Tomas
2000-01-01
We study laminar thin film flows with large distortions in the free surface using the method of averaging across the flow. Two concrete problems are studied: the circular hydraulic jump and the flow down an inclined plane. For the circular hydraulic jump our method is able to handle an internal eddy and separated flow. Assuming a variable radial velocity profile like in Karman-Pohlhausen's method, we obtain a system of two ordinary differential equations for stationary states that can smoothly go through the jump where previous studies encountered a singularity. Solutions of the system are in good agreement with experiments. For the flow down an inclined plane we take a similar approach and derive a simple model in which the velocity profile is not restricted to a parabolic or self-similar form. Two types of solutions with large surface distortions are found: solitary, kink-like propagating fronts, obtained when the flow rate is suddenly changed, and stationary jumps, obtained, e.g., behind a sluice gate. We ...
Energy Technology Data Exchange (ETDEWEB)
Sadaoka, N.; Umegaki, K. [Hitachi, Ltd., Tokyo (Japan)
1996-01-25
A vortex-induced vibration of an array of elastically supported tubes is simulated in two-dimension by using a flow-induced vibration analysis program, which was developed in order to evaluate flow-induced vibration in various components such as heat exchangers. From a comparison of calculated results and experimental data, the following points are observed. (1) For the calculated results in a 5 {times} 5 square array, the flow pattern surrounding the first-row tubes is markedly different from that observed in the second-row or third-row tubes. This flow pattern is the same as that obtained from the experiment. (2) All tubes begin to oscillate due to unsteady fluid force and the oscillating mode is different for each row of tubes. These oscillation patterns show the same tendency in the experiments and it is concluded that the developed method can simulate vortex-induced vibration in an array of elastically supported tubes. 19 refs., 10 figs., 1 tab.
A numerical analysis of the unsteady flow past bluff bodies
Fernando, M. S. U. K.; Modi, V. J.
1990-01-01
The paper describes in detail a relatively sophisticated numerical approach, using the Boundary Element Method in conjunction with the Discrete Vortex Model, to represent the complex unsteady flow field around a bluff body with separating shear layers. Important steps in the numerical analysis of this challenging problem are discussed and a performance evaluation algorithm established. Of considerable importance is the effect of computational parameters such as number of elements representing the geometry, time-step size, location of the nascent vortices, etc., on the accuracy of results and the associated cost. As an example, the method is applied to the analysis of the flow around a stationary Savonius rotor. A detailed parametric study provides fundamental information concerning the starting torque time histories, evolution of the wake, Strouhal number, etc. A comparison with the wind tunnel test data shows remarkable correlation suggesting considerable promise for the approach.
Packet flow analysis in IP networks via abstract interpretation
Komondoor, Raghavan; Seetharam, Deva P; Balodia, Sudha
2011-01-01
Static analysis (aka offline analysis) of a model of an IP network is useful for understanding, debugging, and verifying packet flow properties of the network. There have been static analysis approaches proposed in the literature for networks based on model checking as well as graph reachability. Abstract interpretation is a method that has typically been applied to static analysis of programs. We propose a new, abstract-interpretation based approach for analysis of networks. We formalize our approach, mention its correctness guarantee, and demonstrate its flexibility in addressing multiple network-analysis problems that have been previously solved via tailor-made approaches. Finally, we investigate an application of our analysis to a novel problem -- inferring a high-level policy for the network -- which has been addressed in the past only in the restricted single-router setting.
Comparison and Validation of Hydrological E-Flow Methods through Hydrodynamic Modelling
Kuriqi, Alban; Rivaes, Rui; Sordo-Ward, Alvaro; Pinheiro, António N.; Garrote, Luis
2017-04-01
Flow regime determines physical habitat conditions and local biotic configuration. The development of environmental flow guidelines to support the river integrity is becoming a major concern in water resources management. In this study, we analysed two sites located in southern part of Portugal, respectively at Odelouca and Ocreza Rivers, characterised by the Mediterranean climate. Both rivers are almost in pristine condition, not regulated by dams or other diversion construction. This study presents an analysis of the effect on fish habitat suitability by the implementation of different hydrological e-flow methods. To conduct this study we employed certain hydrological e-flow methods recommended by the European Small Hydropower Association (ESHA). River hydrology assessment was based on approximately 30 years of mean daily flow data, provided by the Portuguese Water Information System (SNIRH). The biological data, bathymetry, physical and hydraulic features, and the Habitat Suitability Index for fish species were collected from extensive field works. We followed the Instream Flow Incremental Methodology (IFIM) to assess the flow-habitat relationship taking into account the habitat suitability of different instream flow releases. Initially, we analysed fish habitat suitability based on natural conditions, and we used it as reference condition for other scenarios considering the chosen hydrological e-flow methods. We accomplished the habitat modelling through hydrodynamic analysis by using River-2D model. The same methodology was applied to each scenario by considering as input the e-flows obtained from each of the hydrological method employed in this study. This contribution shows the significance of ecohydrological studies in establishing a foundation for water resources management actions. Keywords: ecohydrology, e-flow, Mediterranean rivers, river conservation, fish habitat, River-2D, Hydropower.
Methods in algorithmic analysis
Dobrushkin, Vladimir A
2009-01-01
…helpful to any mathematics student who wishes to acquire a background in classical probability and analysis … This is a remarkably beautiful book that would be a pleasure for a student to read, or for a teacher to make into a year's course.-Harvey Cohn, Computing Reviews, May 2010
Meshless lattice Boltzmann method for the simulation of fluid flows.
Musavi, S Hossein; Ashrafizaadeh, Mahmud
2015-02-01
A meshless lattice Boltzmann numerical method is proposed. The collision and streaming operators of the lattice Boltzmann equation are separated, as in the usual lattice Boltzmann models. While the purely local collision equation remains the same, we rewrite the streaming equation as a pure advection equation and discretize the resulting partial differential equation using the Lax-Wendroff scheme in time and the meshless local Petrov-Galerkin scheme based on augmented radial basis functions in space. The meshless feature of the proposed method makes it a more powerful lattice Boltzmann solver, especially for cases in which using meshes introduces significant numerical errors into the solution, or when improving the mesh quality is a complex and time-consuming process. Three well-known benchmark fluid flow problems, namely the plane Couette flow, the circular Couette flow, and the impulsively started cylinder flow, are simulated for the validation of the proposed method. Excellent agreement with analytical solutions or with previous experimental and numerical results in the literature is observed in all the simulations. Although the computational resources required for the meshless method per node are higher compared to that of the standard lattice Boltzmann method, it is shown that for cases in which the total number of nodes is significantly reduced, the present method actually outperforms the standard lattice Boltzmann method.
Proposed method for measurement of flow rate in turbulent periodic pipe flow
Werzner, E.; Ray, S.; Trimis, D.
2011-12-01
The present investigation deals with a previously proposed flow metering technique for laminar, fully-developed, time-periodic pipe flow. Employing knowledge of the pulsation frequency-dependent relationship between the mass flow rate and the pressure gradient, the method allows reconstruction of the instantaneous mass flow rate on the basis of a recorded pressure gradient time series. In order to explore if the procedure can be extended for turbulent flows, numerical simulations for turbulent, fully-developed, sinusoidally pulsating pipe flow with low pulse amplitude have been carried out using a ν2-f turbulence model. The study covers pulsation frequencies, ranging from the quasi-steady up to the inertia-dominated frequency regime, and three cycle-averaged Reynolds numbers of 4360, 9750 and 15400. After providing the theoretical background of the flow rate reconstruction principle, the numerical model and an experimental facility for the verification of simulations are explained. The obtained results, presented in time and frequency domain, show good agreement with each other and indicate a frequency dependence, similar to that used for the signal reconstruction for laminar flows. A modified dimensionless frequency definition has been introduced, which allows a generalised representation of the results considering the influence of Reynolds number.
Analysis of Secondary Flows in Centrifugal Impellers
2005-01-01
Secondary flows are undesirable in centrifugal compressors as they are a direct cause for flow (head) losses, create nonuniform meridional flow profiles, potentially induce flow separation/stall, and contribute to impeller flow slip; that is, secondary flows negatively affect the compressor performance. A model based on the vorticity equation for a rotating system was developed to determine the streamwise vorticity from the normal and binormal vorticity components (which are known from the me...
Institute of Scientific and Technical Information of China (English)
赵芝梅; 王敏庆
2012-01-01
For the analysis of plate-shell coupled structures, the coupling edges should be divided by lots of points to calculate if the substructure point receptance method is applied, which is inconvenient. To solve this problem, an improved substructure line receptance method is presented here. Firstly, a coupled model of a cylindrical shell with a floor partition is obtained, based on the substructure theory. Secondly, a modal expansion method is utilized to get the line receptance of the cylindrical shell and the floor partition separately. As a result, vibrating velocities of the plate and the shell can be acquired, to calculate the power flows of the system. Eventually, comparison is carried out among the results calculated by substructure line receptance methods, ANSYS and AutoSEA, respectively. It shows that the method presented here is effective to analyze the vibration power flow characteristics of plate-shell coupled structures over a wide frequency range and the calculation process is simpler compared with that of the substructure point mobility method. Thus, this method is especially suitable for complex structures coupled with lines.%采用子结构点导纳方法分析铺壳耦合结构振动特性时，需要将衔接线划分为一系列的点进行求解，较为烦琐。针对这一问题，该文提出了改进的子结构线导纳方法。首先建立了铺板和圆柱壳的耦合振动模型；然后采用模态展开法分别求解铺板和圆柱壳的机械线导纳，得到振动传递方程中的线导纳矩阵；最后求解耦合振动方程分析铺板与圆柱壳的振动功率流特性。将结果分别与ANSYS和AutoSEA的计算结果进行对比分析表明：该文提出的改进方法能够在宽频带内有效地计算板壳耦合结构的振动功率流特性，且求解过程简单，适于线衔接复杂结构的振动特性分析。
Air-segmented amplitude-modulated multiplexed flow analysis.
Inui, Koji; Uemura, Takeshi; Ogusu, Takeshi; Takeuchi, Masaki; Tanaka, Hideji
2011-01-01
Air-segmentation is applied to amplitude-modulated multiplexed flow analysis, which we proposed recently. Sample solutions, the flow rates of which are varied periodically, are merged with reagent and/or diluent solution. The merged stream is segmented by air-bubbles and, downstream, its absorbance is measured after deaeration. The analytes in the samples are quantified from the amplitudes of the respective wave components in the absorbance. The proposed method is applied to the determinations of a food dye, phosphate ions and nitrite ions. The air-segmentation is effective for limiting amplitude damping through the axial dispersion, resulting in an improvement in sensitivity. This effect is more pronounced at shorter control periods and longer flow path lengths.
Mixed exhaust flow supersonic jet engine and method
Energy Technology Data Exchange (ETDEWEB)
Klees, G.W.
1993-06-08
A method of operating a supersonic jet engine installation is described comprising (a) providing an engine having a variable area air inlet means and an outlet to discharge engine exhaust; (b) providing a secondary air passageway means; (c) receiving ambient air in the air inlet means and providing the ambient air as primary air to the engine inlet and secondary air to the secondary air passageway means; (d) providing a mixing section having an inlet portion and an exit portion, utilizing the mixing section in directing the exhaust from the engine to primary convergent/divergent exit passageway segments, where the exhaust is discharged at supersonic velocity as primary flow components, and directing secondary air flow from the secondary air passageway means to secondary exit passageway segments which are interspersed with the primary segments and from which the secondary air is discharged at subsonic velocity as secondary flow components; and (e) providing an exhaust section to receive the primary and secondary flow components in a mixing region and causing the primary and secondary flow components to mix to create a supersonic mixed flow, the exhaust section having a variable area final nozzle through which the mixed flow is discharged.
Detection of Abnormal Events via Optical Flow Feature Analysis
Directory of Open Access Journals (Sweden)
Tian Wang
2015-03-01
Full Text Available In this paper, a novel algorithm is proposed to detect abnormal events in video streams. The algorithm is based on the histogram of the optical flow orientation descriptor and the classification method. The details of the histogram of the optical flow orientation descriptor are illustrated for describing movement information of the global video frame or foreground frame. By combining one-class support vector machine and kernel principal component analysis methods, the abnormal events in the current frame can be detected after a learning period characterizing normal behaviors. The difference abnormal detection results are analyzed and explained. The proposed detection method is tested on benchmark datasets, then the experimental results show the effectiveness of the algorithm.
A novel restricted-flow etching method for glass
Institute of Scientific and Technical Information of China (English)
Hai-bo XIE; Yi ZHENG; Yu-run FAN; Xin FU; Hua-yong YANG
2009-01-01
This paper presents a novel micro fabrication method based on the laminar characteristics of micro-scale flows. Therein the separator and etchant are alternatively arranged in micro channels to form multiple laminar streams, and the etchant is located at the site where the reaction is supposed to occur. This new micro fabrication process can be used for the high aspect ratio etching inside a microchannel on glass substrates. Furthermore, the topography of microstructure patterned by this method can be controlled by changing the flow parameters of the separator and etchant. Experiments on the effects of flow parameters on the aspect ratio, side wall profile and etching rate were carried out on a glass substrate. The effect of flow rates on the etching rate and the micro topography was analyzed, in addition, experiments with dynamical changes of the flow rate ratio of the separator and etchant showed that the verticality of the side walls of microstructures can be significantly improved. The restricted flowing etching technique not only abates the isotropic effect in the traditional wet etching but also significantly reduces the dependence on expensive photolithographic equipment.
Simulating High Reynolds Number Flow by Lattice Boltzmann Method
Institute of Scientific and Technical Information of China (English)
KANG Xiu-Ying; LIU Da-He; ZHOU Jing; JIN Yong-Juan
2005-01-01
@@ A two-dimensional channel flow with different Reynolds numbers is tested by using the lattice Boltzmann method under different pressure and velocity boundary conditions. The results show that the simulation error increases,and the pressure and the flow rate become unstable under a high Reynolds number. To improve the simulation precision under a high Reynolds number, the number of fluid nodes should be enlarged. For a higher Reynoldsnumber flow, the velocity boundary with an approximately parabolic velocity profile is found to be more adaptive.Blood flow in an artery with cosine shape symmetrical narrowing is then simulated under a velocity boundary condition. Its velocity, pressure and wall shear stress distributions are consistent with previous studies.
Improved numerical methods for turbulent viscous recirculating flows
Turan, A.; Vandoormaal, J. P.
1988-01-01
The performance of discrete methods for the prediction of fluid flows can be enhanced by improving the convergence rate of solvers and by increasing the accuracy of the discrete representation of the equations of motion. This report evaluates the gains in solver performance that are available when various acceleration methods are applied. Various discretizations are also examined and two are recommended because of their accuracy and robustness. Insertion of the improved discretization and solver accelerator into a TEACH mode, that has been widely applied to combustor flows, illustrates the substantial gains to be achieved.
An eddy viscosity calculation method for a turbulent duct flow
Antonia, R. A.; Bisset, D. K.; Kim, J.
1991-01-01
The mean velocity profile across a fully developed turbulent duct flow is obtained from an eddy viscosity relation combined with an empirical outer region wake function. Results are in good agreement with experiments and with direct numerical simulations in the same flow at two Reynolds numbers. In particular, the near-wall trend of the Reynolds shear stress and its variation with Reynolds number are similar to those of the simulations. The eddy viscosity method is more accurate than previous mixing length or implicit function methods.
Systems and methods for rebalancing redox flow battery electrolytes
Pham, Ai Quoc; Chang, On Kok
2015-03-17
Various methods of rebalancing electrolytes in a redox flow battery system include various systems using a catalyzed hydrogen rebalance cell configured to minimize the risk of dissolved catalyst negatively affecting flow battery performance. Some systems described herein reduce the chance of catalyst contamination of RFB electrolytes by employing a mediator solution to eliminate direct contact between the catalyzed membrane and the RFB electrolyte. Other methods use a rebalance cell chemistry that maintains the catalyzed electrode at a potential low enough to prevent the catalyst from dissolving.
Continuous-flow free acid monitoring method and system
Strain, J.E.; Ross, H.H.
1980-01-11
A free acid monitoring method and apparatus is provided for continuously measuring the excess acid present in a process stream. The disclosed monitoring system and method is based on the relationship of the partial pressure ratio of water and acid in equilibrium with an acid solution at constant temperature. A portion of the process stream is pumped into and flows through the monitor under the influence of gravity and back to the process stream. A continuous flowing sample is vaporized at a constant temperature and the vapor is subsequently condensed. Conductivity measurements of the condensate produces a nonlinear response function from which the free acid molarity of the sample process stream is determined.
A Level Set Discontinuous Galerkin Method for Free Surface Flows
DEFF Research Database (Denmark)
Grooss, Jesper; Hesthaven, Jan
2006-01-01
We present a discontinuous Galerkin method on a fully unstructured grid for the modeling of unsteady incompressible fluid flows with free surfaces. The surface is modeled by embedding and represented by a levelset. We discuss the discretization of the flow equations and the level set equation...... as well a various ways of advancing the equations in time using velocity projection techniques. The efficacy of the method for the representation of the levelset and its reinitialization is discussed and several numerical tests confirm the robustness and versatility of the proposed scheme....
Comparison of clustering methods for high-dimensional single-cell flow and mass cytometry data.
Weber, Lukas M; Robinson, Mark D
2016-12-01
Recent technological developments in high-dimensional flow cytometry and mass cytometry (CyTOF) have made it possible to detect expression levels of dozens of protein markers in thousands of cells per second, allowing cell populations to be characterized in unprecedented detail. Traditional data analysis by "manual gating" can be inefficient and unreliable in these high-dimensional settings, which has led to the development of a large number of automated analysis methods. Methods designed for unsupervised analysis use specialized clustering algorithms to detect and define cell populations for further downstream analysis. Here, we have performed an up-to-date, extensible performance comparison of clustering methods for high-dimensional flow and mass cytometry data. We evaluated methods using several publicly available data sets from experiments in immunology, containing both major and rare cell populations, with cell population identities from expert manual gating as the reference standard. Several methods performed well, including FlowSOM, X-shift, PhenoGraph, Rclusterpp, and flowMeans. Among these, FlowSOM had extremely fast runtimes, making this method well-suited for interactive, exploratory analysis of large, high-dimensional data sets on a standard laptop or desktop computer. These results extend previously published comparisons by focusing on high-dimensional data and including new methods developed for CyTOF data. R scripts to reproduce all analyses are available from GitHub (https://github.com/lmweber/cytometry-clustering-comparison), and pre-processed data files are available from FlowRepository (FR-FCM-ZZPH), allowing our comparisons to be extended to include new clustering methods and reference data sets. © 2016 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of ISAC.
Outlier Detection Method Use for the Network Flow Anomaly Detection
Directory of Open Access Journals (Sweden)
Rimas Ciplinskas
2016-06-01
Full Text Available New and existing methods of cyber-attack detection are constantly being developed and improved because there is a great number of attacks and the demand to protect from them. In prac-tice, current methods of attack detection operates like antivirus programs, i. e. known attacks signatures are created and attacks are detected by using them. These methods have a drawback – they cannot detect new attacks. As a solution, anomaly detection methods are used. They allow to detect deviations from normal network behaviour that may show a new type of attack. This article introduces a new method that allows to detect network flow anomalies by using local outlier factor algorithm. Accom-plished research allowed to identify groups of features which showed the best results of anomaly flow detection according the highest values of precision, recall and F-measure.
Institute of Scientific and Technical Information of China (English)
CHENG Wen; MURAI Yuichi; SASAKI Toshio; YAMAMOTO Fujio
2004-01-01
An inverse analysis algorithm is proposed for estimating liquid phase flow field from measurement data of bubble motion. This kind of technology will be applied in future for various estimation of fluid flow in rivers, lakes, sea surface flow, and also microscopic channel flow as the problem-handling in civil, mechanical, electronic, and chemical engineering. The relationship between the dispersion motion and the carrier phase flow is governed and expressed by the translational motion equation of spherical dispersion. The equation consists of all the force components including inertia, added inertia, drag, lift, pressure gradient force and gravity force. Using this equation enables us to estimate the carrier phase flow structure using only the data of the dispersion motion. Whole field liquid flow structure is also estimated using spatial or temporal interpolation method. In order to verify this principle, the Taylor-Green vortex flow, and the Karman vortex shedding from a square cylinder have been chosen. The results show that the combination of the inverse analysis and Particle Tracking Velocimetry (PTV) with the spatio-temporal post-processing algorithm could reconstruct well the carrier phase flow of the gas-liquid two-phase flow.
Witzke, V; Favier, B
2016-01-01
Shear flows are ubiquitous in astrophysical objects including planetary and stellar interiors, where their dynamics can have significant impact on thermo-chemical processes. Investigating the complex dynamics of shear flows requires numerical calculations that provide a long time evolution of the system. To achieve a sufficiently long lifetime in a local numerical model the system has to be forced externally. However, at present, there exist several different forcing methods to sustain large-scale shear flows in local models. In this paper we examine and compare various methods used in the literature in order to resolve their respective applicability and limitations. These techniques are compared during the exponential growth phase of a shear flow instability, such as the Kelvin-Helmholtz (KH) instability, and some are examined during the subsequent non-linear evolution. A linear stability analysis provides reference for the growth rate of the most unstable modes in the system and a detailed analysis of the e...
Socioeconomic Methods in Educational Analysis.
Weber, William H., III
This book explores the possibilities in a new approach to educational analysis--a fusion of methods drawn from economics, sociology, and social psychology. The author combines his explanation of socioeconomic analysis with the presentation of several examples that illustrate the application of his method to different analytical problems. The book…
Stochastic simulation of fluid flow in porous media by the complex variable expression method
Institute of Scientific and Technical Information of China (English)
SONG Hui-bin; ZHAN Mei-li; SHENG Jin-chang; LUO Yu-long
2013-01-01
A stochastic simulation of fluid flow in porous media using a complex variable expression method (SFCM) is presented in this paper.Hydraulic conductivity is considered as a random variable and is then expressed in complex variable form,the real part of which is a deterministic value and the imaginary part is a variable value.The stochastic seepage flow is simulated with the SFCM and is compared with the results calculated with the Monte Carlo stochastic finite element method.In using the Monte Carlo method to simulate the stochastic seepage flow field,the hydraulic conductivity is assumed in three different probability distributions using random sampling method.The obtained seepage flow field is examined through skewness analysis,and the skewed distribution probability density function is given.The head mode value and the head comprehensive standard deviation are used to represent the sta-tistics of calculation results obtained by the Monte Carlo method.The stochastic seepage flow field simulated by the SFCM is confirmed to be similar to that given by the Monte Carlo method from numerical aspects.The range of coefficient of variation of hydraulic conductivity in SFCM is larger than used previously in stochastic seepage flow field simulations,and the computation time is short.The results proved that the SFCM is a convenient calculating method for solving the complex problems.
A Panel Method for the Potential Flow Around 2-D Hydrofoils
BAL, Şakir
1999-01-01
A potential-based panel method for the hydrodynamic analysis of 2-D hydrofoils moving under a free surface with constant speed without consideration of the cavitation phenomenon is described. By applying Green's theorem and choosing the value of internal potential as equal to the incoming flow potential, an integral equation for the total potential is obtained under the potential flow theory. The free surface condition is linearized and the Dirichlet boundary condition is used i...
River Flow Prediction Using the Nearest Neighbor Probabilistic Ensemble Method
Directory of Open Access Journals (Sweden)
H. Sanikhani
2016-02-01
Full Text Available Introduction: In the recent years, researchers interested on probabilistic forecasting of hydrologic variables such river flow.A probabilistic approach aims at quantifying the prediction reliability through a probability distribution function or a prediction interval for the unknown future value. The evaluation of the uncertainty associated to the forecast is seen as a fundamental information, not only to correctly assess the prediction, but also to compare forecasts from different methods and to evaluate actions and decisions conditionally on the expected values. Several probabilistic approaches have been proposed in the literature, including (1 methods that use resampling techniques to assess parameter and model uncertainty, such as the Metropolis algorithm or the Generalized Likelihood Uncertainty Estimation (GLUE methodology for an application to runoff prediction, (2 methods based on processing the forecast errors of past data to produce the probability distributions of future values and (3 methods that evaluate how the uncertainty propagates from the rainfall forecast to the river discharge prediction, as the Bayesian forecasting system. Materials and Methods: In this study, two different probabilistic methods are used for river flow prediction.Then the uncertainty related to the forecast is quantified. One approach is based on linear predictors and in the other, nearest neighbor was used. The nonlinear probabilistic ensemble can be used for nonlinear time series analysis using locally linear predictors, while NNPE utilize a method adapted for one step ahead nearest neighbor methods. In this regard, daily river discharge (twelve years of Dizaj and Mashin Stations on Baranduz-Chay basin in west Azerbijan and Zard-River basin in Khouzestan provinces were used, respectively. The first six years of data was applied for fitting the model. The next three years was used to calibration and the remained three yeas utilized for testing the models
Clustering as an EDA Method: The Case of Pedestrian Directional Flow Behavior
Directory of Open Access Journals (Sweden)
Ma. Regina E. Estuar
2010-01-01
Full Text Available Given the data of pedestrian trajectories in NTXY format, three clustering methods of K Means, Expectation Maximization (EM and Affinity Propagation were utilized as Exploratory Data Analysis to find the pattern of pedestrian directional flow behavior. The analysis begins without a prior notion regarding the structure of the pattern and it consequentially infers the structure of directional flow pattern. Significant similarities in patterns for both individual and instantaneous walking angles based on EDA method are reported and explained in case studies
A new method for flow measurement in cryogenic systems
Grohmann, S.
2014-03-01
A new method for mass flow measurement of fluids in pipes is presented; its novelty lies in the capability for intrinsic calibration. The method is founded on a concept, where two independent analytic expressions for the flow rate are formed from the same direct measurement readings (input parameters). If the input parameters were error-free, the two expressions would yield identical results, by definition. This fact can be used as goal function in a minimization routine that removes systematic errors of the inherently error-prone input parameters. The uncertainty of the mass flow measurement is then only influenced by statistical effects and is typically less than 1% with regard to the measured value. The new method is explained by a proof-of-principle that is based on measurements in a large-scale cryogenic system. The intrinsic calibrations can be executed in situ at any moment during operation of a plant, and with no need for a reference standard. While the new method is applicable in any system involving single-phase fluid flow, it offers particular advantages in cryogenic application.
Space-time discontinuous Galerkin method for compressible flow
Klaij, C.M.
2006-01-01
The space-time discontinuous Galerkin method allows the simulation of compressible flow in complex aerodynamical applications requiring moving, deforming and locally refined meshes. This thesis contains the space-time discretization of the physical model, a fully explicit solver for the resulting
Vortex Analysis of Intra-Aneurismal Flow in Cerebral Aneurysms
Directory of Open Access Journals (Sweden)
Kevin Sunderland
2016-01-01
Full Text Available This study aims to develop an alternative vortex analysis method by measuring structure ofIntracranial aneurysm (IA flow vortexes across the cardiac cycle, to quantify temporal stability of aneurismal flow. Hemodynamics were modeled in “patient-specific” geometries, using computational fluid dynamics (CFD simulations. Modified versions of known λ2 and Q-criterion methods identified vortex regions; then regions were segmented out using the classical marching cube algorithm. Temporal stability was measured by the degree of vortex overlap (DVO at each step of a cardiac cycle against a cycle-averaged vortex and by the change in number of cores over the cycle. No statistical differences exist in DVO or number of vortex cores between 5 terminal IAs and 5 sidewall IAs. No strong correlation exists between vortex core characteristics and geometric or hemodynamic characteristics of IAs. Statistical independence suggests this proposed method may provide novel IA information. However, threshold values used to determine the vortex core regions and resolution of velocity data influenced analysis outcomes and have to be addressed in future studies. In conclusions, preliminary results show that the proposed methodology may help give novel insight toward aneurismal flow characteristic and help in future risk assessment given more developments.
Vortex Analysis of Intra-Aneurismal Flow in Cerebral Aneurysms
Sunderland, Kevin; Haferman, Christopher; Chintalapani, Gouthami
2016-01-01
This study aims to develop an alternative vortex analysis method by measuring structure ofIntracranial aneurysm (IA) flow vortexes across the cardiac cycle, to quantify temporal stability of aneurismal flow. Hemodynamics were modeled in “patient-specific” geometries, using computational fluid dynamics (CFD) simulations. Modified versions of known λ2 and Q-criterion methods identified vortex regions; then regions were segmented out using the classical marching cube algorithm. Temporal stability was measured by the degree of vortex overlap (DVO) at each step of a cardiac cycle against a cycle-averaged vortex and by the change in number of cores over the cycle. No statistical differences exist in DVO or number of vortex cores between 5 terminal IAs and 5 sidewall IAs. No strong correlation exists between vortex core characteristics and geometric or hemodynamic characteristics of IAs. Statistical independence suggests this proposed method may provide novel IA information. However, threshold values used to determine the vortex core regions and resolution of velocity data influenced analysis outcomes and have to be addressed in future studies. In conclusions, preliminary results show that the proposed methodology may help give novel insight toward aneurismal flow characteristic and help in future risk assessment given more developments. PMID:27891172
Dual Solutions for Nonlinear Flow Using Lie Group Analysis.
Directory of Open Access Journals (Sweden)
Muhammad Awais
Full Text Available `The aim of this analysis is to investigate the existence of the dual solutions for magnetohydrodynamic (MHD flow of an upper-convected Maxwell (UCM fluid over a porous shrinking wall. We have employed the Lie group analysis for the simplification of the nonlinear differential system and computed the absolute invariants explicitly. An efficient numerical technique namely the shooting method has been employed for the constructions of solutions. Dual solutions are computed for velocity profile of an upper-convected Maxwell (UCM fluid flow. Plots reflecting the impact of dual solutions for the variations of Deborah number, Hartman number, wall mass transfer are presented and analyzed. Streamlines are also plotted for the wall mass transfer effects when suction and blowing situations are considered.
Data-flow Analysis of Programs with Associative Arrays
Directory of Open Access Journals (Sweden)
David Hauzar
2014-05-01
Full Text Available Dynamic programming languages, such as PHP, JavaScript, and Python, provide built-in data structures including associative arrays and objects with similar semantics—object properties can be created at run-time and accessed via arbitrary expressions. While a high level of security and safety of applications written in these languages can be of a particular importance (consider a web application storing sensitive data and providing its functionality worldwide, dynamic data structures pose significant challenges for data-flow analysis making traditional static verification methods both unsound and imprecise. In this paper, we propose a sound and precise approach for value and points-to analysis of programs with associative arrays-like data structures, upon which data-flow analyses can be built. We implemented our approach in a web-application domain—in an analyzer of PHP code.
Dual Solutions for Nonlinear Flow Using Lie Group Analysis.
Awais, Muhammad; Hayat, Tasawar; Irum, Sania; Saleem, Salman
2015-01-01
`The aim of this analysis is to investigate the existence of the dual solutions for magnetohydrodynamic (MHD) flow of an upper-convected Maxwell (UCM) fluid over a porous shrinking wall. We have employed the Lie group analysis for the simplification of the nonlinear differential system and computed the absolute invariants explicitly. An efficient numerical technique namely the shooting method has been employed for the constructions of solutions. Dual solutions are computed for velocity profile of an upper-convected Maxwell (UCM) fluid flow. Plots reflecting the impact of dual solutions for the variations of Deborah number, Hartman number, wall mass transfer are presented and analyzed. Streamlines are also plotted for the wall mass transfer effects when suction and blowing situations are considered.
Kawahara, Mutsuto
2016-01-01
This book focuses on the finite element method in fluid flows. It is targeted at researchers, from those just starting out up to practitioners with some experience. Part I is devoted to the beginners who are already familiar with elementary calculus. Precise concepts of the finite element method remitted in the field of analysis of fluid flow are stated, starting with spring structures, which are most suitable to show the concepts of superposition/assembling. Pipeline system and potential flow sections show the linear problem. The advection–diffusion section presents the time-dependent problem; mixed interpolation is explained using creeping flows, and elementary computer programs by FORTRAN are included. Part II provides information on recent computational methods and their applications to practical problems. Theories of Streamline-Upwind/Petrov–Galerkin (SUPG) formulation, characteristic formulation, and Arbitrary Lagrangian–Eulerian (ALE) formulation and others are presented with practical results so...
A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels
Huajun Li; Haifeng Ji; Zhiyao Huang; Baoliang Wang; Haiqing Li; Guohua Wu
2016-01-01
Based on a laser diode, a 12 × 6 photodiode array sensor, and machine learning techniques, a new void fraction measurement method for gas-liquid two-phase flow in small channels is proposed. To overcome the influence of flow pattern on the void fraction measurement, the flow pattern of the two-phase flow is firstly identified by Fisher Discriminant Analysis (FDA). Then, according to the identification result, a relevant void fraction measurement model which is developed by Support Vector Mach...
Flow boiling in microgap channels experiment, visualization and analysis
Alam, Tamanna; Jin, Li-Wen
2013-01-01
Flow Boiling in Microgap Channels: Experiment, Visualization and Analysis presents an up-to-date summary of the details of the confined to unconfined flow boiling transition criteria, flow boiling heat transfer and pressure drop characteristics, instability characteristics, two phase flow pattern and flow regime map and the parametric study of microgap dimension. Advantages of flow boiling in microgaps over microchannels are also highlighted. The objective of this Brief is to obtain a better fundamental understanding of the flow boiling processes, compare the performance between microgap and c
Stochastic uncertainty analysis for unconfined flow systems
Liu, Gaisheng; Zhang, Dongxiao; Lu, Zhiming
2006-01-01
A new stochastic approach proposed by Zhang and Lu (2004), called the Karhunen-Loeve decomposition-based moment equation (KLME), has been extended to solving nonlinear, unconfined flow problems in randomly heterogeneous aquifers. This approach is on the basis of an innovative combination of Karhunen-Loeve decomposition, polynomial expansion, and perturbation methods. The random log-transformed hydraulic conductivity field (InKS) is first expanded into a series in terms of orthogonal Gaussian standard random variables with their coefficients obtained as the eigenvalues and eigenfunctions of the covariance function of InKS- Next, head h is decomposed as a perturbation expansion series ??A(m), where A(m) represents the mth-order head term with respect to the standard deviation of InKS. Then A(m) is further expanded into a polynomial series of m products of orthogonal Gaussian standard random variables whose coefficients Ai1,i2(m)...,im are deterministic and solved sequentially from low to high expansion orders using MODFLOW-2000. Finally, the statistics of head and flux are computed using simple algebraic operations on Ai1,i2(m)...,im. A series of numerical test results in 2-D and 3-D unconfined flow systems indicated that the KLME approach is effective in estimating the mean and (co)variance of both heads and fluxes and requires much less computational effort as compared to the traditional Monte Carlo simulation technique. Copyright 2006 by the American Geophysical Union.
Rain-Flow and Reverse Rain-Flow Counting Method for the Compilation of Fatigue Load Spectrum
Institute of Scientific and Technical Information of China (English)
宋玉普; 李朝阳; 王立成
2001-01-01
The rain-flow counting method is widely used to compile the fatigue load spectrum. The second stage counting of the rain-flow method is a troublesome process. In order to overcome this drawback, the rain-flow and reverse rain-flow counting method is proposed in this paper. In this counting method, the rule for counting of the rain-flow method is modified, so that the sequence of load-time need not be adjusted. This is a valid and useful method to count cycles and compile the load spectrum and it can be widely used in ocean engineering.
Adaptive Spectral Estimation Methods in Color Flow Imaging.
Karabiyik, Yucel; Ekroll, Ingvild Kinn; Eik-Nes, Sturla H; Avdal, Jorgen; Lovstakken, Lasse
2016-11-01
Clutter rejection for color flow imaging (CFI) remains a challenge due to either a limited amount of temporal samples available or nonstationary tissue clutter. This is particularly the case for interleaved CFI and B-mode acquisitions. Low velocity blood signal is attenuated along with the clutter due to the long transition band of the available clutter filters, causing regions of biased mean velocity estimates or signal dropouts. This paper investigates how adaptive spectral estimation methods, Capon and blood iterative adaptive approach (BIAA), can be used to estimate the mean velocity in CFI without prior clutter filtering. The approach is based on confining the clutter signal in a narrow spectral region around the zero Doppler frequency while keeping the spectral side lobes below the blood signal level, allowing for the clutter signal to be removed by thresholding in the frequency domain. The proposed methods are evaluated using computer simulations, flow phantom experiments, and in vivo recordings from the common carotid and jugular vein of healthy volunteers. Capon and BIAA methods could estimate low blood velocities, which are normally attenuated by polynomial regression filters, and may potentially give better estimation of mean velocities for CFI at a higher computational cost. The Capon method decreased the bias by 81% in the transition band of the used polynomial regression filter for small packet size ( N=8 ) and low SNR (5 dB). Flow phantom and in vivo results demonstrate that the Capon method can provide color flow images and flow profiles with lower variance and bias especially in the regions close to the artery walls.
Simple numerical method for predicting steady compressible flows
Vonlavante, Ernst; Nelson, N. Duane
1986-01-01
A numerical method for solving the isenthalpic form of the governing equations for compressible viscous and inviscid flows was developed. The method was based on the concept of flux vector splitting in its implicit form. The method was tested on several demanding inviscid and viscous configurations. Two different forms of the implicit operator were investigated. The time marching to steady state was accelerated by the implementation of the multigrid procedure. Its various forms very effectively increased the rate of convergence of the present scheme. High quality steady state results were obtained in most of the test cases; these required only short computational times due to the relative efficiency of the basic method.
Characteristic particle methods for traffic flow simulations on highway networks
Farjoun, Yossi
2012-01-01
A characteristic particle method for the simulation of first order macroscopic traffic models on road networks is presented. The approach is based on the method "particleclaw", which solves scalar one dimensional hyperbolic conservations laws exactly, except for a small error right around shocks. The method is generalized to nonlinear network flows, where particle approximations on the edges are suitably coupled together at the network nodes. It is demonstrated in numerical examples that the resulting particle method can approximate traffic jams accurately, while only devoting a few degrees of freedom to each edge of the network.
Traffic Flow Management Using Aggregate Flow Models and the Development of Disaggregation Methods
Sun, Dengfeng; Sridhar, Banavar; Grabbe, Shon
2010-01-01
A linear time-varying aggregate traffic flow model can be used to develop Traffic Flow Management (tfm) strategies based on optimization algorithms. However, there are no methods available in the literature to translate these aggregate solutions into actions involving individual aircraft. This paper describes and implements a computationally efficient disaggregation algorithm, which converts an aggregate (flow-based) solution to a flight-specific control action. Numerical results generated by the optimization method and the disaggregation algorithm are presented and illustrated by applying them to generate TFM schedules for a typical day in the U.S. National Airspace System. The results show that the disaggregation algorithm generates control actions for individual flights while keeping the air traffic behavior very close to the optimal solution.
Studies of the analyte-carrier interface in flow injection analysis
Energy Technology Data Exchange (ETDEWEB)
Brown, S.D.
1992-01-01
Chemical analysis in flowing solution is popular for automation of classical methods. However, most of the classical methods are not specific enough for direct multicomponent analysis of simple mixtures. This research project has the goals of study of rapid multicomponent analysis of transient species in flowing media, and investigations of chemical reactions at interfaces and of effects of competition on distribution of products from interfacial reaction. This report summarizes work done over the past 4.5 years; support has been terminated.
Trace projection transformation: a new method for measurement of debris flow surface velocity fields
Yan, Yan; Cui, Peng; Guo, Xiaojun; Ge, Yonggang
2016-12-01
Spatiotemporal variation of velocity is important for debris flow dynamics. This paper presents a new method, the trace projection transformation, for accurate, non-contact measurement of a debris-flow surface velocity field based on a combination of dense optical flow and perspective projection transformation. The algorithm for interpreting and processing is implemented in C ++ and realized in Visual Studio 2012. The method allows quantitative analysis of flow motion through videos from various angles (camera positioned at the opposite direction of fluid motion). It yields the spatiotemporal distribution of surface velocity field at pixel level and thus provides a quantitative description of the surface processes. The trace projection transformation is superior to conventional measurement methods in that it obtains the full surface velocity field by computing the optical flow of all pixels. The result achieves a 90% accuracy of when comparing with the observed values. As a case study, the method is applied to the quantitative analysis of surface velocity field of a specific debris flow.
A review of current finite difference rotor flow methods
Caradonna, F. X.; Tung, C.
1986-01-01
Rotary-wing computational fluid dynamics is reaching a point where many three-dimensional, unsteady, finite-difference codes are becoming available. This paper gives a brief review of five such codes, which treat the small disturbance, conservative and nonconservative full-potential, and Euler flow models. A discussion of the methods of applying these codes to the rotor environment (including wake and trim considerations) is followed by a comparison with various available data. These data include tests of advancing lifting and nonlifting, and hovering model rotors with significant supercritical flow regions. The codes are also compared for computational efficiency.
Computation of Load Flow Problems with Homotopy Methods
Institute of Scientific and Technical Information of China (English)
陈玉荣; 蔡大用
2001-01-01
Load flow computations are the basis for voltage security assessments in power systems. All of theflow equation solutions must be computed to explore the mechanisms of voltage instability and voltagecollapse. Conventional algorithms, such as Newton's methods and its variations, are not very desirablebecause they can not be easily used to find all of the solutions. This paper investigates homotopy methodswhich can be used for numerically computing the set of all isolated solutions of multivariate polynomial systemsresulting from load flow computations. The results significantly reduce the number of paths being followed.``
Jiménez-Hornero, Francisco J.; Ariza-Villaverde, Ana B.; de Ravé, Eduardo Gutiérrez
2013-03-01
The spatial description of flows in porous media is a main issue due to their influence on processes that take place inside. In addition to descriptive statistics, the multifractal analysis based on the Box-Counting fixed-size method has been used during last decade to study some porous media features. However, this method gives emphasis to domain regions containing few data points that spark the biased assessment of generalized fractal dimensions for negative moment orders. This circumstance is relevant when describing the flow velocity field in idealised three-dimensional porous media. The application of the Sandbox method is explored in this work as an alternative to the Box-Counting procedure for analyzing flow velocity magnitude simulated with the lattice model approach for six media with different porosities. According to the results, simulated flows have multiscaling behaviour. The multifractal spectra obtained with the Sandbox method reveal more heterogeneity as well as the presence of some extreme values in the distribution of high flow velocity magnitudes as porosity decreases. This situation is not so evident for the multifractal spectra estimated with the Box-Counting method. As a consequence, the description of the influence of porous media structure on flow velocity distribution provided by the Sandbox method improves the results obtained with the Box-Counting procedure.
Field-Flow Fractionation Analysis of Complex Biological Samples
Directory of Open Access Journals (Sweden)
Mijić, I.
2014-03-01
Full Text Available Normal analytical methods have difficulties when analysing complex samples containing particles of different size. In the 1960s, a new analytical technique was developed, which was able to overcome those difficulties. This new, Field-Flow Fractionation (FFF technique has been primarily used in the separation of large particles such as macromolecules and colloids. The development and improvement of the FFF technique led to the coupling of the technique with other specific and sensitive analytical methods which resulted in the FFF technique becoming very useful in isolation, separation and analysis of various complex samples, such as powders, emulsions, colloids, geological sediments, biopolymers, complex proteins, polysaccharides, synthetic polymers, and many others. The separation field in the FFF technique is a thin, empty flow chamber called a channel. The structure of the ribbonlike channel with view of the parabolic flow can be seen in Fig. 1. Separation is achieved by the interaction of sample components with an externally generated field, which is applied perpendicularly to the direction of the mobile flow inside the channel. Sample components, which differ in molar mass, size or other properties are pushed by the applied perpendicular field into different velocity regions within the parabolic flow profile of the mobile phase across the channel. The flow has different velocity depending on the position within the channel; the velocity at the walls is zero and it increases towards the centre of the channel. Samples are carried downstream through the channel at different velocities and exit the channel after different retention times. The relative distribution of samples in the parabolic flow determines the separation characteristics. Different operating modes have different types of distributions. The most frequently used mechanisms of FFF separation are listed in Fig. 2. Based on the characteristics of analysed particles and applied outer
Directory of Open Access Journals (Sweden)
Vendula Pospichalova
2015-03-01
Full Text Available Flow cytometry is a powerful method, which is widely used for high-throughput quantitative and qualitative analysis of cells. However, its straightforward applicability for extracellular vesicles (EVs and mainly exosomes is hampered by several challenges, reflecting mostly the small size of these vesicles (exosomes: ~80–200 nm, microvesicles: ~200–1,000 nm, their polydispersity, and low refractive index. The current best and most widely used protocol for beads-free flow cytometry of exosomes uses ultracentrifugation (UC coupled with floatation in sucrose gradient for their isolation, labeling with lipophilic dye PKH67 and antibodies, and an optimized version of commercial high-end cytometer for analysis. However, this approach requires an experienced flow cytometer operator capable of manual hardware adjustments and calibration of the cytometer. Here, we provide a novel and fast approach for quantification and characterization of both exosomes and microvesicles isolated from cell culture media as well as from more complex human samples (ascites of ovarian cancer patients suitable for multiuser labs by using a flow cytometer especially designed for small particles, which can be used without adjustments prior to data acquisition. EVs can be fluorescently labeled with protein-(Carboxyfluoresceinsuccinimidyl ester, CFSE and/or lipid- (FM specific dyes, without the necessity of removing the unbound fluorescent dye by UC, which further facilitates and speeds up the characterization of microvesicles and exosomes using flow cytometry. In addition, double labeling with protein- and lipid-specific dyes enables separation of EVs from common contaminants of EV preparations, such as protein aggregates or micelles formed by unbound lipophilic styryl dyes, thus not leading to overestimation of EV numbers. Moreover, our protocol is compatible with antibody labeling using fluorescently conjugated primary antibodies. The presented methodology opens the
Pospichalova, Vendula; Svoboda, Jan; Dave, Zankruti; Kotrbova, Anna; Kaiser, Karol; Klemova, Dobromila; Ilkovics, Ladislav; Hampl, Ales; Crha, Igor; Jandakova, Eva; Minar, Lubos; Weinberger, Vit; Bryja, Vitezslav
2015-01-01
Flow cytometry is a powerful method, which is widely used for high-throughput quantitative and qualitative analysis of cells. However, its straightforward applicability for extracellular vesicles (EVs) and mainly exosomes is hampered by several challenges, reflecting mostly the small size of these vesicles (exosomes: ~80-200 nm, microvesicles: ~200-1,000 nm), their polydispersity, and low refractive index. The current best and most widely used protocol for beads-free flow cytometry of exosomes uses ultracentrifugation (UC) coupled with floatation in sucrose gradient for their isolation, labeling with lipophilic dye PKH67 and antibodies, and an optimized version of commercial high-end cytometer for analysis. However, this approach requires an experienced flow cytometer operator capable of manual hardware adjustments and calibration of the cytometer. Here, we provide a novel and fast approach for quantification and characterization of both exosomes and microvesicles isolated from cell culture media as well as from more complex human samples (ascites of ovarian cancer patients) suitable for multiuser labs by using a flow cytometer especially designed for small particles, which can be used without adjustments prior to data acquisition. EVs can be fluorescently labeled with protein-(Carboxyfluoresceinsuccinimidyl ester, CFSE) and/or lipid- (FM) specific dyes, without the necessity of removing the unbound fluorescent dye by UC, which further facilitates and speeds up the characterization of microvesicles and exosomes using flow cytometry. In addition, double labeling with protein- and lipid-specific dyes enables separation of EVs from common contaminants of EV preparations, such as protein aggregates or micelles formed by unbound lipophilic styryl dyes, thus not leading to overestimation of EV numbers. Moreover, our protocol is compatible with antibody labeling using fluorescently conjugated primary antibodies. The presented methodology opens the possibility for routine
Using mixed methods to identify factors influencing patient flow.
Van Vaerenbergh, Cindy
2009-11-01
An effective method of identifying operational factors that influence patient flow can potentially lead to improvements and thus have huge benefits on the efficiency of hospital departments. This paper presents a new inductive mixed-method approach to identify operational factors that influence patient flow through an accident and emergency (A&E) department. Preliminary explorative observations were conducted, followed by semi-structured interviews with key stakeholders. A questionnaire survey of all medical, nursing, porter and clerical staff was then conducted. The observations provided factors for further exploration: skill-mix, long working hours, equipment availability, lack of orientation programmes, inefficient IT use and issues regarding communication structures. Interviewees highlighted several factors, including availability of medical supervision and senior nursing staff, nursing documentation issues, lack of morale due to overcrowding, personality differences and factors relating to the department layout. The questionnaire respondents strongly supported the importance of the previously identified factors. This paper demonstrates an effective mixed-method approach that can be replicated by other health-care managers to identify factors influencing patient flow. Further benefits include increased volume and quality of data, increased staff awareness for the influence of internal factors on patient flow and enhancing the evidence base for future decision making when prioritizing A&E projects.
A multilevel adaptive projection method for unsteady incompressible flow
Howell, Louis H.
1993-11-01
There are two main requirements for practical simulation of unsteady flow at high Reynolds number: the algorithm must accurately propagate discontinuous flow fields without excessive artificial viscosity, and it must have some adaptive capability to concentrate computational effort where it is most needed. We satisfy the first of these requirements with a second-order Godunov method similar to those used for high-speed flows with shocks, and the second with a grid-based refinement scheme which avoids some of the drawbacks associated with unstructured meshes. These two features of our algorithm place certain constraints on the projection method used to enforce incompressibility. Velocities are cell-based, leading to a Laplacian stencil for the projection which decouples adjacent grid points. We discuss features of the multigrid and multilevel iteration schemes required for solution of the resulting decoupled problem. Variable-density flows require use of a modified projection operator--we have found a multigrid method for this modified projection that successfully handles density jumps of thousands to one. Numerical results are shown for the 2D adaptive and 3D variable-density algorithms.
Intrusive Method for Uncertainty Quantification in a Multiphase Flow Solver
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.
Drag flow analysis of Oldroyd eight constant fluid
Directory of Open Access Journals (Sweden)
A.M. Siddiqui
2016-09-01
Full Text Available This article presents the steady drag flow problems. The incompressible Oldroyd eight constant fluid flow is considered between two infinite parallel plates. Three flow problems including the Couette flow, Poiseuille flow and Couette–Poiseuille flow are modeled. The source term appearing in the nonlinear differential equation for each case is simplified with the application of modified homotopy perturbation method, and thus the general solution is obtained. The validity of second order approximate analytic solutions is tested with the aid of a numerical technique. The order of accuracy has been obtained in tabular form and the graphs are presented to demonstrate the difference between the three flow regimes.
Green chemistry and the evolution of flow analysis. A review.
Melchert, Wanessa R; Reis, Boaventura F; Rocha, Fábio R P
2012-02-10
Flow analysis has achieved its majority as a well-established tool to solve analytical problems. Evolution of flow-based approaches has been analyzed by diverse points of view, including historical aspects, the commutation concept and the impact on analytical methodologies. In this overview, the evolution of flow analysis towards green analytical chemistry is demonstrated by comparing classical procedures implemented with different flow approaches. The potential to minimize reagent consumption and waste generation and the ability to implement processes unreliable in batch to replace toxic chemicals are also emphasized. Successful applications of greener approaches in flow analysis are also discussed, focusing on the last 10 years.
On the accuracy of Whitham's method. [for steady ideal gas flow past cones
Zahalak, G. I.; Myers, M. K.
1974-01-01
The steady flow of an ideal gas past a conical body is studied by the method of matched asymptotic expansions and by Whitham's method in order to assess the accuracy of the latter. It is found that while Whitham's method does not yield a correct asymptotic representation of the perturbation field to second order in regions where the flow ahead of the Mach cone of the apex is disturbed, it does correctly predict the changes of the second-order perturbation quantities across a shock (the first-order shock strength). The results of the analysis are illustrated by a special case of a flat, rectangular plate at incidence.
Zhang, Xiujie; Pan, Chuanjie; Xu, Zengyu
2016-12-01
Numerical and experimental investigation results on the magnetohydrodynamics (MHD) film flows along flat and curved bottom surfaces are summarized in this study. A simplified modeling has been developed to study the liquid metal MHD film state, which has been validated by the existing experimental results. Numerical results on how the inlet velocity (V), the chute width (W) and the inlet film thickness (d0) affect the MHD film flow state are obtained. MHD stability analysis results are also provided in this study. The results show that strong magnetic fields make the stable V decrease several times compared to the case with no magnetic field, especially small radial magnetic fields (Bn) will have a significant impact on the MHD film flow state. Based on the above numerical and MHD stability analysis results flow control methods are proposed for flat and curved MHD film flows. For curved film flow we firstly proposed a new multi-layers MHD film flow system with a solid metal mesh to get the stable MHD film flows along the curved bottom surface. Experiments on flat and curved MHD film flows are also carried out and some firstly observed results are achieved. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2014GB125003 and 2013GB114002), National Natural Science Foundation of China (No. 11105044)
Synthetic-Eddy Method for Urban Atmospheric Flow Modelling
Pavlidis, D.; Gorman, G. J.; Gomes, J. L. M. A.; Pain, C. C.; Apsimon, H.
2010-08-01
The computational fluid dynamics code Fluidity, with anisotropic mesh adaptivity, is used as a multi-scale obstacle-accommodating meteorological model. A novel method for generating realistic inlet boundary conditions based on the view of turbulence as a superposition of synthetic eddies is adopted. It is able to reproduce prescribed first-order and second-order one-point statistics and turbulence length scales. The aim is to simulate an urban boundary layer. The model is validated against two standard benchmark tests: a plane channel flow numerical simulation and a flow past a cube physical simulation. The performed large-eddy simulations are in good agreement with both reference models giving confidence that the model can be used to successfully simulate urban atmospheric flows.
Detecting Communities by Revised Max-flow Method in Networks
Institute of Scientific and Technical Information of China (English)
LIU Chuan-Jian; ZHU Zhi-Qiang; WU Jian-Liang
2013-01-01
A ubiquitous phenomenon in networks is the presence of communities within which the network connections are dense and between which they are sparser.This paper proposes a max-flow algorithm in bipartite networks to detect communities in general networks.Firstly,we construct a bipartite network in accordance with a general network and derive a revised max-flow problem in order to uncover the community structure.Then we present a local heuristic algorithm to find the optimal solution of the revised max-flow problem.This method is applied to a variety of real-world and artificial complex networks,and the partition results confirm its effectiveness and accuracy.
Double MRT thermal lattice Boltzmann method for simulating convective flows
Energy Technology Data Exchange (ETDEWEB)
Mezrhab, Ahmed, E-mail: mezrhab@fso.ump.m [Laboratoire de Mecanique and Energetique, Departement de Physique, Faculte des Sciences, Universite Mohammed 1er, 60000 Oujda (Morocco); Amine Moussaoui, Mohammed; Jami, Mohammed [Laboratoire de Mecanique and Energetique, Departement de Physique, Faculte des Sciences, Universite Mohammed 1er, 60000 Oujda (Morocco); Naji, Hassan [Universite Lille Nord de France, F-59000 Lille, and LML UMR CNRS 8107, F-59655 Villeneuve d' Ascq cedex (France); Bouzidi, M' hamed [Universite Clermont 2, LaMI EA 3867, IUT de Montlucon, Av. A. Briand, BP 2235, F-03101 Montlucon cedex (France)
2010-07-26
A two-dimensional double Multiple Relaxation Time-Thermal Lattice Boltzmann Equation (2-MRT-TLBE) method is developed for predicting convective flows in a square differentially heated cavity filled with air (Pr=0.71). In this Letter, we propose a numerical scheme to solve the flow and the temperature fields using the MRT-D2Q9 model and the MRT-D2Q5 model, respectively. Thus, the main objective of this study is to show the effectiveness of such model to predict thermodynamics for heat transfer. This model is validated by the numerical simulations of the 2-D convective square cavity flow. Excellent agreements are obtained between numerical predictions. These results demonstrate the accuracy and the effectiveness of the proposed methodology.
Discrete Element Method Simulations for Complex Granular Flows
Guo, Yu; Curtis, Jennifer Sinclair
2015-01-01
This review article focuses on the modeling of complex granular flows employing the discrete element method (DEM) approach. The specific topic discussed is the application of DEM models for the study of the flow behavior of nonspherical, flexible, or cohesive particles, including particle breakage. The major sources of particle cohesion—liquid induced, electrostatics, van der Waals forces—and their implementation into DEM simulations are covered. These aspects of particle flow are of great importance in practical applications and hence are the significant foci of research at the forefront of current DEM modeling efforts. For example, DEM simulations of nonspherical grains can provide particle stress information needed to develop constitutive models for continuum-based simulations of large-scale industrial processes.
Ground Fault Line Selection with Improved Residual Flow Incremental Method
Directory of Open Access Journals (Sweden)
Wenhong Li
2013-08-01
Full Text Available According to the shortcoming of single-phase ground fault line selection method in the resonant grounded system such as the uncertainty of its device by fast compensation with the automatic compensation equipment, an arc suppression and residual flow incremental method is proposed to effectively choose the earth fault line. Firstly, when the single-phase ground fault occurs, the arc suppression coil parameters are adjusted to realize compensation and arc suppression. Then the arc suppression coil inductance values are modulated to make the zero-sequence current of fault line changed, at the same time, the zero-sequence current value is detected and its change will be captured to select the fault line. The simulation experiments prove that the arc grounding over voltage damage can be effectively reduced by arc suppression coil full compensation and fault line can be effectively selected by arc suppression and residual flow increment method.
Two Dimensional Lattice Boltzmann Method for Cavity Flow Simulation
Directory of Open Access Journals (Sweden)
Panjit MUSIK
2004-01-01
Full Text Available This paper presents a simulation of incompressible viscous flow within a two-dimensional square cavity. The objective is to develop a method originated from Lattice Gas (cellular Automata (LGA, which utilises discrete lattice as well as discrete time and can be parallelised easily. Lattice Boltzmann Method (LBM, known as discrete Lattice kinetics which provide an alternative for solving the Navier–Stokes equations and are generally used for fluid simulation, is chosen for the study. A specific two-dimensional nine-velocity square Lattice model (D2Q9 Model is used in the simulation with the velocity at the top of the cavity kept fixed. LBM is an efficient method for reproducing the dynamics of cavity flow and the results which are comparable to those of previous work.
Quantitative analysis of uncertainty from pebble flow in HTR
Energy Technology Data Exchange (ETDEWEB)
Chen, Hao, E-mail: haochen.heu@163.com [Fundamental Science on Nuclear Safety and Simulation Technology Laboratory, College of Nuclear Science and Technology, Harbin Engineering University, Harbin (China); Institute of Nuclear and New Energy Technology (INET), Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing (China); Fu, Li; Jiong, Guo; Ximing, Sun; Lidong, Wang [Institute of Nuclear and New Energy Technology (INET), Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing (China)
2015-12-15
Highlights: • An uncertainty and sensitivity analysis model for pebble flow has been built. • Experiment and random walk theory are used to identify uncertainty of pebble flow. • Effects of pebble flow to the core parameters are identified by sensitivity analysis. • Uncertainty of core parameters due to pebble flow is quantified for the first time. - Abstract: In pebble bed HTR, along the deterministic average flow lines, randomness exists in the flow of pebbles, which is not possible to simulate with the current reactor design codes for HTR, such as VSOP, due to the limitation of current computer capability. In order to study how the randomness of pebble flow will affect the key parameters in HTR, a new pebble flow model was set up, which has been successfully transplanted into the VSOP code. In the new pebble flow model, mixing coefficients were introduced into the fixed flow line to simulate the randomness of pebble flow. Numerical simulation and pebble flow experiments were facilitated to determine the mixing coefficients. Sensitivity analysis was conducted to achieve the conclusion that the key parameters of pebble bed HTR are not sensitive to the randomness in pebble flow. The uncertainty of maximum power density and power distribution caused by the randomness in pebble flow is very small, especially for the “multi-pass” scheme of fuel circulation adopted in the pebble bed HTR.
Technical discussions II - Flow cytometric analysis
Cunningham, A; Cid, A; Buma, AGJ
1996-01-01
In this paper the potencial of flow cytometry as applied to the aquatic life sciences is discussed. The use of flow cytometry for studying the ecotoxicology of phytoplankton was introduced. On the other hand, the new flow cytometer EUROPA was presented. This is a multilaser machine which has been sp
Technical discussions II - Flow cytometric analysis
Cunningham, A; Cid, A; Buma, AGJ
1996-01-01
In this paper the potencial of flow cytometry as applied to the aquatic life sciences is discussed. The use of flow cytometry for studying the ecotoxicology of phytoplankton was introduced. On the other hand, the new flow cytometer EUROPA was presented. This is a multilaser machine which has been sp
Theoretical analysis of tsunami generation by pyroclastic flows
Watts, P.; Waythomas, C.F.
2003-01-01
Pyroclastic flows are a common product of explosive volcanism and have the potential to initiate tsunamis whenever thick, dense flows encounter bodies of water. We evaluate the process of tsunami generation by pyroclastic flow by decomposing the pyroclastic flow into two components, the dense underflow portion, which we term the pyroclastic debris flow, and the plume, which includes the surge and coignimbrite ash cloud parts of the flow. We consider five possible wave generation mechanisms. These mechanisms consist of steam explosion, pyroclastic debris flow, plume pressure, plume shear, and pressure impulse wave generation. Our theoretical analysis of tsunami generation by these mechanisms provides an estimate of tsunami features such as a characteristic wave amplitude and wavelength. We find that in most situations, tsunami generation is dominated by the pyroclastic debris flow component of a pyroclastic flow. This work presents information sufficient to construct tsunami sources for an arbitrary pyroclastic flow interacting with most bodies of water. Copyright 2003 by the American Geophysical Union.
Probabilistic methods for rotordynamics analysis
Wu, Y.-T.; Torng, T. Y.; Millwater, H. R.; Fossum, A. F.; Rheinfurth, M. H.
1991-01-01
This paper summarizes the development of the methods and a computer program to compute the probability of instability of dynamic systems that can be represented by a system of second-order ordinary linear differential equations. Two instability criteria based upon the eigenvalues or Routh-Hurwitz test functions are investigated. Computational methods based on a fast probability integration concept and an efficient adaptive importance sampling method are proposed to perform efficient probabilistic analysis. A numerical example is provided to demonstrate the methods.
Review of Upscaling Methods for Describing Unsaturated Flow
Energy Technology Data Exchange (ETDEWEB)
BD Wood
2000-09-26
The representation of small-scale features can be a challenge when attempting to model unsaturated flow in large domains. Upscaling methods offer the possibility of reducing the amount of resolution required to adequately simulate such a problem. In this report, the various upscaling techniques that are discussed in the literature are reviewed. The following upscaling methods have been identified from the literature: (1) stochastic methods, (2) renormalization methods, and (3) volume averaging and homogenization methods; in addition, a final technique, full resolution numerical modeling, is also discussed. Each of these techniques has its advantages and disadvantages. The trade-off is a reduction in accuracy in favor of a method that is easier to employ. For practical applications, the most reasonable approach appears to be one in which any of the upscaling methods identified above maybe suitable for upscaling in regions where the variations in the parameter fields are small. For regions where the subsurface structure is more complex, only the homogenization and volume averaging methods are probably suitable. With the continual increases in computational capacity, fill-resolution numerical modeling may in many instances provide a tractable means of solving the flow problem in unsaturated systems.
A variational multiscale method for particle-cloud tracking in turbomachinery flows
Corsini, A.; Rispoli, F.; Sheard, A. G.; Takizawa, K.; Tezduyar, T. E.; Venturini, P.
2014-11-01
We present a computational method for simulation of particle-laden flows in turbomachinery. The method is based on a stabilized finite element fluid mechanics formulation and a finite element particle-cloud tracking method. We focus on induced-draft fans used in process industries to extract exhaust gases in the form of a two-phase fluid with a dispersed solid phase. The particle-laden flow causes material wear on the fan blades, degrading their aerodynamic performance, and therefore accurate simulation of the flow would be essential in reliable computational turbomachinery analysis and design. The turbulent-flow nature of the problem is dealt with a Reynolds-Averaged Navier-Stokes model and Streamline-Upwind/Petrov-Galerkin/Pressure-Stabilizing/Petrov-Galerkin stabilization, the particle-cloud trajectories are calculated based on the flow field and closure models for the turbulence-particle interaction, and one-way dependence is assumed between the flow field and particle dynamics. We propose a closure model utilizing the scale separation feature of the variational multiscale method, and compare that to the closure utilizing the eddy viscosity model. We present computations for axial- and centrifugal-fan configurations, and compare the computed data to those obtained from experiments, analytical approaches, and other computational methods.
OPR1000 RCP Flow Coastdown Analysis using SPACE Code
Energy Technology Data Exchange (ETDEWEB)
Lee, Dong-Hyuk; Kim, Seyun [KHNP CRI, Daejeon (Korea, Republic of)
2016-10-15
The Korean nuclear industry developed a thermal-hydraulic analysis code for the safety analysis of PWRs, named SPACE(Safety and Performance Analysis Code for Nuclear Power Plant). Current loss of flow transient analysis of OPR1000 uses COAST code to calculate transient RCS(Reactor Coolant System) flow. The COAST code calculates RCS loop flow using pump performance curves and RCP(Reactor Coolant Pump) inertia. In this paper, SPACE code is used to reproduce RCS flowrates calculated by COAST code. The loss of flow transient is transient initiated by reduction of forced reactor coolant circulation. Typical loss of flow transients are complete loss of flow(CLOF) and locked rotor(LR). OPR1000 RCP flow coastdown analysis was performed using SPACE using simplified nodalization. Complete loss of flow(4 RCP trip) was analyzed. The results show good agreement with those from COAST code, which is CE code for calculating RCS flow during loss of flow transients. Through this study, we confirmed that SPACE code can be used instead of COAST code for RCP flow coastdown analysis.
A Calculus for Control Flow Analysis of Security Protocols
DEFF Research Database (Denmark)
Buchholtz, Mikael; Nielson, Hanne Riis; Nielson, Flemming
2004-01-01
analysis methodology. We pursue an analysis methodology based on control flow analysis in flow logic style and we have previously shown its ability to analyse a variety of security protocols. This paper develops a calculus, LysaNS that allows for much greater control and clarity in the description...
A Coupling Simulation Between Soil Scour and Seepage Flow by Using a Stabilized ISPH Method
Directory of Open Access Journals (Sweden)
Nogami Tomotaka
2016-01-01
Full Text Available In 2011, the example that breakwaters collapsed because of the basic ground’s destabilization was reported by Tohoku-Kanto earthquake tsunami. Fluid-Structure-Soil coupling simulation is desired for a systematic comprehension of the breakwater collapse mechanism, and it may help to develop next disaster prevention method. In this study, A particle simulation tool based on the SPH has been modified and improved to analyze seepage flow and soil scouring. In seepage flow analysis, as a first step, this simulation treat the surface flow and seepage flow interactions by using governing equation. In the scouring analysis, soil scour is judged by an empirical criteria based on quicksand quantity formula.
A fictitious domain method for particulate flows with heat transfer
Yu, Zhaosheng; Shao, Xueming; Wachs, Anthony
2006-09-01
The distributed-Lagrange-multiplier/fictitious-domain (DLM/FD) method of Glowinski et al. [R. Glowinski, T.-W. Pan, T.I. Hesla, D.D. Joseph, A distributed Lagrange multiplier/fictitious domain method for particulate flows, Int. J. Multiphase Flow 25 (1999) 755-794] is extended to deal with heat transfer in particulate flows in two dimensions. The Boussinesq approximation is employed for the coupling between the flow and temperature fields. The fluid-flow equations are solved with the finite-difference projection method on a half-staggered grid. In our operator splitting scheme, the Lagrange multipliers at the previous time level are kept in the fluid equations, and the new Lagrange multipliers for the rigid-body motion constraint and the Dirichlet temperature boundary condition are determined from the reduced saddle-point problem, whereas a very simple scheme based on the fully explicit computation of the Lagrange multiplier is proposed for the problem in which the solid heat conduction inside the particle boundary is also considered. Our code for the case of fixed temperature on the immersed boundary is verified by comparing favorably our results on the natural convection driven by a hot cylinder eccentrically placed in a square box and on the sedimentation of a cold circular particle in a vertical channel to the data in the literature. The code for the case of freely varying temperature on the boundaries of freely moving particles is applied to analyze the motion of a catalyst particle in a box and in particular the heat conductivities of nanofluids and sheared non-colloidal suspensions, respectively. Our preliminary computational results support the argument that the micro-heat-convection in the fluids is primarily responsible for the unusually high heat conductivity of nanofluids. It is shown that the Peclet number plays a negative role in the diffusion-related heat conductivity of a sheared non-colloidal suspension, whereas the Reynolds number does the
The curvHDR method for gating flow cytometry samples
Directory of Open Access Journals (Sweden)
Wand Matthew P
2010-01-01
Full Text Available Abstract Background High-throughput flow cytometry experiments produce hundreds of large multivariate samples of cellular characteristics. These samples require specialized processing to obtain clinically meaningful measurements. A major component of this processing is a form of cell subsetting known as gating. Manual gating is time-consuming and subjective. Good automatic and semi-automatic gating algorithms are very beneficial to high-throughput flow cytometry. Results We develop a statistical procedure, named curvHDR, for automatic and semi-automatic gating. The method combines the notions of significant high negative curvature regions and highest density regions and has the ability to adapt well to human-perceived gates. The underlying principles apply to dimension of arbitrary size, although we focus on dimensions up to three. Accompanying software, compatible with contemporary flow cytometry infor-matics, is developed. Conclusion The method is seen to adapt well to nuances in the data and, to a reasonable extent, match human perception of useful gates. It offers big savings in human labour when processing high-throughput flow cytometry data whilst retaining a good degree of efficacy.
Experimental study on two-dimensional film flow with local measurement methods
Energy Technology Data Exchange (ETDEWEB)
Yang, Jin-Hwa, E-mail: evo03@snu.ac.kr [Nuclear Thermal-Hydraulic Engineering Laboratory, Seoul National University, Gwanak 599, Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Korea Atomic Energy Research Institute, 989-111, Daedeok-daero, Yuseong-gu, Daejeon 305-600 (Korea, Republic of); Cho, Hyoung-Kyu [Nuclear Thermal-Hydraulic Engineering Laboratory, Seoul National University, Gwanak 599, Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Kim, Seok [Korea Atomic Energy Research Institute, 989-111, Daedeok-daero, Yuseong-gu, Daejeon 305-600 (Korea, Republic of); Euh, Dong-Jin, E-mail: djeuh@kaeri.re.kr [Korea Atomic Energy Research Institute, 989-111, Daedeok-daero, Yuseong-gu, Daejeon 305-600 (Korea, Republic of); Park, Goon-Cherl [Nuclear Thermal-Hydraulic Engineering Laboratory, Seoul National University, Gwanak 599, Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of)
2015-12-01
Highlights: • An experimental study on the two-dimensional film flow with lateral air injection was performed. • The ultrasonic thickness gauge was used to measure the local liquid film thickness. • The depth-averaged PIV (Particle Image Velocimetry) method was applied to measure the local liquid film velocity. • The uncertainty of the depth-averaged PIV was quantified with a validation experiment. • Characteristics of two-dimensional film flow were classified following the four different flow patterns. - Abstract: In an accident condition of a nuclear reactor, multidimensional two-phase flows may occur in the reactor vessel downcomer and reactor core. Therefore, those have been regarded as important issues for an advanced thermal-hydraulic safety analysis. In particular, the multi-dimensional two-phase flow in the upper downcomer during the reflood phase of large break loss of coolant accident appears with an interaction between a downward liquid and a transverse gas flow, which determines the bypass flow rate of the emergency core coolant and subsequently, the reflood coolant flow rate. At present, some thermal-hydraulic analysis codes incorporate multidimensional modules for the nuclear reactor safety analysis. However, their prediction capability for the two-phase cross flow in the upper downcomer has not been validated sufficiently against experimental data based on local measurements. For this reason, an experimental study was carried out for the two-phase cross flow to clarify the hydraulic phenomenon and provide local measurement data for the validation of the computational tools. The experiment was performed in a 1/10 scale unfolded downcomer of Advanced Power Reactor 1400 (APR1400). Pitot tubes, a depth-averaged PIV method and ultrasonic thickness gauge were applied for local measurement of the air velocity, the liquid film velocity and the liquid film thickness, respectively. The uncertainty of the depth-averaged PIV method for the averaged
Nonlinear programming analysis and methods
Avriel, Mordecai
2012-01-01
This text provides an excellent bridge between principal theories and concepts and their practical implementation. Topics include convex programming, duality, generalized convexity, analysis of selected nonlinear programs, techniques for numerical solutions, and unconstrained optimization methods.
The New Performance Calculation Method of Fouled Axial Flow Compressor
Directory of Open Access Journals (Sweden)
Huadong Yang
2014-01-01
Full Text Available Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section includes the first 50% stages which reflect the fouling level, and the second section includes the last 50% stages which are viewed as the clean stage because of less deposits. In this model, the performance of the first section is obtained by combining scaling law method and linear progression model with traditional stage stacking method; simultaneously ambient conditions and engine configurations are considered. On the other hand, the performance of the second section is calculated by averaged infinitesimal stage method which is based on Reynolds’ law of similarity. Finally, the model is successfully applied to predict the 8-stage axial flow compressor and 16-stage LM2500-30 compressor. The change of thermodynamic parameters such as pressure ratio, efficiency with the operating time, and stage number is analyzed in detail.
The new performance calculation method of fouled axial flow compressor.
Yang, Huadong; Xu, Hong
2014-01-01
Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section includes the first 50% stages which reflect the fouling level, and the second section includes the last 50% stages which are viewed as the clean stage because of less deposits. In this model, the performance of the first section is obtained by combining scaling law method and linear progression model with traditional stage stacking method; simultaneously ambient conditions and engine configurations are considered. On the other hand, the performance of the second section is calculated by averaged infinitesimal stage method which is based on Reynolds' law of similarity. Finally, the model is successfully applied to predict the 8-stage axial flow compressor and 16-stage LM2500-30 compressor. The change of thermodynamic parameters such as pressure ratio, efficiency with the operating time, and stage number is analyzed in detail.
New pressure transient analysis methods for naturally fractured reservoirs
Energy Technology Data Exchange (ETDEWEB)
Serra, K.; Raghavan, R.; Reynolds, A.C.
1983-10-01
This paper presents new methods for analyzing pressure drawdown and buildup data obtained at wells producing naturally fractured reservoirs. The model used in this study assumes unsteady-state fluid transfer from the matrix system to the fracture system. A new flow regime is identified. The discovery of this flow regime explains field behavior that has been considered unusual. The probability of obtaining data reflecting this flow regime in a field test is higher than that of obtaining the classical responses given in the literature. The identification of this new flow regime provides methods for preparing a complete analysis of pressure data obtained from naturally fractured reservoirs. Applications to field data are discussed.
New pressure transient analysis methods for naturally fractured reservoirs
Energy Technology Data Exchange (ETDEWEB)
Serra, K.; Raghavan, R.; Reynolds, A.C.
1983-12-01
This paper presents new methods for analyzing pressure drawdown and buildup data obtained at wells producing naturally fractured reservoirs. The model used in this study assumes unsteady-state fluid transfer from the matrix system to the fracture system. A new flow regime is identified. The discovery of this flow regime explains field behavior that has been considered unusual. The probability of obtaining data reflecting this flow regime in a field test is higher than that of obtaining the classical responses given in the literature. The identification of this new flow regime provides methods for preparing a complete analysis of pressure data obtained from naturally fractured reservoirs. Applications to field data are discussed.
Digital analysis and sorting of fluorescence lifetime by flow cytometry.
Houston, Jessica P; Naivar, Mark A; Freyer, James P
2010-09-01
Frequency-domain flow cytometry techniques are combined with modifications to the digital signal-processing capabilities of the open reconfigurable cytometric acquisition system (ORCAS) to analyze fluorescence decay lifetimes and control sorting. Real-time fluorescence lifetime analysis is accomplished by rapidly digitizing correlated, radiofrequency (RF)-modulated detector signals, implementing Fourier analysis programming with ORCAS' digital signal processor (DSP) and converting the processed data into standard cytometric list mode data. To systematically test the capabilities of the ORCAS 50 MS/sec analog-to-digital converter (ADC) and our DSP programming, an error analysis was performed using simulated light scatter and fluorescence waveforms (0.5-25 ns simulated lifetime), pulse widths ranging from 2 to 15 micros, and modulation frequencies from 2.5 to 16.667 MHz. The standard deviations of digitally acquired lifetime values ranged from 0.112 to >2 ns, corresponding to errors in actual phase shifts from 0.0142 degrees to 1.6 degrees. The lowest coefficients of variation (digital analysis system to a previous analog phase-sensitive flow cytometer demonstrated similar precision and accuracy on measurements of a range of fluorescent microspheres, unstained cells, and cells stained with three common fluorophores. Sorting based on fluorescence lifetime was accomplished by adding analog outputs to ORCAS and interfacing with a commercial cell sorter with a RF-modulated solid-state laser. Two populations of fluorescent microspheres with overlapping fluorescence intensities but different lifetimes (2 and 7 ns) were separated to approximately 98% purity. Overall, the digital signal acquisition and processing methods we introduce present a simple yet robust approach to phase-sensitive measurements in flow cytometry. The ability to simply and inexpensively implement this system on a commercial flow sorter will allow both better dissemination of this technology and better
Analytical methods for heat transfer and fluid flow problems
Weigand, Bernhard
2015-01-01
This book describes useful analytical methods by applying them to real-world problems rather than solving the usual over-simplified classroom problems. The book demonstrates the applicability of analytical methods even for complex problems and guides the reader to a more intuitive understanding of approaches and solutions. Although the solution of Partial Differential Equations by numerical methods is the standard practice in industries, analytical methods are still important for the critical assessment of results derived from advanced computer simulations and the improvement of the underlying numerical techniques. Literature devoted to analytical methods, however, often focuses on theoretical and mathematical aspects and is therefore useless to most engineers. Analytical Methods for Heat Transfer and Fluid Flow Problems addresses engineers and engineering students. The second edition has been updated, the chapters on non-linear problems and on axial heat conduction problems were extended. And worked out exam...
SIGNAL FLOW GRAPH ANALYSIS OF MECHANICAL ENGINEERING SYSTEMS
CONTROL SYSTEMS, *MECHANICS, *STRUCTURES, *THERMODYNAMICS, *TOPOLOGY, BEAMS(ELECTROMAGNETIC), BEAMS(STRUCTURAL), GAS FLOW, GEARS, HEAT EXCHANGERS, MATHEMATICAL ANALYSIS, MATHEMATICS, MECHANICAL ENGINEERING , RAMJET ENGINES.
Axial flow heat exchanger devices and methods for heat transfer using axial flow devices
Energy Technology Data Exchange (ETDEWEB)
Koplow, Jeffrey P.
2016-02-16
Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.
Aerosol flow reactor method for synthesis of drug nanoparticles.
Eerikäinen, Hannele; Watanabe, Wiwik; Kauppinen, Esko I; Ahonen, P Petri
2003-05-01
An aerosol flow reactor method, a one-step continuous process to produce nanometer-sized drug particles with unimodal size distribution, was developed. This method involves first dissolving the drug material in question into a suitable solvent, which is then followed by atomising the solution as fine droplets into carrier gas. A heated laminar flow reactor tube is used to evaporate the solvent, and solid drug nanoparticles are formed. In this study, the effect of drying temperature on the particle size and morphology was examined. A glucocorticosteroid used for asthma therapy, beclomethasone dipropionate, was selected as an experimental model drug. The geometric number mean particle diameter increases significantly with increasing reactor temperatures due to formation of hollow nanoparticles. Above 160 degrees C, however, further increase in temperature results in decreasing particle size. The produced nanoparticles are spherical and show smooth surfaces at all studied experimental conditions.
Analysis of system trustworthiness based on information flow noninterference theory
Institute of Scientific and Technical Information of China (English)
Xiangying Kong; Yanhui Chen; Yi Zhuang
2015-01-01
The trustworthiness analysis and evaluation are the bases of the trust chain transfer. In this paper the formal method of trustworthiness analysis of a system based on the noninterfer-ence (NI) theory of the information flow is studied. Firstly, existing methods cannot analyze the impact of the system states on the trustworthiness of software during the process of trust chain trans-fer. To solve this problem, the impact of the system state on trust-worthiness of software is investigated, the run-time mutual interfer-ence behavior of software entities is described and an interference model of the access control automaton of a system is established. Secondly, based on the intransitive noninterference (INI) theory, a formal analytic method of trustworthiness for trust chain transfer is proposed, providing a theoretical basis for the analysis of dynamic trustworthiness of software during the trust chain transfer process. Thirdly, a prototype system with dynamic trustworthiness on a plat-form with dual core architecture is constructed and a verification algorithm of the system trustworthiness is provided. Final y, the monitor hypothesis is extended to the dynamic monitor hypothe-sis, a theorem of static judgment rule of system trustworthiness is provided, which is useful to prove dynamic trustworthiness of a system at the beginning of system construction. Compared with previous work in this field, this research proposes not only a formal analytic method for the determination of system trustworthiness, but also a modeling method and an analysis algorithm that are feasible for practical implementation.
A high-throughput method for detection of DNA in chloroplasts using flow cytometry
Directory of Open Access Journals (Sweden)
Oldenburg Delene J
2007-03-01
Full Text Available Abstract Background The amount of DNA in the chloroplasts of some plant species has been shown recently to decline dramatically during leaf development. A high-throughput method of DNA detection in chloroplasts is now needed in order to facilitate the further investigation of this process using large numbers of tissue samples. Results The DNA-binding fluorophores 4',6-diamidino-2-phenylindole (DAPI, SYBR Green I (SG, SYTO 42, and SYTO 45 were assessed for their utility in flow cytometric analysis of DNA in Arabidopsis chloroplasts. Fluorescence microscopy and real-time quantitative PCR (qPCR were used to validate flow cytometry data. We found neither DAPI nor SYTO 45 suitable for flow cytometric analysis of chloroplast DNA (cpDNA content, but did find changes in cpDNA content during development by flow cytometry using SG and SYTO 42. The latter dye provided more sensitive detection, and the results were similar to those from the fluorescence microscopic analysis. Differences in SYTO 42 fluorescence were found to correlate with differences in cpDNA content as determined by qPCR using three primer sets widely spaced across the chloroplast genome, suggesting that the whole genome undergoes copy number reduction during development, rather than selective reduction/degradation of subgenomic regions. Conclusion Flow cytometric analysis of chloroplasts stained with SYTO 42 is a high-throughput method suitable for determining changes in cpDNA content during development and for sorting chloroplasts on the basis of DNA content.
Directory of Open Access Journals (Sweden)
Adesina, L.M
2015-07-01
Full Text Available The solution to power flow is one of the most important problems in electrical power systems. Traditional methods have been previously used for power flow analysis, but with prevalent drawbacks such as abnormal operating solutions and divergences in heavy loads. This paper presents power flow analysis in a power system, by modelling a typical 33kV Distribution Network, and simulating using the NEPLAN software for power flow studies. Island Business Unit’s (IBU 33kV network of Eko Electricity Distribution Plc (EKEDP for a scenario day is taken as case study in the analysis. The most important parameters of power flow analysis is utilized to find the magnitude and phase angles of the voltages at each Busbar, as well as the real and reactive power flowing through each distribution line within the network under consideration.
Analysis of the stability and density waves for traffic flow
Institute of Scientific and Technical Information of China (English)
薛郁
2002-01-01
In this paper, the optimal velocity model of traffic is extended to take into account the relative velocity. Thestability and density waves for traffic flow are investigated analytically with the perturbation method. The stabilitycriterion is derived by the linear stability analysis. It is shown that the triangular shock wave, soliton wave and kinkwave appear respectively in our model for density waves in the three regions: stable, metastable and unstable regions.These correspond to the solutions of the Burgers equation, Kortewegg-de Vries equation and modified Korteweg-de Vriesequation.The analytical results are confirmed to be in good agreement with those of numerical simulation. All theresults indicate that the interaction of a car with relative velocity can affect the stability of the traffic flow and raisecritical density.
Analysis od Ducted Propellers in Steady Flow
1986-02-01
P - ..-- ~ - ....- . *.* .*-.... *% * . N 1-.- TABLE OF CONTENTS 1. BACKGROUND. 1 2. VISCOUS EFFECTS IN TIP GAP FLOWS . 4 3. LIFTING LINE...the development of PSF and BPSF, for which the reader is referred to the beforementioned publications. 6 *-3- 2. VISCOUS EFFECTS IN TIP GAP FLOWS One...these considerations still apply. The existance of such a boundary layer is certainly due to viscous effects, but the local gap flow will be primarily
A Simple Method of FLow Field DIagnosis in Multistage Axial Flow Compressors
Institute of Scientific and Technical Information of China (English)
JieLiu; DajunYe
1994-01-01
The calculating method of flow field diagnosis in multistage axial compressors is presented in this paper.The distributions of loss and deviation angle of every blade row,and blockage factors are evalusted using tested total temperature and total pressure at inlet and outlet of compressor,as well as the endwall static pressures.One operating Mode of a two-stage fan is presented comparing results from the diagnostic method with measurements,and the results have demonstrated the important effects of diagnostic method.
Bayesian Methods for Statistical Analysis
Puza, Borek
2015-01-01
Bayesian methods for statistical analysis is a book on statistical methods for analysing a wide variety of data. The book consists of 12 chapters, starting with basic concepts and covering numerous topics, including Bayesian estimation, decision theory, prediction, hypothesis testing, hierarchical models, Markov chain Monte Carlo methods, finite population inference, biased sampling and nonignorable nonresponse. The book contains many exercises, all with worked solutions, including complete c...
Institute of Scientific and Technical Information of China (English)
He Zhi-guo; Mao Gen-hai; Yuan Xing-ming
2003-01-01
The 3-D turbulent flows in a valve pipe were described by the incompressible Reynolds-averaged Navier-Stokes equations with an RNG k-ε turbulence model. With the finite volume method and a body-fitted coordinate system, the discretised equations were solved by the SIMPLEST algorithm. The numerical result of a cut-off valve with curved inlet shows the flow characteristics and the main cause of energy loss when fluid flows through a valve. And then, the boundaries of valve were modified in order to reduce the energy loss. The computational results of modified valve show that the numerical value of turbulent kinetic energy is lower, and that the modified design of the 3-D valve boundaries is much better. The analysis of the result also shows that RNG k-ε turbulence model can successfully be used to predict the 3-D turbulent separated flows and the secondary flow inside valve pipes.
Design of Poiseuille Flow Controllers Using the Method of Inequalities
Institute of Scientific and Technical Information of China (English)
John McKernan; James F.Whidborne; George Papadakis
2009-01-01
This paper investigates the use of the method of inequalities (MoI) to design output-feedback compensators for the problem of the control of instabilities in a laminar plane Poiseuille flow.In common with many flows,the dynamics of streamwise vortices in plane Poiseuille flow are very non-normal.Consequently,small perturbations grow rapidly with a large transient that may trigger nonlinearities and lead to turbulence even though such perturbations would,in a linear flow model,eventually decay.Such a system can be described as a conditionally linear system.The sensitivity is measured using the maximum transient energy growth,which is widely used in the fluid dynamics community.The paper considers two approaches.In the first approach,the MoI is used to design low-order proportional and proportional-integral (PI) controllers.In the second one,the MoI is combined with McFarlane and Glover's H∞ loop-shaping design procedure in a mixed-optimization approach.
Determination of uranium and zirconium by flow injection analysis
Energy Technology Data Exchange (ETDEWEB)
Sousa, Alvaro S.F. de; Domingues, Maria de L.F.; Rocha, Valeska P. de Araujo; Jesus, Camila S. de, E-mail: alvaro@ien.gov.br, E-mail: valeska@ien.gov.br, E-mail: luma@ien.gov.br, E-mail: camilasaj@gmail.com [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)
2013-07-01
As an integral part of chemical quality control of nuclear materials a method for determination of uranium and zirconium, in a mixture is presented. A simple, cheap, selective and quantitative Flow Injection Analysis (FIA) system was developed. Zirconium and uranium were determinate in presence of each other and no prior separation was needed. Arsenazo III was used as a colorimetric reagent and parameters such as acidity and reagents concentration were studied and optimized. An analytical throughput of 30 sample determination per hour was obtained. (author)
Numerical Method for Darcy Flow Derived Using Discrete Exterior Calculus
Hirani, A. N.; Nakshatrala, K. B.; Chaudhry, J. H.
2015-05-01
We derive a numerical method for Darcy flow, and also for Poisson's equation in mixed (first order) form, based on discrete exterior calculus (DEC). Exterior calculus is a generalization of vector calculus to smooth manifolds and DEC is one of its discretizations on simplicial complexes such as triangle and tetrahedral meshes. DEC is a coordinate invariant discretization, in that it does not depend on the embedding of the simplices or the whole mesh. We start by rewriting the governing equations of Darcy flow using the language of exterior calculus. This yields a formulation in terms of flux differential form and pressure. The numerical method is then derived by using the framework provided by DEC for discretizing differential forms and operators that act on forms. We also develop a discretization for a spatially dependent Hodge star that varies with the permeability of the medium. This also allows us to address discontinuous permeability. The matrix representation for our discrete non-homogeneous Hodge star is diagonal, with positive diagonal entries. The resulting linear system of equations for flux and pressure are saddle type, with a diagonal matrix as the top left block. The performance of the proposed numerical method is illustrated on many standard test problems. These include patch tests in two and three dimensions, comparison with analytically known solutions in two dimensions, layered medium with alternating permeability values, and a test with a change in permeability along the flow direction. We also show numerical evidence of convergence of the flux and the pressure. A convergence experiment is included for Darcy flow on a surface. A short introduction to the relevant parts of smooth and discrete exterior calculus is included in this article. We also include a discussion of the boundary condition in terms of exterior calculus.
Danad, Ibrahim; Szymonifka, Jackie; Twisk, Jos W.R.; Norgaard, Bjarne L.; Zarins, Christopher K.; Knaapen, Paul
2017-01-01
Aims The aim of this study was to determine the diagnostic performance of single-photon emission computed tomography (SPECT), stress echocardiography (SE), invasive coronary angiography (ICA), coronary computed tomography angiography (CCTA), fractional flow reserve (FFR) derived from CCTA (FFRCT), and cardiac magnetic resonance (MRI) imaging when directly compared with an FFR reference standard. Method and results PubMed and Web of Knowledge were searched for investigations published between 1 January 2002 and 28 February 2015. Studies performing FFR in at least 75% of coronary vessels for the diagnosis of ischaemic coronary artery disease (CAD) were included. Twenty-three articles reporting on 3788 patients and 5323 vessels were identified. Meta-analysis was performed for pooled sensitivity, specificity, likelihood ratios (LR), diagnostic odds ratio, and summary receiver operating characteristic curves. In contrast to ICA, CCTA, and FFRCT reports, studies evaluating SPECT, SE, and MRI were largely retrospective, single-centre and with generally smaller study samples. On a per-patient basis, the sensitivity of CCTA (90%, 95% CI: 86–93), FFRCT (90%, 95% CI: 85–93), and MRI (90%, 95% CI: 75–97) were higher than for SPECT (70%, 95% CI: 59–80), SE (77%, 95% CI: 61–88), and ICA (69%, 95% CI: 65–75). The highest and lowest per-patient specificity was observed for MRI (94%, 95% CI: 79–99) and for CCTA (39%, 95% CI: 34–44), respectively. Similar specificities were noted for SPECT (78%, 95% CI: 68–87), SE (75%, 95% CI: 63–85), FFRCT (71%, 95% CI: 65–75%), and ICA (67%, 95% CI: 63–71). On a per-vessel basis, the highest sensitivity was for CCTA (pooled sensitivity, 91%: 88–93), MRI (91%: 84–95), and FFRCT (83%, 78–87), with lower sensitivities for ICA (71%, 69–74), and SPECT (57%: 49–64). Per-vessel specificity was highest for MRI (85%, 79–89), FFRCT (78%: 78–81), and SPECT (75%: 69–80), whereas ICA (66%: 64–68) and CCTA (58%: 55
Institute of Scientific and Technical Information of China (English)
李剑慧; 臧斌宇; 吴蓉; 朱传琪
2002-01-01
Parallelizing compilers have made great progress in recent years. However, there still remains a gap between the current ability of parallelizing compilers and their final goals.In order to achieve the maximum parallelism, run-time techniques were used in parallelizing compilers during last few years. First, this paper presents a basic run-time privatization method.The definition of run-time dead code is given and its side effect is discussed. To eliminate the imprecision caused by the run-time dead code, backward data-flow information must be used.Proteus Test, which can use backward information in run-time, is then presented to exploit more dynamic parallelism. Also, a variation of Proteus Test, the Advanced Proteus Test, is offered to achieve partial parallelism. Proteus Test was implemented on the parallelizing compiler AFT.In the end of this paper the program fpppp.f of Spec95fp Benchmark is taken as an example, to show the effectiveness of Proteus Test.
Sulfur Flow Analysis for New Generation Steel Manufacturing Process
Institute of Scientific and Technical Information of China (English)
HU Chang-qing; ZHANG Chun-xia; HAN Xiao-wei; YIN Rui-yu
2008-01-01
Sulfur flow for new generation steel manufacturing process is analyzed by the method of material flow analysis,and measures for SO2 emission reduction are put forward as assessment and target intervention of the results.The results of sulfur flow analysis indicate that 90% of sulfur comes from fuels.Sulfur finally discharges from the steel manufacturing route in various steps,and the main point is BF and BOF slag desulfurization.In sintering process,the sulfur is removed by gasification,and sintering process is the main source of SO2 emission.The sulfur content of coke oven gas (COG) is an important factor affecting SO2 emission.Therefore,SO2 emission reduction should be started from the optimization and integration of steel manufacturing route,sulfur burden should be reduced through energy saving and consumption reduction,and the sulfur content of fuel should be controlled.At the same time,BF and BOF slag desulfurization should be optimized further and coke oven gas and sintering exhausted gas desulfurization should be adopted for SO2 emission reduction and reuse of resource,to achieve harmonic coordination of economic,social,and environmental effects for sustainable development.
POD- Mapping and analysis of hydroturbine exit flow dynamics
Kjeldsen, Morten; Finstad, Pal Henrik
2012-11-01
Pairwise radial dynamic measurements of the swirling draft tube flow have been made at the 25 MW Svorka power plant in Surnadal operating at 48% load at 6 radial and 7 angular positions. The data is analyzed with traditional methods as well as with POD. The measurements were made in the turbine draft tube/exit flow in an axial measurement plane about 1200mm downstream the turbine runner. The draft tube diameter in the measurement plane is about 1300mm. The flow rate during measurements was close to 5.8m3/s. Two probes were used; both of length Le=700 mm and made of stainless steel with an outer diameter of Do=20 mm and inner diameter Di=4mm. At the end of each probe a full bridge cylindrical KULITE xcl152, 0-3.5, was mounted. 90 seconds samples at 10 kS/s were taken. The POD analysis largely follows that of Tutkun et al. (see e.g. AIAA J., 45,5,2008). The analysis shows that 26% of the pressure pulsation energy can be addressed to azimuthal mode 1. The work has been supported by Energy Norway.
A New Void Fraction Measurement Method for Gas-Liquid Two-Phase Flow in Small Channels.
Li, Huajun; Ji, Haifeng; Huang, Zhiyao; Wang, Baoliang; Li, Haiqing; Wu, Guohua
2016-01-27
Based on a laser diode, a 12 × 6 photodiode array sensor, and machine learning techniques, a new void fraction measurement method for gas-liquid two-phase flow in small channels is proposed. To overcome the influence of flow pattern on the void fraction measurement, the flow pattern of the two-phase flow is firstly identified by Fisher Discriminant Analysis (FDA). Then, according to the identification result, a relevant void fraction measurement model which is developed by Support Vector Machine (SVM) is selected to implement the void fraction measurement. A void fraction measurement system for the two-phase flow is developed and experiments are carried out in four different small channels. Four typical flow patterns (including bubble flow, slug flow, stratified flow and annular flow) are investigated. The experimental results show that the development of the measurement system is successful. The proposed void fraction measurement method is effective and the void fraction measurement accuracy is satisfactory. Compared with the conventional laser measurement systems using standard laser sources, the developed measurement system has the advantages of low cost and simple structure. Compared with the conventional void fraction measurement methods, the proposed method overcomes the influence of flow pattern on the void fraction measurement. This work also provides a good example of using low-cost laser diode as a competent replacement of the expensive standard laser source and hence implementing the parameter measurement of gas-liquid two-phase flow. The research results can be a useful reference for other researchers' works.
Empirical analysis of heterogeneous traffic flow
Ambarwati, L.; Pel, A.J.; Verhaeghe, R.J.; Van Arem, B.
2013-01-01
Traffic flow in many developing countries is strongly mixed comprising vehicle types, such as motorcycles, cars, (mini) buses, and trucks; furthermore, traffic flow typically exhibits free inter-lane exchanges. This phenomenon causes a complex vehicle interaction, rendering most existing traffic flo
ANALYSIS OF TRANSONIC FLOW PAST CUSPED AIRFOILS
Directory of Open Access Journals (Sweden)
Jiří Stodůlka
2015-06-01
Full Text Available Transonic flow past two cusped airfoils is numerically solved and achieved results are analyzed by means of flow behavior and oblique shocks formation.Regions around sharp trailing edges are studied in detail and parameters of shock waves are solved and compared using classical shock polar approach and verified by reduction parameters for symmetric configurations.
Flow cytometry-based DNA hybridization and polymorphism analysis
Energy Technology Data Exchange (ETDEWEB)
Cai, H.; Kommander, K.; White, P.S.; Nolan, J.P.
1998-07-01
Functional analysis of the humane genome, including the quantification of differential gene expression and the identification of polymorphic sites and disease genes, is an important element of the Human Genome Project. Current methods of analysis are mainly gel-based assays that are not well-suited to rapid genome-scale analyses. To analyze DNA sequence on a large scale, robust and high throughput assays are needed. The authors are developing a suite of microsphere-based approaches employing fluorescence detection to screen and analyze genomic sequence. The approaches include competitive DNA hybridization to measure DNA or RNA targets in unknown samples, and oligo ligation or extension assays to analyze single-nucleotide polymorphisms. Apart from the advances of sensitivity, simplicity, and low sample consumption, these flow cytometric approaches have the potential for high throughput multiplexed analysis using multicolored microspheres and automated sample handling.
Analysis of Precision of Activation Analysis Method
DEFF Research Database (Denmark)
Heydorn, Kaj; Nørgaard, K.
1973-01-01
The precision of an activation-analysis method prescribes the estimation of the precision of a single analytical result. The adequacy of these estimates to account for the observed variation between duplicate results from the analysis of different samples and materials, is tested by the statistic T......, which is shown to be approximated by a χ2 distribution. Application of this test to the results of determinations of manganese in human serum by a method of established precision, led to the detection of airborne pollution of the serum during the sampling process. The subsequent improvement in sampling...... conditions was shown to give not only increased precision, but also improved accuracy of the results....
A power flow method for evaluating vibration from underground railways
Hussein, M. F. M.; Hunt, H. E. M.
2006-06-01
One of the major sources of ground-borne vibration is the running of trains in underground railway tunnels. Vibration is generated at the wheel-rail interface, from where it propagates through the tunnel and surrounding soil into nearby buildings. An understanding of the dynamic interfaces between track, tunnel and soil is essential before engineering solutions to the vibration problem can be found. A new method has been developed to evaluate the effectiveness of vibration countermeasures. The method is based on calculating the mean power flow from the tunnel, paying attention to that part of the power which radiates upwards to places where buildings' foundations are expected to be found. The mean power is calculated for an infinite train moving through the tunnel with a constant velocity. An elegant mathematical expression for the mean power flow is derived, which can be used with any underground-tunnel model. To evaluate the effect of vibration countermeasures and track properties on power flow, a comprehensive three-dimensional analytical model is used. It consists of Euler-Bernoulli beams to account for the rails and the track slab. These are coupled in the wavenumber-frequency domain to a thin shell representing the tunnel embedded within an infinite continuum, with a cylindrical cavity representing the surrounding soil.
Mcfarland, E. R.
1981-01-01
A solution method was developed for calculating compressible inviscid flow through a linear cascade of arbitrary blade shapes. The method uses advanced surface singularity formulations which were adapted from those in current external flow analyses. The resulting solution technique provides a fast flexible calculation for flows through turbomachinery blade rows. The solution method and some examples of the method's capabilities are presented.
Simulation of flow across complicated domain between tube bundles by the discrete vortex method
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
On the basis of the analysis of numerical simulation methods for the complicated domain between tube bundles, an improved Lagragian discrete vortex method (DVM) and corresponding algorithm are put forward to solve the practical difficulties of flow across tube bundles. With this method the amount of vortices can be reduced considerably, which makes quick calculation possible. Applied to the practical configuration of horizontal tube bundles, the DVM simulation is carried out and compared with the experimental results. Both the transient flow field and the profile of mean velocity and fluctuations are in good agreement with experimental results, which indicate that the DVM is suitable for the simulation of single-phase flow across tube bundles.
DNS of Flows over Periodic Hills using a Discontinuous-Galerkin Spectral-Element Method
Diosady, Laslo T.; Murman, Scott M.
2014-01-01
Direct numerical simulation (DNS) of turbulent compressible flows is performed using a higher-order space-time discontinuous-Galerkin finite-element method. The numerical scheme is validated by performing DNS of the evolution of the Taylor-Green vortex and turbulent flow in a channel. The higher-order method is shown to provide increased accuracy relative to low-order methods at a given number of degrees of freedom. The turbulent flow over a periodic array of hills in a channel is simulated at Reynolds number 10,595 using an 8th-order scheme in space and a 4th-order scheme in time. These results are validated against previous large eddy simulation (LES) results. A preliminary analysis provides insight into how these detailed simulations can be used to improve Reynoldsaveraged Navier-Stokes (RANS) modeling
Numerical methods for two-phase flow with contact lines
Energy Technology Data Exchange (ETDEWEB)
Walker, Clauido
2012-07-01
This thesis focuses on numerical methods for two-phase flows, and especially flows with a moving contact line. Moving contact lines occur where the interface between two fluids is in contact with a solid wall. At the location where both fluids and the wall meet, the common continuum descriptions for fluids are not longer valid, since the dynamics around such a contact line are governed by interactions at the molecular level. Therefore the standard numerical continuum models have to be adjusted to handle moving contact lines. In the main part of the thesis a method to manipulate the position and the velocity of a contact line in a two-phase solver, is described. The Navier-Stokes equations are discretized using an explicit finite difference method on a staggered grid. The position of the interface is tracked with the level set method and the discontinuities at the interface are treated in a sharp manner with the ghost fluid method. The contact line is tracked explicitly and its dynamics can be described by an arbitrary function. The key part of the procedure is to enforce a coupling between the contact line and the Navier-Stokes equations as well as the level set method. Results for different contact line models are presented and it is demonstrated that they are in agreement with analytical solutions or results reported in the literature.The presented Navier-Stokes solver is applied as a part in a multiscale method to simulate capillary driven flows. A relation between the contact angle and the contact line velocity is computed by a phase field model resolving the micro scale dynamics in the region around the contact line. The relation of the microscale model is then used to prescribe the dynamics of the contact line in the macro scale solver. This approach allows to exploit the scale separation between the contact line dynamics and the bulk flow. Therefore coarser meshes can be applied for the macro scale flow solver compared to global phase field simulations
Navier-Stokes flow field analysis of compressible flow in a high pressure safety relief valve
Vu, Bruce; Wang, Ten-See; Shih, Ming-Hsin; Soni, Bharat
1993-12-01
The objective of this study is to investigate the complex three-dimensional flowfield of an oxygen safety pressure relieve valve during an incident, with a computational fluid dynamic (CFD) analysis. Specifically, the analysis will provide a flow pattern that would lead to the expansion of the eventual erosion pattern of the hardware, so as to combine it with other findings to piece together a most likely scenario for the investigation. The CFD model is a pressure based solver. An adaptive upwind difference scheme is employed for the spatial discretization, and a predictor, multiple corrector method is used for the velocity-pressure coupling. The computational result indicated vortices formation near the opening of the valve which matched the erosion pattern of the damaged hardware.
DVI Film Flow Instability Based on the Normal Mode Analysis
Energy Technology Data Exchange (ETDEWEB)
Lee, Jae Young; Euh, Dong Jin [Handong Global Univ., Pohang (Korea, Republic of)
2013-10-15
In the present paper, as the first step of nonlinear studies, the appearance of the third order spatial differentiation of the film thickness in the wave propagation equation is to be derived. The two-fluid model in the adiabatic condition is employed and normal mode analysis. Interfacial pressure forces between steam and water need to be modeled for this purpose. n the present study, we developed a theoretical basis to study nonlinear wave phenomena on the DVI film flow which highly affect the DVI penetration and liquid droplets entrainment out. We set the hyperbolicity breaking condition by providing the interfacial pressure difference considering the curvature of the reactor vessel. The interfacial pressure difference could generate nonlinear wave such as the horseshoe wave which has been believed as a main source of film break up to produce huge amount of droplets to be entrained out. As a safety injection method, the direct vessel injection has been intensively developed in Korea and employed in the APR1400. The developing efforts were made from the determination of the number, location and size of DVI nozzles to the experimental demonstrations. Experimental facilities with various scales have shown its complicated phenomena due to highly nonlinear interaction between the steam and injected water flow. The injected DVI water forms a film type flow but very unstable due to the unsteady energetic steam flow which find the exits around the shell of the downcomer of the reactor vessel. This steam and liquid film interaction leads to the instability on the surface of the film flow and the waves are highly nonlinear to form undercutting, roll over, and finally droplet releasing. The entrained droplets causes a difficulty in the analysis to estimate the water penetrated into the reactor core to cool the nuclear fuels heated up. Unfortunately, these instabilities on the interface of the DVI liquid film have not been studied appropriately and the conservative
Analysis of Stokes flow through periodic permeable tubules
Directory of Open Access Journals (Sweden)
A.M. Siddiqui
2017-03-01
Full Text Available This article reports the detailed analysis of the Stokes flow through permeable tubes. The objective of this investigation was to search for exact solutions to the Stokes flow and thereby observe the effects on radial flow component, provided the permeability on the tubular surface is an elementary trigonometric function. Mathematical expressions for the pressure distribution, velocity components, volume flux, average wall shear stress and leakage flux are presented explicitly. Graphical analysis of the fluid flow is presented for a set of parametric values. Important conclusions are drawn for Stokes flow through tubes with low as well as high permeability. The classical Poiseuille flow is presented as a limiting case of this immense study of Stokes flow.
Mean flow stability analysis of oscillating jet experiments
Oberleithner, Kilian; Soria, Julio
2014-01-01
Linear stability analysis is applied to the mean flow of an oscillating round jet with the aim to investigate the robustness and accuracy of mean flow stability wave models. The jet's axisymmetric mode is excited at the nozzle lip through a sinusoidal modulation of the flow rate at amplitudes ranging from 0.1 % to 100 %. The instantaneous flow field is measured via particle image velocimetry and decomposed into a mean and periodic part utilizing proper orthogonal decomposition. Local linear stability analysis is applied to the measured mean flow adopting a weakly nonparallel flow approach. The resulting global perturbation field is carefully compared to the measurements in terms of spatial growth rate, phase velocity, and phase and amplitude distribution. It is shown that the stability wave model accurately predicts the excited flow oscillations during their entire growth phase and during a large part of their decay phase. The stability wave model applies over a wide range of forcing amplitudes, showing no pr...
Witzke, V.; Silvers, L. J.; Favier, B.
2016-11-01
Shear flows are ubiquitous in astrophysical objects including planetary and stellar interiors, where their dynamics can have significant impact on thermochemical processes. Investigating the complex dynamics of shear flows requires numerical calculations that provide a long-time evolution of the system. To achieve a sufficiently long lifetime in a local numerical model, the system has to be forced externally. However, at present, there exist several different forcing methods to sustain large-scale shear flows in local models. In this paper, we examine and compare various methods used in the literature in order to resolve their respective applicability and limitations. These techniques are compared during the exponential growth phase of a shear flow instability, such as the Kelvin-Helmholtz (KH) instability, and some are examined during the subsequent non-linear evolution. A linear stability analysis provides reference for the growth rate of the most unstable modes in the system and a detailed analysis of the energetics provides a comprehensive understanding of the energy exchange during the system's evolution. Finally, we discuss the pros and cons of each forcing method and their relation with natural mechanisms generating shear flows.
Logically rectangular mixed methods for Darcy flow on general geometry
Energy Technology Data Exchange (ETDEWEB)
Arbogast, T.; Keenan, P.T.; Wheeler, M.F.; Yotov, I. [Rice Univ., Houston, TX (United States)
1995-12-31
The authors consider an expanded mixed finite element formulation (cell centered finite difference) for Darcy flow with a tensor absolute permeability. The reservoir can be geometrically general with internal features, but the computational domain is rectangular. The method is defined on a curvilinear grid that need not be orthogonal, obtained by mapping the rectangular, computational grid. The original flow problem becomes a similar problem with a modified permeability on the computational grid. Quadrature rules turn the mixed method into a cell-centered finite difference method with a 9 point stencil in 2-D and 19 in 3-D. As shown by theory and experiment, if the modified permeability on the computational domain is smooth, then the convergence rate is optimal and both pressure and velocity are superconvergent at certain points. If not, Lagrange multiplier pressures can be introduced on boundaries of elements so that optimal convergence is retained. This modification presents only small changes in the solution process; in fact, the same parallel domain decomposition algorithms can be applied with little or no change to the code if the modified permeability is smooth over the subdomains. This Lagrange multiplier procedure can be used to extend the difference scheme to multi-block domains, and to give a coupling with unstructured grids. In all cases, the mixed formulation is locally conservative. Computational results illustrate the advantage and convergence of this method.
Methods for blood flow measurements using ultrasound contrast agents
Fowlkes, J. Brian
2003-10-01
Blood flow measurements using ultrasound contrast agents are being investigated for myocardial perfusion and more recently in other organ systems. The methods are based largely on the relative increase in echogenicity due to the concentration of bubbles present in the ultrasound beam. In the simplest form, regional differences in blood volume can be inferred but the possibility exists to extract perfusion from the transit of contrast agent through tissue. Perfusion measurements rely on determining the flux of blood through a tissue volume and as such require knowledge of the fractional blood volume (FBV), i.e., ml blood/g tissue and the rate of exchange, commonly measured as the mean transit time (MTT). This presentation will discuss methods of determining each of these values and their combination to estimate tissue perfusion. Underlying principles of indicator-dilution theory will be provided in the context of ultrasound contrast agents. Current methods for determining MTT will include imaging of the intravenous bolus, in-plane contrast disruption with interval and real-time contrast recovery imaging, and control of contrast agent flow using arterial disruption (contrast interruption). The advantages and limitations of the methods will be examined along with current applications. [Work supported in part by NIH.
Incompressible material point method for free surface flow
Zhang, Fan; Zhang, Xiong; Sze, Kam Yim; Lian, Yanping; Liu, Yan
2017-02-01
To overcome the shortcomings of the weakly compressible material point method (WCMPM) for modeling the free surface flow problems, an incompressible material point method (iMPM) is proposed based on operator splitting technique which splits the solution of momentum equation into two steps. An intermediate velocity field is first obtained by solving the momentum equations ignoring the pressure gradient term, and then the intermediate velocity field is corrected by the pressure term to obtain a divergence-free velocity field. A level set function which represents the signed distance to free surface is used to track the free surface and apply the pressure boundary conditions. Moreover, an hourglass damping is introduced to suppress the spurious velocity modes which are caused by the discretization of the cell center velocity divergence from the grid vertexes velocities when solving pressure Poisson equations. Numerical examples including dam break, oscillation of a cubic liquid drop and a droplet impact into deep pool show that the proposed incompressible material point method is much more accurate and efficient than the weakly compressible material point method in solving free surface flow problems.
A nearly real-time UAV video flow mosaic method
Zheng, H.; Jiang, C.; Sun, M.; Li, X. D.; Xiang, R.; Liu, Lei
2014-12-01
In order to solve the problem of low accuracy and high computation cost of current video mosaic methods, and also to acquire large field of view images by the unmanned aerial vehicles (UAV), which have high accuracy and high resolution, this paper propose a method for near real-time mosaic of video flow, so that we can provide essential reference data for the earthquake relief, as well as post-disaster reconstruction and recovery, in time. In this method, we obtain the flight area scope in the route planning process, and calculate the sizes of each frame with sensor sizes and altitudes. Given an overlap degree, time intervals are calculated, and key frames are extracted. After that, feature points are detected in each frame, and they are matched using Hamming distance. The RANSAC algorithm is then applied to remove error matching and calculate parameters of the transformation model. In one-strip case, the newly extracted frame is taken as the reference image in the first half, while after the middle frame is extracted, it is the reference one until the end. Experimental results show that our method can reduce the cascading error, and improve the accuracy and quality of the mosaic images, near real-time mosaic of aerial video flow is feasible.
Ruzicka, Jaromir Jarda
2016-09-01
Automation of reagent based assays, also known as Flow Analysis, is based on sample processing, in which a sample flows towards and through a detector for monitoring of its components. The Achilles heel of this methodology is that the majority of FA techniques use constant continuous forward flow to transport the sample - an approach which continually consumes reagents and generates chemical waste. Therefore the purpose of this report is to highlight recent developments of flow programming that not only save reagents, but also lead by means of advanced sample processing to selective and sensitive assays based on stop flow measurement. Flow programming combined with a novel approach to data harvesting yields a novel approach to single standard calibration, and avoids interference caused by refractive index. Finally, flow programming is useful for sample preparation, such as rapid, extensive sample dilution. The principles are illustrated by selected references to an available online tutorial http://www.flowinjectiontutorial,com/.
Institute of Scientific and Technical Information of China (English)
Ling Li; Ming-Shun Yuan
2011-01-01
In this paper the effects of hydrophobic wall on skin-friction drag in the channel flow are investigated through large eddy simulation on the basis of weaklycompressible flow equations with the MacCormack's scheme on collocated mesh in the FVM framework. The slip length model is adopted to describe the behavior of the slip velocities in the streamwise and spanwise directions at the interface between the hydrophobic wall and turbulent channel flow. Simulation results are presented by analyzing flow behaviors over hydrophobic wall with the Smagorinky subgrid-scale model and a dynamic model on computational meshes of different resolutions. Comparison and analysis are made on the distributions of timeaveraged velocity, velocity fluctuations, Reynolds stress as well as the skin-friction drag. Excellent agreement between the present study and previous results demonstrates the accuracy of the simple classical second-order scheme in representing turbulent vertox near hydrophobic wall. In addition, the relation of drag reduction efficiency versus time-averaged slip velocity is established. It is also found that the decrease of velocity gradient in the close wall region is responsible for the drag reduction. Considering its advantages of high calculation precision and efficiency, the present method has good prospect in its application to practical projects.
Study on flow stability margin by method of system identification
Energy Technology Data Exchange (ETDEWEB)
Zhang Youjie; Jiang Shengyao [Tsinghua Univ., Beijing, BJ (China). Inst. of Nuclear Energy Technology
1999-11-01
The main objective of the investigation is to develop a practical technology and method in engineering, based on general control theory, for distinguishing two-phase flow stability and identifying the safety margin by using the system identification method. By combining the two-phase flow stability theory in the thermo-physics field with the system stability theory and the system identification method in the field of information science, a thermo-hydraulic experiment technology with a new concept was developed. The experiment was carried out on the thermo-hydraulic test system HRTL-5 which serves as simulator to the primary circulation of the nuclear heating reactor NHR-5 and was used for investigation on its thermo-physical behavior. Reverse repeat pseudo-random sequences which were added to the steady heat flux as input signal sources and measured flow rates as response function were used in the test. The two-phase flow stability and the stability margin of the natural circulation system were investigated by analyzing the system pulse response function, the decay ratio and the stability boundary under different operational conditions. The results are compared with those obtained by using conventional methods. The test method and typical results obtained are presented in this paper. (orig.) [German] Das Hauptziel der Untersuchung ist die Entwicklung einer Technik und eines Verfahrens um - basierend auf allgemeiner Regelungstheorie - die Stabilitaet einer Zweiphasenstroemung zu bestimmen und unter Verwendung von Methoden zur Systemidentifikation Sicherheitsreserven zu ermitteln. Durch Kombination der Theorie der Zweiphasenstroemungsstabilitaet im Bereich der Thermophysik mit der Systemstabilitaetstheorie und der informationstheoretischen Systemidentifikationsmethode wurde eine thermohydraulische Experimentiertechnik neuartigen Konzepts entwickelt. Die Versuche wurden auf dem Thermohydraulikteststand HRTL-5 ausgefuehrt, der dem Primaeranlauf des Heizreaktors HHR-5
ECCS flow verification to support transient analysis
Energy Technology Data Exchange (ETDEWEB)
Kovach, C.; Jacobs, R.H.; Ballard, J.E. [Commonwealth Edison Co., Chicago, IL (United States). Nuclear Fuel Services Dept.
1994-12-31
The RETRAN code has been used to develop a model of the Emergency Core Cooling System (ECCS). The model was developed in order to provide conservative injection flow data to be used in various LOCA and non-LOCA analyses and evaluations and to ensure that ECCS pump runout does not occur. The analyses were also needed in order to address a number of ECCS performance issues identified by Westinghouse. These issues include how previous analyses modeled miniflow, RCP seal injection, ECCS branch line resistance, pump suction boost during recirculation, injection line flow imbalances, and, of particular importance, ECCS flow measurement inaccuracies. In turn, these issues directly impact pump runout concerns, Technical Specification verification, and ECCS injection flow during transient conditions. The RETRAN ECCS model has proven to be quite versatile, easy to use, and requires only minimal information about the physical construction and performance of the ECCS system.
Performance analysis of flow lines with non-linear flow of material
Helber, Stefan
1999-01-01
Flow line design is one of the major tasks in production management. The decision to install a set of machines and buffers is often highly irreversible. It determines both cost and revenue to a large extent. In order to assess the economic impact of any possible flow line design, production rates and inventory levels have to be estimated. These performance measures depend on the allocation of buffers whenever the flow of material is occasionally disrupted, for example due to machine failures or quality problems. The book describes analytical methods that can be used to evaluate flow lines much faster than with simulation techniques. Based on these fast analytical techniques, it is possible to determine a flow line design that maximizes the net present value of the flow line investment. The flow of material through the line may be non-linear, for example due to assembly operations or quality inspections.
Eash, David A.; Barnes, Kimberlee K.
2012-01-01
A statewide study was conducted to develop regression equations for estimating six selected low-flow frequency statistics and harmonic mean flows for ungaged stream sites in Iowa. The estimation equations developed for the six low-flow frequency statistics include: the annual 1-, 7-, and 30-day mean low flows for a recurrence interval of 10 years, the annual 30-day mean low flow for a recurrence interval of 5 years, and the seasonal (October 1 through December 31) 1- and 7-day mean low flows for a recurrence interval of 10 years. Estimation equations also were developed for the harmonic-mean-flow statistic. Estimates of these seven selected statistics are provided for 208 U.S. Geological Survey continuous-record streamgages using data through September 30, 2006. The study area comprises streamgages located within Iowa and 50 miles beyond the State's borders. Because trend analyses indicated statistically significant positive trends when considering the entire period of record for the majority of the streamgages, the longest, most recent period of record without a significant trend was determined for each streamgage for use in the study. The median number of years of record used to compute each of these seven selected statistics was 35. Geographic information system software was used to measure 54 selected basin characteristics for each streamgage. Following the removal of two streamgages from the initial data set, data collected for 206 streamgages were compiled to investigate three approaches for regionalization of the seven selected statistics. Regionalization, a process using statistical regression analysis, provides a relation for efficiently transferring information from a group of streamgages in a region to ungaged sites in the region. The three regionalization approaches tested included statewide, regional, and region-of-influence regressions. For the regional regression, the study area was divided into three low-flow regions on the basis of hydrologic
Finite element analysis of inviscid subsonic boattail flow
Chima, R. V.; Gerhart, P. M.
1981-01-01
A finite element code for analysis of inviscid subsonic flows over arbitrary nonlifting planar or axisymmetric bodies is described. The code solves a novel primitive variable formulation of the coupled irrotationality and compressible continuity equations. Results for flow over a cylinder, a sphere, and a NACA 0012 airfoil verify the code. Computed subcritical flows over an axisymmetric boattailed afterbody compare well with finite difference results and experimental data. Interative coupling with an integral turbulent boundary layer code shows strong viscous effects on the inviscid flow. Improvements in code efficiency and extensions to transonic flows are discussed.
Todinov, Michael T
2013-01-01
Repairable flow networks are a new area of research, which analyzes the repair and flow disruption caused by failures of components in static flow networks. This book addresses a gap in current network research by developing the theory, algorithms and applications related to repairable flow networks and networks with disturbed flows. The theoretical results presented in the book lay the foundations of a new generation of ultra-fast algorithms for optimizing the flow in networks after failures or congestion, and the high computational speed creates the powerful possibility of optimal control
Impedance Flow Cytometry: A Novel Technique in Pollen Analysis.
Heidmann, Iris; Schade-Kampmann, Grit; Lambalk, Joep; Ottiger, Marcel; Di Berardino, Marco
2016-01-01
An efficient and reliable method to estimate plant cell viability, especially of pollen, is important for plant breeding research and plant production processes. Pollen quality is determined by classical methods, like staining techniques or in vitro pollen germination, each having disadvantages with respect to reliability, analysis speed, and species dependency. Analysing single cells based on their dielectric properties by impedance flow cytometry (IFC) has developed into a common method for cellular characterisation in microbiology and medicine during the last decade. The aim of this study is to demonstrate the potential of IFC in plant cell analysis with the focus on pollen. Developing and mature pollen grains were analysed during their passage through a microfluidic chip to which radio frequencies of 0.5 to 12 MHz were applied. The acquired data provided information about the developmental stage, viability, and germination capacity. The biological relevance of the acquired IFC data was confirmed by classical staining methods, inactivation controls, as well as pollen germination assays. Different stages of developing pollen, dead, viable and germinating pollen populations could be detected and quantified by IFC. Pollen viability analysis by classical FDA staining showed a high correlation with IFC data. In parallel, pollen with active germination potential could be discriminated from the dead and the viable but non-germinating population. The presented data demonstrate that IFC is an efficient, label-free, reliable and non-destructive technique to analyse pollen quality in a species-independent manner.
Discounted cash flow valuation methods: Examples of perpetuities, constant growth and general case
Fernandez, Pablo
2005-01-01
This paper explores the discounted cash flow valuation methods. We start the paper with the simplest case: no-growth, perpetual-life companies. Then we will study the continuous growth case and, finally, the general case. The different concepts of cash flow used in company valuation are defined: equity cash flow (ECF), free cash flow (FCF), and capital cash flow (CCF). Then the appropriate discount rate is determined for each cash flow, depending on the valuation method used. Our starting poi...
Discounted cash flow valuation methods: Examples of perpetuities, constant growth and general case
Fernandez, Pablo
2005-01-01
This paper explores the discounted cash flow valuation methods. We start the paper with the simplest case: no-growth, perpetual-life companies. Then we will study the continuous growth case and, finally, the general case. The different concepts of cash flow used in company valuation are defined: equity cash flow (ECF), free cash flow (FCF), and capital cash flow (CCF). Then the appropriate discount rate is determined for each cash flow, depending on the valuation method used. Our starting poi...
Particle-in-cell method in multiphase flow simulations
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)
Continuous flow analysis of labile iron in ice-cores.
Hiscock, William T; Fischer, Hubertus; Bigler, Matthias; Gfeller, Gideon; Leuenberger, Daiana; Mini, Olivia
2013-05-07
The important active and passive role of mineral dust aerosol in the climate and the global carbon cycle over the last glacial/interglacial cycles has been recognized. However, little data on the most important aeolian dust-derived biological micronutrient, iron (Fe), has so far been available from ice-cores from Greenland or Antarctica. Furthermore, Fe deposition reconstructions derived from the palaeoproxies particulate dust and calcium differ significantly from the Fe flux data available. The ability to measure high temporal resolution Fe data in polar ice-cores is crucial for the study of the timing and magnitude of relationships between geochemical events and biological responses in the open ocean. This work adapts an existing flow injection analysis (FIA) methodology for low-level trace Fe determinations with an existing glaciochemical analysis system, continuous flow analysis (CFA) of ice-cores. Fe-induced oxidation of N,N'-dimethyl-p-pheylenediamine (DPD) is used to quantify the biologically more important and easily leachable Fe fraction released in a controlled digestion step at pH ~1.0. The developed method was successfully applied to the determination of labile Fe in ice-core samples collected from the Antarctic Byrd ice-core and the Greenland Ice-Core Project (GRIP) ice-core.
Analysis of chromosome damage for biodosimetry using imaging flow cytometry.
Beaton, L A; Ferrarotto, C; Kutzner, B C; McNamee, J P; Bellier, P V; Wilkins, R C
2013-08-30
The dicentric chromosome assay (DCA), which involves counting the frequency of dicentric chromosomes in mitotic lymphocytes and converting it to a dose-estimation for ionizing radiation exposure, is considered to be the gold standard for radiation biodosimetry. Furthermore, for emergency response, the DCA has been adapted for triage by simplifying the scoring method [1]. With the development of new technologies such as the imaging flow cytometer, it may now be possible to adapt this microscope-based method to an automated cytometry method. This technology allows the sensitivity of microscopy to be maintained while adding the increased throughput of flow cytometry. A new protocol is being developed to adapt the DCA to the imaging cytometer in order to further increase the rapid determination of a biological dose. Peripheral blood mononuclear cells (PBMC) were isolated from ex vivo irradiated whole blood samples using a density gradient separation method and cultured with PHA and Colcemid. After 48h incubation, the chromosomes were isolated, stained for DNA content with propidium iodide (PI) and labelled with a centromere marker. Stained chromosomes were then analyzed on the ImageStream(×) (EMD-Millipore, Billerica, MA). Preliminary results indicate that individual chromosomes can be identified and mono- and dicentric chromosomes can be differentiated by imaging cytometry. A dose response curve was generated using this technology. The details of the method and the dose response curve are presented and compared to traditional microscope scoring. Imaging cytometry is a new technology which enables the rapid, automated analysis of fluorescently labelled chromosomes. Adapting the dicentric assay to this technology has the potential for high throughput analysis for mass casualty events.
Boyajian, R A; Schwend, R B; Wolfe, M M; Bickerton, R E; Otis, S M
1995-01-01
Ultrasound-derived volumetric flow analysis may be useful in answering questions of basic physiological interest in the cerebrovascular circulation. Using this technique, the authors have sought to describe quantitatively the complete concurrent flow relations among all four arteries supplying the brain. The aim of this study of normal subjects was to determine the relative flow contributions of the anterior (internal carotid arteries) and posterior (vertebral arteries) cerebral circulation. Comparisons between the observed and theoretically expected anterior and posterior flow distribution would provide an opportunity to assess traditional rheological conceptions in vivo. Pulsed color Doppler ultrasonography was used to measure mean flow rates in the internal carotid and vertebral arteries in 21 normal adults. The anterior circulation (internal carotid arteries bilaterally) carried 82% of the brain's blood supply and comprised 67% of the total vascular cross-sectional area. These values demonstrate precise concordance between observations in vivo and the theoretically derived (Hagen-Poiseuille) expected flow distribution. These cerebrovascular findings support the traditional conception of macroscopic blood flow. Further studies using ultrasound-derived volumetric analysis of the brain's arterial flow relations may illuminate the vascular pathophysiology underlying aging, cerebral ischemia, and dementias.
Wang, Junjian; Kang, Qinjun; Rahman, Sheik S
2016-01-01
The lattice Boltzmann method (LBM) has experienced tremendous advances and been well accepted as a popular method of simulation of various fluid flow mechanisms on pore scale in tight formations. With the introduction of an effective relaxation time and slip boundary conditions, the LBM has been successfully extended to solve micro-gaseous related transport and phenomena. As gas flow in shale matrix is mostly in the slip flow and transition flow regimes, given the difficulties of experimental techniques to determine extremely low permeability, it appears that the computational methods especially the LBM can be an attractive choice for simulation of these micro-gaseous flows. In this paper an extensive overview on a number of relaxation time and boundary conditions used in LBM-like models for micro-gaseous flow are carried out and their advantages and disadvantages are discussed. Furthermore, potential application of the LBM in flow simulation in shale gas reservoirs on pore scale and representative elementary...
Experimental Validation of Volume of Fluid Method for a Sluice Gate Flow
Directory of Open Access Journals (Sweden)
A. A. Oner
2012-01-01
Full Text Available Laboratory experiments are conducted for 2D turbulent free surface flow which interacts with a vertical sluice gate. The velocity field, on the centerline of the channel flow upstream of the gate is measured using the particle image velocimetry technique. The numerical simulation of the same flow is carried out by solving the governing equations, Reynolds-averaged continuity and Navier-Stokes equations, using finite element method. In the numerical solution of the governing equations, the standard k-ε turbulence closure model is used to define the turbulent viscosity. The measured horizontal velocity distribution at the inflow boundary of the solution domain is taken as the boundary condition. The volume of fluid (VOF method is used to determine the flow profile in the channel. Taking into account of the flow characteristics, the computational domain is divided into five subdomains, each having different mesh densities. Three different meshes with five subdomains are employed for the numerical model. A grid convergence analysis indicates that the discretization error in the predicted velocities on the fine mesh remains within 2%. The computational results are compared with the experimental data, and, the most suitable mesh in predicting the velocity field and the flow profile among the three meshes is selected.
Visualization, Selection, and Analysis of Traffic Flows.
Scheepens, Roeland; Hurter, Christophe; van de Wetering, Huub; van Wijk, Jarke J
2016-01-01
Visualization of the trajectories of moving objects leads to dense and cluttered images, which hinders exploration and understanding. It also hinders adding additional visual information, such as direction, and makes it difficult to interactively extract traffic flows, i.e., subsets of trajectories. In this paper we present our approach to visualize traffic flows and provide interaction tools to support their exploration. We show an overview of the traffic using a density map. The directions of traffic flows are visualized using a particle system on top of the density map. The user can extract traffic flows using a novel selection widget that allows for the intuitive selection of an area, and filtering on a range of directions and any additional attributes. Using simple, visual set expressions, the user can construct more complicated selections. The dynamic behaviors of selected flows may then be shown in annotation windows in which they can be interactively explored and compared. We validate our approach through use cases where we explore and analyze the temporal behavior of aircraft and vessel trajectories, e.g., landing and takeoff sequences, or the evolution of flight route density. The aircraft use cases have been developed and validated in collaboration with domain experts.
Simple and clean determination of tetracyclines by flow injection analysis
Rodríguez, Michael Pérez; Pezza, Helena Redigolo; Pezza, Leonardo
2016-01-01
An environmentally reliable analytical methodology was developed for direct quantification of tetracycline (TC) and oxytetracycline (OTC) using continuous flow injection analysis with spectrophotometric detection. The method is based on the diazo coupling reaction between the tetracyclines and diazotized sulfanilic acid in a basic medium, resulting in the formation of an intense orange azo compound that presents maximum absorption at 434 nm. Experimental design was used to optimize the analytical conditions. The proposed technique was validated over the concentration range of 1 to 40 μg mL- 1, and was successfully applied to samples of commercial veterinary pharmaceuticals. The detection (LOD) and quantification (LOQ) limits were 0.40 and 1.35 μg mL- 1, respectively. The samples were also analyzed by an HPLC method, and the results showed agreement with the proposed technique. The new flow injection method can be immediately used for quality control purposes in the pharmaceutical industry, facilitating monitoring in real time during the production processes of tetracycline formulations for veterinary use.
Directory of Open Access Journals (Sweden)
R. A. Crane
2015-01-01
Full Text Available We present an interrupted-flow centrifugation technique to characterise preferential flow in low permeability media. The method entails a minimum of three phases: centrifuge induced flow, no flow and centrifuge induced flow, which may be repeated several times in order to most effectively characterise multi-rate mass transfer behaviour. In addition, the method enables accurate simulation of relevant in situ total stress conditions during flow by selecting an appropriate centrifugal force level. We demonstrate the utility of the technique for characterising the hydraulic properties of smectite clay dominated core samples. All samples exhibited a non-Fickian tracer breakthrough (early tracer arrival, combined with a decrease in tracer concentration immediately after each period of interrupted-flow. This is indicative of dual (or multi porosity behaviour, with solute migration predominately via advection during induced flow, and via molecular diffusion (between the preferential flow network(s and the low hydraulic conductivity domain during interrupted-flow. Tracer breakthrough curves were simulated using a bespoke dual porosity model with excellent agreement between the data and model output (Nash–Sutcliffe model efficiency coefficient was >0.97 for all samples. In combination interrupted-flow centrifuge experiments and dual porosity transport modelling are shown to be a powerful method to characterise preferential flow in low permeability media.
Particle Methods for Geophysical Flow on the Sphere
Bosler, Peter A.
We present a Lagrangian Particle-Panel Method (LPPM) for geophysical fluid flow on a rotating sphere motivated by problems in atmosphere and ocean dynamics. We focus here on the barotropic vorticity equation and 2D passive scalar advection, as a step towards the development of a new dynamical core for global circulation models. The LPPM method employs the Lagrangian form of the equations of motion. The flow map is discretized as a set of Lagrangian particles and panels. Particle velocity is computed by applying a midpoint rule/point vortex approximation to the Biot-Savart integral with quadrature weights determined by the panel areas. We consider several discretizations of the sphere including the cubed sphere mesh, icosahedral triangles, and spherical Voronoi tesselations. The ordinary differential equations for particle motion are integrated by the fourth order Runge-Kutta method. Mesh distortion is addressed using a combination of adaptive mesh refinement (AMR) and a new Lagrangian remeshing procedure. In contrast with Eulerian schemes, the LPPM method avoids explicit discretization of the advective derivative. In the case of passive scalar advection, LPPM preserves tracer ranges and both linear and nonlinear tracer correlations exactly. We present results for the barotropic vorticity equation applied to several test cases including solid body rotation, Rossby-Haurwitz waves, Gaussian vortices, jet streams, and a model for the breakdown of the polar vortex during sudden stratospheric warming events. The combination of AMR and remeshing enables the LPPM scheme to efficiently resolve thin fronts and filaments that develop in the vorticity distribution. We validate the accuracy of LPPM by comparing with results obtained using the Eulerian based Lin-Rood advection scheme. We examine how energy and enstrophy conservation in the LPPM scheme are affected by the time step and spatial discretization. We conclude with a discussion of how the method may be extended to the
ON THE ANALYSIS OF IMPEDANCE-DRIVEN REVERSE FLOW DYNAMICS
Directory of Open Access Journals (Sweden)
LEE V. C.-C.
2017-02-01
Full Text Available Impedance pump is a simple valve-less pumping mechanism, where an elastic tube is joined to a more rigid tube, at both ends. By inducing a periodic asymmetrical compression on the elastic tube will produce a unidirectional flow within the system. This pumping concept offers a low energy, low noise alternative, which makes it an effective driving mechanism, especially for micro-fluidic systems. In addition, the wave-based mechanism through which pumping occurs infers many benefits in terms of simplicity of design and manufacturing. Adjustment of simple parameters such as the excitation frequencies or compression locations will reverse the direction of flow, providing a very versatile range of flow outputs. This paper describes the experimental analysis of such impedance-driven flow with emphasis on the dynamical study of the reverse flow in open-loop environment. In this study, tapered section with converging steps is introduced at both ends of the elastic tube to amplify the magnitude of reverse flow. Study conducted shows that the reverse peak flow is rather significant with estimate of 23% lower than the forward peak flow. The flow dynamics on the other hand has shown to exhibit different characteristics as per the forward peak flow. The flow characteristics is then studied and showed that the tapered sections altered the impedance within the system and hence induce a higher flow in the reverse direction.
Probabilistic power flow using improved Monte Carlo simulation method with correlated wind sources
Bie, Pei; Zhang, Buhan; Li, Hang; Deng, Weisi; Wu, Jiasi
2017-01-01
Probabilistic Power Flow (PPF) is a very useful tool for power system steady-state analysis. However, the correlation among different random injection power (like wind power) brings great difficulties to calculate PPF. Monte Carlo simulation (MCS) and analytical methods are two commonly used methods to solve PPF. MCS has high accuracy but is very time consuming. Analytical method like cumulants method (CM) has high computing efficiency but the cumulants calculating is not convenient when wind power output does not obey any typical distribution, especially when correlated wind sources are considered. In this paper, an Improved Monte Carlo simulation method (IMCS) is proposed. The joint empirical distribution is applied to model different wind power output. This method combines the advantages of both MCS and analytical method. It not only has high computing efficiency, but also can provide solutions with enough accuracy, which is very suitable for on-line analysis.
SWOT ANALYSIS ON SAMPLING METHOD
Directory of Open Access Journals (Sweden)
CHIS ANCA OANA
2014-07-01
Full Text Available Audit sampling involves the application of audit procedures to less than 100% of items within an account balance or class of transactions. Our article aims to study audit sampling in audit of financial statements. As an audit technique largely used, in both its statistical and nonstatistical form, the method is very important for auditors. It should be applied correctly for a fair view of financial statements, to satisfy the needs of all financial users. In order to be applied correctly the method must be understood by all its users and mainly by auditors. Otherwise the risk of not applying it correctly would cause loose of reputation and discredit, litigations and even prison. Since there is not a unitary practice and methodology for applying the technique, the risk of incorrectly applying it is pretty high. The SWOT analysis is a technique used that shows the advantages, disadvantages, threats and opportunities. We applied SWOT analysis in studying the sampling method, from the perspective of three players: the audit company, the audited entity and users of financial statements. The study shows that by applying the sampling method the audit company and the audited entity both save time, effort and money. The disadvantages of the method are difficulty in applying and understanding its insight. Being largely used as an audit method and being a factor of a correct audit opinion, the sampling method’s advantages, disadvantages, threats and opportunities must be understood by auditors.
Business Optimization Research to Work Flow Based on Process Analysis Method%基于工序分析方法的企业生产流程优化研究
Institute of Scientific and Technical Information of China (English)
张学龙
2012-01-01
运用工序分析方法对GL公司核心产品的加工平面布局和生产流程进行优化和再设计,分析加工车间布局的现状图,构建其优化图,优化设计生产流程.提出通过调整工序顺序、优化平面布局、加强作业人员规范操作培训等措施,来消除制造过程中的信息阻塞,使得工序总数减少了7个,搬运的距离缩减了74.9m,作业人员减少了5人,停滞的时间减少了138min,日产能提升108件.实践结果表明:在企业产品制造流程优化过程中,工序分析方法是消除信息阻塞、降低库存、产能提升、实施精益制造的一个有效工具.%The processing layout and production process of GL company's core products is optimized and re-designed by using process analysis method. The present map and optimum proposal of workshop layout are drawn, and work flow is optimal and designed By adjusting the process order, optimizing the layout,and enhancing the operations personnel training and standards so on,information block is eliminated, and the total number of processes is reduced seven steps, and transport distance is reduced 74. 9m, the number of operating personnel is decreased five,and stagnation time is lessen 138min,and capacity of every day is raised 108 parts. The results show that in the process of product process optimization, and process analysis is a powerful tool for eliminating the information block, reducing inventory, raising production capacity, and implementing lean manufacturing during the course of products manufacturing process in enterprises.
Prospects for Eulerian CFD analysis of helicopter vortex flows
Drela, Mark; Murman, Earll M.
1987-01-01
The applicability of current finite-volume CFD algorithms based on the Euler equations to the vortex flow over a helicopter in forward flight is investigated analytically. The general characteristics of the flow are reviewed; existing Euler, Navier-Stokes, perturbation, high-order, and adaptive methods are briefly characterized; and a novel Eulerian/Lagrangian approach with entropy and vorticity corrections is presented in detail. Numerical results for simple convection of a finite-core Lamb vortex moving downstream with its axis perpendicular to the flow are presented in graphs, and the possibility of extending the method to three-dimensional, viscous, and shock flows is discussed.
Prediction of fluid flow in curved pipe using the finite element method
Maitin, Christopher B.
1987-04-01
An analysis of turbulent flow through curved pipes was attempted using the finite element method. A commercial finite element code, FIDAP, which employs the kappa-epsilon model was used. Mesh configurations were developed for three curved pipes with varying bend angles. A pipe with a 180 deg bend was modeled after an experiment to verify the results of the computer code. A 90 deg and 45 deg pipe were modeled at a bend radius of 1 pipe diameter, to simulate standard pipes in ventilation systems. The intent of the study was to examine the flow profiles exiting the bend. The results should give some explanation of the effect of bends on the poor performance of fans placed downstream of bends. The turbulent model failed to converge for a steady-state analysis of the curved pipe flow, so a laminar flow analysis was done. The results show the expected distortion in the velocity profiles exiting from the bends. Also some conclusions were drawn about attaining better convergence with curved pipe flow.
Fast multipole method applied to Lagrangian simulations of vortical flows
Ricciardi, Túlio R.; Wolf, William R.; Bimbato, Alex M.
2017-10-01
Lagrangian simulations of unsteady vortical flows are accelerated by the multi-level fast multipole method, FMM. The combination of the FMM algorithm with a discrete vortex method, DVM, is discussed for free domain and periodic problems with focus on implementation details to reduce numerical dissipation and avoid spurious solutions in unsteady inviscid flows. An assessment of the FMM-DVM accuracy is presented through a comparison with the direct calculation of the Biot-Savart law for the simulation of the temporal evolution of an aircraft wake in the Trefftz plane. The role of several parameters such as time step restriction, truncation of the FMM series expansion, number of particles in the wake discretization and machine precision is investigated and we show how to avoid spurious instabilities. The FMM-DVM is also applied to compute the evolution of a temporal shear layer with periodic boundary conditions. A novel approach is proposed to achieve accurate solutions in the periodic FMM. This approach avoids a spurious precession of the periodic shear layer and solutions are shown to converge to the direct Biot-Savart calculation using a cotangent function.
Multi-scale simulation method for electroosmotic flows
Guo, Lin; Chen, Shiyi; Robbins, Mark O.
2016-10-01
Electroosmotic transport in micro-and nano- channels has important applications in biological and engineering systems but is difficult to model because nanoscale structure near surfaces impacts flow throughout the channel. We develop an efficient multi-scale simulation method that treats near-wall and bulk subdomains with different physical descriptions and couples them through a finite overlap region. Molecular dynamics is used in the near-wall subdomain where the ion density is inconsistent with continuum models and the discrete structure of solvent molecules is important. In the bulk region the solvent is treated as a continuum fluid described by the incompressible Navier-Stokes equations with thermal fluctuations. A discrete description of ions is retained because of the low density of ions and the long range of electrostatic interactions. A stochastic Euler-Lagrangian method is used to simulate the dynamics of these ions in the implicit continuum solvent. The overlap region allows free exchange of solvent and ions between the two subdomains. The hybrid approach is validated against full molecular dynamics simulations for different geometries and types of flows.
Debris flow impact on mitigation barriers: a new method for particle-fluid-structure interactions
Marchelli, Maddalena; Pirulli, Marina; Pudasaini, Shiva P.
2016-04-01
Channelized debris-flows are a type of mass movements that involve water-charged, predominantly coarse-grained inorganic and organic material flowing rapidly down steep confined pre-existing channels (Van Dine, 1985). Due to their rapid movements and destructive power, structural mitigation measures have become an integral part of counter measures against these phenomena, to mitigate and prevent damages resulting from debris-flow impact on urbanized areas. In particular, debris barriers and storage basins, with some form of debris-straining structures incorporated into the barrier constructed across the path of a debris-flow, have a dual role to play: (1) to stimulate deposition by presenting a physical obstruction against flow, and (2) to guarantee that during normal conditions stream water and bedload can pass through the structure; while, during and after an extreme event, the water that is in the flow and some of the fine-grained sediment can escape. A new method to investigate the dynamic interactions between the flowing mass and the debris barrier is presented, with particular emphasis on the effect of the barrier in controlling the water and sediment content of the escaping mass. This aspect is achieved by implementing a new mechanical model into an enhanced two-phase dynamical mass flow model (Pudasaini, 2012), in which solid particles mixture and viscous fluid are taken into account. The complex mechanical model is defined as a function of the energy lost during impact, the physical and geometrical properties of the debris barrier, separate but strongly interacting dynamics of boulder and fluid flows during the impact, particle concentration distribution, and the slope characteristics. The particle-filtering-process results in a large variation in the rheological properties of the fluid-dominated escaping mass, including the substantial reduction in the bulk density, and the inertial forces of the debris-flows. Consequently, the destructive power and run
Institute of Scientific and Technical Information of China (English)
高瑞; 马红燕; 孙雪花; 田锐
2011-01-01
The fluorescent characteristic of the colour reaction between dioxopromethaine hydrochloride and sulfuric acid has been studied. The experiment results indicated that dioxopromethaine hydrochloride was a weak fluorescent substance and could react with sulfuric acid to form an intense fluorescent substance. Combined with flow injection analysis and time scanning technology, a new flowinjection fluorescence method for the determination of dioxopromethaine hydrochloride was established. The experimental conditions that influence the fluorescence intensity were investigated and optimized. The excitation and emission wavelengths were 274.0 and 376.0 nm, respectively. The linear range was 2.8 × 10-7～ 4. O× 10-5 g/mL with the detection limit of 1. 1 × 10-8 g/mL. The relative standard derivation was 0. 5％ (n = 11, c＝ 1. 2 × 10-6 g/mL), the frequency of sample introduction was 100 samples/h. The method has been used for the determination of dioxopromethaine hydrochloride in tablets and human urines with satisfactory results.%研究了硫酸颜色反应用于盐酸二氧丙嗪荧光测定的方法.盐酸二氧丙嗪与浓硫酸反应后,诱发产生强荧光.结合流动注射进样技术,借助时间扫描荧光方式,提出了流动注射时间扫描荧光分析法测定盐酸二氧丙嗪的新方法.体系最大激发和发射波长分别为274.0 nm和376.0 nm.盐酸二氧丙嗪浓度在2.8×10-7～4.0×10-5g/mL范围内与荧光强度呈良好的线性关系,相关系数为0.9998,方法检出限为1.1×10-8g/mL,相对标准偏差为0.5%(n=11,c=1.2×10-6g/mL),进样频率为100次/小时.方法用于药物制剂及尿样中盐酸二氧丙嗪的直接测定,结果满意.
Load flow analysis for variable speed offshore wind farms
DEFF Research Database (Denmark)
Chen, Zhe; Zhao, Menghua; Blaabjerg, Frede
2009-01-01
A serial AC-DC integrated load flow algorithm for variable speed offshore wind farms is proposed. It divides the electrical system of a wind farm into several local networks, and different load flow methods are used for these local networks sequentially. This method is fast, more accurate, and many...... and integrated into the load flow algorithm: one takes into account the control strategy of converters and the other considers the power losses of converters. In addition, different types of variable speed wind turbine systems with different control methods are investigated. Finally, the method is demonstrated...
Statistical methods for bioimpedance analysis
Directory of Open Access Journals (Sweden)
Christian Tronstad
2014-04-01
Full Text Available This paper gives a basic overview of relevant statistical methods for the analysis of bioimpedance measurements, with an aim to answer questions such as: How do I begin with planning an experiment? How many measurements do I need to take? How do I deal with large amounts of frequency sweep data? Which statistical test should I use, and how do I validate my results? Beginning with the hypothesis and the research design, the methodological framework for making inferences based on measurements and statistical analysis is explained. This is followed by a brief discussion on correlated measurements and data reduction before an overview is given of statistical methods for comparison of groups, factor analysis, association, regression and prediction, explained in the context of bioimpedance research. The last chapter is dedicated to the validation of a new method by different measures of performance. A flowchart is presented for selection of statistical method, and a table is given for an overview of the most important terms of performance when evaluating new measurement technology.
Finite Spectral Semi-Lagrangian Method for Incompressible Flows
Institute of Scientific and Technical Information of China (English)
LI Shao-Wu; WANG Jian-Ping
2012-01-01
A new semi-Lagrangian (SL) scheme is proposed by using finite spectral regional interpolation and adequate numerical dissipation to control the nonlinear instability. The finite spectrai basis function is C1 continuous at the boundary and is easy to construct. Comparison between numerical and experimental results indicates that the present method works well in solving incompressible Navier-Stokes equations for unsteady Sows around airfoil with different angles of attack.%A new semi-Lagrangian (SL) scheme is proposed by using finite spectral regional interpolation and adequate numerical dissipation to control the nonlinear instability.The finite spectral basis function is C1 continuous at the boundary and is easy to construct.Comparison between numerical and experimental results indicates that the present method works well in solving incompressible Navier-Stokes equations for unsteady flows around airfoil with different angles of attack.
Flow resistance and its prediction methods in compound channels
Institute of Scientific and Technical Information of China (English)
Kejun Yang; Shuyou Cao; Xingnian Liu
2007-01-01
A series of experiments was carried out in a large symmetric compound channel composed of a rough main channel and rough floodplains to investigate the resistance characteristics of inbank and overbank flows.The effective Manning,Darcy-Weisbach,Chezy coefficients and the relative Nikuradse roughness height were analyzed.Many different representative methods for predicting the composite roughness were systemat-ically summarized.Besides the measured data,a vast number of laboratory data and field data for compoundchannels were collected and used to check the valid-ity of these methods for different subsection divisionsincluding the vertical,horizontal,diagonal and bisec-tional divisions.The computation showed that thesemethods resulted in big errors in assessing the compos-ite roughness in compound channels,and the reasonswere analyzed in detail.The error magnitude is relatedto the subsection divisions.
Dynamic economic dispatch combining network flow and interior point method
Institute of Scientific and Technical Information of China (English)
韩学山; 赵建国; 柳焯
2003-01-01
Under the environment of electric power market, economic dispatch (ED) problem should consider network constraints, unit ramp rates, besides the basic constraints. For this problem, it is important to establish the effective model and algorithm. This paper examines the decoupled conditions that affect the solution optimality to this problem. It proposes an effective model and solution method. Based on the look-ahead technique, it finds the number of time intervals to guarantee the solution optimality. Next, an efficient technique for finding the optimal solution via the interior point methods is described. Test cases, which include dispatching six units over 5 time intervals on the IEEE 30 test system with line flows and ramp constraints are presented. Results indicate that the computational effort as measured by iteration counts or execution time varies only modestly with the problem size.
A rotational compressible inverse design method for internal flow configurations
Dedoussis, V.; Chaviaropoulos, P.; Papailiou, K. D.
The development of a rotational inviscid compressible inverse design method for two-dimensional internal flow configurations is described. Rotationality is due to an incoming entropy gradient, while total enthalpy is considered to be constant throughout the flowfield. The method is based on the potential function-streamfunction formulation. A novel procedure based on differential geometry arguments is employed to derive the governing equation for velocity by requiring the curvature of the two-dimensional Euclidean space to be zero. The velocity equation solved in conjunction with a transport equation for a thermal drift function provide the flowfield without any geometry feedback. An auxiliary orthogonal computational grid adapted to the solution is employed. Geometry is determined by integrating Frenet equations of the grid lines. Inverse calculation results are compared with results of direct reproduction calculations.
Adaptive discontinuous Galerkin methods for non-linear reactive flows
Uzunca, Murat
2016-01-01
The focus of this monograph is the development of space-time adaptive methods to solve the convection/reaction dominated non-stationary semi-linear advection diffusion reaction (ADR) equations with internal/boundary layers in an accurate and efficient way. After introducing the ADR equations and discontinuous Galerkin discretization, robust residual-based a posteriori error estimators in space and time are derived. The elliptic reconstruction technique is then utilized to derive the a posteriori error bounds for the fully discrete system and to obtain optimal orders of convergence. As coupled surface and subsurface flow over large space and time scales is described by (ADR) equation the methods described in this book are of high importance in many areas of Geosciences including oil and gas recovery, groundwater contamination and sustainable use of groundwater resources, storing greenhouse gases or radioactive waste in the subsurface.