Numerical study of transient nonlinear harbor resonance
无
2010-01-01
It is generally accepted that nonlinear wave-wave interactions play an important role in harbor resonance. Nevertheless it is not clear how waves take part in those interactions. The aim of this paper is to investigate those processes for a rectangular harbor at transient phases. Long-period oscillations excited by bichromatic waves are simulated by the Boussinesq model. The simulations start from calm conditions for the purpose of studying the response process. The internal wavemaker stops working after the oscillations have reached a quasi-steady state, and it is used to simulate the damp process. In order to analyze temporary features of wave-wave interactions in different states, the wavelet-based bispectrum is employed. The influence of the short wave frequencies on long-period oscillations is investigated, and reasons are tried to be given from nonlinear triad interactions between different wave components and the interaction of short waves and the bay entrance. Finally, the response time and the damp time are estimated by a simple method.
Khabaza, I M
1960-01-01
Numerical Analysis is an elementary introduction to numerical analysis, its applications, limitations, and pitfalls. Methods suitable for digital computers are emphasized, but some desk computations are also described. Topics covered range from the use of digital computers in numerical work to errors in computations using desk machines, finite difference methods, and numerical solution of ordinary differential equations. This book is comprised of eight chapters and begins with an overview of the importance of digital computers in numerical analysis, followed by a discussion on errors in comput
Inner Harbor Navigation Canal Basin Velocity Analysis
2014-10-01
ER D C/ CH L TR -1 4- 12 Inner Harbor Navigation Canal Basin Velocity Analysis Co as ta l a nd H yd ra ul ic s La bo ra to ry...library at http://acwc.sdp.sirsi.net/client/default. ERDC/CHL TR-14-12 October 2014 Inner Harbor Navigation Canal Basin Velocity Analysis...system of levees, gates, and drainage structures in the Inner Harbor Navigation Canal (IHNC) basin and the greater New Orleans, Louisiana, area. Two
Rao, G Shanker
2006-01-01
About the Book: This book provides an introduction to Numerical Analysis for the students of Mathematics and Engineering. The book is designed in accordance with the common core syllabus of Numerical Analysis of Universities of Andhra Pradesh and also the syllabus prescribed in most of the Indian Universities. Salient features: Approximate and Numerical Solutions of Algebraic and Transcendental Equation Interpolation of Functions Numerical Differentiation and Integration and Numerical Solution of Ordinary Differential Equations The last three chapters deal with Curve Fitting, Eigen Values and Eigen Vectors of a Matrix and Regression Analysis. Each chapter is supplemented with a number of worked-out examples as well as number of problems to be solved by the students. This would help in the better understanding of the subject. Contents: Errors Solution of Algebraic and Transcendental Equations Finite Differences Interpolation with Equal Intervals Interpolation with Unequal Int...
Scott, L Ridgway
2011-01-01
Computational science is fundamentally changing how technological questions are addressed. The design of aircraft, automobiles, and even racing sailboats is now done by computational simulation. The mathematical foundation of this new approach is numerical analysis, which studies algorithms for computing expressions defined with real numbers. Emphasizing the theory behind the computation, this book provides a rigorous and self-contained introduction to numerical analysis and presents the advanced mathematics that underpin industrial software, including complete details that are missing from m
Brezinski, C
2012-01-01
Numerical analysis has witnessed many significant developments in the 20th century. This book brings together 16 papers dealing with historical developments, survey papers and papers on recent trends in selected areas of numerical analysis, such as: approximation and interpolation, solution of linear systems and eigenvalue problems, iterative methods, quadrature rules, solution of ordinary-, partial- and integral equations. The papers are reprinted from the 7-volume project of the Journal of Computational and Applied Mathematics on '/homepage/sac/cam/na2000/index.html<
Jacques, Ian
1987-01-01
This book is primarily intended for undergraduates in mathematics, the physical sciences and engineering. It introduces students to most of the techniques forming the core component of courses in numerical analysis. The text is divided into eight chapters which are largely self-contained. However, with a subject as intricately woven as mathematics, there is inevitably some interdependence between them. The level of difficulty varies and, although emphasis is firmly placed on the methods themselves rather than their analysis, we have not hesitated to include theoretical material when we consider it to be sufficiently interesting. However, it should be possible to omit those parts that do seem daunting while still being able to follow the worked examples and to tackle the exercises accompanying each section. Familiarity with the basic results of analysis and linear algebra is assumed since these are normally taught in first courses on mathematical methods. For reference purposes a list of theorems used in the t...
A composite numerical model for wave diffraction in a harbor with varying water depth
ZHAO Ming; TENG Bin
2004-01-01
A composite numerical model is presented for computing the wave field in a harbor. The mild slope equation is discretized by a finite element method in the domain concerned. Out of the computational domain, the water depth is assumed to be constant. The boundary element method is applied to the outer boundary for dealing with the infinite boundary condition. Because the model satisfies strictly the infinite boundary condition, more accurate results can be obtained. The model is firstly applied to compute the wave diffraction in a narrow rectangular bay and the wave diffraction from a porous cylinder. The numerical results are compared with the analytical solution, experimental data and other numerical results. Good agreements are obtained. Then the model is applied to computing the wave diffraction in a square harbor with varying water depth. The effects of the water depth in the harbor and the incoming wave direction on the wave height distribution are discussed.
A three-dimensional coupled numerical model of nonlinear waves in a harbor
L.G.THAM
2008-01-01
A 3-D time-domain numerical coupled model for nonlinear waves acting on a ship in a harbor has been developed in the present study.The whole domain is divided into the inner domain and the outer domain.The inner domain is the area around the ship,where the flow is expressed by the Laplace equation and numerically solved by the finite element method.The other area is the outer domain,where the flow is described by the higher-order Boussinesq equations and numerically solved by the finite difference method.The matching conditions on the interfaces between the inner domain and the outer domain,the procedure of coupled solution,the length of common domain and the mesh generation in the inner domain are discussed in detail.The other coupled model with the flow in the inner domain governed by the simplified linear Euler equations and relevant physical experiment are adopted to validate the present coupled model,and it is shown that the numerical results of the present model agree with the experimental data,so the present model can be used for the study on the effect of nonlinear waves acting on a fixed ship in a large area and provide a reference for the time-domain simulation of nonlinear wave forces on an arbitrary object in a large harbor and the 3-D district computation in the future.
Introductory numerical analysis
Pettofrezzo, Anthony J
2006-01-01
Written for undergraduates who require a familiarity with the principles behind numerical analysis, this classical treatment encompasses finite differences, least squares theory, and harmonic analysis. Over 70 examples and 280 exercises. 1967 edition.
Numerical Simulation of Borehole Flow in Deep Monitor Wells, Pearl Harbor Aquifer, Oahu, Hawaii
Rotzoll, K.; Oki, D. S.; El-Kadi, A. I.
2010-12-01
Salinity profiles collected from uncased deep monitor wells are commonly used to monitor freshwater-lens thickness in coastal aquifers. However, vertical flow in these wells can cause the measured salinity to differ from salinity in the adjacent aquifer. Substantial borehole flow has been observed in uncased wells in the Pearl Harbor aquifer, Oahu, Hawaii. A numerical modeling approach, incorporating aquifer hydraulic characteristics and recharge rates representative of the Pearl Harbor aquifer, was used to evaluate the effects of borehole flow on measured salinity profiles from deep monitor wells. Borehole flow caused by vertical hydraulic gradients associated with the natural regional groundwater-flow system and local groundwater withdrawals was simulated. Model results were used to estimate differences between vertical salinity profiles in deep monitor wells and the adjacent aquifer in areas of downward, horizontal, and upward flow within the regional flow system—for cases with and without nearby pumped wells. Aquifer heterogeneity, represented in the model as layers of contrasting permeability, was incorporated in model scenarios. Results from this study provide insight into the magnitude of the differences between vertical salinity profiles from deep monitor wells and the salinity distributions in the aquifers. These insights are relevant and are critically needed for management and predictive modeling purposes.
Static Analysis Numerical Algorithms
2016-04-01
STATIC ANALYSIS OF NUMERICAL ALGORITHMS KESTREL TECHNOLOGY, LLC APRIL 2016 FINAL TECHNICAL REPORT APPROVED FOR PUBLIC RELEASE; DISTRIBUTION...3. DATES COVERED (From - To) NOV 2013 – NOV 2015 4. TITLE AND SUBTITLE STATIC ANALYSIS OF NUMERICAL ALGORITHMS 5a. CONTRACT NUMBER FA8750-14-C... algorithms , linear digital filters and integrating accumulators, modifying existing versions of Honeywell’s HiLiTE model-based development system and
Theoretical numerical analysis
Wendroff, Burton
1966-01-01
Theoretical Numerical Analysis focuses on the presentation of numerical analysis as a legitimate branch of mathematics. The publication first elaborates on interpolation and quadrature and approximation. Discussions focus on the degree of approximation by polynomials, Chebyshev approximation, orthogonal polynomials and Gaussian quadrature, approximation by interpolation, nonanalytic interpolation and associated quadrature, and Hermite interpolation. The text then ponders on ordinary differential equations and solutions of equations. Topics include iterative methods for nonlinear systems, matri
Numerical model for sedimentation in the access channel and harbor basin of Belawan Port
Hang Tuah. Salim
2010-01-01
Belawan is the largest port serving North Sumatra for the import and export.Port has facilities for handling container, CPO liquid bulk cargo,Oil,and other agriculture products.Its location is at the fiver mouth which is subjected to the heavy sedimentation especially after many deforestation activities in its catchment area. The numerical modeling was developed for predicting the rate of sediment caused by erosion in the catchment area for several scenarios.This predicted rate of sediment was applied as input to model of sedimentation in the ocean.Present condition of sedimentation data was used as calibrated data.This integrated model was used to simulate the sedimentation in Belawan access channel and harbor basin for several development plans.
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.
Anastassiou, George A
2015-01-01
This is the first numerical analysis text to use Sage for the implementation of algorithms and can be used in a one-semester course for undergraduates in mathematics, math education, computer science/information technology, engineering, and physical sciences. The primary aim of this text is to simplify understanding of the theories and ideas from a numerical analysis/numerical methods course via a modern programming language like Sage. Aside from the presentation of fundamental theoretical notions of numerical analysis throughout the text, each chapter concludes with several exercises that are oriented to real-world application. Answers may be verified using Sage. The presented code, written in core components of Sage, are backward compatible, i.e., easily applicable to other software systems such as Mathematica®. Sage is open source software and uses Python-like syntax. Previous Python programming experience is not a requirement for the reader, though familiarity with any programming language is a p...
Numerical analysis II essentials
REA, The Editors of; Staff of Research Education Association
1989-01-01
REA's Essentials provide quick and easy access to critical information in a variety of different fields, ranging from the most basic to the most advanced. As its name implies, these concise, comprehensive study guides summarize the essentials of the field covered. Essentials are helpful when preparing for exams, doing homework and will remain a lasting reference source for students, teachers, and professionals. Numerical Analysis II covers simultaneous linear systems and matrix methods, differential equations, Fourier transformations, partial differential equations, and Monte Carlo methods.
Numerical modelling and experimentation of oil-spill curtain booms: Application to a harbor
Muttin, F.; Campbell, R.; Ouansafi, A.; Benelmostafa, Y.
2017-01-01
Oil-spill curtain booms are an important response device dedicated to containing and deviating floating pollutants. The hydrodynamic and structural limitations of curtain booms necessitate numerical modelling for efficient usage assessment. A four step model is proposed and applied during an exercise performed in the Galician region of Spain. Experimental results are used to produce a re-analysis of the model and improve contingency planning.
Impact of harbor navigation channels on waves: a numerical modelling guideline
Dusseljee, D.W.; Klopman, G.; Van Vledder, G.P.; Van Riezebos, H.J.
2014-01-01
This study presents an intercomparison of a SWAN and SWASH wave model and 3D laboratory experiments for an existing navigation channel towards a harbor. Results show that the spectral refraction model SWAN underestimates the wave conditions in the channel and at the lee side of the channel especiall
Impact of Harbor Navigation Channels on Waves: a Numerical Modelling Guideline
Dusseljee, D.W.; Klopman, G.; Van Vledder, G.P.; Riezebos, H.J.
2014-01-01
This study presents an intercomparison of a SWAN and SWASH wave model and 3D laboratory experiments for an existing navigation channel towards a harbor. Results show that the spectral refraction model SWAN underestimates the wave conditions in the channel and at the lee side of the channel especiall
Introduction to numerical analysis
Hildebrand, F B
1987-01-01
Well-known, respected introduction, updated to integrate concepts and procedures associated with computers. Computation, approximation, interpolation, numerical differentiation and integration, smoothing of data, other topics in lucid presentation. Includes 150 additional problems in this edition. Bibliography.
Handbook of numerical analysis
Ciarlet, Philippe G
Mathematical finance is a prolific scientific domain in which there exists a particular characteristic of developing both advanced theories and practical techniques simultaneously. Mathematical Modelling and Numerical Methods in Finance addresses the three most important aspects in the field: mathematical models, computational methods, and applications, and provides a solid overview of major new ideas and results in the three domains. Coverage of all aspects of quantitative finance including models, computational methods and applications Provides an overview of new ideas an
Damkilde, Lars
2007-01-01
Limit State analysis has a long history and many prominent researchers have contributed. The theoretical foundation is based on the upper- and lower-bound theorems which give a very comprehensive and elegant formulation on complicated physical problems. In the pre-computer age Limit State analysis...
Damkilde, Lars
2007-01-01
Limit State analysis has a long history and many prominent researchers have contributed. The theoretical foundation is based on the upper- and lower-bound theorems which give a very comprehensive and elegant formulation on complicated physical problems. In the pre-computer age Limit State analysis...... also enabled engineers to solve practical problems within reinforced concrete, steel structures and geotechnics....
Shoaling Analysis at Brazos Island, Harbor Inlet, Texas
2015-10-01
Channel Shoaling Project, waves, currents, water levels, bathymetry, and sediment samples are being collected in and around BIH. These data will be... Texas by Ernest R. Smith, Tahirih C. Lackey, David B. King, and Richard Styles PURPOSE: This Coastal and Hydraulics Engineering Technical Note...compared to recent events. INTRODUCTION: Brazos Island Harbor (also called Brazos Santiago Pass) is located on the lower Gulf of Mexico Texas coast
Theoretical numerical analysis a functional analysis framework
Atkinson, Kendall
2005-01-01
This textbook prepares graduate students for research in numerical analysis/computational mathematics by giving to them a mathematical framework embedded in functional analysis and focused on numerical analysis. This helps the student to move rapidly into a research program. The text covers basic results of functional analysis, approximation theory, Fourier analysis and wavelets, iteration methods for nonlinear equations, finite difference methods, Sobolev spaces and weak formulations of boundary value problems, finite element methods, elliptic variational inequalities and their numerical solu
PIV Analysis of Wake Induced by Real Harbor Seal Whiskers
Bunjevac, Joseph; Rinehart, Aidan; Flaherty, Justin; Zhang, Wei
2016-11-01
Harbor Seals are able to accurately detect minute disturbances in the ambient flow using their whiskers, which is attributed to the exceptional capability of the whiskers to suppress vortex-induced vibrations in the wake. To explore potential applications for designing smart devices, such as high-sensitivity underwater flow sensors and drag reduction components, research has studied the role of key parameters of the whisker morphology on wake structure. Due to the inherent variation in size and angle of incidence along the length of whiskers, it is not well understood how a real seal whisker changes wake structure, in particular the vortex shedding behavior. This work aims to understand the flow around a single real seal whisker using Particle Image Velocimetry at low Reynolds numbers (i.e. a few hundred) in a water channel. Variations in flow structure are inspected between several different real whiskers and whisker models. The results will provide insights of the effects of the natural geometry of the harbor seal whiskers on wake flow compared to idealized whisker-like models.
Matlab programming for numerical analysis
Lopez, Cesar
2014-01-01
MATLAB is a high-level language and environment for numerical computation, visualization, and programming. Using MATLAB, you can analyze data, develop algorithms, and create models and applications. The language, tools, and built-in math functions enable you to explore multiple approaches and reach a solution faster than with spreadsheets or traditional programming languages, such as C/C++ or Java. Programming MATLAB for Numerical Analysis introduces you to the MATLAB language with practical hands-on instructions and results, allowing you to quickly achieve your goals. You will first become
Clinical Analysis of Leber's Hereditary Optic Neuropathy Harboring mtDNA Mutation at nt11778
Xinyu Zhang; Qiang Yu; Qingjiong Zhang; Changxian Yi
2001-01-01
Purpose: To improve our diagnostic technique through the analysis of clinical features ofLeber's heredita'y optic neuropathy (LHON) harboring mtDNA point mutation at nt11778. Methods: Detection of nt11778 mutation was performed on 38 patients clinically diagnosed as LHON in our ophthalmic center from year 1998 to 2000. Circumstances of onset and family history were obtained and ophthalmoscopy, fundus fluorescein angiography, visual field and visual evoked potential were performed on all 38 patients. Result: 30 In 38 patients (78.95 % ) harbor nt11778 mutation, including 28 male (93.33%) and 2 female (6.67%). The ratio of affected male to female is 14: 1. Patients harboring nt11778 mutation display typical clinical nanifestations. Ccnclusion: Identification of one of the three LHON specifically associated ntDNA mutations is essential to confirm the diagnosis. Eye Science 2001: 17:31 ～ 34.
A first course in numerical analysis
Ralston, Anthony
2001-01-01
This outstanding text by two well-known authors treats numerical analysis with mathematical rigor, but presents a minimum of theorems and proofs. Oriented toward computer solutions of problems, it stresses error analysis and computational efficiency, and compares different solutions to the same problem.Following an introductory chapter on sources of error and computer arithmetic, the text covers such topics as approximation and algorithms; interpolation; numerical differentiation and numerical quadrature; the numerical solution of ordinary differential equations; functional approximation by l
Numerical Analysis of Multiscale Computations
Engquist, Björn; Tsai, Yen-Hsi R
2012-01-01
This book is a snapshot of current research in multiscale modeling, computations and applications. It covers fundamental mathematical theory, numerical algorithms as well as practical computational advice for analysing single and multiphysics models containing a variety of scales in time and space. Complex fluids, porous media flow and oscillatory dynamical systems are treated in some extra depth, as well as tools like analytical and numerical homogenization, and fast multipole method.
Bromaghin, Jeffrey F.; Lance, Monique M.; Elliott, Elizabeth W.; Jeffries, Steven J.; Acevedo-Gutiérrez, Alejandro; Kennish, John M.
2012-01-01
Harbor seals (Phoca vitulina) are an abundant predator along the west coast of North America, and there is considerable interest in their diet composition, especially in regard to predation on valued fish stocks. Available information on harbor seal diets, primarily derived from scat analysis, suggests that adult salmon (Oncorhynchus spp.), Pacific Herring (Clupea pallasii), and gadids predominate. Because diet assessments based on scat analysis may be biased, we investigated diet composition through quantitative analysis of fatty acid signatures. Blubber samples from 49 harbor seals captured in western North America from haul-outs within the area of the San Juan Islands and southern Strait of Georgia in the Salish Sea were analyzed for fatty acid composition, along with 269 fish and squid specimens representing 27 potential prey classes. Diet estimates varied spatially, demographically, and among individual harbor seals. Findings confirmed the prevalence of previously identified prey species in harbor seal diets, but other species also contributed significantly. In particular, Black (Sebastes melanops) and Yellowtail (S. flavidus) Rockfish were estimated to compose up to 50% of some individual seal diets. Specialization and high predation rates on Black and Yellowtail Rockfish by a subset of harbor seals may play a role in the population dynamics of these regional rockfish stocks that is greater than previously realized.
An introduction to numerical methods and analysis
Epperson, James F
2013-01-01
Praise for the First Edition "". . . outstandingly appealing with regard to its style, contents, considerations of requirements of practice, choice of examples, and exercises.""-Zentralblatt MATH "". . . carefully structured with many detailed worked examples.""-The Mathematical Gazette The Second Edition of the highly regarded An Introduction to Numerical Methods and Analysis provides a fully revised guide to numerical approximation. The book continues to be accessible and expertly guides readers through the many available techniques of numerical methods and analysis. An Introduction to
Osvaldo Faggioni
2013-01-01
Full Text Available Sea level oscillations are the superposition of many contributions. In particular, tide is a sea level up-down water motion basically depending on three different phenomena: the Earth-Moon-Sun gravitational relationship, the water surface fluid reaction to atmospheric meteorological dynamic, and the Newtonian vertical adjustment of the sea surface due to atmospheric pressure variations. The first tide component (astrotide is periodic and well known in all points of the Earth surface; the second one is directly related to the meteorological phenomenon, and then it is foreseeable; the Newtonian component, on the contrary, is not readily predictable by a general hydrostatic law, because the J factor that represents the Newtonian transfer (from the atmospheric weight to the consequent sea level is variable in each harbor area. The analysis of the gravity field permits to forecast the sea level variation due to meteorological tide events, and its metrological analysis highlights a compensation in the inverse hydrobarometric factor to be taken into account to correctly compensate atmospheric pressure variations in semibinding basins. This phenomenon has several consequences in Harbor Waterside management and in water quality control as shown by the reported case studies and introduces a new reference parameter: the so-called Water 1000.
Theory and applications of numerical analysis
Phillips, G M
1996-01-01
This text is a self-contained Second Edition, providing an introductory account of the main topics in numerical analysis. The book emphasizes both the theorems which show the underlying rigorous mathematics andthe algorithms which define precisely how to program the numerical methods. Both theoretical and practical examples are included.* a unique blend of theory and applications* two brand new chapters on eigenvalues and splines* inclusion of formal algorithms* numerous fully worked examples* a large number of problems, many with solutions
Numerical methods in software and analysis
Rice, John R
1992-01-01
Numerical Methods, Software, and Analysis, Second Edition introduces science and engineering students to the methods, tools, and ideas of numerical computation. Introductory courses in numerical methods face a fundamental problem-there is too little time to learn too much. This text solves that problem by using high-quality mathematical software. In fact, the objective of the text is to present scientific problem solving using standard mathematical software. This book discusses numerous programs and software packages focusing on the IMSL library (including the PROTRAN system) and ACM Algorithm
Discrimination and numerical analysis of human pathogenic ...
SERVER
2008-02-19
Feb 19, 2008 ... Numerical analysis of whole-cell protein profiles of all strains revealed 2 .... average linkage method and correlation coefficient distance. ... distance yielded a dendrogam, consisting of two basic .... Candida glabrata: review of.
Design and analysis of numerical experiments
Bowman, K.P.; Sacks, J.; Chang, Yuefang (Univ. of Illinois, Urbana-Champaign (United States))
1993-05-01
Calculations with numerical models are often referred to as numerical experiments, by analogy to classical laboratory experiments. Usually, many numerical experiments are carried out to determine the response of a numerical model to variations of internal or external parameters over some range of interest. If individual experiments are inexpensive to carry out, and if the number of independent parameters is small, it may be possible to search the entire parameter space of the model. This is difficult, however, if the dimension of the parameter space is even moderately large or the codes are expensive to run. In this paper methods are presented for the design and analysis of numerical experiments that are especially useful and efficient in multidimensional parameter spaces. The analysis method, which is similar to kriging in the spatial analysis literature, fits a statistical model to the output of the numerical model. As an example, the method is applied to a fully nonlinear, global, equivalent-barotropic dynamical model. The statistical model also provides estimates of the uncertainty of predicted numerical model output, which can provide guidance on where in the parameter space to conduct further experiments, if necessary. The method can provide major improvements in the efficiency with which numerical sensitivity experiments are conducted. 17 refs., 9 figs., 2 tabs.
基于因子分析法的厦门港竞争力分析%The Analysis of Xiamen Harbor Competitiveness Based of Factor Analysis Method
林秋云
2015-01-01
文中以厦门港作为研究对象，然后运用因子分析法中的主成分分析法，构建评价港口竞争力指标体系，应用spss分析软件对厦门港及其主要竞争港口上海港、高雄港、广州港这四大港口的竞争力展开分析，最终得到四大港口竞争力由大到小的排列顺序。该分析结果有助于厦门港将来选择发展方向，制定发展措施。%The article uses Xiamen Harbor as the research object, and then applies Principal Component Analysis to evaluation Xiamen Harbor competitiveness.First, we establish some evaluation indexes and then use SPSS to analyze Xiamen Harbor and its major competitors including Shanghai Harbor,Kaohsiung Harbor,Guangzhou Harbor.Finally,we have the sequence of the harbors competitiveness.The result is helpful to the future development direction of Xiamen Harbor.
Rotzoll, Kolja
2012-01-01
The Pearl Harbor aquifer in southern O‘ahu is one of the most important sources of freshwater in Hawai‘i. A thick freshwater lens overlays brackish and saltwater in this coastal aquifer. Salinity profiles collected from uncased deep monitor wells (DMWs) commonly are used to monitor freshwater-lens thickness. However, vertical flow in DMWs can cause the measured salinity to differ from salinity in the adjacent aquifer or in an aquifer without a DWM. Substantial borehole flow and displacement of salinity in DMWs over several hundred feet have been observed in the Pearl Harbor aquifer. The objective of this study was to evaluate the effects of borehole flow on measured salinity profiles from DMWs. A numerical modeling approach incorporated aquifer hydraulic characteristics and recharge and withdrawal rates representative of the Pearl Harbor aquifer. Borehole flow caused by vertical hydraulic gradients associated with both the natural regional flow system and groundwater withdrawals was simulated. Model results indicate that, with all other factors being equal, greater withdrawal rates, closer withdrawal locations, or higher hydraulic conductivities of the well cause greater borehole flow and displacement of salinity in the well. Borehole flow caused by the natural groundwater-flow system is five orders of magnitude greater than vertical flow in a homogeneous aquifer, and borehole-flow directions are consistent with the regional flow system: downward flow in inland recharge areas and upward flow in coastal discharge areas. Displacement of salinity inside the DMWs associated with the regional groundwater-flow system ranges from less than 1 to 220 ft, depending on the location and assumed hydraulic conductivity of the well. For example, upward displacements of the 2 percent and 50 percent salinity depths in a well in the coastal discharge part of the flow system are 17 and 4.4 ft, respectively, and the average salinity difference between aquifer and borehole is 0
Mode analysis of numerical geodynamo models
Schrinner, Martin; Hoyng, Peter
2011-01-01
It has been suggested in Hoyng (2009) that dynamo action can be analysed by expansion of the magnetic field into dynamo modes and statistical evaluation of the mode coefficients. We here validate this method by analysing a numerical geodynamo model and comparing the numerically derived mean mode coefficients with the theoretical predictions. The model belongs to the class of kinematically stable dynamos with a dominating axisymmetric, antisymmetric with respect to the equator and non-periodic fundamental dynamo mode. The analysis requires a number of steps: the computation of the so-called dynamo coefficients, the derivation of the temporally and azimuthally averaged dynamo eigenmodes and the decomposition of the magnetic field of the numerical geodynamo model into the eigenmodes. For the determination of the theoretical mode excitation levels the turbulent velocity field needs to be projected on the dynamo eigenmodes. We compare the theoretically and numerically derived mean mode coefficients and find reason...
Parallel Worldline Numerics: Implementation and Error Analysis
Mazur, Dan
2014-01-01
We give an overview of the worldline numerics technique, and discuss the parallel CUDA implementation of a worldline numerics algorithm. In the worldline numerics technique, we wish to generate an ensemble of representative closed-loop particle trajectories, and use these to compute an approximate average value for Wilson loops. We show how this can be done with a specific emphasis on cylindrically symmetric magnetic fields. The fine-grained, massive parallelism provided by the GPU architecture results in considerable speedup in computing Wilson loop averages. Furthermore, we give a brief overview of uncertainty analysis in the worldline numerics method. There are uncertainties from discretizing each loop, and from using a statistical ensemble of representative loops. The former can be minimized so that the latter dominates. However, determining the statistical uncertainties is complicated by two subtleties. Firstly, the distributions generated by the worldline ensembles are highly non-Gaussian, and so the st...
Numerical Analysis of Partial Differential Equations
Lui, S H
2011-01-01
A balanced guide to the essential techniques for solving elliptic partial differential equations Numerical Analysis of Partial Differential Equations provides a comprehensive, self-contained treatment of the quantitative methods used to solve elliptic partial differential equations (PDEs), with a focus on the efficiency as well as the error of the presented methods. The author utilizes coverage of theoretical PDEs, along with the nu merical solution of linear systems and various examples and exercises, to supply readers with an introduction to the essential concepts in the numerical analysis
Comparative analysis of the fecal bacterial community of five harbor seals (Phoca vitulina).
Numberger, Daniela; Herlemann, Daniel P R; Jürgens, Klaus; Dehnhardt, Guido; Schulz-Vogt, Heide
2016-10-01
The gut microbiota has many beneficial effects on host metabolism and health, and its composition is determined by numerous factors. It is also assumed that there was a co-evolution of mammals and the bacteria inhabiting their gut. Current knowledge of the mammalian gut microbiota mainly derives from studies on humans and terrestrial animals, whereas those on marine mammals are sparse. However, they could provide additional information on influencing factors, such as the role of diet and co-evolution with the host. In this study, we investigated and compared the bacterial diversity in the feces of five male harbor seals (Phoca vitulina). Because this small population included two half-brother pairs, each sharing a common father, it allowed an evaluation of the impact of host relatedness or genetic similarity on the gut microbial community. Fresh feces obtained from the seals by an enema were analyzed by fluorescence in situ hybridization and amplicon sequencing of 16S rRNA genes. The results showed that the bacterial communities in the seals' feces mainly consisted of the phyla Firmicutes (19-43%), Bacteroidetes (22-36%), Fusobacteria (18-32%), and Proteobacteria (5-17%) . Twenty-one bacterial members present in the fecal samples of the five seals contributed an average relative abundance of 93.7 + 8.7% of the total fecal microbial community. Contrary to all expectations based on previous studies a comparison of the fecal community between individual seals showed a higher similarity between unrelated than related individuals.
Numerical methods and analysis of multiscale problems
Madureira, Alexandre L
2017-01-01
This book is about numerical modeling of multiscale problems, and introduces several asymptotic analysis and numerical techniques which are necessary for a proper approximation of equations that depend on different physical scales. Aimed at advanced undergraduate and graduate students in mathematics, engineering and physics – or researchers seeking a no-nonsense approach –, it discusses examples in their simplest possible settings, removing mathematical hurdles that might hinder a clear understanding of the methods. The problems considered are given by singular perturbed reaction advection diffusion equations in one and two-dimensional domains, partial differential equations in domains with rough boundaries, and equations with oscillatory coefficients. This work shows how asymptotic analysis can be used to develop and analyze models and numerical methods that are robust and work well for a wide range of parameters.
Numerical Limit Analysis of Precast Concrete Structures
Herfelt, Morten Andersen; Poulsen, Peter Noe; Hoang, Linh Cao
2016-01-01
optimisation as well as material optimisation is given and a four-storey shear wall is analysed using load optimisation. The analysis yields a capacity more than three times larger than the design load for the critical load case, and the collapse mode and stress distribution are analysed. Finally, numerical...
On the Complexity of Numerical Analysis
Miltersen, Peter Bro; Kjeldgaard-Pedersen, Johan; Burgisser, Peter;
2006-01-01
We study two quite different approaches to understanding the complexity of fundamental problems in numerical analysis. We show that both hinge on the question of understanding the complexity of the following problem, which we call PosSLP: Given a division-free straight-line program producing...... of classical complexity classes) being PSPACE....
Johnson, Jennifer, Ed.
1992-01-01
This issue of "Loblolly Magazine" was written in observance of the 50th anniversary of the U.S. entrance into World War II. The publication features interviews conducted by East Texas high school students with Clarence Otterman, one of the few survivors of the crew of the USS Arizona, which was bombed during the attack on Pearl Harbor,…
Manufacturing in space: Fluid dynamics numerical analysis
Robertson, S. J.; Nicholson, L. A.; Spradley, L. W.
1981-01-01
Natural convection in a spherical container with cooling at the center was numerically simulated using the Lockheed-developed General Interpolants Method (GIM) numerical fluid dynamic computer program. The numerical analysis was simplified by assuming axisymmetric flow in the spherical container, with the symmetry axis being a sphere diagonal parallel to the gravity vector. This axisymmetric spherical geometry was intended as an idealization of the proposed Lal/Kroes growing experiments to be performed on board Spacelab. Results were obtained for a range of Rayleigh numbers from 25 to 10,000. For a temperature difference of 10 C from the cooling sting at the center to the container surface, and a gravitional loading of 0.000001 g a computed maximum fluid velocity of about 2.4 x 0.00001 cm/sec was reached after about 250 sec. The computed velocities were found to be approximately proportional to the Rayleigh number over the range of Rayleigh numbers investigated.
Numerical Limit Analysis of Reinforced Concrete Structures
Larsen, Kasper Paaske
methods provide engineers with valuable tools for limit sta- te analysis, their application becomes difficult with increased structural complexity. The main challenge is to solve the optimization problem posed by the extremum principles. This thesis is a study of how numerical methods can be used to solve...... limit state analysis problems. The work focuses on determination of the load bearing capacity of reinforced concrete structures by employing the lower bound theorem and a finite element method using equilibrium elements is developed. The recent year’s development within the field of convex optimization...... is developed for improved perfor- mance. An example is given in which an inverse T-beam is analyzed and the numerical results are compared to laboratory tests. The third and final element is a plane shell element capable of modeling membrane and plate bending behavior. The element employs a layered disk...
Photonic Crystals Mathematical Analysis and Numerical Approximation
Dörfler, Willy; Plum, Michael; Schneider, Guido; Wieners, Christian
2011-01-01
This book concentrates on the mathematics of photonic crystals, which form an important class of physical structures investigated in nanotechnology. Photonic crystals are materials which are composed of two or more different dielectrics or metals, and which exhibit a spatially periodic structure, typically at the length scale of hundred nanometers. In the mathematical analysis and the numerical simulation of the partial differential equations describing nanostructures, several mathematical difficulties arise, e. g., the appropriate treatment of nonlinearities, simultaneous occurrence of contin
An introduction to numerical methods and analysis
Epperson, J F
2007-01-01
Praise for the First Edition "". . . outstandingly appealing with regard to its style, contents, considerations of requirements of practice, choice of examples, and exercises.""-Zentrablatt Math "". . . carefully structured with many detailed worked examples . . .""-The Mathematical Gazette "". . . an up-to-date and user-friendly account . . .""-Mathematika An Introduction to Numerical Methods and Analysis addresses the mathematics underlying approximation and scientific computing and successfully explains where approximation methods come from, why they sometimes work (or d
Analysis of churn and excess material at the Pearl Harbor Naval Shipyard
Cheshure, Kevin; Hunt, Anthony; Bangert, Lawrence
2003-01-01
MBA Professional Report Approved for public release; distribution is unlimited. For a Naval Shipyard, the amount of material ordered after beginning an availability (churn) and the amount of material ordered but not used (excess) are key performance indicators. Pearl Harbor Naval Shipyard's metrics indicate that an average of 50% of material ordered during an availability is ordered after the start of the availability and that 15% of material is excess. The NAVSEA goal for both metrics ...
Numerical analysis method for linear induction machines.
Elliott, D. G.
1972-01-01
A numerical analysis method has been developed for linear induction machines such as liquid metal MHD pumps and generators and linear motors. Arbitrary phase currents or voltages can be specified and the moving conductor can have arbitrary velocity and conductivity variations from point to point. The moving conductor is divided into a mesh and coefficients are calculated for the voltage induced at each mesh point by unit current at every other mesh point. Combining the coefficients with the mesh resistances yields a set of simultaneous equations which are solved for the unknown currents.
Numerical analysis of cross shear plate rolling
Zhang, Wenqi; Bay, Niels
1997-01-01
The rolling process is widely applied for industrial production of metal plates. In conventional plate rolling the two work rolls are rotating at the same peripheral speed. By introducing a specific difference in the speed of the two work rolls, cross shear rolling is introduced forming a central...... are in the roll gap, the position and the size of the shear zone and the rolling load are calculated. Experimental results are presented verifying the calculations. The numerical analysis facilitates a better understanding of the mechanics in cross shear plate rolling....
Numerical analysis of cross shear plate rolling
Zhang, Wenqi; Bay, Niels
1997-01-01
The rolling process is widely applied for industrial production of metal plates. In conventional plate rolling the two work rolls are rotating at the same peripheral speed. By introducing a specific difference in the speed of the two work rolls, cross shear rolling is introduced forming a central...... shear zone between the forward and backward slip zones in the deformation zone thus lowering the rolling load. A numerical analysis of the cross shear rolling process is carried out based on the slab method adopting Wanheim and Bay's general friction model. The pressure distribution along the contact...
Numerical modeling techniques for flood analysis
Anees, Mohd Talha; Abdullah, K.; Nawawi, M. N. M.; Ab Rahman, Nik Norulaini Nik; Piah, Abd. Rahni Mt.; Zakaria, Nor Azazi; Syakir, M. I.; Mohd. Omar, A. K.
2016-12-01
Topographic and climatic changes are the main causes of abrupt flooding in tropical areas. It is the need to find out exact causes and effects of these changes. Numerical modeling techniques plays a vital role for such studies due to their use of hydrological parameters which are strongly linked with topographic changes. In this review, some of the widely used models utilizing hydrological and river modeling parameters and their estimation in data sparse region are discussed. Shortcomings of 1D and 2D numerical models and the possible improvements over these models through 3D modeling are also discussed. It is found that the HEC-RAS and FLO 2D model are best in terms of economical and accurate flood analysis for river and floodplain modeling respectively. Limitations of FLO 2D in floodplain modeling mainly such as floodplain elevation differences and its vertical roughness in grids were found which can be improve through 3D model. Therefore, 3D model was found to be more suitable than 1D and 2D models in terms of vertical accuracy in grid cells. It was also found that 3D models for open channel flows already developed recently but not for floodplain. Hence, it was suggested that a 3D model for floodplain should be developed by considering all hydrological and high resolution topographic parameter's models, discussed in this review, to enhance the findings of causes and effects of flooding.
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.
Crawford, Gregory B.; Admire, Amanda R.; Dengler, Lori A.
2017-08-01
Crescent City, California typically records some of the largest waveheights along the US west coast for far-field tsunami sources and has suffered more loss than any North American site over the past century. We installed a Nortek Acoustic Doppler Profiler (ADP) in Crescent City Harbor in 2014 to better understand variations in water level and currents caused by forcing, such as tsunamis, tides, and weather events. A small tsunami was first detected in the harbor on April 2, 2014 and had a maximum peak-to-trough waveheight of 0.37 m. This event was near the ADP limit of detectability, with a peak observed tsunami current on the order of 0.16 m/s. Spectral analysis of water level and velocities before, during and after the tsunami shows well-defined spectral peaks with periods corresponding to roughly 20 and 5.6 min in both water level and velocity; elevated spectral levels also appear around 10 min, although a consistent peak location was less well defined. An additional peak appeared at around 2.5 min in water level but was not consistently observed in velocity. During the tsunami, spectral levels increased by roughly an order of magnitude around the 20-min peak (averaged over 24 h), with reduced levels at shorter periods. Motions around the 20-min period were aligned roughly NE-SW, approximately along the channel leading into the inner boat basin. At 5.6-min periods, the motion was roughly NW-SE, suggesting a higher-frequency modal response of the harbor.
EMPIRICAL-NUMERICAL ANALYSIS OF HEADCUT MIGRATION
无
2005-01-01
Headcut migration is studied by using empirical and numerical modeling approaches. Empirical formulas for the headcut migration are established using available measurement data, which consider not only the flow strength but also the properties of soil. Numerical model for the headcut migration is proposed. The influences of dynamic pressure gradient, downward flow, and bed slope on sediment entrainment are considered. The local erosion patterns and migration speeds of headcut calculated by the numerical model agree reasonably well with observed data.
Numerical analysis of systems of ordinary and stochastic differential equations
Artemiev, S S
1997-01-01
This text deals with numerical analysis of systems of both ordinary and stochastic differential equations. It covers numerical solution problems of the Cauchy problem for stiff ordinary differential equations (ODE) systems by Rosenbrock-type methods (RTMs).
Postharvest Analysis of Lowland Transgenic Tomato Fruits Harboring hpRNAi-ACO1 Construct
Bita Behboodian
2012-01-01
Full Text Available The plant hormone, ethylene, is an important regulator which involved in regulating fruit ripening and flower senescence. In this study, RNA interference (RNAi technology was employed to silence the genes involved in ethylene biosynthetic pathway. This was achieved by blocking the expression of specific gene encoding the ACC oxidase. Initially, cDNA corresponding to ACO1 of lowland tomato cultivar (MT1, which has high identity with ACO1 of Solanum lycopersicum in GenBank, was cloned through RT-PCR. Using a partial coding region of ACO1, one hpRNAi transformation vector was constructed and expressed ectopically under the 35S promoter. Results showed that transgenic lines harboring the hpRNA-ACO1 construct had lower ethylene production and a longer shelf life of 32 days as compared to 10 days for wild-type fruits. Changes in cell wall degrading enzyme activities were also investigated in cases where the transgenic fruits exhibited reduced rates of firmness loss, which can be associated with a decrease in pectin methylesterase (PME and polygalacturonase (PG activities. However, no significant change was detected in both transgenic and wild-type fruits in terms of β-galactosidase (β-Gal activity and levels of total soluble solid, titratable acid and ascorbic acid.
Evaluation of steel corrosion by numerical analysis
Kawahigashi, Tatsuo
2017-01-01
Recently, various non-destructive and numerical methods have been used and many cases of steel corrosion are examined. For example, methods of evaluating corrosion through various numerical methods and evaluating macrocell corrosion and micro-cell corrosion using measurements have been proposed. However, there are few reports on estimating of corrosion loss with distinguishing the macro-cell and micro-cell corrosion and with resembling an actuality phenomenon. In this study, for distinguishin...
Status of NINJA: the Numerical INJection Analysis project
Aylott, Benjamin; Boggs, William D; Boyle, Michael; Brady, Patrick R; Brown, Duncan A; Brügmann, Bernd; Buchman, Luisa T; Buonanno, Alessandra; Cadonati, Laura; Camp, Jordan; Campanelli, Manuela; Centrella, Joan; Chatterjis, Shourov; Christensen, Nelson; Chu, Tony; Diener, Peter; Dorband, Nils; Etienne, Zachariah B; Faber, Joshua; Fairhurst, Stephen; Farr, Benjamin; Fischetti, Sebastian; Guidi, Gianluca; Goggin, Lisa M; Hannam, Mark; Herrmann, Frank; Hinder, Ian; Husa, Sascha; Kalogera, Vicky; Keppel, Drew; Kidder, Lawrence E; Kelly, Bernard J; Krishnan, Badri; Laguna, Pablo; Lousto, Carlos O; Mandel, Ilya; Marronetti, Pedro; Matzner, Richard; McWilliams, Sean T; Matthews, Keith D; Mercer, R Adam; Mohapatra, Satyanarayan R P; Mroué, Abdul H; Nakano, Hiroyuki; Ochsner, Evan; Pan, Yi; Pekowsky, Larne; Pfeiffer, Harald P; Pollney, Denis; Pretorius, Frans; Raymond, Vivien; Reisswig, Christian; Rezzolla, Luciano; Rinne, Oliver; Robinson, Craig; Röver, Christian; Santamaría, Lucía; Sathyaprakash, Bangalore; Scheel, Mark A; Schnetter, Erik; Seiler, Jennifer; Shapiro, Stuart L; Shoemaker, Deirdre; Sperhake, Ulrich; Stroeer, Alexander; Sturani, Riccardo; Tichy, Wolfgang; Liu, Yuk Tung; van der Sluys, Marc; van Meter, James R; Vaulin, Ruslan; Vecchio, Alberto; Veitch, John; Viceré, Andrea; Whelan, John T; Zlochower, Yosef; 10.1088/0264-9381/26/11/114008
2009-01-01
The 2008 NRDA conference introduced the Numerical INJection Analysis project (NINJA), a new collaborative effort between the numerical relativity community and the data analysis community. NINJA focuses on modeling and searching for gravitational wave signatures from the coalescence of binary system of compact objects. We review the scope of this collaboration and the components of the first NINJA project, where numerical relativity groups shared waveforms and data analysis teams applied various techniques to detect them when embedded in colored Gaussian noise.
M. Boumaza
2015-07-01
Full Text Available Transient convection heat transfer is of fundamental interest in many industrial and environmental situations, as well as in electronic devices and security of energy systems. Transient fluid flow problems are among the more difficult to analyze and yet are very often encountered in modern day technology. The main objective of this research project is to carry out a theoretical and numerical analysis of transient convective heat transfer in vertical flows, when the thermal field is due to different kinds of variation, in time and space of some boundary conditions, such as wall temperature or wall heat flux. This is achieved by the development of a mathematical model and its resolution by suitable numerical methods, as well as performing various sensitivity analyses. These objectives are achieved through a theoretical investigation of the effects of wall and fluid axial conduction, physical properties and heat capacity of the pipe wall on the transient downward mixed convection in a circular duct experiencing a sudden change in the applied heat flux on the outside surface of a central zone.
QCD and numerical analysis III. Proceedings
Borici, A.; Joo, B.; Kennedy, A.; Pendleton, B. (eds.) [Edinburgh Univ. (United Kingdom). School of Physics; Frommer, A. [Bergische Univ. Wuppertal (Germany). Fachbereich C - Mathematik und Naturwissenschaften
2005-07-01
This book reports on progress in numerical methods for Lattice QCD with chiral fermions. It contains a set of pedagogical introductory articles written by experts from both the Applied Mathematics and Lattice Field Theory communities, together with detailed accounts of leading-edge algorithms for the simulation of overlap chiral fermions. Topics covered include: QCD simulations in the chiral regime; Evaluation and approximation of matrix functions; Krylov subspace methods for the iterative solution of linear systems; Eigenvalue solvers. These are complemented by a set of articles on closely related numerical and technical problems in Lattice field Theory. (orig.)
Lecture notes in numerical analysis with Mathematica
Styś, Tadeusz
2014-01-01
The contents of this book include chapters on floating point computer arithmetic, natural and generalized interpolating polynomials, uniform approximation, numerical integration, polynomial splines and many more.This book is intended for undergraduate and graduate students in institutes, colleges, universities and academies who want to specialize in this field. The readers will develop a solid understanding of the concepts of numerical methods and their application. The inclusion of Lagrane and Hermite approximation by polynomials, Trapezian rule, Simpsons rule, Gauss methods and Romberg`s met
Numerical analysis in electromagnetics the TLM method
Saguet, Pierre
2013-01-01
The aim of this book is to give a broad overview of the TLM (Transmission Line Matrix) method, which is one of the "time-domain numerical methods". These methods are reputed for their significant reliance on computer resources. However, they have the advantage of being highly general.The TLM method has acquired a reputation for being a powerful and effective tool by numerous teams and still benefits today from significant theoretical developments. In particular, in recent years, its ability to simulate various situations with excellent precision, including complex materials, has been
Analysis of Numerically Generated Wake Structures
Ivanell, S.; Sørensen, Jens Nørkær; Mikkelsen, Robert Flemming;
2009-01-01
Direct numerical simulations of the Navier-Stokes equations are performed to achieve a better understanding of the behaviour of wakes generated by wind turbines. The simulations are performed by combining the in-house developed computer code EllipSys3D with the actuator-line methodology. In the a......Direct numerical simulations of the Navier-Stokes equations are performed to achieve a better understanding of the behaviour of wakes generated by wind turbines. The simulations are performed by combining the in-house developed computer code EllipSys3D with the actuator-line methodology...
Numerical Analysis of Partial Differential Equations
Lions, Jacques-Louis
2011-01-01
S. Albertoni: Alcuni metodi di calcolo nella teoria della diffusione dei neutroni.- I. Babuska: Optimization and numerical stability in computations.- J.H. Bramble: Error estimates in elliptic boundary value problems.- G. Capriz: The numerical approach to hydrodynamic problems.- A. Dou: Energy inequalities in an elastic cylinder.- T. Doupont: On the existence of an iterative method for the solution of elliptic difference equation with an improved work estimate.- J. Douglas, J.R. Cannon: The approximation of harmonic and parabolic functions of half-spaces from interior data.- B.E. Hubbard: Erro
Comparative analysis of the fecal bacterial community of five harbor seals (Phoca vitulina)
Numberger, Daniela; Herlemann, Daniel P. R.; Jürgens, Klaus; Dehnhardt, Guido; Schulz‐Vogt, Heide
2016-01-01
Abstract The gut microbiota has many beneficial effects on host metabolism and health, and its composition is determined by numerous factors. It is also assumed that there was a co‐evolution of mammals and the bacteria inhabiting their gut. Current knowledge of the mammalian gut microbiota mainly derives from studies on humans and terrestrial animals, whereas those on marine mammals are sparse. However, they could provide additional information on influencing factors, such as the role of diet...
SINFAC - SYSTEMS IMPROVED NUMERICAL FLUIDS ANALYSIS CODE
Costello, F. A.
1994-01-01
The Systems Improved Numerical Fluids Analysis Code, SINFAC, consists of additional routines added to the April 1983 revision of SINDA, a general thermal analyzer program. The purpose of the additional routines is to allow for the modeling of active heat transfer loops. The modeler can simulate the steady-state and pseudo-transient operations of 16 different heat transfer loop components including radiators, evaporators, condensers, mechanical pumps, reservoirs and many types of valves and fittings. In addition, the program contains a property analysis routine that can be used to compute the thermodynamic properties of 20 different refrigerants. SINFAC can simulate the response to transient boundary conditions. SINFAC was first developed as a method for computing the steady-state performance of two phase systems. It was then modified using CNFRWD, SINDA's explicit time-integration scheme, to accommodate transient thermal models. However, SINFAC cannot simulate pressure drops due to time-dependent fluid acceleration, transient boil-out, or transient fill-up, except in the accumulator. SINFAC also requires the user to be familiar with SINDA. The solution procedure used by SINFAC is similar to that which an engineer would use to solve a system manually. The solution to a system requires the determination of all of the outlet conditions of each component such as the flow rate, pressure, and enthalpy. To obtain these values, the user first estimates the inlet conditions to the first component of the system, then computes the outlet conditions from the data supplied by the manufacturer of the first component. The user then estimates the temperature at the outlet of the third component and computes the corresponding flow resistance of the second component. With the flow resistance of the second component, the user computes the conditions down stream, namely the inlet conditions of the third. The computations follow for the rest of the system, back to the first component
Numerical Analysis of Large Diameter Butterfly Valve
Youngchul, Park; Xueguan, Song
In this paper, a butterfly valve with the diameter of 1,800 mm was studied. Three-dimensional numerical technique by using commercial code CFX were conducted to observe the flow patterns and to measure flow coefficient, hydrodynamic torque coefficient and so on, when the large butterfly valve operated with various angles and uniform incoming velocity.
Stochastic Analysis Method of Sea Environment Simulated by Numerical Models
刘德辅; 焦桂英; 张明霞; 温书勤
2003-01-01
This paper proposes the stochastic analysis method of sea environment simulated by numerical models, such as wave height, current field, design sea levels and longshore sediment transport. Uncertainty and sensitivity analysis of input and output factors of numerical models, their long-term distribution and confidence intervals are described in this paper.
Feltus Frank A
2011-07-01
Full Text Available Abstract Background Switchgrass, a C4 species and a warm-season grass native to the prairies of North America, has been targeted for development into an herbaceous biomass fuel crop. Genetic improvement of switchgrass feedstock traits through marker-assisted breeding and biotechnology approaches calls for genomic tools development. Establishment of integrated physical and genetic maps for switchgrass will accelerate mapping of value added traits useful to breeding programs and to isolate important target genes using map based cloning. The reported polyploidy series in switchgrass ranges from diploid (2X = 18 to duodecaploid (12X = 108. Like in other large, repeat-rich plant genomes, this genomic complexity will hinder whole genome sequencing efforts. An extensive physical map providing enough information to resolve the homoeologous genomes would provide the necessary framework for accurate assembly of the switchgrass genome. Results A switchgrass BAC library constructed by partial digestion of nuclear DNA with EcoRI contains 147,456 clones covering the effective genome approximately 10 times based on a genome size of 3.2 Gigabases (~1.6 Gb effective. Restriction digestion and PFGE analysis of 234 randomly chosen BACs indicated that 95% of the clones contained inserts, ranging from 60 to 180 kb with an average of 120 kb. Comparative sequence analysis of two homoeologous genomic regions harboring orthologs of the rice OsBRI1 locus, a low-copy gene encoding a putative protein kinase and associated with biomass, revealed that orthologous clones from homoeologous chromosomes can be unambiguously distinguished from each other and correctly assembled to respective fingerprint contigs. Thus, the data obtained not only provide genomic resources for further analysis of switchgrass genome, but also improve efforts for an accurate genome sequencing strategy. Conclusions The construction of the first switchgrass BAC library and comparative analysis of
Coastal Harbors Modeling Facility
Federal Laboratory Consortium — The Coastal Harbors Modeling Facility is used to aid in the planning of harbor development and in the design and layout of breakwaters, absorbers, etc.. The goal is...
Kim, Jongbum; Kim, Suk Hyun; Hong, Gi Hoon; Suedel, Burton C; Clarke, Joan
2010-01-01
Many years of untreated effluent discharge from residential areas, a shipyard, a marina, and a large fish market resulted in substantial contamination of bottom sediment in Southern Busan Harbor, South Korea. Contaminants in these sediments include heavy metals and organic compounds. Newly introduced regulations for ocean disposal of dredged material in South Korea pose significant challenges, because the previous practice of offshore disposal of contaminated dredged material was no longer possible after August 2008. The South Korean government has mandated that such sediments be assessed in a way that identifies the most appropriate dredged material management alternative, addressing environmental, social, and cost objectives. An approach using multicriteria decision analysis (MCDA) in combination with comparative risk assessment was used as a systematic and transparent framework for prioritizing several dredged sediment management alternatives. We illustrate how MCDA can recognize the multiple goals of contaminated sediment management. Values used in weighting decision criteria were derived from surveys of stakeholders who were sediment management professionals, business owners, or government decision makers. The results of the analysis showed that land reclamation was the preferred alternative among cement-lock, sediment washing, 3 contained aquatic disposal alternatives (one in combination with a hopper dredge), geotextile tubes, solidification, and land reclamation after solidification treatment. Land reclamation was the preferred alternative, which performed well across all MCDA objectives, because of the availability of a near-shore confined disposal facility within a reasonable distance from the dredging area.
Tolkova, Elena; Power, William
2011-06-01
To a tsunami wave, bays and harbors represent oscillatory systems, whose resonance (normal) modes determine the response to tsunami and consequently the potential hazard. The direct way to obtain the resonance modes of a water reservoir is by solving the boundary problem for the eigenfunctions of the linearized shallow-water wave equation. The principal difficulty of posing such a problem for a basin coupled to an ocean is specifying the boundary between the two. The technique developed in this work allows the normal modes of a semi-enclosed water body to be obtained without a-priori restricting the resonator area. The technique utilizes complex Empirical Orthogonal Function analysis of modeled tsunami wave fields. On the examples of Poverty Bay in New Zealand and Monterey Bay in California (United States), we demonstrate that the normal modes can be identified and isolated using the EOFs of a data set comprised of the concatenated time-series collected from different tsunami scenarios in a basin. The analysis of the modeled tsunami wave fields for the normal modes can also answer the question of how likely and under which conditions the different modes are exited, due to feasible natural events.
A theoretical introduction to numerical analysis
Ryaben'kii, Victor S
2006-01-01
PREFACE ACKNOWLEDGMENTS INTRODUCTION Discretization Conditioning Error On Methods of Computation INTERPOLATION OF FUNCTIONS. QUADRATURES ALGEBRAIC INTERPOLATION Existence and Uniqueness of Interpolating Polynomial Classical Piecewise Polynomial Interpolation Smooth Piecewise Polynomial Interpolation (Splines) Interpolation of Functions of Two Variables TRIGONOMETRIC INTERPOLATION Interpolation of Periodic Functions Interpolation of Functions on an Interval. Relation between Algebraic and Trigonometric Interpolation COMPUTATION OF DEFINITE INTEGRALS. QUADRATURES Trapezoidal Rule, Simpson's Formula, and the Like Quadrature Formulae with No Saturation. Gaussian Quadratures Improper Integrals. Combination of Numerical and Analytical Methods Multiple Integrals SYSTEMS OF SCALAR EQUATIONS SYSTEMS OF LINEAR ALGEBRAIC EQUATIONS: DIRECT METHODS Different Forms of Consistent Linear Systems Linear Spaces, Norms, and Operators Conditioning of Linear Systems Gaussian Elimination and Its Tri-Diag...
Development of numerical procedures for analysis of complex structures
Gupta, K. K.
1984-01-01
The paper is concerned with the development of novel numerical procedures for the solution of static, stability, free vibration and dynamic response analysis of large, complex practical structures. Thus, details of numerical algorithms evolved for dynamic analysis of usual non-rotating and also rotating structures as well as finite dynamic elements are presented in the paper. Furthermore, the article provides some description of a general-purpose computer program STARS specifically developed for efficient analysis of complex practical structures.
Research in applied mathematics, numerical analysis, and computer science
1984-01-01
Research conducted at the Institute for Computer Applications in Science and Engineering (ICASE) in applied mathematics, numerical analysis, and computer science is summarized and abstracts of published reports are presented. The major categories of the ICASE research program are: (1) numerical methods, with particular emphasis on the development and analysis of basic numerical algorithms; (2) control and parameter identification; (3) computational problems in engineering and the physical sciences, particularly fluid dynamics, acoustics, and structural analysis; and (4) computer systems and software, especially vector and parallel computers.
Elements of Constitutive Modelling and Numerical Analysis of Frictional Soils
Jakobsen, Kim Parsberg
This thesis deals with elements of elasto-plastic constitutive modelling and numerical analysis of frictional soils. The thesis is based on a number of scientific papers and reports in which central characteristics of soil behaviour and applied numerical techniques are considered. The development...
Numerical analysis for finite Fresnel transform
Aoyagi, Tomohiro; Ohtsubo, Kouichi; Aoyagi, Nobuo
2016-10-01
The Fresnel transform is a bounded, linear, additive, and unitary operator in Hilbert space and is applied to many applications. In this study, a sampling theorem for a Fresnel transform pair in polar coordinate systems is derived. According to the sampling theorem, any function in the complex plane can be expressed by taking the products of the values of a function and sampling function systems. Sampling function systems are constituted by Bessel functions and their zeros. By computer simulations, we consider the application of the sampling theorem to the problem of approximating a function to demonstrate its validity. Our approximating function is a circularly symmetric function which is defined in the complex plane. Counting the number of sampling points requires the calculation of the zeros of Bessel functions, which are calculated by an approximation formula and numerical tables. Therefore, our sampling points are nonuniform. The number of sampling points, the normalized mean square error between the original function and its approximation function and phases are calculated and the relationship between them is revealed.
Dongarra, J. (Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science Oak Ridge National Lab., TN (United States)); Rosener, B. (Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science)
1991-12-01
This report describes a facility called NA-NET created to allow numerical analysts (na) an easy method of communicating with one another. The main advantage of the NA-NET is uniformity of addressing. All mail is addressed to the Internet host na-net.ornl.gov'' at Oak Ridge National Laboratory. Hence, members of the NA-NET do not need to remember complicated addresses or even where a member is currently located. As long as moving members change their e-mail address in the NA-NET everything works smoothly. The NA-NET system is currently located at Oak Ridge National Laboratory. It is running on the same machine that serves netlib. Netlib is a separate facility that distributes mathematical software via electronic mail. For more information on netlib consult, or send the one-line message send index'' to netlib{at}ornl.gov. The following report describes the current NA-NET system from both a user's perspective and from an implementation perspective. Currently, there are over 2100 members in the NA-NET. An average of 110 mail messages pass through this facility daily.
Dongarra, J. [Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science]|[Oak Ridge National Lab., TN (United States); Rosener, B. [Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science
1991-12-01
This report describes a facility called NA-NET created to allow numerical analysts (na) an easy method of communicating with one another. The main advantage of the NA-NET is uniformity of addressing. All mail is addressed to the Internet host ``na-net.ornl.gov`` at Oak Ridge National Laboratory. Hence, members of the NA-NET do not need to remember complicated addresses or even where a member is currently located. As long as moving members change their e-mail address in the NA-NET everything works smoothly. The NA-NET system is currently located at Oak Ridge National Laboratory. It is running on the same machine that serves netlib. Netlib is a separate facility that distributes mathematical software via electronic mail. For more information on netlib consult, or send the one-line message ``send index`` to netlib{at}ornl.gov. The following report describes the current NA-NET system from both a user`s perspective and from an implementation perspective. Currently, there are over 2100 members in the NA-NET. An average of 110 mail messages pass through this facility daily.
Numerical Analysis of Magnetic Fluid Sealing Performance
无
2006-01-01
The sealing performance of magnetic fluid is related to the magnetic fluid itself. Many factors can influence the magnetic field and the seal pressure differences of magnetic fluid seals, such as the sealing gap, the shaft eccentricity, the shaft diameter, the volume of the magnetic fluid and the centrifugal force. These factors are analyzed by numerical computation . When the seal material and structure are the same, the seal pressure difference is directly proportional to the magnetic field intensity and the saturation magnetization of the magnetic fluid. The sealing performance of the magnetic fluid will reduce with the increase of the sealing gap and shaft eccentricity. The sealing performance will increase with the volume of the magnetic fluid and decrease with the increase of the shaft diameter taking gravity into account. The increase of the shaft diameter is the same as the reduction of the volume of the magnetic fluid. The magnetic fluid cross-section can change because of the centrifugal force. Some improvements can reduce the influence of the centrifugal force. The centrifugal force can be utilized to improve the sealing performance.
Liu, Mao-Sen; Li, Hui-Chun; Chang, You-Min; Wu, Min-Tze; Chen, Long-Fang Oliver
2011-09-01
Our previous study revealed a cytokinin-related retardation of post-harvest floret yellowing in transgenic broccoli (Brassica oleracea var. italica) that harbored the bacterial isopentenyltransferase (ipt) gene. We aimed to investigate the underlining mechanism of this delayed post-harvest senescence. We used 2D electrophoresis and liquid chromatography-electrospray ionization-mass spectrometry/mass spectrometry for a proteomics analysis of heads of ipt-transgenic and non-transgenic inbred lines of broccoli at harvest and after four days post-harvest storage. At harvest, we found an accumulation of stress-responsive proteins involved in maintenance of protein folding (putative protein disulfide isomerase, peptidyl-prolyl cis-trans isomerase and chaperonins), scavenging of reactive oxygen species (Mn superoxide dismutase), and stress protection [myrosinase-binding protein, jasmonate inducible protein, dynamin-like protein, NADH dehydrogenase (ubiquinone) Fe-S protein 1 and stress-inducible tetratricopeptide repeat-containing protein]. After four days' post-harvest storage of non-transgenic broccoli florets, the levels of proteins involved in protein folding and carbon fixation were decreased, which indicates cellular degradation and a change in metabolism toward senescence. In addition, staining for antioxidant enzyme activity of non-transgenic plants after post-harvest storage revealed a marked decrease in activity of Fe-superoxide dismutase and ascorbate peroxidase. Thus, the accumulation of stress-responsive proteins and antioxidant enzyme activity in ipt-transgenic broccoli are most likely associated with retardation of post-harvest senescence.
Using R for numerical analysis in science and engineering
Bloomfield, Victor A
2014-01-01
Instead of presenting the standard theoretical treatments that underlie the various numerical methods used by scientists and engineers, Using R for Numerical Analysis in Science and Engineering shows how to use R and its add-on packages to obtain numerical solutions to the complex mathematical problems commonly faced by scientists and engineers. This practical guide to the capabilities of R demonstrates Monte Carlo, stochastic, deterministic, and other numerical methods through an abundance of worked examples and code, covering the solution of systems of linear algebraic equations and nonlinea
Mathematical theory of compressible viscous fluids analysis and numerics
Feireisl, Eduard; Pokorný, Milan
2016-01-01
This book offers an essential introduction to the mathematical theory of compressible viscous fluids. The main goal is to present analytical methods from the perspective of their numerical applications. Accordingly, we introduce the principal theoretical tools needed to handle well-posedness of the underlying Navier-Stokes system, study the problems of sequential stability, and, lastly, construct solutions by means of an implicit numerical scheme. Offering a unique contribution – by exploring in detail the “synergy” of analytical and numerical methods – the book offers a valuable resource for graduate students in mathematics and researchers working in mathematical fluid mechanics. Mathematical fluid mechanics concerns problems that are closely connected to real-world applications and is also an important part of the theory of partial differential equations and numerical analysis in general. This book highlights the fact that numerical and mathematical analysis are not two separate fields of mathematic...
Numerical methods design, analysis, and computer implementation of algorithms
Greenbaum, Anne
2012-01-01
Numerical Methods provides a clear and concise exploration of standard numerical analysis topics, as well as nontraditional ones, including mathematical modeling, Monte Carlo methods, Markov chains, and fractals. Filled with appealing examples that will motivate students, the textbook considers modern application areas, such as information retrieval and animation, and classical topics from physics and engineering. Exercises use MATLAB and promote understanding of computational results. The book gives instructors the flexibility to emphasize different aspects--design, analysis, or c
Numerical bifurcation analysis of immunological models with time delays
Luzyanina, Tatyana; Roose, Dirk; Bocharov, Gennady
2005-12-01
In recent years, a large number of mathematical models that are described by delay differential equations (DDEs) have appeared in the life sciences. To analyze the models' dynamics, numerical methods are necessary, since analytical studies can only give limited results. In turn, the availability of efficient numerical methods and software packages encourages the use of time delays in mathematical modelling, which may lead to more realistic models. We outline recently developed numerical methods for bifurcation analysis of DDEs and illustrate the use of these methods in the analysis of a mathematical model of human hepatitis B virus infection.
Numerical analysis of complex fluid-flow systems
Holland, R. L.
1980-01-01
Very flexible computer-assisted numerical analysis is used to solve dynamic fluid-flow equations characterizing computer-controlled heat dissipation system developed for Space lab. Losses caused by bends, ties, fittings, valves, and like are easily included, and analysis can solve both steady-state and transient cases. It can also interact with parallel thermal analysis.
A numerical comparison of sensitivity analysis techniques
Hamby, D.M.
1993-12-31
Engineering and scientific phenomena are often studied with the aid of mathematical models designed to simulate complex physical processes. In the nuclear industry, modeling the movement and consequence of radioactive pollutants is extremely important for environmental protection and facility control. One of the steps in model development is the determination of the parameters most influential on model results. A {open_quotes}sensitivity analysis{close_quotes} of these parameters is not only critical to model validation but also serves to guide future research. A previous manuscript (Hamby) detailed many of the available methods for conducting sensitivity analyses. The current paper is a comparative assessment of several methods for estimating relative parameter sensitivity. Method practicality is based on calculational ease and usefulness of the results. It is the intent of this report to demonstrate calculational rigor and to compare parameter sensitivity rankings resulting from various sensitivity analysis techniques. An atmospheric tritium dosimetry model (Hamby) is used here as an example, but the techniques described can be applied to many different modeling problems. Other investigators (Rose; Dalrymple and Broyd) present comparisons of sensitivity analyses methodologies, but none as comprehensive as the current work.
Numerical analysis of human dental occlusal contact
Bastos, F. S.; Las Casas, E. B.; Godoy, G. C. D.; Meireles, A. B.
2010-06-01
The purpose of this study was to obtain real contact areas, forces, and pressures acting on human dental enamel as a function of the nominal pressure during dental occlusal contact. The described development consisted of three steps: characterization of the surface roughness by 3D contact profilometry test, finite element analysis of micro responses for each pair of main asperities in contact, and homogenization of macro responses using an assumed probability density function. The inelastic deformation of enamel was considered, adjusting the stress-strain relationship of sound enamel to that obtained from instrumented indentation tests conducted with spherical tip. A mechanical part of the static friction coefficient was estimated as the ratio between tangential and normal components of the overall resistive force, resulting in μd = 0.057. Less than 1% of contact pairs reached the yield stress of enamel, indicating that the occlusal contact is essentially elastic. The micro-models indicated an average hardness of 6.25GPa, and the homogenized result for macroscopic interface was around 9GPa. Further refinements of the methodology and verification using experimental data can provide a better understanding of processes related to contact, friction and wear of human tooth enamel.
Meng XUN; Si-hai ZHAO; Chun-xia CAO; Juan SONG; Ming-ming SHAO; Yong-lie CHU
2008-01-01
Aim: The present study examined the differential expression of proteins in HuH-7 cells and HUH-7 cells harboring in vitro-transcribed full-length hepatitis C virus 1b RNA (HuH-7-HCV), and elucidated the cellular responses to HCV replication. Methods: The protein profiles of matched pairs of HuH-7-HCV cells and HUH-7 mock cells were analyzed by 2-D electrophoresis (2DE). Solubilized proteins were separated in the first dimension by isoelectric focusing, and by 12.5% SDS-PAGE in the second dimension. The differential protein expression was analyzed by use of image analysis software to identify candidates for HCV infection-associated proteins. Results: In total, 29 protein spots showed increases and 25 protein spots showed decreases in signal in HuH-7-HCV cell 2DE profiles as compared with HuH-7 mock cells. In the next step, the 10 spots showing the greatest in-crease and the 10 spots showing the greatest decrease were excised from gels and the proteins present were identified by Matrix-Assisted Laser Desorption/Ioniza-tion Time of Flight Mass Spectrometer (MALDI-TOF MS) or MALDI-TOF/TOF MS. In total, 13 proteins were identified successfully. The potential significance of the differential expression due to HCV replication was discussed. Conclusion: Our study identifies changes in the proteome of HuH-7 cells in the presence of HCV replication and yields information of the mechanism of HCV pathogenesis. These results will be useful for the identification of HCV infection-associated proteins that could be molecular targets for treatment.
Hamming, R W
1965-04-23
I hope I have shown not that mathematicians are incompetent or wrong, but why I believe that their interests, tastes, and objectives are frequently different from those of practicing numerical analysts, and why activity in numerical analysis should be evaluated by its own standards and not by those of pure mathematics. I hope I have also shown you that much of the "art form" of mathematics consists of delicate, "noise-free" results, while many areas of applied mathematics, especially numerical analysis, are dominated by noise. Again, in computing the process is fundamental, and rigorous mathematical proofs are often meaningless in computing situations. Finally, in numerical analysis, as in engineering, choosing the right model is more important than choosing the model with the elegant mathematics.
Numerical Analysis of Conductor Galloping Limitation by Oscillation Frequency Detuning
I. I. Serguey
2009-01-01
Full Text Available A numerical method has been developed for calculation of conductor oscillations at the moment of galloping that takes account of pendulum oscillation dampers in the form of eccentric loads. The method is recommended for a numerical analysis of various schemes pertaining to arrangement of horizontal pendulums in the span and their parameters including angles of their initial setting. The obtained results can be used for designing and operation of aerial power lines.
Interval analysis for Certified Numerical Solution of Problems in Robotics
Merlet, Jean-Pierre
2009-01-01
International audience; Interval analysis is a relatively new mathematical tool that allows one to deal with problems that may have to be solved numerically with a computer. Examples of such problems are system solving and global optimization but numerous other problems may be addressed as well. This approach has the following general advantages: 1 it allows to find solutions of a problem only within some finite domain which make sense as soon as the unknowns in the problem are physical param...
Numerical Analysis of Dynamic Direct Tension and Direct Compression Tests
1993-01-01
material model employed in the nonlinear analysis is a hypoelastic model based on a uniaxial stress-strain relation (Figure 18) that is generalized to...rates. Both an elastic and inelastic concrete material model were employed in all numerical analyses. The modes of failure predicted by the numerical... models ; (2) augmenting the system by adding other typical scenarios, with the ultimate goal of expanding it into a general task-oriented system/shell; and
Numerical Analysis of Shock Induced Separation Delay by Air Humidity
Piotr DOERFFER; Slawomir DYKAS
2005-01-01
@@ In this paper numerical calculations of the dry and humid air flows in the nozzle are presented. The dry air flow (adiabatic flow) and the humid air flow (flow with homogeneous condensation, diabatic flow) are modeled with the use of Reynolds Averaged Navier-Stokes (RANS) equations. The comparison of these two types of flow is carried out. The influence of the air humidity on the shock wave location and its interaction with the boundary layer is examined. Obtained numerical results present a first numerical approach of the condensation and evaporation process in transonic flow of humid air. The phenomena considered here are very complex and complicated and need further in-depth numerical analysis.
Shape sensitivity analysis in numerical modelling of solidification
E. Majchrzak
2007-12-01
Full Text Available The methods of sensitivity analysis constitute a very effective tool on the stage of numerical modelling of casting solidification. It is possible, among others, to rebuilt the basic numerical solution on the solution concerning the others disturbed values of physical and geometrical parameters of the process. In this paper the problem of shape sensitivity analysis is discussed. The non-homogeneous casting-mould domain is considered and the perturbation of the solidification process due to the changes of geometrical dimensions is analyzed. From the mathematical point of view the sensitivity model is rather complex but its solution gives the interesting information concerning the mutual connections between the kinetics of casting solidification and its basic dimensions. In the final part of the paper the example of computations is shown. On the stage of numerical realization the finite difference method has been applied.
Partial differential equations modeling, analysis and numerical approximation
Le Dret, Hervé
2016-01-01
This book is devoted to the study of partial differential equation problems both from the theoretical and numerical points of view. After presenting modeling aspects, it develops the theoretical analysis of partial differential equation problems for the three main classes of partial differential equations: elliptic, parabolic and hyperbolic. Several numerical approximation methods adapted to each of these examples are analyzed: finite difference, finite element and finite volumes methods, and they are illustrated using numerical simulation results. Although parts of the book are accessible to Bachelor students in mathematics or engineering, it is primarily aimed at Masters students in applied mathematics or computational engineering. The emphasis is on mathematical detail and rigor for the analysis of both continuous and discrete problems. .
Investigating Convergence Patterns for Numerical Methods Using Data Analysis
Gordon, Sheldon P.
2013-01-01
The article investigates the patterns that arise in the convergence of numerical methods, particularly those in the errors involved in successive iterations, using data analysis and curve fitting methods. In particular, the results obtained are used to convey a deeper level of understanding of the concepts of linear, quadratic, and cubic…
Numerical analysis of electro-osmosis consolidation: a case study
Yuan, J.; Hicks, M.A.
2015-01-01
A numerical model for the design and analysis of electro-osmosis consolidation in soft clay is used to study a well-documented full-scale field test. The large-strain model, which considers coupled electro-osmosis flow, hydraulic flow and electric density flow in a deformable elasto-plastic porous m
Scilab and Maxima Environment: Towards Free Software in Numerical Analysis
Mora, Angel; Galan, Jose Luis; Aguilera, Gabriel; Fernandez, Alvaro; Merida, Enrique; Rodriguez, Pedro
2010-01-01
In this work we will present the ScilabUMA environment we have developed as an alternative to Matlab. This environment connects Scilab (for numerical analysis) and Maxima (for symbolic computations). Furthermore, the developed interface is, in our opinion at least, as powerful as the interface of Matlab. (Contains 3 figures.)
Assessment of Available Numerical Tools for Dynamic Mooring Analysis
Thomsen, Jonas Bjerg; Eskilsson, Claes; Ferri, Francesco
This report covers a preliminary assessment of available numerical tools to be used in upcoming full dynamic analysis of the mooring systems assessed in the project _Mooring Solutions for Large Wave Energy Converters_. The assessments tends to cover potential candidate software and subsequently c...
Numerical equilibrium analysis for structured consumer resource models
de Roos, A.M.; Diekmann, O.; Getto, P.; Kirkilionis, M.A.
2010-01-01
In this paper, we present methods for a numerical equilibrium and stability analysis for models of a size structured population competing for an unstructured re- source. We concentrate on cases where two model parameters are free, and thus existence boundaries for equilibria and stability boundaries
Investigating Convergence Patterns for Numerical Methods Using Data Analysis
Gordon, Sheldon P.
2013-01-01
The article investigates the patterns that arise in the convergence of numerical methods, particularly those in the errors involved in successive iterations, using data analysis and curve fitting methods. In particular, the results obtained are used to convey a deeper level of understanding of the concepts of linear, quadratic, and cubic…
Frenod, Emmanuel
2013-01-01
In this note, a classification of Homogenization-Based Numerical Methods and (in particular) of Numerical Methods that are based on the Two-Scale Convergence is done. In this classification stand: Direct Homogenization-Based Numerical Methods; H-Measure-Based Numerical Methods; Two-Scale Numerical Methods and TSAPS: Two-Scale Asymptotic Preserving Schemes.
Numerical and Analytical Analysis of Elastic Rotor Natural Frequency
Adis J. Muminovic
2014-11-01
Full Text Available In this paper simulation model which enables quick analysis of elastic rotor natural frequency modes is developed using Matlab. This simulation model enables users to get dependency diagram of natural frequency in relation to diameter and length of the rotor,density of the material or modulus of elasticity. Testing of the model is done using numerical analysis in SolidWorks software.
NUMERICAL ANALYSIS OF A FEM FOR A TRANSIENT VISCOELASTIC FLOW
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).
Introduction to Numerical Computation - analysis and Matlab illustrations
Elden, Lars; Wittmeyer-Koch, Linde; Nielsen, Hans Bruun
their properties. The book describes and analyses numerical methods for error analysis, differentiation, integration, interpolation and approximation, and the solution of nonlinear equations, linear systems of algebraic equations and systems of ordinary differential equations. Principles and algorithms......In a modern programming environment like eg MATLAB it is possible by simple commands to perform advanced calculations on a personal computer. In order to use such a powerful tool efiiciently it is necessary to have an overview of available numerical methods and algorithms and to know about...
Numeric computation and statistical data analysis on the Java platform
Chekanov, Sergei V
2016-01-01
Numerical computation, knowledge discovery and statistical data analysis integrated with powerful 2D and 3D graphics for visualization are the key topics of this book. The Python code examples powered by the Java platform can easily be transformed to other programming languages, such as Java, Groovy, Ruby and BeanShell. This book equips the reader with a computational platform which, unlike other statistical programs, is not limited by a single programming language. The author focuses on practical programming aspects and covers a broad range of topics, from basic introduction to the Python language on the Java platform (Jython), to descriptive statistics, symbolic calculations, neural networks, non-linear regression analysis and many other data-mining topics. He discusses how to find regularities in real-world data, how to classify data, and how to process data for knowledge discoveries. The code snippets are so short that they easily fit into single pages. Numeric Computation and Statistical Data Analysis ...
Numerical analysis of cavitation within slanted axial-flow pump
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.
Numerical analysis on pool boiling using user defined function
Ryu, Sung Uk; Jeon, Byong Guk; Kim, Seok; Euh, Dong-Jin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2015-10-15
PAFS (passive auxiliary feedwater system) adopted in the APR+ (Advanced Power Reactor Plus) of Korea is one such application. When PAFS is activated with an actuation signal, steam from the steam generator passes through heat exchanger tubes submerged in a water tank of the PAFS. Outside these heat exchanger tubes, nucleate boiling phenomena appears. In the present work, a numerical study is reported on three-dimensional transient state pool boiling of water having an immersed heat source. The velocity vector fields during the decrease in the water level are numerically investigated in a pool, and the accuracy of the results is checked by comparing the experimental results conducted using the PIV techniques by Kim et al. These numerical results can be used as basic research data for an analysis and prediction of the natural circulation phenomena in the cooling tank of the passive safety system in a nuclear power plant.
Numerical simulation analysis of Guixi copper flash smelting furnace
无
2002-01-01
A numerical simulation analysis for reactions of chalcopyrite and pyrite particles coupled with momentum, heat and mass transfer between the particle and gas in a flash smelting furnace is presented. In the simulation, the equations governing the gas flow are solved numerically by Eular method. The particle phase is introduced into the gas flow by the particle-source-in-cell technique (PSIC). Predictions including the fluid flow field, temperature field, concentration field of gas phase and the tracks of particles have been obtained by the numerical simulation. The visualized results show that the reaction of sulfide particles is almost completed in the upper zone of the shaft within 1.5 m far from the central jet distributor (CJD) type concentrate burner. The simulation results are in good agreement with data obtained from a series of experiments and tests in the plant and the error is less than 2%.
Aylott, Benjamin; Boggs, William D; Boyle, Michael; Brady, Patrick R; Brown, Duncan A; Brügmann, Bernd; Buchman, Luisa T; Buonanno, Alessandra; Cadonati, Laura; Camp, Jordan; Campanelli, Manuela; Centrella, Joan; Chatterji, Shourov; Christensen, Nelson; Chu, Tony; Diener, Peter; Dorband, Nils; Etienne, Zachariah B; Faber, Joshua; Fairhurst, Stephen; Farr, Benjamin; Fischetti, Sebastian; Guidi, Gianluca; Goggin, Lisa M; Hannam, Mark; Herrmann, Frank; Hinder, Ian; Husa, Sascha; Kalogera, Vicky; Keppel, Drew; Kidder, Lawrence E; Kelly, Bernard J; Krishnan, Badri; Laguna, Pablo; Lousto, Carlos O; Mandel, Ilya; Marronetti, Pedro; Matzner, Richard; McWilliams, Sean T; Matthews, Keith D; Mercer, R Adam; Mohapatra, Satyanarayan R P; Mroué, Abdul H; Nakano, Hiroyuki; Ochsner, Evan; Pan, Yi; Pekowsky, Larne; Pfeiffer, Harald P; Pollney, Denis; Pretorius, Frans; Raymond, Vivien; Reisswig, Christian; Rezzolla, Luciano; Rinne, Oliver; Robinson, Craig; Röver, Christian; Santamaría, Lucía; Sathyaprakash, Bangalore; Scheel, Mark A; Schnetter, Erik; Seiler, Jennifer; Shapiro, Stuart L; Shoemaker, Deirdre; Sperhake, Ulrich; Stroeer, Alexander; Sturani, Riccardo; Tichy, Wolfgang; Liu, Yuk Tung; van der Sluys, Marc; van Meter, James R; Vaulin, Ruslan; Vecchio, Alberto; Veitch, John; Viceré, Andrea; Whelan, John T; Zlochower, Yosef
2009-01-01
The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational-wave data analysis communities. The purpose of NINJA is to study the sensitivity of existing gravitational-wave search algorithms using numerically generated waveforms and to foster closer collaboration between the numerical relativity and data analysis communities. We describe the results of the first NINJA analysis which focused on gravitational waveforms from binary black hole coalescence. Ten numerical relativity groups contributed numerical data which were used to generate a set of gravitational-wave signals. These signals were injected into a simulated data set, designed to mimic the response of the Initial LIGO and Virgo gravitational-wave detectors. Nine groups analysed this data using search and parameter-estimation pipelines. Matched filter algorithms, un-modelled-burst searches and Bayesian parameter-estimation and model-selection algorithms were applied to the da...
Bolean, Maytê; Borin, Ivana A; Simão, Ana M S
2017-01-01
Atomic force microscopy (AFM) is one of the most commonly used scanning probe microscopy techniques for nanoscale imaging and characterization of lipid-based particles. However, obtaining images of such particles using AFM is still a challenge. The present study extends the capabilities of AFM...... fluidity. Surface protrusions were measurable in TNAP-proteoliposomes but barely detectable in AnxA5-proteoliposomes. More complex surface structures were observed for proteoliposomes harboring both TNAP and AnxA5 concomitantly, resulting in a lower affinity for type II collagen fibers compared...
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.
NUMERICAL THERMAL ANALYSIS OF A CAR BRAKING SYSTEM
Patryk Różyło
2017-06-01
Full Text Available The study involved performing a numerical thermal analysis of selected components in a car braking system. The primary goal of the study was to determine the regions which are the most susceptible to variations in temperature, and to determine the degree of thermal impact upon them. The analysis was performed using the Abaqus environment. The examined components of the braking system were made of materials reflecting the mechanical properties of the real subassemblies. The FEM analysis enabled determination of the distribution of temperature in the system with respect to the properties of the investigated materials and applied boundary conditions.
Pearl Harbor Biological Survey
1974-08-30
Distribution of Porifera (Wet Weight in Grams) Collected in Piling Samples from Pearl Harbor, Oahu 2.4-26 2.4-7. Syllidae 2.4-28 2.4-8. Cirratulidae...COLLECTED FROM PEARL HARBOR m .-. Sped es/Group Porifera Demospongiae Cnidaria Hydrozoa Hydrdda Anthozoa Actlnarla Stolchactlnldae Radianthus...and abundance data for 113 taxa (species, genera and higher taxa) are provided in Table 2.4-4. Wet weights are listed for all sponges ( porifera ). The
Numerical stability analysis in respiratory control system models
Laszlo E. Kollar
2005-04-01
Full Text Available Stability of the unique equilibrium in two mathematical models (based on chemical balance dynamics of human respiration is examined using numerical methods. Due to the transport delays in the respiratory control system these models are governed by delay differential equations. First, a simplified two-state model with one delay is considered, then a five-state model with four delays (where the application of numerical methods is essential is investigated. In particular, software is developed to perform linearized stability analysis and simulations of the model equations. Furthermore, the Matlab package DDE-BIFTOOL v.~2.00 is employed to carry out numerical bifurcation analysis. Our main goal is to study the effects of transport delays on the stability of the model equations. Critical values of the transport delays (i.e., where Hopf bifurcations occur are determined, and stable periodic solutions are found as the delays pass their critical values. The numerical findings are in good agreement with analytic results obtained earlier for the two-state model.
Numerical analysis of the human nostril by the Fourier series.
Goto, M; Katsuki, T
1990-02-01
Fourier series has been applied in a numerical analysis of the human nostril morphology. The relationship between the nostril form and the Fourier coefficients was examined: the constant affected the size, the first term determined the roundness, and the second term determined the flatness of the morphology. The inclination of the apse line was calculated from the phase of the second term. Ninety-five standardized nostril photographs were analyzed by Fourier series: 48 of adult Japanese females and 47 of German females. The German nostril was larger in size, flatter in shape, and the apse line closer to the sagittal plane than the Japanese counterpart. As a clinical application of nostril digitization, pre- and post-operative cleft lip noses were analyzed. Fourier analysis has proved to be useful in a numerical evaluation of morphological differences of, and post-operative changes made to, the nostril.
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.
Numerical Analysis of Modal Instability Onset in Fiber Amplifiers
2014-03-11
Evolution of the logarithmic frequency spectrum of the off-center optical intensity probe along the length of the co-pumped amplifier for the case of...Evolution of the logarithmic frequency spectrum of the off-center optical intensity probe along the length of the counter-pumped amplifier for the...ABSTRACT 16. SECURITY CLASSIFICATION OF: Numerical analysis of the onset of modal instability in fiber amplifiers is presented. Specifically calculations
Clustered Numerical Data Analysis Using Markov Lie Monoid Based Networks
Johnson, Joseph
2016-03-01
We have designed and build an optimal numerical standardization algorithm that links numerical values with their associated units, error level, and defining metadata thus supporting automated data exchange and new levels of artificial intelligence (AI). The software manages all dimensional and error analysis and computational tracing. Tables of entities verses properties of these generalized numbers (called ``metanumbers'') support a transformation of each table into a network among the entities and another network among their properties where the network connection matrix is based upon a proximity metric between the two items. We previously proved that every network is isomorphic to the Lie algebra that generates continuous Markov transformations. We have also shown that the eigenvectors of these Markov matrices provide an agnostic clustering of the underlying patterns. We will present this methodology and show how our new work on conversion of scientific numerical data through this process can reveal underlying information clusters ordered by the eigenvalues. We will also show how the linking of clusters from different tables can be used to form a ``supernet'' of all numerical information supporting new initiatives in AI.
Numerical analysis on thermal drilling of aluminum metal matrix composite
Hynes, N. Rajesh Jesudoss; Maheshwaran, M. V.
2016-05-01
The work-material deformation is very large and both the tool and workpiece temperatures are high in thermal drilling. Modeling is a necessary tool to understand the material flow, temperatures, stress, and strains, which are difficult to measure experimentally during thermal drilling. The numerical analysis of thermal drilling process of aluminum metal matrix composite has been done in the present work. In this analysis the heat flux of different stages is calculated. The calculated heat flux is applied on the surface of work piece and thermal distribution is predicted in different stages during the thermal drilling process.
Numerical analysis of modified Central Solenoid insert design
Khodak, Andrei, E-mail: akhodak@pppl.gov [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Martovetsky, Nicolai; Smirnov, Aleksandre [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Titus, Peter [Princeton Plasma Physics Laboratory, Princeton, NJ (United States)
2015-10-15
Highlights: • Modified design of coil for testing ITER superconducting cable is presented. • Numerical analysis allowed design verification. • Three-dimensional current sharing temperature distributions are obtained from the results. - Abstract: The United States ITER Project Office (USIPO) is responsible for fabrication of the Central Solenoid (CS) for ITER project. The ITER machine is currently under construction by seven parties in Cadarache, France. The CS Insert (CSI) project should provide a verification of the conductor performance in relevant conditions of temperature, field, currents and mechanical strain. The US IPO designed the CSI that will be tested at the Central Solenoid Model Coil (CSMC) Test Facility at JAEA, Naka. To validate the modified design three-dimensional numerical simulations were performed using coupled solver for simultaneous structural, thermal and electromagnetic analysis. Thermal and electromagnetic simulations supported structural calculations providing necessary loads and strains. According to current analysis design of the modified coil satisfies ITER magnet structural design criteria for the following conditions: (1) room temperature, no current, (2) temperature 4 K, no current, (3) temperature 4 K, current 60 kA direct charge, and (4) temperature 4 K, current 60 kA reverse charge. Fatigue life assessment analysis is performed for the alternating conditions of: temperature 4 K, no current, and temperature 4 K, current 45 kA direct charge. Results of fatigue analysis show that parts of the coil assembly can be qualified for up to 1 million cycles. Distributions of the Current Sharing Temperature (TCS) in the superconductor were obtained from numerical results using parameterization of the critical surface in the form similar to that proposed for ITER. Special ADPL scripts were developed for ANSYS allowing one-dimensional representation of TCS along the cable, as well as three-dimensional fields of TCS in superconductor
Numerical Ergonomics Analysis in Operation Environment of CNC Machine
Wong, S. F.; Yang, Z. X.
2010-05-01
The performance of operator will be affected by different operation environments [1]. Moreover, poor operation environment may cause health problems of the operator [2]. Physical and psychological considerations are two main factors that will affect the performance of operator under different conditions of operation environment. In this paper, applying scientific and systematic methods find out the pivot elements in the field of physical and psychological factors. There are five main factors including light, temperature, noise, air flow and space that are analyzed. A numerical ergonomics model has been built up regarding the analysis results which can support to advance the design of operation environment. Moreover, the output of numerical ergonomic model can provide the safe, comfortable, more productive conditions for the operator.
Numerical analysis of anisotropic diffusion effect on ICF hydrodynamic instabilities
Olazabal-Loumé M.
2013-11-01
Full Text Available The effect of anisotropic diffusion on hydrodynamic instabilities in the context of Inertial Confinement Fusion (ICF flows is numerically assessed. This anisotropy occurs in indirect-drive when laminated ablators are used to modify the lateral transport [1,2]. In direct-drive, non-local transport mechanisms and magnetic fields may modify the lateral conduction [3]. In this work, numerical simulations obtained with the code PERLE [4], dedicated to linear stability analysis, are compared with previous theoretical results [5]. In these approaches, the diffusion anisotropy can be controlled by a characteristic coefficient which enables a comprehensive study. This work provides new results on the ablative Rayleigh-Taylor (RT, ablative Richtmyer-Meshkov (RM and Darrieus-Landau (DL instabilities.
Numerical analysis of ossicular chain lesion of human ear
Yingxi Liu; Sheng Li; Xiuzhen Sun
2009-01-01
Lesion of ossicular chain is a common ear disease impairing the sense of hearing. A comprehensive numerical model of human ear can provide better understanding of sound transmission. In this study, we propose a three-dimensional finite element model of human ear that incorporates the canal, tympanic membrane, ossicular bones,middle ear suspensory ligaments/muscles, middle ear cavity and inner ear fluid. Numerical analysis is conducted and employed to predict the effects of middle ear cavity, malleus handle defect, hypoplasia of the long process of incus,and stapedial crus defect on sound transmission. The present finite element model is shown to be reasonable in predicting the ossicular mechanics of human ear.
Application of numerical analysis to jet engine combustor design
To, H. (Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan))
1991-04-01
The design and development process of jet engine combustors in Ishikawajima-Harima Heavy Industries Co., Ltd. was presented which is featured by iterated numerical analyses in earlier stages of design. The analytical methods used, models applied and features were given together with verification results of numerical analyses of a velocity profile in a dump diffuser, flow and temperature distribution in a combustion liner, and liner skin temperature distribution. As examples in design and development of an airblast fuel injector type high temperature combustor, analytical results of the followings were given: flows through a diffuser, flows through a combustion liner, flows through liner cooling slots and liner skin temperature distribution. In addition, results of three-dimensional flow analysis were given in terms of optimization of design parameters for a jet-swirl combustor and calculation of a centrifugal force for a jet-swirl combustor liner as examples. 6 refs., 18 figs., 1 tab.
A numerical approach for the analysis of deformable journal bearings
D. Benasciutti
2012-07-01
Full Text Available This paper presents a numerical approach for the analysis of hydrodynamic radial journal bearings. The effect of shaft and housing elastic deformation on pressure distribution within oil film is investigated. An iterative algorithm that couples Reynolds equation with a plane finite elements structural model is solved. Temperature and pressure effects on viscosity are also included with the Vogel-Barus model. The deformed lubrication gap and the overall stress state were calculated. Numerical results are presented with reference to a typical journal bearing configuration at two different inlet oil temperatures. Obtained results show the great influence of elastic deformation of bearing components on oil pressure distribution, compared with results for ideally rigid components obtained by Raimondi and Boyd solution.
Buckling analysis of composite cylindrical shell using numerical analysis method
Jung, Hae Young; Bae, Won Byung [Pusan Nat' l Univ., Busan (Korea, Republic of); Cho, Jong Rae [Korea Maritime Univ., Busan (Korea, Republic of); Lee, Woo Hyung [Underwater Vehicle Research Center, Busan (Korea, Republic of)
2012-01-15
The objective of this paper is to predict the buckling pressure of a composite cylindrical shell using buckling formulas (ASME 2007, NASA SP 8007) and finite element analysis. The model in this study uses a stacking angle of [0/90]12t and USN 125 composite material. All specimens were made using a prepreg method. First, finite element analysis was conducted, and the results were verified through comparison with the hydrostatic pressure bucking experiment results. Second, the values obtained from the buckling formula and the buckling pressure values obtained from the finite element analysis were compared as the stacking angle was changed in 5 .deg. increments from 20 .deg. to 90 .deg. The linear and nonlinear results of the finite element analysis were consistent with the results of the experiment, with a safety factor of 0.85-1. Based on the above result, the ASME 2007 formula, a simplified version of the NASA SP 8007 formula, is regarded as a buckling formula that provides a reliable safety factor.
Stability and Accuracy Analysis for Taylor Series Numerical Method
赵丽滨; 姚振汉; 王寿梅
2004-01-01
The Taylor series numerical method (TSNM) is a time integration method for solving problems in structural dynamics. In this paper, a detailed analysis of the stability behavior and accuracy characteristics of this method is given. It is proven by a spectral decomposition method that TSNM is conditionally stable and belongs to the category of explicit time integration methods. By a similar analysis, the characteristic indicators of time integration methods, the percentage period elongation and the amplitude decay of TSNM, are derived in a closed form. The analysis plays an important role in implementing a procedure for automatic searching and finding convergence radii of TSNM. Finally, a linear single degree of freedom undamped system is analyzed to test the properties of the method.
Numerical analysis of divertor plasma for demo-CREST
Ishida, M.; Maeki, K.; Hatayama, A. [Graduate School of Fundamental Science and Technology, Keio University, Yokohama (Japan); Hiwatari, R. [Central Research Institute of Electric Power Industry (CRIEPI), Tokyo (Japan); Bonnin, X. [LIMHP-CNRS, Universite Paris 13, Villetaneuse (France); Zhu, S. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Schneider, R. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Greifswald (Germany); Coster, D. [Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, Garching (Germany)
2010-05-15
The numerical analysis of the demonstration fusion reactor Demo-CREST has been carried out; this analysis focuses on impurity seeding. Several design activities for DEMO have been carried out; however, its detailed divertor plasma analysis remains to be carried out. Therefore, in this study, we discuss the possibility of neon puffing in demo-CREST to decrease the power load to the divertor plate by using the B2-EIRENE code. It has been shown that the radiation power loss by neon increases with upstream plasma density and that the peak power load to the divertor plate comes close to the allowable level by using the preliminary divertor configuration (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Word, J Q; Ward, J A; Woodruff, D L
1990-09-01
The Battelle/Marine Sciences Laboratory (MSL) was contracted by the US Army Corps of Engineers, San Francisco District, to perform bulk sediment analysis and oyster larvae bioassays (elutriate) on sediments from Inner Oakland Harbor, California. Analysis of sediment characteristics by MSL indicated elevated priority pollutants, PAHs, pesticides, metals, organotins, and oil and grease concentrations, when compared to Alcatraz Island Dredged Material Disposal Site sediment concentrations. Larvae of the Pacific oyster, Crassostrea gigas, were exposed to seawater collected from the Alcatraz Island Site water, and a series of controls using water and sediments collected from Sequim Bay, Washington. Exposure of larvae to the Alcatraz seawater and the 50% and 100% elutriate concentrations from each Oakland sediment resulted in low survival and a high proportion of abnormal larvae compared to Sequim Bay control exposures. MSL identified that field sample collection, preservation, and storage protocols used by Port of Oakland contractors were inconsistent with standard accepted practices. 23 refs., 10 figs., 40 tabs.
Numerical analysis of frictional heat generation in bicycle disc brake
Tahmid, Shadman; Alam, Saima
2017-06-01
Precise braking operations are pivotal to ensure safety in modern day vehicle designs. Brakes are mechanical devices for increasing the frictional resistance that obstructs the turning motion of vehicle wheels by absorbing either kinetic, potential energy or both while in action. This absorbed energy appears in the form of heat. Stress, distribution of friction on surface, frictional heat generation, material and geometry are the major controlling factors for efficiency of braking operations. Frictional heat generation and its effective dissipation is one of the most predominant of these factors and hence it is the focus of this study. The purpose of this study is to analyze the thermal behavior of a full bicycle disc brake using finite element method. Sequential thermal structured method based on Ansys 14.5 is used to carry out the numerical simulation for evaluating the variation of total heat flux and temperature profiles with respect to time. The analysis model was studied experimentally and results obtained by numerical analysis were within 3% of the experimental result for maximum temperature. The model is thus adequately validated to be followed for a similar analysis on bicycle brakes.
Numerical method in biomechanical analysis of intramedullary osteosynthesis in children
A. Krauze
2006-02-01
Full Text Available Purpose: The paper presents the biomechanical analysis of intramedullary osteosynthesis in 5-7 year old children.Design/methodology/approach: The numerical analysis was performed for two different materials (stainless steel – 316L and titanium alloy – Ti-6Al-4V and for two different fractures of the femur (1/2 of the bone shaft, and 25 mm above. Furthermore, the stresses between the bone fragments were calculated while loading the femur with forces derived from the trunk mass. In the research the Metaizeau method was applied. This method ensures appropriate fixation without complications.Findings: The numerical analysis shows that stresses in both the steel and the titanium alloy nails didn’t exceed the yield point: for the stainless steel Rp0,2,min = 690 MPa and for the titanium alloy Rp0,2,min = 895 MPa.Research limitations/implications: The obtained results are the basis for the optimization of mechanical properties of the metallic biomaterial.Practical implications: On the basis of the obtained results it can be stated that both stainless steel and titanium alloy nails can be aplied in elastic osteosythesis in femur fractures in children.Originality/value: The obtain results can be used by physicians to ensure elastic osteosythesis that accelerate bone union.
Numerical MLPG Analysis of Piezoelectric Sensor in Structures
Staňák, Peter; Sládek, Ján; Sládek, Vladimír; Krahulec, Slavomír
2014-07-01
The paper deals with a numerical analysis of the electro-mechanical response of piezoelectric sensors subjected to an external non-uniform displacement field. The meshless method based on the local Petrov-Galerkin (MLPG) approach is utilized for the numerical solution of a boundary value problem for the coupled electro-mechanical fields that characterize the piezoelectric material. The sensor is modeled as a 3-D piezoelectric solid. The transient effects are not considered. Using the present MLPG approach, the assumed solid of the cylindrical shape is discretized with nodal points only, and a small spherical subdomain is introduced around each nodal point. Local integral equations constructed from the weak form of governing PDEs are defined over these local subdomains. A moving least-squares (MLS) approximation scheme is used to approximate the spatial variations of the unknown field variables, and the Heaviside unit step function is used as a test function. The electric field induced on the sensor is studied in a numerical example for two loading scenarios.
NUMERICAL ANALYSIS OF DELAMINATION GROWTH FOR STIFFENED COMPOSITE LAMINATED PLATES
白瑞祥; 陈浩然
2004-01-01
A study of postbuckling and delamination propagation behavior in delaminated stiffened composite plates was presented. A methodology was proposed for simulating the multi-failure responses, such as initial and postbuckling, delamination onset and propagation, etc. A finite element analysis was conducted on the basis of the Mindlin first order shear effect theory and the von-Krmn nonlinear deformation assumption. The total energy release rate used as the criteria of delamination growth was estimated with virtual crack closure technique (VCCT). A self-adaptive grid moving technology was adopted to model the delamination growth process. Moreover, the contact effect along delamination front was also considered during the numerical simulation process. By some numerical examples, the influence of distribution and location of stiffener, configuration and size of the delamination, boundary condition and contact effect upon the delamination growth behavior of the stiffened composite plates were investigated. The method and numerical conclusion provided should be of great value to engineers dealing with composite structures.
Numerical analysis of decoy state quantum key distribution protocols
Harrington, Jim W [Los Alamos National Laboratory; Rice, Patrick R [Los Alamos National Laboratory
2008-01-01
Decoy state protocols are a useful tool for many quantum key distribution systems implemented with weak coherent pulses, allowing significantly better secret bit rates and longer maximum distances. In this paper we present a method to numerically find optimal three-level protocols, and we examine how the secret bit rate and the optimized parameters are dependent on various system properties, such as session length, transmission loss, and visibility. Additionally, we show how to modify the decoy state analysis to handle partially distinguishable decoy states as well as uncertainty in the prepared intensities.
Analysis and numerical simulation of the dynamics of bubbles
Méndez Rodríguez, Num
2010-01-01
This project will consist of the following tasks: - analysis of the mathematical models for oscillating bubbles (axisymmetric and non-axisymmetric cases). - numerical simulation of different phenomena related with oscillating bubbles. Este trabajo tiene como objetivo el estudio y simulación de la diámica de burbujas. Inicialmente se introducen los modelos matemáticos de burbujas esféricas, para dar paso a la formulacón tridimensional basada en el método de los elementos de contorno. Para l...
Numerical Analysis for Functional Differential and Integral Equations
Hermann BRUNNER; Tao TANG; Stefan VANDEWALLE
2009-01-01
@@ From December 3-6,2007,the Department of Mathematics at Hong Kong Baptist University hosted the International Workshop on Numerical Analysis and Computational Methods for Functional Differential and Integral Equations. This workshop,organized by Hermann Brunner of Memorial University of Newfoundland (Canada) & Hong Kong Baptist University,Leevan Ling and Tao Tang of Hong Kong Baptist University,and Chengjian Zhang of Huazhong University of Science and Technology (China) brought together some 40 members of research groups in Hong Kong,Taiwan and the mainland of China,Belgium,Canada,Japan,and Portugal.
Numerical analysis of sound transmission loss using FDTD method
Murakami, Keiichi; Aoyama, Takashi; 村上, 桂一; 青山, 剛史
2009-01-01
This paper provides the results of a numerical analysis on sound transmission loss of a thin aluminum plate. The finite difference time domain (FDTD) method is used in this study because it simultaneously solves both sound wave propagation in fluid and elastic wave propagation in solid. The calculated value of sound transmission loss gives good agreement with that of mass law. Sound transmission of saw-shaped wave approximated by the sum of sine waves is also calculated. As a result, it is co...
Numerical analysis of flow fields generated by accelerating flames
Kurylo, J.
1977-12-01
Presented here is a numerical technique for the analysis of non-steady flow fields generated by accelerating flames in gaseous media. Of particular interest in the study is the evaluation of the non-steady effects on the flow field and the possible transition of the combustion process to detonation caused by an abrupt change in the burning speed of an initially steady flame propagating in an unconfined combustible gas mixture. Optically recorded observations of accelerating flames established that the flow field can be considered to consist of non-steady flow fields associated with an assembly of interacting shock waves, contact discontinuities, deflagration and detonation fronts. In the analysis, these flow fields are treated as spatially one-dimensional, the influence of transport phenomena is considered to be negligible, and unburned and burned substances are assumed to behave as perfect gases with constant, but different, specific heats. The basis of the numerical technique is an explicit, two step, second order accurate, finite difference scheme employed to integrate the flow field equations expressed in divergence form. The burning speed, governing the motion of the deflagration, is expressed in the form of a power law dependence on pressure and temperature immediately ahead of its front. The steady wave solution is obtained by the vector polar interaction technique, that is, by determining the point of intersection between the loci of end states in the plane of the two interaction invariants, pressure and particle velocity. The technique is illustrated by a numerical example in which a steady flame experiences an abrupt change in its burning speed. Solutions correspond either to the eventual reestablishment of a steady state flow field commensurate with the burning speed or to the transition to detonation. The results are in satisfactory agreement with experimental observations.
Numerical Analysis of Structural Progressive Collapse to Blast Loads
HAO Hong; WU Chengqing; LI Zhongxian; ABDULLAH A K
2006-01-01
After the progressive collapse of Ronan Point apartment in UK in 1968,intensive research effort had been spent on developing guidelines for design of new or strengthening the existing structures to prevent progressive collapse.However,only very few building design codes provide some rather general guidance,no detailed design requirement is given.Progressive collapse of the Alfred P.Murrah Federal building in Oklahoma City and the World Trade Centre (WTC) sparked again tremendous research interest on progressive collapse of structures.Recently,US Department of Defence (DoD) and US General Service Administration (GSA) issued guidelines for structure progressive collapse analysis.These two guidelines are most commonly used,but their accuracy is not known.This paper presents numerical analysis of progressive collapse of an example frame structure to blast loads.The DoD and GSA procedures are also used to analyse the same example structure.Numerical results are compared and discussed.The accuracy and the applicability of the two design guidelines are evaluated.
Analysis and Numerical Treatment of Elliptic Equations with Stochastic Data
Cheng, Shi
Many science and engineering applications are impacted by a significant amount of uncertainty in the model. Examples include groundwater flow, microscopic biological system, material science and chemical engineering systems. Common mathematical problems in these applications are elliptic equations with stochastic data. In this dissertation, we examine two types of stochastic elliptic partial differential equations(SPDEs), namely nonlinear stochastic diffusion reaction equations and general linearized elastostatic problems in random media. We begin with the construction of an analysis framework for this class of SPDEs, extending prior work of Babuska in 2010. We then use the framework both for establishing well-posedness of the continuous problems and for posing Galerkintype numerical methods. In order to solve these two types of problems, single integral weak formulations and stochastic collocation methods are applied. Moreover, a priori error estimates for stochastic collocation methods are derived, which imply that the rate of convergence is exponential, along with the order of polynomial increasing in the space of random variables. As expected, numerical experiments show the exponential rate of convergence, verified by a posterior error analysis. Finally, an adaptive strategy driven by a posterior error indicators is designed.
NUMERICAL ANALYSIS OF THE MECHANICS OF SOIL REINFORCEMENT
Weifeng SONG; Lihua CHEN; Xiuping LIU
2006-01-01
Roots affect the soil stress and strain and contribute to soil reinforcement. An analysis of stress and strain in the root-soil composite is presented which combines roots, soils, and an interface element by using the Duncan-Chang E-μmodel and a nonlinear-interface-element model. In this research, a finite element numerical analysis method was applied to simulate the stress field resulting in a composite of Pinus tabulaeformis roots and soils. Results show that roots can transmit the stress from surface soils to deep soils, and can reduce soil stress within the surface soil layer; results also show that the effect of soil reinforcement by roots is limited to surface soils. The Slope Safety Index of a pine slope becomes 10% higher than that of a natural slope, indicating that roots have a significant effect on soil reinforcement.
Modal interval analysis new tools for numerical information
Sainz, Miguel A; Calm, Remei; Herrero, Pau; Jorba, Lambert; Vehi, Josep
2014-01-01
This book presents an innovative new approach to interval analysis. Modal Interval Analysis (MIA) is an attempt to go beyond the limitations of classic intervals in terms of their structural, algebraic and logical features. The starting point of MIA is quite simple: It consists in defining a modal interval that attaches a quantifier to a classical interval and in introducing the basic relation of inclusion between modal intervals by means of the inclusion of the sets of predicates they accept. This modal approach introduces interval extensions of the real continuous functions, identifies equivalences between logical formulas and interval inclusions, and provides the semantic theorems that justify these equivalences, along with guidelines for arriving at these inclusions. Applications of these equivalences in different areas illustrate the obtained results. The book also presents a new interval object: marks, which aspire to be a new form of numerical treatment of errors in measurements and computations.
Numerical Analysis of Combined Valve Hydrodynamic Characteristics for Turbine System
Bhowmik, P. K.; Shamim, J. A.; Gairola, A.; Arif, M.; Suh, Kune Y. [Seoul National Univ., Seoul (Korea, Republic of)
2014-05-15
precisely by the valve manufacturer. As a matter of fact, attempts were made to obtain flow characteristic curves resorting to analytical as well as numerical methods. The flow characteristic curve relates the stem lift with mass flow rate at a specific temperature and pressure. This paper focuses on computational and numerical analysis of the combined stop and control valve. Combined Airflow Regulation Analysis (CARA) is performed to check on the hydrodynamic characteristic, which is represented by flow coefficient characteristic. CATIA V.5 and ANSYS CFX are used for three-dimensional computer-aided design and computational fluid dynamics (CFD) analysis, respectively. Flow characteristic curves are plotted by calculating theoretical and numerical mass flow rate. Hydrodynamic analysis was made of the combined stop and control valve for the turbine system using ANSYS CFX. The result of the numerical study represented by the valve flow coefficient with different normalized values of valve stem movement L/D and different pressure ratios of valve outlet and inlet agrees well with the ideal case and other similar previous experimental results. This study also provided a solid understanding with versatile options for analyzing the hydrodynamics of the combined valve considering the various internal geometry, seat, plug, and the inlet plus outlet boundary conditions to improve the efficiency, performance and reliability of the turbine system of small as well as large power conversion system using the numerical analysis with minimal cost and time.
Submarine harbor navigation using image data
Stubberud, Stephen C.; Kramer, Kathleen A.
2017-01-01
The process of ingress and egress of a United States Navy submarine is a human-intensive process that takes numerous individuals to monitor locations and for hazards. Sailors pass vocal information to bridge where it is processed manually. There is interest in using video imaging of the periscope view to more automatically provide navigation within harbors and other points of ingress and egress. In this paper, video-based navigation is examined as a target-tracking problem. While some image-processing methods claim to provide range information, the moving platform problem and weather concerns, such as fog, reduce the effectiveness of these range estimates. The video-navigation problem then becomes an angle-only tracking problem. Angle-only tracking is known to be fraught with difficulties, due to the fact that the unobservable space is not the null space. When using a Kalman filter estimator to perform the tracking, significant errors arise which could endanger the submarine. This work analyzes the performance of the Kalman filter when angle-only measurements are used to provide the target tracks. This paper addresses estimation unobservability and the minimal set of requirements that are needed to address it in this complex but real-world problem. Three major issues are addressed: the knowledge of navigation beacons/landmarks' locations, the minimal number of these beacons needed to maintain the course, and update rates of the angles of the landmarks as the periscope rotates and landmarks become obscured due to blockage and weather. The goal is to address the problem of navigation to and from the docks, while maintaining the traversing of the harbor channel based on maritime rules relying solely on the image-based data. The minimal number of beacons will be considered. For this effort, the image correlation from frame to frame is assumed to be achieved perfectly. Variation in the update rates and the dropping of data due to rotation and obscuration is considered
Narrow harbors. Few joint ventures will find haven in the investment-interest safe harbor.
Lepper, G J; Swoboda, J
1991-12-01
Investors and potential investors had hoped for meaningful guidance from the safe harbor regulations on appropriate structures for healthcare joint ventures. Unfortunately, the narrowly drawn final investment-interest safe harbor offers relatively little meaningful guidance or protection for the vast majority of such ventures. The Illegal Remuneration Statute (also known as the fraud and abuse statute) was first enacted in 1972 to prohibit members of the healthcare community from exchanging patient referrals for any kind of remuneration. In 1987 Congress instructed the secretary of Health and Human Services to create "safe harbors" for legitimate payment practices that, although they may violate the statute's strict prohibition, will be protected from prosecution. The investment-interest safe harbor has garnered the most attention. It provides two safe harbors, one for investments in large entities and one for investments in small entities. Both safe harbors contain onerous threshold requirements and other restrictions that diminish the usefulness of the safe harbor for all but a very few ventures. In addition, the Office of the Inspector General has created other obstacles to forming and preserving "safe" healthcare business ventures, including a refusal to "grandfather" or create a "safe harbor restructuring period" for existing business arrangements. Because most existing or planned joint ventures do not qualify for the investment-interest safe harbor, investors are forced to make their business decisions on the basis of the same factors used before publication of the safe harbor regulations. Such analysis will continue to focus on factors that demonstrate organizations' intent in making payments to investors as a return on investments.
Numerical Analysis of Asphalt Pavements under Moving Wheel Loads
无
2006-01-01
The responses of the pavement in service are the basis for the design of the semi-rigid base course asphalt pavement.Due to the dynamic characteristics of wheel loads and the temperature loads,the dynamic response analysis is very significant.In this article, the dynamic analysis of asphalt pavement under moving wheel loads is carried out using finite element method coupled with non-reflective boundary method.The influences of the base modulus, thickness, the vehicle velocity, the tire pressure, and the contact condition at the interface are studied using parametric analysis.The results of numerical analysis show that it is not appropriate to simply increase the base modulus or thickness in the design.It would be beneficial if the base design is optimized synthetically.The increase of damping is also beneficial to the pavements because of the surface deflection and the stresses declination.Furthermore, the good contact condition at the interface results in good performance because it combines every layer of the pavement to work together.As overload aggravates the working condition of the pavement, it is not allowed.
Numerical Analysis of Erosion Caused by Biomimetic Axial Fan Blade
Jun-Qiu Zhang
2013-01-01
Full Text Available Damage caused by erosion has been reported in several industries for a wide range of situations. In the present work, a new method is presented to improve the erosion resistance of machine components by biomimetic method. A numerical investigation of solid particle erosion in the standard and biomimetic configuration blade of axial fan is presented. The analysis consists in the application of the discrete phase model, for modeling the solid particles flow, and the Eulerian conservation equations to the continuous phase. The numerical study employs computational fluid dynamics (CFD software, based on a finite volume method. User-defined function was used to define wear equation. Gas/solid flow axial fan was simulated to calculate the erosion rate of the particles on the fan blades and comparatively analyzed the erosive wear of the smooth surface, the groove-shaped, and convex hull-shaped biomimetic surface axial flow fan blade. The results show that the groove-shaped biomimetic blade antierosion ability is better than that of the other two fan blades. Thoroughly analyze of antierosion mechanism of the biomimetic blade from many factors including the flow velocity contours and flow path lines, impact velocity, impact angle, particle trajectories, and the number of collisions.
Numerical and Experimental Stress Analysis of a Composite Leaf Spring
Kaveri A. Katake
2016-10-01
Full Text Available Automobile sector is always focusing on enhancing level of comfort, fuel economy, customer satisfaction and safety. Vehicle weight reduction increases the overall fuel efficiency. Use of composite materials has made it possible to reduce the weight of the vehicle, without reduction in load carrying capacity. Now a day's manufacturers and researchers are trying to replace conventional material parts with composites. The composite materials have more elastic strain energy storage capacity and high strength to weight ratio as compared to steel. This paper is related to Numerical and experimental strength analysis of suspension leaf springs for a light motor vehicle made of composite materials. Two materials Glass Fiber Reinforced Plastic (GFRP and Carbon Fiber Reinforced Plastic (CFRP are selected for manufacturing of leaf spring. The strength of these composite depends on angle orientation, volume to weight ratio of reinforcement and length to depth ratio of fiber. In this work two leaf springs made of GFRP and a sandwich of CFRP and GFRP are developed. Numerical and experimental static stress analyses are carried out for these two springs. These results are compared with analytical results of conventional metal spring. The comparison shows that composite material springs have compatible strength to withstand load. Comparative results for weight, cost and deformation are presented at the end of the paper.
POLLUTANT EMISSION NUMERICAL ANALYSIS OF A MARINE ENGINE
DOREL DUMITRU VELCEA
2016-06-01
Full Text Available The energies produced by the diesel engines of strong power are largely used in marine propulsion because of their favorable reliability and their significant output. However, the increasingly constraining legislations, aimed at limiting the pollutant emissions from the exhaust gas produced by these engines, tend to call into question their supremacy. The analysis of the pollutant emissions and their reduction in the exhaust gas of the slow turbocharged marine diesel engine using ANSYS 15 constitutes the principal objective of this study. To address problems of global air pollution due to the pollutant emission from fuel oil engin e combustion, it is necessary to understand the mechanisms by which pollutants are produced in combustion processes. In the present work, an experimental and numerical study is carried out on a unit of real use aboard a car ferry ship. A numerical model based on a detailed chemical kinetics scheme is used to calculate the emissions of NOx, SOx and Sooth in an internal combustion engine model for the same characteristics of the real unit.
Saito, T; Guthmuller, H; DeWeert, M
2004-12-15
Port and Harbor Security is a daunting task to which optics and photonics offers significant solutions. We are pleased to report that the 2005 Defense and Security Symposium (DSS, Orlando, FL) will include reports on active and passive photonic systems operating from both airborne and subsurface platforms. In addition to imaging techniques, there are various photonic applications, such as total internal reflection fluorescence (TIRF), which can be used to ''sniff'' for traces of explosives or contaminants in marine. These non-imaging technologies are beyond the scope of this article, but will also be represented at DSS 2005. We encourage colleagues to join our technical group to help us to make our ports and harbors safer and more secure.
Numerical analysis of the dynamics of distributed vortex configurations
Govorukhin, V. N.
2016-08-01
A numerical algorithm is proposed for analyzing the dynamics of distributed plane vortex configurations in an inviscid incompressible fluid. At every time step, the algorithm involves the computation of unsteady vortex flows, an analysis of the configuration structure with the help of heuristic criteria, the visualization of the distribution of marked particles and vorticity, the construction of streamlines of fluid particles, and the computation of the field of local Lyapunov exponents. The inviscid incompressible fluid dynamic equations are solved by applying a meshless vortex method. The algorithm is used to investigate the interaction of two and three identical distributed vortices with various initial positions in the flow region with and without the Coriolis force.
Experimental and numerical analysis of cavitating flow around a hydrofoil
Müller Miloš
2012-04-01
Full Text Available The paper describes experiments carried out in the cavitation tunnel with the rectangular test section of 150 × 150 × 500 mm and the maximum test section inlet velocity of 25 m/s. These experiments have been aimed to visualize the cavitation phenomena as well as to quantify the erosion potential using pitting tests evaluated during the incubation period for the cast-iron prismatic hydrofoil with the modified NACA profile. A bypass section installed in the tunnel has allowed to measure the nuclei content in the inlet flow to the test section using the acoustic spectrometer. The measured data have been compared with the CFD analysis of the cavitation phenomena on the hydrofoil as well as the numerically determined location and magnitude of the first calculated collapses of the cavitating bubbles with a good agreement.
NUMERICAL METHOD AND RANDOM ANALYSIS OF CEMENT CONCRETE EXPANSION
无
2000-01-01
The numerical method and random analysis of cement concrete expansion are given. A mathematical procedure is presented which includes the nonlinear characteristics of the concrete. An expression is presented to predict the linear restrained expansion of expansive concrete bar restrained by a steel rod. The results indicate a rapid change in strains and stresses within initial days, after which the change gradually decreases. A reliable and accurate method of predicting the behavior of the concrete bulkheads in drifts is presented here. Extensive sensitivity and parametric studies have been performed. The random density distributions of expansive concrete are given based on the restricted or unrestricted condition. These studies show that the bulkhead stress fields are largely influenced by the early modulus of the concrete and the randomness of the ultimate unrestrained expansion of the concrete.
Numerical Analysis for Structural Safety Evaluation of Butterfly Valves
Shin, Myung-Seob; Yoon, Joon-Yong; Park, Han-Yung
2010-06-01
Butterfly valves are widely used in current industry to control the fluid flow. They are used for both on-off and throttling applications involving large flows at relatively low operating pressure especially in large size pipelines. For the industrial application of butterfly valves, it must be ensured that the valve could be used safety under the fatigue life and the deformations produced by the pressure of the fluid. In this study, we carried out the structure analysis of the body and the valve disc of the butterfly valve and the numerical simulation was performed by using ANSYS v11.0. The reliability of valve is evaluated under the investigation of the deformation, the leak test and the durability of the valve.
Numerical Analysis of Vibrations of Structures under Moving Inertial Load
Bajer, Czeslaw I
2012-01-01
Moving inertial loads are applied to structures in civil engineering, robotics, and mechanical engineering. Some fundamental books exist, as well as thousands of research papers. Well known is the book by L. Frýba, Vibrations of Solids and Structures Under Moving Loads, which describes almost all problems concerning non-inertial loads. This book presents broad description of numerical tools successfully applied to structural dynamic analysis. Physically we deal with non-conservative systems. The discrete approach formulated with the use of the classical finite element method results in elemental matrices, which can be directly added to global structure matrices. A more general approach is carried out with the space-time finite element method. In such a case, a trajectory of the moving concentrated parameter in space and time can be simply defined. We consider structures described by pure hyperbolic differential equations such as strings and structures described by hyperbolic-parabolic differential equations ...
EXPERIMENTAL INVESTIGATION & NUMERICAL ANALYSIS OF COMPOSITE LEAF SPRING
K. K. JADHAO,
2011-06-01
Full Text Available The Automobile Industry has shown keen interest for replacement of steel leaf spring with that of glass fiber composite leaf spring, since the composite material has high strength to weight ratio, good corrosion resistance and tailor-able properties. The objective of present study was to replace material for leaf spring. In present study the material selected was glass fiber reinforced plastic (GFRP and the polyester resin (NETPOL 1011 can be used which was more economical this will reduce total cost of composite leaf spring. A spring with constant width and thickness was fabricated by hand lay-up technique which was very simple and economical. The experiments were conducted on UTM and numerical analysis was done via (FEA using ANSYS software. Stresses and deflection results were verified for analytical and experimental results. Result shows that, the composite spring has stresses much lower than steel leaf spring and weight of composite spring was nearly reduced up to 85%.
Deterministic and stochastic error bounds in numerical analysis
Novak, Erich
1988-01-01
In these notes different deterministic and stochastic error bounds of numerical analysis are investigated. For many computational problems we have only partial information (such as n function values) and consequently they can only be solved with uncertainty in the answer. Optimal methods and optimal error bounds are sought if only the type of information is indicated. First, worst case error bounds and their relation to the theory of n-widths are considered; special problems such approximation, optimization, and integration for different function classes are studied and adaptive and nonadaptive methods are compared. Deterministic (worst case) error bounds are often unrealistic and should be complemented by different average error bounds. The error of Monte Carlo methods and the average error of deterministic methods are discussed as are the conceptual difficulties of different average errors. An appendix deals with the existence and uniqueness of optimal methods. This book is an introduction to the area and a...
Numerical Analysis of Quality Inspection of Anchorage System
ZHANGYongxing; XUMing
2002-01-01
Sonoprobe method has been applied in non-destructive inspection of anchorage project.The fundament is that dynamic transient excitation causes the elastic vibration of an anchor bar,and flaws can be estimated or deduced by determining transient response of the anchor bar.FEA numeric solution of hyperbolic equation indicates that deductions must comply with acoustic parameters such as velocity of sound,vibration range,wave shape etc when inspecting interior flaws in the grout of an anchor bar,Based on wavelet packet analysis,the energy eigenvector is a flaw vector,which could be regarded as the basis in the nondestructive inspection of anchors,As a non-linear dynamical system,artifical neural networks dealing with quality insection of gray system have been proved efficient.
Numerical Simulation on Flood Routing in the Inland Excavated-in Harbor Basin%内河挖入式港池洪水演进数值模拟
王剑楠; 李彬; 郑国栋; 庄佳
2015-01-01
For straight inland excavated-in harbor basin,unsteady flow was generalized to simulate flood routing in different scale excavated-in harbor basin river channels and explored the impact of harbor depth dimension to flood flowing in river. The simulation results show that:a)there is very small action of water drainage and drag reduction(flattening effect)for inflow and outflow in the harbor reach;there is no significant effect of detention storage. b)uplifting the water level of local harbor reaches,lowering the water level of other reaches,the effect of raising or lowering is small,elevated water level is not designed to enhance the river flood control standards. c)the diversion ratio of har-bor area is much smaller than the ratio of the basin depth and rectangular river width,the harbor area has little effect on flood routing and is not the main channel of flood routing. In summary,the excavated-in harbor basin has not adverse effects on flood flowing in river;excavated-in harbor basins can be built to increase shoreline resources available of Pearl River area network port;the new pier or wharf may increase the size of the original lifting capacity.%针对内河顺直河段“挖入式港池”，采用概化非恒定流，模拟了不同规模“挖入式港池”河道的洪水演进过程，探究了港池进深对河道行洪的影响。模拟结果表明：①“港区”对其所在河段进（出）口水流有很小的引流减阻作用（坦化作用），无明显滞洪调蓄作用；②“港区”抬升其出口断面附近的水位，降低其他河段的水位，抬升（降低）作用很小，升高的水位不提升河道设计防洪标准；③“港区”分流比远小于港池进深与矩形河宽的比值，“港区”参与河道行洪作用很小，不是河道泄洪的主要通道。“挖入式港池”对河道行洪不会产生明显不利影响，可通过修建“挖入式港池”增加珠三角网河区港口可用岸线资源量
Numerical Analysis of Flow through Shrouded Turbine Cascade
S. Thanigaiarasu
2013-10-01
Full Text Available The aim of the work is to estimate the secondary flow losses through the gap between the shrouded turbine rotor blades. Aerodynamic losses occurring in flow such as profile, secondary flow and leakage were analyzed. The numerical results of flow over a single shrouded turbine rotor blade, cascade analysis of two shrouded turbine rotor blade with zero gap and leakage analysis through the 2mm z-gap of the shrouded turbine rotor blade are presented. First, a single shrouded turbine rotor blade was analyzed and the pressure coefficient on the surface of the blade at midsection of blade is taken as reference. For this, the geometry of a shrouded HP turbine rotor is chosen. GAMBIT software is used for designing and analyzed using FLUENT software. Secondly cascade analysis was also carried out using the same procedure and the pressure coefficient is compared with the reference pressure coefficient profile and found that changes in the pressure coefficient on the blade surface. Finally the two shrouded turbine rotor blades with 2mm z-gap between the shrouds are created and analyzed using the same procedure and the pressure coefficient was compared with the reference pressure coefficient profile and found that decrease in the pressure coefficient on the blade surface near the shroud is because of the leakage of flow through the z-gap between the shrouds. The leakage lessens the end wall boundary layer separation near shroud of the turbine rotor blade with 2mm z-gap.
Economic Impact of Cruise Ship Passengers in Bar Harbor, Maine
Gabe, Todd; Lynch, Colleen; McConnon, James; Allen, Thomas
2003-01-01
This report examines the economic impact of cruise ship passengers in Bar Harbor, Maine. In 2002, 64 cruise ships docked in Bar Harbor carrying about 120,000 passengers and crewmembers. The analysis presented in the report is based on 1,080 passenger surveys conducted between August and October of 2002. Economic impact figures are based on a total of 97,190 passengers, which is the capacity of the 64 cruise ships that were scheduled to visit Bar Harbor in 2002.
Numerical analysis of field-scale transport of bromacil
Russo, David; Tauber-Yasur, Inbar; Laufer, Asher; Yaron, Bruno
Field-scale transport of bromacil (5-bromo-3- sec-butyl-6-methyluracil) was analyzed using two different model processes for local description of the transport. The first was the classical, one-region convection dispersion equation (CDE) model while the second was the two-region, mobile-immobile (MIM) model. The analyses were performed by means of detailed three-dimensional, numerical simulations of the flow and the transport [Russo, D., Zaidel, J. and Laufer, A., Numerical analysis of flow and transport in a three-dimensional partially saturated heterogeneous soil. Water Resour. Res., 1998, in press], employing local soil hydraulic properties parameters from field measurements and local adsorption/desorption coefficients and the first-order degradation rate coefficient from laboratory measurements. Results of the analyses suggest that for a given flow regime, mass exchange between the mobile and the immobile regions retards the bromacil degradation, considerably affects the distribution of the bromacil resident concentration, c, at relatively large travel times, slightly affects the spatial moments of the distribution of c, and increases the skewing of the bromacil breakthrough and the uncertainty in its prediction, compared with the case in which the soil contained only a single (mobile) region. Mean and standard deviation of the simulated concentration profiles at various elapsed times were compared with measurements from a field-scale transport experiment [Tauber-Yasur, I., Hadas, A., Russo, D. and Yaron, B., Leaching of terbuthylazine and bromacil through field soils. Water, Air Soil Poln., 1998, in press] conducted at the Bet Dagan site. Given the limitations of the present study (e.g. the lack of detailed field data on the spatial variability of the soil chemical properties) the main conclusion of the present study is that the field-scale transport of bromacil at the Bet Dagan site is better quantified with the MIM model than the CDE model.
Numerical Analysis of Piles in Layered Soils: A Parametric Study
Ravi Kumar Reddy C
2015-04-01
Full Text Available In this paper, numerical analysis of a pile-soil interaction problem is presented considering the parameters influencing the axial load-deformation behavior of the pile embedded in a layered soil medium. The analysis is demonstrated with parametric solutions of a pile with underlain model soil strata under the axial force. An attempt is made to ascertain the extent of influence of elastic properties of the pile, geometry of the pile, end conditions of the pile and the elastic properties of the underlain soil strata on the response of the piles under axial loads lying in a model soil layers in terms of the settlement of the pile and the internal deformation of the pile. The study revealed that the increase in modulus of elasticity of pile improves the settlement resistance of the pile, increase in the ratio of cross sectional dimensions causes decrease in the top deformations of the pile, the settlement of the pile reduced to a great extent when the cross section of the pile adopted is non circular instead of circular and increase in the elastic modulii of top and bottom layers of soil has decreased the settlement of the pile to a great extent, but elastic modulus of soil layers other than top and bottom has got negligible influence on the settlement of the pile.
Calcutt, Michael J; Foecking, Mark F; Hsieh, Hsin-Yeh; Adkins, Pamela R F; Stewart, George C; Middleton, John R
2015-02-19
Staphylococcus hyicus is the primary etiological agent of exudative epidermitis in swine. Analysis of the complete genome sequence of the type strain revealed a locus encoding a type VII secretion system and a large chromosomal island harboring the genes encoding exfoliative toxin ExhA and an EDIN toxin homolog.
SAMSAN- MODERN NUMERICAL METHODS FOR CLASSICAL SAMPLED SYSTEM ANALYSIS
Frisch, H. P.
1994-01-01
SAMSAN was developed to aid the control system analyst by providing a self consistent set of computer algorithms that support large order control system design and evaluation studies, with an emphasis placed on sampled system analysis. Control system analysts have access to a vast array of published algorithms to solve an equally large spectrum of controls related computational problems. The analyst usually spends considerable time and effort bringing these published algorithms to an integrated operational status and often finds them less general than desired. SAMSAN reduces the burden on the analyst by providing a set of algorithms that have been well tested and documented, and that can be readily integrated for solving control system problems. Algorithm selection for SAMSAN has been biased toward numerical accuracy for large order systems with computational speed and portability being considered important but not paramount. In addition to containing relevant subroutines from EISPAK for eigen-analysis and from LINPAK for the solution of linear systems and related problems, SAMSAN contains the following not so generally available capabilities: 1) Reduction of a real non-symmetric matrix to block diagonal form via a real similarity transformation matrix which is well conditioned with respect to inversion, 2) Solution of the generalized eigenvalue problem with balancing and grading, 3) Computation of all zeros of the determinant of a matrix of polynomials, 4) Matrix exponentiation and the evaluation of integrals involving the matrix exponential, with option to first block diagonalize, 5) Root locus and frequency response for single variable transfer functions in the S, Z, and W domains, 6) Several methods of computing zeros for linear systems, and 7) The ability to generate documentation "on demand". All matrix operations in the SAMSAN algorithms assume non-symmetric matrices with real double precision elements. There is no fixed size limit on any matrix in any
Operational modal analysis of harbor crane under ambient excitation%基于环境激励的港口起重机工作模态分析
龚凌诸; 杨晓翔; 钟舜聪; 郭金泉; 许忠福; 梁崇忠
2011-01-01
Aiming at solving the excitation problems of a 40 t harbor crane, operational modal analysis using natural excitation technique (NEXT) were investigated. Ambient excitation, such as that caused by wind, was employed to excite the crane. With the unknown input (excitation) signal, only the response signals were recorded. Taking one of the response signals as the reference, the cross power spectra of response signals were calculated and used for modal identification of the crane. The first four lower modal parameters ( frequencies, damping ratios and mode shapes) were obtained. The results indicate that operational modal analysis of harbor cranes using NExT is applicable.Therefore, NExT could bo recommended in modal testing and analysis of other special equipments.%针对港口起重机难以施加激振力的问题,采用自然环境激励技术(NExT)对港口起重机进行了工作模态分析.在自然风的随机激励下,对某港口40t位起重机进行了模态试验.采用响应点与参考点之间的互功率谱的幅值图代替集总传递函数的幅值图进行了模态分析.由所有测点和参考点间的互功率谱,通过拟合各响应点同参考点之间的互功率谱来识别起重机前4阶低阶模态参数(振型、频率和阻尼).研究结果表明,利用环境激励法对港口起重机的模态参数识别是行之有效的,该方法可推广应用于其他大型特种设备的模态试验和分析.
A Computer-Based Content Analysis of Interview Texts: Numeric Description and Multivariate Analysis.
Bierschenk, B.
1977-01-01
A method is described by which cognitive structures in verbal data can be identified and categorized through numerical analysis and quantitative description. Transcriptions of interviews (in this case, the verbal statements of 40 researchers) are manually coded and subjected to analysis following the AaO (Agent action Object) paradigm. The texts…
Summary of research in applied mathematics, numerical analysis, and computer sciences
1986-01-01
The major categories of current ICASE research programs addressed include: numerical methods, with particular emphasis on the development and analysis of basic numerical algorithms; control and parameter identification problems, with emphasis on effective numerical methods; computational problems in engineering and physical sciences, particularly fluid dynamics, acoustics, and structural analysis; and computer systems and software, especially vector and parallel computers.
NUMERICAL SIMULATION FOR A PROCESS ANALYSIS OF A COKE OVEN
Zhancheng Guo; Huiqing Tang
2005-01-01
A computational fluid dynamic model is established for a coking process analysis of a coke oven using PHOENICS CFD package. The model simultaneously calculates the transient composition, temperatures of the gas and the solid phases, velocity of the gas phase and porosity and density of the semi-coke phase. Numerical simulation is illustrated in predicting the evolution of volatile gases, gas flow paths, profiles of density, porosity of the coke oven charge,profiles of temperatures of the coke oven gas and the semi-coke bed. On the basis of above modeling, the flow of coke oven gas (COG) blown from the bottom of the coke oven into the porous semi-coke bed is simulated to reveal whether or not and when the blown COG can uniformly flow through the porous semi-coke bed for the purpose of desulfurizing the semi-coke by recycling the COG. The simulation results show that the blown COG can uniformly flow through the semi-coke bed only after the temperature at the center of the semi-coke bed has risen to above 900 ℃.
Numerical analysis of pile lateral behavior of pile supported embankment
荆志东; 刘力; 郑刚; 姜岩
2008-01-01
A finite difference numerical method was adopted to evaluate the pile lateral behavior of pile supported embankment. A published case history was used to verify the proposed methodology. By simulating the case history, the determination of parameters needed were verified. Then three embankments constructed on different ground conditions with different soil-pile relative stiffnesses were analyzed to study pile lateral behaviors including pile deflection and bending moment. The results show that pile deflections and bending moments induced by soil lateral deformation and embankment vertical load are different for piles at different positions under the same embankment. The relative stiffness between pile and soil affected by the properties of different reinforcing piles such as concrete pile and deep mixing method pile exert important effects on the pile lateral behavior and the pile’s failure modes. Consequently, it is necessary to consider the different piles lateral behaviors and possible failure modes at different positions and the different piles proprieties with different reinforcing methods in the embankment stability analysis.
Numeric calculation of celestial bodies with spreadsheet analysis
Koch, Alexander
2016-04-01
The motion of the planets and moons in our solar system can easily be calculated for any time by the Kepler laws of planetary motion. The Kepler laws are a special case of the gravitational law of Newton, especially if you consider more than two celestial bodies. Therefore it is more basic to calculate the motion by using the gravitational law. But the problem is, that by gravitational law it is not possible to calculate the state of motion with only one step of calculation. The motion has to be numerical calculated for many time intervalls. For this reason, spreadsheet analysis is helpful for students. Skills in programmes like Excel, Calc or Gnumeric are important in professional life and can easily be learnt by students. These programmes can help to calculate the complex motions with many intervalls. The more intervalls are used, the more exact are the calculated orbits. The sutdents will first get a quick course in Excel. After that they calculate with instructions the 2-D-coordinates of the orbits of Moon and Mars. Step by step the students are coding the formulae for calculating physical parameters like coordinates, force, acceleration and velocity. The project is limited to 4 weeks or 8 lessons. So the calcualtion will only include the calculation of one body around the central mass like Earth or Sun. The three-body problem can only be shortly discussed at the end of the project.
Direct Numerical Simulation of Combustion Using Principal Component Analysis
Owoyele, Opeoluwa; Echekki, Tarek
2016-11-01
We investigate the potential of accelerating chemistry integration during the direct numerical simulation (DNS) of complex fuels based on the transport equations of representative scalars that span the desired composition space using principal component analysis (PCA). The transported principal components (PCs) offer significant potential to reduce the computational cost of DNS through a reduction in the number of transported scalars, as well as the spatial and temporal resolution requirements. The strategy is demonstrated using DNS of a premixed methane-air flame in a 2D vortical flow and is extended to the 3D geometry to further demonstrate the computational efficiency of PC transport. The PCs are derived from a priori PCA of a subset of the full thermo-chemical scalars' vector. The PCs' chemical source terms and transport properties are constructed and tabulated in terms of the PCs using artificial neural networks (ANN). Comparison of DNS based on a full thermo-chemical state and DNS based on PC transport based on 6 PCs shows excellent agreement even for species that are not included in the PCA reduction. The transported PCs reproduce some of the salient features of strongly curved and strongly strained flames. The 2D DNS results also show a significant reduction of two orders of magnitude in the computational cost of the simulations, which enables an extension of the PCA approach to 3D DNS under similar computational requirements. This work was supported by the National Science Foundation Grant DMS-1217200.
Analysis of Numerical Simulation Results of LIPS-200 Lifetime Experiments
Chen, Juanjuan; Zhang, Tianping; Geng, Hai; Jia, Yanhui; Meng, Wei; Wu, Xianming; Sun, Anbang
2016-06-01
Accelerator grid structural and electron backstreaming failures are the most important factors affecting the ion thruster's lifetime. During the thruster's operation, Charge Exchange Xenon (CEX) ions are generated from collisions between plasma and neutral atoms. Those CEX ions grid's barrel and wall frequently, which cause the failures of the grid system. In order to validate whether the 20 cm Lanzhou Ion Propulsion System (LIPS-200) satisfies China's communication satellite platform's application requirement for North-South Station Keeping (NSSK), this study analyzed the measured depth of the pit/groove on the accelerator grid's wall and aperture diameter's variation and estimated the operating lifetime of the ion thruster. Different from the previous method, in this paper, the experimental results after the 5500 h of accumulated operation of the LIPS-200 ion thruster are presented firstly. Then, based on these results, theoretical analysis and numerical calculations were firstly performed to predict the on-orbit lifetime of LIPS-200. The results obtained were more accurate to calculate the reliability and analyze the failure modes of the ion thruster. The results indicated that the predicted lifetime of LIPS-200's was about 13218.1 h which could satisfy the required lifetime requirement of 11000 h very well.
1-D Numerical Analysis of RBCC Engine Performance
Han, Samuel S.
1998-01-01
An RBCC engine combines air breathing and rocket engines into a single engine to increase the specific impulse over an entire flight trajectory. Considerable research pertaining to RBCC propulsion was performed during the 1960's and these engines were revisited recently as a candidate propulsion system for either a single-stage-to-orbit (SSTO) or two-stage-to-orbit (TSTO) launch vehicle. There are a variety of RBCC configurations that had been evaluated and new designs are currently under development. However, the basic configuration of all RBCC systems is built around the ejector scramjet engine originally developed for the hypersonic airplane. In this configuration, a rocket engine plays as an ejector in the air-augmented initial acceleration mode, as a fuel injector in scramjet mode and the rocket in all rocket mode for orbital insertion. Computational fluid dynamics (CFD) is a useful tool for the analysis of complex transport processes in various components in RBCC propulsion systems. The objective of the present research was to develop a transient 1-D numerical model that could be used to predict flow behavior throughout a generic RBCC engine following a flight path.
Numerical Simulation and Scaling Analysis of Cell Printing
Qiao, Rui; He, Ping
2011-11-01
Cell printing, i.e., printing three dimensional (3D) structures of cells held in a tissue matrix, is gaining significant attention in the biomedical community. The key idea is to use inkjet printer or similar devices to print cells into 3D patterns with a resolution comparable to the size of mammalian cells. Achieving such a resolution in vitro can lead to breakthroughs in areas such as organ transplantation. Although the feasibility of cell printing has been demonstrated recently, the printing resolution and cell viability remain to be improved. Here we investigate a unit operation in cell printing, namely, the impact of a cell-laden droplet into a pool of highly viscous liquids. The droplet and cell dynamics are quantified using both direct numerical simulation and scaling analysis. These studies indicate that although cell experienced significant stress during droplet impact, the duration of such stress is very short, which helps explain why many cells can survive the cell printing process. These studies also revealed that cell membrane can be temporarily ruptured during cell printing, which is supported by indirect experimental evidence.
Numerical analysis of laminar forced convection in a spherical annulus
Tuft, D.B.
1980-07-21
Calculations of steady laminar incompressible fluid-flow and heat transfer in a spherical annulus are presented. Steady pressures, temperatures, velocities, and heat transfer coefficients are calculated for an insulated outer sphere and a 0/sup 0/C isothermal inner sphere with 50/sup 0/C heated water flowing in the annulus. The inner sphere radius is 13.97 cm, the outer sphere radius is 16.83 cm and the radius ratio is 1.2. The transient axisymmetric equations of heat, mass, and momentum conservation are solved numerically in spherical coordinates. The transient solution is carried out in time until steady state is achieved. A variable mesh is used to improve resolution near the inner sphere where temperature and velocity gradients are steep. It is believed that this is the first fully two-dimensional analysis of forced flow in a spherical annulus. Local and bulk Nusselt numbers are presented for Reynolds numbers from 4.4 to 440. Computed bulk Nusselt numbers ranged from 2 to 50 and are compared to experimental results from the literature. Inlet flow jetting off the inner sphere and flow separation are predicted by the analysis. The location of wall jet separation was found to be a function of Reynolds number, indicating the location of separation depends upon the ratio of inertia to viscous forces. Wall jet separation has a pronounced effect on the distribution of local heat flux. The area between inlet and separation was found to be the most significant area for heat transfer. Radial distributions of azimuthal velocity and temperature are presented for various angles beginning at the inlet. Inner sphere pressure distribution is presented and the effect on flow separation is discussed.
Numerical Methods for Analysis of Charged Vacancy Diffusion in Dielectric Solids
2006-12-01
H. A.; Wilkes, J. O. Applied Numerical Methods ; Wiley: New York, 1969. Chapra , S. C.; Canale, R. P. Numerical Methods for Engineers with... Numerical Methods for Analysis of Charged Vacancy Diffusion in Dielectric Solids by John D. Clayton, Peter W. Chung, Michael A. Greenfield...Proving Ground, MD 21005-5066 ARL-TR-4002 December 2006 Numerical Methods for Analysis of Charged Vacancy Diffusion in Dielectric Solids
Numerical Analysis of Impulse Turbine for Isolated Pilot OWC System
Zhen Liu
2013-01-01
Full Text Available Oscillating water column (OWC is the most widely used wave energy converting technology in the world. The impulse turbine is recently been employed as the radial turbine in OWC facilities to convert bidirectional mechanical air power into electricity power. 3D numerical model for the impulse turbine is established in this paper to investigate its operating performance of the designed impulse turbine for the pilot OWC system which is under the construction on Jeju Island, Republic of Korea. The proper mesh style, turbulence model, and numerical solutions are employed to study the velocity and air pressure distribution especially around the rotor blade. The operating coefficients obtained from the numerical simulation are compared with corresponding experimental data, which demonstrates that the 3D numerical model proposed here can be applied to the research of impulse turbines for OWC system. Effects of tip clearances on flow field distribution characteristics and operating performances are also studied.
Experimental and Numerical Analysis of Steel Joints in Round Wood
Mikolášek David
2014-12-01
Full Text Available The paper analyses a drawn steel joint in round logs for which several types of reinforcements have been proposed. The load-carrying capacity of the reinforcements have been tested in laboratories. At the same time, numerical modelling has been performed - it has focused, in particular, on rigidity of the joints during the loading process. Physical and geometrical nonlinearities have been taken into account. The Finite Element Method and 3D computation models have been used in the numerical calculations.
Mathematical Theory of Compressible Viscous Fluids: Analysis and Numerics
Feireisl, E. (Eduard); Karper, T.; Pokorný, M.
2016-01-01
This book offers an essential introduction to the mathematical theory of compressible viscous fluids. The main goal is to present analytical methods from the perspective of their numerical applications. Accordingly, we introduce the principal theoretical tools needed to handle well-posedness of the underlying Navier-Stokes system, study the problems of sequential stability, and, lastly, construct solutions by means of an implicit numerical scheme. Offering a unique contribution – by exploring...
Wang, H; Sun, C; Peng, X X
2001-07-01
Two plant expression vectors(pBinPRHbI and pBinPRSIHbI) were constructed: Firstly, apidaecin gene were fused to the signal peptide coding sequencing of a PR-protein, and cloned into a binary vector pBin438 to form pBinPRHbI. Then, the cassette consisting of 35S promoter, PR signal peptide coding sequencing and apidaecin gene was cut off from pBinPRHbI and inserted into another plant expression vector pBinPRSI to produce a bivalent plant expression vector pBinPRSIHbI. pBinPRSI was constructed previously in our lab and contained PR signal peptide and Shiva-I fusion gene under control of 35S promoter. The three plant expression vectors were introduced into tobacco by Agrobacterium-mediated transformation. The positive rate of PCR was 95% in all putative transgenic plants. Results from Southern blot indicated that foreign genes were integrated into tobacco genome and RT-PCR analysis proved that the foreign gene was transcribed in transgenic tobacco. The transgenic tobacco showed higher resistance to P. syringae pv tabaci, the causal agent of tobacco wild fire disease, than their original cultivars. From the disease index, the transgenic plants carrying apidaecin and Shiva-I genes had highest resistance among three kinds of transgenic plants, and the plants carrying Shiva-I gene alone had lowest resistance.
Isabela Pereira de Oliveira
2016-02-01
Full Text Available The goal of the present study was to evaluate the spatial distribution of American cutaneous leishmaniasis (ACL in Seropédica, Rio de Janeiro State, Brazil according to the favorability of occurrence. The Vista-SAGA Geo-environmental Analysis System (Sistema de Análise Geoambiental Vista-SAGA was used to create a database (theme maps and perform environmental analyses, signatures and combinations. The degrees of likelihood were obtained by evaluating soil use and plant cover; soil type and geomorphology (geo-environmental factors; and altitude and slope (topographic factors. The factors used in the analyses were selected based on results from the literature and according to the technical feasibility of their inclusion in the databases. Weights and grades were attributed to the factors and their categories, respectively, according to their relevance to the life cycle of parasites from genus Leishmania and parasite vectors. Based on the results of the environmental analyses, areas were classified and grouped to represent the spatial distribution of favorability. Areas were classified as very unfavorable, unfavorable, somewhat favorable, favorable and very favorable for ACL occurrence. The results of the signature analyses showed that the municipality included 6.81% very favorable areas, 65.14% favorable areas, 17.98% somewhat favorable areas, 2.39% unfavorable areas and 0.07% very unfavorable areas for ACL occurrence. The signature analyses of the results and theme maps were able to locate and characterize the ecosystem profiles in terms of risk of ACL occurrence, indicating that rural, peri-urban and urban areas of the municipality of Seropédica may be classified as favorable for the occurrence of this disease. The results of the present study may be used to support management decisions made by authorities responsible for ACL control and prevention in Seropédica. In addition, geoprocessing was found to be a low-cost alternative for data
Musser, Richard O; Hum-Musser, Sue M; Gallucci, Matthew; DesRochers, Brittany; Brown, Judith K
2014-01-01
Plants are routinely exposed to biotic and abiotic stresses to which they have evolved by synthesizing constitutive and induced defense compounds. Induced defense compounds are usually made, initially, at low levels; however, following further stimulation by specific kinds of biotic and abiotic stresses, they can be synthesized in relatively large amounts to abate the particular stress. cDNA microarray hybridization was used to identify an array of genes that were differentially expressed in tomato plants 15 d after they were exposed to feeding by nonviruliferous whiteflies or by viruliferous whiteflies carrying Pepper golden mosaic virus (PepGMV) (Begomovirus, Geminiviridae). Tomato plants inoculated by viruliferous whiteflies developed symptoms characteristic of PepGMV, whereas plants exposed to nonviruliferous whitefly feeding or nonwounded (negative) control plants exhibited no disease symptoms. The microarray analysis yielded over 290 spotted probes, with significantly altered expression of 161 putative annotated gene targets, and 129 spotted probes of unknown identities. The majority of the differentially regulated "known" genes were associated with the plants exposed to viruliferous compared with nonviruliferous whitefly feeding. Overall, significant differences in gene expression were represented by major physiological functions including defense-, pathogen-, photosynthesis-, and signaling-related responses and were similar to genes identified for other insect-plant systems. Viruliferous whitefly-stimulated gene expression was validated by real-time quantitative polymerase chain reaction of selected, representative candidate genes (messenger RNA): arginase, dehydrin, pathogenesis-related proteins 1 and -4, polyphenol oxidase, and several protease inhibitors. This is the first comparative profiling of the expression of tomato plants portraying different responses to biotic stress induced by viruliferous whitefly feeding (with resultant virus infection
Numerical modeling and analysis of the active magnetic regenerator
Nielsen, Kaspar Kirstein
expressed as temperature span versus cooling power is mapped as a function of the central parameters. Since regenerators built of several magnetic materials distinguished by their respective magnetic transition temperatures are reported to perform better than single-material AMRs this concept has been......In this thesis the active magnetic regenerator (AMR) is analyzed using various numerical tools and experimental devices. A 2-dimensional transient numerical model of the AMR is developed and implemented and it is used to investigate the in uence of a range of parameters on the performance...... investigated using the numerical AMR model. The results show indeed that the performance may be enhanced signicantly and it may thus be concluded that the performance of the AMR is dependent on a vast number of parameters (material composition, magnetic eld source, regenerator geometry, regenerator eciency...
Prey capture by harbor porpoises
Miller, Lee; Verfuss, Ursula
2009-01-01
The harbor porpoise (Phocoena phocoena) is a small toothed whale living mostly in coastal waters. There are large, but unknown, numbers in the inner Danish waters. Four are in captivity at Fjord & Bælt, Kerteminde, Denmark, one of which was born here in 2006. Harbor porpoises use their ultraso...
International Winter Workshop on Differential Equations and Numerical Analysis
Miller, John; Narasimhan, Ramanujam; Mathiazhagan, Paramasivam; Victor, Franklin
2016-01-01
This book offers an ideal introduction to singular perturbation problems, and a valuable guide for researchers in the field of differential equations. It also includes chapters on new contributions to both fields: differential equations and singular perturbation problems. Written by experts who are active researchers in the related fields, the book serves as a comprehensive source of information on the underlying ideas in the construction of numerical methods to address different classes of problems with solutions of different behaviors, which will ultimately help researchers to design and assess numerical methods for solving new problems. All the chapters presented in the volume are complemented by illustrations in the form of tables and graphs.
Analysis of anelastic flow and numerical treatment via finite elements
Martinez, M.J.
1994-05-01
In this report, we reconsider the various approximations made to the full equations of motion and energy transport for treating low-speed flows with significant temperature induced property variations. This entails assessment of the development of so-called anelastic for low-Mach number flows outside the range of validity of the Boussinesq equations. An integral part of this assessment is the development of a finite element-based numerical scheme for obtaining approximate numerical solutions to this class of problems. Several formulations were attempted and are compared.
Numerical Analysis of Turbulent Flows in Channels of Complex Geometry
Farbos De Luzan, Charles
The current study proposes to follow a systematic validated approach to applied fluid mechanics problems in order to evaluate the ability of different computational fluid dynamics (CFD) to be a relevant design tool. This systematic approach involves different operations such as grid sensitivity analyses, turbulence models comparison and appropriate wall treatments, in order to define case-specific optimal parameters for industrial applications. A validation effort is performed on each study, with particle image velocimetry (PIV) experimental results as the validating metric. The first part of the dissertation lays down the principles of validation, and presents the details of a grid sensitivity analysis, as well as a turbulence models benchmark. The models are available in commercial solvers, and in most cases the default values of the equations constants are retained. The validation experimental data is taken with a hot wire, and has served as a reference to validate multiple turbulence models for turbulent flows in channels. In a second part, the study of a coaxial piping system will compare a set of different steady Reynolds-Averaged Navier Stokes (RANS) turbulence models, namely the one equation model Spalart-Almaras, and two-equation-models standard k-epsilon, k-epsilon realizable, k-epsilon RNG, standard k-omega, k-omega SST, and transition SST. The geometry of interest involves a transition from an annulus into a larger one, where highly turbulent phenomena occur, such as recirculation and jet impingement. Based on a set of constraints that are defined in the analysis, a chosen model will be tested on new designs in order to evaluate their performance. The third part of this dissertation will address the steady-state flow patterns in a Viscosity-Sensitive Fluidic Diode (VSFD). This device is used in a fluidics application, and its originality lies in the fact that it does not require a control fluid in order to operate. This section will discuss the
Sensible Heat Transfer during Droplet Cooling: Experimental and Numerical Analysis
Emanuele Teodori
2017-06-01
Full Text Available This study presents the numerical reproduction of the entire surface temperature field resulting from a water droplet spreading on a heated surface, which is compared with experimental data. High-speed infrared thermography of the back side of the surface and high-speed images of the side view of the impinging droplet were used to infer on the solid surface temperature field and on droplet dynamics. Numerical reproduction of the phenomena was performed using OpenFOAM CFD toolbox. An enhanced volume of fluid (VOF model was further modified for this purpose. The proposed modifications include the coupling of temperature fields between the fluid and the solid regions, to account for transient heat conduction within the solid. The results evidence an extremely good agreement between the temporal evolution of the measured and simulated spreading factors of the considered droplet impacts. The numerical and experimental dimensionless surface temperature profiles within the solid surface and along the droplet radius, were also in good agreement. Most of the differences were within the experimental measurements uncertainty. The numerical results allowed relating the solid surface temperature profiles with the fluid flow. During spreading, liquid recirculation within the rim, leads to the appearance of different regions of heat transfer that can be correlated with the vorticity field within the droplet.
Numerical analysis of elastic coated solids in line contact
王廷剑; 王黎钦; 古乐; 赵小力
2015-01-01
A line contact model of elastic coated solids is presented based on the influence coefficients (ICs) of surface displacement and stresses of coating−substrate system and the traditional contact model. The ICs of displacement and stresses are obtained from their corresponding frequency response functions (FRF) by using a conversion method based on fast Fourier transformation (FFT). The contact pressure and the stress field in the subsurface are obtained by employing conjugate gradient method (CGM) and discrete convolution fast Fourier transformation (DC-FFT). Comparison of the contact pressure and subsurface stresses obtained by the numerical method with the exact analytical solutions for Hertz contact is conducted, and the results show that the numerical solution has a very high accuracy and verify the validity of the contact model. The effect of the stiffness and thickness of coatings is further numerically studied. The result shows that the effects on contact pressure and contact width are opposite for hard and soft coatings and are intensified with the increase of coating thickness; the locations of crack initiation and propagation are different for soft and hard coatings; the risk of cracks and delaminations of coatings can be brought down by improving the lubrication condition or optimizing the non-dimensional parameterh/bh. This research offers a tool to numerically analyze the problem of elastic coated solids in line contact and make the blindness and randomness of trial-type coating design less.
Introduction to Numerical Computation - analysis and Matlab illustrations
Elden, Lars; Wittmeyer-Koch, Linde; Nielsen, Hans Bruun
In a modern programming environment like eg MATLAB it is possible by simple commands to perform advanced calculations on a personal computer. In order to use such a powerful tool efiiciently it is necessary to have an overview of available numerical methods and algorithms and to know about...... are illustrated by examples in MATLAB....
Numerical Analysis on Rotary Forging Mechanism of a Flange
无
2001-01-01
A numerical simulation on the rotary forging process of a flange is conducted by three-dimensional rigid-plastic finite element method. The states of stress and strain rate in the workpiece are analyzed and the forging mechanism of the flange is revealed. Moreover, the influence of the die configuration on the material flow is also analyzed.
Numerical Tools for the Bayesian Analysis of Stochastic Frontier Models
Osiewalski, J.; Steel, M.F.J.
1996-01-01
In this paper we describe the use of modern numerical integration methods for making posterior inferences in composed error stochastic frontier models for panel data or individual cross-sections.Two Monte Carlo methods have been used in practical applications.We survey these two methods in some
Numerical analysis of fragmentation mechanisms in vapor explosions
Koshizuka, Seiichi; Ikeda, Hirokazu; Oka, Yoshiaki [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.
1998-01-01
Fragmentation of molten metal is the key process in vapor explosions. However this process is so rapid that the mechanisms have not been clarified yet in the experimental studies. Besides, numerical simulation is difficult because we have to analyze water, steam and molten metal simultaneously with evaporation and fragmentation. The authors have been developing a new numerical method, the Moving Particle Semi-implicit (MPS) method, based on moving particles and their interactions. Grids are not necessary. Incompressible flows with fragmentation on free surfaces have been calculated successfully using the MPS method. In the present study numerical simulation of the fragmentation processes using the MPS method is carried out to investigate the mechanisms. A numerical model to calculate evaporation from water to steam is developed. In this model, new particles are generated on water-steam interfaces. Effect of evaporation is also investigated. Growth of the filament is not accelerated when the normal evaporation is considered. This is because the normal evaporation needs a longer time than the moment of the jet impingement, though the filament growth is decided in this moment. Next, rapid evaporation based on spontaneous nucleation is considered. The filament growth is markedly accelerated. This result is consistent with the experimental fact that the spontaneous nucleation temperature is a necessary condition of small-scale vapor explosions. (J.P.N.)
Numerical analysis of time-dependent Boussinesq models
Houwen, P.J. van der; Mooiman, J.; Wubs, F.W.
1991-01-01
In this paper we analyse numerical models for time-dependent Boussinesq equations. These equations arise when so-called Boussinesq terms are introduced into the shallow water equations. We use the Boussinesq terms proposed by Katapodes and Dingemans. These terms generalize the constant depth terms g
Bo Liu
Full Text Available BACKGROUND: Although cold shock responses and the roles of cold shock proteins in microorganisms containing multiple cold shock protein genes have been well characterized, related studies on bacteria possessing a single cold shock protein gene have not been reported. Thermoanaerobacter tengcongensis MB4, a thermophile harboring only one known cold shock protein gene (TtescpC, can survive from 50° to 80 °C, but has poor natural competence under cold shock at 50 °C. We therefore examined cold shock responses and their effect on natural competence in this bacterium. RESULTS: The transcriptomes of T. tengcongensis before and after cold shock were analyzed by RNA-seq and over 1200 differentially expressed genes were successfully identified. These genes were involved in a wide range of biological processes, including modulation of DNA replication, recombination, and repair; energy metabolism; production of cold shock protein; synthesis of branched amino acids and branched-chain fatty acids; and sporulation. RNA-seq analysis also suggested that T. tengcongensis initiates cell wall and membrane remodeling processes, flagellar assembly, and sporulation in response to low temperature. Expression profiles of TtecspC and failed attempts to produce a TtecspC knockout strain confirmed the essential role of TteCspC in the cold shock response, and also suggested a role of this protein in survival at optimum growth temperature. Repression of genes encoding ComEA and ComEC and low energy metabolism levels in cold-shocked cells are the likely basis of poor natural competence at low temperature. CONCLUSION: Our study demonstrated changes in global gene expression under cold shock and identified several candidate genes related to cold shock in T. tengcongensis. At the same time, the relationship between cold shock response and poor natural competence at low temperature was preliminarily elucidated. These findings provide a foundation for future studies on genetic
Numerical analysis of nanostructures for enhanced light extraction from OLEDs
Zschiedrich, L; Burger, S; Schmidt, F; 10.1117/12.2001132
2013-01-01
Nanostructures, like periodic arrays of scatters or low-index gratings, are used to improve the light outcoupling from organic light-emitting diodes (OLED). In order to optimize geometrical and material properties of such structures, simulations of the outcoupling process are very helpful. The finite element method is best suited for an accurate discretization of the geometry and the singular-like field profile within the structured layer and the emitting layer. However, a finite element simulation of the overall OLED stack is often beyond available computer resources. The main focus of this paper is the simulation of a single dipole source embedded into a twofold infinitely periodic OLED structure. To overcome the numerical burden we apply the Floquet transform, so that the computational domain reduces to the unit cell. The relevant outcoupling data are then gained by inverse Flouqet transforming. This step requires a careful numerical treatment as reported in this paper.
Numerical analysis of bump foil bearings without nominal radial clearance
LIU Zhan-sheng; XU Huai-jin; ZHANG Guang-hui
2008-01-01
Bump foil bearings without nominal radial clearance were analyzed. An air film thickness model and a bearing theoretical analytical model were developed accounting for air compressibility and foil deformation. To analyze hydrodynamic characteristics of bump foil beatings with different operating eccentricities, the air film thickness equation and Reynolds equation were coupled through pressure and solved by Newton-Raphson Method(NRM) and Finite Difference Method (FDM). The characteristics of an bump foil bearing model were dis-cussed including load carrying capacity, film thickness and pressure distributions. The results of simulation show that bump foil beating without nominal radial clearance can provide better stability and greater load capaci-ty. This numerical analytical method also reveals a good convergence in numerical calculation.
Numerical analysis of microholes film/effusion cooling effectiveness
Ochrymiuk, Tomasz
2017-10-01
Numerical simulations were performed to predict the film cooling effectiveness on the fiat plate with a three-dimensional discrete hole film cooling RSM-AKN turbulent heat transfer models based on variable turbulent Prandtl number approaches were considered. Obtained numerical results were directly compared with the data that came from an experiment based on Transient Liquid Crystal methodology. All implemented models for turbulent heat transfer performed sufficiently well for the considered case. It was confirmed, however, that the two-equation closure can give a detailed look into film cooling problems without using any time-consuming and inherently unsteady models. The RSM-AKN turbulent model was used in micoholes case too. The main target of simulations was maintain the same level of cooling efficiency ratio in both cases and confirm that is possible significantly reduce mass flows of the coolant in microholes case.
3D numerical simulation and analysis of railgun gouging mechanism
Jin-guo WU; Bo TANG; Qing-hua LIN; Hai-yuan LI; Bao-ming LI
2016-01-01
A gouging phenomenon with a hypervelocity sliding electrical contact in railgun not only shortens the rail lifetime but also affects the interior ballistic performance. In this paper, a 3-D numerical model was introduced to simulate and analyze the generation mechanism and evolution of the rail gouging phenomenon. The results show that a rail surface bulge is an important factor to induce gouging. High density and high pressure material flow on the contact surface, obliquely extruded into the rail when accelerating the armature to a high velocity, can produce gouging. Both controlling the bulge size to a certain range and selecting suitable materials for rail surface coating will suppress the formation of gouging. The numerical simulation had a good agreement with experiments, which validated the computing model and methodology are reliable.
An Experimental and Numerical Analysis of Puff Hydrodynamics
Saidi MS
2014-12-01
Full Text Available The permeability of a tobacco rod in a cigarette increases as it converts into char and ash in the coal. The hot coal introduces a significant resistance to the air flow when air passes through. Through a series of experiments, the cigarette burn line and burn rate, the centerline temperature, and the pressure drop were measured for continuous puffing conditions. The gas viscosity was calculated from the temperature distribution inside the cigarette and applying Sutherland's law. Then, the experimental setup was mathematically modeled from a commercially available CFD (Computational Fluid Dynamics code and, by matching the numerical and experimental results, the changes in coal and filter permeability during puffing were estimated. The numerical simulation successfully reproduced the results of experiments on the air flow through the coal, ventilation holes and paper wrapper.
NUMERICAL ANALYSIS OF GASEOUS FLOW IN MICRO-CHANNELS
Xu Jie; Gu Chuangang; Wang Tong
2004-01-01
The algorithm of gaseous flow in bi-dimensional micro-channels is set up and the corresponding program based on micro-flow theory is presented. Gaseous flow in micro-channels is numerically analyzed and the pressure drop along the duct as well as the velocity profile in the micro-channels is obtained. The numerical results agreed well with the experimental results in the references. Moreover, the effects of Kn, (σv and Re on the velocity profiles are analyzed. It is found that for Kn>0.001, with increasing Kn number, the slip velocity on the wall boundary increases; the tangential momentum coefficient (σv affects the slip velocity greatly. The slip velocity increases with decreasing (σv In the slip flow regime and for low Re numbers, the slip velocity is little influenced by the Re number.
Numerical analysis of quench in coated conductors with defects
Liu, Wenbin; Yong, Huadong; Zhou, Youhe
2016-09-01
When the superconductor is subjected to local thermal perturbations, a large amount of joule heat may be generated in the conductor, which may lead to a quench. In a quench event, a normal zone irreversibly spreads throughout the conductor leading to failure of the superconducting device. In this paper, we will discuss the one-dimensional quench behavior in the coated conductors with internal defects or interface defects. Based on the numerical procedure given in the previous works, the normal zone propagation is studied by using the finite difference method. The numerical results are presented to discuss the normal zone propagation. We consider the effect of internal defect on the nonuniform temperature propagation. For the conductor with interface defects, it can be found that the normal zone propagation velocity is increased by defects.
Numerical analysis of quench in coated conductors with defects
Wenbin Liu
2016-09-01
Full Text Available When the superconductor is subjected to local thermal perturbations, a large amount of joule heat may be generated in the conductor, which may lead to a quench. In a quench event, a normal zone irreversibly spreads throughout the conductor leading to failure of the superconducting device. In this paper, we will discuss the one-dimensional quench behavior in the coated conductors with internal defects or interface defects. Based on the numerical procedure given in the previous works, the normal zone propagation is studied by using the finite difference method. The numerical results are presented to discuss the normal zone propagation. We consider the effect of internal defect on the nonuniform temperature propagation. For the conductor with interface defects, it can be found that the normal zone propagation velocity is increased by defects.
Numerical analysis of capacitive pressure micro-sensors
WANG; Xiaomin; LI; Mingxuan; WANG; Chenghao
2005-01-01
Pseudo-spectral method is used to numerically model the diaphragm deflection of capacitive pressure micro-sensor under uniform load. The relationship between the capacitance of the micro-sensor and the load is then analyzed after the description of the computational principle. For normal mode micro-sensor, the tensile force on the diaphragm can be ignored and thereby the capacitance increases linearly with the load increase only when the load is so small that the resultant deflection is less than the diaphragm thickness. The linear relationship between the capacitance and the load turns to be nonlinear thereafter and the capacitance rises dramatically with the constant increase of the load. For touch mode micro-sensor, an algorithm to determine the touch radius of the diaphragm and substrate is presented and the curve of capacitance versus load is shown on the numerical results laying a theoretical foundation for micro-sensor design.
A general numerical analysis of time-domain NQR experiments.
Harel, Elad; Cho, Herman
2006-12-01
We introduce a general numerical approach for solving the Liouville equation of an isolated quadrupolar nuclide that can be used to analyze the unitary dynamics of time-domain NQR experiments. A numerical treatment is necessitated by the dimensionality of the Liouville space, which precludes analytical, closed form solutions for I > 3/2. Accurate simulations of experimental nutation curves, forbidden transition intensities, powder and single crystal spectra, and off-resonance irradiation dynamics can be computed with this method. We also examine the validity of perturbative approximations where the signal intensity of a transition is proportional to the transition moment between the eigenstates of the system, thus providing a simple basis for determining selection rules. Our method allows us to calculate spectra for all values of the asymmetry parameter, eta, and sample orientations relative to the coil axis. We conclude by demonstrating the methodology for calculating the response of the quadrupole system to amplitude- and frequency-modulated pulses.
The Numerical Analysis of Flow Field on Warship Deck
Kwan Ouyang
2015-03-01
Full Text Available This study aims to simulate the exhaust flow field of ship by the method of computational fluid dynamics (CFD concerning with the interference by exhaust temperature, shape of stack and rolling angles etc.. In this research wind tunnel test for a corvette has been performed to attain associated experimental data, which were used as a reference basis. During simulation process several configurations of stacks have been selected, and combining with various rolling angles, exhaust temperatures and velocities, we have generated numerous cases from which the diffusion paths and temperature distribution of the exhaust flow field can be clearly observed and analyzed. In terms of numerical simulation, the packaged program computational fluid dynamics software has been adopted. The simulation results also possess the same trend as the experimental data, which have initially confirmed the methods developed here can be used for the arrangement of stack and superstructure at the stage of initial and conceptual design of ships.
3D numerical simulation and analysis of railgun gouging mechanism
Jin-guo Wu
2016-04-01
Full Text Available A gouging phenomenon with a hypervelocity sliding electrical contact in railgun not only shortens the rail lifetime but also affects the interior ballistic performance. In this paper, a 3-D numerical model was introduced to simulate and analyze the generation mechanism and evolution of the rail gouging phenomenon. The results show that a rail surface bulge is an important factor to induce gouging. High density and high pressure material flow on the contact surface, obliquely extruded into the rail when accelerating the armature to a high velocity, can produce gouging. Both controlling the bulge size to a certain range and selecting suitable materials for rail surface coating will suppress the formation of gouging. The numerical simulation had a good agreement with experiments, which validated the computing model and methodology are reliable.
Analytical Analysis and Numerical Solution of Two Flavours Skyrmion
Hadi, Miftachul; Hermawanto, Denny
2010-01-01
Two flavours Skyrmion will be analyzed analytically, in case of static and rotational Skyrme equations. Numerical solution of a nonlinear scalar field equation, i.e. the Skyrme equation, will be worked with finite difference method. This article is a more comprehensive version of \\textit{SU(2) Skyrme Model for Hadron} which have been published at Journal of Theoretical and Computational Studies, Volume \\textbf{3} (2004) 0407.
Numerical analysis and geotechnical assessment of mine scale model
Khanal Manoj; Adhikary Deepak; Balusu Rao
2012-01-01
Various numerical methods are available to model,simulate,analyse and interpret the results; however a major task is to select a reliable and intended tool to perform a realistic assessment of any problem.For a model to be a representative of the realistic mining scenario,a verified tool must be chosen to perform an assessment of mine roof support requirement and address the geotechnical risks associated with longwall mining.The dependable tools provide a safe working environment,increased production,efficient management of resources and reduce environmental impacts of mining.Although various methods,for example,analytical,experimental and empirical are being adopted in mining,in recent days numerical tools are becoming popular due to the advancement in computer hardware and numerical methods.Empirical rules based on past experiences do provide a general guide,however due to the heterogeneous nature of mine geology (i.e.,none of the mine sites are identical),numerical simulations of mine site specific conditions would lend better insights into some underlying issues.The paper highlights the use of a continuum mechanics based tool in coal mining with a mine scale model.The continuum modelling can provide close to accurate stress fields and deformation.The paper describes the use of existing mine data to calibrate and validate the model parameters,which then are used to assess geotechnical issues related with installing a new high capacity longwall mine at the mine site.A variety of parameters,for example,chock convergences,caveability of overlying sandstones,abutment and vertical stresses have been estimated.
Numerical Analysis of Turbocharger’s Bearing using Dynamic Mesh
J. Moradi Cheqamahi
2016-01-01
Full Text Available Journal bearings are widely used in different machineries. Reynolds equation is the governing equation to predict pressure distribution and load bearing capacity in journal bearings. There are many analytical and numerical methods for solving this equation. The main disadvantage of these methods is their inability to analyze complex geometries. In this paper, a comprehensive method based on dynamic mesh method is developed to solve the conservation equations of mass, momentum and energy. This method has smaller error compared to other techniques. To verify the accuracy of this method, the bearings with different length to diameter ratios are analytically and numerically analyzed under different loads and compared with each other. In continue, the turbocharger’s bearing is numerically simulated and the effects of rotational speed change are studied. Finally, the turbocharger’s bearing with four axial grooves are simulated. The simulations results show that adding grooves to the turbocharger’s bearing causes the bearing eccentricity ratio and lubricant flow rate to increase and the attitude angle, rate of temperature rise and frictional torque to decrease.
Numerical bifurcation analysis of the bipedal spring-mass model
Merker, Andreas; Kaiser, Dieter; Hermann, Martin
2015-01-01
The spring-mass model and its numerous extensions are currently one of the best candidates for templates of human and animal locomotion. However, with increasing complexity, their applications can become very time-consuming. In this paper, we present an approach that is based on the calculation of bifurcations in the bipedal spring-mass model for walking. Since the bifurcations limit the region of stable walking, locomotion can be studied by computing the corresponding boundaries. Originally, the model was implemented as a hybrid dynamical system. Our new approach consists of the transformation of the series of initial value problems on different intervals into a single boundary value problem. Using this technique, discontinuities can be avoided and sophisticated numerical methods for studying parametrized nonlinear boundary value problems can be applied. Thus, appropriate extended systems are used to compute transcritical and period-doubling bifurcation points as well as turning points. We show that the resulting boundary value problems can be solved by the simple shooting method with sufficient accuracy, making the application of the more extensive multiple shooting superfluous. The proposed approach is fast, robust to numerical perturbations and allows determining complete manifolds of periodic solutions of the original problem.
Numerical Analysis on Combustion Characteristic of Leaf Spring Rotary Engine
Yan Zhang
2015-08-01
Full Text Available The purpose of this paper is to investigate combustion characteristics for rotary engine via numerical studies. A 3D numerical model was developed to study the influence of several operative parameters on combustion characteristics. A novel rotary engine called, “Leaf Spring Rotary Engine”, was used to illustrate the structure and principle of the engine. The aims are to (1 improve the understanding of combustion process, and (2 quantify the influence of rotational speed, excess air ratio, initial pressure and temperature on combustion characteristics. The chamber space changed with crankshaft rotation. Due to the complexity of chamber volume, an equivalent modeling method was presented to simulate the chamber space variation. The numerical simulations were performed by solving the incompressible, multiphase Unsteady Reynolds-Averaged Navier–Stokes Equations via the commercial code FLUENT using a transport equation-based combustion model; a realizable turbulence model and finite-rate/eddy-dissipation model were used to account for the effect of local factors on the combustion characteristics.
Senger, Karen
2012-01-01
Purpose: The purposes of this study were to investigate and describe how elementary teachers in exited Program Improvement-Safe Harbor schools acquire student achievement data through assessments, the strategies and reflections utilized to make sense of the data to improve student achievement, ensure curriculum and instructional goals are aligned,…
Senger, Karen
2012-01-01
Purpose: The purposes of this study were to investigate and describe how elementary teachers in exited Program Improvement-Safe Harbor schools acquire student achievement data through assessments, the strategies and reflections utilized to make sense of the data to improve student achievement, ensure curriculum and instructional goals are aligned,…
Orange County Littoral Cell CRSMP Harbor Receiver Sites 2012
California Department of Resources — Harbor reciever sites from Everest (2009) 'Harbor Area Management Plan, In-Harbor Beach Replenishment Strategy', Technical Report. Prepared for Harbor Resources...
Grandinetti, Lucio; Purnama, Anton
2015-01-01
Presenting the latest findings in the field of numerical analysis and optimization, this volume balances pure research with practical applications of the subject. Accompanied by detailed tables, figures, and examinations of useful software tools, this volume will equip the reader to perform detailed and layered analysis of complex datasets. Many real-world complex problems can be formulated as optimization tasks. Such problems can be characterized as large scale, unconstrained, constrained, non-convex, non-differentiable, and discontinuous, and therefore require adequate computational methods, algorithms, and software tools. These same tools are often employed by researchers working in current IT hot topics such as big data, optimization and other complex numerical algorithms on the cloud, devising special techniques for supercomputing systems. The list of topics covered include, but are not limited to: numerical analysis, numerical optimization, numerical linear algebra, numerical differential equations, opt...
Numerical and experimental analysis of vertical spray control patternators
F. Sarghini
2013-09-01
Full Text Available The experimental vertical spray control walls have the purpose of picking up the liquid delivered by trained sprayer for providing the liquid distribution profile in height. Theoretically this should correspond to the ideal profile, which consists in a uniform distribution on the vegetation. If the profile is different from the ideal, a parameter setup is required on the sprayer. Nonetheless, some problems are hidden in the aforementioned statements: i no wall measures exactly the distribution profile (i.e. the flow through the sections in the vertical plane, parallel to the direction of advancement of the sprayer. Compared to real profile, sensitive errors are introduced: the evaporation of the drops, the deviation of the air flows caused by the sensors panel themselves; by the possibility that the drops bounce on the wall panels, also due to the current of air that can push the liquid veil laterally or upwards, Moreover, everything varies depending on the geometry of the sensors, air velocity, air humidity; ii no one knows what exactly is the optimal distribution profile. It is often considered as optimal a profile that reflects the amount of leaf area subtended by each section absorber: however, it is evident that the path of the droplets changes according to the sprayer typology (eg. radial-flow or horizontal flows. In this work a combined numerical-experimental approach is adopted, in order to assess some of the aforementioned issues: numerical data obtained by using computational fluid dynamics models are compared and validated with experimental data, in order to assess the reliability of numerical simulations in configurations which are difficult to analyze using an experimental setup.
Numerical Analysis of Secondary Cooling in Continuous Slab Casting
Kee-Hyeon Cho; Byung-Moon Kim
2008-01-01
In the present study, a numerical optimization program has been developed for predicting the optimal secondary cooling patterns in a continuous slab caster. Optimization strategy using Broydon-Fletcher-Goldfarb-Shanno (BFGS) method is carried out by determining the constant heat transfer coefficients in each spray zone, which could satisfy the casting conditions and metallurgical criteria specified by the engineer. From the present results, it is found that even a slight variation in the pouring temperature, allowable surface temperature, and casting speed could give rise to the changes in the cooling pattern throughout the spray zones.
Numerical analysis of soil bearing capacity by changing soil characteristics
Mehdi Khodashenas Pelko
2009-10-01
Full Text Available In this research work by changing different parameters of soil foundation like density, cohesion and foundation depth and width of square foundation at angle of friction of 0° to 50° with increment of 5°, numerically safe bearing capacity of soil foundation is calculated and it is attempted to assess economical dimension of foundation as well as understanding variation range of bearing capacity at different degree. It could help of civil engineering in design of foundations at any situation.
Floor Heating with Displacement Ventilation: An Experimental and Numerical Analysis
Causone, Francesco; Olesen, Bjarne W.; Corgnati, S.P.
2010-01-01
The effect of floor heating combined with displacement ventilation (DV) on thermal indoor environments and indoor air quality (IAQ) was studied by means of CFD. The numerical model was validated with experimental data. A typical office room was simulated, and one of the occupants was considered...... to simulate different kinds of contaminant sources, under the same boundary conditions. It was found that DV does not guarantee a better IAQ than full mixing when contaminant sources are not linked to heat sources, even when floor heating is used. Contaminants produced by powerful heat sources require high...
Connecting Numerical Relativity and Data Analysis of Gravitational Wave Detectors
Shoemaker, Deirdre; London, Lionel; Pekowsky, Larne
2015-01-01
Gravitational waves deliver information in exquisite detail about astrophysical phenomena, among them the collision of two black holes, a system completely invisible to the eyes of electromagnetic telescopes. Models that predict gravitational wave signals from likely sources are crucial for the success of this endeavor. Modeling binary black hole sources of gravitational radiation requires solving the Eintein equations of General Relativity using powerful computer hardware and sophisticated numerical algorithms. This proceeding presents where we are in understanding ground-based gravitational waves resulting from the merger of black holes and the implications of these sources for the advent of gravitational-wave astronomy.
Numerical analysis of welded joint treated by explosion shock waves
GUAN Jianjun; CHEN Huaining
2007-01-01
This paper focuses on the simulation of welding residual stresses and the action of explosion shock waves on welding residual stresses. Firstly, the distributions of welding temperature field and residual stress on a butt joint were numerically simulated with the sequentially coupled method. Secondly, the effect of explosion shock waves, produced by plastic strip-like explosive, on welding residual stress distri-bution was predicted with coupled Lagrange-ALE algorithm.It was implicated that explosion treatment could effectively reduce welding residual stresses. The simulation work lays a foundation for the further research on the rule of explosion treatment's effect on welding residual stresses and the factors that may influence it.
Numerical simulation and mechanism analysis of freak waves
无
2007-01-01
A numerical wave model based on the modified fourth-order nonlinear Schroe dinger equation (mNLSE) in deep water was developed to simulate the formation of freak waves and a standard split-step, pseudo-spectral method was used to solve the equation. The validation of the model is firstly verified, then the simulation of freak waves was performed by changing sideband conditions, and the variation of wave energy was also analyzed in the evolution. The results indicate that Benjamin-Feir instability (sideband instability) is an important mechanism for freak wave formation.
Numerical Analysis of Transient Temperature Response of Soap Film
Tanaka, Seiichi; Tatesaku, Akihiro; Dantsuka, Yuki; Fujiwara, Seiji; Kunimine, Kanji
2015-11-01
Measurements of thermophysical properties of thin liquid films are important to understand interfacial phenomena due to film structures composed of amphiphilic molecules in soap film, phospholipid bilayer of biological cell and emulsion. A transient hot-wire technique for liquid films less than 1 \\upmu m thick such as soap film has been proposed to measure the thermal conductivity and diffusivity simultaneously. Two-dimensional heat conduction equations for a solid cylinder with a liquid film have been solved numerically. The temperature of a thin wire with liquid film increases steeply with its own heat generation. The feasibility of this technique is verified through numerical experiments for various thermal conductivities, diffusivities, and film thicknesses. Calculated results indicate that the increase in the volumetric average temperature of the thin wire sufficiently varies with the change of thermal conductivity and diffusivity of the soap film. Therefore, the temperature characteristics could be utilized to evaluate both the thermal conductivity and diffusivity using the Gauss-Newton method.
Numerical solution-space analysis of satisfiability problems
Mann, Alexander; Hartmann, A. K.
2010-11-01
The solution-space structure of the three-satisfiability problem (3-SAT) is studied as a function of the control parameter α (ratio of the number of clauses to the number of variables) using numerical simulations. For this purpose one has to sample the solution space with uniform weight. It is shown here that standard stochastic local-search (SLS) algorithms like average satisfiability (ASAT) exhibit a sampling bias, as does “Metropolis-coupled Markov chain Monte Carlo” (MCMCMC) (also known as “parallel tempering”) when run for feasible times. Nevertheless, unbiased samples of solutions can be obtained using the “ballistic-networking approach,” which is introduced here. It is a generalization of “ballistic search” methods and yields also a cluster structure of the solution space. As application, solutions of 3-SAT instances are generated using ASAT plus ballistic networking. The numerical results are compatible with a previous analytical prediction of a simple solution-space structure for small values of α and a transition to a clustered phase at αc≈3.86 , where the solution space breaks up into several non-negligible clusters. Furthermore, in the thermodynamic limit there are, even for α=4.25 close to the SAT-UNSAT transition αs≈4.267 , always clusters without any frozen variables. This may explain why some SLS algorithms are able to solve very large 3-SAT instances close to the SAT-UNSAT transition.
Validation of numerical codes for the analysis of plasma discharges
Albanese, R. (Univ. di Salerno, Dipt. di Ingegneria Elettronica, Fisciano (Italy)); Bottura, L. (NET Team, Garching (Germany)); Chiocchio, S. (NET Team, Garching (Germany)); Coccorese, E. (Univ. di Reggio Calabria, Ist. di Ingegneria Elettronica (Italy)); Gernhardt, J. (Max Planck IPP, Garching (Germany)); Gruber, O. (Max Planck IPP, Garching (Germany)); Fresa, R. (Univ. di Salerno, Dipt. di Ingegneria Elettronica, Fisciano (Italy)); Martone, R. (Univ. di Salerno, Dipt. di Ingegneria Elettronica, Fisciano (Italy)); Portone, A. (NET Team, Garching (Germany)); Seidel, U. (Max Planck IPP, Garching (Germany))
1994-01-01
Electromagnetic aspects in the design of ITER-like reactors call for an extensive use of complex and advanced numerical codes. For this reason a strong attention has been paid within the NET-Team to the code development. In particular, through a cooperation with some Italian universities, during the last years a number of numerical procedures were developed and integrated. In order to assess the code reliability and to gain confidence on their predictions for next generation ITER-like reactors, the validation of the codes against experiments has to be considered as a strict requirement. Aim of this paper is to give a comprehensive presentation of this problem in the light of the results of a campaign of validation runs. The main outcome of this work is that the computational procedures, which have been developed for the NET project and then extensively used also for ITER studies, can be considered as experimentally validated in a sufficiently wide range of cases of interest. In particular, computed values are compared with experimental measurements made during some typical ASDEX-Upgrade discharges. From the electromagnetic point of view, many features of this machine are common to the ITER concept, so that the results of the validation can reasonably be extended to the ITER case. (orig.)
Sediment toxicity in Savannah Harbor
US Fish and Wildlife Service, Department of the Interior — Savannah Harbor, located near the mouth of the Savannah River, Georgia and South Carolina, is impacted by industrial and municipal effluents. Contaminants released...
Alaska Harbor Seal Glacial Surveys
National Oceanic and Atmospheric Administration, Department of Commerce — Floating glacial ice serves as a haul-out substrate for a significant number (10-15%) of Alaskan harbor seals, and thus surveying tidewater glacial fjords is an...
无
2008-01-01
@@ 2007 China Harbor Ten People elected the entrepreneurs who contributed a lot to port economy and enterprises this year trough their talent management.These ten people embody their social responsibility,professional skills,creative ability,and charming personality.Bearing full confidence in China's port economy,the port entrepreneurs are brave enough to explore a brand new area,so as to promote harbor economic development.
Notes on numerical reliability of several statistical analysis programs
Landwehr, J.M.; Tasker, Gary D.
1999-01-01
This report presents a benchmark analysis of several statistical analysis programs currently in use in the USGS. The benchmark consists of a comparison between the values provided by a statistical analysis program for variables in the reference data set ANASTY and their known or calculated theoretical values. The ANASTY data set is an amendment of the Wilkinson NASTY data set that has been used in the statistical literature to assess the reliability (computational correctness) of calculated analytical results.
Hinder, Ian; Boyle, Michael; Etienne, Zachariah B; Healy, James; Johnson-McDaniel, Nathan K; Nagar, Alessandro; Nakano, Hiroyuki; Pan, Yi; Pfeiffer, Harald P; Pürrer, Michael; Reisswig, Christian; Scheel, Mark A; Sperhake, Ulrich; Szilágyi, Bela; Tichy, Wolfgang; Wardell, Barry; Zenginoglu, Anıl; Alic, Daniela; Bernuzzi, Sebastiano; Bode, Tanja; Brügmann, Bernd; Buchman, Luisa T; Campanelli, Manuela; Chu, Tony; Damour, Thibault; Grigsby, Jason D; Hannam, Mark; Haas, Roland; Hemberger, Daniel A; Husa, Sascha; Kidder, Lawrence E; Laguna, Pablo; London, Lionel; Lovelace, Geoffrey; Lousto, Carlos O; Marronetti, Pedro; Matzner, Richard A; Mösta, Philipp; Mroué, Abdul; Müller, Doreen; Mundim, Bruno C; Nerozzi, Andrea; Paschalidis, Vasileios; Pollney, Denis; Reifenberger, George; Rezzolla, Luciano; Shapiro, Stuart L; Shoemaker, Deirdre; Taracchini, Andrea; Taylor, Nicholas W; Teukolsky, Saul A; Thierfelder, Marcus; Witek, Helvi; Zlochower, Yosef
2014-01-01
The Numerical-Relativity-Analytical-Relativity (NRAR) collaboration is a joint effort between members of the numerical relativity, analytical relativity and gravitational-wave data analysis communities. The goal of the NRAR collaboration is to produce numerical-relativity simulations of compact binaries and use them to develop accurate analytical templates for the LIGO/Virgo Collaboration to use in detecting gravitational-wave signals and extracting astrophysical information from them. We describe the results of the first stage of the NRAR project, which focused on producing an initial set of numerical waveforms from binary black holes with moderate mass ratios and spins, as well as one non-spinning binary configuration which has a mass ratio of 10. All of the numerical waveforms are analysed in a uniform and consistent manner, with numerical errors evaluated using an analysis code created by members of the NRAR collaboration. We compare previously-calibrated, non-precessing analytical waveforms, notably the ...
Numerical analysis of wet separation of particles by density differences
Markauskas, Darius
2016-01-01
Wet particle separation is widely used in mineral processing and plastic recycling to separate mixtures of particulate materials into further usable fractions due to density differences. This work presents efforts aiming to numerically analyze the wet separation of particles with different densities. In the current study the discrete element method (DEM) is used for the solid phase while the smoothed particle hydrodynamics (SPH) is used for modeling of the liquid phase. The two phases are coupled by the use of a volume averaging technique. In the current study, simulations of spherical particle separation were performed. In these simulations, a set of generated particles with two different densities is dropped into a rectangular container filled with liquid. The results of simulations with two different mixtures of particles demonstrated how separation depends on the densities of particles.
Numerical analysis of poly-TFTs under off conditions
Colalongo, L.; Valdinoci, M.; Baccarani, G.; Migliorato, P.; Tallarida, G.; Reita, C.
1997-04-01
Polycrystalline silicon thin-film transistors (poly-TFTs) are getting increasingly important for applications in active-matrix flat-panel displays (AMFPDs) and, more generally, for large-area electronics. As the leakage current requirements of poly-TFTs for large area applications become more stringent, it is important to improve our understanding of the physical effects which originate it. The purpose of this work is that of investigating the anomalous behaviour of leakage-currents in poly-TFTs by numerical simulation, taking into account the effect of energy-distributed traps and field-enhanced generation mechanisms. In what follows, we show that the off current is due to the concomitant effects of Poole-Frenkel, trap-assisted and band-to-band tunneling generation mechanisms, and that each of them may be important at different temperature and bias conditions.
Mathematical analysis and numerical methods for science and technology
Dautray, Robert
These 6 volumes - the result of a 10 year collaboration between the authors, two of France's leading scientists and both distinguished international figures - compile the mathematical knowledge required by researchers in mechanics, physics, engineering, chemistry and other branches of application of mathematics for the theoretical and numerical resolution of physical models on computers. Since the publication in 1924 of the "Methoden der mathematischen Physik" by Courant and Hilbert, there has been no other comprehensive and up-to-date publication presenting the mathematical tools needed in applications of mathematics in directly implementable form. The advent of large computers has in the meantime revolutionised methods of computation and made this gap in the literature intolerable: the objective of the present work is to fill just this gap. Many phenomena in physical mathematics may be modeled by a system of partial differential equations in distributed systems: a model here means a set of equations, which ...
Numerical analysis of Coleman-de Luccia tunneling
Goto, Yuhei; Okuyama, Kazumi
2016-08-01
In this paper, we study the false vacuum decay of a single scalar field ϕ coupled to gravity described by the Coleman-de Luccia (CdL) instanton. We show that it is possible to numerically calculate the bounce factor, which is related to the CdL tunneling rate, without using the thin-wall approximation. In this paper, we consider 1/cosh(ϕ)- and cos(ϕ)-type potentials as examples, which have cosmological and phenomenological applications. Especially, in the cos(ϕ)-type potential, we show that the range of values in which axion decay constant can take is restricted by the form of the periodic potential if the CdL tunneling occurs.
Mathematical analysis and numerical simulation of a model of morphogenesis.
Muñoz, Ana I; Tello, José Ignacio
2011-10-01
We consider a simple mathematical model of distribution of morphogens (signaling molecules responsible for the differentiation of cells and the creation of tissue patterns). The mathematical model is a particular case of the model proposed by Lander, Nie and Wan in 2006 and similar to the model presented in Lander, Nie, Vargas and Wan 2005. The model consists of a system of three equations: a PDE of parabolic type with dynamical boundary conditions modelling the distribution of free morphogens and two ODEs describing the evolution of bound and free receptors. Three biological processes are taken into account: diffusion, degradation and reversible binding. We study the stationary solutions and the evolution problem. Numerical simulations show the behavior of the solution depending on the values of the parameters.
Numerical Analysis of Mixed Convection through an Internally Finned Tube
Sachindra Kumar Rout
2012-01-01
Full Text Available Wall temperature of an internally finned tube has been computed numerically for different fin number, height, and shape by solving conservation equations of mass, momentum, and energy using Fluent 12.1 for a steady and laminar flow of fluid inside a tube under mixed flow condition. It has been found that there exists an optimum number for fins to keep the pipe wall temperature at a minimum. The fin height has an optimum value beyond which the wall temperature becomes insensitive to fin height. For a horizontal tube, under mixed flow condition, it is seen that the upper surface has higher average temperature than the lower surface. The impact of fin shape on the heat transfer rate shows that wall temperature is least for triangular-shaped fins, compared to rectangular- and T-shaped fins. In addition to the thermal characteristics, the pressure drop caused due to the presence of fins has also been studied.
Numerical Analysis for Dynamic Instability of Electrodynamic Maglev Systems
Y. Cai
1995-01-01
Full Text Available Suspension instabilities in an electrodynamic maglev system with three- and five-degrees-of-freedom DOF vehicles traveling on a double L-shaped set of guideway conductors were investigated with various experimentally measured magnetic force data incorporated into theoretical models. Divergence and flutter were obtained from both analytical and numerical solutions for coupled vibration of the three-DOF maglev vehicle model. Instabilities of five direction motion (heave, slip, roll, pitch, and yaw were observed for the five-DOF vehicle model. The results demonstrate that system parameters such as system damping, vehicle geometry, and coupling effects among five different motions play very important roles in the occurrence of dynamic instabilities of maglev vehicles.
Numerical Analysis of Coleman-de Luccia Tunneling
Goto, Yuhei
2016-01-01
We study the false vacuum decay of a single scalar field $\\phi$ coupled to gravity described by the Coleman-de Luccia (CdL) instanton. We show that it is possible to numerically calculate the bounce factor, which is related to the CdL tunneling rate, without using the thin-wall approximation. In this paper, we consider $1/\\cosh(\\phi)$- and $\\cos(\\phi)$-type potential as examples, which have cosmological and phenomenological applications. Especially, in the $\\cos(\\phi)$-type potential we show that the range of values in which axion decay constant can take is restricted by the form of the periodic potential if the CdL tunneling occurs.
Computational Notes on the Numerical Analysis of Galactic Rotation Curves
Scelza, G
2014-01-01
In this paper we present a brief discussion on the salient points of the computational analysis that are at the basis of the paper \\cite{StSc}. The computational and data analysis have been made with the software Mathematica$^\\circledR$ and presented at Mathematica Italia User Group Meeting 2011.
Coarse-grained numerical bifurcation analysis of lattice Boltzmann models
Leemput, P. Van; Lust, K.W.A.; Kevrekidis, I.G.
2005-01-01
In this paper we study the coarse-grained bifurcation analysis approach proposed by I.G. Kevrekidis and collaborators in PNAS [C. Theodoropoulos, Y.H. Qian, I.G. Kevrekidis, "Coarse" stability and bifurcation analysis using time-steppers: a reaction-diffusion example, Proc. Natl. Acad. Sci. 97 (18)
Numerical Analysis on Neutron Shielding Structure of ITER Vacuum Vessel
LIU Changle; WU Songtao; YU Jie; SHENG Daolin
2008-01-01
The neutron shielding component of ITER (International Thermonuclear Experi-mental Reactor) vacuum vessel is a kind of structure resembling a wall in appearance. A FE (finite element) model is set up by using ANSYS code in terms of its structural features. Static analysis, thermal expansion analysis and dynamic analysis are performed. The static results show that the stress and displacement distribution are allowable, but the high stress appears in the junction between the upper and lower parts. The modal analysis indicates that the biggest defor-mation exists in the port area. Through modal superposition, the single-point response has been found with the lower rank frequency of the acceleration seismic response spectrum. But the defor-mation and the stress values are within the permissible limit. The analysis results would benefit the work in the next step and provide some reference for the implementation of the engineering plan in the future.
Han, Samuel S.; Schafer, Charles F.
1988-01-01
A numerical analysis of transient heat and solute transport across a rectangular cavity with combined horizontal temperature and concentration gradients is performed by a numerical method based on the SIMPLE. Numerical results show that the average Nusselt and Sherwood numbers both decrease markedly when the solutal and thermal buoyancy forces act in the opposite directions. When the solutal and thermal buoyancy forces act in the same directions, however, the average Sherwood number increases significantly and yet the average Nusselt number decreases slightly.
Wenhua Liang
Full Text Available BACKGROUND: Several EGFR-tyrosine kinase inhibitors (EGFR-TKIs including erlotinib, gefitinib, afatinib and icotinib are currently available as treatment for patients with advanced non-small-cell lung cancer (NSCLC who harbor EGFR mutations. However, no head to head trials between these TKIs in mutated populations have been reported, which provides room for indirect and integrated comparisons. METHODS: We searched electronic databases for eligible literatures. Pooled data on objective response rate (ORR, progression free survival (PFS, overall survival (OS were calculated. Appropriate networks for different outcomes were established to incorporate all evidences. Multiple-treatments comparisons (MTCs based on Bayesian network integrated the efficacy and specific toxicities of all included treatments. RESULTS: Twelve phase III RCTs that investigated EGFR-TKIs involving 1821 participants with EGFR mutation were included. For mutant patients, the weighted pooled ORR and 1-year PFS of EGFR-TKIs were significant superior to that of standard chemotherapy (ORR: 66.6% vs. 30.9%, OR 5.46, 95%CI 3.59 to 8.30, P<0.00001; 1-year PFS: 42.9% vs. 9.7%, OR 7.83, 95%CI 4.50 to 13.61; P<0.00001 through direct meta-analysis. In the network meta-analyses, no statistically significant differences in efficacy were found between these four TKIs with respect to all outcome measures. Trend analyses of rank probabilities revealed that the cumulative probabilities of being the most efficacious treatments were (ORR, 1-year PFS, 1-year OS, 2-year OS: erlotinib (51%, 38%, 14%, 19%, gefitinib (1%, 6%, 5%, 16%, afatinib (29%, 27%, 30%, 27% and icotinib (19%, 29%, NA, NA, respectively. However, afatinib and erlotinib showed significant severer rash and diarrhea compared with gefitinib and icotinib. CONCLUSIONS: The current study indicated that erlotinib, gefitinib, afatinib and icotinib shared equivalent efficacy but presented different efficacy-toxicity pattern for EGFR
无
2007-01-01
Numerical analysis and simulation have been an effective means to develop the advanced growth technology and to control the defects type, size and density for silicon crystals of 300 mm and beyond In the present paper, numerical analysis of the melt flow in the Czochralski (CZ) crystal growth configuration, the three dimensional (3D) modeling, the simulation of melt flow under the magnetic field, the inverse modeling and the time-dependent simulation are reviewed. Finally, comparison of numerical analysis with experimental measurements is discussed.
Molenaar, R.; Van der Tak, C.; Hulskotte, J. [DCMR Milieudienst Rijnmond, Rotterdam (Netherlands)
2009-10-15
Until recently there was much uncertainty about emissions from maritime transport; especially wit respect to the location of the emissions but also partly with regard to volume. By determining the emission of each individual sea-going vessel on its way through the harbor, the total emission of the sector in the Rijnmond harbor area has become much clearer. Key to this approach are the transponder signals frequently sent out by each ship to provide information on location, identity and speed. This new approach turned out to lead to large spatial differences compared to the old generic method in which the total emissions per harbor basin were estimated. [Dutch] Tot voor kort waren de emissies van de zeevaart hoogst onzeker, vooral de locatie van de emissies maar deels ook de omvang. Door van elk individueel zeeschip, op zijn tocht door de haven, de emissie te bepalen is de totale emissie van de sector in het Rijnmondgebied nu veel beter bekend. De sleutel in deze aanpak vormen de transpondersignalen waarmee elk schip zijn plaats, identiteit en snelheid met grote frequentie meldt. De nieuwe methode bleek ruimtelijke grote veranderingen op te leveren ten opzichte van de oude generieke methode waarbij de totale emissies per havenbekken geschat werden.
Igor V. Yurin
2016-09-01
Full Text Available In this article is described the attack on the Italian naval base Taranto, carried out exclusively by the forces of English carrier-based aircraft 11 of November 1940 of year, – the first in the history of war shooting at sea the case of applying the aircraft carriers for inflicting of impacts on the sea bases and the based in them warships. This operation laid way to numerous alliterations in the course World War II. Strategic situation in Mediterranean theater of military actions changed radically after this impact.
Solving American Option Pricing Models by the Front Fixing Method: Numerical Analysis and Computing
R. Company
2014-01-01
analysis of the method is provided. The method preserves positivity and monotonicity of the numerical solution. Consistency and stability properties of the scheme are studied. Explicit calculations avoid iterative algorithms for solving nonlinear systems. Theoretical results are confirmed by numerical experiments. Comparison with other approaches shows that the proposed method is accurate and competitive.
Methods of numerical analysis of 1-dimensional 2-body problem in Wheeler-Feynman electrodynamics
Klimenko, S. V.; Nikitin, I. N.; Urazmetov, W. F.
2000-04-01
Numerical methods for solution of differential equations with deviating arguments describing 1-dimensional ultra-relativistic scattering of 2 identical charged particles in classical electrodynamics with half-retarded/halfadvanced interaction (Wheeler and Feynman, 1949) are developed. A bifurcation of solutions and violation of their reflectional symmetries in the region of velocities v>0.937c are found in numerical analysis.
Numerical stability for velocity-based 2-phase formulation for geotechnical dynamic analysis
Mieremet, M.M.J.
2015-01-01
As a master student in AppliedMathematics at the Delft University of Technology I am highly educated in Numerical Analysis. My interest in this field even mademe choose elective courses such as Advanced Numerical Methods, Applied Finite Elements and Computational Fluid Dynamics. In my search for a c
Numerical simulation and analysis of water flow over stepped spillways
QIAN ZhongDong; HU XiaoQing; HUAI WenXin; AMADOR António
2009-01-01
Numerical simulation of water flow over the stepped spillway is conducted using Mixture multiphase flow model. Different turbulence models are chosen to enclose the controlling equations. The turbulence models investigated are realizable k-ε model, SST k-ω model, v2-f model and LES model. The computational results by the four turbulence models are compared with experimental ones in the following aspects: mean velocity, the spanwise vorticity and the growth of the turbulent boundary layer thickness in the streamwise direction. It is found from the comparison that the realizable k-ε model, in which the rotation tensor is included, shows good performance for simulation of flows involving rotation, boundary layer and recirculation. The realizable k-e model is the most efficient in simulating flow over stepped spillways. Further, the characteristics of water flow on the stepped spillway are studied in terms of the mean velocity profile normal to the pseudo-bottom and the pressure field on the steps based on the simulation results using realizable k-ε model.
Parameter Calibration and Numerical Analysis of Twin Shallow Tunnels
Paternesi, Alessandra; Schweiger, Helmut F.; Scarpelli, Giuseppe
2017-05-01
Prediction of displacements and lining stresses in underground openings represents a challenging task. The main reason is primarily related to the complexity of this ground-structure interaction problem and secondly to the difficulties in obtaining a reliable geotechnical characterisation of the soil or the rock. In any case, especially when class A predictions fail in forecasting the system behaviour, performing class B or C predictions, which rely on a higher level of knowledge of the surrounding ground, can represent a useful resource for identifying and reducing model deficiencies. The case study presented in this paper deals with the construction works of twin-tube shallow tunnels excavated in a stiff and fine-grained deposit. The work initially focuses on the ground parameter calibration against experimental data, which together with the choice of an appropriate constitutive model plays a major role in the assessment of tunnelling-induced deformations. Since two-dimensional analyses imply initial assumptions to take into account the effect of the 3D excavation, three-dimensional finite element analyses were preferred. Comparisons between monitoring data and results of numerical simulations are provided. The available field data include displacements and deformation measurements regarding both the ground and tunnel lining.
Experimental and Numerical Failure Analysis of Adhesive Composite Joints
Farhad Asgari Mehrabadi
2012-01-01
Full Text Available In the first section of this work, a suitable data reduction scheme is developed to measure the adhesive joints strain energy release rate under pure mode-I loading, and in the second section, three types of adhesive hybrid lap-joints, that is, Aluminum-GFRP (Glass Fiber Reinforced Plastic, GFRP-GFRP, and Steel-GFRP were employed in the determination of adhesive hybrid joints strengths and failures that occur at these assemblies under tension loading. To achieve the aims, Double Cantilever Beam (DCB was used to evaluate the fracture state under the mode-I loading (opening mode and also hybrid lap-joint was employed to investigate the failure load and strength of bonded joints. The finite-element study was carried out to understand the stress intensity factors in DCB test to account fracture toughness using J-integral method as a useful tool for predicting crack failures. In the case of hybrid lap-joint tests, a numerical modeling was also performed to determine the adhesive stress distribution and stress concentrations in the side of lap-joint. Results are discussed in terms of their relationship with adhesively bonded joints and thus can be used to develop appropriate approaches aimed at using adhesive bonding and extending the lives of adhesively bonded repairs for aerospace structures.
NUMERICAL ANALYSIS OF NATURAL CONVECTION IN A PRISMATIC ENCLOSURE
Walid AICH
2011-01-01
Full Text Available Natural convection heat transfer and fluid flow have been examined numerically using the control-volume finite-element method in an isosceles prismatic cavity, submitted to a uniform heat flux from below when inclined sides are maintained isothermal and vertical walls are assumed to be perfect thermal insulators, without symmetry assumptions for the flow structure. The aim of the study is to examine a pitchfork bifurcation occurrence. Governing parameters on heat transfer and flow fields are the Rayleigh number and the aspect ratio of the enclosure. It has been found that the heated wall is not isothermal and the flow structure is sensitive to the aspect ratio. It is also found that heat transfer increases with increasing of Rayleigh number and decreases with increasing aspect ratio. The effects of aspect ratio become significant especially for higher values of Rayleigh number. Eventually the obtained results show that a pitchfork bifurcation occurs at a critical Rayleigh number, above which the symmetric solutions becomes unstable and asymmetric solutions are instead obtained.
Numerical Analysis including Pressure Drop in Oscillating Water Column Device
das Neves Gomes, Mateus; Domingues dos Santos, Elizaldo; Isoldi, Liércio André; Rocha, Luiz Alberto Oliveira
2015-06-01
The wave energy conversion into electricity has been increasingly studied in the last years. There are several proposed converters. Among them, the oscillatingwater column (OWC) device has been widespread evaluated in literature. In this context, the main goal of this work was to perform a comparison between two kinds of physical constraints in the chimney of the OWC device, aiming to represent numerically the pressure drop imposed by the turbine on the air flow inside the OWC. To do so, the conservation equations of mass,momentumand one equation for the transport of volumetric fraction were solved with the finite volume method (FVM). To tackle thewater-air interaction, the multiphase model volume of fluid (VOF)was used. Initially, an asymmetric constraint inserted in chimney duct was reproduced and investigated. Subsequently, a second strategywas proposed,where a symmetric physical constraint with an elliptical shapewas analyzed. Itwas thus possible to establish a strategy to reproduce the pressure drop in OWC devices caused by the presence of the turbine, as well as to generate its characteristic curve.
Relating observations of contrail persistence to numerical weather analysis output
D. P. Duda
2008-10-01
Full Text Available The potential for using high-resolution meteorological data from two operational numerical weather analyses (NWA to diagnose and predict persistent contrail formation is evaluated using two independent contrail observation databases. Contrail occurrence statistics derived from surface and satellite observations between April 2004 and June 2005 are matched to the humidity, vertical velocity, wind shear and atmospheric stability derived from analyses from the Rapid Update Cycle (RUC and the Advanced Regional Prediction System (ARPS models. The relationships between contrail occurrence and the NWA-derived statistics are analyzed to determine under which atmospheric conditions persistent contrail formation is favored within NWAs. Humidity is the most important factor determining whether contrails are short-lived or persistent, and persistent contrails are more likely to appear when vertical velocities are positive, and more likely to spread when the atmosphere is less stable. Although artificial upper limits on upper tropospheric humidity within the NWAs prevent a direct quantitative agreement of model data with contrail formation theory, logistic regression or similar statistical methods may improve the prediction of contrail occurrence.
Numerical Bifurcation Analysis of Conformal Formulations of the Einstein Constraints
Holst, M
2011-01-01
The Einstein constraint equations have been the subject of study for more than fifty years. The introduction of the conformal method in the 1970's as a parameterization of initial data for the Einstein equations led to increased interest in the development of a complete solution theory for the constraints, with the theory for constant mean curvature (CMC) spatial slices and closed manifolds completely developed by 1995. The first general non-CMC existence result was establish by Holst et. al in 2008, with extensions to rough data by Holst et. al in 2009, and to vacuum spacetimes by Maxwell in 2009. The non-CMC theory remains mostly open; moreover, recent work of Maxwell on specific symmetry models sheds light on fundamental non-uniqueness problems with the conformal method as a parameterization in non-CMC settings. In parallel with these mathematical developments, computational physicists have uncovered surprising behavior in numerical solutions to the extended conformal thin sandwich formulation of the Einst...
Numerical simulation and analysis of water flow over stepped spillways
AMADOR; António
2009-01-01
Numerical simulation of water flow over the stepped spillway is conducted using Mixture multiphase flow model. Different turbulence models are chosen to enclose the controlling equations. The turbulence models investigated are realizable k-ε model, SST k-ω model, v2-f model and LES model. The computational results by the four turbulence models are compared with experimental ones in the following aspects: mean velocity, the spanwise vorticity and the growth of the turbulent boundary layer thickness in the streamwise direction. It is found from the comparison that the realizable k-ε model, in which the rotation tensor is included, shows good performance for simulation of flows involving rotation, boundary layer and recirculation. The realizable k-ε model is the most efficient in simulating flow over stepped spillways. Further, the characteristics of water flow on the stepped spillway are studied in terms of the mean velocity profile normal to the pseudo-bottom and the pressure field on the steps based on the simulation results using realizable k-ε model.
Numerical analysis of extensional flow through the pharyngeal duct
Preciado-Méndez, M.; Salinas-Vázquez, M.; Vicente, W.; Brito-de la Fuente, E.; Ascanio, G.
2017-01-01
The flow through the pharynx from the glossopalatal junction (GPJ) to the upper esophageal sphincter (UES) has been numerically investigated with a non-Newtonian fluid obeying the power-law with similar rheological indices to a contrast medium used in videofluroscopy. For that purpose, a three-dimensional model of the transport of food bolus along the pharynx has been proposed using the immersed boundaries method, which allow representing the shape of the pharynx using Cartesian grids. The pharyngeal wall has been considered to be an elastic membrane. Flow fields in terms of the axial velocity, pressure, shear rate and strain rate were obtained. Results show that the highest velocity concentrates in the central stream as the fluid enters into the pharynx. In addition, as the flow quits the pharynx, a recirculation zone appears inside the cavity, resulting in low velocity zone, which increases with the coefficient of elasticity. A strong dependence on the coefficient of elasticity was observed on the pressure fields; so that as such a coefficient increases, the pressure in the pharyngeal wall will increase. It has been also observed that the bolus head travels faster than the bolus tail, which indicates that the bolus is not only subjected to shear but also to elongation. Results from this work can be further used for a rheological characterization (shear and extension) of oral nutritional supplements for patients suffering from swallowing disorders.
Mechanical behavior and numerical analysis of corrugated wire mesh laminates
Choi, Jeong Ho; Shankar, Krishna; Tahtali, Murat [UNSW, ADFA, Canberra (Australia)
2012-01-15
The objective is to show a possibility of corrugated wire mesh laminate (CWML) structure for bone application. CWML is a part of open-cell structures with low density and high strength built with bonded mesh layers. Specimens of CWML made of 316 stainless steel woven meshes with 0.22 mm wire diameter and 0.95 mm mesh aperture, bonded by transit liquid phase (TLP) at low temperatures, were fabricated and tested under quasi-static conditions to determine their compressive behavior with varying numbers of layers of the sample. The finite element software was used to model the CWML and studied their response to mechanical loading. Then, the numerical model was confirmed by the tested sample. Consequently, CWML specimens were reasonably matched with the human tibia bone ranged over apparent density from 0.05 to 0.08 g/cm{sup 3} in Young's modulus and from 0.05 to 0.11 g/cm{sup 3} in compressive yield strength. The CWML model can have the potential for bone application.
Numerical Analysis and Centrifuge Modeling of Shallow Foundations
罗强; 栾茂田; 杨蕴明; 王忠涛; 赵守正
2014-01-01
The influence of non-coaxial constitutive model on predictions of dense sand behavior is investigated in this paper. The non-coaxial model with strain softening plasticity is applied into finite-element program ABAQUS, which is first used to predict the stress-strain behavior and the non-coaxial characteristic between the orientations of the principal stress and principal plastic strain rate in simple shear tests. The model is also used to predict load settlement responses and bearing capacity factors of shallow foundations. A series of centrifuge tests for shallow foundations on saturated dense sand are performed under drained conditions and the test results are compared with the corresponding numerical results. Various footing dimensions, depths of embedment, and footing shapes are considered in these tests. In view of the load settlement relationships, the stiffness of the load-displacement curves is significantly affected by the non-coaxial model compared with those predicted by the coaxial model, and a lower value of non-coaxial modulus gives a softer response. Considering the soil behavior at failure, the coaxial model predictions of bearing capacity factors are more advanced than those of centrifuge test results and the non-coaxial model results;besides, the non-coaxial model gives better predictions. The non-coaxial model predictions are closer to those of the centrifuge results when a proper non-coaxial plastic modulus is chosen.
Numerical analysis on letdown system performance test for YGN 3
Seo, Ho Taek; Sohn, Seok Hoon; Seo, Jong Tae [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)
1996-09-01
Integrated performance test of Chemical and Volume control System was successfully performed in 1994. However, an extensive effort to correct hardware and software problems in the letdown line was required mainly due to the lack of adequate simulation code to predict the test accurately. Although the LTC computer code was used during the YGN 3 and 4 NSSS design process, the code can not satisfactorily predict the test due to its insufficient letdown line modeling. This study developed a numerical model to simulate the letdown test by modifying the current LTC code, and then verified the model by comparing with the test data. The comparison shows that the modified LTC computer code can predict the transient behavior of letdown system tests very well. Especially, the model was verified to be able to predict the instantaneous fluctuations in the letdown backpressure and flowrate which are caused by the `Stiction (composition of stick and friction)` of valve. Therefore, it is concluded that the modified LTC computer code with the ability of calculating the `Stiction` phenomena will be very useful for future plant design and test predictions. 1 tab., 11 figs., 7 refs. (Author).
Enzyme polymorphism in Endotrypanum and numerical analysis of isoenzyme data.
Franco, A M; Momen, H; Naiff, R D; Moreira, C F; Deane, M P; Grimaldi Júnior, G
1996-07-01
In this study, we have analysed enzyme polymorphism among a group of protozoan parasites of the genus Endotrypanum (Kinetoplastida: Trypanosomatidae). Seventeen stocks of Endotrypanum spp. isolated from sloths (Choloepus didactylus and C. juruanus) in the Amazon Region of Brazil were analysed by enzyme electrophoresis, and their electromorphic profiles were compared with reference strains reported previously. The 16 enzymic loci were analysed, and the strains were classified into zymodemes, each representing parasites with unique enzyme profiles. Each zymodeme was considered as an elementary taxon, and using numerical analyses (cladistic, agglomerative hierarchical and ordination techniques) the genus was shown to be monophyletic and the 12 zymodemes characterized could be divided into 3 groups (A, B, C). The heterogeneous population (which may represent a complex of parasite species or strains variants) showed, however, no correlation with the origin (i.e. host species involved or geographic area of isolation) of Endotrypanum stocks. Eight isolates of Endotrypanum sp. from Rondônia State (Brazil) and a parasite strain from Panama were clustered together into a zymodeme, which was phenetically closely related to the E. monterogeii from Costa Rica. The data indicate that E. schaudinni is a species complex.
Numerical Analysis of a Radiant Heat Flux Calibration System
Jiang, Shanjuan; Horn, Thomas J.; Dhir, V. K.
1998-01-01
A radiant heat flux gage calibration system exists in the Flight Loads Laboratory at NASA's Dryden Flight Research Center. This calibration system must be well understood if the heat flux gages calibrated in it are to provide useful data during radiant heating ground tests or flight tests of high speed aerospace vehicles. A part of the calibration system characterization process is to develop a numerical model of the flat plate heater element and heat flux gage, which will help identify errors due to convection, heater element erosion, and other factors. A 2-dimensional mathematical model of the gage-plate system has been developed to simulate the combined problem involving convection, radiation and mass loss by chemical reaction. A fourth order finite difference scheme is used to solve the steady state governing equations and determine the temperature distribution in the gage and plate, incident heat flux on the gage face, and flat plate erosion. Initial gage heat flux predictions from the model are found to be within 17% of experimental results.
Army Engineer Divers: First In Port-Au-Prince Harbor
2010-12-01
America . Shortly after the quake hit, United States Southern Command (SOUTHCOM) diverted the USNS Grasp and the 544th to Port-au-Prince. Once there...Prince harbor. Pe- troleum floated on top of the water, and numerous marine hazards like jellyfish , human waste, and debris floated be- neath the
Numerical analysis of rainfall effects in external overburden dump
Radhakanta Koner⇑; Debashish Chakravarty
2016-01-01
The effect of slope angle for external overburden dump in response to average and heavy rainfall has been analyzed using a two dimensional finite difference method of transient water flow through unsaturated–saturated soil. The external dump stability is evaluated for five geomaterial types on the basis of globally accepted safety factor analysis technique, based on shear strength reduction approach using finite differ-ence method. The results obtained from the finite difference method of analysis indicate that the external dump with more than 30? slope angle is greatly influenced by the rainfall under the studied conditions for geomaterial 3, 4 and 5, whereas dumps with geomaterial 1 and 2 remain safe. The analysis shows that major slope failure is out of preview for the studied rainfall conditions.
Numeric Analysis for Relationship-Aware Scalable Streaming Scheme
Heung Ki Lee
2014-01-01
Full Text Available Frequent packet loss of media data is a critical problem that degrades the quality of streaming services over mobile networks. Packet loss invalidates frames containing lost packets and other related frames at the same time. Indirect loss caused by losing packets decreases the quality of streaming. A scalable streaming service can decrease the amount of dropped multimedia resulting from a single packet loss. Content providers typically divide one large media stream into several layers through a scalable streaming service and then provide each scalable layer to the user depending on the mobile network. Also, a scalable streaming service makes it possible to decode partial multimedia data depending on the relationship between frames and layers. Therefore, a scalable streaming service provides a way to decrease the wasted multimedia data when one packet is lost. However, the hierarchical structure between frames and layers of scalable streams determines the service quality of the scalable streaming service. Even if whole packets of layers are transmitted successfully, they cannot be decoded as a result of the absence of reference frames and layers. Therefore, the complicated relationship between frames and layers in a scalable stream increases the volume of abandoned layers. For providing a high-quality scalable streaming service, we choose a proper relationship between scalable layers as well as the amount of transmitted multimedia data depending on the network situation. We prove that a simple scalable scheme outperforms a complicated scheme in an error-prone network. We suggest an adaptive set-top box (AdaptiveSTB to lower the dependency between scalable layers in a scalable stream. Also, we provide a numerical model to obtain the indirect loss of multimedia data and apply it to various multimedia streams. Our AdaptiveSTB enhances the quality of a scalable streaming service by removing indirect loss.
Modern Numerical Methods for Classical Sampled System Analysis-SAMSAN
Frisch, H. P.
1984-01-01
SAMSAN aids control-system analyst by providing self-consistent set of computer algorithms that support large-order control-system design and evaluation studies, with emphasis placed on sampled system analysis. Program provides set of algorithms readily integrated for solving control-system problems.
Numerical Methods for Classical Sampled-System Analysis
Frisch, H. P.; Bauer, F. H.
1986-01-01
SAMSAN provides control-system analyst with self-consistent computer algorithms that support large-order control-system design and evaluation studies. Emphasizes sampled-system analysis. SAMSAN reduces burden on analyst by providing set of algorithms well tested and documented and readily integrated for solving control-system problems.
Numerical Fracture Analysis of Cryogenically Treated Alloy Steel Weldments
Rasool Mohideen, S.; Thamizhmanii, S.; Fatah, M. M. Muhammed Abdul; Saidin, W. Najmuddin W.
2016-02-01
Cryogenic treatment is being used commercially in the industries in the last two decades for improving the life of many engineering component such as bearings and cutting tools. Though their influence in improving the wear resistance of tool materials is well established, the effect of treatment on weldments is not much investigated. In the present work, a two dimensional finite element analysis was carried out on the compact tension specimen model for simulating the treatment process and to study the fracture behaviour. The weldments were modelled by thermo- mechanical coupled field analysis for simulating he temperature distribution in the model during weld pool cooling and introducing thermal stresses due to uneven contraction and cooling. The model was subjected to cryogenic treatment by adopting radiation effect. The fracture analysis was carried out using Rice's J- Integral approach. The analysis produced a similar outcome of experimental results i.e. Increase in the fracture toughness of the specimen after cryogenic treatment in the heat affected zone of weldment.
Numerical limit analysis of keyed shear joints in concrete structures
Herfelt, Morten Andersen; Poulsen, Peter Noe; Hoang, Linh Cao
2016-01-01
of the authors, previous theoretical works and present design equations in standards do not account for this important effect. In this paper, a detailed model based on finite element limit analysis is introduced to assess the effect of the discontinuous reinforcement. The model is based on the lower bound...
Urban, F.K., E-mail: urban@fiu.edu; Barton, D.
2015-05-29
Useful thin film information may be obtained using ellipsometry data recorded during film growth. In cases in which the growing film overlies a substrate already coated with other films, it is possible to use a model which includes prior knowledge of the optical properties and layer thicknesses of all underlying films and the substrate. However, accuracy of the analysis is limited by imprecision in knowledge of the underlying structure and is not possible if the underlying material structure is unknown. These problems may be addressed by substituting a four-variable “numerical substrate” in place of the underlying materials. The “numerical substrate” exactly mathematically replaces a model of the physical substrate. It is represented by two effective optical indices which are independent of the growing film and dependent only upon light incidence angle and wavelength. The method may be implemented with a set of five measurements at a single wavelength and incidence angle or a set of three measurements at each of two incidence angles. Measurements may be made in-situ during film growth or ex-situ using “step deposited” films of different thicknesses. The work presented here is to demonstrate the method for nickel and rhenium films deposited on a BK7 substrate by Yamamoto using ion sputtering. - Highlights: • Ellipsometry data were taken in-situ. • Data are single angle, single wavelength. • Film nucleation layers are strongly vertically inhomogeneous. • Upper layers were nearly homogeneous. • Solutions used five measurements at different times.
V. A. Golovin
1986-04-01
Full Text Available The algorithms of numerical and symbolic analysis methods of linear chains of derivatives and LU-decomposition. An example of the calculation circuit functions using programs that implement the proposed algorithms.
Numerical analysis of the non-contacting gas face seals
Blasiak, S.
2017-08-01
The non-contacting gas face seals are used in high-performance devices where the main requirements are safety and reliability. Compliance with these requirements is made possible by careful research and analysis of physical processes related to, inter alia, fluid flow through the radial gap and ring oscillations susceptible to being housed in the enclosure under the influence of rotor kinematic forces. Elaborating and developing mathematical models describing these phenomena allows for more and more accurate analysis results. The paper presents results of studies on stationary ring oscillations made of different types of materials. The presented results of the research allow to determine which of the materials used causes the greatest amplitude of the vibration of the system fluid film-working rings.
Numerical Analysis of a Blocking Mass Attenuating Wave Propagation
Xianzhong Wang; Xiongliang Yao; Qiangyong Wang; Shuai Lv
2011-01-01
Based on wave theory,blocking mass impeding propagation of flexural waves was analyzed with force excitation applied on a ship pedestal.The analysis model of a complex structure was developed by combining statistical energy analysis and the finite element method.Based on the hybrid FE-SEA method,the vibro-acoustic response of a complex structure was solved.Then,the sound radiation of a cylindrical shell model influenced by blocking mass was calculated in mid/high frequency.The result shows that blocking mass has an obvious effect on impeding propagation.The study provides a theoretical and experimental basis for application of the blocking mass to structure-borne sound propagation control.
A Numerical Model for Torsion Analysis of Composite Ship Hulls
Ionel Chirica
2012-01-01
Full Text Available A new methodology based on a macroelement model proposed for torsional behaviour of the ship hull made of composite material is proposed in this paper. A computer program has been developed for the elastic analysis of linear torsion. The results are compared with the FEM-based licensed soft COSMOS/M results and measurements on the scale simplified model of a container ship, made of composite materials.
Stadelmann, Vincent A; Hocke, Jean; Verhelle, Jensen; Forster, Vincent; Merlini, Francesco; Terrier, Alexandre; Pioletti, Dominique P
2009-02-01
A combined experimental/numerical study was performed to calculate the 3D octahedral shear strain map in a mouse tibia loaded axially. This study is motivated by the fact that the bone remodelling analysis, in this in vivo mouse model should be performed at the zone of highest mechanical stimulus to maximise the measured effects. Accordingly, it is proposed that quantification of bone remodelling should be performed at the tibial crest and at the distal diaphysis. The numerical model could also be used to furnish a more subtle analysis as a precise correlation between local strain and local biological response can be obtained with the experimentally validated numerical model.
Application of nonlinear optimization method to sensitivity analysis of numerical model
XU Hui; MU Mu; LUO Dehai
2004-01-01
A nonlinear optimization method is applied to sensitivity analysis of a numerical model. Theoretical analysis and numerical experiments indicate that this method can give not only a quantitative assessment whether the numerical model is able to simulate the observations or not, but also the initial field that yields the optimal simulation. In particular, when the simulation results are apparently satisfactory, and sometimes both model error and initial error are considerably large, the nonlinear optimization method, under some conditions, can identify the error that plays a dominant role.
Ignat'ev, Yu G
2016-01-01
In this paper we investigate the asymptotic behavior of the cosmological model based on phantom scalar field on the ground of qualitative analysis of the system of the cosmological model's differential equations and show that as opposed to models with classical scalar field, such models have stable asymptotic solutions with constant value of the potential both in infinite past and infinite future. We also develop numerical models of the cosmological evolution models with phantom scalar field in this paper. {\\bf keywords}: cosmological model, phantom scalar field, quality analysis, asymptotic behavior, numerical simulation, numerical gravitation.\\\\ {\\bf PACS}: 04.20.Cv, 98.80.Cq, 96.50.S 52.27.Ny
Quantitative numerical analysis of transient IR-experiments on buildings
Maierhofer, Ch.; Wiggenhauser, H.; Brink, A.; Röllig, M.
2004-12-01
Impulse-thermography has been established as a fast and reliable tool in many areas of non-destructive testing. In recent years several investigations have been done to apply active thermography to civil engineering. For quantitative investigations in this area of application, finite difference calculations have been performed for systematic studies on the influence of environmental conditions, heating power and time, defect depth and size and thermal properties of the bulk material (concrete). The comparison of simulated and experimental data enables the quantitative analysis of defects.
Reliability Distribution of Numerical Control Lathe Based on Correlation Analysis
Xiaoyan Qi; Guixiang Shen; Yingzhi Zhang; Shuguang Sun; Bingkun Chen
2016-01-01
Combined Reliability distribution with correlation analysis, a new method has been proposed to make Reliability distribution where considering the elements about structure correlation and failure correlation of subsystems. Firstly, we make a sequence for subsystems by means of TOPSIS which comprehends the considerations of Reliability allocation, and introducing a Copula connecting function to set up a distribution model based on structure correlation, failure correlation and target correlation, and then acquiring reliability target area of all subsystems by Matlab. In this method, not only the traditional distribution considerations are concerned, but also correlation influences are involved, to achieve supplementing information and optimizing distribution.
The numerical thermodynamic analysis of Otto-Miller Cycle (OMC
Cakir Mehmet
2016-01-01
Full Text Available This paper presents a thermodynamic analysis for an irreversible Otto-Miller Cycle (OMC by taking into consideration heat transfer effects and internal irreversibilities resulting from compression and expansion processes. In the analyses, the influences of the miller cycle ratio, combustion and heat loss constants and inlet temperature have been investigated relations with efficiency in dimensionless form. The dimensionless power output and power density and thermal efficiency relations have been computationally obtained versus the engine design parameters with respect to combustion and heat transfer constants. The results demonstrate that the heat transfer and combustion constants have considerable effects on the cycle thermodynamic performance. This situation theoretically verified for OMC.
Numerical analysis of helium-heated methane/steam reformer
Mozdzierz, M.; Brus, G.; Kimijima, S.; Szmyd, J. S.
2016-09-01
One of the most promising between many high temperature nuclear reactors applications is to produce hydrogen with heat gained. The simplest and the best examined method is steam reforming of methane. The fabricated hydrogen has wide range of use, for example can be electrochemically oxidized in fuel cells. However, heat management inside methane/steam reformer is extremely important because huge temperature gradients can cause catalyst deactivation. In this work the analysis of temperature field inside helium-heated methane/steam reformer is presented. The optimal system working conditions with respect to methane conversion rate are proposed.
NUMERICAL ANALYSIS ON BINOMIAL TREE METHODS FOR AMERICAN LOOKBACK OPTIONS
戴民
2001-01-01
Lookback options are path-dependent options. In general, the binomial tree methods,as the most popular approaches to pricing options, involve a path dependent variable as well as the underlying asset price for lookback options. However, for floating strike lookback options, a single-state variable binomial tree method can be constructed. This paper is devoted to the convergence analysis of the single-state binomial tree methods both for discretely and continuously monitored American floating strike lookback options. We also investigate some properties of such options, including effects of expiration date, interest rate and dividend yield on options prices,properties of optimal exercise boundaries and so on.
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.
Numerical analysis of surface subsidence in asymmetric parallel highway tunnels
Ratan Das
2017-02-01
Full Text Available Tunnelling related hazards are very common in the Himalayan terrain and a number of such instances have been reported. Several twin tunnels are being planned for transportation purposes which will require good understanding for prediction of tunnel deformation and surface settlement during the engineering life of the structure. The deformational behaviour, design of sequential excavation and support of any jointed rock mass are challenging during underground construction. We have raised several commonly assumed issues while performing stability analysis of underground opening at shallow depth. For this purpose, Kainchi-mod Nerchowck twin tunnels (Himachal Pradesh, India are taken for in-depth analysis of the stability of two asymmetric tunnels to address the influence of topography, twin tunnel dimension and geometry. The host rock encountered during excavation is composed mainly of moderately to highly jointed grey sandstone, maroon sandstone and siltstones. In contrast to equidimensional tunnels where the maximum subsidence is observed vertically above the centreline of the tunnel, the result from the present study shows shifting of the maximum subsidence away from the tunnel centreline. The maximum subsidence of 0.99 mm is observed at 4.54 m left to the escape tunnel centreline whereas the maximum subsidence of 3.14 mm is observed at 8.89 m right to the main tunnel centreline. This shifting clearly indicates the influence of undulating topography and in-equidimensional noncircular tunnel.
Numerical Flow Analysis of a Hydraulic Gear Pump
Panta, Yogendra M.; Kim, Hyun W.; Pierson, Hazel M.
2007-11-01
The pressure that exists at the outlet port of a gear pump is a result of system load that was created by a resistance to the fluid flow. However, the flow pattern created inside an external gear pump by the motion of two oppositely rotating gears is deceptively complex, despite the simple geometry of the gear pump. The flow cannot be analyzed, based on a steady-state assumption that is usually employed to analyze turbo-machinery although the flow is essentially steady. Only the time-dependent, transient analysis with moving dynamic meshing technique can predict the motion of the fluid flow against the very high adverse pressure distribution. Although the complexity of analysis is inherent in all positive displacement pumps, gear pumps pose an exceptional challenge in modeling due to the fact that there are two rotating components that are housed within a stationary casing and the gears must be in contact with each other all the time. Fluent, commercially available computational fluid dynamics (CFD) software was used to analyze the flow of the gear pump. The investigation done by CFD produced significant information on flow patterns, velocity and pressure fields, and flow rates.
Structural Analysis of Composite Laminates using Analytical and Numerical Techniques
Sanghi Divya
2016-01-01
Full Text Available A laminated composite material consists of different layers of matrix and fibres. Its properties can vary a lot with each layer’s or ply’s orientation, material property and the number of layers itself. The present paper focuses on a novel approach of incorporating an analytical method to arrive at a preliminary ply layup order of a composite laminate, which acts as a feeder data for the further detailed analysis done on FEA tools. The equations used in our MATLAB are based on analytical study code and supply results that are remarkably close to the final optimized layup found through extensive FEA analysis with a high probabilistic degree. This reduces significant computing time and saves considerable FEA processing to obtain efficient results quickly. The result output by our method also provides the user with the conditions that predicts the successive failure sequence of the composite plies, a result option which is not even available in popular FEM tools. The predicted results are further verified by testing the laminates in the laboratory and the results are found in good agreement.
Sensitivity analysis of numerical model of prestressed concrete containment
Bílý, Petr, E-mail: petr.bily@fsv.cvut.cz; Kohoutková, Alena, E-mail: akohout@fsv.cvut.cz
2015-12-15
Graphical abstract: - Highlights: • FEM model of prestressed concrete containment with steel liner was created. • Sensitivity analysis of changes in geometry and loads was conducted. • Steel liner and temperature effects are the most important factors. • Creep and shrinkage parameters are essential for the long time analysis. • Prestressing schedule is a key factor in the early stages. - Abstract: Safety is always the main consideration in the design of containment of nuclear power plant. However, efficiency of the design process should be also taken into consideration. Despite the advances in computational abilities in recent years, simplified analyses may be found useful for preliminary scoping or trade studies. In the paper, a study on sensitivity of finite element model of prestressed concrete containment to changes in geometry, loads and other factors is presented. Importance of steel liner, reinforcement, prestressing process, temperature changes, nonlinearity of materials as well as density of finite elements mesh is assessed in the main stages of life cycle of the containment. Although the modeling adjustments have not produced any significant changes in computation time, it was found that in some cases simplified modeling process can lead to significant reduction of work time without degradation of the results.
COMBUSTION STAGE NUMERICAL ANALYSIS OF A MARINE ENGINE
DOREL DUMITRU VELCEA
2016-06-01
Full Text Available The primary goal of engine design is to maximize each efficiency factor, in order to extract the most power from the least amount of fuel. In terms of fluid dynamics, the volumetric and combustion efficiency are dependent on the fluid dynamics in the engine manifolds and cylinders. Cold flow analysis involves modeling the airflow in the transient engine cycle without reactions. The goal is to capture the mixture formation process by accurately accounting for the interaction of moving geometry with the fluid dynamics of the induction process. The changing characteristics of the air flow jet that tumbles into the cylinder with swirl via intake valves and the exhaust jet through the exhaust valves as they open and close can be determined, along with the turbulence production from swirl and tumble due to compression and squish. The target of this paper was to show how, by using the reverse engineering techniques, one may replicate and simulate the functioning conditions and parameters of an existing marine engine. The departing information were rather scarce in terms of real processes taking place in the combustion stage, but at the end we managed to have a full picture of the main parameters evolution during the combustion phase inside this existing marine engine
Numerical Analysis of Microwave Heating on Saponification Reaction
Huang, Kama; Jia, Kun
2005-01-01
Currently, microwave is widely used in chemical industry to accelerate chemical reactions. Saponification reaction has important applications in industry; some research results have shown that microwave heating can significantly accelerate the reaction [1]. But so far, no efficient method has been reported for the analysis of the heating process and design of an efficient reactor powered by microwave. In this paper, we present a method to study the microwave heating process on saponification reaction, where the reactant in a test tube is considered as a mixture of dilute solution. According to the preliminary measurement results, the effective permittivity of the mixture is approximately the permittivity of water, but the conductivity, which could change with the reaction, is derived from the reaction equation (RE). The electromagnetic field equation and reaction equation are coupled by the conductivity. Following that, the whole heating processes, which is described by Maxwell's equations, the reaction equation and heat transport equation (HTE), is analyzed by finite difference time domain (FDTD) method. The temperature rising in the test tube are measured and compared with the computational results. Good agreement can be seen between the measured and calculated results.
Separate direct injection of diesel and ethanol: A numerical analysis
Burnete Nicolae V.
2017-01-01
Full Text Available The purpose of this study is to investigate the theoretical possibility of using a pilot diesel injection for the auto-ignition of a main ethanol injection in a compression ignition engine. To this effect a predictive simulation model has been built based on experimental results for a diesel cycle (pilot and main injection at 1500 and 2500 min–1, respectively. For every engine speed, in addition to the diesel reference cycle, two more simulations were done: one with the same amount of fuel injected into the cylinder and one with the same amount of energy, which required an increase in the quantity of ethanol proportional to the ratio of its lower heating value and that of diesel. The simulations showed that in all cases the pilot diesel led to the auto-ignition of ethanol. The analysis of the in-cylinder traces at 1500 min–1 showed that combustion efficiency is improved, the peak temperature value decrease with approximately 240 K and, as a result, the NO emissions are 3.5-4 times lower. The CO and CO2 values depend on the amount of fuel injected into the cylinder. At 2500 min–1 there are similar trends but with the following observations: the ignition delay increases, while the pressure and temperature are lower.
Experimental and numerical analysis of automotive gearbox rattle noise
Kadmiri, Younes; Rigaud, Emmanuel; Perret-Liaudet, Joël; Vary, Laurence
2012-06-01
The aim of this work is to characterize the rattle noise of automotive gearboxes, resulting from impacts between toothed wheels of unselected gear ratios. These stereo-mechanical impacts are modeled by a coefficient of restitution which describes damping during the squeezing of the lubricant film for approaching surfaces, and the elastic deformation of impacting bodies. The dynamic response of the loose gear first depends on the design parameters and the engine operating conditions. The unknown parameters are the drag torque and the coefficient of restitution. They are identified experimentally through implementation of two optical encoders in an actual automotive gearbox and the operation of a specific test bench which replicates the automotive power train. Models of the different drag torque sources are validated from analysis of the free damped response of the driveline. The coefficient of restitution and its probability density function are measured from experiments under stationary operating conditions. A nonlinear model is built. The dynamic response of the loose gear depends on the dimensionless backlash, the coefficient of restitution and a dimensionless parameter proposed to describe the rattle excitation level. Experiments under controlled excitation are performed to validate the assumptions, to confirm the ability of the parameter proposed to describe the rattle noise threshold, and to characterize the dynamic response. The nonlinear model predictions are fitted with the drag torque and coefficient of restitution previously identified. They are compared with measurements to demonstrate the ability of the model to predict gear rattle for any loose gear, any gearbox and any operating condition.
Efficient planning and numerical analysis of industrial hemming processes
Burchitz, Igor; Fritsche, David; Grundmann, Göran; Hillmann, Matthias
2011-08-01
Hemming is a forming operation used in the automotive industry to join inner and outer components during the assembly of closures. These are typically opening parts of the body-in-white with additional requirements to their visual appearance. A suitable production concept of hemming operation which satisfies quality, capacity and cost requirements is determined during hemming planning activities. A digital tool to facilitate these activities and minimize the amount of trial and error iterations in try-out phase is presented in this paper. This tool can be used to define process plan, active tool surfaces and suitable process parameters for both die hemming and roll hemming operations. In case of early feasibility studies, when the die layout of the drawing operation is still not available, 3D part geometry is used directly to develop the concept of hemming process. Advanced validation studies, aimed at process optimization and controlling defects associated with hemming, can be based on complete simulation of all forming operations. Validation and analysis of developed concepts of hemming operation is done using the standard AutoForm-Incremental solver. Submesh strategy and special algorithm for contact description between inner and outer parts were implemented to ensure that accurate simulation results can be obtained within reasonable calculation time. Performance of the new software tool for hemming planning and accuracy of simulation results are demonstrated using several simple benchmarks and a real industrial part. It is shown that the new software tool can help to secure the efficient production launch by providing adequate support in try-out phase.
ANALYSIS ON IMPACT RESPONSES OF UNRESTRAINED PLANAR FRAME STRUCTURE(Ⅱ)-NUMERICAL EXAMPLE ANALYSIS
CHEN Rong; ZHENG Hai-tao; XUE Song-tao; TANG He-sheng
2005-01-01
By using the formula derived in Part (Ⅰ), the instant response of an unrestrained planar frame structure subjected to the impact of a moving rigid-body are evaluated and analysed.The impact force-time history between the structure and the moving rigid-body, shear force and bending moment distribution along the beams, axial force distribution along the bars were calculated. The wave propagation phenomena of the longitudinal wave in the bars, the flexural and shear waves in the beams were also analysed. The numerical results show that the time duration of impact force is controlled by the flexural wave and the longitudinal wave; the shear effect in beams should not be neglected in the impact response analysis of structures.
Numerical Bifurcation Methods and their Application to Fluid Dynamics: Analysis beyond Simulation
Dijkstra, Henk A.
2014-01-01
We provide an overview of current techniques and typical applications of numerical bifurcation analysis in fluid dynamical problems. Many of these problems are characterized by high-dimensional dynamical systems which undergo transitions as parameters are changed. The computation of the critical conditions associated with these transitions, popularly referred to as 'tipping points', is important for understanding the transition mechanisms. We describe the two basic classes of methods of numer...
An Efficient Method for Solving Spread Option Pricing Problem: Numerical Analysis and Computing
R. Company
2016-01-01
Full Text Available This paper deals with numerical analysis and computing of spread option pricing problem described by a two-spatial variables partial differential equation. Both European and American cases are treated. Taking advantage of a cross derivative removing technique, an explicit difference scheme is developed retaining the benefits of the one-dimensional finite difference method, preserving positivity, accuracy, and computational time efficiency. Numerical results illustrate the interest of the approach.
Geometric invariants for initial data sets: analysis, exact solutions, computer algebra, numerics
Valiente Kroon, Juan A, E-mail: j.a.valiente-kroon@qmul.ac.uk [School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London, E1 4NS (United Kingdom)
2011-09-22
A personal perspective on the interaction of analytical, numerical and computer algebra methods in classical Relativity is given. This discussion is inspired by the problem of the construction of invariants that characterise key solutions to the Einstein field equations. It is claimed that this kind of ideas will be or importance in the analysis of dynamical black hole spacetimes by either analytical or numerical methods.
Numerical methods for two-parameter local bifurcation analysis of maps
Govaerts, W.; Khoshsiar Ghaziani, R.; Kuznetsov, Yu.A.; Meijer, H.G.E.
2007-01-01
We discuss new and improved algorithms for the bifurcation analysis of fixed points and periodic orbits (cycles) of maps and their implementation in matcont, a MATLAB toolbox for continuation and bifurcation analysis of dynamical systems. This includes the numerical continuation of fixed points of i
Case study of small harbor excitation under storm and tsunami conditions
Synolakis, Costas; Maravelakis, Nikos; Kalligeris, Nikos; Skanavis, Vassilios; Kanoglu, Utku; Yalciner, Ahmet; Lynett, Pat
2016-04-01
enough information to infer the resonant modes of the basins excited during storm conditions. The deployment position of the pressure gauges is based on numerical modeling results. We have employed the fully nonlinear Boussinesq module of COULWAVE using a high resolution (2m cell size) relief model and an idealized TMA directional wave spectrum. The wave field and low frequency energy distribution in the basin are captured by both numerical modeling and field measurements. The field measurements agree well with the numerical modeling analysis, providing insight as to the causes of severe disturbance and useful information that should be considered for an effective solution to the protection of the harbor. Our measurements appear the first ever nearshore measurements of waves and currents for a 2+ year period duration in Greece. The work is also being used for validation tsunami inundation models for civil defense applications in Crete. * This work was supported by the project ASTARTE, Grant no 603839 7th FP (ENV.213.6.4.3) to the Technical University of Crete and to the Middle East Technical University.
Keen, A. S.; Lynett, P. J.; Ayca, A.
2016-12-01
Because of the damage resulting from the 2010 Chile and 2011 Japanese tele-tsunamis, the tsunami risk to the small craft marinas in California has become an important concern. The talk will outline an assessment tool which can be used to assess the tsunami hazard to small craft harbors. The methodology is based on the demand and structural capacity of the floating dock system, composed of floating docks/fingers and moored vessels. The structural demand is determined using a Monte Carlo methodology. Monte Carlo methodology is a probabilistic computational tool where the governing might be well known, but the independent variables of the input (demand) as well as the resisting structural components (capacity) may not be completely known. The Monte Carlo approach uses a distribution of each variable, and then uses that random variable within the described parameters, to generate a single computation. The process then repeats hundreds or thousands of times. The numerical model "Method of Splitting Tsunamis" (MOST) has been used to determine the inputs for the small craft harbors within California. Hydrodynamic model results of current speed, direction and surface elevation were incorporated via the drag equations to provide the bases of the demand term. To determine the capacities, an inspection program was developed to identify common features of structural components. A total of six harbors have been inspected ranging from Crescent City in Northern California to Oceanside Harbor in Southern California. Results from the inspection program were used to develop component capacity tables which incorporated the basic specifications of each component (e.g. bolt size and configuration) and a reduction factor (which accounts for the component reduction in capacity with age) to estimate in situ capacities. Like the demand term, these capacities are added probabilistically into the model. To date the model has been applied to Santa Cruz Harbor as well as Noyo River. Once
ERROR ANALYSIS FOR A FAST NUMERICAL METHOD TO A BOUNDARY INTEGRAL EQUATION OF THE FIRST KIND
Jingtang Ma; Tao Tang
2008-01-01
For two-dimensional boundary integral equations of the first kind with logarithmic kernels,the use of the conventional boundary element methods gives linear systems with dense matrix.In a recent work [J.Comput.Math.,22 (2004),pp.287-298],it is demonstrated that the dense matrix can be replaced by a sparse one if appropriate graded meshes are used in the quadrature rules.The numerical experiments also indicate that the proposed numerical methods require less computational time than the conventional ones while the formal rate of convergence can be preserved.The purpose of this work is to establish a stability and convergence theory for this fast numerical method.The stability analysis depends on a decomposition of the coefficient matrix for the collocation equation.The formal orders of convergence observed in the numerical experiments are proved rigorously.
Numerical analysis of the steam flow field in shell and tube heat exchanger
Bartoszewicz Jarosław
2016-06-01
Full Text Available In the paper, the results of numerical simulations of the steam flow in a shell and tube heat exchanger are presented. The efficiency of different models of turbulence was tested. In numerical calculations the following turbulence models were used: k-ε, RNG k-ε, Wilcox k-ω, Chen-Kim k-ε, and Lam-Bremhorst k-ε. Numerical analysis of the steam flow was carried out assuming that the flow at the inlet section of the heat exchanger were divided into three parts. The angle of steam flow at inlet section was determined individually in order to obtain the best configuration of entry vanes and hence improve the heat exchanger construction. Results of numerical studies were verified experimentally for a real heat exchanger. The modification of the inlet flow direction according to theoretical considerations causes the increase of thermal power of a heat exchanger of about 14%.
Numerical analysis of the steam flow field in shell and tube heat exchanger
Bartoszewicz, Jarosław; Bogusławski, Leon
2016-06-01
In the paper, the results of numerical simulations of the steam flow in a shell and tube heat exchanger are presented. The efficiency of different models of turbulence was tested. In numerical calculations the following turbulence models were used: k-ɛ, RNG k-ɛ, Wilcox k-ω, Chen-Kim k-ɛ, and Lam-Bremhorst k-ɛ. Numerical analysis of the steam flow was carried out assuming that the flow at the inlet section of the heat exchanger were divided into three parts. The angle of steam flow at inlet section was determined individually in order to obtain the best configuration of entry vanes and hence improve the heat exchanger construction. Results of numerical studies were verified experimentally for a real heat exchanger. The modification of the inlet flow direction according to theoretical considerations causes the increase of thermal power of a heat exchanger of about 14%.
Solutions manual to accompany An introduction to numerical methods and analysis
Epperson, James F
2014-01-01
A solutions manual to accompany An Introduction to Numerical Methods and Analysis, Second Edition An Introduction to Numerical Methods and Analysis, Second Edition reflects the latest trends in the field, includes new material and revised exercises, and offers a unique emphasis on applications. The author clearly explains how to both construct and evaluate approximations for accuracy and performance, which are key skills in a variety of fields. A wide range of higher-level methods and solutions, including new topics such as the roots of polynomials, sp
Nonlinear Scaling Laws for Parametric Receiving Arrays. Part II. Numerical Analysis
1976-06-30
8217" " .’Ml’.1 ’.■■’: ■ ’ ^ t- Nonlinear Scaling Laws for Parametric Receiving Arrays Part II Numerical Analysis » - m • o prepared ...8217 ’ ■ — Nonlinear Scaling Laws for Parametric Receiving Arrays » z Part II. Numerical Analysis prepared under: A ——^ N0ÖJ339- 7 5 - C -J02 59, //V-ARPA Order...IF ’IP ,6T, 10 .HNO. IR .I_E. £0> riELTI = LiELTrJ IF ’IP .GT. 3 0 .HMD. IP .LE. 3 0;. [ IELT I = IiELT3 IF
Measurement of the Operating Parameters and Numerical Analysis of the Mechanical Subsystem
Božek, Pavol; Turygin, Yuri
2014-08-01
Submission is focused on completing the information system about quality, operation, automatic testing and new evaluating method of vehicle subsystem. Numeric analysis is carried out on the base of automatic collection and systematic recording of commercial car operation. Proposed new information system about operation and trial process allows verification according to the proposed method. Critical components verified in laboratory conditions are detected by numeric analysis of reliability. Quality level increasing not only for final product, but also related automatic test laboratory for cars is the result of respecting these principles.
Measurement of the Operating Parameters and Numerical Analysis of the Mechanical Subsystem
Božek Pavol
2014-08-01
Full Text Available Submission is focused on completing the information system about quality, operation, automatic testing and new evaluating method of vehicle subsystem. Numeric analysis is carried out on the base of automatic collection and systematic recording of commercial car operation. Proposed new information system about operation and trial process allows verification according to the proposed method. Critical components verified in laboratory conditions are detected by numeric analysis of reliability. Quality level increasing not only for final product, but also related automatic test laboratory for cars is the result of respecting these principles.
Surgidero de Batabanó Harbor, Cuba
Hopmans, R.; Van Kessel, L.; Lendering, K.; Oud, M.; Tromp, R.
2011-01-01
The harbor of Surgidero de Batabano is a harbor that lies in the Gulf of Batabano in the South-Western part of Cuba. It serves as a connection between the main land of Cuba and the islands 'Isla de la Juventud' and Cayo Largo. The Batabano harbor suffers from sediment accretion. The accretion of sed
Surgidero de Batabanó Harbor, Cuba
Hopmans, R.; Van Kessel, L.; Lendering, K.; Oud, M.; Tromp, R.
2011-01-01
The harbor of Surgidero de Batabano is a harbor that lies in the Gulf of Batabano in the South-Western part of Cuba. It serves as a connection between the main land of Cuba and the islands 'Isla de la Juventud' and Cayo Largo. The Batabano harbor suffers from sediment accretion. The accretion of
Harbor Expansion Facilitates Crude and Petrochemicals Transportation
无
2003-01-01
@@ Douwei Harbor attracting petrochem investment Substantial progress has been made in the preliminary preparation of Douwei Harbor project in Hui'an, Fujian Province. It is one of the major four transfer ports in China planned by the Ministry of Transportation. A number of projects, with a total investment approaching 10 billion yuan,will come under construction in the harbor zone.
Numerical analysis of dynamic variation of weld pool geometry in fully-penetrated TIG welding
Zhao Ming; Li Ruiying
2008-01-01
A mathematical model is developed for numerical analysis of thermal process in TIG welding with a moving arc, which is considered the double-elliptic distribution for both arc heat flux and arc pressure. An adjusting factor is introduced into the expression of arc pressure. The domain within which the arc heat flux is distributed non-symmetrically due to arc moving is selected appropriately, and three conditions for the domain to meet are described. The latent heat is taken into consideration by liquid fraction method. The dynamic development of weld pool geometry during TIG welding is analyzed numerically, and the effect of arc moving on the weld pool geometry is discussed. The experimental results show that the numerical analysis accuracy is obviously improved through taking the above-mentioned measures.
Knowledge based recognition of harbor target
Zhu Bing; Li Jinzong; Cheng Aijun
2006-01-01
A fast knowledge based recognition method of the harbor target in large gray remote-sensing image is presented. First, the distributed features and the inherent feature are analyzed according to the knowledge of harbor targets; then, two methods for extracting the candidate region of harbor are devised in accordance with different sizes of the harbors; after that, thresholds are used to segment the land and the sea with strategies of the segmentation error control; finally, harbor recognition is implemented according to its inherent character (semi-closed region of seawater).
Influences of system uncertainties on the numerical transfer path analysis of engine systems
Acri, A.; Nijman, E.; Acri, A.; Offner, G.
2017-10-01
Practical mechanical systems operate with some degree of uncertainty. In numerical models uncertainties can result from poorly known or variable parameters, from geometrical approximation, from discretization or numerical errors, from uncertain inputs or from rapidly changing forcing that can be best described in a stochastic framework. Recently, random matrix theory was introduced to take parameter uncertainties into account in numerical modeling problems. In particular in this paper, Wishart random matrix theory is applied on a multi-body dynamic system to generate random variations of the properties of system components. Multi-body dynamics is a powerful numerical tool largely implemented during the design of new engines. In this paper the influence of model parameter variability on the results obtained from the multi-body simulation of engine dynamics is investigated. The aim is to define a methodology to properly assess and rank system sources when dealing with uncertainties. Particular attention is paid to the influence of these uncertainties on the analysis and the assessment of the different engine vibration sources. Examples of the effects of different levels of uncertainties are illustrated by means of examples using a representative numerical powertrain model. A numerical transfer path analysis, based on system dynamic substructuring, is used to derive and assess the internal engine vibration sources. The results obtained from this analysis are used to derive correlations between parameter uncertainties and statistical distribution of results. The derived statistical information can be used to advance the knowledge of the multi-body analysis and the assessment of system sources when uncertainties in model parameters are considered.
Numerical analysis and optimization of a dual-order mode all-optical wavelength converter
Nielsen, Mads Lønstrup; Wolfson, David; Kloch, Allan;
2001-01-01
A numerical analysis of a dual-order mode (DOMO) wavelength converter has been carried out. We optimize the waveguide dimensions for high speed and compare to a single mode device. We also identify a crosstalk penalty when converting to wavelengths close to the original....
Ona, Stephen L.W.; Harringtona, Clare S.
2000-01-01
Amplified fragment length polymorphism (AFLP)-based profiling was performed on 138 strains representing all named Campylobacter species and subspecies. Profiles of 15/16 species comprised 6 to greater than 100 fragments and were subjected to numerical analysis. The mean similarity of 48 duplicate...
Numerical Bifurcation Methods and their Application to Fluid Dynamics: Analysis beyond Simulation
Dijkstra, H.A.; Wubs, F.W.; et al, [No Value; Thiele, U.
2014-01-01
We provide an overview of current techniques and typical applications of numerical bifurcation analysis in fluid dynamical problems. Many of these problems are characterized by high-dimensional dynamical systems which undergo transitions as parameters are changed. The computation of the critical con
Research in progress in applied mathematics, numerical analysis, and computer science
1990-01-01
Research conducted at the Institute in Science and Engineering in applied mathematics, numerical analysis, and computer science is summarized. The Institute conducts unclassified basic research in applied mathematics in order to extend and improve problem solving capabilities in science and engineering, particularly in aeronautics and space.
Numerical Bifurcation Methods and their Application to Fluid Dynamics : Analysis beyond Simulation
Dijkstra, Henk A.; Wubs, Fred W.; Cliffe, Andrew K.; Doedel, Eusebius; Dragomirescu, Ioana F.; Eckhardt, Bruno; Gelfgat, Alexander Yu.; Hazel, Andrew L.; Lucarini, Valerio; Salinger, Andy G.; Phipps, Erik T.; Sanchez-Umbria, Juan; Schuttelaars, Henk; Tuckerman, Laurette S.; Thiele, Uwe
2014-01-01
We provide an overview of current techniques and typical applications of numerical bifurcation analysis in fluid dynamical problems. Many of these problems are characterized by high-dimensional dynamical systems which undergo transitions as parameters are changed. The computation of the critical con
Gomez Ros, J. M.; Delgado, A.
1989-07-01
This report presents a method for the numerical analysis of complex thermoluminescence glow curves resolving the individual glow peak components. The method employs first order kinetics analytical expressions and is based In a Marquart-Levenberg minimization procedure. A simplified version of this method for thermoluminescence dosimetry (TLD) is also described and specifically developed to operate whit Lithium Fluoride TLD-100. (Author). 36 refs.
Kargul T.
2015-04-01
Full Text Available Measurement of thermophysical properties of steel is possible by using different thermal analysis techniques. In the field of metallurgy the most relevant methods are Differential Thermal Analysis (DTA and Differential Scanning Calorimetry (DSC. The paper presents the results of thermophysical properties which are necessary to carry out numerical simulation of continuous casting of steel. The study was performed for two steel grades S320GD and S235JR. The main aim of the research was to determine the dependence of specific heat on temperature. On the basis of obtained results the thermal effects of phase transformations and characteristic transition temperatures were also identified. Both the specific heat of steel and thermal effects of phase transformations are included in the Fourier-Kirchhoff equation, as the material properties necessary to obtain the numerical solution. The paper presents the research methodology, analysis of results and method of determining the specific heat of steel based on the results of DSC analysis.
33 CFR 80.1122 - Channel Islands Harbor, CA.
2010-07-01
...) A line drawn from Channel Islands Harbor South Jetty Light 2 to Channel Islands Harbor Breakwater South Light 1. (b) A line drawn from Channel Islands Harbor Breakwater North Light to Channel Islands Harbor North Jetty Light 5....
About numerical analysis of electromagnetic field induce in gear wheels during hardening process
Gabriel Cheregi
2008-05-01
Full Text Available The paper presents the results of a numericalsimulation using finite element analysis for a coupledmagneto-thermal problem, specific for inductionhardening processes. The analysis takes into account therelative movement between inductor and the heated part.Numerical simulation allows to determine accurately thethermal regime of the induction heating process and theoptimal parameters which offer maximum efficiency.Therefore the experiments number in designing processcan be decreased and a better knowledge of the processcan be obtained.
Kavetski, D.; Clark, M. P.; Fenicia, F.
2011-12-01
Hydrologists often face sources of uncertainty that dwarf those normally encountered in many engineering and scientific disciplines. Especially when representing large scale integrated systems, internal heterogeneities such as stream networks, preferential flowpaths, vegetation, etc, are necessarily represented with a considerable degree of lumping. The inputs to these models are themselves often the products of sparse observational networks. Given the simplifications inherent in environmental models, especially lumped conceptual models, does it really matter how they are implemented? At the same time, given the complexities usually found in the response surfaces of hydrological models, increasingly sophisticated analysis methodologies are being proposed for sensitivity analysis, parameter calibration and uncertainty assessment. Quite remarkably, rather than being caused by the model structure/equations themselves, in many cases model analysis complexities are consequences of seemingly trivial aspects of the model implementation - often, literally, whether the start-of-step or end-of-step fluxes are used! The extent of problems can be staggering, including (i) degraded performance of parameter optimization and uncertainty analysis algorithms, (ii) erroneous and/or misleading conclusions of sensitivity analysis, parameter inference and model interpretations and, finally, (iii) poor reliability of a calibrated model in predictive applications. While the often nontrivial behavior of numerical approximations has long been recognized in applied mathematics and in physically-oriented fields of environmental sciences, it remains a problematic issue in many environmental modeling applications. Perhaps detailed attention to numerics is only warranted for complicated engineering models? Would not numerical errors be an insignificant component of total uncertainty when typical data and model approximations are present? Is this really a serious issue beyond some rare isolated
Characterization of Tunisian marine sediments in Rades and Gabes harbors
Imen BEL HADJ ALI; Zoubeir LAFHAJ; Mounir BOUASSIDA; Imen SAID
2014-01-01
The objective of this article is to study the geotechnical and environmental characteristics of sediments dredged from two Tunisian harbors:Rades and Gabes. The first harbor represents the main facility place in the national transport chain. The second one is selected as its sediments present a serious ecological constraint caused by the discharge of wastes into the marine environment. These sediments are either discarded at sea or landfilled despite their harmful effects on the environment. The article is divided into three main sections. The first one presents the material that was carried for Rades and Gabes harbors. The conservation conditions and the used experimental tests are detailed. Geotechnical characterization includes the determination of the grain size distribution, the water content, the Atterberg limits, the methylene blue value, the specific area, the bulk density, the specific unit weight, the organic and carbonate contents. Environmental characterization is assessed by the determination of metals concentrations in a leaching solution. The second section deals with the description and analysis of geotechnical properties of Rades and Gabes harbors’ sediments. The results obtained show that Rades harbor sediments are slightly sandy clayey silts whereas Gabes harbor sediments are silty sands characterized by a highly plastic clay fraction. Both of the two sediments don’t exhibit a high organic content. Finally, chemical, mineralogical and environmental properties are presented and then analysed. The experimental results obtained show that Rades and Gabes sediments could be used as a sand substitute in the formulation of a new construction material. Gabes harbor sediments are more polluted than Rades harbor sediments.
Heat Transfer in a Porous Radial Fin: Analysis of Numerically Obtained Solutions
R. Jooma
2017-01-01
Full Text Available A time dependent nonlinear partial differential equation modelling heat transfer in a porous radial fin is considered. The Differential Transformation Method is employed in order to account for the steady state case. These solutions are then used as a means of assessing the validity of the numerical solutions obtained via the Crank-Nicolson finite difference method. In order to engage in the stability of this scheme we conduct a stability and dynamical systems analysis. These provide us with an assessment of the impact of the nonlinear sink terms on the stability of the numerical scheme employed and on the dynamics of the solutions.
Bergan, T; Niemelä, T; Gyllenberg, H
1975-06-01
A computer-based numerical approach to the allocation of Pseudomonas aeruginosa bacteriphage patterns has been presented. This rendered a usefule identification of similar phage types. The grouping had epidemiological relevance. Grouping of phage typing patterns of P. aeruginosa by numerical analysis showed that the patterns of related isolations may differ in one strong lysotype reaction, occasionally even in more reactions. Thus parallels previous findings which have been based on studies of the reproducibility of the method and evaluations of differences in epidemiologically related strains from the same sources.
1994-01-01
This report summarizes research conducted at the Institute for Computer Applications in Science and Engineering in applied mathematics, fluid mechanics, and computer science during the period October 1, 1993 through March 31, 1994. The major categories of the current ICASE research program are: (1) applied and numerical mathematics, including numerical analysis and algorithm development; (2) theoretical and computational research in fluid mechanics in selected areas of interest to LaRC, including acoustics and combustion; (3) experimental research in transition and turbulence and aerodynamics involving LaRC facilities and scientists; and (4) computer science.
CAREFUL NUMERICAL SIMULATION AND ANALYSIS OF MIGRATION-ACCUMULATION OF TANHAI REGION
YUAN Yi-rang; DU Ning; HAN Yu-ji
2005-01-01
Numerical simulation of careful parallel arithmetic of oil resources migration-accumulation of Tanhai Region (three-layer) was done. Careful parallel operator splitting-up implicit iterative scheme, parallel arithmetic program, parallel arithmetic information and alternating-direction mesh subdivision were put forward. Parallel arithmetic and analysis of different CPU combinations were done. This numerical simulation test and the actual conditions are basically coincident. The convergence estimation of the model problem has successfully solved the difficult problem in the fields of permeation fluid mechanics, computational mathematics and petroleum geology.
Numerical analysis of secondary flow in a two-stage turbine
Kirtley, K. R.; Beach, T. A.; Adamczyk, J. J.
1990-01-01
The three-dimensional viscous average passage flow in the Pratt and Whitney alternate design Space Shuttle Main Engine fuel turbine has been simulated. The effect of secondary flows generated by upstream blade rows on the performance of downstream blade rows is studied. The numerical results are compared to the design intent to validate improved models in the average passage equations. Analysis of the results centers on the primary spanwise mixing mechanism in this low aspect ratio turbine. A multigrid method has also been incorporated to improve the overall convergence rate of the numerical algorithm.
Rolland Andrade
2014-01-01
Full Text Available In hard rock terrain, fractured aquifers comprise the major source of groundwater availability where the phreatic aquifer is desaturated. Identification of fracture zones in hard rock terrain and potential groundwater source delineation had been a perennial problem in hydrology. The purpose of this paper is to highlight the study over a small watershed area, in a granite terrain, wherein an attempt was made to delineate and map the fractured aquifer using numerical (factor analysis of the conventional vertical electrical sounding data, which was obscure in curve matching technique. This numerical approach in concatenation with resistivity imaging or other techniques would prove to be an effective tool in groundwater exploration.
Griffiths, Graham
2010-01-01
Although the Partial Differential Equations (PDE) models that are now studied are usually beyond traditional mathematical analysis, the numerical methods that are being developed and used require testing and validation. This is often done with PDEs that have known, exact, analytical solutions. The development of analytical solutions is also an active area of research, with many advances being reported recently, particularly traveling wave solutions for nonlinear evolutionary PDEs. Thus, the current development of analytical solutions directly supports the development of numerical methods by p
Electrokinetic Particle Transport in Micro-Nanofluidics Direct Numerical Simulation Analysis
Qian, Shizhi
2012-01-01
Numerous applications of micro-/nanofluidics are related to particle transport in micro-/nanoscale channels, and electrokinetics has proved to be one of the most promising tools to manipulate particles in micro/nanofluidics. Therefore, a comprehensive understanding of electrokinetic particle transport in micro-/nanoscale channels is crucial to the development of micro/nano-fluidic devices. Electrokinetic Particle Transport in Micro-/Nanofluidics: Direct Numerical Simulation Analysis provides a fundamental understanding of electrokinetic particle transport in micro-/nanofluidics involving elect
Sensitivity of a numerical wave model on wind re-analysis datasets
Lavidas, George; Venugopal, Vengatesan; Friedrich, Daniel
2017-03-01
Wind is the dominant process for wave generation. Detailed evaluation of metocean conditions strengthens our understanding of issues concerning potential offshore applications. However, the scarcity of buoys and high cost of monitoring systems pose a barrier to properly defining offshore conditions. Through use of numerical wave models, metocean conditions can be hindcasted and forecasted providing reliable characterisations. This study reports the sensitivity of wind inputs on a numerical wave model for the Scottish region. Two re-analysis wind datasets with different spatio-temporal characteristics are used, the ERA-Interim Re-Analysis and the CFSR-NCEP Re-Analysis dataset. Different wind products alter results, affecting the accuracy obtained. The scope of this study is to assess different available wind databases and provide information concerning the most appropriate wind dataset for the specific region, based on temporal, spatial and geographic terms for wave modelling and offshore applications. Both wind input datasets delivered results from the numerical wave model with good correlation. Wave results by the 1-h dataset have higher peaks and lower biases, in expense of a high scatter index. On the other hand, the 6-h dataset has lower scatter but higher biases. The study shows how wind dataset affects the numerical wave modelling performance, and that depending on location and study needs, different wind inputs should be considered.
Cold spring harbor symposia on quantitative biology
1988-01-01
For many decades, it has been clear that cells have a multitude of ways of sensing their environment and converting a plethora of external signals into measured intracellular responses. Now we realize that many first messengers do not act directly through second messengers, but instead work at the genetic level by binding to cytoplasmically located receptors, which can then bind to DNA and turn on or off the functioning of specific genes. Today, we refer to the way that external signals are passed through various cellular components as signal transduction processes, with receptors and their associated molecules known as biological transducers. Because most transducer molecules are present in very limited amounts, their study at the biochemical level until recently was at best difficult, and hypotheses as to how they functioned were almost impossible to test rigorously. Today, recombinant DNA techniques have dramatically changed the picture. Even very rare receptors are now open to analysis if their respective genes can be cloned, and virtually every month the amino acid sequence of a new key biological transducer is established. The time was thus appropriate last June to hold a Cold Spring Harbor Symposium on the Molecular Biology of Signal Transduction. The final program consisted of 119 speakers, who spoke before an audience of 439, the largest ever yet to attend a Cold Spring Harbor Symposium. This volume contains 54 papers. Individual papers are indexed separately on the energy data base.
Juan WANG; Wenqin SONG
2009-01-01
The majority of single nucleotide polymorphisms (SNPs) found in the coding region (cSNPs) are single base substitutions that may or may not lead to amino acid substitutions,most of which are related to diseases.Some cSNPs may prove useful for their potential links to functional cSNPs via linkage disequilibrium mapping.We have selected 48 cSNPs located in the coding regions of 25 genes to construct the cSNP chip.These genes are harbored in the high frequency loss regions of the chromosome 1p and 8p and related with apoptosis,cell cycles,signal transduction,oncogene,tumor suppressor genes and so on.All of the cSNPs can lead to amino acid substitutions except TP73 (rs1801174).The PCR products amplified from 31 hepatocellular carcinoma (HCC) specimens were labeled with Dig-dUTP and then hybridized with the cSNP chips.The results showed that there was no hybridization signal when there was more than one site of mutation in the amplification sequence,indicating that the cSNP chip had a high sensitivity.The statistic data of the SNP (MT,homozygous and HT,heterozygous) in the HCC patients with different phenotypes (HBV +/-,differentiation stage,family history positive or negative,tumor size) indicated that the number of MT was distinctly different between patients with positive HBV and negative HBV.The MT and HT numbers of all the 48 cSNPs were significantly different between low differentiation and high differentiation HCC patients.The numbers of MT and HT were not different between positived and negative family history groups and between tumor size＞3 cm and≤3 cm groups.The study results provided useful information for understanding the molecular mechanisms of HCC development.
CHENMing; TANGTiantong; ZHANGXiaolin
2003-01-01
In this paper, an effective numerical method based on wavelet moment method is presented to enhance the analysis of interdigital transducer (IDT)for the excitation of surface acoustic waves (SAW) on the piezoelectric substrate of acoustic-optical devices. This problem is formulated in terms of an integral equa-tion, and its electric charge matrix equations obtained by the method of moment (MoM) are effectively solved by Daubechies discrete wavelet transform. One of the mosts triking advantage of this method is that it can greatly ac-celerate the computing with the help of conjugate gradient methods because the wavelet transform make the moment matrices sparse. As a result of the use of this method, the transducer input power coupling factors to both surface and bulk waves are computed. Analysis results show this method is a powerful numerical technique in analysis of IDT for acousto-optical devices.
On the use of stability regions in the numerical analysis of initial value problems
Lenferink, H. W. J.; Spijker, M. N.
1991-07-01
This paper deals with the stability analysis of one-step methods in the numerical solution of initial (-boundary) value problems for linear, ordinary, and partial differential equations. Restrictions on the stepsize are derived which guarantee the rate of error growth in these methods to be of moderate size. These restrictions are related to the stability region of the method and to numerical ranges of matrices stemming from the differential equation under consideration. The errors in the one-step methods are measured in arbitrary norms (not necessarily generated by an inner product). The theory is illustrated in the numerical solution of the heat equation and some other differential equations, where the error growth is measured in the maximum norm.
Numerical Analysis of Dynamic Behavior of RC Slabs Under Blast Loading
DU Hao; LI Zhongxian
2009-01-01
In Order to reduce economic and life losses due to terrorism or accidental explosion threats,reinforced concrete(RC)slabs of buildings need to be designed or retrofitted to resist blast loading.In this paper the dynamic behavior Of RC slabs under blast loading and its influencing factors are studied.The numerical model of an RC slab subjected to blast loading is established using the explicit dynamic analysis software.Both the strain rate effect and the damage accumulation are taken into account in the material model.The dynamic responses of the RC slab subiected to blast loading are analyzed,and the influence of concrete strength,thickness and reinforcement ratio on the behavior of the RC slab under blast loading iS numerically investigated.Based on the numerical results.some principles for blast-resistant design and retrofitting are proposed to improve the behavior of the RC slab subjected to blast loading.
Stability Analysis of Numerical Methods for a 1.5-Layer Shallow-Water Ocean Model
Guang-an Zou
2013-01-01
Full Text Available A 1.5-layer reduced-gravity shallow-water ocean model in spherical coordinates is described and discretized in a staggered grid (standard Arakawa C-grid with the forward-time central-space (FTCS method and the Leap-frog finite difference scheme. The discrete Fourier analysis method combined with the Gershgorin circle theorem is used to study the stability of these two finite difference numerical models. A series of necessary conditions of selection criteria for the time-space step sizes and model parameters are obtained. It is showed that these stability conditions are more accurate than the Courant-Friedrichs-Lewy (CFL condition and other two criterions (Blumberg and Mellor, 1987; Casulli, 1990, 1992. Numerical experiments are proposed to test our stability results, and numerical model that is designed is also used to simulate the ocean current.
System Level Numerical Analysis of a Monte Carlo Simulation of the E. Coli Chemotaxis
Siettos, Constantinos I
2010-01-01
Over the past few years it has been demonstrated that "coarse timesteppers" establish a link between traditional numerical analysis and microscopic/ stochastic simulation. The underlying assumption of the associated lift-run-restrict-estimate procedure is that macroscopic models exist and close in terms of a few governing moments of microscopically evolving distributions, but they are unavailable in closed form. This leads to a system identification based computational approach that sidesteps the necessity of deriving explicit closures. Two-level codes are constructed; the outer code performs macroscopic, continuum level numerical tasks, while the inner code estimates -through appropriately initialized bursts of microscopic simulation- the quantities required for continuum numerics. Such quantities include residuals, time derivatives, and the action of coarse slow Jacobians. We demonstrate how these coarse timesteppers can be applied to perform equation-free computations of a kinetic Monte Carlo simulation of...
Model and numerical analysis of 3D corrosion layer of reinforced concrete structure
李永和; 葛修润
2003-01-01
Under the assumption that the corrosion at the end of steel bolt or steel bar is shaped like the contour line of ellipsoid, a mathematic model and formulas of calculating the thickness of corrosion layer at arbitrary point are presented in this paper. Then regarding the arbitrary points of 3D corrosion layer as patch element model of fictitious displacement discontinuity, we propose the basic solution of 3D problem of the patch element acting on discontinuous displacement. With three basic assumptions of the corrosion layer, we set up the 3D numerical discreted model, and derive the stress boundary equation for fictitious corrosion layer of 3D numerical analysis. We also make the numerical stimulating calculation of the shotcrete structure at some lane using 3D finite element method. The results show that this method is effective and reasonable.
LIU Zong-Liang; ZHAO Fang; LI Shao-Hua; ZHAO Mei-Shan; CHEN Chang-Yong
2008-01-01
This paper is concerned with the determination of a unique scaling parameter in complex scaling analysis and with accurate calculation of dynamics resonances. In the preceding paper we have presented a theoretical analysis and provided a formalism for dynamical resonance calculations. In this paper we present accurate numerical results for two non-trivial dynamical processes, namely, models of diatomie molecular predissoeiation and of barrier potential scattering for resonances. The results presented in this paper confirm our theoretical analysis, remove a theoretical ambiguity on determination of the complex scaling parameter, and provide an improved understanding for dynamical resonance calculations in rigged Hilbert space.
Development of a numerical model for vehicle-bridge interaction analysis of railway bridges
Kim, Hee Ju; Cho, Eun Sang; Ham, Jun Su; Park, Ki Tae; Kim, Tae Heon
2016-04-01
In the field of civil engineering, analyzing dynamic response was main concern for a long time. These analysis methods can be divided into moving load analysis method and moving mass analysis method, and formulating each an equation of motion has recently been studied after dividing vehicles and bridges. In this study, the numerical method is presented, which can consider the various train types and can solve the equations of motion for a vehicle-bridge interaction analysis by non-iteration procedure through formulating the coupled equations for motion. Also, 3 dimensional accurate numerical models was developed by KTX-vehicle in order to analyze dynamic response characteristics. The equations of motion for the conventional trains are derived, and the numerical models of the conventional trains are idealized by a set of linear springs and dashpots with 18 degrees of freedom. The bridge models are simplified by the 3 dimensional space frame element which is based on the Euler-Bernoulli theory. The rail irregularities of vertical and lateral directions are generated by PSD functions of the Federal Railroad Administration (FRA).
Zhou, Xiafeng, E-mail: zhou-xf11@mails.tsinghua.edu.cn; Guo, Jiong, E-mail: guojiong12@tsinghua.edu.cn; Li, Fu, E-mail: lifu@tsinghua.edu.cn
2015-12-15
Highlights: • NEMs are innovatively applied to solve convection diffusion equation. • Stability, accuracy and numerical diffusion for NEM are analyzed for the first time. • Stability and numerical diffusion depend on the NEM expansion order and its parity. • NEMs have higher accuracy than both second order upwind and QUICK scheme. • NEMs with different expansion orders are integrated into a unified discrete form. - Abstract: The traditional finite difference method or finite volume method (FDM or FVM) is used for HTGR thermal-hydraulic calculation at present. However, both FDM and FVM require the fine mesh sizes to achieve the desired precision and thus result in a limited efficiency. Therefore, a more efficient and accurate numerical method needs to be developed. Nodal expansion method (NEM) can achieve high accuracy even on the coarse meshes in the reactor physics analysis so that the number of spatial meshes and computational cost can be largely decreased. Because of higher efficiency and accuracy, NEM can be innovatively applied to thermal-hydraulic calculation. In the paper, NEMs with different orders of basis functions are successfully developed and applied to multi-dimensional steady convection diffusion equation. Numerical results show that NEMs with three or higher order basis functions can track the reference solutions very well and are superior to second order upwind scheme and QUICK scheme. However, the false diffusion and unphysical oscillation behavior are discovered for NEMs. To explain the reasons for the above-mentioned behaviors, the stability, accuracy and numerical diffusion properties of NEM are analyzed by the Fourier analysis, and by comparing with exact solutions of difference and differential equation. The theoretical analysis results show that the accuracy of NEM increases with the expansion order. However, the stability and numerical diffusion properties depend not only on the order of basis functions but also on the parity of
Effect Of Turbulence Modelling In Numerical Analysis Of Melting Process In An Induction Furnace
Buliński P.
2015-09-01
Full Text Available In this paper, the velocity field and turbulence effects that occur inside a crucible of a typical induction furnace were investigated. In the first part of this work, a free surface shape of the liquid metal was measured in a ceramic crucible. Then a numerical model of aluminium melting process was developed. It took into account coupling of electromagnetic and thermofluid fields that was performed using commercial codes. In the next step, the sensitivity analysis of turbulence modelling in the liquid domain was performed. The obtained numerical results were compared with the measurement data. The performed analysis can be treated as a preliminary approach for more complex mathematical modelling for the melting process optimisation in crucible induction furnaces of different types.
Numerical analysis of seismic wave amplification in Nice (France) and comparisons with experiments
Semblat, Jean-François; Dangla, Patrick; 10.1016/S0267-7261(00)00016-6
2009-01-01
The analysis of site effects is very important since the amplification of seismic motion in some specific areas can be very strong. In this paper, the site considered is located in the centre of Nice on the French Riviera. Site effects are investigated considering a numerical approach (Boundary Element Method) and are compared to experimental results (weak motion and microtremors). The investigation of seismic site effects through numerical approaches is interesting because it shows the dependency of the amplification level on such parameters as wave velocity in surface soil layers, velocity contrast with deep layers, seismic wave type, incidence and damping. In this specific area of Nice, a one-dimensional (1D) analytical analysis of amplification does not give a satisfactory estimation of the maximum reached levels. A boundary element model is then proposed considering different wave types (SH, P, SV) as the seismic loading. The alluvial basin is successively assumed as an isotropic linear elastic medium an...
Numerical Analysis of the Stability of Embankment Slope Reinforced with Piles
CUI Wei; ZHANG Zhigeng; YAN Shuwang
2007-01-01
The effects of stabilizing piles on the stability of an embankment slope are analyzed by numerical simulation. The shear strength reduction method is used for the analysis, and the soil - pile interaction is simulated with zero-thickness elasto-plastic interface elements. Effects of pile spacing and pile position on the safety factor of slope and the behavior of piles under these conditions are given. The numerical analysis indicates that the positions of the pile have significant influence on the stability of the slope, and the pile needs to be installed in the middle of the slope for maximum safety factors. In the end, the soil arching effect closely associated with the space between stabilizing piles is analyzed. The results are helpful for design and construction of stabilizing piles.
Zhangxin Chen
1999-12-01
Full Text Available This is the third paper of a three-part series where we develop and analyze a finite element approximation for a degenerate elliptic-parabolic partial differential system which describes the flow of two incompressible, immiscible fluids in porous media. The approximation uses a mixed finite element method for the pressure equation and a Galerkin finite element method for the saturation equation. It is based on a regularization of the saturation equation. In the first paper cite{RckA} we analyzed the regularized differential system and presented numerical results. In the second paper cite{RckB} we obtained error estimates. In the present paper we describe a perturbation analysis for the saturation equation and numerical experiments for complementing this analysis.
Migórski, Stanisław; Sofonea, Mircea
2015-01-01
Highlighting recent advances in variational and hemivariational inequalities with an emphasis on theory, numerical analysis and applications, this volume serves as an indispensable resource to graduate students and researchers interested in the latest results from recognized scholars in this relatively young and rapidly-growing field. Particularly, readers will find that the volume’s results and analysis present valuable insights into the fields of pure and applied mathematics, as well as civil, aeronautical, and mechanical engineering. Researchers and students will find new results on well posedness to stationary and evolutionary inequalities and their rigorous proofs. In addition to results on modeling and abstract problems, the book contains new results on the numerical methods for variational and hemivariational inequalities. Finally, the applications presented illustrate the use of these results in the study of miscellaneous mathematical models which describe the contact between deformable bodies and a...
Numerical Analysis of Exergy for Air-Conditioning Influenced by Ambient Temperature
Jing-Nang Lee
2014-07-01
Full Text Available The article presents numerical analysis of exergy for air-conditioning influenced by ambient temperature. The model of numerical simulation uses an integrated air conditioning system exposed in varied ambient temperature to observe change of the four main devices, the compressor, the condenser, the capillary, and the evaporator in correspondence to ambient temperature. The analysis devices of the four devices’s exergy influenced by the varied ambient temperature and found that the capillary has unusual increasing exergy loss vs. increasing ambient temperature in comparison to the other devices. The result shows that reducing exergy loss of the capillary influenced by the ambient temperature is the key for improving working efficiency of an air-conditioning system when influence of the ambient temperature is considered. The higher ambient temperature causes the larger pressure drop of capillary and more exergy loss.
Numerical Analysis of Helicopter Rotor Hovering in Close Proximity to the Ground with a Wall
Itoga, Noriaki; Iboshi, Naohiro; Horimoto, Mitsumasa; Saito, Shigeru; Tanabe, Yasutada
In rescue operations and emergency medical services, helicopters are frequently required to operate near the ground with obstacles such as buildings and sidewalls of highway. In this paper, numerical analysis of helicopter rotor hovering in close proximity to the ground with an obstacle is done by solving unsteady 3D compressible Euler equations with an overlapped grid system. The obstacle is simulated by a wall vertically set up on the ground. The parameters for numerical analysis are the rotor height and distance from the rotor-hub-center to the wall. The effects of combinations of these parameters on the flowfields around the rotor, inflow distributions on the rotor disc and behaviors of blade flapping motion are discussed. It is also clarified the cause that the helicopter rotor hovering in close proximity to the ground with a wall does not have the enough ground effect depending on the combinations of these parameters.
Numerical analysis of a PCM thermal storage system with varying wall temperature
Halawa, E. [Sustainable Energy Centre, University of South Australia, Mawson Lakes, SA 5095 (Australia)]. E-mail: edward.halawa@unisa.edu.au; Bruno, F. [Sustainable Energy Centre, University of South Australia, Mawson Lakes, SA 5095 (Australia); Saman, W. [Sustainable Energy Centre, University of South Australia, Mawson Lakes, SA 5095 (Australia)
2005-09-15
Numerical analysis of melting and freezing of a PCM thermal storage unit (TSU) with varying wall temperature is presented. The TSU under analysis consists of several layers of thin slabs of a PCM subjected to convective boundary conditions where air flows between the slabs. The model employed takes into account the variations in wall temperature along the direction of air flow as well as the sensible heat. The paper discusses typical characteristics of the melting/freezing of PCM slabs in an air stream and presents some results of the numerical simulation in terms of air outlet temperatures and heat transfer rates during the whole periods of melting and freezing. Considerations in the design of the TSU are also given.
Numerical analysis on bearing capacity of middle pylon caisson foundation of Taizhou Bridge
Wang Jun; Shao Guojian; Hu Feng; Gu Lijun
2012-01-01
Because of the computation difficulty of the beating capacity of large underwater caisson foundation on thick overburden layer ground, the geotechnieal software FLAC3D was utilized in the 3D numerical analysis on the bearing capacity of middle pylon foundation. From the computational results, it is concluded that the caisson foundation has a good bearing capacity on thick overburden layer ground and the beating capacity can be improved assuming that the soil near the area of basal comer is reinforced.
Lazić Vukić N.
2014-01-01
Full Text Available The three-dimensional transient nonlinear thermal analysis of the hard facing process is performed by using the finite element method. The simulations were executed on the open source Salome platform using the open source finite element solver Code_Aster. The Gaussian double ellipsoid was selected in order to enable greater possibilities for the calculation of the moving heat source. The numerical results were compared with available experimental results.
Numerical analysis of added mass and damping of floating production,storage and offloading system
Ke Wang; Xi Zhang; Zhi-Qiang Zhang; Wang Xu
2012-01-01
An integral equation approach is utilized to investigate the added mass and damping of floating production,storage and offloading system (FPSO system).Finite water depth Green function and higher-order boundary element method are used to solve integral equation.Numerical results about added mass and damping are presented for odd and even mode motions of FPSO.The results show robust convergence in high frequency range and can be used in wave load analysis for FPSO designing and operation.
Klein, Max; Sharma, Rati; Bohrer, Chris H; Avelis, Cameron M; Roberts, Elijah
2017-01-15
Data-parallel programming techniques can dramatically decrease the time needed to analyze large datasets. While these methods have provided significant improvements for sequencing-based analyses, other areas of biological informatics have not yet adopted them. Here, we introduce Biospark, a new framework for performing data-parallel analysis on large numerical datasets. Biospark builds upon the open source Hadoop and Spark projects, bringing domain-specific features for biology.
Four generations versus left-right symmetry. A comparative numerical analysis
Heidsieck, Tillmann J.
2012-06-18
In this work, we present a comparative numerical analysis of the Standard Model (SM) with a sequential fourth generation (SM4) and the left-right symmetric Standard model (LRM). We focus on the constraints induced by flavour violating {Delta}F=2 processes in the K and B system while the results of studies of collider bounds and electroweak precision tests are taken into account as external inputs. In contrast to many previous studies of both models considered in this work, we do make not any ad-hoc assumptions on the structure of the relevant mixing matrices. Therefore, we employ powerful Monte Carlo methods in order to approximate the viable parameter space of the models. In preparation of our numerical analysis, we present all relevant formulae and review the different numerical methods used in this work. In order to better understand the patterns of new effects in {Delta}F=2 processes, we perform a fit including all relevant {Delta}F=2 constraints in the context of the Standard Model. The result of this fit is then used in a general discussion on new effects in {Delta}F=2 processes in the context of generic extensions of the Standard Model. Our numerical analysis of the SM4 and the LRM demonstrates that in both models the existing anomalies in {Delta}=2 processes can easily be resolved. We transparently show how the different observables are connected to each other by their dependence on combinations of mixing parameters. In our analysis of rare decays in the SM4, we establish patterns of flavour violation that could in principle be used to disprove this model on the basis of {Delta}F=1 processes alone. In the LRM, we discuss the importance of the contributions originating from the exchange of heavy, flavour changing, neutral Higgs bosons as well as the inability of the LRM to entirely solve the V{sub ub} problem.
Numerical analysis of rheological and tribological behavior influence on 16MnCr5 forging fibering
Gavrus, A.; Pintilie, D.; Nedelcu, R.
2016-10-01
The present research work is focus on the influence of the rheological constitutive equation and friction law formulation on 16MnCr5 forging fibering. Numerical analysis using FE Forge® and Abaqus code show the importance of the rheological softening terms on the metals fibers morphology and position coordinate. Calibration of friction law and sensitivity of softening parameters corresponding to a Hansel-Spittel rheological equation have been studied.
WEI Daoping; JIANG Zhong'ao; ZHAO Yucheng; JIAN Shuisheng
2000-01-01
Based on mode-coupled theory, a Bragg grating assisted mismatched fiber coupler is analyzed theoretically. At the same time, a detailed numerical analysis on transmission characteristics of the coupler is carried out when it considers the arcs of two fibers in the coupling region of the coupler or not, and the optimized design on the Bragg grating assisted mismatched fiber coupler for wavelength-division multiplexing/ demultiplexing is proposed.
Analysis of CO2 emission in traffic flow and numerical tests
Zhu, Wen-Xing
2013-10-01
We investigated the carbon dioxide emission rate in traffic flow analytically and numerically. The emission model was derived based on Bando’s optimal velocity model with a consideration of slope. Simulations were conducted to examine the relationship between the CO2 emission rate of vehicles and slope of road, traffic density, and road length. Analysis of the results shows that some original laws of CO2 emission in traffic flow with congestion were exhibited.
Mathematical and numerical analysis of a model for anti-angiogenic therapy in metastatic cancers
Benzekry, Sebastien
2010-01-01
We introduce and analyze a phenomenological model for anti-angiogenic therapy in the treatment of metastatic cancers. It is a structured transport equation with a nonlocal boundary condition describing the evolution of the density of metastasis that we analyze first at the continuous level. We present the numerical analysis of a lagrangian scheme based on the characteristics whose convergence establishes existence of solutions. Then we prove an error estimate and use the model to perform interesting simulations in view of clinical applications.
Gomes, Mateus das Neves; Seibt, Flávio Medeiros; Rocha, Luiz Alberto Oliveira; Santos, Elizaldo Domingues dos; Isoldi, Liércio André
2014-01-01
This work presents a 2D numerical study of an Oscillating Water Column (OWC) converter considering physical constraints in its outlet chimney to represent the turbine pressure drop. Two strategies were adopted. The first considers different dimensions for a physical constraint similar to an orifice plate, being the analysis performed in a laboratory scale. After that, other physical restriction with geometry similar to a rotor turbine was investigated in a real scale by means a dimensional va...
Numerical Tracking of Limit Points for Direct Parametric Analysis in Nonlinear Rotordynamics
Xie, Lihan; Baguet, Sébastien; Prabel, Benoit; Dufour, Régis
2016-01-01
International audience; A frequency-domain approach for direct parametric analysis of limit points of nonlinear dynamical systems is presented in this paper. Instead of computing responses curves for several values of a given system parameter, the direct tracking of limit points is performed. The whole numerical procedure is based on the Harmonic Balance Method and can be decomposed in three distinct steps. Firstly, a response curve is calculated by HBM combined with a continuation technique ...
CRSMP Potential Harbor Borrow Sites 2012
California Department of Resources — Harbor locations as identified originally in the California Shoreline Database compiled by Noble Consultants (Jon Moore) for California Department of Boating and...
Sohn, Jeong L.
1988-08-01
The purpose of the study is the evaluation of the numerical accuracy of FIDAP (Fluid Dynamics Analysis Package). Accordingly, four test problems in laminar and turbulent incompressible flows are selected and the computational results of these problems compared with other numerical solutions and/or experimental data. These problems include: (1) 2-D laminar flow inside a wall-driven cavity; (2) 2-D laminar flow over a backward-facing step; (3) 2-D turbulent flow over a backward-facing step; and (4) 2-D turbulent flow through a turn-around duct.
Coman, Paul Tiberiu; Veje, Christian
2013-01-01
Numerical model and analysis of peak temperature reduction in LiFePO4 battery packs using phase change materials......Numerical model and analysis of peak temperature reduction in LiFePO4 battery packs using phase change materials...
Coman, Paul Tiberiu; Veje, Christian
2013-01-01
Numerical model and analysis of peak temperature reduction in LiFePO4 battery packs using phase change materials......Numerical model and analysis of peak temperature reduction in LiFePO4 battery packs using phase change materials...
Numerical analysis of heat transfer in the exhaust gas flow in a diesel power generator
Brito, C. H. G.; Maia, C. B.; Sodré, J. R.
2016-09-01
This work presents a numerical study of heat transfer in the exhaust duct of a diesel power generator. The analysis was performed using two different approaches: the Finite Difference Method (FDM) and the Finite Volume Method (FVM), this last one by means of a commercial computer software, ANSYS CFX®. In FDM, the energy conservation equation was solved taking into account the estimated velocity profile for fully developed turbulent flow inside a tube and literature correlations for heat transfer. In FVM, the mass conservation, momentum, energy and transport equations were solved for turbulent quantities by the K-ω SST model. In both methods, variable properties were considered for the exhaust gas composed by six species: CO2, H2O, H2, O2, CO and N2. The entry conditions for the numerical simulations were given by experimental data available. The results were evaluated for the engine operating under loads of 0, 10, 20, and 37.5 kW. Test mesh and convergence were performed to determine the numerical error and uncertainty of the simulations. The results showed a trend of increasing temperature gradient with load increase. The general behaviour of the velocity and temperature profiles obtained by the numerical models were similar, with some divergence arising due to the assumptions made for the resolution of the models.
Numerical Analysis of Flow Phenomena in a Residual Heat Removal Pump
Jianping Yuan
2015-02-01
Full Text Available The hydraulic performances as well as the cavitation phenomena in a scaled residual heat removal pump were investigated by experimental and numerical methods, respectively. In particular, a 3D numerical model of cavitation was adopted to simulate the internal cavitating flow through the model pump. The hydraulic performances of the model pump predicted by numerical simulations were in good agreement with the corresponding experimental data. The main generation and evolution of attached cavitation throughout the blade channels at different cavitating conditions have been investigated using the vapor fraction ISO surface and in-plane velocity vectors. Results show that the low static pressure at the impeller inlet is the main reason for leading edge cavitation by correlation analysis of static pressure on the midspan of impeller. Cavitation proved to occur over a wide range of flow rates, producing a characteristic creeping shape of the head-drop curve and developing in the form of nonaxisymmetric cavities at design flow rate. Moreover, the occurrence of these cavities, attached to the suction surface of blades, was found to depend on the NPSHA value. Numerical and experimental results in this paper can provide better understanding of the origin of leading edge cavitation in residual heat removal pumps.
Asch, M.
1990-01-01
The author studies analytically and numerically a transport equation arising from acoustic wave propagation due to a point source in a randomly layered half space. Random material properties whose fluctuations are not restricted in magnitude, but are on a specific length scale are included in the acoustic equations. Analysis of the resulting stochastic differential equations by asymptotic methods lead to the derivation of a transport equation which describes the moments of the reflected pressure field. This equation is an infinite system of linear hyperbolic partial differential equations. A probabilistic interpretation of the transport equation by random walks leads to an existence and uniqueness proof. This interpretation is also the basis of numerical simulations by a Monte Carlo method for a plane wave problem. This is not an efficient numerical method, but provides insight into the mechanism of multiple scattering in the limit studied here. Finite difference methods must be used in the point source case. Due to the singular nature of the initial conditions he prefers to desingularize the system by substituting a progressing wave expansion. This desingularization is a prerequisite for solving an inverse problem. The regularized equations are then integrated and discretized using simple numerical methods. The resulting problem is extremely large (four dimensions plus time) and sophisticated vectorization and parallelization techniques must be applied in order to solve it efficiently. The results obtained are in good agreement with known explicit solutions for statistically homogeneous media.
Numerical analysis of non-stationary free surface flow in a Pelton bucket
Hana, Morten
1999-07-01
Computation and analysis of flow in Pelton buckets have been carried out. First a graphical method is investigated and partially improved. In order to decide whether to improve the method further or disregard it in favour of commercial computational fluid dynamics (CFD) codes, a study on numerical methods for free surface flow was carried out. This part of this work concentrates on the theoretical background for different numerical methods, and describes some practical considerations. Although small programs were created based on the literature survey, but only one reported herein, it was soon found that commonly available numerical codes were favourable in use. A code, RIPPLE, was acquired to study the Volume of Fluid (VOF) method in detail. The commercial codes used were Flow-3D and CFX-4. These programs were used in three different cases. First, a simplified 2-dimensional case was verified experimentally. Next, a 3-dimensional fixed jet calculation was carried out. Finally, numerical calculations with relative motion between the jet and buckets were carried out with CFX-4. The conclusion is that commercial CFD codes can replace the graphical method. But careful implementation is needed in order to resolve the special features of Pelton turbines, which are the free surface, the complex geometry and the relative motion between the jet and the bucket.
Prey capture by harbor porpoises
Miller, Lee
2008-01-01
their ultrasonic clicks as biosonar for orientation and detection of prey (mostly smaller pelagic and bottom dwelling fish), and for communication. For studying wild animals, hydrophone arrays [Villadsgaard et al. J.Exp.Biol. 210 (2007)] and acoustic (time/depth) tags [Akamatsu et al. Deep Sea Research II 54...... (2007)] have been used. For studying captive animals, arrays and video techniques [Verfuss et al. J.Exp.Biol. 208 (2005)] as well as miniature acoustic-behavioral tags [Deruiter et al. JASA 123 (2008)] have been used. While searching for prey, harbor porpoises use clicks at long intervals (~50 ms......) that progressively decrease when closing on an object. After detecting the prey, the click interval stabilizes and then becomes progressively shorter while approaching the prey. The sequence ends in a terminal, high repetition rate buzz (~500 clicks/s) just before capturing the prey (a video will be shown...
Numerical analysis of stress distribution in embedded highly birefringent PANDA fibers
Lesiak, Piotr; Woliński, Tomasz
2015-09-01
The paper presents numerical analysis compared with experimental data of influence of polymerization shrinkage on highly birefringent (HB) PANDA optical fibers embedded in a composite material. Since polymerization is a chemical process consisting in combining single molecules in a macromolecular compound [1], principal directions of the polymerization shrinkage depend on a number of the composite layers associated with this process. In this paper a detailed analysis of the piezo-optic effects occurring in HB optical fibers before and after the lamination process answers the question to what extent a degree of the material degradation can be properly estimated.
Impact of Entropy Generation on Stagnation-Point Flow of Sutterby Nanofluid: A Numerical Analysis
Azhar, Ehtsham; Iqbal, Z.; Maraj, E. N.
2016-09-01
The present article dicusses the computational analysis of entropy generation for the stagnation-point flow of Sutterby nanofluid over a linear stretching plate. The Sutterby fluid is chosen to study the effect for three major classes of non-Newtonian fluids, i.e. pseudoplastic, Newtonian, and dilatant. The effects of pertinent physical parameters are examined under the approximation of boundary layer. The system of coupled nonlinear partial differential equations is simplified by incorporating suitable similarity transformation into a system of non-linear-coupled ordinary differential equations. Entropy generation analysis is conducted numerically, and the results are displayed through graphs and tables. Significant findings are listed in the closing remarks.
无
2005-01-01
Finite and infinite coupled element method was used to analyze the strength and deformation in layered soil foundation which was under the rectangular shallow footing subjected to vertical loads. In the numerical analysis, the footing was assumed to be elastic; the soil was assumed to be elastoplastic and the Drucker-Prager constitutive model was applied to describe its mechanic behavior. Corresponding program was employed to compute six kinds of layered soil foundations constituted by different soil layers. The conclusions which are useful in the theory and practice were made according to the analysis of the computation results.
Numerical Second Law Analysis of a Refrigeration Phase-Change Storage
Jean-Pierre Bédécarrats
1999-09-01
Full Text Available
Second law analysis techniques, based on the calculation of entropy generation, are applied to the design and operation of an industrial refrigeration phase-change storage. The studied process consists in the use of encapsulated phase-change materials (PCM. A detailed analysis of the system permitted the development of a simulation program. So, the calculation of entropy generation has been made in a numerical way. The results are only presented for the discharge mode corresponding to the melting of the PCM.
Hermann BRUNNER
2009-01-01
The aims of this paper are (i) to present a survey of recent advances in the analysis of superconvergence of collocation solutions for linear Volterra-type functional integral and integro-differential equations with delay functions θ(t) vanishing at the initial point of the interval of integration (with θ(t) = qt (0 ＜ q ＜ 1,t ≥0) being an important special case),and (ii) to point,by means of a list of open problems,to areas in the numerical analysis of such Volterra functional equations where more research needs to be carried out.
Finite strip method combined with other numerical methods for the analysis of plates
Cheung, M. S.; Li, Wenchang
1992-09-01
Finite plate strips are combined with finite elements or boundary elements in the analysis of rectangular plates with some minor irregularities such as openings, skew edges, etc. The plate is divided into regular and irregular regions. The regular region is analyzed by the finite strip method while the irregular one is analyzed by the finite element or boundary element method. A special transition element and strip are developed in order to connect the both regions. Numerical examples will show the accuracy and efficiency of this combined analysis.
Experimental and Numerical Analysis of Screw Fixation in Anterior Cruciate Ligament Reconstruction
Chizari, Mahmoud; Wang, Bin; Snow, Martyn; Barrett, Mel
2008-09-01
This paper reports the results of an experimental and finite element analysis of tibial screw fixation in anterior cruciate ligament (ACL) reconstruction. The mechanical properties of the bone and tendon graft are obtained from experiments using porcine bone and bovine tendon. The results of the numerical study are compared with those from mechanical testing. Analysis shows that the model may be used to establish the optimum placement of the tunnel in anterior cruciate ligament reconstruction by predicting mechanical parameters such as stress, strain and displacement at regions in the tunnel wall.
2015-05-01
lwd. The authorized channel depth is -30 ft lwd at the entrance and -28 ft lwd in the Harbor. Original construction of Burns Harbor was completed in...and Burns Harbor North Breakwater, Indiana C oa st al a n d H yd ra u lic s La b or at or y Glenn B. Myrick, Jeffrey A. Melby, and...Breakwater, Ohio, and Burns Harbor North Breakwater, Indiana Glenn B. Myrick, Jeffrey A. Melby, and Elizabeth C. Burg Coastal and Hydraulics
MI-Sim: A MATLAB package for the numerical analysis of microbial ecological interactions.
Wade, Matthew J; Oakley, Jordan; Harbisher, Sophie; Parker, Nicholas G; Dolfing, Jan
2017-01-01
Food-webs and other classes of ecological network motifs, are a means of describing feeding relationships between consumers and producers in an ecosystem. They have application across scales where they differ only in the underlying characteristics of the organisms and substrates describing the system. Mathematical modelling, using mechanistic approaches to describe the dynamic behaviour and properties of the system through sets of ordinary differential equations, has been used extensively in ecology. Models allow simulation of the dynamics of the various motifs and their numerical analysis provides a greater understanding of the interplay between the system components and their intrinsic properties. We have developed the MI-Sim software for use with MATLAB to allow a rigorous and rapid numerical analysis of several common ecological motifs. MI-Sim contains a series of the most commonly used motifs such as cooperation, competition and predation. It does not require detailed knowledge of mathematical analytical techniques and is offered as a single graphical user interface containing all input and output options. The tools available in the current version of MI-Sim include model simulation, steady-state existence and stability analysis, and basin of attraction analysis. The software includes seven ecological interaction motifs and seven growth function models. Unlike other system analysis tools, MI-Sim is designed as a simple and user-friendly tool specific to ecological population type models, allowing for rapid assessment of their dynamical and behavioural properties.
33 CFR 100.109 - Winter Harbor Lobster Boat Race, Winter Harbor, ME.
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Winter Harbor Lobster Boat Race, Winter Harbor, ME. 100.109 Section 100.109 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF... Lobster Boat Race, Winter Harbor, ME. (a) Regulated area. The regulated area includes all waters of...
2010-12-16
... Orleans Harbor, Inner Harbor Navigation Canal, New Orleans, Orleans Parish, LA AGENCY: Coast Guard, DHS... Seeber/Claiborne Avenue) ] vertical lift bridge across the Inner Harbor Navigational Canal, mile 0.9, (Gulf Intracoastal Waterway mile 6.7 East of Harvey Lock), at New Orleans, Orleans Parish,...
2011-02-15
... Orleans Harbor, Inner Harbor Navigation Canal, New Orleans, Orleans Parish, LA AGENCY: Coast Guard, DHS... Seeber/Claiborne Avenue) vertical lift bridge across the Inner Harbor Navigational Canal, mile 0.9, (Gulf Intracoastal Waterway mile 6.7 East of Harvey Lock), at New Orleans, Orleans Parish, Louisiana. This...
Stress analysis and damage evaluation of flawed composite laminates by hybrid-numerical methods
Yang, Yii-Ching
1992-01-01
Structural components in flight vehicles is often inherited flaws, such as microcracks, voids, holes, and delamination. These defects will degrade structures the same as that due to damages in service, such as impact, corrosion, and erosion. It is very important to know how a structural component can be useful and survive after these flaws and damages. To understand the behavior and limitation of these structural components researchers usually do experimental tests or theoretical analyses on structures with simulated flaws. However, neither approach has been completely successful. As Durelli states that 'Seldom does one method give a complete solution, with the most efficiency'. Examples of this principle is seen in photomechanics which additional strain-gage testing can only average stresses at locations of high concentration. On the other hand, theoretical analyses including numerical analyses are implemented with simplified assumptions which may not reflect actual boundary conditions. Hybrid-Numerical methods which combine photomechanics and numerical analysis have been used to correct this inefficiency since 1950's. But its application is limited until 1970's when modern computer codes became available. In recent years, researchers have enhanced the data obtained from photoelasticity, laser speckle, holography and moire' interferometry for input of finite element analysis on metals. Nevertheless, there is only few of literature being done on composite laminates. Therefore, this research is dedicated to this highly anisotropic material.
NUMERICAL ANALYSIS OF THERMAL STRATIFICATION IN THE UPPER PLENUM OF THE MONJU FAST REACTOR
SEOK-KI CHOI
2013-04-01
Full Text Available A numerical analysis of thermal stratification in the upper plenum of the MONJU fast breeder reactor was performed. Calculations were performed for a 1/6 simplified model of the MONJU reactor using the commercial code, CFX-13. To better resolve the geometrically complex upper core structure of the MONJU reactor, the porous media approach was adopted for the simulation. First, a steady state solution was obtained and the transient solutions were then obtained for the turbine trip test conducted in December 1995. The time dependent inlet conditions for the mass flow rate and temperature were provided by JAEA. Good agreement with the experimental data was observed for steady state solution. The numerical solution of the transient analysis shows the formation of thermal stratification within the upper plenum of the reactor vessel during the turbine trip test. The temporal variations of temperature were predicted accurately by the present method in the initial rapid coastdown period (∼300 seconds. However, transient numerical solutions show a faster thermal mixing than that observed in the experiment after the initial coastdown period. A nearly homogenization of the temperature field in the upper plenum is predicted after about 900 seconds, which is a much shorter-term thermal stratification than the experimental data indicates. This discrepancy may be due to the shortcoming of the turbulence models available in the CFX-13 code for a natural convection flow with thermal stratification.
Takeda, Tetsuaki, E-mail: ttakeda@yamanashi.ac.jp; Hatori, Hirofumi; Funatani, Shumpei
2016-09-15
This study investigated a control method for natural circulation of air by helium gas injection. A depressurization accident is a design-basis accident of a very high temperature reactor. When a primary pipe rupture accident occurs, air is expected to enter the reactor pressure vessel from the breach. Thus, in-core graphite structures are oxidized. In order to predict and analyze the phenomena of air ingress during a depressurization accident, numerical analysis was carried out using a one-dimensional (1D) analysis code and three-dimensional computational fluid dynamics (3D CFD). An experiment was carried out regarding natural circulation using a circular pipe consisting of a reverse U-shaped channel. The channel consisted of two vertical heated and cooled pipes. The temperature difference between the vertical pipes was maintained at 40–80 K, and a small amount of helium gas was injected into the channel. The injected volume of helium was about 3.1–12.5% of the total channel volume. After injecting helium gas, each component gas moved through molecular diffusion and very weak natural circulation. After approximately 1180 s, ordinary natural circulation of air was suddenly produced. The numerical results of the 3D CFD code were in good agreement with the experimental results. The numerical results also showed that the natural circulation of air can be controlled by helium gas injection.
Cohesive Zone Model Based Numerical Analysis of Steel-Concrete Composite Structure Push-Out Tests
J. P. Lin
2014-01-01
Full Text Available Push-out tests were widely used to determine the shear bearing capacity and shear stiffness of shear connectors in steel-concrete composite structures. The finite element method was one efficient alternative to push-out testing. This paper focused on a simulation analysis of the interface between concrete slabs and steel girder flanges as well as the interface of the shear connectors and the surrounding concrete. A cohesive zone model was used to simulate the tangential sliding and normal separation of the interfaces. Then, a zero-thickness cohesive element was implemented via the user-defined element subroutine UEL in the software ABAQUS, and a multiple broken line mode was used to define the constitutive relations of the cohesive zone. A three-dimensional numerical analysis model was established for push-out testing to analyze the load-displacement curves of the push-out test process, interface relative displacement, and interface stress distribution. This method was found to accurately calculate the shear capacity and shear stiffness of shear connectors. The numerical results showed that the multiple broken lines mode cohesive zone model could describe the nonlinear mechanical behavior of the interface between steel and concrete and that a discontinuous deformation numerical simulation could be implemented.
Numerical analysis of thermal impact on hydro-mechanical properties of clay
Xuerui Wang
2014-10-01
Full Text Available As is known, high-level radioactive waste (HLW is commonly heat-emitting. Heat output from HLW will dissipate through the surrounding rocks and induce complex thermo-hydro-mechanical-chemical (THMC processes. In highly consolidated clayey rocks, thermal effects are particularly significant because of their very low permeability and water-saturated state. Thermal impact on the integrity of the geological barriers is of most importance with regard to the long-term safety of repositories. This study focuses on numerical analysis of thermal effects on hydro-mechanical properties of clayey rock using a coupled thermo-mechanical multiphase flow (TH2M model which is implemented in the finite element programme OpenGeoSys (OGS. The material properties of the numerical model are characterised by a transversal isotropic elastic model based on Hooke's law, a non-isothermal multiphase flow model based on van Genuchten function and Darcy's law, and a transversal isotropic heat transport model based on Fourier's law. In the numerical approaches, special attention has been paid to the thermal expansion of three different phases: gas, fluid and solid, which could induce changes in pore pressure and porosity. Furthermore, the strong swelling and shrinkage behaviours of clayey material are also considered in the present model. The model has been applied to simulate a laboratory heating experiment on claystone. The numerical model gives a satisfactory representation of the observed material behaviour in the laboratory experiment. The comparison of the calculated results with the laboratory findings verifies that the simulation with the present numerical model could provide a deeper understanding of the observed effects.
Numerical analysis of thermal impact on hydro-mechanical properties of clay
Xuerui Wang; Hua Shao; Jürgen Hesser; Chunliang Zhang; Wenqing Wang; Olaf Kolditz
2014-01-01
As is known, high-level radioactive waste (HLW) is commonly heat-emitting. Heat output from HLW will dissipate through the surrounding rocks and induce complex thermo-hydro-mechanical-chemical (THMC) processes. In highly consolidated clayey rocks, thermal effects are particularly significant because of their very low permeability and water-saturated state. Thermal impact on the integrity of the geological barriers is of most importance with regard to the long-term safety of repositories. This study focuses on numerical analysis of thermal effects on hydro-mechanical properties of clayey rock using a coupled thermo-mechanical multiphase flow (TH2M) model which is implemented in the finite element programme OpenGeoSys (OGS). The material properties of the numerical model are characterised by a transversal isotropic elastic model based on Hooke’s law, a non-isothermal multiphase flow model based on van Genuchten function and Darcy’s law, and a transversal isotropic heat transport model based on Fourier’s law. In the numerical approaches, special attention has been paid to the thermal expansion of three different phases: gas, fluid and solid, which could induce changes in pore pressure and porosity. Furthermore, the strong swelling and shrinkage behaviours of clayey material are also considered in the present model. The model has been applied to simulate a laboratory heating experiment on claystone. The numerical model gives a satisfactory representation of the observed material behaviour in the laboratory experiment. The comparison of the calculated results with the laboratory findings verifies that the simulation with the present numerical model could provide a deeper understanding of the observed effects.
NUMERICAL AND EXPERIMENTAL ANALYSIS OF UNSTEADY WORK OF U-SHAPE BOREHOLE HEAT EXCHANGER
S. A. Filatau
2014-01-01
Full Text Available Unsteady numerical model of borehole heat exchanger heat regime was developed. General numerical modeling results are borehole heat flux, heat carrier inlet temperature and average soil temperature distribution. Proposed model is based on solution of heat conduction equation in transient plane axially symmetric formulation with boundary conditions for borehole heat exchanger and undisturbed soil domain. Solution method is finite difference method. Numerical model is verified with comparisons numerical results and experimental data from developed laboratory installation for simulation unsteady heat regime of horizontal positioned U-shape ground heat exchanger in sand medium.Cooling of water is organized in ground exchanger in experiment. Experiment includes two steps. Thermal properties of sand is determined at the first stage. Thermal conductivity of sand is determined by stationary plate method, thermal diffusivity is determined by regular regime method using cylindrical calorimeter. Determined properties are used further in processing of experimental results at second step for analysis of transient work of ground heat exchanger. Results of four experiments are analyzed with different duration and time behavior of mass flow and heat carrier temperature. Divergences of experimental and simulated results for temperature of heat carrier changes in the range 0,5–1,8 %, for sand temperature in the range 1,0–2,3 %, for heat flux in the range 3,6–5,4 %. Experimental results can be used for validation of other simulation methods of ground heat exchangers. Presented numerical model can be used for analyzing of heat supply systems with heat pumps.
POLLUTION ASSESSMENT IN DREDGING SEDIMENT FROM HARBOR AREAS OF THE CIENFUEGOS BAY (CUBA
Anabell Pulido Caraballé
2016-04-01
Full Text Available The characterization of the dredging sediments is essential for environmental license, control and planning in dredging harbors. Sediment pollution was study in two harbor areas of the Cienfuegos Bay. Dredging sediments from “Camilo Cienfuegos” Refinery port and from area IX of Cienfuegos harbor were characterized. In order to evaluate dredging sediment quality, an analysis of water content, grain size, organic matter and trace metals was done. The results show that the trace elements in the sediments are at natural levels. Due to the absent of Cuban rules for these topics, international criteria for sampling, analysis and sediment quality evaluation were used in the study. Results show that these levels can be considered as typical for harbor areas in which authorization for dredging activities in docks and navigation channel should be granted. The results and methodologies will be applied in others Cuban harbors and navigation channel during the environmental license of dredging sediments.
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.
Numerical analysis of the beam position monitor pickup for the Iranian light source facility
Shafiee, M.; Feghhi, S. A. H.; Rahighi, J.
2017-03-01
In this paper, we describe the design of a button type Beam Position Monitor (BPM) for the low emittance storage ring of the Iranian Light Source Facility (ILSF). First, we calculate sensitivities, induced power and intrinsic resolution based on solving Laplace equation numerically by finite element method (FEM), in order to find the potential at each point of BPM's electrode surface. After the optimization of the designed BPM, trapped high order modes (HOM), wakefield and thermal loss effects are calculated. Finally, after fabrication of BPM, it is experimentally tested by using a test-stand. The results depict that the designed BPM has a linear response in the area of 2×4 mm2 inside the beam pipe and the sensitivity of 0.080 and 0.087 mm-1 in horizontal and vertical directions. Experimental results also depict that they are in a good agreement with numerical analysis.
Numerical Analysis for Optimal Design of Fin and Tube Type Adsorber
Kariya, Keishi; Kuwahara, Ken; Shigeru, Koyama
Adsorption cooling systems driven by low temperature waste heat (below 100°C) or renewable energy sources have gained considerable attention as one of the solutions for both energy and environment related problems. In this study, a two dimensional numerical analysis is carried out to evaluate the adsorption characteristics and to determine the performance of a fin and tube type adsorber/desorber heat exchanger; activated carbon fiber (ACF) of type A-20, which has relatively higher surface area, and ethanol are used as adsorbent/refrigerant pair. The effects of heat exchanger design configurations such as fin height, fin thickness, fin pitch, tube diameter and apparent density of ACF bed on the performance are examined numerically. The simulation results show that the cooling capacity can be optimized in the condition of fin height 15mm and fin pitch 5.5mm when other parameters are fixed.
A 3-D model of superfluid helium suitable for numerical analysis
Darve, C; Van Sciver, S W
2009-01-01
The two-fluid description is a very successful phenomenological representation of the properties of Helium II. A 3-D model suitable for numerical analysis based on the Landau-Khalatnikov description of Helium II is proposed. In this paper we introduce a system of partial differential equations that is both complete and consistent as well as practical, to be used for a 3-D solution of the flow of Helium II. The development of a 3-D numerical model for Helium II is motivated by the need to validate experimental results obtained by observing the normal component velocity distribution in a Helium II thermal counter-flow using the Particle Image Velocimetry (PIV) technique.
Hu Ding; Li-Qun Chen
2011-01-01
Steady-state periodical response is investigated for an axially moving viscoelastic beam with hybrid supports via approximate analysis with numerical confirmation.It is assumed that the excitation is spatially uniform and temporally harmonic. The transverse motion of axially moving beams is governed by a nonlinear partial-differential equation and a nonlinear integro-partial-differential equation. The material time derivative is used in the viscoelastic constitutive relation. The method of multiple scales is applied to the governing equations to investigate primary resonances under general boundary conditions. It is demonstrated that the mode uninvolved in the resonance has no effect on the steady-state response. Numerical examples are presented to demonstrate the effects of the boundary constraint stiffness on the amplitude and the stability of the steady-state response. The results derived for two governing equations are qualitatively the same, but quantitatively different. The differential quadrature schemes are developed to verify those results via the method of multiple scales.
Continuous limit of a crowd motion and herding model: Analysis and numerical simulations
Pietschmann, Jan-Frederik
2011-11-01
In this paper we study the continuum limit of a cellular automaton model used for simulating human crowds with herding behaviour. We derive a system of non-linear partial differential equations resembling the Keller-Segel model for chemotaxis, however with a non-monotone interaction. The latter has interesting consequences on the behaviour of the model\\'s solutions, which we highlight in its analysis. In particular we study the possibility of stationary states, the formation of clusters and explore their connection to congestion. We also introduce an efficient numerical simulation approach based on an appropriate hybrid discontinuous Galerkin method, which in particular allows flexible treatment of complicated geometries. Extensive numerical studies also provide a better understanding of the strengths and shortcomings of the herding model, in particular we examine trapping effects of crowds behind nonconvex obstacles. © American Institute of Mathematical Sciences.
L. A. F. de Souza
Full Text Available The experimental results of testing structures or structural parts are limited and, sometimes, difficult to interpret. Thus, the development of mathematical-numerical models is needed to complement the experimental analysis and allow the generalization of results for different structures and types of loading. This article makes two computational studies of reinforced concrete structures problems found in the literature, using the Finite Element Method. In these analyses, the concrete is simulated with the damage classical model proposed by Mazars and the steel by a bilinear elastoplastic constitutive model. Numerical results show the validity of the application of constitutive models which consider the coupling of theories with the technique of finite element discretization in the simulation of linear and two-dimensional reinforced concrete structures.
Numerical analysis of phase decomposition in A-B binary alloys using Cahn-Hilliard equations
Susana Lezama-Alvarez
2013-01-01
Full Text Available The analysis of phase decomposition was carried out using the nonlinear and linear Cahn-Hilliard equations in a hypothetical A-B alloy system with a miscibility gap. These equations were solved by the explicit finite difference method assuming a regular solution model. The supersaturated solid solution and decomposed phases were considered to have an fcc structure. Different aging temperatures and thermodynamic interaction parameters ΩA-B were used to simulate different alloy systems. The numerical simulation results showed that the growth kinetics of phase decomposition in the alloy with 30at.% A was slower than that of 50 at.% A. Additionally, the start time and modulation wavelength of phase decomposition are strongly affected by the thermodynamic interaction parameter ΩA-B value. The numerical simulation results showed that the growth kinetics of phase decomposition with the linear equation is slower than that with the nonlinear one.
Numerical Analysis of Mold Deformation Including Plastic Melt Flow During Injection Molding
Jung, Joon Tae; Lee, Bong-Kee [Chonnam National University, Gwangju (Korea, Republic of)
2014-07-15
In the present study, a numerical analysis of an injection molding process was conducted for predicting the mold deformation considering non-Newtonian flow, heat transfer, and structural behavior. The accurate prediction of mold deformation during the filling stage is important to successfully design and manufacture a precision injection mold. While the local mold deformation can be caused by various factors, a pressure induced by the polymer melt is considered to be one of the most significant ones. In this regard, the numerical simulation considering both the melt filling and the mold deformation was carried out. A mold core for a 2D axisymmetric center-gated disk was used for the demonstration of the present study. The flow behavior inside the mold cavity and temperature distribution were analyzed along with the core displacement. Also, a Taguchi method was employed to investigate the influence of the relevant parameters including flow velocity, mold core temperature, and melt temperature.
Numerical Analysis on Failure Modes and Mechanisms of Mine Pillars under Shear Loading
Tianhui Ma
2016-01-01
Full Text Available Severe damage occurs frequently in mine pillars subjected to shear stresses. The empirical design charts or formulas for mine pillars are not applicable to orebodies under shear. In this paper, the failure process of pillars under shear stresses was investigated by numerical simulations using the rock failure process analysis (RFPA 2D software. The numerical simulation results indicate that the strength of mine pillars and the corresponding failure mode vary with different width-to-height ratios and dip angles. With increasing dip angle, stress concentration first occurs at the intersection between the pillar and the roof, leading to formation of microcracks. Damage gradually develops from the surface to the core of the pillar. The damage process is tracked with acoustic emission monitoring. The study in this paper can provide an effective means for understanding the failure mechanism, planning, and design of mine pillars.
Analysis of the flamelet concept in the numerical simulation of laminar partially premixed flames
Consul, R.; Oliva, A.; Perez-Segarra, C.D.; Carbonell, D. [Centre Tecnologic de Transferencia de Calor (CTTC), Universitat Politecnica de Catalunya (UPC), Colom 11, E-08222, Terrassa, Barcelona (Spain); de Goey, L.P.H. [Eindhoven University of Technology, Department of Mechanical Engineering, P.O. Box 513, 5600 MB Eindhoven (Netherlands)
2008-04-15
The aim of this work is to analyze the application of flamelet models based on the mixture fraction variable and its dissipation rate to the numerical simulation of partially premixed flames. Although the main application of these models is the computation of turbulent flames, this work focuses on the performance of flamelet concept in laminar flame simulations removing, in this way, turbulence closure interactions. A well-known coflow methane/air laminar flame is selected. Five levels of premixing are taken into account from an equivalence ratio {phi}={infinity} (nonpremixed) to {phi}=2.464. Results obtained using the flamelet approaches are compared to data obtained from the detailed solution of the complete transport equations using primitive variables. Numerical simulations of a counterflow flame are also presented to support the discussion of the results. Special emphasis is given to the analysis of the scalar dissipation rate modeling. (author)
RodrIguez-MartInez, R; Urriolagoitia-Calderon, G; Urriolagoitia-Sosa, G; Hernandez-Gomez, L H [Instituto Politecnico Nacional Seccion de Estudios de Posgrado e Investigacion (SEPI), Escuela Superior de IngenierIa Mecanica y Electrica (ESIME), Edificio 5. 2do Piso, Unidad Profesional Adolfo Lopez Mateos ' Zacatenco' Col. Lindavista, C.P. 07738, Mexico, D.F. (Mexico); Merchan-Cruz, E A; RodrIguez-Canizo, R G; Sandoval-Pineda, J M, E-mail: rrodriguezm@ipn.m, E-mail: urrio332@hotmail.co, E-mail: guiurri@hotmail.co, E-mail: luishector56@hotmail.co, E-mail: eamerchan@gmail.co, E-mail: ricname@hotmail.co, E-mail: jsandovalp@ipn.m [Instituto Politecnico Nacional Seccion de Estudios de Posgrado e Investigacion (SEPI), Escuela Superior de IngenierIa Mecanica y Electrica (ESIME). Unidad profesional, AZCAPOTZALCO, Av. de las Granjas No. 682, Col. Sta. Catarina Azcapotzalco, C.P. 02550, Mexico D.F. (Mexico)
2009-08-01
In this paper, the case of Single Edge Notch (SEN) specimens subject to opening/compressive loading was analyzed; The loads are applied in several ratios to evaluate the influence of the specimen geometry, and the Stress Intensity Factor (SIF) K{sub 1} values on the directional stability of crack propagation. The main purpose of this work is to evaluate the behaviour of the fracture propagation, when modifying the geometry of the SEN specimen and different relationships of load tension/compression are applied. Additionally, the precision of the numerical and experimental analysis is evaluated to determine its reliability when solving this type of problems. The specimens are subjected to biaxial opening/compression loading; both results (numerical and experimental) are compared in order to evaluate the condition of directional stability on crack propagation. Finally, an apparent transition point related to the length of specimens was identified, in which the behaviour of values of SIF changes for different loading ratios.
Myong, Hyong Kook; Kwon, Young Hoo [Dept. of Mechanical Engineering, Kookmin University, Seoul (Korea, Republic of)
2015-03-15
Fluid transport is a key issue in the development of microfluidic systems. Recently, Myong (2014) has proposed a new concept for droplet transport without external power sources and numerically validated the results for a hypothetical 2D, initially having a hemicylindrical droplet. In this paper, the movement of an actual water droplet, initially having a 3D hemispherical shape, on horizontal hydrophilic/hydrophobic surfaces is simulated using a commercial computational fluid dynamics (CFD) package, Fluent, with VOF (volume of fluid) method. The results are compared with the 2D analysis of Myong (2014), and the transport mechanism for the actual water droplet is examined based on the numerical results of the time evolution of the droplet shape, as well as the total kinetic, gravitational, surface free and pressure energies inside the droplet.
Cheng Caixia; Sun Fuchun; Zhou Xinquan; Niu Huiyong; Liang De
2011-01-01
Various physical parameters,including gas concentrations (O2,CO,CH4,and H2) and temperatures at different air velocities,were determined for full scale wood fires in the Chongqing Coal Research Institute fire test tunnel.Both experimental measurements and numerical simulations are discussed.The numerical analysis was performed with the computational fluid dynamics software package “FLUENT”.The results show that the experimental data agree with the simulation results.The results verify that Roberts'theory of burning is correct.They also prove that the air velocity is the key factor that determines the type of combustion.Also,it is shown that secondary disasters are unlikely for oxygen rich combustion with a limited fire load.
Numerical analysis of two pile caps with sockets embedded, subject the eccentric compression load
R. G. Delalibera
Full Text Available The structural behavior of pile caps with sockets embedded is influenced by interface of column-socket, which can be smooth or rough. With intent to analyze the behavior of two pile caps with embedded socket, considering the friction between the column and the socket, with eccentric normal load, the numerical simulations were carried out, using a program based on the Finite Element Methods (FEM. In the numerical analysis the non-linear behavior of materials was considered, also the friction between the column and the socket. It was considered perfect bond between the reinforcement and the concrete around. It was observed that the embedded length is preponderant factor in the structural behavior of the analyzed element.
Madaket Harbor, Nantucket, Massachusetts. Water Resources Improvement.
1977-07-01
beamc. Tnis material will be re-deposited,, viaj troio it 1-apfro1inr ox prior location. j, MADAKET HARBOR NANTUCKET, MASSACHUSETTS FEASIBILITY...re- colonization of approximately 395 acres by scallops and quahogs. Also, barring any future disruption of the harbor area, the continued use of
33 CFR 117.549 - Cambridge Harbor.
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Cambridge Harbor. 117.549 Section... DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Maryland § 117.549 Cambridge Harbor. The draw of the S342 bridge, mile 0.1 at Cambridge, shall open on signal from 6 a.m. to 8 p.m.; except that, from...
Numerical Well Test Analysis for Polymer Flooding considering the Non-Newtonian Behavior
Jia Zhichun
2015-01-01
Full Text Available Well test analysis for polymer flooding is different from traditional well test analysis because of the non-Newtonian properties of underground flow and other mechanisms involved in polymer flooding. Few of the present works have proposed a numerical approach of pressure transient analysis which fully considers the non-Newtonian effect of real polymer solution and interprets the polymer rheology from details of pressure transient response. In this study, a two-phase four-component fully implicit numerical model incorporating shear thinning effect for polymer flooding based on PEBI (Perpendicular Bisection grid is developed to study transient pressure responses in polymer flooding reservoirs. Parametric studies are conducted to quantify the effect of shear thinning and polymer concentration on the pressure transient response. Results show that shear thinning effect leads to obvious and characteristic nonsmoothness on pressure derivative curves, and the oscillation amplitude of the shear-thinning-induced nonsmoothness is related to the viscosity change decided by shear thinning effect and polymer concentration. Practical applications are carried out with shut-in data obtained in Daqing oil field, which validates our findings. The proposed method and the findings in this paper show significant importance for well test analysis for polymer flooding and the determination of the polymer in situ rheology.
Vibro-Acoustic Numerical Analysis for the Chain Cover of a Car Engine
Enrico Armentani
2017-06-01
Full Text Available In this work, a vibro-acoustic numerical and experimental analysis was carried out for the chain cover of a low powered four-cylinder four-stroke diesel engine, belonging to the FPT (FCA Power Train family called SDE (Small Diesel Engine. By applying a methodology used in the acoustic optimization of new FPT engine components, firstly a finite element model (FEM of the engine was defined, then a vibration analysis was performed for the whole engine (modal analysis, and finally a forced response analysis was developed for the only chain cover (separated from the overall engine. The boundary conditions applied to the chain cover were the accelerations experimentally measured by accelerometers located at the points of connection among chain cover, head cover, and crankcase. Subsequently, a boundary element (BE model of the only chain cover was realized to determine the chain cover noise emission, starting from the previously calculated structural vibrations. The numerical vibro-acoustic outcomes were compared with those experimentally observed, obtaining a good correlation. All the information thus obtained allowed the identification of those critical areas, in terms of noise generation, in which to undertake necessary improvements.
The Analysis and Design of Low Boom Configurations Using CFD and Numerical Optimization Techniques
Siclari, Michael J.
1999-01-01
The use of computational fluid dynamics (CFD) for the analysis of sonic booms generated by aircraft has been shown to increase the accuracy and reliability of predictions. CFD takes into account important three-dimensional and nonlinear effects that are generally neglected by modified linear theory (MLT) methods. Up to the present time, CFD methods have been primarily used for analysis or prediction. Some investigators have used CFD to impact the design of low boom configurations using trial and error methods. One investigator developed a hybrid design method using a combination of Modified Linear Theory (e.g. F-functions) and CFD to provide equivalent area due to lift driven by a numerical optimizer to redesign or modify an existing configuration to achieve a shaped sonic boom signature. A three-dimensional design methodology has not yet been developed that completely uses nonlinear methods or CFD. Constrained numerical optimization techniques have existed for some time. Many of these methods use gradients to search for the minimum of a specified objective function subject to a variety of design variable bounds, linear and nonlinear constraints. Gradient based design optimization methods require the determination of the objective function gradients with respect to each of the design variables. These optimization methods are efficient and work well if the gradients can be obtained analytically. If analytical gradients are not available, the objective gradients or derivatives with respect to the design variables must be obtained numerically. To obtain numerical gradients, say, for 10 design variables, might require anywhere from 10 to 20 objective function evaluations. Typically, 5-10 global iterations of the optimizer are required to minimize the objective function. In terms of using CFD as a design optimization tool, the numerical evaluation of gradients can require anywhere from 100 to 200 CFD computations per design for only 10 design variables. If one CFD
Hong, Dong Pyo; Kim, Ho Jong [School of Mechanical System Engineering, Chonbuk Nationa University, Jeonju (Korea, Republic of); Kim, Won Tae [School of Mechanical and Automotive Engineering, Kongju National University, Kongju (Korea, Republic of)
2013-08-15
With the modern machinery towards the direction of high-speed development, the thermal issues of mechanical transmission system and its components is increasingly important. Ball bearing is one of the main parts in rotating machinery system, and is a more easily damaged part. In this paper, bearing thermal fault detection is investigated in details Using infrared thermal imaging technology to the operation state of the ball bearing, a preliminary thermal analysis, and the use of numerical simulation technology by finite element method(FEM) under thermal conditions of the bearing temperature field analysis, initially identified through these two technical analysis, bearing a temperature distribution in the normal state and failure state. It also shows the reliability of the infrared thermal imaging technology with valuable suggestions for the future bearing fault detection.
Rheological numerical simulation for thermo-hydro-mechanical coupling analysis for rock mass
WANG Zhi-yin; XU Jie; LI Yun-peng; GUO Shu-tai; AI Chuan-zhi
2007-01-01
Under the environment of seepage field, stress field and temperature field interaction and influence, the three fields will not only produce coupling effect, but also have deformation with time due to the rheological behavior of rock mass. In the paper, based on the fundamental theories of rock mass coupling theory and rheological mechanics, the rheological model for fully coupled thermo-hydro-mechanical analysis for rock mass was set up, and the corresponding constitutive relationship, the conservation equation of mass and the conservation equation of energy were given, and the finite element formulas were derived for coupling analysis of rock mass. During establishing governing equations, rock mass was assumed approximately as macro-equivalent continuum medium. The obtained rheological numerical model for fully coupled thermo-hydro-mechanical analysis can be used for analyzing and predicting the long-term stability of underground caverns and slope engineering under the condition of thermo-hydro-mechanical coupling with rheological deformation.
Numerical continuation and bifurcation analysis in aircraft design: an industrial perspective.
Sharma, Sanjiv; Coetzee, Etienne B; Lowenberg, Mark H; Neild, Simon A; Krauskopf, Bernd
2015-09-28
Bifurcation analysis is a powerful method for studying the steady-state nonlinear dynamics of systems. Software tools exist for the numerical continuation of steady-state solutions as parameters of the system are varied. These tools make it possible to generate 'maps of solutions' in an efficient way that provide valuable insight into the overall dynamic behaviour of a system and potentially to influence the design process. While this approach has been employed in the military aircraft control community to understand the effectiveness of controllers, the use of bifurcation analysis in the wider aircraft industry is yet limited. This paper reports progress on how bifurcation analysis can play a role as part of the design process for passenger aircraft. © 2015 The Author(s).
Castaldo, R.; Tizzani, P.; Lollino, P.; Calò, F.; Ardizzone, F.; Lanari, R.; Guzzetti, F.; Manunta, M.
2015-11-01
The aim of this paper is to propose a methodology to perform inverse numerical modelling of slow landslides that combines the potentialities of both numerical approaches and well-known remote-sensing satellite techniques. In particular, through an optimization procedure based on a genetic algorithm, we minimize, with respect to a proper penalty function, the difference between the modelled displacement field and differential synthetic aperture radar interferometry (DInSAR) deformation time series. The proposed methodology allows us to automatically search for the physical parameters that characterize the landslide behaviour. To validate the presented approach, we focus our analysis on the slow Ivancich landslide (Assisi, central Italy). The kinematical evolution of the unstable slope is investigated via long-term DInSAR analysis, by exploiting about 20 years of ERS-1/2 and ENVISAT satellite acquisitions. The landslide is driven by the presence of a shear band, whose behaviour is simulated through a two-dimensional time-dependent finite element model, in two different physical scenarios, i.e. Newtonian viscous flow and a deviatoric creep model. Comparison between the model results and DInSAR measurements reveals that the deviatoric creep model is more suitable to describe the kinematical evolution of the landslide. This finding is also confirmed by comparing the model results with the available independent inclinometer measurements. Our analysis emphasizes that integration of different data, within inverse numerical models, allows deep investigation of the kinematical behaviour of slow active landslides and discrimination of the driving forces that govern their deformation processes.
Brunetti, J.; Massi, F.; Saulot, A.; Renouf, M.; D`Ambrogio, W.
2015-06-01
Mechanical systems present several contact surfaces between deformable bodies. The contact interface can be either static (joints) or in sliding (active interfaces). The sliding interfaces can have several roles and according to their application they can be developed either for maximizing the friction coefficient and the energy dissipation (e.g. brakes) or rather to allow the relative displacement at joints with a maximum efficiency. In both cases the coupling between system and local contact dynamics can bring to system dynamics instabilities (e.g. brake squeal or squeaking of hip prostheses). This results in unstable vibrations of the system, induced by the oscillation of the contact forces. In the literature, a large number of works deal with such kind of instabilities and are mainly focused on applied problems such as brake squeal noise. This paper shows a more general numerical analysis of a simple system constituted by two bodies in sliding contact: a rigid cylinder rotating inside a deformable one. The parametrical Complex Eigenvalue Analysis and the transient numerical simulations show how the friction forces can give rise to in-plane dynamic instabilities due to the interaction between two system modes, even for such a simple system characterized by one deformable body. Results from transient simulations highlight the key role of realistic values of the material damping to have convergence of the model and, consequently, reliable physical results. To this aim an experimental estimation of the material damping has been carried out. Moreover, the simplicity of the system allows for a deeper analysis of the contact instability and a balance of the energy flux among friction, system vibrations and damping. The numerical results have been validated by comparison with experimental ones, obtained by a specific test bench developed to reproduce and analyze the contact friction instabilities.
Terachi, Yusuke; Terao, Yutaka; Ohsaki, Hiroyuki; Sakurai, Yuki; Matsumura, Tomotake; Sugai, Hajime; Utsunomiya, Shin; Kataza, Hirokazu; Yamamoto, Ryo
2017-07-01
We have carried out numerical analysis of mechanical properties of a superconducting magnetic bearing (SMB). A contactless bearing operating at below 10 K with low rotational energy loss is an attractive feature to be used as a rotational mechanism of a polarization modulator for a cosmic microwave background experiment. In such application, a rotor diameter of about 400 mm forces us to employ a segmented magnet. As a result, there is inevitable spatial gap between the segments. In order to understand the path towards the design optimizations, 2D and 3D FEM analyses were carried out to examine fundamental characteristics of the SMBs for a polarization modulator. Two axial flux type SMBs were dealt with in the analysis: (a) the SMB with axially magnetized permanent magnets (PMs), and (b) the SMB with radially magnetized PMs and steel components for magnetic flux paths. Magnetic flux lines and density distributions, electromagnetic force characteristics, spring constants, etc. were compared among some variations of the SMBs. From the numerical analysis results, it is discussed what type, configuration and design of SMBs are more suitable for a polarization modulator.
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.
Performance analysis of a wave energy converter using numerical simulation technique
Mohammed; Asid; ZULLAH; Deepak; PRASAD; Mohammed; Rafiuddin; AHMED; Young-Ho; LEE
2010-01-01
A general purpose viscous flow solver Ansys CFX was used to study a Savonius type wave energy converter in a 3D numerical viscous wave tank.This paper presents the results of a computational fluid dynamics(CFD) analysis of the effect of blade configuration on the performance of two Savonius rotors for wave energy extraction.A piston-type wave generator was incorporated in the computational domain to generate the desired incident waves.A complete OWC system with a 3-bladed Savonius rotor was modeled in a three dimensional numerical wave tank and the hydrodynamic conversion efficiency was estimated.The flow over the rotors was assumed to be two-dimensional(2D),viscous,turbulent and unsteady.The CFX code was used with a solver of the coupled conservation equations of mass,momentum and energy,with an implicit time scheme and with the adoption of the hexahedral mesh and the moving mesh techniques in areas of moving surfaces.Turbulence was modeled with the k-e model.The results indicated that the developed models are suitable to analyze the water flows both in the chamber and in the turbine.For the turbine,the numerical results of pressure and torque were compared for the two cases.
Numerical Analysis of Effect of Water on Explosive Wave Propagation in Tunnels and Surrounding Rock
XIA Chang-jing; SONG Zhen-duo; TIAN Lu-lu; LIU Hong-bin; WANG Lu; WU Xiao-fang
2007-01-01
Based on the application of practical engineering, propagation processes of explosive waves in rock with water well and tunnel are simulated by ANSYS/LS-DYNA software. The evolution of damage in rock is presented. The effect of water on the damage of the concrete slab in a tunnel is compared with damage inflicted without water. The numerical simulation illustrates that water plays an important role in the evolution of damage of the concrete slab in a mine tunnel. In the presence of water in the rock the concrete slab is damaged more severely than without water in rock. The effect of water location in the rock is also considered. It is found that the concrete slab in the tunnel shows various degrees of damage as a function of the different locations of water. Attenuation laws of stress waves over time-space in rock with water are also obtained. Numerical results indicate that, under blast loading, there are three zones in the rock: a crushed zone nearby the explosive charge, a damaged zone and an elastic zone. The conclusions of numerical analysis may provide references for blasting designs and structure protection.
A Numerical Analysis Of Gaseous Flow in the Entrance Region of Micro-channels
Sampad Gobinda Das
2010-06-01
Full Text Available Fluid flow in micro-channels is rapidly emerging as a major area of research, due to its wide area of applications invarious forms in industries. Although substantial work has been carried out xperimentally, numerically as well as analytically on this area, still the reported results show wide variation from one another. In the present work an attempt has been made to analyze gaseous flow in two dimensional micro-channels by using a numerical scheme.The momentum equation has been converted into stream function vorticity form and a finite difference technique has been used. Both slip and no slip boundary conditions have been applied and nitrogen and helium have been considered as representative ideal gases. The numerical scheme has been validated and the results have shown theimportance of Knudsen number apart from Reynolds number, in the gaseous flow during its hydro dynamically developing stage. The present work has carried out a comparative study based on the code developed, between nitrogen and helium, one of them being a monatomic gas and the other diatomic. Also a non dimensional analysis has been presented.
Yang Ning; Wang Nan; Zhang Xin; Liu Wei
2016-01-01
The flutter characteristics of folding control fins with freeplay are investigated by numer-ical simulation and flutter wind tunnel tests. Based on the characteristics of the structures, fins with different freeplay angles are designed. For a 0? angle of attack, wind tunnel tests of these fins are conducted, and vibration is observed by accelerometers and a high-speed camera. By the expansion of the connected relationships, the governing equations of fit for the nonlinear aeroelastic analysis are established by the free-interface component mode synthesis method. Based on the results of the wind tunnel tests, the flutter characteristics of fins with different freeplay angles are analyzed. The results show that the vibration divergent speed is increased, and the divergent speed is higher than the flutter speed of the nominal linear system. The vibration divergent speed is increased along with an increase in the freeplay angle. The developed free-interface component mode synthesis method could be used to establish governing equations and to analyze the characteristics of nonlinear aeroe-lastic systems. The results of the numerical simulations and the wind tunnel tests indicate the same trends and critical velocities.
Analysis on the Foucault pendulum by De Alembert Principle and Numerical Simulation
Zheng, Zhiwu
2015-01-01
In this paper, we handle the problem of the motion of the Foucault pendulum. We explore a new method induced from the De Alembert Principle giving the motional equations without small-amplitude oscillation approximation. The result of the problem is illustrated by numerical analysis showing the non-linear features and then with a comparison with a common method, showing the merit of this new original method. The result also shows that the argument changes in near-harmonic mode and the swing plane changes in pulsing way.
Foundation, analysis, and numerical investigation of a variational network-based model for rubber
Gloria, Antoine; Le Tallec, Patrick; Vidrascu, Marina
2014-01-01
Since the pioneering work by Treloar, many models based on polymer chain statistics have been proposed to describe rubber elasticity. Recently, Alicandro, Cicalese, and the first author rigorously derived a continuum theory of rubber elasticity from a discrete model by variational convergence. The aim of this paper is twofold. First, we further physically motivate this model and complete the analysis by numerical simulations. Second, in order to compare this model to the literature, we present in a common language two other representative types of models, specify their underlying assumptions, check their mathematical properties, and compare them to Treloar's experiments.
Hofland, G.S.; Barton, C.C.
1990-10-01
The computer program FREQFIT is designed to perform regression and statistical chi-squared goodness of fit analysis on one-dimensional or two-dimensional data. The program features an interactive user dialogue, numerous help messages, an option for screen or line printer output, and the flexibility to use practically any commercially available graphics package to create plots of the program`s results. FREQFIT is written in Microsoft QuickBASIC, for IBM-PC compatible computers. A listing of the QuickBASIC source code for the FREQFIT program, a user manual, and sample input data, output, and plots are included. 6 refs., 1 fig.
Quasinormal modes and stability of the rotating acoustic black hole: numerical analysis
Cardoso, V; Yoshida, S; Cardoso, Vitor; Lemos, Jose' P. S.; Yoshida, Shijun
2004-01-01
The study of the quasinormal modes (QNMs) of the 2+1 dimensional rotating draining bathtub acoustic black hole, the closest analogue found so far to the Kerr black hole, is performed. Both the real and imaginary parts of the quasinormal (QN) frequencies as a function of the rotation parameter B are found through a full non-linear numerical analysis. Since there is no change in sign in the imaginary part of the frequency as B is increased we conclude that the 2+1 dimensional rotating draining bathtub acoustic black hole is stable against small perturbations.
Hockett, P; Lux, C; Baumert, T
2015-01-01
The feasibility of complete photoionization experiments, in which the full set of photoionization matrix elements are determined, using multiphoton ionization schemes with polarization-shaped pulses has recently been demonstrated [Hockett et. al., Phys. Rev. Lett. 112, 223001 (2014)]. Here we extend on our previous work to discuss further details of the numerics and analysis methodology utilised, and compare the results directly to new tomographic photoelectron measurements, which provide a more sensitive test of the validity of the results. In so doing we discuss in detail the physics of the photoionziation process, and suggest various avenues and prospects for this coherent multiplexing methodology.
Analysis of stimulated Brillouin scattering in multi-mode fiber by numerical solution
周涛; 陈军
2003-01-01
Stimulated Brillouin scattering in optical fibers is described by a theoretical model and numerical analysis. The results showed that, for an optical fiber pumped by a laser beam with ns-order-pulse width and kW-order peak-power, SBS reflectivity tends to saturate when the fiber length exceeds a limit, named "effective fiber length". Using small core-diameter and long enough fiber, the SBS reflectivity level could be raised but is limited by optical damage of the entrance surface of the fiber. Therefore, just a small dynamic range can be obtained.
Hofland, G.S.; Barton, C.C.
1990-10-01
The computer program FREQFIT is designed to perform regression and statistical chi-squared goodness of fit analysis on one-dimensional or two-dimensional data. The program features an interactive user dialogue, numerous help messages, an option for screen or line printer output, and the flexibility to use practically any commercially available graphics package to create plots of the program`s results. FREQFIT is written in Microsoft QuickBASIC, for IBM-PC compatible computers. A listing of the QuickBASIC source code for the FREQFIT program, a user manual, and sample input data, output, and plots are included. 6 refs., 1 fig.
Numerical analysis of the electromechanically coupled magnetic field in brushless DC motors
Jang, G. H.; Chang, J. H.
2001-05-01
This paper presents a numerical method to solve the electromechanically coupled equations in a brushless DC (BLDC) motor, i.e. Maxwell equation, voltage equation and Newton's equations by introducing the nonlinear finite element analysis and the time stepping method. It also investigates the coupling effect of the eccentric motion of a rotor on the characteristics of the magnetic force and the resulting motion of a BLDC motor by analyzing the free response and Fourier transform of the excitation force and the resulting displacement.
Numerical analysis of the electromechanically coupled magnetic field in brushless DC motors
Jang, G.H. E-mail: ghjang@email.hanyang.ac.kr; Chang, J.H
2001-05-01
This paper presents a numerical method to solve the electromechanically coupled equations in a brushless DC (BLDC) motor, i.e. Maxwell equation, voltage equation and Newton's equations by introducing the nonlinear finite element analysis and the time stepping method. It also investigates the coupling effect of the eccentric motion of a rotor on the characteristics of the magnetic force and the resulting motion of a BLDC motor by analyzing the free response and Fourier transform of the excitation force and the resulting displacement.
Numerical Analysis of the Mixing Zone for a Vertical Discharge into a Tidal River
无
2000-01-01
This paper analyzes the mixing zone of a vertical discharge of sewage into a natural tidal river with strong tidal currents. The paper presents a numerical model, which combines 1-D and 2-D models to compute the mixing zone for the Sibao Segment of the Qiantang River. The simple 1-D model was used to model the flow for the entire river using field data as the boundary conditions. The complete depth-averaged turbulence model was used for the 2-D computation. The calculated results agree well with the field observations. The analysis provides a practical method for the computation of mixing zones in tidal rivers.
Uncertainty analysis of numerical model simulations and HFR measurements during high energy events
Donncha, Fearghal O.; Ragnoli, Emanuele; Suits, Frank; Updyke, Teresa; Roarty, Hugh
2013-04-01
The identification and decomposition of sensor and model shortcomings is a fundamental component of any coastal monitoring and predictive system. In this research, numerical model simulations are combined with high-frequency radar (HFR) measurements to provide insights into the statistical accuracy of the remote sensing unit. A combination of classical tidal analysis and quantitative measures of correlation evaluate the performance of both across the bay. A network of high frequency radars is deployed within the Chesapeake study site, on the East coast of the United States, as a backbone component of the Integrated Ocean Observing System (IOOS). This system provides real-time synoptic measurements of surface currents in the zonal and meridional direction at hourly intervals in areas where at least two stations overlap, and radial components elsewhere. In conjunction with this numerical simulations using EFDC (Environmental Fluid Dynamics Code), an advanced three-dimensional model, provide additional details on flows, encompassing both surface dynamics and volumetric transports, while eliminating certain fundamental error inherent in the HFR system such as geometric dilution of precision (GDOP) and range dependencies. The aim of this research is an uncertainty estimate of both these datasets allowing for a degree of inaccuracy in both. The analysis focuses on comparisons between both the vector and radial component of flows returned by the HFR relative to numerical predictions. The analysis provides insight into the reported accuracy of both the raw radial data and the post-processed vector current data computed from combining the radial data. Of interest is any loss of accuracy due to this post-processing. Linear regression techniques decompose the surface currents based on dominant flow processes (tide and wind); statistical analysis and cross-correlation techniques measure agreement between the processed signal and dominant forcing parameters. The tidal signal
Zhi-yue Zhang
2002-01-01
Both numerical simulation and theoretical analysis of seawater intrusion in coastal regions are of great theoretical importance in environmental sciences. The mathematical model can be described as a coupled system of three dimensional nonlinear partial differential equations with initial-boundary value problems. In this paper, according to the actual conditions of molecular and three-dimensional characteristic of the problem,we construct the characteristic finite element alternating-direction schemes which can be divided into three continuous one-dimensional problems. By making use of tensor product algorithm, and priori estimation theory and techniques, the optimal order estimates in H1 norm are derived for the error in the approximate solution.
Error analysis of numerical gravitational waveforms from coalescing binary black holes
Fong, Heather; Chu, Tony; Kumar, Prayush; Pfeiffer, Harald; Boyle, Michael; Hemberger, Daniel; Kidder, Lawrence; Scheel, Mark; Szilagyi, Bela; SXS Collaboration
2016-03-01
The Advanced Laser Interferometer Gravitational-wave Observatory (Advanced LIGO) has finished a successful first observation run and will commence its second run this summer. Detection of compact object binaries utilizes matched-filtering, which requires a vast collection of highly accurate gravitational waveforms. This talk will present a set of about 100 new aligned-spin binary black hole simulations. I will discuss their properties, including a detailed error analysis, which demonstrates that the numerical waveforms are sufficiently accurate for gravitational wave detection purposes, as well as for parameter estimation purposes.
Temporal scaling analysis of irradiance estimated from daily satellite data and numerical modelling
Vindel, Jose M.; Navarro, Ana A.; Valenzuela, Rita X.; Ramírez, Lourdes
2016-11-01
The temporal variability of global irradiance estimated from daily satellite data and numerical models has been compared for different spans of time. According to the time scale considered, a different behaviour can be expected for each climate. Indeed, for all climates and at small scale, the persistence decreases as this scale increases, but the mediterranean climate, and its continental variety, shows higher persistence than oceanic climate. The probabilities of maintaining the values of irradiance after a certain period of time have been used as a first approximation to analyse the quality of each source, according to the climate. In addition, probability distributions corresponding to variations of clearness indices measured at several stations located in different climate zones have been compared with those obtained from satellite and modelling estimations. For this work, daily radiation data from the reanalysis carried out by the European Centre for Medium-Range Weather Forecasts and from the Satellite Application Facilities on climate monitoring have been used for mainland Spain. According to the results, the temporal series estimation of irradiance is more accurate when using satellite data, independent of the climate considered. In fact, the coefficients of determination corresponding to the locations studied are always above 0.92 in the case of satellite data, while this coefficient decreases to 0.69 for some cases of the numerical model. This conclusion is more evident in oceanic climates, where the most important errors can be observed. Indeed, in this case, the RRMSE derived from the CM-SAF estimations is 20.93%, while in the numerical model, it is 48.33%. Analysis of the probabilities corresponding to variations in the clearness indices also shows a better behaviour of the satellite-derived estimates for oceanic climate. For the standard mediterranean climate, the satellite also provides better results, though the numerical model improves
Managing tourist harbors: are managers aware of the real environmental risks?
Petrosillo, Irene; Valente, Donatella; Zaccarelli, Nicola; Zurlini, Giovanni
2009-10-01
The management of tourist harbors has traditionally been analyzed with little attention to managers' awareness of the effects of their decisions on the environment. The aims of this paper were to assess managers' perceptions of the main environmental risks in their regions and to identify common behaviors among the managers involved in eight tourist harbors in southern Italy, where the same tourist harbor is often managed by different managers. A questionnaire was administered and statistical analyses were performed to test differences between managers of big and small harbors. Managers showed a low perception of environmental risks and, surprisingly, in certain harbors, some meaningful cases were highlighted: the most homogeneous case, where all managers showed a reasonable level of environmental awareness, and cases with strong mismatches among managers. In this paper, we propose that an assessment of managers' perceptions of risk be included as a new form of analysis when environmental risk assessments are carried out.
Rasmussen, Robert Gary
Several topics relating to the objective analysis of humidity for regional scale numerical weather prediction are investigated. These include: (1) sampling the humidity field; (2) choosing an analysis scheme; (3) choosing an analysis variable; (4) using surface data to diagnose upper -air humidity (SFC-DIAG); (5) using cloud analysis data to diagnose surface and upper-air humidities (3DNEPH-DIAG); and (6) modeling the humidity lateral autocorrelation function. Regression equations for the diagnosed humidities and several correlation models are developed and validated. Four types of data are used in a preliminary demonstration: observations (radiosonde and surface), SFC-DIAG data, 3DNEPH-DIAG data, and forecast data from the Drexel/NCAR Limited-Area and Mesoscale Prediction System (LAMPS). The major conclusions are: (1) independent samples of relative humidity can be obtained by sampling at intervals of two days and 1750 km, on the average; (2) Gandin's optimum interpolation (OI) is preferable to Cressman's successive correction and Panofsky's surface fitting schemes; (3) relative humidity (RH) is a better analysis variable than dew-point depression; (4) RH*, the square root of (1-RH), is better than RH; (5) both surface and cloud analysis data can be used to diagnose the upper-air humidity; (6) pooling dense data prior to OI analysis can improve the quality of the analysis and reduce its computational burden; (7) iteratively pooling data is economical; (8) for the types of data considered, use of more than about eight data in an OI point analysis cannot be justified by expectations of further reducing the analysis error variance; and (9) the statistical model in OI is faulty in that an analyzed humidity can be biased too much toward the first guess.
Liang, Fayun; Chen, Haibing; Huang, Maosong
2017-07-01
To provide appropriate uses of nonlinear ground response analysis for engineering practice, a three-dimensional soil column with a distributed mass system and a time domain numerical analysis were implemented on the OpenSees simulation platform. The standard mesh of a three-dimensional soil column was suggested to be satisfied with the specified maximum frequency. The layered soil column was divided into multiple sub-soils with a different viscous damping matrix according to the shear velocities as the soil properties were significantly different. It was necessary to use a combination of other one-dimensional or three-dimensional nonlinear seismic ground analysis programs to confirm the applicability of nonlinear seismic ground motion response analysis procedures in soft soil or for strong earthquakes. The accuracy of the three-dimensional soil column finite element method was verified by dynamic centrifuge model testing under different peak accelerations of the earthquake. As a result, nonlinear seismic ground motion response analysis procedures were improved in this study. The accuracy and efficiency of the three-dimensional seismic ground response analysis can be adapted to the requirements of engineering practice.
LIU Hou-lin; LIU Dong-xi; WANG Yong; WU Xian-fang; WANG Jian; DU Hui
2013-01-01
This paper studies the attached sheet cavitation in centrifugal pumps.A pump casted from Perspex is used as the test subject.The cavitation bubbles were observed in the entrance of the impeller and the drops of the head coefficients were measured under different operating conditions.A Filter-Based Model (FBM),derived from the RNG k-ε model,and a modified Zwart model are adopted in the numerical predictions of the unsteady cavitating flows in the pump.The simulations are carried out and the results are compared with experimental results for 3 different flow coefficients,from 0.077 to 0.114.Under four operating conditions,qualitative comparisons are made between experimental and numerical cavitation patterns,as visualized by a high-speed camera and described as isosurfaces of the vapour volume fraction αv =0.1.It is shown that the simulation can truly represent the development of the attached sheet cavitation in the impeller.At the same time,the curves for the drops of the head coefficients obtained from experiments and calculations are also quantitatively compared,which shows that the decline of the head coefficients at every flow coefficient is correctly captured,and the prediction accuracy is high.In addition,the detailed analysis is made on the vapour volume fraction contours on the plane of span is 0.5 and the loading distributions around the blade section at the midspan.It is shown that the FBM model and the modified Zwart model are effective for the numerical simulation of the cavitating flow in centrifugal pumps.The analysis results can also be used as the basis for the further research of the attached sheet cavitation and the improvement of centrifugal pumps.
Numerical Analysis of Composite Steel Concrete Structural Shear Walls with Steel Encased Profiles
Daniel Dan
2009-01-01
Full Text Available The use of common reinforced concrete shear walls in high rise buildings is sometimes limited because of the large amount of reinforcement localized at the end of the element. A good alternative in avoiding this disadvantage is to use composite steel concrete structural shear walls with steel encased profiles. This solution used for high rise buildings, offers to designers lateral stiffness, shear capacity and high bending resisting moment of structural walls. The encasement of the steel shapes in concrete is applied also for the following purposes: flexural stiffening and strengthening of compression elements; fire protection; potentially easier repairs after moderate damage; economy with respect both to material and construction. Until now in the national and international literature poor information about nonlinear behaviour of composite steel concrete structural shear walls with steel encased profiles is available. A theoretical and experimental program related to the behaviour of steel concrete structural shear walls with steel encased profiles is developed at “Politehnica” University of Timişoara. The program refers to six different elements, which differ by the shape of the steel encased profile and also by the arrangement of steel shapes on the cross section of the element. In order to calibrate the elements for experimental study some numerical analysis were made. The paper presents the results of numerical analysis with details of stress distribution, crack distribution, structural stiffness at various loads, and load bearing capacity of the elements.
A Mathematical and Numerical Model for the Analysis of Hybrid Rocket Motors
Florin MINGIREANU
2011-12-01
Full Text Available The hybrid rocket motors (HRM use a two-phase propellant system. This offers some remarkable advantages but also arises some difficulties like the neutralization of their instabilities. The non-acoustic combustion instabilities are high-amplitude pressure oscillations that have too low frequencies to be associated with acoustics. Acoustic type combustion instabilities are self-excited oscillations generated by the interaction between acoustic waves and combustion. The goal of the present work is to develop a simplified model of the coupling of the hybrid combustion process with the complete unsteady flow, starting from the combustion port and ending with the nozzle. This model must be useful for transient and stability analysis and also for scaling of HRMs. The numerical results obtained with our model show a good agreement with published experimental and numerical results. The computational and stability analysis models developed in this work are simple, computationally efficient and offer the advantage of taking into account a large number of functional and constructive parameters that are used by the engineers.
2008-01-01
Nonlinear parametric vibration of axially accelerating viscoelastic beams is inves-tigated via an approximate analytical method with numerical confirmations. Based on nonlinear models of a finite-small-stretching slender beam moving at a speed with a periodic fluctuation, a solvability condition is established via the method of multiple scales for subharmonic resonance. Therefore, the amplitudes of steady-state periodic responses and their existence conditions are derived. The amplitudes of stable steady-state responses increase with the amplitude of the axial speed fluctuation, and decrease with the viscosity coefficient and the nonlinear coefficient. The minimum of the detuning parameter which causes the existence of a stable steady-state periodic response decreases with the amplitude of the axial speed fluctuation, and increases with the viscosity coefficient. Nu-merical solutions are sought via the finite difference scheme for a nonlinear par-tial-differential equation and a nonlinear integro-partial-differential equation. The calculation results qualitatively confirm the effects of the related parameters pre-dicted by the approximate analysis on the amplitude and the existence condition of the stable steady-state periodic responses. Quantitative comparisons demonstrate that the approximate analysis results have rather high precision.
Xia, X.; Zhang, H. Y.; Deng, Y. C.
2016-08-01
Solid-fluid phase change materials have been of increasing interest in various applications due to their high latent heat with minimum volume change. In this work, numerical analysis of phase change materials is carried out for the purpose of thermal control of the cylindrical power battery cells for applications in electric vehicles. Uniform heat density is applied at the battery cell, which is surrounded by phase change material (PCM) of paraffin wax type and contained in a metal housing. A two-dimensional geometry model is considered due to the model symmetry. The effects of power densities, heat transfer coefficients and onset melting temperatures are examined for the battery temperature evolution. Temperature plateaus can be observed from the present numerical analysis for the pure PCM cases, with the temperature level depending on the power densities, heat transfer coefficients, and melting temperatures. In addition, the copper foam of high thermal conductivity is inserted into the copper foam to enhance the heat transfer. In the modeling, the local thermal non-equilibrium between the metal foam and the PCM is taken into account and the temperatures for the metal foam and PCM are obtained respectively.
Numerical analysis and field monitoring tests on shallow tunnels under weak surrounding rock
刘建华; 刘晓明; 张永杰; 肖庭
2015-01-01
The Jianpudong No. 4 tunnel is a shallow tunnel, which belongs to Shaoshan County scenic highway in Hunan province, China and whose surrounding rock is weak. According to its characteristics, the field monitoring tests and numerical analysis were done. The mechanical characteristics of shallow tunnels under weak surrounding rock and the stress−strain rule of surrounding rock and support were analyzed. The numerical analysis results show that the settlement caused by upper bench excavating accounts for 44% of the total settlement, and the settlement caused by tunnel upper bench supporting accounts for 56% of the total settlement. The maximum axial force of shotcrete lining is 177.2 kN, which locates in hance under the secondary lining. The maximum moment of shotcrete lining is 5.08 kN·m, which locates in the arch foot. The stress curve of steel arch has three obvious stages during the tunnel construction. The maximum axial force of steel arch is 297.4 kN, which locates in tunnel vault. The axial forces of steel arch are respectively 23.5 kN and−21.8 kN, which is influenced by eccentric compression of shallow tunnel and locates in hance. The results show that there is larger earth pressure in tunnel vault which is most unfavorable position of steel arch. Therefore, the advance support should be strengthened in tunnel vault during construction process.
[Subordination of the taxa of gram-negative bacteria determined by numerical analysis methods].
Romanovskaia, V A; Sadovnikov, Iu S; Malashenko, Iu R; el-Said, M
1986-01-01
Various numerical methods were used to estimate the coordination of taxa of gram-negative aerobic and facultative anaerobic organoheterotrophic and chemolithotrophic bacteria. Stable phena were found to be formed by cultures belonging to the families Rhizobiaceae, Halobacteriaceae, Enterobacteriaceae, Nitrobacteriaceae (except the genus Nitrobacter), and Methylomonadaceae (except the genus Methylococcus). The unstable position was found in the genera Thermus, Zoogloea, Xanthomonas, Sulfolobus, Methylococcus, Alcaligenes, Brucella, and Acetobacter. The greatest scatter among the objects being analysed was detected among genera belonging to the family Pseudomonadaceae. The taxonomic position of these genera must be defined more precisely. The family Methylomonadaceae is related to such physiologically unique groups of microorganisms as nitrifying, sulfate-reducing, extreme thermophilic and halophilic forms. All in all, the data reported in this work show that numerical analysis can be used to specify the classification structure of bacteria. In a number of cases, the results are consistent with those changes which are performed in the Bergey Manual 9 using logical analysis (for instance, concerning the position of the genera Gluconobacter, Acetobacter, Beijerinckia, and Derxia).
Numerical analysis of thermal environment control in high density data center
Kwon, Oh Kyung; Kim, Hyeon Joong; Cha, Dong An [Korea Institute of Industrial Technology, Cheonan (Korea, Republic of)
2012-08-15
Increasing heat generation in CPUs can hamper effective recirculation and by pass because of the large temperature difference between the exhaust and the intake air through a server room. This increases the overall temperature inside a data center and decreases the efficiency of the data center's cooling system. The purpose of the data center's cooling system is to separate the intake and exhaust air by controlling the computer room air conditioner(CRAC). In this study, ICEPAK is used to conduct a numerical analysis of a data center's cooling system. The temperature distribution and the entire room are analyzed for different volumetric flow rates. The optimized volumetric flow rate is found for each CPU power. The heat removal and temperature distribution for CPU powers of 100, 120, and 140W are found to be the best for a volumetric flow rate of 0.15m'3'/s. The numerical analysis is verified through RTI indicators, and the results appear to be the most reliable when the RTI value is 81.
Numerical Analysis of Deteriorated Sub-sea Pipelines under Environmental Loads
GÜCÜYEN Engin
2015-01-01
The significant point is the bidirectional interaction technique in FSI analysis while investigating subsea corrosion effect. By this way, pipe environment is accurately modelled and fluid effects are also considered. The effect of external corrosion defects on structural behaviour of a pipeline is studied by creating a nonlinear numerical model based on the finite element method according to ABAQUS analysis program. Corrosion losses of sections are obtained from experimental results and applied to the model. Numerical model is formed by a span of sub-sea pipeline that is subjected to environmental loads. Seismic and wind-generated irregular wave loads are considered as environmental loads. Irregular wave is represented with equivalent eight regular waves via FFT. The pipe is modelled according to two different types which are non-corroded(intact) and corroded (deteriorated) to demonstrate corrosion effects on it. The visible type of corrosion in marine environment is named ‘pitting’ corrosion, in which the material loss is locally interpenetrated over the surface. By considering this situation, the corroded and non-corroded pipes are modelled as 3D solid elements. The main point is revealing how the subsea corrosion affects the structural behaviour of pipelines on the basis of implementation of experimental results to a model structure due to changes of stresses and displacement.
Jinfeng Wang
2014-01-01
Full Text Available We discuss and analyze an H1-Galerkin mixed finite element (H1-GMFE method to look for the numerical solution of time fractional telegraph equation. We introduce an auxiliary variable to reduce the original equation into lower-order coupled equations and then formulate an H1-GMFE scheme with two important variables. We discretize the Caputo time fractional derivatives using the finite difference methods and approximate the spatial direction by applying the H1-GMFE method. Based on the discussion on the theoretical error analysis in L2-norm for the scalar unknown and its gradient in one dimensional case, we obtain the optimal order of convergence in space-time direction. Further, we also derive the optimal error results for the scalar unknown in H1-norm. Moreover, we derive and analyze the stability of H1-GMFE scheme and give the results of a priori error estimates in two- or three-dimensional cases. In order to verify our theoretical analysis, we give some results of numerical calculation by using the Matlab procedure.
Wang, Jinfeng; Zhao, Meng; Zhang, Min; Liu, Yang; Li, Hong
2014-01-01
We discuss and analyze an H(1)-Galerkin mixed finite element (H(1)-GMFE) method to look for the numerical solution of time fractional telegraph equation. We introduce an auxiliary variable to reduce the original equation into lower-order coupled equations and then formulate an H(1)-GMFE scheme with two important variables. We discretize the Caputo time fractional derivatives using the finite difference methods and approximate the spatial direction by applying the H(1)-GMFE method. Based on the discussion on the theoretical error analysis in L(2)-norm for the scalar unknown and its gradient in one dimensional case, we obtain the optimal order of convergence in space-time direction. Further, we also derive the optimal error results for the scalar unknown in H(1)-norm. Moreover, we derive and analyze the stability of H(1)-GMFE scheme and give the results of a priori error estimates in two- or three-dimensional cases. In order to verify our theoretical analysis, we give some results of numerical calculation by using the Matlab procedure.
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.
Numerical simulation and factor analysis of petrochemical pipe erosion-corrosion failure
XU, G. F.; OU, G. F.; Chen, T.; Li, P. X.; JIN, H. Z.
2016-05-01
Based on the behavior of carbon steel outlet tube in REAC pipes of Zhenhai Refining & Chemical Company, the mathematical model of fluid-solid interaction was established according to the mechanism of erosion-corrosion damage. The interaction between corrosion products protecting film and multiphase liquid was analyzed by numerical simulation method. The distribution of shearing stress on the inwall of elbow bend, and the distribution of principal displacement, stress and strain of corrosion products protecting film were disclosed, while the erosion-corrosion failure processes was studied. The simulation result coincides with that of the positioned thickness gauging which validated the reliability and feasibility of the finite element analysis software simulation method. The obtained results can be used in the erosion-corrosion failure analysis, structural optimization, in-service testing positioning, life prediction, risk assessment, safety and other security projects for multiphase flow pipeline.
Numerical Analysis on Air Ingress Behavior in GTHTR300-Cogeneration System
Takeda, Tetsuaki; Yan, Xing; Kunitomi, Kazuhiko
The objective of this study is to clarify safety characteristics of a High Temperature Gas-Cooled Reactor (HTGR) for the pipe rupture accident. Japan Atomic Energy Agency (JAEA) has been developing the analytical code for the safety characteristics of the HTGR and carrying out design study of the gas turbine high temperature reactor of 300MWe nominal-capacity for hydrogen production, the GTHTR300C (Gas Turbine High Temperature Reactor 300 for Cogeneration). A numerical analysis of heat and mass transfer fluid flow with multi-component gas mixture has been performed to obtain the variation of the density of the gas mixture, and the onset time of natural circulation of air. From the results obtained in this analysis, it was found that the duration time of the air ingress by molecular diffusion would increase due to the existence of the recuperator in the GTHTR300C system.
Numerical analysis for finite-range multitype stochastic contact financial market dynamic systems.
Yang, Ge; Wang, Jun; Fang, Wen
2015-04-01
In an attempt to reproduce and study the dynamics of financial markets, a random agent-based financial price model is developed and investigated by the finite-range multitype contact dynamic system, in which the interaction and dispersal of different types of investment attitudes in a stock market are imitated by viruses spreading. With different parameters of birth rates and finite-range, the normalized return series are simulated by Monte Carlo simulation method and numerical studied by power-law distribution analysis and autocorrelation analysis. To better understand the nonlinear dynamics of the return series, a q-order autocorrelation function and a multi-autocorrelation function are also defined in this work. The comparisons of statistical behaviors of return series from the agent-based model and the daily historical market returns of Shanghai Composite Index and Shenzhen Component Index indicate that the proposed model is a reasonable qualitative explanation for the price formation process of stock market systems.
Analytical and Numerical funicular analysis by means of the Parametric Force Density Method
C. Cercadillo-García
2016-04-01
Full Text Available The funicular concept has often been used in different stages of structural analysis and design. This paper presents two new methods: Analytical, A-FDM, and Numerical method, N-FDM, based on a parametric application of the original Force Density Method (FDM. This is an especially useful way of visualizing a set of solutions and optimizing, i.e. selecting one specific funicular related to a set of constraints. Two structural algorithms are implemented iteratively with Maple® in real time, and output is also linked to AutoCAD®. Maple® facilitates control of geometrical constraints, while AutoCAD® helps to show all parameterized data. Because of their practical interest, special emphasis is placed on masonry structures using a Limit Analysis approach and preliminary design. Examples of the application of both methods are depicted.
FINITE VOLUME NUMERICAL ANALYSIS FOR PARABOLIC EQUATION WITH ROBIN BOUNDARY CONDITION
Xia Cui
2005-01-01
In this paper, finite volume method on unstructured meshes is studied for a parabolic convection-diffusion problem on an open bounded set of Rd (d = 2 or 3) with Robin boundary condition. Upwinding approximations are adapted to treat both the convection term and Robin boundary condition. By directly getting start from the formulation of the finite volume scheme, numerical analysis is done. By using several discrete functional analysis techniques such as summation by parts, discrete norm inequality, et al, the stability and error estimates on the approximate solution are established, existence and uniqueness of the approximate solution and the 1st order temporal norm and L2 and H1 spacial norm convergence properties are obtained.
NUMERICAL ANALYSIS OF AIRFLOW AND METHANE EMITTED FROM THE MINE FACE IN A BLIND DOG HEADING
Jarosław BRODNY
2015-04-01
Full Text Available Ventilation is one of the most common presented problems during the driving of dog headings. During driving such heading has only one connection with air stream routes, which significantly make difficult the process of its ventilation. In a case of its driving in coal in the methane seam, this heading is endangered also to methane emission. In such case process of its ventilation is much more difficult. In the paper there are presented results of numerical analysis of ventila-tion of blind dog headings using air-duct forcing the air into its mine face. The analysis was performed for four different velocities of the air at the outlet from air-duct. The calculations were made for the excavation of heading with heading machine and conveyor belt.
Numerical Analysis of Silicon Micromachined Gas Pendulum Tilt Sense Organ Temperature Field
Linhua Piao; Bin Zhang; Yaojie Lv; Fuxue Zhang
2006-01-01
An analysis of the sensitive mechanism of silicon micromachined gas pendulum tilt sense organ is made. Adopting the method of FEA (finite element analysis), the temperature field at two points heat source, when the two-dimensional enclosure was inclined, was obtained by application of the program ANSYS-FLOTRAN CFD and a series of procedures, such as modeling, meshing, loading and equation solving. The numerical results show that in the level state, the temperatures at two points heat source are two points in the same isotherm; however, the temperatures are not the same when the enclosure is inclined. The difference of the temperatures will increase with the augment of the tilt angle, and contrarily it will decrease. That is the characteristic used to sense the transformation of obliquity.
NUMERICAL ANALYSIS OF STRIKE OF PISTON TO CYLINDER UNDER SUPERCHARGE CONDITIONS
余志壮; 宋正华; 董光能; 谢友柏
2004-01-01
Objective To investigate the changes to the strike extent of piston to cylinder after engine supercharge design. Methods The lubrication model between the skirt of piston and liner is established by means of piston dynamics, combined with the hydrodynamic lubrication equation. Optimized numerical analysis method is employed in solving the dynamics and lubrication equations. The analyses about piston strike under two combustion gas pressures are performed. Results The peak values of maximum eccentricity under supercharge condition are much greater than under non-supercharge condition, which means a stronger impulsion of piston to cylinder wall and a greater possibility of scuffing. The horizontal velocities of piston in supercharge condition are larger, which illuminate the more unstable motion state. Conclusion The analysis gives a new conclusion. Combustion gas pressure plays an important role in the piston strike motion. Influences of supercharge should be taken into account so that the traditional product test items can be improved.
Numerical Analysis of Characteristics of a Particulate Debris Bed Coolability with Single Phase flow
Lee, Jew-han; Chang, Soon-heung [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Cho, Chung-ho; Lee, Yong-bum [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2008-05-15
Designed on the basis of defense-in-depth concept, liquid metal cooled reactor, such as KALIMER-600 is unlikely to undergo the hypothetical core disruptive accident (HCDA). However in case of accident, there exists a possibility of re-criticality and vessel melting when core melt-down occurs. For this reason, the analysis on the ability of post-accident heat removal (PAHR) should be preceded. As a part of this, single phase flow coolability analysis of the particulate debris bed formed at the top of core catcher has been performed to achieve in-vessel fuel retention. The forming process of particulate debris bed is described and single phase cooling model with numerical results are presented.
Numerical analysis for finite-range multitype stochastic contact financial market dynamic systems
Yang, Ge; Wang, Jun [School of Science, Beijing Jiaotong University, Beijing 100044 (China); Fang, Wen, E-mail: fangwen@bjtu.edu.cn [School of Economics and Management, Beijing Jiaotong University, Beijing 100044 (China)
2015-04-15
In an attempt to reproduce and study the dynamics of financial markets, a random agent-based financial price model is developed and investigated by the finite-range multitype contact dynamic system, in which the interaction and dispersal of different types of investment attitudes in a stock market are imitated by viruses spreading. With different parameters of birth rates and finite-range, the normalized return series are simulated by Monte Carlo simulation method and numerical studied by power-law distribution analysis and autocorrelation analysis. To better understand the nonlinear dynamics of the return series, a q-order autocorrelation function and a multi-autocorrelation function are also defined in this work. The comparisons of statistical behaviors of return series from the agent-based model and the daily historical market returns of Shanghai Composite Index and Shenzhen Component Index indicate that the proposed model is a reasonable qualitative explanation for the price formation process of stock market systems.
Numerical analysis for finite-range multitype stochastic contact financial market dynamic systems
Yang, Ge; Wang, Jun; Fang, Wen
2015-04-01
In an attempt to reproduce and study the dynamics of financial markets, a random agent-based financial price model is developed and investigated by the finite-range multitype contact dynamic system, in which the interaction and dispersal of different types of investment attitudes in a stock market are imitated by viruses spreading. With different parameters of birth rates and finite-range, the normalized return series are simulated by Monte Carlo simulation method and numerical studied by power-law distribution analysis and autocorrelation analysis. To better understand the nonlinear dynamics of the return series, a q-order autocorrelation function and a multi-autocorrelation function are also defined in this work. The comparisons of statistical behaviors of return series from the agent-based model and the daily historical market returns of Shanghai Composite Index and Shenzhen Component Index indicate that the proposed model is a reasonable qualitative explanation for the price formation process of stock market systems.
A numerical analysis model for interpretation of flow cytometric studies of ex vivo phagocytosis.
Ted S Strom
Full Text Available The study of ex vivo phagocytosis via flow cytometry requires that one distinguish experimentally between uptake and adsorption of fluorescently labeled targets by phagocytes. Removal of the latter quantity from the analysis is the most common means of analyzing such data. Because the probability of phagocytosis is a function of the probability of adsorption, and because partially quenched fluorescence after uptake often overlaps with that of negative controls, this approach is suboptimal at best. Here, we describe a numerical analysis model which overcomes these limitations. We posit that the random adsorption of targets to macrophages, and subsequent phagocytosis, is a function of three parameters: the ratio of targets to macrophages (m, the mean fluorescence intensity imparted to the phagocyte by the internalized target (alpha, and the probability of phagocytosis per adsorbed target (p. The potential values of these parameters define a parameter space and their values at any point in parameter space can be used to predict the fraction of adsorption(+ and [adsorption(-, phagocytosis(+] cells that might be observed experimentally. By systematically evaluating the points in parameter space for the latter two values and comparing them to experimental data, the model arrives at sets of parameter values that optimally predict such data. Using activated THP-1 cells as macrophages and platelets as targets, we validate the model by demonstrating that it can distinguish between the effects of experimental changes in m, alpha, and p. Finally, we use the model to demonstrate that platelets from a congenitally thrombocytopenic WAS patient show an increased probability of ex vivo phagocytosis. This finding correlates with other evidence that rapid in vivo platelet consumption contributes significantly to the thrombocytopenia of WAS. Our numerical analysis method represents a useful and innovative approach to multivariate analysis.
Dalai, Banzragch; Ishiga, Hiroaki
2014-05-01
Large-scale harbor and settlement sites from the latter half of the eleventh through sixteenth centuries have recently been discovered in the northern part of Masuda City, Shimane Prefecture, Japan. The sites were constructed at the river mouth delta of the Takatsu and Masuda rivers, facing the Sea of Japan. In former time, the mouths of the two rivers are thought to have formed a shallow lagoon connecting with the Sea of Japan. The harbor was thus well located for ships sailing along the sea coast, especially for conducting trade with the China mainland and the Korean peninsula. Archaeological investigations have identified over 800 construction pits, blacksmith hearths, harbor structures and numerous fragments of ceramic porcelain originating both from within Japan and from Asia (China, Korea, Vietnam and Thailand). It seems that the maritime trade network operated from this Medieval harbor site by the Masuda Clan was on an East Asian scale. Consequently, the harbor site can be expected to have received a considerable amount of ancient anthropogenic matter. Concentrations of 22 elements in 66 soil samples from the Nakazu Higashihara site were determined by X-ray fluorescence spectroscopy, in order to identify the land use and human impacts on soil chemistry at the harbor site. The results show that significant differences in geochemical compositional exist between the northern and southern parts of the site due to differences in lithology and land use practice. The south area was a production area of this harbor site. Three different activity areas were recognized within this area (fire pit and charcoal area, building pillars, and a blacksmith furnace area), based on geochemical and archaeological information. Cluster analysis shows a strong relationship exists between As, Pb, Cu, Br, TS, MnO and P2O5 in the fire pit and charcoal area. These charcoal materials were likely derived from fuel used in firing and heating. Close relationships occur between Cr, Sr, Sc
Chanjo Woo
2017-07-01
Full Text Available The present study numerically analyzed the dynamic behavior of 3D framed structures subject to impulsive slamming forces by violent breaking waves. The structures were modeled using multiple lumped masses for the vertical projections of each member, and the slamming forces from the breaking waves were concentrated on these lumped masses. A numerical algorithm was developed to properly incorporate the slamming forces into a dynamic analysis to numerically determine the structural responses. Then, the validity of the numerical analysis was verified using the results of an existing hydraulic experiment. The numerical and experimental results for various model structures were generally in good agreement. The uncertainties concerning the properties of the breaking waves used in the verification are also discussed here.
Numerical analysis of regular waves over an onshore oscillating water column
Davyt, D.P.; Teixeira, P.R.F. [Universidade Federal do Rio Grande (FURG), RS (Brazil)], E-mail: pauloteixeira@furg.br; Ramalhais, R. [Universidade Nova de Lisboa, Caparica (Portugal). Fac. de Ciencias e Tecnologia; Didier, E. [Laboratorio Nacional de Engenharia Civil, Lisboa (Portugal)], E-mail: edidier@lnec.pt
2010-07-01
The potential of wave energy along coastal areas is a particularly attractive option in regions of high latitude, such as the coasts of northern Europe, North America, New Zealand, Chile and Argentina where high densities of annual average wave energy are found (typically between 40 and 100 kW/m of wave front). Power estimated in the south of Brazil is 30kW/m, creating a possible alternative of source energy in the region. There are many types and designs of equipment to capture energy from waves under analysis, such as the oscillating water column type (OWC) which has been one of the first to be developed and installed at sea. Despite being one of the most analyzed wave energy converter devices, there are few case studies using numerical simulation. In this context, the numerical analysis of regular waves over an onshore OWC is the main objective of this paper. The numerical models FLUINCO and FLUENT are used for achieving this goal. The FLUINCO model is based on RANS equations which are discretized using the two-step semi-implicit Taylor-Galerkin method. An arbitrary Lagrangian Eulerian formulation is used to enable the solution of problems involving free surface movements. The FLUENT code (version 6.3.26) is based on the finite volume method to solve RANS equations. Volume of Fluid method (VOF) is used for modeling free surface flows. Time integration is achieved by a second order implicit scheme, momentum equations are discretized using MUSCL scheme and HRIC (High Resolution Interface Capturing) scheme is used for convective term of VOF transport equation. The case study consists of a 10.m deep channel with a 10 m wide chamber at its end. One meter high waves with different periods are simulated. Comparisons between FLUINCO and FLUENT results are presented. Free surface elevation inside the chamber; velocity distribution and streamlines; amplification factor (relation between wave height inside the chamber and incident wave height); phase angle (angular
2013-07-01
Conference Paper 3. DATES COVERED (From - To) 14 Jul 2013 – 19 Jul 2013 4. TITLE AND SUBTITLE Numerical Analysis of a Single Microchannel Within a High...propulsion spacecraft. It was found that despite the very small diameter of the microchannels , each design produced extreme temperature...2013, Minneapolis, MN, USA HT2013-17217 DRAFT NUMERICAL ANALYSIS OF A SINGLE MICROCHANNEL WITHIN A HIGH- TEMPERATURE HYDROGEN HEAT EXCHANGER FOR
Major Maciej
2016-12-01
Full Text Available In this paper numerical analysis considering the influence of dynamical force acting on wall made of concrete blocks with rubber inserts is presented. By examining the stress values on front and back surface of the analysed wall structure model, the effectiveness of proposed solution can be measured comparing to the wall made of concrete blocks without rubber inserts. Complete numerical analysis was performed in ADINA program.
Chignik small boat harbor planning aid report
US Fish and Wildlife Service, Department of the Interior — Unless additional salmon use data would indicate otherwise, harbor site 3 is considered the environmentally preferred alternative for construction of a small...
Genetics Home Reference: Floating-Harbor syndrome
... child may have bones more typical of a child of 2. However, bone age is usually normal by age 6 to 12. Delay in speech development (expressive language delay) may be severe in Floating-Harbor syndrome , ...
Granular Flow Dynamics on Earth, Moon, and Mars from analytical, numerical and field analysis
Lucas, A.; Mangeney, A.; Mhge, D.
2010-12-01
Prediction of landslides dynamics remains difficult in spite of a considerable body of work. A number of previous studies have been based on runout analysis in relation to mean dissipation calibration via the friction coefficient. However, the shape of the initial scar is generally unknown in real cases, which weakens landslide material spreading predictions and has alters calibration parameters of numerical models. We study numerically the effects of scar geometry on flow and distribution of the deposits and show that the initial shape of the scar, independent of the friction coefficient, does not affect the runout distance. In contrast, 3D tests show that the shape of the final deposits is a function of the scar geometry, and hence information on initial scar geometry and initial volume involved in the mass spreading may be retrieved from analysis of final deposit morphology. From an analytical solution we show here why the classical mobility (defined as the ratio between total height and runout distance) decreases when the volume increases, as is generally observed in geological data. We thus introduce analytically a new mobility variable obtained from geomorphic measurements reflecting the intrinsic dissipation independent of the aspect ratio, of the volume of the granular mass involved, of the underlying topography, and of the initial scar geometry. Comparison between experimental results, terrestrial, Lunar and Martian cases highlights a larger new mobility measure of natural granular flows compared to dry mass spreading simulated in the laboratory. In addition, landslides in a similar geological context give a single value showing the robustness of this new parameter. Finally, the new mobility provides a first order estimate of the effective friction required in models to reproduce the extent of the deposits in a given geological context. This enables a feedback analysis method for retrieving the volume and shape of the initial landslide material and then
Vinga Susana
2012-05-01
Full Text Available Abstract Background Chaos Game Representation (CGR is an iterated function that bijectively maps discrete sequences into a continuous domain. As a result, discrete sequences can be object of statistical and topological analyses otherwise reserved to numerical systems. Characteristically, CGR coordinates of substrings sharing an L-long suffix will be located within 2-L distance of each other. In the two decades since its original proposal, CGR has been generalized beyond its original focus on genomic sequences and has been successfully applied to a wide range of problems in bioinformatics. This report explores the possibility that it can be further extended to approach algorithms that rely on discrete, graph-based representations. Results The exploratory analysis described here consisted of selecting foundational string problems and refactoring them using CGR-based algorithms. We found that CGR can take the role of suffix trees and emulate sophisticated string algorithms, efficiently solving exact and approximate string matching problems such as finding all palindromes and tandem repeats, and matching with mismatches. The common feature of these problems is that they use longest common extension (LCE queries as subtasks of their procedures, which we show to have a constant time solution with CGR. Additionally, we show that CGR can be used as a rolling hash function within the Rabin-Karp algorithm. Conclusions The analysis of biological sequences relies on algorithmic foundations facing mounting challenges, both logistic (performance and analytical (lack of unifying mathematical framework. CGR is found to provide the latter and to promise the former: graph-based data structures for sequence analysis operations are entailed by numerical-based data structures produced by CGR maps, providing a unifying analytical framework for a diversity of pattern matching problems.
Klishin, G.S.; Seleznev, V.E.; Aleoshin, V.V. [RFNC-VNIIEF (Russian Federation)
1997-12-31
Gas industry enterprises such as main pipelines, compressor gas transfer stations, gas extracting complexes belong to the energy intensive industry. Accidents there can result into the catastrophes and great social, environmental and economic losses. Annually, according to the official data several dozens of large accidents take place at the pipes in the USA and Russia. That is why prevention of the accidents, analysis of the mechanisms of their development and prediction of their possible consequences are acute and important tasks nowadays. The accidents reasons are usually of a complicated character and can be presented as a complex combination of natural, technical and human factors. Mathematical and computer simulations are safe, rather effective and comparatively inexpensive methods of the accident analysis. It makes it possible to analyze different mechanisms of a failure occurrence and development, to assess its consequences and give recommendations to prevent it. Besides investigation of the failure cases, numerical simulation techniques play an important role in the treatment of the diagnostics results of the objects and in further construction of mathematical prognostic simulations of the object behavior in the period of time between two inspections. While solving diagnostics tasks and in the analysis of the failure cases, the techniques of theoretical mechanics, of qualitative theory of different equations, of mechanics of a continuous medium, of chemical macro-kinetics and optimizing techniques are implemented in the Conversion Design Bureau {number_sign}5 (DB{number_sign}5). Both universal and special numerical techniques and software (SW) are being developed in DB{number_sign}5 for solution of such tasks. Almost all of them are calibrated on the calculations of the simulated and full-scale experiments performed at the VNIIEF and MINATOM testing sites. It is worth noting that in the long years of work there has been established a fruitful and effective
Unsteady numerical analysis of the rotating stall in pump- turbine geometry
Ješe, U.; Fortes-Patella, R.
2016-11-01
Main challenges in energy sector nowadays are storing and recovering of a large amount of energy in a short time. Pumped Storage Power Plants (PSP), using reversible pump- turbines are among the most cost-efficient solution to answer these needs. To provide a rapid adjustment to the electrical grid, pump-turbines are subjects of quick switching between pumping and generating modes and to extended operation under off-design conditions. To maintain the stability of the grid, the continuous operating area of reversible pump-turbines must be free of hydraulic instabilities. One of the main sources of pumping mode instabilities is the presence of the rotating stall that occurs at the part load. It can be observed as periodic occurrence and decay of recirculation zones in the distributor regions. Consequently, the machine can be exposed to uncontrollable shift between the operating points with the significant discharge modification and the drop of the efficiency. The phenomenon is very complex, three-dimensional and demanding for the investigation. The paper presents cost- efficient numerical methodology that enables the accurate prediction and analysis of the rotating stall. The investigations were made on a reduced-scaled high head pump-turbine design. Unsteady numerical calculations were performed using code FINE/TurboTM and URANS equations. Local flow study was done to describe in details the governing mechanisms of the rotating stall. The analyses enable the investigations of the rotating stall frequencies, the number of stalled cells and the intensity of the rotating stall. Moreover, the unsteady calculations give very good prediction of the pump-turbine performance for both, stable and unstable operating regions. Numerical results show very good qualitative and quantitative agreement with the available experimental data.
Analysis and numerical simulation of the diffusive wave approximation of the shallow water equations
Santillana, Mauricio
In this dissertation, the quantitative and qualitative aspects of modeling shallow water flow driven mainly by gravitational forces and dominated by shear stress, using an effective equation often referred to in the literature as the diffusive wave approximation of the shallow water equations (DSW) are presented. These flow conditions arise for example in overland flow and water flow in vegetated areas such as wetlands. The DSW equation arises in shallow water flow models when special assumptions are used to simplify the shallow water equations and contains as particular cases: the Porous Medium equation and the time evolution of the p-Laplacian. It has been successfully applied as a suitable model to simulate overland flow and water flow in vegetated areas such as wetlands; yet, no formal mathematical analysis has been carried out addressing, for example, conditions for which weak solutions may exist, and conditions for which a numerical scheme can be successful in approximating them. This thesis represents a first step in that direction. The outline of the thesis is as follows. First, a survey of relevant results coming from the studies of doubly nonlinear diffusion equations that can be applied to the DSW equation when topographic effects are ignored, is presented. Furthermore, an original proof of existence of weak solutions using constructive techniques that directly lead to the implementation of numerical algorithms to obtain approximate solutions is shown. Some regularity results about weak solutions are presented as well. Second, a numerical approach is proposed as a means to understand some properties of solutions to the DSW equation, when topographic effects are considered, and conditions for which the continuous and discontinuous Galerkin methods will succeed in approximating these weak solutions are established.
Numerical simulation and analysis for low-frequency rock physics measurements
Dong, Chunhui; Tang, Genyang; Wang, Shangxu; He, Yanxiao
2017-10-01
In recent years, several experimental methods have been introduced to measure the elastic parameters of rocks in the relatively low-frequency range, such as differential acoustic resonance spectroscopy (DARS) and stress-strain measurement. It is necessary to verify the validity and feasibility of the applied measurement method and to quantify the sources and levels of measurement error. Relying solely on the laboratory measurements, however, we cannot evaluate the complete wavefield variation in the apparatus. Numerical simulations of elastic wave propagation, on the other hand, are used to model the wavefield distribution and physical processes in the measurement systems, and to verify the measurement theory and analyze the measurement results. In this paper we provide a numerical simulation method to investigate the acoustic waveform response of the DARS system and the quasi-static responses of the stress-strain system, both of which use axisymmetric apparatus. We applied this method to parameterize the properties of the rock samples, the sample locations and the sensor (hydrophone and strain gauges) locations and simulate the measurement results, i.e. resonance frequencies and axial and radial strains on the sample surface, from the modeled wavefield following the physical experiments. Rock physical parameters were estimated by inversion or direct processing of these data, and showed a perfect match with the true values, thus verifying the validity of the experimental measurements. Error analysis was also conducted for the DARS system with 18 numerical samples, and the sources and levels of error are discussed. In particular, we propose an inversion method for estimating both density and compressibility of these samples. The modeled results also showed fairly good agreement with the real experiment results, justifying the effectiveness and feasibility of our modeling method.
You-Jun Ning; Xin-Mei An; Qing Lü; Guo-Wei Ma
2012-01-01
A complete rock failure process usually involves opening/sliding of preexisting discontinuities as well as fracturing in intact rock bridges to form persistent failure surfaces and subsequent motions of the generated rock blocks.The recently developed numerical manifold method (NMM)has potential for modelling such a complete failure process.However,the NMM suffers one limitation,i.e.,unexpected material domain area change occurs in rotation modelling.This problem can not be easily solved because the rigid body rotation is not represented explicitly in the NMM.The discontinuous deformation analysis (DDA) is specially developed for modelling discrete block systems.The rotationinduced material area change in the DDA modelling can be avoided conveniently because the rigid body rotation is represented in an explicit form.In this paper,a transition technique is proposed and implemented to convert a NMM modelling to a DDA modelling so as to simulate a complete rock failure process entirely by means of the two methods,in which the NMM is adopted to model the early fracturing as well as the transition from continua to discontinua,while the DDA is adopted to model the subsequent motion of the generated rock blocks.Such a numerical approach also improves the simulation efficiency greatly as compared with a complete NMM modelling approach.The fracturing of a rock slab with pre-existing non-persistent joints located on a slope crest and the induced rockfall process are simulated.The validity of the modelling transition from the NMM to the DDA is verified and the applicability of the proposed numerical approach is investigated.
Suarez-Rivera, Roberto; Martin, J. Wesley [TerraTek, Rio de Janeiro, RJ (Brazil); Begnaud, Bill J. [BHP Billiton Petroleum (Americas) Inc. (United States)
2004-07-01
This paper discusses the numerical (3D FEA) modeling of open hole, horizontal, multilateral junctions, to evaluate their mechanical stability under various conditions of junction length, junction orientation, in-situ stress, and rock strength, during drilling and production operations. The objective of the numerical analysis is to evaluate the risk of multilateral junction failure associated to changes in the above parameters for the prediction of minimum rock strength (UCS) required for placing the junction, and for minimizing the risk of junction failure, under various conditions of drawdown and depletion. Results provide clear guidelines for multilateral junction construction (i.e., multilateral geometry), placement (i.e., minimum required rock strength) and safe conditions of operation (i.e., drawdown and depletion). Results also provide critical conditions of drawdown and depletion as a function of rock strength. Furthermore, 3D FEA results show that because of the asymmetry in the junction geometry, the resulting bending moments that develop along the mother-bore and the lateral wellbores reduce the mechanical stability of the multilateral junction. This effect cannot be adequately represented by 2D plane-strain solutions. The discussed methodology will minimize the risk of junction failures resulting in considerable savings to the operator. (author)
Numerical Analysis of Heat Transfer in Fire-Protective Coatings Deformable upon Heating
Rudzinsky, V. P.; Garashchenko, A. N.
2016-02-01
Numerical studies of heat transfer in fire-protective coatings deformable (intumescent) upon heating have been conducted. The optimum combination of the computation-scheme parameters providing stability, convergence and satisfactory accuracy of solutions has been determined. An effect of basic characteristics of materials in real range of their change that made it possible to estimate the degree of influence of properties on the fire-protective efficiency of coatings and the level of warm-up (flame resistance) of structures to be protected with them has been studied. The possibility of using developed models and techniques to estimate and provide the required level of fire safety of polymer-based materials (in particular, elastomers and structures and products on their basis) is considered. The results of estimating the mass rate of evolving gaseous thermal-decomposition products that determine, in a considerable extent, the material combustibility have been presented. The numerical analysis results have demonstrated the potentiality of reducing the combustibility of such materials and increasing limits of their fire resistance at the expense of organizing the intumescence of a material upon heating by means of modification of their initial formulations as well as with the aid of an additional layer made of the intumescent coating compatible with an elastomer.
Linear stability analysis in the numerical solution of initial value problems
van Dorsselaer, J. L. M.; Kraaijevanger, J. F. B. M.; Spijker, M. N.
This article addresses the general problem of establishing upper bounds for the norms of the nth powers of square matrices. The focus is on upper bounds that grow only moderately (or stay constant) where n, or the order of the matrices, increases. The so-called resolvant condition, occuring in the famous Kreiss matrix theorem, is a classical tool for deriving such bounds.Recently the classical upper bounds known to be valid under Kreiss's resolvant condition have been improved. Moreover, generalizations of this resolvant condition have been considered so as to widen the range of applications. The main purpose of this article is to review and extend some of these new developments.The upper bounds for the powers of matrices discussed in this article are intimately connected with the stability analysis of numerical processes for solving initial(-boundary) value problems in ordinary and partial linear differential equations. The article highlights this connection.The article concludes with numerical illustrations in the solution of a simple initial-boundary value problem for a partial differential equation.
He, Jianbin; Yu, Simin; Cai, Jianping
2016-12-01
Lyapunov exponent is an important index for describing chaotic systems behavior, and the largest Lyapunov exponent can be used to determine whether a system is chaotic or not. For discrete-time dynamical systems, the Lyapunov exponents are calculated by an eigenvalue method. In theory, according to eigenvalue method, the more accurate calculations of Lyapunov exponent can be obtained with the increment of iterations, and the limits also exist. However, due to the finite precision of computer and other reasons, the results will be numeric overflow, unrecognized, or inaccurate, which can be stated as follows: (1) The iterations cannot be too large, otherwise, the simulation result will appear as an error message of NaN or Inf; (2) If the error message of NaN or Inf does not appear, then with the increment of iterations, all Lyapunov exponents will get close to the largest Lyapunov exponent, which leads to inaccurate calculation results; (3) From the viewpoint of numerical calculation, obviously, if the iterations are too small, then the results are also inaccurate. Based on the analysis of Lyapunov-exponent calculation in discrete-time systems, this paper investigates two improved algorithms via QR orthogonal decomposition and SVD orthogonal decomposition approaches so as to solve the above-mentioned problems. Finally, some examples are given to illustrate the feasibility and effectiveness of the improved algorithms.
Yang Ning
2016-02-01
Full Text Available The flutter characteristics of folding control fins with freeplay are investigated by numerical simulation and flutter wind tunnel tests. Based on the characteristics of the structures, fins with different freeplay angles are designed. For a 0° angle of attack, wind tunnel tests of these fins are conducted, and vibration is observed by accelerometers and a high-speed camera. By the expansion of the connected relationships, the governing equations of fit for the nonlinear aeroelastic analysis are established by the free-interface component mode synthesis method. Based on the results of the wind tunnel tests, the flutter characteristics of fins with different freeplay angles are analyzed. The results show that the vibration divergent speed is increased, and the divergent speed is higher than the flutter speed of the nominal linear system. The vibration divergent speed is increased along with an increase in the freeplay angle. The developed free-interface component mode synthesis method could be used to establish governing equations and to analyze the characteristics of nonlinear aeroelastic systems. The results of the numerical simulations and the wind tunnel tests indicate the same trends and critical velocities.
Zhang, Senlin; Yong, Zhengdong; Shi, Yaocheng; He, Sailing
2016-01-01
A slotted nanobeam cavity (SNC) is utilized to trap a polystyrene (PS) particle with a radius of only 2 nm. The carefully designed SNC shows an ultrahigh Q factor of 4.5 × 107 while maintaining a small mode volume of 0.067(λ/nwater)3. Strongly enhanced optical trapping force is numerically demonstrated when the 2 nm PS particle is introduced into the central, slotted part of the SNC. In the vertical direction, the numerical calculation results show that a trapping stiffness of 0.4 pN/(nm · mW) around the equilibrium position and a trapping potential barrier of ~2000 kBT/mW can be reached. To our best knowledge, the trapping capability (trapping stiffness and trapping potential barrier) of the proposed structure significantly outperforms the theoretical results of those in previously reported work. In addition, the SNC system does not suffer from the metal induced heat issue that restricts the performance of state-of-the-art optical trapping systems involving plasmonic enhancement. Based on the proposed cavity, applications such as lab-on-a-chip platforms for nanoscale particle trapping and analysis can be expected in future. PMID:27786248
Numerical Analysis of Impurity Transport along Magnetic Field Lines in Tokamak Scrape-Off Layer
Chung, Tae Kyun; Hong, Sang Hee
1996-11-01
A flow of impurity ions along the magnetic field lines in tokamak SOL (scrape-off layer) is investigated by a one-dimensional numerical analysis. The background values of SOL plasma, fields such as density, velocity, temperature and electric field, are obtained from an edge plasma transport code EDGETRAN(A 2-D edge plasma transport code with limited and diverted tokamak configurations developed by Dr. Kihak Im at Seoul National University). Impurity ions are generated by ionizations of neutral atoms in tokamak. The density profile of neutral atoms is given at an initial state. Impurity ions in a single-charged state develop into multi-charged states by ionization and recombination reactions. Impurity productions at the divertor target plate by sputterings are also considered as main source terms. As a numerics, FDM(Finite Difference Method) is employed. The Neumann condition on impurity density and the Dirchlet condition on impurity velocity are provided for their boundary conditions at a symmetry plane of the layer. No strict boundary condition on the target plate is given except an external source prescribed by sputtering rates.
Zhang, Senlin; Yong, Zhengdong; Shi, Yaocheng; He, Sailing
2016-10-01
A slotted nanobeam cavity (SNC) is utilized to trap a polystyrene (PS) particle with a radius of only 2 nm. The carefully designed SNC shows an ultrahigh Q factor of 4.5 × 107 while maintaining a small mode volume of 0.067(λ/nwater)3. Strongly enhanced optical trapping force is numerically demonstrated when the 2 nm PS particle is introduced into the central, slotted part of the SNC. In the vertical direction, the numerical calculation results show that a trapping stiffness of 0.4 pN/(nm · mW) around the equilibrium position and a trapping potential barrier of ~2000 kBT/mW can be reached. To our best knowledge, the trapping capability (trapping stiffness and trapping potential barrier) of the proposed structure significantly outperforms the theoretical results of those in previously reported work. In addition, the SNC system does not suffer from the metal induced heat issue that restricts the performance of state-of-the-art optical trapping systems involving plasmonic enhancement. Based on the proposed cavity, applications such as lab-on-a-chip platforms for nanoscale particle trapping and analysis can be expected in future.
Cheng Ma
2016-01-01
Full Text Available This paper is a study of the numerical implementation of the spatial elastoplastic damage model of concrete by isogeometric analysis (IGA method from three perspectives: the geometric modeling and the numerical formulation via IGA method, the constitutive model of concrete, and the solution algorithms for the local and global problems. The plasticity of concrete is considered on the basis of a nonassociated flow rule, where a three-parameter Barcelona yield surface and a modified Drucker-Prager plastic potential are used. The damage evolution of concrete driven by the internal variables is expressed by a piecewise function. In the study, the return-mapping algorithm and the substepping strategy are used for stress updating, and a new dissipation-based arc-length method with constraint path that considers the combined contribution of plasticity and damage to the energy dissipation is employed to trace the equilibrium path. After comparisons between simulation results and experimental data, the use of the elastoplastic damage model in the framework of IGA approach is proven to be practical in reflecting material properties of concrete.
Numerical analysis of irradiated Am samples in experimental fast reactor Joyo
Sagara, Hiroshi; Yamamoto, Tetsuro; Shiba, Tomo-oki; Saito, Masaki [Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo, 1528550 (Japan); Koyama, Shin-ichi; Maeda, Shigetaka, E-mail: sagara@nr.titech.ac.jp [Japan Atomic Energy Agency, 4002 Nanta-cho, O-arai machi, Ibaraki, 3111393 (Japan)
2010-03-15
Americium is a key element to design the FBR based nuclear fuel cycle, because of its long-term high radiological toxicity as well as a resource of even-mass-number plutonium by its transmutation in reactors, which contributes the enhancement of proliferation resistance. The present paper deals with the numerical analysis of the Am sample irradiation in Joyo to examine the transmutation performance of pure isotope in fast neutron environment during the irradiation, and deals with the comparison with the experimental result to evaluate the accuracy of current available numerical tool. In {sup 241}Am pure isotope sample, the burn-up calculation of Am transmutation ratio and principal nuclides accumulation are agreed with the measured data within 1-{sigma} uncertainty caused of cross-section covariance. Isomeric ratio of {sup 242}Am in total {sup 241}Am capture reaction were calculated as 0.852{+-}0.016 in the core and 0.85{+-}0.025 in the axial and radial reactors. The current data and recently reported data by Koyama et. al 2008 support the latest version of nuclear data sets in ENDFB-VII and JENDL/AC-2008. From the view point of proliferation resistance, it was confirmed {sup 241}Amp reduces un-attractive Pu to abuse from the beginning to the end of irradiation, and it would have important role to denature Pu in future FBR based nuclear fuel cycle.
Numerical and dimensional analysis of nanoparticles transport with two-phase flow in porous media
El-Amin, Mohamed
2015-04-01
In this paper, a mathematical model and numerical simulation are developed to describe the imbibition of nanoparticles-water suspension into two-phase flow in a porous medium. The flow system may be changed from oil-wet to water-wet due to nanoparticles (which are also water-wet) deposition on surface of the pores. So, the model is extended to include the negative capillary pressure and mixed-wet relative permeability correlations to fit with the mixed-wet system. Moreover, buoyancy and capillary forces as well as Brownian diffusion and mechanical dispersion are considered in the mathematical model. An example of countercurrent imbibition in a core of small scale is considered. A dimensional analysis of the governing equations is introduced to examine contributions of each term of the model. Several important dimensionless numbers appear in the dimensionless equations, such as Darcy number Da, capillary number Ca, and Bond number Bo. Throughout this investigation, we monitor the changing of the fluids and solid properties due to addition of the nanoparticles using numerical experiments.
Nagabhushana, A.; Spiegel, M.; Adu, S.; Hayes, N.; Paul, D.; Trivedi, K.; Fairbee, B.; Zheng, H.; Gerrity, A.; Kotru, S.; Roy, S.; Barkey, M.; Burkett, S. L.
2012-04-01
Reliable damage detection is crucial for assessing the integrity of a structure. In this paper, a numerical study of a composite panel fabricated to simulate a crack is undertaken using finite element methods (FEM). The damage to be considered is a transverse crack which pre-exists in the structure. The finite element models are developed for an undamaged and a damaged composite panel to compute the change in Lamb wave response due to the existence of a crack. The model is validated using shear lag analysis applied at the crack. The results are verified experimentally by comparing the results for an undamaged composite panel and a composite panel fabricated with a simulated crack using the vacuum assisted resin transfer molding (VARTM) process. The responses for each panel are obtained using surface mounted lead zirconate titanate (PZT) actuators and sensors. PZT is used to generate Lamb waves which produce stress throughout the panel thickness. Propagation characteristics of Lamb waves are varied by the presence of damage. The sensor data provide reliable information about the integrity of the structure. Numerical results are compared to the sensor output to ensure accuracy of the damage detection system.