Approximate Assertional Reasoning Over Expressive Ontologies
Tserendorj, Tuvshintur
2010-01-01
In this thesis, approximate reasoning methods for scalable assertional reasoning are provided whose computational properties can be established in a well-understood way, namely in terms of soundness and completeness, and whose quality can be analyzed in terms of statistical measurements, namely recall and precision. The basic idea of these approximate reasoning methods is to speed up reasoning by trading off the quality of reasoning results against increased speed.
Approximate Reasoning with Fuzzy Booleans
Broek, van den P.M.; Noppen, J.A.R.
2004-01-01
This paper introduces, in analogy to the concept of fuzzy numbers, the concept of fuzzy booleans, and examines approximate reasoning with the compositional rule of inference using fuzzy booleans. It is shown that each set of fuzzy rules is equivalent to a set of fuzzy rules with singleton crisp ante
An approximate-reasoning-based method for screening high-level waste tanks for flammable gas
International Nuclear Information System (INIS)
The in situ retention of flammable gas produced by radiolysis and thermal decomposition in high-level waste can pose a safety problem if the gases are released episodically into the dome space of a storage tank. Screening efforts at Hanford have been directed at identifying tanks in which this situation could exist. Problems encountered in screening motivated an effort to develop an improved screening methodology. Approximate reasoning (AR) is a formalism designed to emulate the kinds of complex judgments made by subject matter experts. It uses inductive logic structures to build a sequence of forward-chaining inferences about a subject. AR models incorporate natural language expressions known as linguistic variables to represent evidence. The use of fuzzy sets to represent these variables mathematically makes it practical to evaluate quantitative and qualitative information consistently. The authors performed a pilot study to investigate the utility of AR for flammable gas screening. They found that the effort to implement such a model was acceptable and that computational requirements were reasonable. The preliminary results showed that important judgments about the validity of observational data and the predictive power of models could be made. These results give new insights into the problems observed in previous screening efforts
An approximate-reasoning-based method for screening high-level waste tanks for flammable gas
Energy Technology Data Exchange (ETDEWEB)
Eisenhawer, S.W.; Bott, T.F.; Smith, R.E.
1998-07-01
The in situ retention of flammable gas produced by radiolysis and thermal decomposition in high-level waste can pose a safety problem if the gases are released episodically into the dome space of a storage tank. Screening efforts at Hanford have been directed at identifying tanks in which this situation could exist. Problems encountered in screening motivated an effort to develop an improved screening methodology. Approximate reasoning (AR) is a formalism designed to emulate the kinds of complex judgments made by subject matter experts. It uses inductive logic structures to build a sequence of forward-chaining inferences about a subject. AR models incorporate natural language expressions known as linguistic variables to represent evidence. The use of fuzzy sets to represent these variables mathematically makes it practical to evaluate quantitative and qualitative information consistently. The authors performed a pilot study to investigate the utility of AR for flammable gas screening. They found that the effort to implement such a model was acceptable and that computational requirements were reasonable. The preliminary results showed that important judgments about the validity of observational data and the predictive power of models could be made. These results give new insights into the problems observed in previous screening efforts.
An approximate-reasoning-based method for screening flammable gas tanks
International Nuclear Information System (INIS)
High-level waste (HLW) produces flammable gases as a result of radiolysis and thermal decomposition of organics. Under certain conditions, these gases can accumulate within the waste for extended periods and then be released quickly into the dome space of the storage tank. As part of the effort to reduce the safety concerns associated with flammable gas in HLW tanks at Hanford, a flammable gas watch list (FGWL) has been established. Inclusion on the FGWL is based on criteria intended to measure the risk associated with the presence of flammable gas. It is important that all high-risk tanks be identified with high confidence so that they may be controlled. Conversely, to minimize operational complexity, the number of tanks on the watchlist should be reduced as near to the true number of flammable risk tanks as the current state of knowledge will support. This report presents an alternative to existing approaches for FGWL screening based on the theory of approximate reasoning (AR) (Zadeh 1976). The AR-based model emulates the inference process used by an expert when asked to make an evaluation. The FGWL model described here was exercised by performing two evaluations. (1) A complete tank evaluation where the entire algorithm is used. This was done for two tanks, U-106 and AW-104. U-106 is a single shell tank with large sludge and saltcake layers. AW-104 is a double shell tank with over one million gallons of supernate. Both of these tanks had failed the screening performed by Hodgson et al. (2) Partial evaluations using a submodule for the predictor likelihood for all of the tanks on the FGWL that had been flagged previously by Whitney (1995)
An approximate-reasoning-based method for screening flammable gas tanks
Energy Technology Data Exchange (ETDEWEB)
Eisenhawer, S.W.; Bott, T.F.; Smith, R.E.
1998-03-01
High-level waste (HLW) produces flammable gases as a result of radiolysis and thermal decomposition of organics. Under certain conditions, these gases can accumulate within the waste for extended periods and then be released quickly into the dome space of the storage tank. As part of the effort to reduce the safety concerns associated with flammable gas in HLW tanks at Hanford, a flammable gas watch list (FGWL) has been established. Inclusion on the FGWL is based on criteria intended to measure the risk associated with the presence of flammable gas. It is important that all high-risk tanks be identified with high confidence so that they may be controlled. Conversely, to minimize operational complexity, the number of tanks on the watchlist should be reduced as near to the true number of flammable risk tanks as the current state of knowledge will support. This report presents an alternative to existing approaches for FGWL screening based on the theory of approximate reasoning (AR) (Zadeh 1976). The AR-based model emulates the inference process used by an expert when asked to make an evaluation. The FGWL model described here was exercised by performing two evaluations. (1) A complete tank evaluation where the entire algorithm is used. This was done for two tanks, U-106 and AW-104. U-106 is a single shell tank with large sludge and saltcake layers. AW-104 is a double shell tank with over one million gallons of supernate. Both of these tanks had failed the screening performed by Hodgson et al. (2) Partial evaluations using a submodule for the predictor likelihood for all of the tanks on the FGWL that had been flagged previously by Whitney (1995).
Multiconditional Approximate Reasoning with Continuous Piecewise Linear Membership Functions
Broek, van den P.M.; Mohammadian, Masoud
1999-01-01
It is shown that, for some intersection and implication functions, an exact and efficient algorithm exists for the computation of inference results in multiconditional approximate reasoning on domains which are finite intervals of the real numbers, when membership functions are restricted to functio
Approximation methods in probability theory
Čekanavičius, Vydas
2016-01-01
This book presents a wide range of well-known and less common methods used for estimating the accuracy of probabilistic approximations, including the Esseen type inversion formulas, the Stein method as well as the methods of convolutions and triangle function. Emphasising the correct usage of the methods presented, each step required for the proofs is examined in detail. As a result, this textbook provides valuable tools for proving approximation theorems. While Approximation Methods in Probability Theory will appeal to everyone interested in limit theorems of probability theory, the book is particularly aimed at graduate students who have completed a standard intermediate course in probability theory. Furthermore, experienced researchers wanting to enlarge their toolkit will also find this book useful.
System reliability assessment with an approximate reasoning model
Energy Technology Data Exchange (ETDEWEB)
Eisenhawer, S.W.; Bott, T.F.; Helm, T.M.; Boerigter, S.T.
1998-12-31
The projected service life of weapons in the US nuclear stockpile will exceed the original design life of their critical components. Interim metrics are needed to describe weapon states for use in simulation models of the nuclear weapons complex. The authors present an approach to this problem based upon the theory of approximate reasoning (AR) that allows meaningful assessments to be made in an environment where reliability models are incomplete. AR models are designed to emulate the inference process used by subject matter experts. The emulation is based upon a formal logic structure that relates evidence about components. This evidence is translated using natural language expressions into linguistic variables that describe membership in fuzzy sets. The authors introduce a metric that measures the acceptability of a weapon to nuclear deterrence planners. Implication rule bases are used to draw a series of forward chaining inferences about the acceptability of components, subsystems and individual weapons. They describe each component in the AR model in some detail and illustrate its behavior with a small example. The integration of the acceptability metric into a prototype model to simulate the weapons complex is also described.
On the integration of reinforcement learning and approximate reasoning for control
Berenji, Hamid R.
1991-01-01
The author discusses the importance of strengthening the knowledge representation characteristic of reinforcement learning techniques using methods such as approximate reasoning. The ARIC (approximate reasoning-based intelligent control) architecture is an example of such a hybrid approach in which the fuzzy control rules are modified (fine-tuned) using reinforcement learning. ARIC also demonstrates that it is possible to start with an approximately correct control knowledge base and learn to refine this knowledge through further experience. On the other hand, techniques such as the TD (temporal difference) algorithm and Q-learning establish stronger theoretical foundations for their use in adaptive control and also in stability analysis of hybrid reinforcement learning and approximate reasoning-based controllers.
Information processing systems, reasoning modules, and reasoning system design methods
Energy Technology Data Exchange (ETDEWEB)
Hohimer, Ryan E.; Greitzer, Frank L.; Hampton, Shawn D.
2015-08-18
Information processing systems, reasoning modules, and reasoning system design methods are described. According to one aspect, an information processing system includes working memory comprising a semantic graph which comprises a plurality of abstractions, wherein the abstractions individually include an individual which is defined according to an ontology and a reasoning system comprising a plurality of reasoning modules which are configured to process different abstractions of the semantic graph, wherein a first of the reasoning modules is configured to process a plurality of abstractions which include individuals of a first classification type of the ontology and a second of the reasoning modules is configured to process a plurality of abstractions which include individuals of a second classification type of the ontology, wherein the first and second classification types are different.
Information processing systems, reasoning modules, and reasoning system design methods
Energy Technology Data Exchange (ETDEWEB)
Hohimer, Ryan E; Greitzer, Frank L; Hampton, Shawn D
2014-03-04
Information processing systems, reasoning modules, and reasoning system design methods are described. According to one aspect, an information processing system includes working memory comprising a semantic graph which comprises a plurality of abstractions, wherein the abstractions individually include an individual which is defined according to an ontology and a reasoning system comprising a plurality of reasoning modules which are configured to process different abstractions of the semantic graph, wherein a first of the reasoning modules is configured to process a plurality of abstractions which include individuals of a first classification type of the ontology and a second of the reasoning modules is configured to process a plurality of abstractions which include individuals of a second classification type of the ontology, wherein the first and second classification types are different.
Information processing systems, reasoning modules, and reasoning system design methods
Energy Technology Data Exchange (ETDEWEB)
Hohimer, Ryan E.; Greitzer, Frank L.; Hampton, Shawn D.
2016-08-23
Information processing systems, reasoning modules, and reasoning system design methods are described. According to one aspect, an information processing system includes working memory comprising a semantic graph which comprises a plurality of abstractions, wherein the abstractions individually include an individual which is defined according to an ontology and a reasoning system comprising a plurality of reasoning modules which are configured to process different abstractions of the semantic graph, wherein a first of the reasoning modules is configured to process a plurality of abstractions which include individuals of a first classification type of the ontology and a second of the reasoning modules is configured to process a plurality of abstractions which include individuals of a second classification type of the ontology, wherein the first and second classification types are different.
Evaluation of high-level waste pretreatment processes with an approximate reasoning model
Energy Technology Data Exchange (ETDEWEB)
Bott, T.F.; Eisenhawer, S.W.; Agnew, S.F.
1999-04-01
The development of an approximate-reasoning (AR)-based model to analyze pretreatment options for high-level waste is presented. AR methods are used to emulate the processes used by experts in arriving at a judgment. In this paper, the authors first consider two specific issues in applying AR to the analysis of pretreatment options. They examine how to combine quantitative and qualitative evidence to infer the acceptability of a process result using the example of cesium content in low-level waste. They then demonstrate the use of simple physical models to structure expert elicitation and to produce inferences consistent with a problem involving waste particle size effects.
Scientific Facts and Methods in Public Reason
DEFF Research Database (Denmark)
Jønch-Clausen, Karin; Kappel, Klemens
2016-01-01
Should scientific facts and methods have an epistemically privileged status in public reason? In Rawls’s public reason account he asserts what we will label the Scientific Standard Stricture: citizens engaged in public reason must be guided by non-controversial scientific methods, and public reason...... must be in line with non-controversial scientific conclusions. The Scientific Standard Stricture is meant to fulfill important tasks such as enabling the determinateness and publicity of the public reason framework. However, Rawls leaves us without elucidation with regard to when science...
A New Method for Reasoning about Action
Institute of Scientific and Technical Information of China (English)
杨杰
1996-01-01
Reasoning about action is an important aspect of common sense reasoning and planning.It gives rise to three classical problems:the frame problem,the qualification problem and the ramification problem.Existing approaches cannot deal with these problems efficiently.This paper presents a new method which uses the stratified ATMS for reasoning about action to overcome the limitations of these approaches.
Approximations in the PE-method
DEFF Research Database (Denmark)
Arranz, Marta Galindo
1996-01-01
Two differenct sources of errors may occur in the implementation of the PE methods; a phase error introduced in the approximation of a pseudo-differential operator and an amplitude error generated from the starting field. First, the inherent phase errors introduced in the solution are analyzed...
Research of Approximate Reasoning in Semantic Web%语义Web近似推理研究
Institute of Scientific and Technical Information of China (English)
廖先旭; 黄佳进
2011-01-01
随着语义Web本体技术的快速发展和近似推理技术的应用，语义Web近似推理满足了快速有效地搜索有用的信息和知识的需求。本文主要从语义Web近似推理的难点介绍了近年来关于语义web近似推理的研究，并在最后对语义web近似推理研究的发展趋势做了总结。%With the fast development of ontology technology for Semantic Web and the application of approximate reasoning, approximate reasoning on the Semantic Web can satisfy the demand of finding useful information and knowledge fast and efficiently. This paper introduces approximate reasoning on the Semantic Web research in recent years from its key problems and the research trends of approximate reasoning on Semantic Web.
Generalized If ... Then...Else Inference Rules with Linguistic Modifiers for Approximate Reasoning
Directory of Open Access Journals (Sweden)
Le Anh Phuong
2012-11-01
Full Text Available In this paper, based on the our previous researchs about generalized modus ponens with linguistic modifiers for If...Then rules, we propose generalized If...Then...Else inference rules with linguistic modifiers in linguistic many-valued logic framework with using hedge moving rules for approximate reasoning.
Energy Technology Data Exchange (ETDEWEB)
Darby, John L.
2007-03-01
LinguisticBelief is a Java computer code that evaluates combinations of linguistic variables using an approximate reasoning rule base. Each variable is comprised of fuzzy sets, and a rule base describes the reasoning on combinations of variables fuzzy sets. Uncertainty is considered and propagated through the rule base using the belief/plausibility measure. The mathematics of fuzzy sets, approximate reasoning, and belief/ plausibility are complex. Without an automated tool, this complexity precludes their application to all but the simplest of problems. LinguisticBelief automates the use of these techniques, allowing complex problems to be evaluated easily. LinguisticBelief can be used free of charge on any Windows XP machine. This report documents the use and structure of the LinguisticBelief code, and the deployment package for installation client machines.
On the approximate zero of Newton method
Institute of Scientific and Technical Information of China (English)
黄正达
2003-01-01
A judgment criterion to guarantee a point to be a Chen' s approximate zero of Newton method for solving nonlinear equation is sought by dominating sequence techniques. The criterion is based on the fact that the dominating function may have only one simple positive zero, assuming that the operator is weak Lipschitz continuous, which is much more relaxed and can be checked much more easily than Lipschitz continuous in practice. It is demonstrated that a Chen' s approximate zero may not be a Smale' s approximate zero. The error estimate obtained indicated the convergent order when we use |f(x) | < ε to stop computation in software.The result can also be applied for solving partial derivative and integration equations.
Truth Degrees Theory and Approximate Reasoning in 3-Valued Propositional Pre-Rough Logic
Directory of Open Access Journals (Sweden)
Yingcang Ma
2013-01-01
Full Text Available By means of the function induced by a logical formula A, the concept of truth degree of the logical formula A is introduced in the 3-valued pre-rough logic in this paper. Moreover, similarity degrees among formulas are proposed and a pseudometric is defined on the set of formulas, and hence a possible framework suitable for developing approximate reasoning theory in 3-value logic pre-rough logic is established.
Approximate syllogistic reasoning: a contribution to inference patterns and use cases
Pereira-Fariña, Martín
2014-01-01
In this thesis two models of syllogistic reasoning for dealing with arguments that involve fuzzy quantified statements and approximate chaining are proposed. The modeling of quantified statements is based on the Theory of Generalized Quantifiers, which allows us to manage different kind of quantifiers simultaneously, and the inference process is interpreted in terms of a mathematical optimization problem, which allows us to deal with more arguments that standard deductive ones. For the case o...
Study of quarkonium spectroscopy through the approximated variational method
International Nuclear Information System (INIS)
The spectroscopy of the qq sup(-) bound states in a non-relativistic approximation using a approximate variational method is studied. Because of its similarity to positronium, a wave function of the hidrogen atom, is used. The 'coulomb-logaritmic-linear' was the potential used to described it. The fitting is done, and relevant coupling constant due to a logaritmic piece is found. All states described in this way furnishes v2 3P are reasonably explained and it no occurs with the mass diference between psi and eta sub(c). (Author)
Approximate Methods for State-Space Models
Koyama, Shinsuke; Shalizi, Cosma Rohilla; Kass, Robert E; 10.1198/jasa.2009.tm08326
2010-01-01
State-space models provide an important body of techniques for analyzing time-series, but their use requires estimating unobserved states. The optimal estimate of the state is its conditional expectation given the observation histories, and computing this expectation is hard when there are nonlinearities. Existing filtering methods, including sequential Monte Carlo, tend to be either inaccurate or slow. In this paper, we study a nonlinear filter for nonlinear/non-Gaussian state-space models, which uses Laplace's method, an asymptotic series expansion, to approximate the state's conditional mean and variance, together with a Gaussian conditional distribution. This {\\em Laplace-Gaussian filter} (LGF) gives fast, recursive, deterministic state estimates, with an error which is set by the stochastic characteristics of the model and is, we show, stable over time. We illustrate the estimation ability of the LGF by applying it to the problem of neural decoding and compare it to sequential Monte Carlo both in simulat...
Reverse triple I method of fuzzy reasoning
Institute of Scientific and Technical Information of China (English)
宋士吉; 吴澄
2002-01-01
A theory of reverse triple I method with sustention degree is presented by using the implication operator R0 in every step of the fuzzy reasoning. Its computation formulas of supremum for fuzzy modus ponens and infimum for fuzzy modus tollens are given respectively. Moreover, through the generalization of this problem, the corresponding formulas of ?-reverse triple I method with sustention degree are also obtained. In addition, the theory of reverse triple I method with restriction degree is proposed as well by using the operator R0, and the computation formulas of infimum for fuzzy modus ponens and supremum for fuzzy modus tollens are shown.
Approximating methods for intractable probabilistic models: Applications in neuroscience
DEFF Research Database (Denmark)
Højen-Sørensen, Pedro
2002-01-01
field methods. The thesis provides a brief introduction to the basic methodology of learning and inference in graphical models as well as a short review of the various types of mean field approximations which recently have been shown to be efficient for carrying out approximate inference in intractable...... an adaptive version of the Thouless, Anderson and Palmer (TAP) mean field approach which is due to Opper and Winther. To illustrate the methodology on a real world problem, an explorative analysis of a functional magnetic resonance imaging (fMRI) dataset from a visual activation study is carried out using ICA...... with binary sources. It is shown this approach, which is computationally efficient, infers reasonable brain activation functions. Finally, we outline various ways of carrying out approximate message passing in probabilistic models for which marginalization over some of the clique variables is intractable....
Hoebel, Louis J.
1993-01-01
The problem of plan generation (PG) and the problem of plan execution monitoring (PEM), including updating, queries, and resource-bounded replanning, have different reasoning and representation requirements. PEM requires the integration of qualitative and quantitative information. PEM is the receiving of data about the world in which a plan or agent is executing. The problem is to quickly determine the relevance of the data, the consistency of the data with respect to the expected effects, and if execution should continue. Only spatial and temporal aspects of the plan are addressed for relevance in this work. Current temporal reasoning systems are deficient in computational aspects or expressiveness. This work presents a hybrid qualitative and quantitative system that is fully expressive in its assertion language while offering certain computational efficiencies. In order to proceed, methods incorporating approximate reasoning using hierarchies, notions of locality, constraint expansion, and absolute parameters need be used and are shown to be useful for the anytime nature of PEM.
An approximate method of analysis for notched unidirectional composites
Zweben, C.
1974-01-01
An approximate method is proposed for the analysis of unidirectional, filamentary composite materials having slit notches perpendicular to the fibers and subjected to tension parallel to the fibers. The approach is based on an engineering model which incorporates important effects of material heterogeneity by considering average extensional stresses in the fibers and average shear stresses in the matrix. Effects of interfacial failure and matrix plasticity at the root of the notch are considered. Predictions of the analysis are in reasonably good agreement with previous analytical models and experimental data for graphite/epoxy.
Methods of Fourier analysis and approximation theory
Tikhonov, Sergey
2016-01-01
Different facets of interplay between harmonic analysis and approximation theory are covered in this volume. The topics included are Fourier analysis, function spaces, optimization theory, partial differential equations, and their links to modern developments in the approximation theory. The articles of this collection were originated from two events. The first event took place during the 9th ISAAC Congress in Krakow, Poland, 5th-9th August 2013, at the section “Approximation Theory and Fourier Analysis”. The second event was the conference on Fourier Analysis and Approximation Theory in the Centre de Recerca Matemàtica (CRM), Barcelona, during 4th-8th November 2013, organized by the editors of this volume. All articles selected to be part of this collection were carefully reviewed.
Approximate reasoning-based learning and control for proximity operations and docking in space
Berenji, Hamid R.; Jani, Yashvant; Lea, Robert N.
1991-01-01
A recently proposed hybrid-neutral-network and fuzzy-logic-control architecture is applied to a fuzzy logic controller developed for attitude control of the Space Shuttle. A model using reinforcement learning and learning from past experience for fine-tuning its knowledge base is proposed. Two main components of this approximate reasoning-based intelligent control (ARIC) model - an action-state evaluation network and action selection network are described as well as the Space Shuttle attitude controller. An ARIC model for the controller is presented, and it is noted that the input layer in each network includes three nodes representing the angle error, angle error rate, and bias node. Preliminary results indicate that the controller can hold the pitch rate within its desired deadband and starts to use the jets at about 500 sec in the run.
Energy Technology Data Exchange (ETDEWEB)
Pin, F.G.
1993-11-01
Outdoor sensor-based operation of autonomous robots has revealed to be an extremely challenging problem, mainly because of the difficulties encountered when attempting to represent the many uncertainties which are always present in the real world. These uncertainties are primarily due to sensor imprecisions and unpredictability of the environment, i.e., lack of full knowledge of the environment characteristics and dynamics. Two basic principles, or philosophies, and their associated methodologies are proposed in an attempt to remedy some of these difficulties. The first principle is based on the concept of ``minimal model`` for accomplishing given tasks and proposes to utilize only the minimum level of information and precision necessary to accomplish elemental functions of complex tasks. This approach diverges completely from the direction taken by most artificial vision studies which conventionally call for crisp and detailed analysis of every available component in the perception data. The paper will first review the basic concepts of this approach and will discuss its pragmatic feasibility when embodied in a behaviorist framework. The second principle which is proposed deals with implicit representation of uncertainties using Fuzzy Set Theory-based approximations and approximate reasoning, rather than explicit (crisp) representation through calculation and conventional propagation techniques. A framework which merges these principles and approaches is presented, and its application to the problem of sensor-based outdoor navigation of a mobile robot is discussed. Results of navigation experiments with a real car in actual outdoor environments are also discussed to illustrate the feasibility of the overall concept.
International Nuclear Information System (INIS)
Outdoor sensor-based operation of autonomous robots has revealed to be an extremely challenging problem, mainly because of the difficulties encountered when attempting to represent the many uncertainties which are always present in the real world. These uncertainties are primarily due to sensor imprecisions and unpredictability of the environment, i.e., lack of full knowledge of the environment characteristics and dynamics. Two basic principles, or philosophies, and their associated methodologies are proposed in an attempt to remedy some of these difficulties. The first principle is based on the concept of ''minimal model'' for accomplishing given tasks and proposes to utilize only the minimum level of information and precision necessary to accomplish elemental functions of complex tasks. This approach diverges completely from the direction taken by most artificial vision studies which conventionally call for crisp and detailed analysis of every available component in the perception data. The paper will first review the basic concepts of this approach and will discuss its pragmatic feasibility when embodied in a behaviorist framework. The second principle which is proposed deals with implicit representation of uncertainties using Fuzzy Set Theory-based approximations and approximate reasoning, rather than explicit (crisp) representation through calculation and conventional propagation techniques. A framework which merges these principles and approaches is presented, and its application to the problem of sensor-based outdoor navigation of a mobile robot is discussed. Results of navigation experiments with a real car in actual outdoor environments are also discussed to illustrate the feasibility of the overall concept
Shape theory categorical methods of approximation
Cordier, J M
2008-01-01
This in-depth treatment uses shape theory as a ""case study"" to illustrate situations common to many areas of mathematics, including the use of archetypal models as a basis for systems of approximations. It offers students a unified and consolidated presentation of extensive research from category theory, shape theory, and the study of topological algebras.A short introduction to geometric shape explains specifics of the construction of the shape category and relates it to an abstract definition of shape theory. Upon returning to the geometric base, the text considers simplical complexes and
Prioritizing the purchase of spare parts using an approximate reasoning models.
Energy Technology Data Exchange (ETDEWEB)
Eisenhawer, S. W. (Stephen W.); Bott, T. F. (Terrence F.); Jackson, J. W. (Joseph W.)
2001-01-01
The complexity of a spare parts prioritization model should be consonant with the amount and quality of data available to populate it. When production processes are new and the reliability database is sparse and represents primarily expert knowledge, an approximate reasoning (AR) based model is appropriate. AR models are designed to emulate the inferential processes used by experts in making judgments. We have designed and tested such a model for the planned component production process for nuclear weapons at Los Alamos National Laboratory. The model successfully represents the experts knowledge concerning the frequency and consequences of a part failure. The use of linguistic variables provides an adaptable format for eliciting this knowledge and providing a consistent brisis for valuing the effect on production of different parts. Ranking the parts for inclusion in a spare parts inventory is a straightforward transformation of the AR output. The basis for this ranking is directly traceable to the elicitation results. AR-based models are well-suited to prioritization problems with these characteristics.
Augmenting Ordinal Methods of Attribute Weight Approximation
DEFF Research Database (Denmark)
Daneilson, Mats; Ekenberg, Love; He, Ying
2014-01-01
Multicriteria decision aid (MCDA) methods have been around for quite some time. However, the elicitation of preference information in MCDA processes and the lack of supporting practical means are problematic in real-life applications. Various proposals have been made for how to eliminate some...... of the obstacles and methods for introducing so-called surrogate weights have proliferated in the form of ordinal ranking methods for criteria weights. Considering the decision quality, one main problem is that the input information allowed in ordinal methods is sometimes too restricted. At the same time, decision...... makers often possess more background information, for example, regarding the relative strengths of the criteria, and might want to use that. We propose combined methods for facilitating the elicitation process and show how this provides a way to use partial information from the strength of preference...
Reasons and Methods to Learn the Management
Li, Hongxin; Ding, Mengchun
2010-01-01
Reasons for learning the management include (1) perfecting the knowledge structure, (2) the management is the base of all organizations, (3) one person may be the manager or the managed person, (4) the management is absolutely not simple knowledge, and (5) the learning of the theoretical knowledge of the management can not be replaced by the…
An Analysis of General Fuzzy Logic and Fuzzy Reasoning Method
Il, Kwak Son
2016-01-01
In this article, we describe the fuzzy logic, fuzzy language and algorithms as the basis of fuzzy reasoning, one of the intelligent information processing method, and then describe the general fuzzy reasoning method.
PERSONNEL DEMOTIVATING: THE REASONS, FACTORS, ELIMINATION METHODS
Kuznetsova Ekaterina Andreevna
2012-01-01
The motivation of the personnel in any economic conditions remains a leading link in an enterprise control system. At creation of system of motivation tracking of extent of its impact on productivity of work of the personnel is important. The boomerang effect which is shown in a demotivating of separate groups of the personnel is often observed. In article features of manifestation of demotivating factors at various stages of work of the personnel are analyzed, the circle of the reasons bring...
A working-set framework for sequential convex approximation methods
DEFF Research Database (Denmark)
Stolpe, Mathias
2008-01-01
We present an active-set algorithmic framework intended as an extension to existing implementations of sequential convex approximation methods for solving nonlinear inequality constrained programs. The framework is independent of the choice of approximations and the stabilization technique used...
Institute of Scientific and Technical Information of China (English)
Zhang Zheng-Jie; Wang Ke-Lin; Qin Gan
2005-01-01
By a model of atwo-level particle coupled with boson field, we made it clear that an evolution problem can be solved beyond the rotating wave approximation. We have applied the coherent approximation method, which had been proved to be effective in dealing with stationary state problems of polaron, to the evolution problem of the system mentioned above. The results obtained showed that the coherent approximation method is effective to treat the evolution problem,and, in general cases, the non-rotating wave terms in Hamiltonian should not be ignored. Our results may provide a deep physical insight for further experiments to test the effects of non-rotating wave terms.
Institute of Scientific and Technical Information of China (English)
WANG Guojun; CHIN K. S.; DANG C.Y.
2005-01-01
The concepts of metric R0-algebra and Hilbert cube of type R0 are introduced.A unified approximate reasoning theory in propositional caculus system L* and predicate calculus system K* is established semantically as well as syntactically, and a unified complete theorem is obtained.
High order source approximation for the EFEN method
International Nuclear Information System (INIS)
The flat source approximation in one dimensional Exponential Function Expansion Nodal (EFEN) method is extended to a high order polynomial approximation while maintaining the simplicity of the nodal response matrix. By applying the new method to a one dimensional PWR pin-by-pin problem, it has been observed that quadratic source approximation is good enough for PWR pin-by-pin calculation, while the flat source approximation causes about 5% of relative error to the thermal flux. By applying the new method to a one dimensional assembly homogenized problem, it has been found that the EFEN method with cubic source approximation can be employed to handle PWR core diffusion problems. Numerical results suggest the optimization of source approximation order for different energy groups and different spacial locations to achieve more accurate results with less computing effort. (author)
Approximations of continuous Newton's method: An extension of Cayley's problem
Directory of Open Access Journals (Sweden)
Jon Jacobsen
2007-02-01
Full Text Available Continuous Newton's Method refers to a certain dynamical system whose associated flow generically tends to the roots of a given polynomial. An Euler approximation of this system, with step size $h=1$, yields the discrete Newton's method algorithm for finding roots. In this note we contrast Euler approximations with several different approximations of the continuous ODE system and, using computer experiments, consider their impact on the associated fractal basin boundaries of the roots.
Nonlinear ordinary differential equations analytical approximation and numerical methods
Hermann, Martin
2016-01-01
The book discusses the solutions to nonlinear ordinary differential equations (ODEs) using analytical and numerical approximation methods. Recently, analytical approximation methods have been largely used in solving linear and nonlinear lower-order ODEs. It also discusses using these methods to solve some strong nonlinear ODEs. There are two chapters devoted to solving nonlinear ODEs using numerical methods, as in practice high-dimensional systems of nonlinear ODEs that cannot be solved by analytical approximate methods are common. Moreover, it studies analytical and numerical techniques for the treatment of parameter-depending ODEs. The book explains various methods for solving nonlinear-oscillator and structural-system problems, including the energy balance method, harmonic balance method, amplitude frequency formulation, variational iteration method, homotopy perturbation method, iteration perturbation method, homotopy analysis method, simple and multiple shooting method, and the nonlinear stabilized march...
Approximate inverse preconditioning of iterative methods for nonsymmetric linear systems
Energy Technology Data Exchange (ETDEWEB)
Benzi, M. [Universita di Bologna (Italy); Tuma, M. [Inst. of Computer Sciences, Prague (Czech Republic)
1996-12-31
A method for computing an incomplete factorization of the inverse of a nonsymmetric matrix A is presented. The resulting factorized sparse approximate inverse is used as a preconditioner in the iterative solution of Ax = b by Krylov subspace methods.
Energy of Bardeen Model Using Approximate Symmetry Method
Sharif, M.; Waheed, Saira
2010-01-01
In this paper, we investigate the energy problem in general relativity using approximate Lie symmetry methods for differential equations. This procedure is applied to Bardeen model (the regular black hole solution). Here we are forced to evaluate the third-order approximate symmetries of the orbital and geodesic equations. It is shown that energy must be re-scaled by some factor in the third-order approximation. We discuss the insights of this re-scaling factor.
An Approximation Method of NURBS Curves in NC Machining
Institute of Scientific and Technical Information of China (English)
YUE Ying; HAN Qingyao; WANG Zhangqi
2006-01-01
An algorithm for approximating arbitrary NURBS curve with straight line is presented. Firstly, NURBS curve is acquired according to data points on the curve. Secondly, Approximating arbitrary NURBS curve is based on dichotomy. The resulting straight line approaches to the original curve with relatively fewer segments within the required tolerance. The example shows that the algorithm is simple and its approximation precision is high. The method is most useful in numerical control to drive the cutter along straight line or circular paths.
Numerical Stability and Convergence of Approximate Methods for Conservation Laws
Galkin, V. A.
We present the new approach to background of approximate methods convergence based on functional solutions theory for conservation laws. The applications to physical kinetics, gas and fluid dynamics are considered.
Calculating resonance positions and widths using the Siegert approximation method
Rapedius, Kevin
2011-01-01
Here we present complex resonance states (or Siegert states), that describe the tunneling decay of a trapped quantum particle, from an intuitive point of view which naturally leads to the easily applicable Siegert approximation method that can be used for analytical and numerical calculations of complex resonances of both the linear and nonlinear Schr\\"odinger equation. Our approach thus complements other treatments of the subject that mostly focus on methods based on continuation in the complex plane or on semiclassical approximations.
A double power series method for approximating cosmological perturbations
Wren, Andrew J
2016-01-01
We introduce a double power series method for finding approximate analytical solutions for systems of differential equations commonly found in cosmological perturbation theory. The method was set out, in a non-cosmological context, by Feshchenko, Shkil' and Nikolenko (FSN) in 1966, and is applicable to cases where perturbations are on sub-horizon scales. The FSN method is essentially an extension of the well known Wentzel-Kramers-Brillouin (WKB) method for finding approximate analytical solutions for ordinary differential equations. The FSN method is well suited for solving systems of linear second order ordinary differential equations, that also depend on a small parameter, which here we take to be the inverse wave-number. We use the FSN method to find new approximate oscillating solutions in linear order cosmological perturbation theory for a flat radiation-matter universe. Together with this model's well known growing and decaying M\\'esz\\'aros solutions, these oscillating modes provide a complete set of su...
A Semantic Retrieval Method Based on the Fuzzy Reasoning
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
This paper gives a semantic fuzzy retrieval method of multimedia object,discusses the principle of fuzzy semantic retrieval technique,presents a fuzzy reasoning mechanism based on the knowledge base,and designs the relevant reasoning algorithms.Researchful results have innovative significance.
Dual methods and approximation concepts in structural synthesis
Fleury, C.; Schmit, L. A., Jr.
1980-01-01
Approximation concepts and dual method algorithms are combined to create a method for minimum weight design of structural systems. Approximation concepts convert the basic mathematical programming statement of the structural synthesis problem into a sequence of explicit primal problems of separable form. These problems are solved by constructing explicit dual functions, which are maximized subject to nonnegativity constraints on the dual variables. It is shown that the joining together of approximation concepts and dual methods can be viewed as a generalized optimality criteria approach. The dual method is successfully extended to deal with pure discrete and mixed continuous-discrete design variable problems. The power of the method presented is illustrated with numerical results for example problems, including a metallic swept wing and a thin delta wing with fiber composite skins.
An approximate method to acoustic radiation problems: element radiation superposition method
Institute of Scientific and Technical Information of China (English)
wANG Bin; TANG weilin; FAN Jun
2008-01-01
An approximate method is brought forward to predict the acoustic pressure based on the surface velocity.It is named Element Radiation Superposition Method(ERSM).The study finds that each element in Acoustic Transfer Vector(ATV)equals the acoustic pressure radiated by the corresponding surface element vibrating in unit velocity and other surface elements keep still.that is the acoustic pressure radiated by the corresponding baffled pistonvibrating in unit velocity.So,it utilizes the acoustic pressure radiated by a baffled piston to establish the transfer relationship between the surfaEe velocity and the acoustic pressure.The total acoustic pressure is obtained through summing up the products of the surface velocity and the transfer quantity.It adopts the regular baffle to fit the actual baffle in order to calculate the acoustic pressure radiated by the baffled piston.This approximate method has larger advantage in calculating speed and memory space than Boundary Element Method.Numerical simulations show that this approximate method is reasonable and feasible.
Approximating methods for intractable probabilistic models: Applications in neuroscience
Højen-Sørensen, Pedro; Hansen, Lars Kai; Rasmussen, Carl Edward; Larsen, Jan
2002-01-01
This thesis investigates various methods for carrying out approximate inference in intractable probabilistic models. By capturing the relationships between random variables, the framework of graphical models hints at which sets of random variables pose a problem to the inferential step. The approximating techniques used in this thesis originate from the field of statistical physics which for decades has been facing the same type of intractable computations when analyzing large systems of inte...
Approximate methods in gamma-ray skyshine calculations
International Nuclear Information System (INIS)
An approximate computational method for gamma-ray skyshine calculations is described. The method is suitable for a source collimated uniformly about the vertical and accounts for uniform overhead concrete shielding above the source. Results of calculations are compared to measurements as well as results of other calculations
Higher-order Chebyshev rational approximation method (CRAM)
International Nuclear Information System (INIS)
The burnup equations can in principle be solved by computing the exponential of the burnup matrix. However, due to the difficult numerical characteristics of burnup matrices, the problem is extremely stiff, and the matrix exponential solution was long considered infeasible for an entire burnup system containing over a thousand nuclides. After discovering that the eigenvalues of burnup matrices are generally confined to a region near the negative real axis, the Chebyshev rational approximation method (CRAM) was introduced as a novel method to solve the burnup equations. It can be characterized as the best rational function on the negative real axis and it has been shown to be capable of simultaneously solving an entire burnup system both accurately and efficiently. The main difficulty in using CRAM for computing the matrix exponential is determining the coefficients of the rational function for a given approximation order. Some polynomial CRAM coefficients have been published in 1984, and based on these literature values, CRAM approximations up to the order 16 have been thus far applied in burnup calculations. The topic of this paper is the computation of CRAM approximations and their application to burnup equations. A Remez-type method utilizing the equioscillation property of best approximations is used to construct the CRAM approximants for approximation orders 1,. . . , 50. Numerical results are presented for a large burnup system and for a decay system. It is demonstrated that higher-order CRAM can be used to accurately solve the burnup equations even with time steps of the order of millions of years. (author)
Complex method for approximated solutions to Born-Infeld equation
Ferraro, Rafael
2015-01-01
We display the method to solve the Born-Infeld equation in the complex plane. As the exact solution is obtained in an implicit form, we turn it into an explicit form by means of a perturbative procedure which takes care of secular behaviors common to this kind of approximations. We apply the method to build solutions to Born-Infeld electrodynamics. In particular, we study BI electromagnetic waves at interfaces, with the aim of searching for effects susceptible of experimental detection.
An approximation concepts method for space frame synthesis
Mills-Curran, W. C.; Lust, R. V.; Schmit, L. A.
1982-01-01
A method is presented for the minimum mass design of three dimensional space frames constructed of thin walled rectangular cross-section members. Constraints on nodal displacements and rotations, material stress, local buckling, and cross sectional dimensions are included. A high quality separable approximate problem is formed in terms of the reciprocals of the four section properties of the frame element cross section, replacing all implicit functions with simplified explicit relations. The cross sectional dimensions are efficiently calculated without using multilevel techniques. Several test problems are solved, demonstrating that a series of approximate problem solutions converge rapidly to an optimal design.
Children's Expression of Negative Affect: Reasons and Methods.
Zeman, Janice; Shipman, Kimberly
1996-01-01
Examines the influence of socialization figures (parents, friends), emotion type (anger, sadness, physical pain), age, and gender on 66 second-grade and 71 fifth-grade children's reasons for and methods of affect expression. Found that girls reported using verbal means to communicate emotion, whereas boys cited mildly aggressive methods. (MDM)
Epistemological Development and Judgments and Reasoning about Teaching Methods
Spence, Sarah; Helwig, Charles C.
2013-01-01
Children's, adolescents', and adults' (N = 96 7-8, 10-11, and 13-14-year-olds and university students) epistemological development and its relation to judgments and reasoning about teaching methods was examined. The domain (scientific or moral), nature of the topic (controversial or noncontroversial), and teaching method (direct…
Interfacing Relativistic and Nonrelativistic Methods: A Systematic Sequence of Approximations
Dyall, Ken; Langhoff, Stephen R. (Technical Monitor)
1997-01-01
A systematic sequence of approximations for the introduction of relativistic effects into nonrelativistic molecular finite-basis set calculations is described. The theoretical basis for the approximations is the normalized elimination of the small component (ESC) within the matrix representation of the modified Dirac equation. The key features of the normalized method are the retention of the relativistic metric and the ability to define a single matrix U relating the pseudo-large and large component coefficient matrices. This matrix is used to define a modified set of one- and two-electron integrals which have the same appearance as the integrals of the Breit-Pauli Hamiltonian. The first approximation fixes the ratios of the large and pseudo-large components to their atomic values, producing an expansion in atomic 4-spinors. The second approximation defines a local fine-structure constant on each atomic centre, which has the physical value for centres considered to be relativistic and zero for nonrelativistic centres. In the latter case, the 4-spinors are the positive-energy kinetic al ly-balanced solutions of the Levy-Leblond equation, and the integrals involving pseudo-large component basis functions on these centres, are set to zero. Some results are presented for test systems to illustrate the various approximations.
Approximation methods for the partition functions of anharmonic systems
Energy Technology Data Exchange (ETDEWEB)
Lew, P.; Ishida, T.
1979-07-01
The analytical approximations for the classical, quantum mechanical and reduced partition functions of the diatomic molecule oscillating internally under the influence of the Morse potential have been derived and their convergences have been tested numerically. This successful analytical method is used in the treatment of anharmonic systems. Using Schwinger perturbation method in the framework of second quantization formulism, the reduced partition function of polyatomic systems can be put into an expression which consists separately of contributions from the harmonic terms, Morse potential correction terms and interaction terms due to the off-diagonal potential coefficients. The calculated results of the reduced partition function from the approximation method on the 2-D and 3-D model systems agree well with the numerical exact calculations.
Approximation methods for the partition functions of anharmonic systems
International Nuclear Information System (INIS)
The analytical approximations for the classical, quantum mechanical and reduced partition functions of the diatomic molecule oscillating internally under the influence of the Morse potential have been derived and their convergences have been tested numerically. This successful analytical method is used in the treatment of anharmonic systems. Using Schwinger perturbation method in the framework of second quantization formulism, the reduced partition function of polyatomic systems can be put into an expression which consists separately of contributions from the harmonic terms, Morse potential correction terms and interaction terms due to the off-diagonal potential coefficients. The calculated results of the reduced partition function from the approximation method on the 2-D and 3-D model systems agree well with the numerical exact calculations
Parallel iterative solvers and preconditioners using approximate hierarchical methods
Energy Technology Data Exchange (ETDEWEB)
Grama, A.; Kumar, V.; Sameh, A. [Univ. of Minnesota, Minneapolis, MN (United States)
1996-12-31
In this paper, we report results of the performance, convergence, and accuracy of a parallel GMRES solver for Boundary Element Methods. The solver uses a hierarchical approximate matrix-vector product based on a hybrid Barnes-Hut / Fast Multipole Method. We study the impact of various accuracy parameters on the convergence and show that with minimal loss in accuracy, our solver yields significant speedups. We demonstrate the excellent parallel efficiency and scalability of our solver. The combined speedups from approximation and parallelism represent an improvement of several orders in solution time. We also develop fast and paralellizable preconditioners for this problem. We report on the performance of an inner-outer scheme and a preconditioner based on truncated Green`s function. Experimental results on a 256 processor Cray T3D are presented.
Approximation methods for efficient learning of Bayesian networks
Riggelsen, C
2008-01-01
This publication offers and investigates efficient Monte Carlo simulation methods in order to realize a Bayesian approach to approximate learning of Bayesian networks from both complete and incomplete data. For large amounts of incomplete data when Monte Carlo methods are inefficient, approximations are implemented, such that learning remains feasible, albeit non-Bayesian. The topics discussed are: basic concepts about probabilities, graph theory and conditional independence; Bayesian network learning from data; Monte Carlo simulation techniques; and, the concept of incomplete data. In order to provide a coherent treatment of matters, thereby helping the reader to gain a thorough understanding of the whole concept of learning Bayesian networks from (in)complete data, this publication combines in a clarifying way all the issues presented in the papers with previously unpublished work.
Optimization in engineering sciences approximate and metaheuristic methods
Stefanoiu, Dan; Popescu, Dumitru; Filip, Florin Gheorghe; El Kamel, Abdelkader
2014-01-01
The purpose of this book is to present the main metaheuristics and approximate and stochastic methods for optimization of complex systems in Engineering Sciences. It has been written within the framework of the European Union project ERRIC (Empowering Romanian Research on Intelligent Information Technologies), which is funded by the EU's FP7 Research Potential program and has been developed in co-operation between French and Romanian teaching researchers. Through the principles of various proposed algorithms (with additional references) this book allows the reader to explore various methods o
Simple Methods to Approximate CPC Shape to Preserve Collection Efficiency
Directory of Open Access Journals (Sweden)
David Jafrancesco
2012-01-01
Full Text Available The compound parabolic concentrator (CPC is the most efficient reflective geometry to collect light to an exit port. Anyway, to allow its actual use in solar plants or photovoltaic concentration systems, a tradeoff between system efficiency and cost reduction, the two key issues for sunlight exploitation, must be found. In this work, we analyze various methods to model an approximated CPC aimed to be simpler and more cost-effective than the ideal one, as well as to preserve the system efficiency. The manufacturing easiness arises from the use of truncated conic surfaces only, which can be realized by cheap machining techniques. We compare different configurations on the basis of their collection efficiency, evaluated by means of nonsequential ray-tracing software. Moreover, due to the fact that some configurations are beam dependent and for a closer approximation of a real case, the input beam is simulated as nonsymmetric, with a nonconstant irradiance on the CPC internal surface.
A Surface Approximation Method for Image and Video Correspondences.
Huang, Jingwei; Wang, Bin; Wang, Wenping; Sen, Pradeep
2015-12-01
Although finding correspondences between similar images is an important problem in image processing, the existing algorithms cannot find accurate and dense correspondences in images with significant changes in lighting/transformation or with the non-rigid objects. This paper proposes a novel method for finding accurate and dense correspondences between images even in these difficult situations. Starting with the non-rigid dense correspondence algorithm [1] to generate an initial correspondence map, we propose a new geometric filter that uses cubic B-Spline surfaces to approximate the correspondence mapping functions for shared objects in both images, thereby eliminating outliers and noise. We then propose an iterative algorithm which enlarges the region containing valid correspondences. Compared with the existing methods, our method is more robust to significant changes in lighting, color, or viewpoint. Furthermore, we demonstrate how to extend our surface approximation method to video editing by first generating a reliable correspondence map between a given source frame and each frame of a video. The user can then edit the source frame, and the changes are automatically propagated through the entire video using the correspondence map. To evaluate our approach, we examine applications of unsupervised image recognition and video texture editing, and show that our algorithm produces better results than those from state-of-the-art approaches. PMID:26241974
Sparse matrix approximation method for an active optical control system
Murphy, Timothy P.; Lyon, Richard G.; Dorband, John E.; Hollis, Jan M.
2001-12-01
We develop a sparse matrix approximation method to decompose a wave front into a basis set of actuator influence functions for an active optical system consisting of a deformable mirror and a segmented primary mirror. The wave front used is constructed by Zernike polynomials to simulate the output of a phase-retrieval algorithm. Results of a Monte Carlo simulation of the optical control loop are compared with the standard, nonsparse approach in terms of accuracy and precision, as well as computational speed and memory. The sparse matrix approximation method can yield more than a 50-fold increase in the speed and a 20-fold-reduction in matrix size and a commensurate decrease in required memory, with less than 10% degradation in solution accuracy. Our method is also shown to be better than when elements are selected for the sparse matrix on a magnitude basis alone. We show that the method developed is a viable alternative to use of the full control matrix in a phase-retrieval-based active optical control system.
An Approximate Analytical Method of the Nonlinear Vibroacoustic Coupling System
Directory of Open Access Journals (Sweden)
Qizheng Zhou
2014-01-01
Full Text Available An approximate analytical method of the nonlinear vibroacoustic coupling system is proposed for the first time. Taking the Duffing oscillator-plate-medium system as an example, the nonlinear vibroacoustic coupling equations are developed using variational principle. The two major difficulties which lie in solving the coupling equations are the uncertain motion of the oscillator and the surface acoustic pressure on the plate, a system for which the fluid-structure coupling cannot be neglected. Based on the incremental harmonic balance (IHB method, the motion of the oscillator is expressed in the form of the Fourier series, and then the modal expression method and the incoherent assumption are employed to discretize the displacement and the surface pressure of the plate. Then the approximate analytical solution is given by the IHB method. The characteristics of acoustic radiation and surface quadratic velocity of the plate, the nonlinear characteristics of oscillator, and the influence of the excitation frequency and the nonlinear stiffness on the results are investigated by the numerical simulation. The results show that the excitation at the frequency close to the natural frequency of the oscillator can produce a significant response of the third-harmonic generation which determines the vibroacoustic characteristics of the plate.
An Adaptive Derivative-based Method for Function Approximation
Energy Technology Data Exchange (ETDEWEB)
Tong, C
2008-10-22
To alleviate the high computational cost of large-scale multi-physics simulations to study the relationships between the model parameters and the outputs of interest, response surfaces are often used in place of the exact functional relationships. This report explores a method for response surface construction using adaptive sampling guided by derivative information at each selected sample point. This method is especially suitable for applications that can readily provide added information such as gradients and Hessian with respect to the input parameters under study. When higher order terms (third and above) in the Taylor series are negligible, the approximation error for this method can be controlled. We present details of the adaptive algorithm and numerical results on a few test problems.
Approximate method for controlling solid elastic waves by transformation media
Hu, Jin; Chang, Zheng; Hu, Gengkai
2011-11-01
By idealizing a general mapping as a series of local affine ones, we derive approximately transformed material parameters necessary to control solid elastic waves within classical elasticity theory. The transformed elastic moduli are symmetric, and can be used with Navier's equation to manipulate elastic waves. It is shown numerically that the method can provide a powerful tool to control elastic waves in solids in case of high frequency or small material gradient. Potential applications can be anticipated in nondestructive testing, structure impact protection, petroleum exploration, and seismology.
Discrete Dipole Approximation Aided Design Method for Nanostructure Arrays
Institute of Scientific and Technical Information of China (English)
ZHU Shao-Li; LUO Xian-Gang; DU Chun-Lei
2007-01-01
A discrete dipole approximation (DDA) aided design method is proposed to determine the parameters of nanostructure arrays. The relationship between the thickness, period and extinction efficiency of nanostructure arrays for the given shape can be calculated using the DDA. Based on the calculated curves, the main parameters of the nanostructure arrays such as thickness and period can be determined. Using this aided method, a rhombic sliver nanostructure array is designed with the determinant parameters of thickness (40 nm) and period (440 nm).We further fabricate the rhombic sliver nanostructure arrays and testify the character of the extinction spectra.The obtained extinction spectra is within the visible range and the full width at half maximum is 99nm, as is expected.
Approximate design calculation methods for radiation streaming in shield irregularities
Energy Technology Data Exchange (ETDEWEB)
Miura, Toshimasa; Hirao, Yoshihiro [Ship Research Inst., Mitaka, Tokyo (Japan); Yoritsune, Tsutomu
1997-10-01
Investigation and assessment are made for approximate design calculation methods of radiation streaming in shield irregularities. Investigation is made for (1) source, (2) definition of streaming radiation components, (3) calculation methods of streaming radiation, (4) streaming formulas for each irregularity, (5) difficulties in application of streaming formulas, etc. Furthermore, investigation is made for simple calculation codes and albedo data. As a result, it is clarified that streaming calculation formulas are not enough to cover various irregularities and their accuracy or application limit is not sufficiently clear. Accurate treatment is not made in the formulas with respect to the radiation behavior for slant incidence, bend part, offset etc., that results in too much safety factors in the design calculation and distrust of the streaming calculation. To overcome the state and improve the accuracy of the design calculation for shield irregularities, it is emphasized to assess existing formulas and develop better formulas based on systematic experimental studies. (author)
The method of approximate inverse theory and applications
Schuster, Thomas
2007-01-01
Inverse problems arise whenever one tries to calculate a required quantity from given measurements of a second quantity that is associated to the first one. Besides medical imaging and non-destructive testing, inverse problems also play an increasing role in other disciplines such as industrial and financial mathematics. Hence, there is a need for stable and efficient solvers. The book is concerned with the method of approximate inverse which is a regularization technique for stably solving inverse problems in various settings such as L2-spaces, Hilbert spaces or spaces of distributions. The performance and functionality of the method is demonstrated on several examples from medical imaging and non-destructive testing such as computerized tomography, Doppler tomography, SONAR, X-ray diffractometry and thermoacoustic computerized tomography. The book addresses graduate students and researchers interested in the numerical analysis of inverse problems and regularization techniques or in efficient solvers for the...
Multiuser detection and channel estimation: Exact and approximate methods
DEFF Research Database (Denmark)
Fabricius, Thomas
2003-01-01
This dissertation deals with optimal and close to optimal multiuser detection in Code Division Multiple Access. We derive optimal detection strategies in the sense of minimum expected probability of bit error, sequence error, and mean square error. These are implemented efficiently by the use...... of the Junction Tree Algorithm, which is a generalisation of Pearl's Belief Propagation, the BCJR, sum product, min/max sum, and Viterbi's algorithm. Although efficient algoithms, they have an inherent exponential complexity in the number of users when applied to CDMA multiuser detection. For this reason we....... We also derive optimal detectors when nuisance parameters such as the channel and noise level are unknown, and show how well the proposed methods fit into this framework via the Generalised Expectation Maximisation algorithm. Our numerical evaluation show that naive mean field annealing and adaptive...
Approximation method to compute domain related integrals in structural studies
Oanta, E.; Panait, C.; Raicu, A.; Barhalescu, M.; Axinte, T.
2015-11-01
Various engineering calculi use integral calculus in theoretical models, i.e. analytical and numerical models. For usual problems, integrals have mathematical exact solutions. If the domain of integration is complicated, there may be used several methods to calculate the integral. The first idea is to divide the domain in smaller sub-domains for which there are direct calculus relations, i.e. in strength of materials the bending moment may be computed in some discrete points using the graphical integration of the shear force diagram, which usually has a simple shape. Another example is in mathematics, where the surface of a subgraph may be approximated by a set of rectangles or trapezoids used to calculate the definite integral. The goal of the work is to introduce our studies about the calculus of the integrals in the transverse section domains, computer aided solutions and a generalizing method. The aim of our research is to create general computer based methods to execute the calculi in structural studies. Thus, we define a Boolean algebra which operates with ‘simple’ shape domains. This algebraic standpoint uses addition and subtraction, conditioned by the sign of every ‘simple’ shape (-1 for the shapes to be subtracted). By ‘simple’ shape or ‘basic’ shape we define either shapes for which there are direct calculus relations, or domains for which their frontiers are approximated by known functions and the according calculus is carried out using an algorithm. The ‘basic’ shapes are linked to the calculus of the most significant stresses in the section, refined aspect which needs special attention. Starting from this idea, in the libraries of ‘basic’ shapes, there were included rectangles, ellipses and domains whose frontiers are approximated by spline functions. The domain triangularization methods suggested that another ‘basic’ shape to be considered is the triangle. The subsequent phase was to deduce the exact relations for the
How the great scientists reasoned the scientific method in action
Tibbetts, Gary G
2012-01-01
The scientific method is one of the most basic and essential concepts across the sciences, ensuring that investigations are carried out with precision and thoroughness. The scientific method is typically taught as a step-by-step approach, but real examples from history are not always given. This book teaches the basic modes of scientific thought, not by philosophical generalizations, but by illustrating in detail how great scientists from across the sciences solved problems using scientific reason. Examples include Christopher Columbus, Joseph Priestly, Antoine Lavoisier, Michael Faraday, W
Decoherence of Entangled States Calculated by a Systematic Approximate Method
Institute of Scientific and Technical Information of China (English)
LIU Tao; FAN Yun-Xia; HUANG Shu-Weng; WANG Ke-Lin; WANG Yi
2007-01-01
In this paper the coherent-state approximation (CA) method is used to deal with the problem of the decoherence of the entangled states of two two-state systems. As the base of the discussion, the dissipation of one two-state system has been investigated at first. The improved results calculated by CA are given in the paper. It is shown that the right approaching behavior and scaling law have been obtained when CA is applied to the problem of dissipation of two two-state systems coupled with environment. The whole evolution process and calculated results of the decoherence of the entangled states show also the scaling law, right approaching behavior, and rich phenomenon.
On rational approximation methods for inverse source problems
Rundell, William
2011-02-01
The basis of most imaging methods is to detect hidden obstacles or inclusions within a body when one can only make measurements on an exterior surface. Such is the ubiquity of these problems, the underlying model can lead to a partial differential equation of any of the major types, but here we focus on the case of steady-state electrostatic or thermal imaging and consider boundary value problems for Laplace\\'s equation. Our inclusions are interior forces with compact support and our data consists of a single measurement of (say) voltage/current or temperature/heat flux on the external boundary. We propose an algorithm that under certain assumptions allows for the determination of the support set of these forces by solving a simpler "equivalent point source" problem, and which uses a Newton scheme to improve the corresponding initial approximation. © 2011 American Institute of Mathematical Sciences.
Methods of Approximation Theory in Complex Analysis and Mathematical Physics
Saff, Edward
1993-01-01
The book incorporates research papers and surveys written by participants ofan International Scientific Programme on Approximation Theory jointly supervised by Institute for Constructive Mathematics of University of South Florida at Tampa, USA and the Euler International Mathematical Instituteat St. Petersburg, Russia. The aim of the Programme was to present new developments in Constructive Approximation Theory. The topics of the papers are: asymptotic behaviour of orthogonal polynomials, rational approximation of classical functions, quadrature formulas, theory of n-widths, nonlinear approximation in Hardy algebras,numerical results on best polynomial approximations, wavelet analysis. FROM THE CONTENTS: E.A. Rakhmanov: Strong asymptotics for orthogonal polynomials associated with exponential weights on R.- A.L. Levin, E.B. Saff: Exact Convergence Rates for Best Lp Rational Approximation to the Signum Function and for Optimal Quadrature in Hp.- H. Stahl: Uniform Rational Approximation of x .- M. Rahman, S.K. ...
Indian Academy of Sciences (India)
P K Bera
2012-01-01
The approximate analytical bound-state solutions of the Schrödinger equation for the Wei Hua oscillator are carried out in N-dimensional space by taking Pekeris approximation scheme to the orbital centrifugal term. Solutions of the corresponding hyper-radial equation are obtained using the conventional Nikiforov–Uvarov (NU) method.
Approximation by randomly weighting method in censored regression model
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Censored regression ("Tobit") models have been in common use, and their linear hypothesis testings have been widely studied. However, the critical values of these tests are usually related to quantities of an unknown error distribution and estimators of nuisance parameters. In this paper, we propose a randomly weighting test statistic and take its conditional distribution as an approximation to null distribution of the test statistic. It is shown that, under both the null and local alternative hypotheses, conditionally asymptotic distribution of the randomly weighting test statistic is the same as the null distribution of the test statistic. Therefore, the critical values of the test statistic can be obtained by randomly weighting method without estimating the nuisance parameters. At the same time, we also achieve the weak consistency and asymptotic normality of the randomly weighting least absolute deviation estimate in censored regression model. Simulation studies illustrate that the per-formance of our proposed resampling test method is better than that of central chi-square distribution under the null hypothesis.
Approximation by randomly weighting method in censored regression model
Institute of Scientific and Technical Information of China (English)
WANG ZhanFeng; WU YaoHua; ZHAO LinCheng
2009-01-01
Censored regression ("Tobit") models have been in common use,and their linear hypothesis testings have been widely studied.However,the critical values of these tests are usually related to quantities of an unknown error distribution and estimators of nuisance parameters.In this paper,we propose a randomly weighting test statistic and take its conditional distribution as an approximation to null distribution of the test statistic.It is shown that,under both the null and local alternative hypotheses,conditionally asymptotic distribution of the randomly weighting test statistic is the same as the null distribution of the test statistic.Therefore,the critical values of the test statistic can be obtained by randomly weighting method without estimating the nuisance parameters.At the same time,we also achieve the weak consistency and asymptotic normality of the randomly weighting least absolute deviation estimate in censored regression model.Simulation studies illustrate that the performance of our proposed resampling test method is better than that of central chi-square distribution under the null hypothesis.
Epistemological development and judgments and reasoning about teaching methods.
Spence, Sarah; Helwig, Charles C
2013-01-01
Children's, adolescents', and adults' (N = 96 7-8, 10-11, and 13-14-year-olds and university students) epistemological development and its relation to judgments and reasoning about teaching methods was examined. The domain (scientific or moral), nature of the topic (controversial or noncontroversial), and teaching method (direct instruction by lectures versus class discussions) were systematically varied. Epistemological development was assessed in the aesthetics, values, and physical truth domains. All participants took the domain, nature of the topic, and teaching method into consideration in ways that showed age-related variations. Epistemological development in the value domain alone was predictive of preferences for class discussions and a critical perspective on teacher-centered direct instruction, even when age was controlled in the analysis.
Yang, Z
1994-09-01
Two approximate methods are proposed for maximum likelihood phylogenetic estimation, which allow variable rates of substitution across nucleotide sites. Three data sets with quite different characteristics were analyzed to examine empirically the performance of these methods. The first, called the "discrete gamma model," uses several categories of rates to approximate the gamma distribution, with equal probability for each category. The mean of each category is used to represent all the rates falling in the category. The performance of this method is found to be quite good, and four such categories appear to be sufficient to produce both an optimum, or near-optimum fit by the model to the data, and also an acceptable approximation to the continuous distribution. The second method, called "fixed-rates model", classifies sites into several classes according to their rates predicted assuming the star tree. Sites in different classes are then assumed to be evolving at these fixed rates when other tree topologies are evaluated. Analyses of the data sets suggest that this method can produce reasonable results, but it seems to share some properties of a least-squares pairwise comparison; for example, interior branch lengths in nonbest trees are often found to be zero. The computational requirements of the two methods are comparable to that of Felsenstein's (1981, J Mol Evol 17:368-376) model, which assumes a single rate for all the sites. PMID:7932792
Kuwahara, Hiroyuki; Myers, Chris J
2008-09-01
Given the substantial computational requirements of stochastic simulation, approximation is essential for efficient analysis of any realistic biochemical system. This paper introduces a new approximation method to reduce the computational cost of stochastic simulations of an enzymatic reaction scheme which in biochemical systems often includes rapidly changing fast reactions with enzyme and enzyme-substrate complex molecules present in very small counts. Our new method removes the substrate dissociation reaction by approximating the passage time of the formation of each enzyme-substrate complex molecule which is destined to a production reaction. This approach skips the firings of unimportant yet expensive reaction events, resulting in a substantial acceleration in the stochastic simulations of enzymatic reactions. Additionally, since all the parameters used in our new approach can be derived by the Michaelis-Menten parameters which can actually be measured from experimental data, applications of this approximation can be practical even without having full knowledge of the underlying enzymatic reaction. Here, we apply this new method to various enzymatic reaction systems, resulting in a speedup of orders of magnitude in temporal behavior analysis without any significant loss in accuracy. Furthermore, we show that our new method can perform better than some of the best existing approximation methods for enzymatic reactions in terms of accuracy and efficiency. PMID:18662102
An approximation method for diffusion based leaching models
International Nuclear Information System (INIS)
In connection with the fixation of nuclear waste in a glassy matrix equations have been derived for leaching models based on a uniform concentration gradient approximation, and hence a uniform flux, therefore requiring the use of only Fick's first law. In this paper we improve on the uniform flux approximation, developing and justifying the approach. The resulting set of equations are solved to a satisfactory approximation for a matrix dissolving at a constant rate in a finite volume of leachant to give analytical expressions for the time dependence of the thickness of the leached layer, the diffusional and dissolutional contribution to the flux, and the leachant composition. Families of curves are presented which cover the full range of all the physical parameters for this system. The same procedure can be readily extended to more complex systems. (author)
Structured matrix based methods for approximate polynomial GCD
Boito, Paola
2011-01-01
Defining and computing a greatest common divisor of two polynomials with inexact coefficients is a classical problem in symbolic-numeric computation. The first part of this book reviews the main results that have been proposed so far in the literature. As usual with polynomial computations, the polynomial GCD problem can be expressed in matrix form: the second part of the book focuses on this point of view and analyses the structure of the relevant matrices, such as Toeplitz, Toepliz-block and displacement structures. New algorithms for the computation of approximate polynomial GCD are presented, along with extensive numerical tests. The use of matrix structure allows, in particular, to lower the asymptotic computational cost from cubic to quadratic order with respect to polynomial degree. .
Analytical Evaluation of Beam Deformation Problem Using Approximate Methods
DEFF Research Database (Denmark)
Barari, Amin; Kimiaeifar, A.; Domairry, G.
2010-01-01
The beam deformation equation has very wide applications in structural engineering. As a differential equation, it has its own problem concerning existence, uniqueness and methods of solutions. Often, original forms of governing differential equations used in engineering problems are simplified, ...... Iteration Method (VIM). The comparisons of the results reveal that these methods are very effective, convenient and quite accurate for systems of non-linear differential equation....
Berezkin, V. E.; Lotov, A. V.; Lotova, E. A.
2014-06-01
Methods for approximating the Edgeworth-Pareto hull (EPH) of the set of feasible criteria vectors in nonlinear multicriteria optimization problems are examined. The relative efficiency of two EPH approximation methods based on classical methods of searching for local extrema of convolutions of criteria is experimentally studied for a large-scale applied problem (with several hundred variables). A hybrid EPH approximation method combining classical and genetic approximation methods is considered.
Mobile Monitoring and Reasoning Methods to Prevent Cardiovascular Diseases
Directory of Open Access Journals (Sweden)
Diego López-de-Ipiña
2013-05-01
Full Text Available With the recent technological advances, it is possible to monitor vital signs using Bluetooth-enabled biometric mobile devices such as smartphones, tablets or electric wristbands. In this manuscript, we present a system to estimate the risk of cardiovascular diseases in Ambient Assisted Living environments. Cardiovascular disease risk is obtained from the monitoring of the blood pressure by means of mobile devices in combination with other clinical factors, and applying reasoning techniques based on the Systematic Coronary Risk Evaluation Project charts. We have developed an end-to-end software application for patients and physicians and a rule-based reasoning engine. We have also proposed a conceptual module to integrate recommendations to patients in their daily activities based on information proactively inferred through reasoning techniques and context-awareness. To evaluate the platform, we carried out usability experiments and performance benchmarks.
Directory of Open Access Journals (Sweden)
Pierluigi Monaco
2016-10-01
Full Text Available Precision cosmology has recently triggered new attention on the topic of approximate methods for the clustering of matter on large scales, whose foundations date back to the period from the late 1960s to early 1990s. Indeed, although the prospect of reaching sub-percent accuracy in the measurement of clustering poses a challenge even to full N-body simulations, an accurate estimation of the covariance matrix of clustering statistics, not to mention the sampling of parameter space, requires usage of a large number (hundreds in the most favourable cases of simulated (mock galaxy catalogs. Combination of few N-body simulations with a large number of realizations performed with approximate methods gives the most promising approach to solve these problems with a reasonable amount of resources. In this paper I review this topic, starting from the foundations of the methods, then going through the pioneering efforts of the 1990s, and finally presenting the latest extensions and a few codes that are now being used in present-generation surveys and thoroughly tested to assess their performance in the context of future surveys.
Monaco, Pierluigi
2016-01-01
Precision cosmology has recently triggered new attention on the topic of approximate methods for the clustering of matter on large scales, whose foundations date back to the period from late '60s to early '90s. Indeed, although the prospect of reaching sub-percent accuracy in the measurement of clustering poses a challenge even to full N-body simulations, an accurate estimation of the covariance matrix of clustering statistics requires usage of a large number (hundreds in the most favourable cases) of simulated (mock) galaxy catalogs. Combination of few N-body simulations with a large number of realizations performed with approximate methods, combined with the shrinkage technique or a similar tool, gives the most promising approach to solve this problem with a reasonable amount of resources. In this paper I review this topic, starting from the foundations of the methods, then going through the pioneering efforts of the '90s, and finally presenting the latest extensions and a few codes that are now being used ...
Sherlock Holmes' methods of deductive reasoning applied to medical diagnostics.
Miller, L
1985-03-01
Having patterned the character of Sherlock Holmes after one of his professors, Sir Arthur Conan Doyle, himself a physician, incorporated many of the didactic qualities of the 19th century medical diagnostician into the character of Holmes. In this paper I explore Holmes's techniques of deductive reasoning and their basis in 19th and 20th century medical diagnostics.
Sherlock Holmes's Methods of Deductive Reasoning Applied to Medical Diagnostics
Miller, Larry
1985-01-01
Having patterned the character of Sherlock Holmes after one of his professors, Sir Arthur Conan Doyle, himself a physician, incorporated many of the didactic qualities of the 19th century medical diagnostician into the character of Holmes. In this paper I explore Holmes's techniques of deductive reasoning and their basis in 19th and 20th century medical diagnostics.
Sherlock Holmes's Methods of Deductive Reasoning Applied to Medical Diagnostics
Miller, Larry
1985-01-01
Having patterned the character of Sherlock Holmes after one of his professors, Sir Arthur Conan Doyle, himself a physician, incorporated many of the didactic qualities of the 19th century medical diagnostician into the character of Holmes. In this paper I explore Holmes's techniques of deductive reasoning and their basis in 19th and 20th century medical diagnostics. PMID:3887762
Sherlock Holmes' methods of deductive reasoning applied to medical diagnostics.
Miller, L
1985-03-01
Having patterned the character of Sherlock Holmes after one of his professors, Sir Arthur Conan Doyle, himself a physician, incorporated many of the didactic qualities of the 19th century medical diagnostician into the character of Holmes. In this paper I explore Holmes's techniques of deductive reasoning and their basis in 19th and 20th century medical diagnostics. PMID:3887762
α-Automated Reasoning Method Based on Lattice-Valued Propositional Logic LP(X)
Institute of Scientific and Technical Information of China (English)
王伟; 徐扬; 王学芳
2002-01-01
This paper is focused on automated reasoning based on classical propositional logic and lattice-valued propositional logic LP(X). A new method of automated reasoning is given, and the soundness and completeness theorems of this method are proved.
Elastic wave scattering calculations and the matrix variational Pade approximant method
International Nuclear Information System (INIS)
The matrix variational Pade approximant and its generalization to elastic wave scattering are discussed. Predictions of the method for the scattering of a longitudinal plane wave are compared with the exact scattering from spherical voids and inclusions. Its predictions are also compared to those of the first and second Born approximations and to the standard matrix Pade approximant based on these Born approximations
26 CFR 1.412(c)(3)-1 - Reasonable funding methods.
2010-04-01
... 26 Internal Revenue 5 2010-04-01 2010-04-01 false Reasonable funding methods. 1.412(c)(3)-1... Reasonable funding methods. (a) Introduction—(1) In general. This section prescribes rules for determining whether or not, in the case of an ongoing plan, a funding method is reasonable for purposes of section...
SET: a pupil detection method using sinusoidal approximation.
Javadi, Amir-Homayoun; Hakimi, Zahra; Barati, Morteza; Walsh, Vincent; Tcheang, Lili
2015-01-01
Mobile eye-tracking in external environments remains challenging, despite recent advances in eye-tracking software and hardware engineering. Many current methods fail to deal with the vast range of outdoor lighting conditions and the speed at which these can change. This confines experiments to artificial environments where conditions must be tightly controlled. Additionally, the emergence of low-cost eye tracking devices calls for the development of analysis tools that enable non-technical researchers to process the output of their images. We have developed a fast and accurate method (known as "SET") that is suitable even for natural environments with uncontrolled, dynamic and even extreme lighting conditions. We compared the performance of SET with that of two open-source alternatives by processing two collections of eye images: images of natural outdoor scenes with extreme lighting variations ("Natural"); and images of less challenging indoor scenes ("CASIA-Iris-Thousand"). We show that SET excelled in outdoor conditions and was faster, without significant loss of accuracy, indoors. SET offers a low cost eye-tracking solution, delivering high performance even in challenging outdoor environments. It is offered through an open-source MATLAB toolkit as well as a dynamic-link library ("DLL"), which can be imported into many programming languages including C# and Visual Basic in Windows OS (www.eyegoeyetracker.co.uk). PMID:25914641
SET: A Pupil Detection Method Using Sinusoidal Approximation
Directory of Open Access Journals (Sweden)
Amir-Homayoun eJavadi
2015-04-01
Full Text Available Mobile eye-tracking in external environments remains challenging, despite recent advances in eye-tracking software and hardware engineering. Many current methods fail to deal with the vast range of outdoor lighting conditions and the speed at which these can change. This confines experiments to artificial environments where conditions must be tightly controlled. Additionally, the emergence of low-cost eye tracking devices calls for the development of analysis tools that enable non-technical researchers to process the output of their images. We have developed a fast and accurate method (known as ‘SET’ that is suitable even for natural environments with uncontrolled, dynamic and even extreme lighting conditions. We compared the performance of SET with that of two open-source alternatives by processing two collections of eye images: images of natural outdoor scenes with extreme lighting variations (‘Natural’; and images of less challenging indoor scenes (‘CASIA-Iris-Thousand’. We show that SET excelled in outdoor conditions and was faster, without significant loss of accuracy, indoors. SET offers a low cost eye-tracking solution, delivering high performance even in challenging outdoor environments. It is offered through an open-source MATLAB toolkit as well as a dynamic-link library (‘DLL’, which can be imported into many programming languages including C# and Visual Basic in Windows OS (www.eyegoeyetracker.co.uk.
A new method to obtain approximate symmetry of nonlinear evolution equation from perturbations
Institute of Scientific and Technical Information of China (English)
Zhang Zhi-Yong; Yong Xue-Lin; Chen Yu-Fu
2009-01-01
A novel method for obtaining the approximate symmetry of a partial differential equation with a small parameter is introduced. By expanding the independent variable and the dependent variable in the small parameter series, we obtain more affluent approximate symmetries. The method is applied to two perturbed nonlinear partial differential equations and new approximate solutions are derived.
Fuzzy Reasoning Methods by Choosing Different Fuzzy Counters and Analysis of Effect
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Different fuzzy reasoning methods were gave by choosing different fuzzy counters. This article generally introduced the basic structure of fuzzy controller,and compared and analysised the reasoning effect of fuzzy reasoning methods and the effect of computer simulating control basicly on different fuzzy counters.
Convergence of hausdorff approximation methods for the Edgeworth-Pareto hull of a compact set
Efremov, R. V.
2015-11-01
The Hausdorff methods comprise an important class of polyhedral approximation methods for convex compact bodies, since they have an optimal convergence rate and possess other useful properties. The concept of Hausdorff methods is extended to a problem arising in multicriteria optimization, namely, to the polyhedral approximation of the Edgeworth-Pareto hull (EPH) of a convex compact set. It is shown that the sequences of polyhedral sets generated by Hausdorff methods converge to the EPH to be approximated. It is shown that the Estimate Refinement method, which is most frequently used to approximate the EPH of convex compact sets, is a Hausdorff method and, hence, generates sequences of sets converging to the EPH.
Automated Reasoning and Equation Solving with the Characteristic Set Method
Institute of Scientific and Technical Information of China (English)
Wen-Tsun Wu; Xiao-Shan Gao
2006-01-01
A brief introduction to the characteristic set method is given for solving algebraic equation systems and then the method is extended to algebraic difference systems. The method can be used to decompose the zero set for a difference polynomial set in general form to the union of difference polynomial sets in triangular form. Based on the characteristic set method, a decision procedure for the first order theory over an algebraically closed field and a procedure to prove certain difference identities are proposed.
Reverse triple I method of restriction for fuzzy reasoning
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
A theory of reverse triple I method of restriction for implication operator R0 is proposed.And the general computation formulas of infimum for fuzzy modus ponens and supremum for fuzzy modus tollens of a-reverse triple I method of restriction are obtained respectively.
THE CONVERGENCE OF APPROACH PENALTY FUNCTION METHOD FOR APPROXIMATE BILEVEL PROGRAMMING PROBLEM
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
In this paper, a new algorithm-approximate penalty function method is designed, which can be used to solve a bilevel optimization problem with linear constrained function. In this kind of bilevel optimization problem, the evaluation of the objective function is very difficult, so that only their approximate values can be obtained. This algorithm is obtained by combining penalty function method and approximation in bilevel programming. The presented algorithm is completely different from existing methods. That convergence for this algorithm is proved.
Pospelov, A. I.
2016-08-01
Adaptive methods for the polyhedral approximation of the convex Edgeworth-Pareto hull in multiobjective monotone integer optimization problems are proposed and studied. For these methods, theoretical convergence rate estimates with respect to the number of vertices are obtained. The estimates coincide in order with those for filling and augmentation H-methods intended for the approximation of nonsmooth convex compact bodies.
The Financial Impact of Risk Factors Affecting Project Cost Contingency: Evidential Reasoning Method
Directory of Open Access Journals (Sweden)
Emmanuel Abeere-Inga
2013-07-01
Full Text Available The process of cost modeling using risk analysis for construction projects is very crucial for the achievement of project success. The purpose of this paper is to present an analysis of the financial impact of risk factors affecting key construction work sections; using a systematic risk methodology based on empirical judgment. The failure mode effect analysis (FMEA and the evidential reasoning methods are presented as qualitative and quantitative risk tools respectively. Data analysis from structured questionnaires revealed that four work sections are prone to high scope changes contemporaneous with seven risk factors. Contrary to the usual 10% contingency estimate allowed for construction projects in Ghana, an approximate overall physical contingency range of between 13.36% and 17.88% was determined using evidential reasoning methods. The likely impact of the integrated work sections and risk factors provide a clue to estimators on how to estimate and account for project cost contingency. The research concludes by recommending a framework for improving the estimation process of cost contingency through the integration of efficient risk management strategies, cost estimation and design management process.
Beam propagation method using a [(p- 1)/ p] Padé approximant of the propagator.
Lu, Ya Yan; Ho, Pui Lin
2002-05-01
A new beam propagation method (BPM) is developed based on a direct approximation to the propagator by its [(p-1)/p] Padé approximant. The approximant is simple to construct and has the desired damping effect for the evanescent modes. The method is applied to a tapered waveguide for TM-polarized waves, based on the energy-conserving improvement of the one-way Helmholtz equation. Numerical results are compared with those obtained with other variants of the BPM. PMID:18007898
Efficient Path Query and Reasoning Method Based on Rare Axis
Institute of Scientific and Technical Information of China (English)
姜洋; 冯志勇; 王鑫马晓宁
2015-01-01
A new concept of rare axis based on statistical facts is proposed, and an evaluation algorithm is designed thereafter. For the nested regular expressions containing rare axes, the proposed algorithm can reduce its evaluation complexity from polynomial time to nearly linear time. The distributed technique is also employed to construct the navigation axis indexes for resource description framework (RDF) graph data. Experiment results in DrugBank and BioGRID show that this method can improve the query efficiency significantly while ensuring the accuracy and meet the query requirements on Web-scale RDF graph data.
A NEW TWO-POINT ADAPTIVENONLINEAR APPROXIMATION METHOD FOR RELIABILITY ANALYSIS
Institute of Scientific and Technical Information of China (English)
LiuShutian
2004-01-01
A two-point adaptive nonlinear approximation (referred to as TANA4) suitable for reliability analysis is proposed. Transformed and normalized random variables in probabilistic analysis could become negative and pose a challenge to the earlier developed two-point approximations; thus a suitable method that can address this issue is needed. In the method proposed, the nonlinearity indices of intervening variables are limited to integers. Then, on the basis of the present method, an improved sequential approximation of the limit state surface for reliability analysis is presented. With the gradient projection method, the data points for the limit state surface approximation are selected on the original limit state surface, which effectively represents the nature of the original response function. On the basis of this new approximation, the reliability is estimated using a first-order second-moment method. Various examples, including both structural and non-structural ones, are presented to show the effectiveness of the method proposed.
Reason and Condition for Mode Kissing in MASW Method
Gao, Lingli; Xia, Jianghai; Pan, Yudi; Xu, Yixian
2016-05-01
Identifying correct modes of surface waves and picking accurate phase velocities are critical for obtaining an accurate S-wave velocity in MASW method. In most cases, inversion is easily conducted by picking the dispersion curves corresponding to different surface-wave modes individually. Neighboring surface-wave modes, however, will nearly meet (kiss) at some frequencies for some models. Around the frequencies, they have very close roots and energy peak shifts from one mode to another. At current dispersion image resolution, it is difficult to distinguish different modes when mode-kissing occurs, which is commonly seen in near-surface earth models. It will cause mode misidentification, and as a result, lead to a larger overestimation of S-wave velocity and error on depth. We newly defined two mode types based on the characteristics of the vertical eigendisplacements calculated by generalized reflection and transmission coefficient method. Rayleigh-wave mode near the kissing points (osculation points) change its type, that is to say, one Rayleigh-wave mode will contain different mode types. This mode type conversion will cause the mode-kissing phenomenon in dispersion images. Numerical tests indicate that the mode-kissing phenomenon is model dependent and that the existence of strong S-wave velocity contrasts increases the possibility of mode-kissing. The real-world data shows mode misidentification caused by mode-kissing phenomenon will result in higher S-wave velocity of bedrock. It reminds us to pay attention to this phenomenon when some of the underground information is known.
A Method to Improve First Order Approximation of Smoothed Particle Hydrodynamics
Institute of Scientific and Technical Information of China (English)
CHEN Si; ZHOU Dai; BAO Yan; DONG Shi-lin
2008-01-01
Smoothed particle hydrodynamics (SPH) is a useful meshless method. The first and second ordersare the most popular derivatives of the field function in the mechanical governing equations. New methodswere proposed to improve accuracy of SPH approximation by the lemma proved. The lemma describes therelationship of functions and their SPH approximation. Finally, the error comparison of SPH method with orwithout our improvement was carried out.
Energy Technology Data Exchange (ETDEWEB)
Yoo, J.; Shin, H. S.; Song, T. Y.; Park, W. S. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)
1997-12-31
Previous our numerical results in computing point kinetics equations show a possibility in developing approximations to estimate sensitivity responses of nuclear reactor. We recalculate sensitivity responses by maintaining the corrections with first order of sensitivity parameter. We present a method for computing sensitivity responses of nuclear reactor based on an approximation derived from point kinetics equations. Exploiting this approximation, we found that the first order approximation works to estimate variations in the time to reach peak power because of their linear dependence on a sensitivity parameter, and that there are errors in estimating the peak power in the first order approximation for larger sensitivity parameters. To confirm legitimacy of out approximation, these approximate results are compared with exact results obtained from out previous numerical study. 4 refs., 2 figs., 3 tabs. (Author)
Lawrenz, Frances
1985-01-01
Determined: (1) if elementary education majors (N=91) from different levels of reasoning ability learned more science concepts under different grouping methods in an inquiry/learning cycle-based physical science class; and (2) if these students became able to reason more effectively under the different grouping methods. (JN)
An explicit approximate solution to the Duffing-harmonic oscillator by a cubication method
Energy Technology Data Exchange (ETDEWEB)
Belendez, A., E-mail: a.belendez@ua.e [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Mendez, D.I. [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, E. [Departamento de Optica, Farmacologia y Anatomia, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Marini, S. [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Pascual, I. [Departamento de Optica, Farmacologia y Anatomia, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)
2009-08-03
The nonlinear oscillations of a Duffing-harmonic oscillator are investigated by an approximated method based on the 'cubication' of the initial nonlinear differential equation. In this cubication method the restoring force is expanded in Chebyshev polynomials and the original nonlinear differential equation is approximated by a Duffing equation in which the coefficients for the linear and cubic terms depend on the initial amplitude, A. The replacement of the original nonlinear equation by an approximate Duffing equation allows us to obtain explicit approximate formulas for the frequency and the solution as a function of the complete elliptic integral of the first kind and the Jacobi elliptic function, respectively. These explicit formulas are valid for all values of the initial amplitude and we conclude this cubication method works very well for the whole range of initial amplitudes. Excellent agreement of the approximate frequencies and periodic solutions with the exact ones is demonstrated and discussed and the relative error for the approximate frequency is as low as 0.071%. Unlike other approximate methods applied to this oscillator, which are not capable to reproduce exactly the behaviour of the approximate frequency when A tends to zero, the cubication method used in this Letter predicts exactly the behaviour of the approximate frequency not only when A tends to infinity, but also when A tends to zero. Finally, a closed-form expression for the approximate frequency is obtained in terms of elementary functions. To do this, the relationship between the complete elliptic integral of the first kind and the arithmetic-geometric mean as well as Legendre's formula to approximately obtain this mean are used.
A NEW SMOOTHING APPROXIMATION METHOD FOR SOLVING BOX CONSTRAINED VARIATIONAL INEQUALITIES
Institute of Scientific and Technical Information of China (English)
Chang-feng Ma; Guo-ping Liang; Shao-peng Liu
2002-01-01
In this paper, we first give a smoothing approximation function of nonsmooth system based on box constrained variational inequalities and then present a new smoothing approximation algorithm. Under suitable conditions,we show that the method is globally and superlinearly convergent. A few numerical results are also reported in the paper.
An Approximate Proximal Bundle Method to Minimize a Class of Maximum Eigenvalue Functions
Directory of Open Access Journals (Sweden)
Wei Wang
2014-01-01
Full Text Available We present an approximate nonsmooth algorithm to solve a minimization problem, in which the objective function is the sum of a maximum eigenvalue function of matrices and a convex function. The essential idea to solve the optimization problem in this paper is similar to the thought of proximal bundle method, but the difference is that we choose approximate subgradient and function value to construct approximate cutting-plane model to solve the above mentioned problem. An important advantage of the approximate cutting-plane model for objective function is that it is more stable than cutting-plane model. In addition, the approximate proximal bundle method algorithm can be given. Furthermore, the sequences generated by the algorithm converge to the optimal solution of the original problem.
Efficiency of the estimate refinement method for polyhedral approximation of multidimensional balls
Kamenev, G. K.
2016-05-01
The estimate refinement method for the polyhedral approximation of convex compact bodies is analyzed. When applied to convex bodies with a smooth boundary, this method is known to generate polytopes with an optimal order of growth of the number of vertices and facets depending on the approximation error. In previous studies, for the approximation of a multidimensional ball, the convergence rates of the method were estimated in terms of the number of faces of all dimensions and the cardinality of the facial structure (the norm of the f-vector) of the constructed polytope was shown to have an optimal rate of growth. In this paper, the asymptotic convergence rate of the method with respect to faces of all dimensions is compared with the convergence rate of best approximation polytopes. Explicit expressions are obtained for the asymptotic efficiency, including the case of low dimensions. Theoretical estimates are compared with numerical results.
Directory of Open Access Journals (Sweden)
Xiao-Ying Qin
2014-01-01
Full Text Available An Adomian decomposition method (ADM is applied to solve a two-phase Stefan problem that describes the pure metal solidification process. In contrast to traditional analytical methods, ADM avoids complex mathematical derivations and does not require coordinate transformation for elimination of the unknown moving boundary. Based on polynomial approximations for some known and unknown boundary functions, approximate analytic solutions for the model with undetermined coefficients are obtained using ADM. Substitution of these expressions into other equations and boundary conditions of the model generates some function identities with the undetermined coefficients. By determining these coefficients, approximate analytic solutions for the model are obtained. A concrete example of the solution shows that this method can easily be implemented in MATLAB and has a fast convergence rate. This is an efficient method for finding approximate analytic solutions for the Stefan and the inverse Stefan problems.
Approximation analytical solutions for a unified plasma sheath model by double decomposition method
Institute of Scientific and Technical Information of China (English)
FangJin－Qing
1998-01-01
A unified plasma sheath model and its potential equation are proposed.Any higher-order approximation analytical solutions for the unified plasma sheath potential equation are derived by double decomposition method.
Evaluation of the successive approximations method for acoustic streaming numerical simulations.
Catarino, S O; Minas, G; Miranda, J M
2016-05-01
This work evaluates the successive approximations method commonly used to predict acoustic streaming by comparing it with a direct method. The successive approximations method solves both the acoustic wave propagation and acoustic streaming by solving the first and second order Navier-Stokes equations, ignoring the first order convective effects. This method was applied to acoustic streaming in a 2D domain and the results were compared with results from the direct simulation of the Navier-Stokes equations. The velocity results showed qualitative agreement between both methods, which indicates that the successive approximations method can describe the formation of flows with recirculation. However, a large quantitative deviation was observed between the two methods. Further analysis showed that the successive approximation method solution is sensitive to the initial flow field. The direct method showed that the instantaneous flow field changes significantly due to reflections and wave interference. It was also found that convective effects contribute significantly to the wave propagation pattern. These effects must be taken into account when solving the acoustic streaming problems, since it affects the global flow. By adequately calculating the initial condition for first order step, the acoustic streaming prediction by the successive approximations method can be improved significantly.
Evaluation of the successive approximations method for acoustic streaming numerical simulations.
Catarino, S O; Minas, G; Miranda, J M
2016-05-01
This work evaluates the successive approximations method commonly used to predict acoustic streaming by comparing it with a direct method. The successive approximations method solves both the acoustic wave propagation and acoustic streaming by solving the first and second order Navier-Stokes equations, ignoring the first order convective effects. This method was applied to acoustic streaming in a 2D domain and the results were compared with results from the direct simulation of the Navier-Stokes equations. The velocity results showed qualitative agreement between both methods, which indicates that the successive approximations method can describe the formation of flows with recirculation. However, a large quantitative deviation was observed between the two methods. Further analysis showed that the successive approximation method solution is sensitive to the initial flow field. The direct method showed that the instantaneous flow field changes significantly due to reflections and wave interference. It was also found that convective effects contribute significantly to the wave propagation pattern. These effects must be taken into account when solving the acoustic streaming problems, since it affects the global flow. By adequately calculating the initial condition for first order step, the acoustic streaming prediction by the successive approximations method can be improved significantly. PMID:27250122
An Iterative Method for the Approximation of Fibers in Slow-Fast Systems
DEFF Research Database (Denmark)
Kristiansen, Kristian Uldall; Brøns, Morten; Starke, Jens
2014-01-01
In this paper we extend a method for iteratively improving slow manifolds so that it also can be used to approximate the fiber directions. The extended method is applied to general finite-dimensional real analytic systems where we obtain exponential estimates of the tangent spaces to the fibers....... The method is demonstrated on the Michaelis--Menten--Henri model and the Lindemann mechanism. The latter example also serves to demonstrate the method on a slow-fast system in nonstandard slow-fast form. Finally, we extend the method further so that it also approximates the curvature of the fibers....
OPTIMAL ERROR ESTIMATES OF THE PARTITION OF UNITY METHOD WITH LOCAL POLYNOMIAL APPROXIMATION SPACES
Institute of Scientific and Technical Information of China (English)
Yun-qing Huang; Wei Li; Fang Su
2006-01-01
In this paper, we provide a theoretical analysis of the partition of unity finite element method(PUFEM), which belongs to the family of meshfree methods. The usual error analysis only shows the order of error estimate to the same as the local approximations[12].Using standard linear finite element base functions as partition of unity and polynomials as local approximation space, in 1-d case, we derive optimal order error estimates for PUFEM interpolants. Our analysis show that the error estimate is of one order higher than the local approximations. The interpolation error estimates yield optimal error estimates for PUFEM solutions of elliptic boundary value problems.
A New Inexactness Criterion for Approximate Logarithmic-Quadratic Proximal Methods
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Recently, a class of logarithmic-quadratic proximal (LQP) methods was introduced by Auslender, Teboulle and Ben-Tiba. The inexact versions of these methods solve the sub-problems in each iteration approximately. In this paper, we present a practical inexactness criterion for the inexact version of these methods.
ON THE CONVERGENCE OF AN APPROXIMATE PROXIMAL METHOD FOR DC FUNCTIONS
Institute of Scientific and Technical Information of China (English)
A. Moudafi; P-E. Maingé
2006-01-01
In this paper we prove the convergence of the approximate proximal method for DC functions proposed by Sun et al [6]. Our analysis also permits to treat the exact method.We then propose an interesting result in the case where the second component of the DC function is differentiable and provide some computational experiences which proved the efficiency of our method.
Bota, C.; Cǎruntu, B.; Bundǎu, O.
2013-10-01
In this paper we applied the Squared Remainder Minimization Method (SRMM) to find analytic approximate polynomial solutions for Riccati differential equations. Two examples are included to demonstrated the validity and applicability of the method. The results are compared to those obtained by other methods.
A new approximation method for time-dependent problems in quantum mechanics
Energy Technology Data Exchange (ETDEWEB)
Amore, Paolo [Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima, Colima (Mexico)]. E-mail: paolo@ucol.mx; Aranda, Alfredo [Facultad de Ciencias, Universidad de Colima, Bernal Diaz del Castillo 340, Colima, Colima (Mexico)]. E-mail: fefo@ucol.mx; Fernandez, Francisco M. [INIFTA (Conicet, UNLP), Diag. 113 y 64 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)]. E-mail: fernande@quimica.unlp.edu.ar; Jones, Hugh [Department of Physics, Imperial College, London SW7 2AZ (United Kingdom)]. E-mail: h.f.jones@imperial.ac.uk
2005-06-06
We propose an approximate solution of the time-dependent Schroedinger equation using the method of stationary states combined with a variational matrix method for finding the energies and eigenstates. We illustrate the effectiveness of the method by applying it to the time development of the wave-function in the quantum-mechanical version of the inflationary slow-roll transition.
Institute of Scientific and Technical Information of China (English)
无
1990-01-01
Fuzzy set systems can be used to solve the problem with uncertain knowledge,and default logic can be used to solve the problem with incomplete knowledge,in some sense.In this paper,based on interval-valued fuzzy sets we introduce a method of inference which combines approximate reasoning an default ogic,and give the procedure of transforming monotonic reasoning into default reasoning.
Institute of Scientific and Technical Information of China (English)
Fran(c)ois Chaplais
2006-01-01
In applications it is useful to compute the local average of a function f(u) of an input u from empirical statistics on u. A very simple relation exists when the local averages are given by a Haar approximation. The question is to know if it holds for higher order approximation methods. To do so,it is necessary to use approximate product operators defined over linear approximation spaces. These products are characterized by a Strang and Fix like condition. An explicit construction of these product operators is exhibited for piecewise polynomial functions, using Hermite interpolation. The averaging relation which holds for the Haar approximation is then recovered when the product is defined by a two point Hermite interpolation.
A method to reduce ambiguities of qualitative reasoning for conceptual design applications
D'Amelio, V.; Chmarra, M.K.; Tomiyama, T.
2013-01-01
Qualitative reasoning can generate ambiguous behaviors due to the lack of quantitative information. Despite many different research results focusing on ambiguities reduction, fundamentally it is impossible to totally remove ambiguities with only qualitative methods and to guarantee the consistency o
Analytical approximate solution of the cooling problem by Adomian decomposition method
Alizadeh, Ebrahim; Sedighi, Kurosh; Farhadi, Mousa; Ebrahimi-Kebria, H. R.
2009-02-01
The Adomian decomposition method (ADM) can provide analytical approximation or approximated solution to a rather wide class of nonlinear (and stochastic) equations without linearization, perturbation, closure approximation, or discretization methods. In the present work, ADM is employed to solve the momentum and energy equations for laminar boundary layer flow over flat plate at zero incidences with neglecting the frictional heating. A trial and error strategy has been used to obtain the constant coefficient in the approximated solution. ADM provides an analytical solution in the form of an infinite power series. The effect of Adomian polynomial terms is considered and shows that the accuracy of results is increased with the increasing of Adomian polynomial terms. The velocity and thermal profiles on the boundary layer are calculated. Also the effect of the Prandtl number on the thermal boundary layer is obtained. Results show ADM can solve the nonlinear differential equations with negligible error compared to the exact solution.
Directory of Open Access Journals (Sweden)
Birol İbiş
2014-01-01
Full Text Available This paper aims to obtain the approximate solution of time-fractional advection-dispersion equation (FADE involving Jumarie’s modification of Riemann-Liouville derivative by the fractional variational iteration method (FVIM. FVIM provides an analytical approximate solution in the form of a convergent series. Some examples are given and the results indicate that the FVIM is of high accuracy, more efficient, and more convenient for solving time FADEs.
Energy Technology Data Exchange (ETDEWEB)
Sin, M. W.; Kim, M. H. [Kyunghee Univ., Yongin (Korea, Republic of)
2002-10-01
To calculate total dose effect on semi-conductor devices in satellite for a period of space mission effectively, two approximate calculation models for a comic radiation shielding were proposed. They are a sectoring method and a chord-length distribution method. When an approximate method was applied in this study, complex structure of satellite was described into multiple 1-dimensional slabs, structural materials were converted to reference material(aluminum), and the pre-calculated dose-depth conversion function was introduced to simplify the calculation process. Verification calculation was performed for orbit location and structure geometry of KITSAT-1 and compared with detailed 3-dimensional calculation results and experimental values. The calculation results from approximate method were estimated conservatively with acceptable error. However, results for satellite mission simulation were underestimated in total dose rate compared with experimental values.
Directory of Open Access Journals (Sweden)
S. Das
2013-12-01
Full Text Available In this article, optimal homotopy-analysis method is used to obtain approximate analytic solution of the time-fractional diffusion equation with a given initial condition. The fractional derivatives are considered in the Caputo sense. Unlike usual Homotopy analysis method, this method contains at the most three convergence control parameters which describe the faster convergence of the solution. Effects of parameters on the convergence of the approximate series solution by minimizing the averaged residual error with the proper choices of parameters are calculated numerically and presented through graphs and tables for different particular cases.
Directory of Open Access Journals (Sweden)
Shafaghi Afshin
2011-10-01
Full Text Available Abstract Background Clinical reasoning plays a major role in the ability of doctors to make a diagnosis and reach treatment decisions. This paper describes the use of four clinical reasoning tests in the second National Medical Science Olympiad in Iran: key features (KF, script concordance (SCT, clinical reasoning problems (CRP and comprehensive integrative puzzles (CIP. The purpose of the study was to design a multi instrument for multiple roles approach in clinical reasoning field based on the theoretical framework, KF was used to measure data gathering, CRP was used to measure hypothesis formation, SCT and CIP were used to measure hypothesis evaluation and investigating the combined use of these tests in the Olympiad. A bank of clinical reasoning test items was developed for emergency medicine by a scientific expert committee representing all the medical schools in the country. These items were pretested by a reference group and the results were analyzed to select items that could be omitted. Then 135 top-ranked medical students from 45 medical universities in Iran participated in the clinical domain of the Olympiad. The reliability of each test was calculated by Cronbach's alpha. Item difficulty and the correlation between each item and the total score were measured. The correlation between the students' final grade and each of the clinical reasoning tests was calculated, as was the correlation between final grades and another measure of knowledge, i.e., the students' grade point average. Results The combined reliability for all four clinical reasoning tests was 0.91. Of the four clinical reasoning tests we compared, reliability was highest for CIP (0.91. The reliability was 0.83 for KF, 0.78 for SCT and 0.71 for CRP. Most of the tests had an acceptable item difficulty level between 0.2 and 0.8. The correlation between the score for each item and the total test score for each of the four tests was positive. The correlations between scores
Approximate Analytic and Numerical Solutions to Lane-Emden Equation via Fuzzy Modeling Method
Directory of Open Access Journals (Sweden)
De-Gang Wang
2012-01-01
Full Text Available A novel algorithm, called variable weight fuzzy marginal linearization (VWFML method, is proposed. This method can supply approximate analytic and numerical solutions to Lane-Emden equations. And it is easy to be implemented and extended for solving other nonlinear differential equations. Numerical examples are included to demonstrate the validity and applicability of the developed technique.
Analytical Approximation Methods for the Stabilizing Solution of the Hamilton–Jacobi Equation
Sakamoto, Noboru; Schaft, Arjan J. van der
2008-01-01
In this paper, two methods for approximating the stabilizing solution of the Hamilton–Jacobi equation are proposed using symplectic geometry and a Hamiltonian perturbation technique as well as stable manifold theory. The first method uses the fact that the Hamiltonian lifted system of an integrable
Analytical Approximation Methods for the Stabilizing Solution of the Hamilton-Jacobi Equation
Sakamoto, Noboru; van der Schaft, Arjan J.
2008-01-01
In this paper, two methods for approximating the stabilizing solution of the Hamilton-Jacobi equation are proposed using symplectic geometry and a Hamiltonian perturbation technique as well as stable manifold theory. The first method uses the fact that the Hamiltonian lifted system of an integrable
Numerical solution of 2D-vector tomography problem using the method of approximate inverse
Svetov, Ivan; Maltseva, Svetlana; Polyakova, Anna
2016-08-01
We propose a numerical solution of reconstruction problem of a two-dimensional vector field in a unit disk from the known values of the longitudinal and transverse ray transforms. The algorithm is based on the method of approximate inverse. Numerical simulations confirm that the proposed method yields good results of reconstruction of vector fields.
Quantum Approximate Methods for the Atomistic Modeling of Multicomponent Alloys. Chapter 7
Bozzolo, Guillermo; Garces, Jorge; Mosca, Hugo; Gargano, pablo; Noebe, Ronald D.; Abel, Phillip
2007-01-01
This chapter describes the role of quantum approximate methods in the understanding of complex multicomponent alloys at the atomic level. The need to accelerate materials design programs based on economical and efficient modeling techniques provides the framework for the introduction of approximations and simplifications in otherwise rigorous theoretical schemes. As a promising example of the role that such approximate methods might have in the development of complex systems, the BFS method for alloys is presented and applied to Ru-rich Ni-base superalloys and also to the NiAI(Ti,Cu) system, highlighting the benefits that can be obtained from introducing simple modeling techniques to the investigation of such complex systems.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
An approximate homotopy symmetry method for nonlinear problems is proposed and applied to the sixth-order Boussinesq equation,which arises from fluid dynamics.We summarize the general formulas for similarity reduction solutions and similarity reduction equations of different orders,educing the related homotopy series solutions.Zero-order similarity reduction equations are equivalent to the Painlevé IV type equation or Weierstrass elliptic equation.Higher order similarity solutions can be obtained by solving linear variable coefficients ordinary differential equations.The auxiliary parameter has an effect on the convergence of homotopy series solutions.Series solutions and similarity reduction equations from the approximate symmetry method can be retrieved from the approximate homotopy symmetry method.
Christian, Karen Jeanne
2011-12-01
Students often use study groups to prepare for class or exams; yet to date, we know very little about how these groups actually function. This study looked at the ways in which undergraduate organic chemistry students prepared for exams through self-initiated study groups. We sought to characterize the methods of social regulation, levels of content processing, and types of reasoning processes used by students within their groups. Our analysis showed that groups engaged in predominantly three types of interactions when discussing chemistry content: co-construction, teaching, and tutoring. Although each group engaged in each of these types of interactions at some point, their prevalence varied between groups and group members. Our analysis suggests that the types of interactions that were most common depended on the relative content knowledge of the group members as well as on the difficulty of the tasks in which they were engaged. Additionally, we were interested in characterizing the reasoning methods used by students within their study groups. We found that students used a combination of three content-relevant methods of reasoning: model-based reasoning, case-based reasoning, or rule-based reasoning, in conjunction with one chemically-irrelevant method of reasoning: symbol-based reasoning. The most common way for groups to reason was to use rules, whereas the least common way was for students to work from a model. In general, student reasoning correlated strongly to the subject matter to which students were paying attention, and was only weakly related to student interactions. Overall, results from this study may help instructors to construct appropriate tasks to guide what and how students study outside of the classroom. We found that students had a decidedly strategic approach in their study groups, relying heavily on material provided by their instructors, and using the reasoning strategies that resulted in the lowest levels of content processing. We suggest
Children's discomfort in assessments using different methods for approximal caries detection
Directory of Open Access Journals (Sweden)
Tatiane Fernandes Novaes
2012-04-01
Full Text Available Because discomfort caused by different approximal caries detection methods can influence their performance, the assessment of this discomfort is important. Thus, this study aimed to evaluate the discomfort reported by children after the use of different diagnostic methods to detect approximal caries lesions in primary teeth: visual inspection, bitewing radiography, laser fluorescence (DIAGNOdent pen - LFpen and temporary separation with orthodontic rubbers. Seventy-six children aged 4 to 12 years were examined using these methods. Their discomfort was assessed using the Wong-Baker scale and compared among the methods. Visual inspection caused less discomfort than did other methods. Radiography and the LFpen presented similar levels of discomfort. Older children reported higher discomfort using temporary separation, whereas younger children reported less discomfort with the LFpen. In conclusion, radiographic, temporary separation and LFpen methods provoke higher discomfort than visual inspection.
Terui, Akira
2010-01-01
We present an extension of our GPGCD method, an iterative method for calculating approximate greatest common divisor (GCD) of univariate polynomials, to polynomials with the complex coefficients. For a given pair of polynomials and a degree, our algorithm finds a pair of polynomials which has a GCD of the given degree and whose coefficients are perturbed from those in the original inputs, making the perturbations as small as possible, along with the GCD. In our GPGCD method, the problem of approximate GCD is transfered to a constrained minimization problem, then solved with a so-called modified Newton method, which is a generalization of the gradient-projection method, by searching the solution iteratively. While our original method is designed for polynomials with the real coefficients, we extend it to accept polynomials with the complex coefficients in this paper.
GPGCD, an Iterative Method for Calculating Approximate GCD, for Multiple Univariate Polynomials
Terui, Akira
2010-01-01
We present an extension of our GPGCD method, an iterative method for calculating approximate greatest common divisor (GCD) of univariate polynomials, to multiple polynomial inputs. For a given pair of polynomials and a degree, our algorithm finds a pair of polynomials which has a GCD of the given degree and whose coefficients are perturbed from those in the original inputs, making the perturbations as small as possible, along with the GCD. In our GPGCD method, the problem of approximate GCD is transferred to a constrained minimization problem, then solved with the so-called modified Newton method, which is a generalization of the gradient-projection method, by searching the solution iteratively. In this paper, we extend our method to accept more than two polynomials with the real coefficients as an input.
GPGCD, an Iterative Method for Calculating Approximate GCD, for Multiple Univariate Polynomials
Terui, Akira
We present an extension of our GPGCD method, an iterative method for calculating approximate greatest common divisor (GCD) of univariate polynomials, to multiple polynomial inputs. For a given pair of polynomials and a degree, our algorithm finds a pair of polynomials which has a GCD of the given degree and whose coefficients are perturbed from those in the original inputs, making the perturbations as small as possible, along with the GCD. In our GPGCD method, the problem of approximate GCD is transferred to a constrained minimization problem, then solved with the so-called modified Newton method, which is a generalization of the gradient-projection method, by searching the solution iteratively. In this paper, we extend our method to accept more than two polynomials with the real coefficients as an input.
Algebraic multilevel iteration methods and the best approximation to $1/x$ in the uniform norm
Kraus, Johannes; Zikatanov, Ludmil
2010-01-01
In this note, we provide simple convergence analysis for the algebraic multilevel iteration methods. We consider two examples of AMLI methods with different polynomial acceleration. The first one is based on shifted and scaled Chebyshev polynomial and the other on the polynomial of best approximation to $x^{-1}$ on a finite interval with positive endpoints in the uniform norm. The construction of the latter polynomial is of interest by itself, and we have included a derivation of a 3 term recurrence relation for computing this polynomial. We have also derived several inequalities related to the error of best approximation, which we applied in the AMLI analysis.
Laplace transform homotopy perturbation method for the approximation of variational problems.
Filobello-Nino, U; Vazquez-Leal, H; Rashidi, M M; Sedighi, H M; Perez-Sesma, A; Sandoval-Hernandez, M; Sarmiento-Reyes, A; Contreras-Hernandez, A D; Pereyra-Diaz, D; Hoyos-Reyes, C; Jimenez-Fernandez, V M; Huerta-Chua, J; Castro-Gonzalez, F; Laguna-Camacho, J R
2016-01-01
This article proposes the application of Laplace Transform-Homotopy Perturbation Method and some of its modifications in order to find analytical approximate solutions for the linear and nonlinear differential equations which arise from some variational problems. As case study we will solve four ordinary differential equations, and we will show that the proposed solutions have good accuracy, even we will obtain an exact solution. In the sequel, we will see that the square residual error for the approximate solutions, belongs to the interval [0.001918936920, 0.06334882582], which confirms the accuracy of the proposed methods, taking into account the complexity and difficulty of variational problems.
A New General Algebraic Method and Its Application to Shallow Long Wave Approximate Equations
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
A new general algebraic method is presented to uniformly construct a series of exact solutions for nonlinear evolution equations (NLEEs). For illustration, we apply the new method to shallow long wave approximate equations and successfully obtain abundant new exact solutions, which include rational solitary wave solutions and rational triangular periodic wave solutions. The method is straightforward and concise, and it can also be applied to other nonlinear evolution equations in mathematical physics.
Institute of Scientific and Technical Information of China (English)
Dongyang Shi; Haihong Wang; Yuepeng Du
2009-01-01
An anisotropic nonconforming finite element method is presented for a class of nonlinear Sobolev equations. The optimal error estimates and supercloseness are obtained for both semi-discrete and fully-discrete approximate schemes, which are the same as the traditional finite element methods. In addition, the global superconvergence is derived through the postprocessing technique. Numerical experiments are included to illustrate the feasibility of the proposed method.
A New Trigonometric Method of Summation and its Application to the Degree of Approximation
Indian Academy of Sciences (India)
G Das; Anasuya Nath; B K Ray
2002-05-01
The object of the present investigation is to introduce a new trigonometric method of summation which is both regular and Fourier effective and determine its status with reference to other methods of summation (see $\\mathcal{x}$2–$\\mathcal{x}$4) and also give an application of this method to determine the degree of approximation in a new Banach space of functions conceived as a generalized Hölder metric (see $\\mathcal{x}$5).
On the Influence of New Media and Methods to Achieve Reasonable Spread
Institute of Scientific and Technical Information of China (English)
胡海燕
2016-01-01
The emergence of new media not only accelerates the spread of information and brings convenience to people, but also subtly changes every aspect of people's life.This paper aims to discuss the influences that the new media bring for people and the methods that can achieve reasonable spread. All of us have the responsibility and obligation to achieve reasonable spread and make the new media serve better for the human progress.
Who is this person? A comparison study of current three-dimensional facial approximation methods.
Decker, Summer; Ford, Jonathan; Davy-Jow, Stephanie; Faraut, Philippe; Neville, Wesley; Hilbelink, Don
2013-06-10
Facial approximation is a common tool utilised in forensic human identification. Three-dimensional (3D) imaging technologies allow researchers to go beyond traditional clay models to now create virtual computed models of anatomical structures. The goal of this study was to compare the accuracy of available methods of facial approximation ranging from clay modelling to advanced computer facial approximation techniques. Two computerised reconstructions (FaceIT and FBI's ReFace) and two manual reconstructions (completed by FBI's Neville and Faraut) were completed using a skull from a known individual. A living individual's computed tomography (CT) scan was used to create a virtual 3D model of the skull and soft tissue of the face. The virtual skull models were provided to the computer-based approximation specialists. A rapid prototype of the skull was printed and provided to the practitioners who needed physical specimens. The results from all of the methods (clay and virtual) were compared visually to each other and collectively to the actual features of the living individual to compare the results of each. A quantitative study was also conducted to establish the accuracy of each method and the regions of the face that need the most improvement for all of the specialists. This project demonstrates the wide range of variation between commonly used facial identification methods. The benefit of this study was having a living individual to test the strengths and weaknesses of each method while also providing future areas of focus for soft tissue depth data studies. PMID:23628365
A decision method based on uncertainty reasoning of linguistic truth-valued concept lattice
Yang, Li; Xu, Yang
2010-04-01
Decision making with linguistic information is a research hotspot now. This paper begins by establishing the theory basis for linguistic information processing and constructs the linguistic truth-valued concept lattice for a decision information system, and further utilises uncertainty reasoning to make the decision. That is, we first utilise the linguistic truth-valued lattice implication algebra to unify the different kinds of linguistic expressions; second, we construct the linguistic truth-valued concept lattice and decision concept lattice according to the concrete decision information system and third, we establish the internal and external uncertainty reasoning methods and talk about the rationality of them. We apply these uncertainty reasoning methods into decision making and present some generation methods of decision rules. In the end, we give an application of this decision method by an example.
An Approximate Method for the Surge Response of the Tension Leg Platform
Institute of Scientific and Technical Information of China (English)
Rahim Shoghi; Mohammad Reza Tabeshpour
2014-01-01
The solution for the Duffing equation in a nonlinear vibration problem is studied in this paper. Clearly, in the case of the perturb parameter being a larger value, the traditional perturbation method is no longer valid but the Homotopy Perturbation Method (HPM) is applicable usually. HPM is used to solve the weak and strong nonlinear differential equations for finding the perturbed frequency of the response. The obtained frequencies via HPM and the approximate method have good accordance for weak and strong nonlinear differential equations. Additionally, the calculated responses by use of the approximate method are compared with the responses obtained from the Numerical method in the time history of the response and phase plane. The results represent good accordance between them.
Higher order analytical approximate solutions to the nonlinear pendulum by He's homotopy method
Energy Technology Data Exchange (ETDEWEB)
Belendez, A; Pascual, C; Alvarez, M L; Mendez, D I; Yebra, M S; Hernandez, A [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es
2009-01-15
A modified He's homotopy perturbation method is used to calculate the periodic solutions of a nonlinear pendulum. The method has been modified by truncating the infinite series corresponding to the first-order approximate solution and substituting a finite number of terms in the second-order linear differential equation. As can be seen, the modified homotopy perturbation method works very well for high values of the initial amplitude. Excellent agreement of the analytical approximate period with the exact period has been demonstrated not only for small but also for large amplitudes A (the relative error is less than 1% for A < 152 deg.). Comparison of the result obtained using this method with the exact ones reveals that this modified method is very effective and convenient.
Global collocation methods for approximation and the solution of partial differential equations
Solomonoff, A.; Turkel, E.
1986-01-01
Polynomial interpolation methods are applied both to the approximation of functions and to the numerical solutions of hyperbolic and elliptic partial differential equations. The derivative matrix for a general sequence of the collocation points is constructed. The approximate derivative is then found by a matrix times vector multiply. The effects of several factors on the performance of these methods including the effect of different collocation points are then explored. The resolution of the schemes for both smooth functions and functions with steep gradients or discontinuities in some derivative are also studied. The accuracy when the gradients occur both near the center of the region and in the vicinity of the boundary is investigated. The importance of the aliasing limit on the resolution of the approximation is investigated in detail. Also examined is the effect of boundary treatment on the stability and accuracy of the scheme.
Aptitude treatment effects of laboratory grouping method for students of differing reasoning ability
Lawrenz, Frances; Munch, Theodore W.
This study examines aptitude treatment effects in an inquiry/learning cycle based physical science class for elementary education majors. The aptitude was formal reasoning ability and the students were arranged into three groups: high, middle, and low ability reasoners. The treatment was method of forming groups to work in the laboratory. Students in each of three classes were grouped according to reasoning ability. In one class the laboratory groups were homogeneous, i.e., students of similar reasoning ability were grouped together. In the second class the students were grouped heterogeneously, i.e., students of different reasoning ability were grouped together. In the third class, the student choice pattern, the students chose their own partners. The findings were that there were no aptitude treatment interaction for achievement or for gain in formal reasoning ability, that grouping students of similar cognitive ability together for laboratory work in the class was more effective in terms of science achievement than grouping students of differing cognitive ability together or than allowing students to choose their own partners, and that students at different levels of reasoning ability experienced differential gains in that ability over the semester.
12 CFR 717.25 - Reasonable and simple methods of opting out.
2010-01-01
... CREDIT UNIONS FAIR CREDIT REPORTING Affiliate Marketing § 717.25 Reasonable and simple methods of opting... an Internet Web site, if the consumer agrees to the electronic delivery of information; (iv... the Act, and the affiliate marketing opt-out under the Act, by a single method, such as by calling...
Approximation to the Mean and Variance of Moments Method Estimate Due to Gamma Distribution
International Nuclear Information System (INIS)
In this paper, we shall consider the approximation to the mean and variance of moments method estimators due to gamma distribution by using Taylor series expansion approach.This approach showed that the estimators are asymptotically unbiased with mean square error approach zero as the sample size approach infinity.The theoretical approach assessed practically by using Monte-Carlo simulation
The information-based complexity of approximation problem by adaptive Monte Carlo methods
Institute of Scientific and Technical Information of China (English)
2008-01-01
In this paper, we study the complexity of information of approximation problem on the multivariate Sobolev space with bounded mixed derivative MWpr,α(Td), 1 < p < ∞, in the norm of Lq(Td), 1 < q < ∞, by adaptive Monte Carlo methods. Applying the discretization technique and some properties of pseudo-s-scale, we determine the exact asymptotic orders of this problem.
Viscosity Approximation Method for Infinitely Many Asymptotically Nonexpansive Maps in Banach Spaces
Institute of Scientific and Technical Information of China (English)
Ruo Feng RAO
2011-01-01
In the framework of reflexive Banach spaces satisfying a weakly continuous duality map,the author uses the viscosity approximation method to obtain the strong convergence theorem for iterations with infinitely many asymptotically nonexpansive mappings.The main results obtained in this paper improve and extend some recent results.
Astudillo, R.; Van Gijzen, M.B.
2014-01-01
A new algorithm to compute eigenpairs of large unsymmetric matrices is presented. Using the Induced Dimension Reduction method (IDR), which was originally proposed for solving linear systems, we obtain a Hessenberg decomposition from which we approximate the eigen-values and eigenvectors of a matrix
Approximation and inference methods for stochastic biochemical kinetics - a tutorial review
Schnoerr, David; Grima, Ramon
2016-01-01
Stochastic fluctuations of molecule numbers are ubiquitous in biological systems. Important examples include gene expression and enzymatic processes in living cells. Such systems are typically modelled as chemical reaction networks whose dynamics are governed by the Chemical Master Equation. Despite its simple structure, no analytic solutions to the Chemical Master Equation are known for most systems. Moreover, stochastic simulations are computationally expensive, making systematic analysis and statistical inference a challenging task. Consequently, significant effort has been spent in recent decades on the development of efficient approximation and inference methods. This article gives an introduction to basic modelling concepts as well as an overview of state of the art methods. First, we motivate and introduce deterministic and stochastic models for chemical networks, and give an overview of simulation and exact solution methods. Next, we discuss several approximation methods, including the chemical Langev...
New finite volume methods for approximating partial differential equations on arbitrary meshes
International Nuclear Information System (INIS)
This dissertation presents some new methods of finite volume type for approximating partial differential equations on arbitrary meshes. The main idea lies in solving twice the problem to be dealt with. One addresses the elliptic equations with variable (anisotropic, antisymmetric, discontinuous) coefficients, the parabolic linear or non linear equations (heat equation, radiative diffusion, magnetic diffusion with Hall effect), the wave type equations (Maxwell, acoustics), the elasticity and Stokes'equations. Numerous numerical experiments show the good behaviour of this type of method. (author)
Debrabant, Kristian; Rößler, Andreas
2013-01-01
In the present paper, a class of stochastic Runge-Kutta methods containing the second order stochastic Runge-Kutta scheme due to E. Platen for the weak approximation of It\\^o stochastic differential equation systems with a multi-dimensional Wiener process is considered. Order one and order two conditions for the coefficients of explicit stochastic Runge-Kutta methods are solved and the solution space of the possible coefficients is analyzed. A full classification of the coefficients for such ...
On approximation of nonlinear boundary integral equations for the combined method
Energy Technology Data Exchange (ETDEWEB)
Gregus, M.; Khoromsky, B.N.; Mazurkevich, G.E.; Zhidkov, E.P.
1989-09-22
The nonlinear boundary integral equations that arise in research of nonlinear magnetostatic problems are investigated in combined formulation on an unbounded domain. Approximations of the derived operator equations are studied based on the Galerkin method. The investigated boundary operators are strongly monotone, Lipschitz-continuous, potential and have a symmetrical Gateaux derivative. The error estimates of the Galerkin's approximation in Sobolev spaces of fractional powers are obtained using the above-mentioned properties of the operators, too. The problem has been studied on surfaces in two and three-dimensional spaces. We answer also some questions on convergence connected with the discretized systems of equations. 21 refs.
Adomian Decomposition Method and Padé Approximants for Nonlinear Differential-Difference Equations
Institute of Scientific and Technical Information of China (English)
LIU Yan-Ming; CHEN Yong
2009-01-01
Combining Adomian decomposition method (ADM) with Padd approximants, we solve two differential-difference equations (DDEs): the relativistic Toda lattice equation and the modified Volterra lattice equation.With the help of symbolic computation Maple, the results obtained by ADM-Padé technique are compared with those obtained by using ADM alone.The numerical results demonstrate that ADM-Padé technique give the approximate solution with faster convergence rate and higher accuracy and relative in larger domain of convergence than using ADM.
A meshless Galerkin method with moving least square approximations for infinite elastic solids
Institute of Scientific and Technical Information of China (English)
Li Xiao-Lin; Li Shu-Ling
2013-01-01
Combining moving least square approximations and boundary integral equations,a meshless Galerkin method,which is the Galerkin boundary node method (GBNM),for two-and three-dimensional infinite elastic solid mechanics problems with traction boundary conditions is discussed.In this numerical method,the resulting formulation inherits the symmetry and positive definiteness of variational problems,and boundary conditions can be applied directly and easily.A rigorous error analysis and convergence study for both displacement and stress is presented in Sobolev spaces.The capability of this method is illustrated and assessed by some numerical examples.
Directory of Open Access Journals (Sweden)
M. P. Menguc
2011-09-01
Full Text Available We embark on this preliminary study of the suitability of the discrete dipole approximation with surface interaction (DDA-SI method to model electric field scattering from noble metal nano-structures on dielectric substrates. The refractive index of noble metals, particularly due to their high imaginary components, require smaller lattice spacings and are especially sensitive to the shape integrity and the volume of the dipole model. The results of DDA-SI method are validated against those of the well-established finite element method (FEM and the finite difference time domain (FDTD method.
A Scalable Method for Solving High-Dimensional Continuous POMDPs Using Local Approximation
Erez, Tom
2012-01-01
Partially-Observable Markov Decision Processes (POMDPs) are typically solved by finding an approximate global solution to a corresponding belief-MDP. In this paper, we offer a new planning algorithm for POMDPs with continuous state, action and observation spaces. Since such domains have an inherent notion of locality, we can find an approximate solution using local optimization methods. We parameterize the belief distribution as a Gaussian mixture, and use the Extended Kalman Filter (EKF) to approximate the belief update. Since the EKF is a first-order filter, we can marginalize over the observations analytically. By using feedback control and state estimation during policy execution, we recover a behavior that is effectively conditioned on incoming observations despite the unconditioned planning. Local optimization provides no guarantees of global optimality, but it allows us to tackle domains that are at least an order of magnitude larger than the current state-of-the-art. We demonstrate the scalability of ...
Adomian decomposition method and Padè approximants for solving the Blaszak-Marciniak lattice
Institute of Scientific and Technical Information of China (English)
YangPei; Chen Yong; Li Zhi-Bin
2008-01-01
The Adomian decomposition method (ADM) and Padè approximants are combined to solve the well-known Blaszak-Marciniak lattice,which has rich mathematical structures and many important applications in physics and mathematics.In some cases,the truncated series solution of ADM is adequate only in a small region when the exact solution is not reached.To overcome the drawback,the Padè approximants,which have the advantage in turning the polynomials approximation into a rational function,are applied to the series solution to improve the accuracy and enlarge the convergence domain.By using the ADM-Padè technique,the soliton solutions of the Blaszak-Marciniak lattice are constructed with better accuracy and better convergence than by using the ADM alone.Numerical and figurative illustrations show that it is a promising tool for solving nonlinear problems.
Parallel Preconditioned Conjugate Gradient Square Method Based on Normalized Approximate Inverses
Directory of Open Access Journals (Sweden)
George A. Gravvanis
2005-01-01
Full Text Available A new class of normalized explicit approximate inverse matrix techniques, based on normalized approximate factorization procedures, for solving sparse linear systems resulting from the finite difference discretization of partial differential equations in three space variables are introduced. A new parallel normalized explicit preconditioned conjugate gradient square method in conjunction with normalized approximate inverse matrix techniques for solving efficiently sparse linear systems on distributed memory systems, using Message Passing Interface (MPI communication library, is also presented along with theoretical estimates on speedups and efficiency. The implementation and performance on a distributed memory MIMD machine, using Message Passing Interface (MPI is also investigated. Applications on characteristic initial/boundary value problems in three dimensions are discussed and numerical results are given.
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
For structural system with random basic variables as well as fuzzy basic variables,uncertain propagation from two kinds of basic variables to the response of the structure is investigated.A novel algorithm for obtaining membership function of fuzzy reliability is presented with saddlepoint approximation(SA)based line sampling method.In the presented method,the value domain of the fuzzy basic variables under the given membership level is firstly obtained according to their membership functions.In the value domain of the fuzzy basic variables corresponding to the given membership level,bounds of reliability of the structure response satisfying safety requirement are obtained by employing the SA based line sampling method in the reduced space of the random variables.In this way the uncertainty of the basic variables is propagated to the safety measurement of the structure,and the fuzzy membership function of the reliability is obtained.Compared to the direct Monte Carlo method for propagating the uncertainties of the fuzzy and random basic variables,the presented method can considerably improve computational efficiency with acceptable precision.The presented method has wider applicability compared to the transformation method,because it doesn’t limit the distribution of the variable and the explicit expression of performance function, and no approximation is made for the performance function during the computing process.Additionally,the presented method can easily treat the performance function with cross items of the fuzzy variable and the random variable,which isn’t suitably approximated by the existing transformation methods.Several examples are provided to illustrate the advantages of the presented method.
Simple and fast cosine approximation method for computer-generated hologram calculation.
Nishitsuji, Takashi; Shimobaba, Tomoyoshi; Kakue, Takashi; Arai, Daisuke; Ito, Tomoyoshi
2015-12-14
The cosine function is a heavy computational operation in computer-generated hologram (CGH) calculation; therefore, it is implemented by substitution methods such as a look-up table. However, the computational load and required memory space of such methods are still large. In this study, we propose a simple and fast cosine function approximation method for CGH calculation. As a result, we succeeded in creating CGH with sufficient quality and made the calculation time 1.6 times as fast at maximum compared to using the look-up table of the cosine function on CPU implementation.
Born approximation to a perturbative numerical method for the solution of the Schroedinger equation
International Nuclear Information System (INIS)
A step function perturbative numerical method (SF-PN method) is developed for the solution of the Cauchy problem for the second order liniar differential equation in normal form. An important point stressed in the present paper, which seems to have been previously ignored in the literature devoted to the PN methods, is the close connection between the first order perturbation theory of the PN approach and the wellknown Born approximation, and, in general, the connection between the varjous orders of the PN corrections and the Neumann series. (author)
Non-consistent approximations of self-adjoint eigenproblems: Application to the supercell method
Cancès, Eric; Maday, Yvon
2012-01-01
In this article, we introduce a general theoretical framework to analyze non-consistent approximations of the discrete eigenmodes of a self-adjoint operator. We focus in particular on the discrete eigenvalues laying in spectral gaps. We first provide a priori error estimates on the eigenvalues and eigenvectors in the absence of spectral pollution. We then show that the supercell method for perturbed periodic Schr\\"odinger operators falls into the scope of our study. We prove that this method is spectral pollution free, and we derive optimal convergence rates for the planewave discretization method, taking numerical integration errors into account. Some numerical illustrations are provided.
Approximate Explicit Solution of Falkner-Skan Equation by Homotopy Perturbation Method
Directory of Open Access Journals (Sweden)
N. Moallemi
2012-08-01
Full Text Available In this study, by mean`s of He`s Homotopy Perturbation Method (HPM an approximate solution of Falkner-Skan equation obtained. In boundary layer theory, we have seen how similarity methods combine two independent variables into one, and therefore our problems our simplified to ODE Equations. If we use HPM we can deforms a difficult ordinary differential equation into a simple problem which can be easily solved. Comparison is made between the solution of Falkner Skan equation for 4 cases and those in open literature to verify accuracy of this work. Results show that the method is very effective and simple.
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Simulation of borehole induction using the hybrid extended Born approximation and CG-FFHT method
Zhang, Zhong Qing; Liu, Qing Huo
2000-07-01
We propose the hybridization of the extended Born approximation (EBA) with the conjugate-gradient fast Fourier Hankel transform (CG-FFHT) method to improve the efficiency of numerical solution of borehole induction problems in axisymmetric media. First, we use the FFHT to accelerate the EBA as a nonlinear approximation to induction problems, resulting in an algorithm with O(N log2 N) arithmetic operations, where N is the number of unknowns in the problem. This improved EBA is accurate for most formations encountered. Then, for formations with extremely high contrasts, we utilize this improved EBA as a partial preconditioner in the CG-FFHT method to solve the problem accurately with few iterations. The seamless combination of these two approaches provides an automatic way toward the efficient and accurate modeling of induction measurements in axisymmetric media.
A Resampling-Based Stochastic Approximation Method for Analysis of Large Geostatistical Data
Liang, Faming
2013-03-01
The Gaussian geostatistical model has been widely used in modeling of spatial data. However, it is challenging to computationally implement this method because it requires the inversion of a large covariance matrix, particularly when there is a large number of observations. This article proposes a resampling-based stochastic approximation method to address this challenge. At each iteration of the proposed method, a small subsample is drawn from the full dataset, and then the current estimate of the parameters is updated accordingly under the framework of stochastic approximation. Since the proposed method makes use of only a small proportion of the data at each iteration, it avoids inverting large covariance matrices and thus is scalable to large datasets. The proposed method also leads to a general parameter estimation approach, maximum mean log-likelihood estimation, which includes the popular maximum (log)-likelihood estimation (MLE) approach as a special case and is expected to play an important role in analyzing large datasets. Under mild conditions, it is shown that the estimator resulting from the proposed method converges in probability to a set of parameter values of equivalent Gaussian probability measures, and that the estimator is asymptotically normally distributed. To the best of the authors\\' knowledge, the present study is the first one on asymptotic normality under infill asymptotics for general covariance functions. The proposed method is illustrated with large datasets, both simulated and real. Supplementary materials for this article are available online. © 2013 American Statistical Association.
A New Newton's Method with Diagonal Jacobian Approximation for Systems of Nonlinear Equations
Directory of Open Access Journals (Sweden)
M. Y. Waziri
2010-01-01
Full Text Available Problem statement: The major weaknesses of Newton method for nonlinear equations entail computation of Jacobian matrix and solving systems of n linear equations in each of the iterations. Approach: In some extent function derivatives are quit costly and Jacobian is computationally expensive which requires evaluation (storage of n×n matrix in every iteration. Results: This storage requirement became unrealistic when n becomes large. We proposed a new method that approximates Jacobian into diagonal matrix which aims at reducing the storage requirement, computational cost and CPU time, as well as avoiding solving n linear equations in each iterations. Conclusion/Recommendations: The proposed method is significantly cheaper than Newtons method and very much faster than fixed Newtons method also suitable for small, medium and large scale nonlinear systems with dense or sparse Jacobian. Numerical experiments were carried out which shows that, the proposed method is very encouraging.
An atmospheric backscatter model on wind measurements using far-field approximation method
Institute of Scientific and Technical Information of China (English)
SHU Weiping; ZHAO Zhengyu
2007-01-01
A backscatter model was developed for measuring wind field with the far-field approximation method.The theoretical computation and computer simulations with one spatial dimension show that this model can realistically describe the physical meaning and process of the three methods in wind measurements including the spaced antenna (SA) method,Doppler beam swing (DBS) method,and spaced interferometry (SI).The computational difficulties of the traditional theoretical model cannot only be smoothed away,but common characteristics and differences of the three methods can be compared deeply.The comparison of the numerical results between the Wuhan medium frequency (MF) radar (30° N,114° E) observation and the computer simulation of the full correlation analysis (FCA) of the SA method indicates that the two results agree very well and this model has practical application.
Institute of Scientific and Technical Information of China (English)
LongShuyao; HuDe'an
2003-01-01
The meshless method is a new numerical technique presented in recent years .It uses the moving least square (MLS) approximation as a shape function . The smoothness of the MLS approximation is determined by that of the basic function and of the weight function, and is mainly determined by that of the weight function. Therefore, the weight function greatly affects the accuracy of results obtained. Different kinds of weight functions, such as the spline function, the Gauss function and so on, are proposed recently by many researchers. In the present work, the features of various weight functions are illustrated through solving elasto-static problems using the local boundary integral equation method. The effect of various weight functions on the accuracy, convergence and stability of results obtained is also discussed. Examples show that the weight function proposed by Zhou Weiyuan and Gauss and the quartic spline weight function are better than the others if parameters c and a in Gauss and exponential weight functions are in the range of reasonable values, respectively, and the higher the smoothness of the weight function, the better the features of the solutions.
Negara, Ardiansyah
2013-01-01
Anisotropy of hydraulic properties of subsurface geologic formations is an essential feature that has been established as a consequence of the different geologic processes that they undergo during the longer geologic time scale. With respect to petroleum reservoirs, in many cases, anisotropy plays significant role in dictating the direction of flow that becomes no longer dependent only on the pressure gradient direction but also on the principal directions of anisotropy. Furthermore, in complex systems involving the flow of multiphase fluids in which the gravity and the capillarity play an important role, anisotropy can also have important influences. Therefore, there has been great deal of motivation to consider anisotropy when solving the governing conservation laws numerically. Unfortunately, the two-point flux approximation of finite difference approach is not capable of handling full tensor permeability fields. Lately, however, it has been possible to adapt the multipoint flux approximation that can handle anisotropy to the framework of finite difference schemes. In multipoint flux approximation method, the stencil of approximation is more involved, i.e., it requires the involvement of 9-point stencil for the 2-D model and 27-point stencil for the 3-D model. This is apparently challenging and cumbersome when making the global system of equations. In this work, we apply the equation-type approach, which is the experimenting pressure field approach that enables the solution of the global problem breaks into the solution of multitude of local problems that significantly reduce the complexity without affecting the accuracy of numerical solution. This approach also leads in reducing the computational cost during the simulation. We have applied this technique to a variety of anisotropy scenarios of 3-D subsurface flow problems and the numerical results demonstrate that the experimenting pressure field technique fits very well with the multipoint flux approximation
Approximations to the Probability of Failure in Random Vibration by Integral Equation Methods
DEFF Research Database (Denmark)
Nielsen, Søren R.K.; Sørensen, John Dalsgaard
Close approximations to the first passage probability of failure in random vibration can be obtained by integral equation methods. A simple relation exists between the first passage probability density function and the distribution function for the time interval spent below a barrier before outcr...... passage probability density. The results of the theory agree well with simulation results for narrow banded processes dominated by a single frequency, as well as for bimodal processes with 2 dominating frequencies in the structural response....
An approximate method for solving a melting problem with periodic boundary conditions
Qu Liang-Hui; Xing Lin; Yu Zhi-Yun; Ling Feng; Xu Jian-Guo
2014-01-01
An effective thermal diffusivity method is used to solve one-dimensional melting problem with periodic boundary conditions in a semi-infinite domain. An approximate analytic solution showing the functional relation between the location of the moving boundary and time is obtained by using Laplace transform. The evolution of the moving boundary and the temperature field in the phase change domain are simulated numerically, and the numerical results are compar...
A nodal method for solving the time-depending diffusion equation in the IQS approximation
International Nuclear Information System (INIS)
The fast and slow variation of the neutron flux shape needed for the dynamical description of nuclear reactor cores can be described advantageously in the Improved Quasistatic (IQS) model where the flux is factorized by a fast changing space-independent amplitude and a slow changing shape function. The basic equations of a time-dependent nodal approximation using the IQS method is presented.The calculational procedure of the response matrices is also described. (R.P.) 2 refs
An approximate method for solving a melting problem with periodic boundary conditions
Directory of Open Access Journals (Sweden)
Qu Liang-Hui
2014-01-01
Full Text Available An effective thermal diffusivity method is used to solve one-dimensional melting problem with periodic boundary conditions in a semi-infinite domain. An approximate analytic solution showing the functional relation between the location of the moving boundary and time is obtained by using Laplace transform. The evolution of the moving boundary and the temperature field in the phase change domain are simulated numerically, and the numerical results are compared with previous results in open literature.
A method for the accurate and smooth approximation of standard thermodynamic functions
Coufal, O.
2013-01-01
A method is proposed for the calculation of approximations of standard thermodynamic functions. The method is consistent with the physical properties of standard thermodynamic functions. This means that the approximation functions are, in contrast to the hitherto used approximations, continuous and smooth in every temperature interval in which no phase transformations take place. The calculation algorithm was implemented by the SmoothSTF program in the C++ language which is part of this paper. Program summaryProgram title:SmoothSTF Catalogue identifier: AENH_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3807 No. of bytes in distributed program, including test data, etc.: 131965 Distribution format: tar.gz Programming language: C++. Computer: Any computer with gcc version 4.3.2 compiler. Operating system: Debian GNU Linux 6.0. The program can be run in operating systems in which the gcc compiler can be installed, see http://gcc.gnu.org/install/specific.html. RAM: 256 MB are sufficient for the table of standard thermodynamic functions with 500 lines Classification: 4.9. Nature of problem: Standard thermodynamic functions (STF) of individual substances are given by thermal capacity at constant pressure, entropy and enthalpy. STF are continuous and smooth in every temperature interval in which no phase transformations take place. The temperature dependence of STF as expressed by the table of its values is for further application approximated by temperature functions. In the paper, a method is proposed for calculating approximation functions which, in contrast to the hitherto used approximations, are continuous and smooth in every temperature interval. Solution method: The approximation functions are
The reliability of approximate radiation transport methods for irradiated disk studies
Kuiper, Rolf
2013-01-01
Context: Dynamical studies of irradiated circumstellar disks require an accurate treatment of radiation transport to, for example, properly determine cooling and fragmentation properties. The radiation transport algorithm should be as fast as the (magneto-) hydrodynamics to allow for an efficient usage of computing resources. Methods: We use a setup of a central star and a slightly flared circumstellar disk. We perform simulations for a wide range of optical depths of the disk's midplane from tau(550nm) = 0.1 up to tau(810nm) = 1 million. We check the accuracy of the gray flux-limited diffusion (FLD) approximation and a gray and frequency-dependent ray-tracing plus FLD approximation. Results: 1. For moderate optical depths, a gray approximation of the stellar irradiation yields a slightly hotter inner rim and a slightly cooler midplane of the disk at larger radii, but is otherwise in agreement with the frequency-dependent treatment. 2. The gray FLD approximation fails to compute an appropriate temperature pro...
Application of asymptotic waveform approximation technique to hybrid FE/BI method for 3D scattering
Institute of Scientific and Technical Information of China (English)
PENG Zhen; SHENG XinQing
2007-01-01
The asymptotic waveform evaluation (AWE) technique is a rational function approximation method in computational mathematics, which is used in many applications in computational electromagnetics. In this paper, the performance of the AWE technique in conjunction with hybrid finite element/boundary integral (FE/BI) method is firstly investigated. The formulation of the AWE applied in hybrid FE/BI method is given in detail. The characteristic implementation of the application of the AWE to the hybrid FE/BI method is discussed. Numerical results demonstrate that the AWE technique can greatly speed up the hybrid FE/BI method to acquire wide-band and wide-angle backscatter radar-cross-section (RCS) by complex targets.
One Fairing Method of Cubic B-spline Curves Based on Weighted Progressive Iterative Approximation
Institute of Scientific and Technical Information of China (English)
ZHANG Li; YANG Yan; LI Yuan-yuan; TAN Jie-qing
2014-01-01
A new method to the problem of fairing planar cubic B-spline curves is introduced in this paper. The method is based on weighted progressive iterative approximation (WPIA for short) and consists of following steps:finding the bad point which needs to fair, deleting the bad point, re-inserting a new data point to keep the structure of the curve and applying WPIA method with the new set of the data points to obtain the faired curve. The new set of the data points is formed by the rest of the original data points and the new inserted point. The method can be used for shape design and data processing. Numerical examples are provided to demonstrate the effectiveness of the method.
Approximation-Exact Penalty Function Method for Solving a Class of Stochastic Programming
Institute of Scientific and Technical Information of China (English)
Wang Guang-min; Wan Zhong-ping
2003-01-01
We present an approximation-exact penalty function method for solving the single stage stochastic programming problem with continuous random variable. The original problem is transformed into a determinate nonlinear programming problem with a discrete random variable sequence, which is obtained by some discrete method. We construct an exact penalty function and obtain an unconstrained optimization. It avoids the difficulty in solution by the rapid growing of the number of constraints for discrete precision. Under lenient conditions, we prove the equivalence of the minimum solution of penalty function and the solution of the determinate programming, and prove that the solution sequences of the discrete problem converge to a solution to the original problem.
Directory of Open Access Journals (Sweden)
Halim CEYLAN
2007-02-01
Full Text Available This study develops approximate mathematical expressions for delay components at signalized intersections. Delay components are solved with the coordinate transformation method. The performance indicators for the signalized intersection are determined as an oversaturated and under saturated cases. During the analysis, the steady-state and the deterministic queuing theory are investigated first, and then time-dependent transformation is made. Developed model, called YHM, is applied to an example signalized intersection. Results are compared with the current situation and the Webster method. YHM is improved the intersection performance by about 500 % for this example. Moreover, signal parameters are significantly differs from the current and Webster signal control.
Approximation by random weighting method for M-test in linear models
Institute of Scientific and Technical Information of China (English)
2007-01-01
The M-test has been in common use and widely studied in testing the linear hypotheses in linear models. However, the critical value for the test is usually related to the quantities of the unknown error distribution and the estimate of the nuisance parameters may be rather involved, not only for the M-test method but also for the existing bootstrap methods. In this paper we suggest a random weighting resampling method for approximating the null distribution of the M-test statistic. It is shown that, under both the null and the local alternatives, the random weighting statistic has the same asymptotic distribution as the null distribution of the M-test. The critical values of the M-test can therefore be obtained by the random weighting method without estimating the nuisance parameters. A distinguished feature of the proposed method is that the approximation is valid even the null hypothesis is not true and the power evaluation is possible under the local alternatives.
The approximate inversion as a reconstruction method in X-ray computerized tomography
Dietz, R L
1999-01-01
The mathematical model of the X-ray computerized tomography will be developed in the first chapter, the approximate inversion will be introduced, and the Radon Transform will be used as an example to demonstrate calculation of a reconstruction cone. In the second chapter, a reconstruction method for the parallel geometry is discussed, leading to derivation of the method for a fan-beam geometry. The approximate inversion calculated for the limited-angle case is presented as an example of incomplete data problems. As with complete data problems, numerical examples are given and the method is compared with existing other methods. 3D reconstruction is the topic of the third chapter. Although of no relevance in practice, a parallel geometry will be examined. No problems are encountered in transferring the reconstruction cone to the cone beam geometry, but only for a scanning curve which also is of no relevance in practice. A further reconstruction method is presented for curves fulfilling the so-called Tuy conditi...
New identification method for Hammerstein models based on approximate least absolute deviation
Xu, Bao-Chang; Zhang, Ying-Dan
2016-07-01
Disorder and peak noises or large disturbances can deteriorate the identification effects of Hammerstein non-linear models when using the least-square (LS) method. The least absolute deviation technique can be used to resolve this problem; however, its absolute value cannot meet the need of differentiability required by most algorithms. To improve robustness and resolve the non-differentiable problem, an approximate least absolute deviation (ALAD) objective function is established by introducing a deterministic function that exhibits the characteristics of absolute value under certain situations. A new identification method for Hammerstein models based on ALAD is thus developed in this paper. The basic idea of this method is to apply the stochastic approximation theory in the process of deriving the recursive equations. After identifying the parameter matrix of the Hammerstein model via the new algorithm, the product terms in the matrix are separated by calculating the average values. Finally, algorithm convergence is proven by applying the ordinary differential equation method. The proposed algorithm has a better robustness as compared to other LS methods, particularly when abnormal points exist in the measured data. Furthermore, the proposed algorithm is easier to apply and converges faster. The simulation results demonstrate the efficacy of the proposed algorithm.
S-curve networks and an approximate method for estimating degree distributions of complex networks
International Nuclear Information System (INIS)
In the study of complex networks almost all theoretical models have the property of infinite growth, but the size of actual networks is finite. According to statistics from the China Internet IPv4 (Internet Protocol version 4) addresses, this paper proposes a forecasting model by using S curve (logistic curve). The growing trend of IPv4 addresses in China is forecasted. There are some reference values for optimizing the distribution of IPv4 address resource and the development of IPv6. Based on the laws of IPv4 growth, that is, the bulk growth and the finitely growing limit, it proposes a finite network model with a bulk growth. The model is said to be an S-curve network. Analysis demonstrates that the analytic method based on uniform distributions (i.e., Barabási-Albert method) is not suitable for the network. It develops an approximate method to predict the growth dynamics of the individual nodes, and uses this to calculate analytically the degree distribution and the scaling exponents. The analytical result agrees with the simulation well, obeying an approximately power-law form. This method can overcome a shortcoming of Barabási-Albert method commonly used in current network research. (general)
Approximation by random weighting method for M-test in linear models
Institute of Scientific and Technical Information of China (English)
Xiao-yan WU; Ya-ning YANG; Lin-cheng ZHAO
2007-01-01
The M-test has been in common use and widely studied in testing the linear hypotheses in linear models. However, the critical value for the test is usually related to the quantities of the unknown error distribution and the estimate of the nuisance parameters may be rather involved, not only for the M-test method but also for the existing bootstrap methods. In this paper we suggest a random weighting resampling method for approximating the null distribution of the M-test statistic.It is shown that, under both the null and the local alternatives, the random weighting statistic has the same asymptotic distribution as the null distribution of the M-test. The critical values of the M-test can therefore be obtained by the random weighting method without estimating the nuisance parameters. A distinguished feature of the proposed method is that the approximation is valid even the null hypothesis is not true and the power evaluation is possible under the local alternatives.
International Nuclear Information System (INIS)
Highlights: • The complex quantum Hamilton–Jacobi equation is approximately solved in real space. • Equations of motion are derived through use of the derivative propagation method. • Numerically unstable reflected trajectories may pass through the potential barrier. • Transmitted wave packet is obtained by propagating individual Bohmian trajectories. • Excellent transmission probabilities are obtained for both thick and thin barriers. - Abstract: The complex quantum Hamilton–Jacobi equation for the complex action is approximately solved by propagating individual Bohmian trajectories in real space. Equations of motion for the complex action and its spatial derivatives are derived through use of the derivative propagation method. We transform these equations into the arbitrary Lagrangian–Eulerian version with the grid velocity matching the flow velocity of the probability fluid. Setting higher-order derivatives equal to zero, we obtain a truncated system of equations of motion describing the rate of change in the complex action and its spatial derivatives transported along approximate Bohmian trajectories. A set of test trajectories is propagated to determine appropriate initial positions for transmitted trajectories. Computational results for transmitted wave packets and transmission probabilities are presented and analyzed for a one-dimensional Eckart barrier and a two-dimensional system involving either a thick or thin Eckart barrier along the reaction coordinate coupled to a harmonic oscillator
Energy Technology Data Exchange (ETDEWEB)
Chou, Chia-Chun, E-mail: ccchou@mx.nthu.edu.tw
2015-08-18
Highlights: • The complex quantum Hamilton–Jacobi equation is approximately solved in real space. • Equations of motion are derived through use of the derivative propagation method. • Numerically unstable reflected trajectories may pass through the potential barrier. • Transmitted wave packet is obtained by propagating individual Bohmian trajectories. • Excellent transmission probabilities are obtained for both thick and thin barriers. - Abstract: The complex quantum Hamilton–Jacobi equation for the complex action is approximately solved by propagating individual Bohmian trajectories in real space. Equations of motion for the complex action and its spatial derivatives are derived through use of the derivative propagation method. We transform these equations into the arbitrary Lagrangian–Eulerian version with the grid velocity matching the flow velocity of the probability fluid. Setting higher-order derivatives equal to zero, we obtain a truncated system of equations of motion describing the rate of change in the complex action and its spatial derivatives transported along approximate Bohmian trajectories. A set of test trajectories is propagated to determine appropriate initial positions for transmitted trajectories. Computational results for transmitted wave packets and transmission probabilities are presented and analyzed for a one-dimensional Eckart barrier and a two-dimensional system involving either a thick or thin Eckart barrier along the reaction coordinate coupled to a harmonic oscillator.
A new method for extraction of approximately vertical lines from natural images
Institute of Scientific and Technical Information of China (English)
赵建坤; 吴江华; 张田文
2002-01-01
For natural images with complex background and noise, this new approach appears is more effective than other techniques for three key reasons: 1)edge elements treated interdependently to overcome the weakness of standard Hough transform (HT); 2)gradient orientation information taken into account in the process of HT; 3) an effective method used to "merge" the HT result, i.e. many "clustered short lines" into single straight line to represent the edge of object to be recognized. This method consists of three steps are: 1) edge detection; 2)modified Hough transform to extract "clustered short lines"; 3) merging "clustered short lines" into a single line after few modifications. The method presented in this paper could also be used for extraction of non-vertical straight lines.
Optimal motion planning of an underactuated spacecraft using wavelet approximate method
Institute of Scientific and Technical Information of China (English)
GE Xinsheng; CHEN Liqun; LIU Yanzhu
2006-01-01
An optimal motion planning scheme using wavelet approximation is proposed for an underactuated spacecraft. The motion planning of an underactuated spacecraft can be formulated as an optimal control of a drift-free system. A cost functional is used to incorporate the control energy and the final state errors. The motion planning is to determine control inputs to minimize the cost functional.Using the method of wavelet, one can transform an infinite-dimensional optimal control problem to a finite-dimensional one and use GaussNewton algorithm to solve it for a feasible trajectory which satisfies nonholonomic constraints. The proposed scheme has been applied to a rigid spacecraft with two momentum wheels. The numerical simulation results indicate that optimal control with wavelet approximation is an effective approach to steering an underactuated spacecraft system from the initial configuration to the final configuration.
The Wentzel-Kramers-Brillouin approximation method applied to the Wigner function
Tosiek, J.; Cordero, R.; Turrubiates, F. J.
2016-06-01
An adaptation of the Wentzel-Kramers-Brilluoin method in the deformation quantization formalism is presented with the aim to obtain an approximate technique of solving the eigenvalue problem for energy in the phase space quantum approach. A relationship between the phase σ ( r →) of a wave function exp (" separators=" /i ħ σ ( r →)) and its respective Wigner function is derived. Formulas to calculate the Wigner function of a product and of a superposition of wave functions are proposed. Properties of a Wigner function of interfering states are also investigated. Examples of this quasi-classical approximation in deformation quantization are analysed. A strict form of the Wigner function for states represented by tempered generalised functions has been derived. Wigner functions of unbound states in the Poeschl-Teller potential have been found.
Potential function methods for approximately solving linear programming problems theory and practice
Bienstock, Daniel
2002-01-01
Potential Function Methods For Approximately Solving Linear Programming Problems breaks new ground in linear programming theory. The book draws on the research developments in three broad areas: linear and integer programming, numerical analysis, and the computational architectures which enable speedy, high-level algorithm design. During the last ten years, a new body of research within the field of optimization research has emerged, which seeks to develop good approximation algorithms for classes of linear programming problems. This work both has roots in fundamental areas of mathematical programming and is also framed in the context of the modern theory of algorithms. The result of this work, in which Daniel Bienstock has been very much involved, has been a family of algorithms with solid theoretical foundations and with growing experimental success. This book will examine these algorithms, starting with some of the very earliest examples, and through the latest theoretical and computational developments.
Approximate-model Based Estimation Method for Dynamic Response of Forging Processes
Institute of Scientific and Technical Information of China (English)
LEI Jie; LU Xinjiang; LI Yibo; HUANG Minghui; ZOU Wei
2015-01-01
Many high-quality forging productions require the large-sized hydraulic press machine (HPM) to have a desirable dynamic response. Since the forging process is complex under the low velocity, its response is difficult to estimate. And this often causes the desirable low-velocity forging condition difficult to obtaln. So far little work has been found to estimate the dynamic response of the forging process under low velocity. In this paper, an approximate-model based estimation method is proposed to estimate the dynamic response of the forging process under low velocity. First, an approximate model is developed to represent the forging process of this complex HPM around the low-velocity working point. Under guaranteeing the modeling performance, the model may greatly ease the complexity of the subsequent estimation of the dynamic response because it has a good linear structure. On this basis, the dynamic response is estimated and the conditions for stability, vibration, and creep are derived according to the solution of the velocity. All these analytical results are further verified by both simulations and experiment. In the simulation verification for modeling, the original movement model and the derived approximate model always have the same dynamic responses with very small approximate error. The simulations and experiment finally demonstrate and test the effectiveness of the derived conditions for stability, vibration, and creep, and these conditions will benefit both the prediction of the dynamic response of the forging process and the design of the controller for the high-quality forging. The proposed method is an effective solution to achieve the desirable low-velocity forging condition.
Wu, Fuke; Tian, Tianhai; Rawlings, James B; Yin, George
2016-05-01
The frequently used reduction technique is based on the chemical master equation for stochastic chemical kinetics with two-time scales, which yields the modified stochastic simulation algorithm (SSA). For the chemical reaction processes involving a large number of molecular species and reactions, the collection of slow reactions may still include a large number of molecular species and reactions. Consequently, the SSA is still computationally expensive. Because the chemical Langevin equations (CLEs) can effectively work for a large number of molecular species and reactions, this paper develops a reduction method based on the CLE by the stochastic averaging principle developed in the work of Khasminskii and Yin [SIAM J. Appl. Math. 56, 1766-1793 (1996); ibid. 56, 1794-1819 (1996)] to average out the fast-reacting variables. This reduction method leads to a limit averaging system, which is an approximation of the slow reactions. Because in the stochastic chemical kinetics, the CLE is seen as the approximation of the SSA, the limit averaging system can be treated as the approximation of the slow reactions. As an application, we examine the reduction of computation complexity for the gene regulatory networks with two-time scales driven by intrinsic noise. For linear and nonlinear protein production functions, the simulations show that the sample average (expectation) of the limit averaging system is close to that of the slow-reaction process based on the SSA. It demonstrates that the limit averaging system is an efficient approximation of the slow-reaction process in the sense of the weak convergence. PMID:27155630
Rossi, Mariana; Paesani, Francesco; Bowman, Joel; Ceriotti, Michele
2014-01-01
Including quantum mechanical effects on the dynamics of nuclei in the condensed phase is challenging, because the complexity of exact methods grows exponentially with the number of quantum degrees of freedom. Efforts to circumvent these limitations can be traced down to two approaches: methods that treat a small subset of the degrees of freedom with rigorous quantum mechanics, considering the rest of the system as a static or classical environment, and methods that treat the whole system quantum mechanically, but using approximate dynamics. Here we perform a systematic comparison between these two philosophies for the description of quantum effects in vibrational spectroscopy, taking the Embedded Local Monomer (LMon) model and a mixed quantum-classical (MQC) model as representatives of the first family of methods, and centroid molecular dynamics (CMD) and thermostatted ring polymer molecular dynamics (TRPMD) as examples of the latter. We use as benchmarks D$_2$O doped with HOD and pure H$_2$O at three distinc...
A novel approximation method of CTF amplitude correction for 3D single particle reconstruction
International Nuclear Information System (INIS)
The typical resolution of three-dimensional reconstruction by cryo-EM single particle analysis is now being pushed up to and beyond the nanometer scale. Correction of the contrast transfer function (CTF) of electron microscopic images is essential for achieving such a high resolution. Various correction methods exist and are employed in popular reconstruction software packages. Here, we present a novel approximation method that corrects the amplitude modulation introduced by the contrast transfer function by convoluting the images with a piecewise continuous function. Our new approach can easily be implemented and incorporated into other packages. The implemented method yielded higher resolution reconstructions with data sets from both highly symmetric and asymmetric structures. It is an efficient alternative correction method that allows quick convergence of the 3D reconstruction and has a high tolerance for noisy images, thus easing a bottleneck in practical reconstruction of macromolecules.
Anda, E.; Chiappe, G.; Busser, C.; Davidovich, M.; Martins, G.; H-Meisner, F.; Dagotto, E.
2008-03-01
A numerical algorithm to study transport properties of highly correlated local structures is proposed. The method, dubbed the Logarithmic Discretization Embedded Cluster Approximation (LDECA), consists of diagonalizing a finite cluster containing the many-body terms of the Hamiltonian and embedding it into the rest of the system, combined with Wilson's ideas of a logarithmic discretization of the representation of the Hamiltonian. LDECA's rapid convergence eliminates finite-size effects commonly present in the embedding cluster approximation (ECA) method. The physics associated with both one embedded dot and a string of two dots side-coupled to leads is discussed. In the former case, our results accurately agree with Bethe ansatz (BA) data, while in the latter, the results are framed in the conceptual background of a two-stage Kondo problem. A diagrammatic expansion provides the theoretical foundation for the method. It is argued that LDECA allows for the study of complex problems that are beyond the reach of currently available numerical methods.
Semantic Ontology Method of Learning Resource based on the Approximate Subgraph Isomorphism
Directory of Open Access Journals (Sweden)
Lili Zhang
2014-02-01
Full Text Available Digital learning resource ontology is often based on different specification building. It is hard to find resources by linguistic ontology matching method. The existing structural matching method fails to solve the problem of calculation of structural similarity well. For the heterogeneity problem among learning resource ontology, an algorithm is presented based on subgraph approximate isomorphism. First of all, we can preprocess the resource of clustering algorithm through the semantic analysis, then describe the ontology by the directed graph and calculate the similarity, and finally judge the semantic relations through calculating and analyzing different resource between the ontology of different learning resource to achieve semantic compatibility or mapping of ontology. This method is an extension of existing methods in ontology matching. Under the comprehensive application of features such as edit distance and hierarchical relations, the similarity of graph structures between two ontologies is calculated. And, the ontology matching is determined on the condition of subgraph approximate isomorphism based on the alternately mapping of nodes and arcs in the describing graphs of ontologies. An example is used to demonstrate this ontology matching process and the time complexity is analyzed to explain its effectiveness
Directory of Open Access Journals (Sweden)
M. Scherstjanoi
2013-09-01
Full Text Available Models of vegetation dynamics that are designed for application at spatial scales larger than individual forest gaps suffer from several limitations. Typically, either a population average approximation is used that results in unrealistic tree allometry and forest stand structure, or models have a high computational demand because they need to simulate both a series of age-based cohorts and a number of replicate patches to account for stochastic gap-scale disturbances. The detail required by the latter method increases the number of calculations by two to three orders of magnitude compared to the less realistic population average approach. In an effort to increase the efficiency of dynamic vegetation models without sacrificing realism, we developed a new method for simulating stand-replacing disturbances that is both accurate and faster than approaches that use replicate patches. The GAPPARD (approximating GAP model results with a Probabilistic Approach to account for stand Replacing Disturbances method works by postprocessing the output of deterministic, undisturbed simulations of a cohort-based vegetation model by deriving the distribution of patch ages at any point in time on the basis of a disturbance probability. With this distribution, the expected value of any output variable can be calculated from the output values of the deterministic undisturbed run at the time corresponding to the patch age. To account for temporal changes in model forcing (e.g., as a result of climate change, GAPPARD performs a series of deterministic simulations and interpolates between the results in the postprocessing step. We integrated the GAPPARD method in the vegetation model LPJ-GUESS, and evaluated it in a series of simulations along an altitudinal transect of an inner-Alpine valley. We obtained results very similar to the output of the original LPJ-GUESS model that uses 100 replicate patches, but simulation time was reduced by approximately the factor 10
Approximate restoration of translational and rotational symmetries within the Lipkin method
Gao, Y; Toivanen, P
2015-01-01
Background: Nuclear self-consistent mean-field approaches are rooted in the density functional theory and, through the spontaneous symmetry breaking mechanism, allow for including important correlations, while keeping the simplicity of the approach. Because real ground states should have all symmetries of the nuclear Hamiltonian, these methods require subsequent symmetry restoration. Purpose: We implement and study Lipkin method of approximate variation after projection applied to the restoration of the translational or rotational symmetries. Methods: We use Lipkin operators up to quadratic terms in momenta or angular momenta with self-consistently determined values of the Peierls-Yoccoz translational masses or moments of inertia, respectively. Calculations based on Skyrme energy-density functional are performed for heavy, deformed, and paired nuclei. Results: In deformed nuclei, the Peierls-Yoccoz translational masses along three different principal-axes directions of the intrinsic system can be different, w...
The Financial Impact of Risk Factors Affecting Project Cost Contingency: Evidential Reasoning Method
Emmanuel Abeere-Inga; Joseph Ignatius Teye Buertey; Theophilus Adjei Kumi
2013-01-01
The process of cost modeling using risk analysis for construction projects is very crucial for the achievement of project success. The purpose of this paper is to present an analysis of the financial impact of risk factors affecting key construction work sections; using a systematic risk methodology based on empirical judgment. The failure mode effect analysis (FMEA) and the evidential reasoning methods are presented as qualitative and quantitative risk tools respectively. Data analysis from ...
DEFF Research Database (Denmark)
Eriksen, Janus Juul; Solanko, Lukasz Michal; Nåbo, Lina J.;
2014-01-01
We present an implementation of the Polarizable Continuum Model (PCM) in combination with the Second–Order Polarization Propagator Approximation (SOPPA) electronic structure method. In analogy with the most common way of designing ground state calculations based on a Second–Order Møller-Plesset (MP...... functional theory employing a range-separated exchange-correlation functional, we find the PCM-SOPPA/RPA approach to be slightly superior with respect to systematicity. On the other hand, the absolute values of the predicted excitation energies are largely underestimated. This – however – is a well...
Bieg, Bohdan; Chrzanowski, Janusz; Kravtsov, Yury A.; Orsitto, Francesco
Basic principles and recent findings of quasi-isotropic approximation (QIA) of a geometrical optics method are presented in a compact manner. QIA was developed in 1969 to describe electromagnetic waves in weakly anisotropic media. QIA represents the wave field as a power series in two small parameters, one of which is a traditional geometrical optics parameter, equal to wavelength ratio to plasma characteristic scale, and the other one is the largest component of anisotropy tensor. As a result, "" QIA ideally suits to tokamak polarimetry/interferometry systems in submillimeter range, where plasma manifests properties of weakly anisotropic medium.
Directory of Open Access Journals (Sweden)
Yang Zhiwei
2010-01-01
Full Text Available We propose a subspace-tracking-based space-time adaptive processing technique for airborne radar applications. By applying a modified approximated power iteration subspace tracing algorithm, the principal subspace in which the clutter-plus-interference reside is estimated. Therefore, the moving targets are detected by projecting the data on the minor subspace which is orthogonal to the principal subspace. The proposed approach overcomes the shortcomings of the existing methods and has satisfactory performance. Simulation results confirm that the performance improvement is achieved at very small secondary sample support, a feature that is particularly attractive for applications in heterogeneous environments.
Niksic, Tamara; Tutis, Tea; Vretenar, Dario; Ring, Peter
2013-01-01
A new implementation of the finite amplitude method (FAM) for the solution of the relativistic quasiparticle random-phase approximation (RQRPA) is presented, based on the relativistic Hartree-Bogoliubov (RHB) model for deformed nuclei. The numerical accuracy and stability of the FAM -- RQRPA is tested in a calculation of the monopole response of $^{22}$O. As an illustrative example, the model is applied to a study of the evolution of monopole strength in the chain of Sm isotopes, including the splitting of the giant monopole resonance in axially deformed systems.
A Method for Generating Approximate Similarity Solutions of Nonlinear Partial Differential Equations
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Mazhar Iqbal
2014-01-01
Full Text Available Standard application of similarity method to find solutions of PDEs mostly results in reduction to ODEs which are not easily integrable in terms of elementary or tabulated functions. Such situations usually demand solving reduced ODEs numerically. However, there are no systematic procedures available to utilize these numerical solutions of reduced ODE to obtain the solution of original PDE. A practical and tractable approach is proposed to deal with such situations and is applied to obtain approximate similarity solutions to different cases of an initial-boundary value problem of unsteady gas flow through a semi-infinite porous medium.
Non-approximate method for designing annular field of two-mirror concentric system
Institute of Scientific and Technical Information of China (English)
Yuanshen Huang; Dongyue Zhu; Baicheng Li; Dawei Zhang; Zhengji Ni; Songlin Zhuang
2012-01-01
Annular field aberrations of a three-reflection concentric system, which are composed of two spherical mirrors, are analyzed. An annular field with a high level of aberration correction exists near the position where the principal ray is perpendicular to the object-image plane. Aberrations are determined by the object height and aperture angle. In this letter, the general expression of the system aberration is derived using the geometric method, and the non-approximate design method is proposed to calculate the radii of the annular fields that have minimum aberrations under different aperture angles. The closer to 0.5 (the ratio of the radius of convex mirror to the radius of concave mirror) is, the smaller the system aberration is. The examples analyzed by LABVIEW indicate that the annular field designed by the proposed method has the smallest aberration in a given system.%Annular field aberrations of a three-reflection concentric system,which are composed of two spherical mirrors,are analyzed.An annular field with a high level of aberration correction exists near the position where the principal ray is perpendicular to the object-image plane.Aberrations are determined by the object height and aperture angle.In this letter,the general expression of the system aberration is derived using the geometric method,and the non-approximate design method is proposed to calculate the radii of the annular fields that have minimum aberrations under different aperture angles.The closer to 0.5 (the ratio of the radius of convex mirror to the radius of concave mirror) is,the smaller the system aberration is.The examples analyzed by LABVIEW indicate that the annular field designed by the proposed method has the smallest aberration in a given system.
Sakamoto, Noboru; Schaft, Arjan J. van der
2007-01-01
In this paper, an analytical approximation approach for the stabilizing solution of the Hamilton-Jacobi equation using stable manifold theory is proposed. The proposed method gives approximated flows on the stable manifold of the associated Hamiltonian system and provides approximations of the stabl
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Between the transformations, witch can transform the compressible wave equation to the incompressible flow, a kind of relativity character can be found, which have the almost equal character as Lorenz time and space relation. This result leads to a new inference: incompressible wave equation with time and space structure of sonic special relativity is only different description of approximate compressible flow. This conclusion can be extended to Euler equation, and arise the interest of "compressible expression" of Maxwell equation. To study the rule of compressibility and thermodynamic character of metastructure field, a try is made by the using KamanTsian virtual gas method, this would give the relation,similar as mass and energy of special relativity theory.At first searching a transformation, witch can transform the compressible wave equation to the incompressible flow, but it is almost equal Lorenz time and space relation, So arrive to the conclusion: incompressible wave equation with approximate Lorentz transformation is only different description of compressible flow. This conclusion is expected be used to Maxwell equation, because its wave equation is also perfectly equal form. To search the rule of electromagnet and gravity field, by the using of Kaman-Tsian virtual gas method, the relation of mass and energy of relativity theory is given.``
On the optimal polynomial approximation of stochastic PDEs by galerkin and collocation methods
Beck, Joakim
2012-09-01
In this work we focus on the numerical approximation of the solution u of a linear elliptic PDE with stochastic coefficients. The problem is rewritten as a parametric PDE and the functional dependence of the solution on the parameters is approximated by multivariate polynomials. We first consider the stochastic Galerkin method, and rely on sharp estimates for the decay of the Fourier coefficients of the spectral expansion of u on an orthogonal polynomial basis to build a sequence of polynomial subspaces that features better convergence properties, in terms of error versus number of degrees of freedom, than standard choices such as Total Degree or Tensor Product subspaces. We consider then the Stochastic Collocation method, and use the previous estimates to introduce a new class of Sparse Grids, based on the idea of selecting a priori the most profitable hierarchical surpluses, that, again, features better convergence properties compared to standard Smolyak or tensor product grids. Numerical results show the effectiveness of the newly introduced polynomial spaces and sparse grids. © 2012 World Scientific Publishing Company.
AGCD:a robust periodicity analysis method based on approximate greatest common divisor
Institute of Scientific and Technical Information of China (English)
Juan YU‡; Pei-zhong LU
2015-01-01
Periodicity is one of the most common phenomena in the physical world. The problem of periodicity analysis (or period detection) is a research topic in several areas, such as signal processing and data mining. However, period detection is a very challenging problem, due to the sparsity and noisiness of observational datasets of periodic events. This paper focuses on the problem of period detection from sparse and noisy observational datasets. To solve the problem, a novel method based on the approximate greatest common divisor (AGCD) is proposed. The proposed method is robust to sparseness and noise, and is eﬃcient. Moreover, unlike most existing methods, it does not need prior knowledge of the rough range of the period. To evaluate the accuracy and eﬃciency of the proposed method, comprehensive experiments on synthetic data are conducted. Experimental results show that our method can yield highly accurate results with small datasets, is more robust to sparseness and noise, and is less sensitive to the magnitude of period than compared methods.
Communication: An efficient analytic gradient theory for approximate spin projection methods
Hratchian, Hrant P.
2013-03-01
Spin polarized and broken symmetry density functional theory are popular approaches for treating the electronic structure of open shell systems. However, spin contamination can significantly affect the quality of predicted geometries and properties. One scheme for addressing this concern in studies involving broken-symmetry states is the approximate projection method developed by Yamaguchi and co-workers. Critical to the exploration of potential energy surfaces and the study of properties using this method will be an efficient analytic gradient theory. This communication introduces such a theory formulated, for the first time, within the framework of general post-self consistent field (SCF) derivative theory. Importantly, the approach taken here avoids the need to explicitly solve for molecular orbital derivatives of each nuclear displacement perturbation, as has been used in a recent implementation. Instead, the well-known z-vector scheme is employed and only one SCF response equation is required.
Approximation-Exact Penalty Function Method for Solving a Class of Stochastic Programming
Institute of Scientific and Technical Information of China (English)
WangGuang-min; WanZhong-ping
2003-01-01
We present an approximation-exact penalty function method for solving the single stage stochastic programming problem with continuous random variable. The original problem is transformed into a determinate nonlinear programming problem with a discrete random variable sequence, which is obtained by some discrete method. We construct an exact penalty function and obtain an unconstrained optimization. It avoids the difficulty in solution by the rapid growing of the number of constraints for discrete precision.Under lenient conditions, we prove the equivalence of the minimum solution of penalty function and the solution of the determinate programming, and prove that the solution sequences of the discrete problem converge to a solution to the original problem.
About the Generalized Reasoning Methods and their Use in Semiotic Systems
Directory of Open Access Journals (Sweden)
Mihaela I. MUNTEAN
2006-01-01
Full Text Available In computational semiotics the problem is to emulate a semiosis cycle within a digital computer. This needs the construction of intelligent systems, able to perform intelligent behavior, such as sensorial perception, world modeling, value judgement and behavior generation. These intelligent systems could be generally implemented through object networks and the basic functions mentioned above could be obtained by generalization of some elementary knowledge operators. Based on the three main reasoning methods, deduction, induction and abduction, well known in the philosophy of science and used in AI systems, there were three knew knowledge operators defined: knowledge extraction, knowledge generation and knowledge generation, operators that could be viewed as generalized interpretations of the standard reasoning procedures. This paper presents these new concepts and their connection, the current understanding of generalized deduction, induction and abduction and also how these operators could serve as the building blocks of universal intelligent systems.
Kaporin, I. E.
2012-02-01
In order to precondition a sparse symmetric positive definite matrix, its approximate inverse is examined, which is represented as the product of two sparse mutually adjoint triangular matrices. In this way, the solution of the corresponding system of linear algebraic equations (SLAE) by applying the preconditioned conjugate gradient method (CGM) is reduced to performing only elementary vector operations and calculating sparse matrix-vector products. A method for constructing the above preconditioner is described and analyzed. The triangular factor has a fixed sparsity pattern and is optimal in the sense that the preconditioned matrix has a minimum K-condition number. The use of polynomial preconditioning based on Chebyshev polynomials makes it possible to considerably reduce the amount of scalar product operations (at the cost of an insignificant increase in the total number of arithmetic operations). The possibility of an efficient massively parallel implementation of the resulting method for solving SLAEs is discussed. For a sequential version of this method, the results obtained by solving 56 test problems from the Florida sparse matrix collection (which are large-scale and ill-conditioned) are presented. These results show that the method is highly reliable and has low computational costs.
Frantz, Eric Randall
Elongation and shaping of the tokamak plasma cross -section can allow increased beta and other favorable improvements. As the cross-section is made non-circular, however, the plasma can become unstable against axisymmetric motions, the most predominant one being a nearly uniform displacement in the direction of elongation. Without additional stabilizing mechanisms, this instability has growth rates typically (TURN)10('6)sec('-1). With passive and active feedback from external conductors, the plasma can be significantly slowed down and controlled. In this work, a mathematical formulism for analyzing the vertical instability is developed in which the external conductors are treated (or broken -up) as discrete coils. The circuit equations for the plasma induced currents can be included within the same mathematical framework. The plasma equation of motion and the circuit equations are combined and manipulated into a diagonalized form that can be graphically analyzed to determine the growth rate. An effective mode approximation (EMA) to the dispersion relation in introduced to simplify and approximate the growth rate of the more exact case. Controller voltage equations for active feedback are generalized to include position and velocity feedback and time delay. A position cut-off displacement is added to model finite spatial resolution of the position detectors or a dead-band voltage level. Stability criteria are studied for EMA and the more exact case. The time dependent responses for plasma position controller voltages, and currents are determined from the Laplace transformations. Slow responses are separated from the fast ones (dependent on plasma inertia) using a typical tokamak ordering approximation. The methods developed are applied in numerous examples for the machine geometry and plasma of TNS, an inside-D configuration plasma resembling JET, INTOR, or FED.
Jiang, Lijian
2009-10-02
The use of limited global information in multiscale simulations is needed when there is no scale separation. Previous approaches entail fine-scale simulations in the computation of the global information. The computation of the global information is expensive. In this paper, we propose the use of approximate global information based on partial upscaling. A requirement for partial homogenization is to capture long-range (non-local) effects present in the fine-scale solution, while homogenizing some of the smallest scales. The local information at these smallest scales is captured in the computation of basis functions. Thus, the proposed approach allows us to avoid the computations at the scales that can be homogenized. This results in coarser problems for the computation of global fields. We analyze the convergence of the proposed method. Mathematical formalism is introduced, which allows estimating the errors due to small scales that are homogenized. The proposed method is applied to simulate two-phase flows in heterogeneous porous media. Numerical results are presented for various permeability fields, including those generated using two-point correlation functions and channelized permeability fields from the SPE Comparative Project (Christie and Blunt, SPE Reserv Evalu Eng 4:308-317, 2001). We consider simple cases where one can identify the scales that can be homogenized. For more general cases, we suggest the use of upscaling on the coarse grid with the size smaller than the target coarse grid where multiscale basis functions are constructed. This intermediate coarse grid renders a partially upscaled solution that contains essential non-local information. Numerical examples demonstrate that the use of approximate global information provides better accuracy than purely local multiscale methods. © 2009 Springer Science+Business Media B.V.
The effect of method and format on the responses of subjects to a Piagetian reasoning problem
Staver, John R.; Pascarella, Ernest T.
Researchers interested in studying the effects of subjects' reasoning levels, as defined by Piaget (Inhelder & Piaget, 1958), on science achievement or other dependent variables face two measurement problems. First, the traditional clinical method is time-consuming and impractical for large numbers of subjects. Second, alternative methods of assessment, although reliable and valid, may over- or underestimate subjects' reasoning levels. The objective of this investigation was to determine the effects of various methods and formats of administering a Piagetian task on subjects' performance. The task chosen for this investigation was the Mr. Short-Mr. Tall problem (Karplus & Lavatelli, 1969; Karplus et al., 1977). The task was presented using four methods: (1) individual clinical interview, (2) group presentation of task followed by paper-and-pencil problem with illustration, (3) group administration of paper-and-pencil instrument with illustration, and (4) group administration of paper-and-pencil instrument without illustration. Each method included four formats: (1) completion answer with essay justification, (2) completion answer with multiple-choice justification, (3) multiple-choice answer with essay justification, and (4) multiple-choice answer with multiple-choice justification. Three hundred seventy-six students who were enrolled in a freshman level biological science class participated in the study. The research design was a 4 × 4 factorial design with method and format of assessment as the main effects. The participants were in 16 distinct laboratory or discussion sections, and each section was randomly assigned to a cell in the research design. Regression analysis with the individual as the unit of analysis showed that neither method nor format of assessment accounted for a significant amount of variance in student performance. The overall interaction remained nonsignificant. Regression analysis with sections as the unit of analysis revealed similar
Approximate analytic method for high-apogee twelve-hour orbits of artificial Earth's satellites
Vashkovyaka, M. A.; Zaslavskii, G. S.
2016-09-01
We propose an approach to the study of the evolution of high-apogee twelve-hour orbits of artificial Earth's satellites. We describe parameters of the motion model used for the artificial Earth's satellite such that the principal gravitational perturbations of the Moon and Sun, nonsphericity of the Earth, and perturbations from the light pressure force are approximately taken into account. To solve the system of averaged equations describing the evolution of the orbit parameters of an artificial satellite, we use both numeric and analytic methods. To select initial parameters of the twelve-hour orbit, we assume that the path of the satellite along the surface of the Earth is stable. Results obtained by the analytic method and by the numerical integration of the evolving system are compared. For intervals of several years, we obtain estimates of oscillation periods and amplitudes for orbital elements. To verify the results and estimate the precision of the method, we use the numerical integration of rigorous (not averaged) equations of motion of the artificial satellite: they take into account forces acting on the satellite substantially more completely and precisely. The described method can be applied not only to the investigation of orbit evolutions of artificial satellites of the Earth; it can be applied to the investigation of the orbit evolution for other planets of the Solar system provided that the corresponding research problem will arise in the future and the considered special class of resonance orbits of satellites will be used for that purpose.
Coherent-potential approximation in the tight-binding linear muffin-tin orbital method
Energy Technology Data Exchange (ETDEWEB)
Singh, P.P.; Gonis, A. (Chemistry and Materials Science Department, L-268, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))
1993-07-15
We describe a consistent approach for applying the coherent-potential approximation (CPA) to the various representations of the linear muffin-tin orbital method. Unlike the previous works of Kudrnovsky [ital et] [ital al]. [Phys. Rev. B 35, 2487 (1987); 41, 7515 (1990)], our results for the ensemble-averaged Green functions in the tight-binding representation yield [ital E]- and [bold r]-dependent quantities that are consistent with the traditional applications of the single-site CPA. To illustrate the reliability and the usefulness of our approach we compare the nonspherically averaged charge densities, calculated in real space, of ordered NiPt in [ital L]1[sub 0] structure and the substitutionally disordered Ni[sub 0.5]Pt[sub 0.5] on a face-centered-cubic lattice.
An extragradient-like approximation method for variational inequalities and fixed point problems
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Wong Ngai-Ching
2011-01-01
Full Text Available Abstract The purpose of this paper is to investigate the problem of finding a common element of the set of fixed points of an asymptotically strict pseudocontractive mapping in the intermediate sense and the set of solutions of a variational inequality problem for a monotone and Lipschitz continuous mapping. We introduce an extragradient-like iterative algorithm that is based on the extragradient-like approximation method and the modified Mann iteration process. We establish a strong convergence theorem for two sequences generated by this extragradient-like iterative algorithm. Utilizing this theorem, we also design an iterative process for finding a common fixed point of two mappings, one of which is an asymptotically strict pseudocontractive mapping in the intermediate sense and the other taken from the more general class of Lipschitz pseudocontractive mappings. 1991 MSC: 47H09; 47J20.
Diffusion approximation-based simulation of stochastic ion channels: which method to use?
Directory of Open Access Journals (Sweden)
Danilo ePezo
2014-11-01
Full Text Available To study the effects of stochastic ion channel fluctuations on neural dynamics, several numerical implementation methods have been proposed. Gillespie’s method for Markov Chains (MC simulation is highly accurate, yet it becomes computationally intensive in the regime of high channel numbers. Many recent works aim to speed simulation time using the Langevin-based Diffusion Approximation (DA. Under this common theoretical approach, each implementation differs in how it handles various numerical difficulties – such as bounding of state variables to [0,1]. Here we review and test a set of the most recently published DA implementations (Dangerfield et al., 2012; Linaro et al., 2011; Huang et al., 2013a; Orio and Soudry, 2012; Schmandt and Galán, 2012; Goldwyn et al., 2011; Güler, 2013, comparing all of them in a set of numerical simulations that asses numerical accuracy and computational efficiency on three different models: the original Hodgkin and Huxley model, a model with faster sodium channels, and a multi-compartmental model inspired in granular cells. We conclude that for low channel numbers (usually below 1000 per simulated compartment one should use MC – which is both the most accurate and fastest method. For higher channel numbers, we recommend using the method by Orio and Soudry (2012, possibly combined with the method by Schmandt and Galán (2012 for increased speed and slightly reduced accuracy. Consequently, MC modelling may be the best method for detailed multicompartment neuron models – in which a model neuron with many thousands of channels is segmented into many compartments with a few hundred channels.
Diffusion approximation-based simulation of stochastic ion channels: which method to use?
Pezo, Danilo; Soudry, Daniel; Orio, Patricio
2014-01-01
To study the effects of stochastic ion channel fluctuations on neural dynamics, several numerical implementation methods have been proposed. Gillespie's method for Markov Chains (MC) simulation is highly accurate, yet it becomes computationally intensive in the regime of a high number of channels. Many recent works aim to speed simulation time using the Langevin-based Diffusion Approximation (DA). Under this common theoretical approach, each implementation differs in how it handles various numerical difficulties—such as bounding of state variables to [0,1]. Here we review and test a set of the most recently published DA implementations (Goldwyn et al., 2011; Linaro et al., 2011; Dangerfield et al., 2012; Orio and Soudry, 2012; Schmandt and Galán, 2012; Güler, 2013; Huang et al., 2013a), comparing all of them in a set of numerical simulations that assess numerical accuracy and computational efficiency on three different models: (1) the original Hodgkin and Huxley model, (2) a model with faster sodium channels, and (3) a multi-compartmental model inspired in granular cells. We conclude that for a low number of channels (usually below 1000 per simulated compartment) one should use MC—which is the fastest and most accurate method. For a high number of channels, we recommend using the method by Orio and Soudry (2012), possibly combined with the method by Schmandt and Galán (2012) for increased speed and slightly reduced accuracy. Consequently, MC modeling may be the best method for detailed multicompartment neuron models—in which a model neuron with many thousands of channels is segmented into many compartments with a few hundred channels. PMID:25404914
Edwards, Kyle T
2014-07-01
In recent years, liberal democratic societies have struggled with the question of how best to balance expertise and democratic participation in the regulation of emerging technologies. This study aims to explain how national deliberative ethics committees handle the practical tension between scientific expertise, ethical expertise, expert patient input, and lay public input by explaining two institutions' processes for determining the legitimacy or illegitimacy of reasons in public policy decision-making: that of the United Kingdom's Human Fertilisation and Embryology Authority (HFEA) and the United States' American Society for Reproductive Medicine (ASRM). The articulation of these 'methods of legitimation' draws on 13 in-depth interviews with HFEA and ASRM members and staff conducted in January and February 2012 in London and over Skype, as well as observation of an HFEA deliberation. This study finds that these two institutions employ different methods in rendering certain arguments legitimate and others illegitimate: while the HFEA attempts to 'balance' competing reasons but ultimately legitimizes arguments based on health and welfare concerns, the ASRM seeks to 'filter' out arguments that challenge reproductive autonomy. The notably different structures and missions of each institution may explain these divergent approaches, as may what Sheila Jasanoff (2005) terms the distinctive 'civic epistemologies' of the US and the UK. Significantly for policy makers designing such deliberative committees, each method differs substantially from that explicitly or implicitly endorsed by the institution.
Marušić, Mirko; Sliško, Josip
2012-01-01
The Lawson Classroom Test of Scientific Reasoning (LCTSR) was used to gauge the relative effectiveness of three different methods of pedagogy, Reading, Presenting, and Questioning (RPQ), Experimenting and Discussion (ED), and Traditional Methods (TM), on increasing students' level of scientific thinking. The data of a one-semester-long senior high-school project indicate that, for the LCTSR: (a) the RPQ group (n = 91) achieved effect-sizes d = 0.30 and (b) the ED group (n = 85) attained effect-sizes d = 0.64. These methods have shown that the Piagetian and Vygotskian visions on learning and teaching can go hand in hand and as such achieve respectable results. To do so, it is important to challenge the students and thus encourage the shift towards higher levels of reasoning. This aim is facilitated through class management which recognizes the importance of collaborative learning. Carrying out Vygotsky's original intention to use teaching to promote cognitive development as well as subject concepts, this research has shown that it is better to have students experience cognitive conflict from directly observed experiments than by reflecting on reported experience from popularization papers or writings found on the internet.
International Nuclear Information System (INIS)
Objective: To summarize the reasons of bleeding complications and the prevention methods in stenting for intracranial arterial stenosis. Methods: The clinical data of 366 patients underwent stent-assistant angioplasty of intracranial artery stenosis from July 2006 to December 2011 were analyzed retrospectively. Among them, 14 patients with bleeding complications were found. The initial 100 patients were categorized as early stage group and the rest as mature stage group. The reasons of bleeding and the methods for preventing this complication were summarized. Results: The overall incidence of bleeding complication was 3.8% (14/366). In the early stage group and mature stage group,the rates was 10%(10/100) and 1.5% (4/266). Six cases were related to the operational manipulation and 8 cases secondary to hyperperfusion injury. Death was found in 6 patients,severe disability in 3, mild paralysis in 2, and no neurological deficits in 3. Conclusions: The bleeding complications in stent-assisted angioplasty of intracranial artery stenosis have a high disability and mortality. The improvement of operative techniques and the more strict indications decrease the bleeding complications rate effectively. (authors)
Linguistic hesitant fuzzy multi-criteria decision-making method based on evidential reasoning
Zhou, Huan; Wang, Jian-qiang; Zhang, Hong-yu; Chen, Xiao-hong
2016-01-01
Linguistic hesitant fuzzy sets (LHFSs), which can be used to represent decision-makers' qualitative preferences as well as reflect their hesitancy and inconsistency, have attracted a great deal of attention due to their flexibility and efficiency. This paper focuses on a multi-criteria decision-making approach that combines LHFSs with the evidential reasoning (ER) method. After reviewing existing studies of LHFSs, a new order relationship and Hamming distance between LHFSs are introduced and some linguistic scale functions are applied. Then, the ER algorithm is used to aggregate the distributed assessment of each alternative. Subsequently, the set of aggregated alternatives on criteria are further aggregated to get the overall value of each alternative. Furthermore, a nonlinear programming model is developed and genetic algorithms are used to obtain the optimal weights of the criteria. Finally, two illustrative examples are provided to show the feasibility and usability of the method, and comparison analysis with the existing method is made.
逻辑系统L*中基于Г-演绎真度的近似推理%Approximate Reasoning Based onΓ-deduction Truth Degree in L* Logic System
Institute of Scientific and Technical Information of China (English)
郝国平; 惠小静; 赵玛瑙
2015-01-01
This paper introduces theΓ-deduction truth degree of formulas in L* logic system at first. Based onΓ-deduction truth degree, this paper definesΓ-deduction similarity degree and pseudo distance, and discusses some basic properties. Then this paper defines three different types of approximate reasoning models in L* logical system, and conducts a detailed analysis on the relationship between three different types of approximate reasoning models ofΓ-deduction truth degree. Finally, three types of approximate reasoning models are equivalent. The research in this paper lays a good foundation for further research on the divergence and compatibility ofΓ-deduction truth degree and approximate reasoning.%在逻辑系统L*中引入了公式Γ-演绎真度的概念，在Γ-演绎真度的基础上，定义了Γ-演绎相似度与伪距离，并讨论了它的一些基本性质。接着在逻辑系统L*中定义了3种不同类型的近似推理模式，对Γ-演绎真度的3种不同类型的近似推理模式之间的关系进行了详细的研究，结果表明这3种不同类型近似推理模式是等价的。通过对这些理论的研究，为进一步研究基于Γ-演绎真度的发散度、相容度和近似推理奠定了良好的基础。
Wu, Kun; Zhang, Feng; Min, Jinzhong; Yu, Qiu-Run; Wang, Xin-Yue; Ma, Leiming
2016-09-01
The adding method, which could calculate the infrared radiative transfer (IRT) in inhomogeneous atmosphere with multiple layers, has been applied to δ -four-stream discrete ordinate method (DOM). This scheme is referred as δ -4DDA. However, there is a lack of application for adding method of δ -four-stream spherical harmonic expansion approximation (SHM) to solve infrared radiative transfer through multiple layers. In this paper, the adding method for δ -four-stream SHM (δ -4SDA) will be obtained and the accuracy of it will be evaluated as well. The result of δ -4SDA in an idealized medium with homogeneous optical property is significantly more accurate than that of the adding method for δ -two-stream DOM (δ -2DDA). The relative errors of δ -2DDA can be over 15% in thin optical depths for downward emissivity, while errors of δ -4SDA are bounded by 2%. However, the result of δ -4SDA is slightly less accurate than that of δ -4DDA. In a radiation model with realistic atmospheric profile considering gaseous transmission, the accuracy for heating rate of δ -4SDA is significantly superior than that of δ -2DDA, especially for the cloudy sky. The accuracy for heating rate of δ -4SDA is slightly less accurate than that of δ -4DDA under water cloud conditions, while it is superior than that of δ -4DDA in ice cloud cases. Beside, the computational efficiency of δ -4SDA is higher than that of δ -4DDA.
Bayesian network modeling method based on case reasoning for emergency decision-making
Directory of Open Access Journals (Sweden)
XU Lei
2013-06-01
Full Text Available Bayesian network has the abilities of probability expression, uncertainty management and multi-information fusion.It can support emergency decision-making, which can improve the efficiency of decision-making.Emergency decision-making is highly time sensitive, which requires shortening the Bayesian Network modeling time as far as possible.Traditional Bayesian network modeling methods are clearly unable to meet that requirement.Thus, a Bayesian network modeling method based on case reasoning for emergency decision-making is proposed.The method can obtain optional cases through case matching by the functions of similarity degree and deviation degree.Then,new Bayesian network can be built through case adjustment by case merging and pruning.An example is presented to illustrate and test the proposed method.The result shows that the method does not have a huge search space or need sample data.The only requirement is the collection of expert knowledge and historical case models.Compared with traditional methods, the proposed method can reuse historical case models, which can reduce the modeling time and improve the efficiency.
Improved locality-sensitive hashing method for the approximate nearest neighbor problem
Lu, Ying-Hua; Ma, Ting-Huai; Zhong, Shui-Ming; Cao, Jie; Wang, Xin; Abdullah, Al-Dhelaan
2014-08-01
In recent years, the nearest neighbor search (NNS) problem has been widely used in various interesting applications. Locality-sensitive hashing (LSH), a popular algorithm for the approximate nearest neighbor problem, is proved to be an efficient method to solve the NNS problem in the high-dimensional and large-scale databases. Based on the scheme of p-stable LSH, this paper introduces a novel improvement algorithm called randomness-based locality-sensitive hashing (RLSH) based on p-stable LSH. Our proposed algorithm modifies the query strategy that it randomly selects a certain hash table to project the query point instead of mapping the query point into all hash tables in the period of the nearest neighbor query and reconstructs the candidate points for finding the nearest neighbors. This improvement strategy ensures that RLSH spends less time searching for the nearest neighbors than the p-stable LSH algorithm to keep a high recall. Besides, this strategy is proved to promote the diversity of the candidate points even with fewer hash tables. Experiments are executed on the synthetic dataset and open dataset. The results show that our method can cost less time consumption and less space requirements than the p-stable LSH while balancing the same recall.
Improved locality-sensitive hashing method for the approximate nearest neighbor problem
International Nuclear Information System (INIS)
In recent years, the nearest neighbor search (NNS) problem has been widely used in various interesting applications. Locality-sensitive hashing (LSH), a popular algorithm for the approximate nearest neighbor problem, is proved to be an efficient method to solve the NNS problem in the high-dimensional and large-scale databases. Based on the scheme of p-stable LSH, this paper introduces a novel improvement algorithm called randomness-based locality-sensitive hashing (RLSH) based on p-stable LSH. Our proposed algorithm modifies the query strategy that it randomly selects a certain hash table to project the query point instead of mapping the query point into all hash tables in the period of the nearest neighbor query and reconstructs the candidate points for finding the nearest neighbors. This improvement strategy ensures that RLSH spends less time searching for the nearest neighbors than the p-stable LSH algorithm to keep a high recall. Besides, this strategy is proved to promote the diversity of the candidate points even with fewer hash tables. Experiments are executed on the synthetic dataset and open dataset. The results show that our method can cost less time consumption and less space requirements than the p-stable LSH while balancing the same recall. (general)
Albrecht, Andreas A; Day, Luke; Abdelhadi Ep Souki, Ouala; Steinhöfel, Kathleen
2016-02-01
The analysis of energy landscapes plays an important role in mathematical modelling, simulation and optimisation. Among the main features of interest are the number and distribution of local minima within the energy landscape. Granier and Kallel proposed in 2002 a new sampling procedure for estimating the number of local minima. In the present paper, we focus on improved heuristic implementations of the general framework devised by Granier and Kallel with regard to run-time behaviour and accuracy of predictions. The new heuristic method is demonstrated for the case of partial energy landscapes induced by RNA secondary structures. While the computation of minimum free energy RNA secondary structures has been studied for a long time, the analysis of folding landscapes has gained momentum over the past years in the context of co-transcriptional folding and deeper insights into cell processes. The new approach has been applied to ten RNA instances of length between 99 nt and 504 nt and their respective partial energy landscapes defined by secondary structures within an energy offset ΔE above the minimum free energy conformation. The number of local minima within the partial energy landscapes ranges from 1440 to 3441. Our heuristic method produces for the best approximations on average a deviation below 3.0% from the true number of local minima.
International Nuclear Information System (INIS)
This thesis focuses on mathematical analysis, numerical resolution and modelling of the transport equations. First of all, we deal with numerical approximation of the solution of the transport equations by using a mixed-hybrid scheme. We derive and study a mixed formulation of the transport equation, then we analyse the related variational problem and present the discretization and the main properties of the scheme. We particularly pay attention to the behavior of the scheme and we show its efficiency in the diffusion limit (when the mean free path is small in comparison with the characteristic length of the physical domain). We present academical benchmarks in order to compare our scheme with other methods in many physical configurations and validate our method on analytical test cases. Unstructured and very distorted meshes are used to validate our scheme. The second part of this thesis deals with two transport problems. The first one is devoted to the study of diffusion due to boundary conditions in a transport problem between two plane plates. The second one consists in modelling and simulating radiative transfer phenomenon in case of the industrial context of inertial confinement fusion. (author)
Rößler, Andreas
2013-01-01
A general class of stochastic Runge-Kutta methods for the weak approximation of It\\^o and Stratonovich stochastic differential equations with a multi-dimensional Wiener process is introduced. Colored rooted trees are used to derive an expansion of the solution process and of the approximation process calculated with the stochastic Runge-Kutta method. A theorem on general order conditions for the coefficients and the random variables of the stochastic Runge-Kutta method is proved by rooted tre...
2006-01-01
This interactive tutorial presents the following concepts of Approximation Techniques: Methods of Weighted Residual (MWR), Weak Formulatioin, Piecewise Continuous Function, Galerkin Finite Element FormulationExplanations especially for mathematical statements are provided using mouseover the highlight equations. ME4613 Finite Element Methods
Scalable learning method for feedforward neural networks using minimal-enclosing-ball approximation.
Wang, Jun; Deng, Zhaohong; Luo, Xiaoqing; Jiang, Yizhang; Wang, Shitong
2016-06-01
Training feedforward neural networks (FNNs) is one of the most critical issues in FNNs studies. However, most FNNs training methods cannot be directly applied for very large datasets because they have high computational and space complexity. In order to tackle this problem, the CCMEB (Center-Constrained Minimum Enclosing Ball) problem in hidden feature space of FNN is discussed and a novel learning algorithm called HFSR-GCVM (hidden-feature-space regression using generalized core vector machine) is developed accordingly. In HFSR-GCVM, a novel learning criterion using L2-norm penalty-based ε-insensitive function is formulated and the parameters in the hidden nodes are generated randomly independent of the training sets. Moreover, the learning of parameters in its output layer is proved equivalent to a special CCMEB problem in FNN hidden feature space. As most CCMEB approximation based machine learning algorithms, the proposed HFSR-GCVM training algorithm has the following merits: The maximal training time of the HFSR-GCVM training is linear with the size of training datasets and the maximal space consumption is independent of the size of training datasets. The experiments on regression tasks confirm the above conclusions. PMID:27049545
Garvie, Marcus R; Burkardt, John; Morgan, Jeff
2015-03-01
We describe simple finite element schemes for approximating spatially extended predator-prey dynamics with the Holling type II functional response and logistic growth of the prey. The finite element schemes generalize 'Scheme 1' in the paper by Garvie (Bull Math Biol 69(3):931-956, 2007). We present user-friendly, open-source MATLAB code for implementing the finite element methods on arbitrary-shaped two-dimensional domains with Dirichlet, Neumann, Robin, mixed Robin-Neumann, mixed Dirichlet-Neumann, and Periodic boundary conditions. Users can download, edit, and run the codes from http://www.uoguelph.ca/~mgarvie/ . In addition to discussing the well posedness of the model equations, the results of numerical experiments are presented and demonstrate the crucial role that habitat shape, initial data, and the boundary conditions play in determining the spatiotemporal dynamics of predator-prey interactions. As most previous works on this problem have focussed on square domains with standard boundary conditions, our paper makes a significant contribution to the area.
Garvie, Marcus R; Burkardt, John; Morgan, Jeff
2015-03-01
We describe simple finite element schemes for approximating spatially extended predator-prey dynamics with the Holling type II functional response and logistic growth of the prey. The finite element schemes generalize 'Scheme 1' in the paper by Garvie (Bull Math Biol 69(3):931-956, 2007). We present user-friendly, open-source MATLAB code for implementing the finite element methods on arbitrary-shaped two-dimensional domains with Dirichlet, Neumann, Robin, mixed Robin-Neumann, mixed Dirichlet-Neumann, and Periodic boundary conditions. Users can download, edit, and run the codes from http://www.uoguelph.ca/~mgarvie/ . In addition to discussing the well posedness of the model equations, the results of numerical experiments are presented and demonstrate the crucial role that habitat shape, initial data, and the boundary conditions play in determining the spatiotemporal dynamics of predator-prey interactions. As most previous works on this problem have focussed on square domains with standard boundary conditions, our paper makes a significant contribution to the area. PMID:25616741
Wang, S.; Zhang, X. N.; Gao, D. D.; Liu, H. X.; Ye, J.; Li, L. R.
2016-08-01
As the solar photovoltaic (PV) power is applied extensively, more attentions are paid to the maintenance and fault diagnosis of PV power plants. Based on analysis of the structure of PV power station, the global partitioned gradually approximation method is proposed as a fault diagnosis algorithm to determine and locate the fault of PV panels. The PV array is divided into 16x16 blocks and numbered. On the basis of modularly processing of the PV array, the current values of each block are analyzed. The mean current value of each block is used for calculating the fault weigh factor. The fault threshold is defined to determine the fault, and the shade is considered to reduce the probability of misjudgments. A fault diagnosis system is designed and implemented with LabVIEW. And it has some functions including the data realtime display, online check, statistics, real-time prediction and fault diagnosis. Through the data from PV plants, the algorithm is verified. The results show that the fault diagnosis results are accurate, and the system works well. The validity and the possibility of the system are verified by the results as well. The developed system will be benefit for the maintenance and management of large scale PV array.
Miller, Eric L.; Willsky, Alan S.
1996-01-01
In this paper, we present an approach to the nonlinear inverse scattering problem using the extended Born approximation (EBA) on the basis of methods from the fields of multiscale and statistical signal processing. By posing the problem directly in the wavelet transform domain, regularization is provided through the use of a multiscale prior statistical model. Using the maximum a posteriori (MAP) framework, we introduce the relative Cramér-Rao bound (RCRB) as a tool for analyzing the level of detail in a reconstruction supported by a data set as a function of the physics, the source-receiver geometry, and the nature of our prior information. The MAP estimate is determined using a novel implementation of the Levenberg-Marquardt algorithm in which the RCRB is used to achieve a substantial reduction in the effective dimensionality of the inversion problem with minimal degradation in performance. Additional reduction in complexity is achieved by taking advantage of the sparse structure of the matrices defining the EBA in scale space. An inverse electrical conductivity problem arising in geophysical prospecting applications provides the vehicle for demonstrating the analysis and algorithmic techniques developed in this paper.
Institute of Scientific and Technical Information of China (English)
BAI Yu-Lin; CHENG Xiao-Hong; CHEN Xiang-Rong; YANG Xiang-Dong; ZHU Jun
2004-01-01
@@ The intermolecular interactions potentials for two configurations of CH4-Ne complex are calculated with local density approximation methods in the frame of density functional theory. It is found that the calculated potentials have two minima when the distance between the carbon atom of CH4 and the Ne atom takes R = 5.80 a.u.and 6.20a. u. for both the two configurations. For the edge configuration, the corresponding depth of the potential is 0.0669536 eV and 0.0671416 eV. For the face configuration, the corresponding depth of the potential is 0.0737956 eV and 0.0645506 eV. The global minimum occurs at R = 5.80 a.u. for the face configuration with a depth of the potential 0.0737956 eV. The depths of our calculation are in better agreement with the experimental data than the quantum chemical calculation approach, while the position of minimum potential for our calculation is underestimated.
International Nuclear Information System (INIS)
In this paper we present the results of a short phenomenological investigation on indirect heat transfer. The aim of this investigation is to gain a better understanding towards the service life of a solid structure subject to thermal stresses (e.g., a pipeline). A numerical scheme, based on finite approximations, is used to estimate temperature profiles at an inaccessible wall. Such a situation occurs in a nuclear power plant, for example, when monitoring pipelines subject to thermal stresses. Due to the operating conditions (e.g., high pressure and/or high temperatures) it is not always feasible to measure the temperature at each location of the pipeline. Therefore, the temperature is measured at a certain location (for instance, at an outer surface) and the temperature at the inner surface, must be estimated. The word estimate is used to indicate that an exact solution at the given conditions is not known, or is not suitable for use in practice. Thus, the estimation of the temperature can be seen as an indirect method for the prediction of temperature profiles. Accurate estimation of the temperature profiles relies on the quality of the measurements. This serves as a basis for monitoring and predicting the expected service life in systems such as pipelines. (author)
Energy Technology Data Exchange (ETDEWEB)
Belendez, A. [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es; Hernandez, A.; Belendez, T.; Neipp, C.; Marquez, A. [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)
2008-03-17
He's homotopy perturbation method is used to calculate higher-order approximate periodic solutions of a nonlinear oscillator with discontinuity for which the elastic force term is proportional to sgn(x). We find He's homotopy perturbation method works very well for the whole range of initial amplitudes, and the excellent agreement of the approximate frequencies and periodic solutions with the exact ones has been demonstrated and discussed. Only one iteration leads to high accuracy of the solutions with a maximal relative error for the approximate period of less than 1.56% for all values of oscillation amplitude, while this relative error is 0.30% for the second iteration and as low as 0.057% when the third-order approximation is considered. Comparison of the result obtained using this method with those obtained by different harmonic balance methods reveals that He's homotopy perturbation method is very effective and convenient.
International Nuclear Information System (INIS)
In this Letter, an enhanced Adomian decomposition method which introduces the h-curve of the homotopy analysis method into the standard Adomian decomposition method is proposed. Some examples prove that this method can derive successfully approximate rational Jacobi elliptic function solutions of the fractional differential equations.
Gadella, M; Negro, J
2016-01-01
We compare three different methods to obtain solutions of Sturm-Liouville problems: a successive approximation method and two other iterative methods. We look for solutions with periodic or anti periodic boundary conditions. With some numerical test over the Mathieu equation, we compare the efficiency of these three methods. As an application, we make a numerical analysis on a model for carbon nanotubes.
A penalty method for approximations of the stationary power-law Stokes problem
Directory of Open Access Journals (Sweden)
Lew Lefton
2001-01-01
Full Text Available We study approximations of the steady state Stokes problem governed by the power-law model for viscous incompressible non-Newtonian flow using the penalty formulation. We establish convergence and find error estimates.
Institute of Scientific and Technical Information of China (English)
崔美华
2012-01-01
利用赋值集的随机化方法,在n值Lukasiewicz命题逻辑系统中引入公式的随机真度,证明了随机真度的MP规则、HS规则及交推理规则；同时引入公式间的随机相似度和随机伪距离,建立了随机逻辑度量空间,推导出随机相似度的若干性质,证明了随机逻辑度量空间中逻辑运算的连续性；并在随机逻辑度量空间中提出了三种不同类型的近似推理模式,证明了三种近似推理模式的等价性.%Using the randomization method of valuation set, the concept of randomized truth degree of formulas is introduced into n-valued Lukasiewicz propositional logic system. The MP rule, HS rule and meet inference rules of randomized truth degree are proved. At the meantime, the concept of randomized similarity and randomized pseudo-distances between formulas are introduced and the randomized logic metric space is bmilt. Several properties of randomized similarity are deduced to prove the continuity of logical operations in this space. Three different types of approximate reasoning patterns are introduced in randomized logic metric space. And they are proved to be equivalent.
A novel window based method for approximating the Hausdorff in 3D range imagery.
Energy Technology Data Exchange (ETDEWEB)
Koch, Mark William
2004-10-01
Matching a set of 3D points to another set of 3D points is an important part of any 3D object recognition system. The Hausdorff distance is known for it robustness in the face of obscuration, clutter, and noise. We show how to approximate the 3D Hausdorff fraction with linear time complexity and quadratic space complexity. We empirically demonstrate that the approximation is very good when compared to actual Hausdorff distances.
Research on conflict resolution of collaborative design with fuzzy case-based reasoning method
Institute of Scientific and Technical Information of China (English)
HOU Jun-ming; SU Chong; LIANG Shuang; WANG Wan-shan
2009-01-01
Collaborative design is a new style for modern mechanical design to meet the requirement of increasing competition. Designers of different places complete the same work, but the conflict appears in the process of design which may interface the design. Case-based reasoning (CBR) method is applied to the problem of conflict resolution, which is in the artificial intelligence field. However, due to the uncertainties in knowledge representation, attribute description, and similarity measures of CBR, it is very difficult to find the similar cases from case database. A fuzzy CBR method was proposed to solve the problem of conflict resolution in collaborative design. The process of fuzzy CBR was introduced. Based on the feature attributes and their relative weights determined by a fuzzy technique, a fuzzy CBR retrieving mechanism was developed to retrieve conflict resolution cases that tend to enhance the functions of the database. By indexing, calculating the weight and defuzzicating of the cases, the case similarity can be obtained. Then the case consistency was measured to keep the right result. Finally, the fuzzy CBR method for conflict resolution was demonstrated by means of a case study. The prototype system based on web is developed to illustrate the methodology.
Stochastic approximation methods for fusion-rule estimation in multiple sensor systems
Energy Technology Data Exchange (ETDEWEB)
Rao, N.S.V.
1994-06-01
A system of N sensors S{sub 1}, S{sub 2},{hor_ellipsis},S{sub N} is considered; corresponding to an object with parameter x {element_of} {Re}{sup d}, sensor S{sub i} yields output y{sup (i)}{element_of}{Re}{sup d} according to an unknown probability distribution p{sub i}(y{sup (i)}{vert_bar}x). A training l-sample (x{sub 1}, y{sub 1}), (x{sub 2}, y{sub 2}),{hor_ellipsis},(x{sub l}, y{sub l}) is given where y{sub i} = (y{sub i}({sup 1}), y{sub i}({sup 2}),{hor_ellipsis},y{sub i}({sup N}) and y{sub i}({sup j}) is the output of S{sub j} in response to input X{sub i}. The problem is to estimate a fusion rule f : {Re}{sup Nd} {yields} {Re}{sup d}, based on the sample, such that the expected square error I(f) = {integral}[x {minus} f(y{sup 1}, y{sup 2},{hor_ellipsis},y{sup N})]{sup 2} p(y{sup 1}, y{sup 2},{hor_ellipsis},y{sup N}){vert_bar}x)p(x)dy{sup 1}dy{sup 2} {hor_ellipsis} dy{sup N}dx is to be minimized over a family of fusion rules {lambda} based on the given l-sample. Let f{sub *} {element_of} {lambda} minimize I(f); f{sub *} cannot be computed since the underlying probability distributions are unknown. Three stochastic approximation methods are presented to compute {cflx f}, such that under suitable conditions, for sufficiently large sample, P[I{cflx f} {minus} I(f{sub *}) > {epsilon}] < {delta} for arbitrarily specified {epsilon} > 0 and {delta}, 0 < {delta} < 1. The three methods are based on Robbins-Monro style algorithms, empirical risk minimization, and regression estimation algorithms.
Michel, Volker
2013-01-01
Lectures on Constructive Approximation: Fourier, Spline, and Wavelet Methods on the Real Line, the Sphere, and the Ball focuses on spherical problems as they occur in the geosciences and medical imaging. It comprises the author’s lectures on classical approximation methods based on orthogonal polynomials and selected modern tools such as splines and wavelets. Methods for approximating functions on the real line are treated first, as they provide the foundations for the methods on the sphere and the ball and are useful for the analysis of time-dependent (spherical) problems. The author then examines the transfer of these spherical methods to problems on the ball, such as the modeling of the Earth’s or the brain’s interior. Specific topics covered include: * the advantages and disadvantages of Fourier, spline, and wavelet methods * theory and numerics of orthogonal polynomials on intervals, spheres, and balls * cubic splines and splines based on reproducing kernels * multiresolution analysis using wavelet...
Directory of Open Access Journals (Sweden)
Kováč Michal
2015-03-01
Full Text Available Thin-walled centrically compressed members with non-symmetrical or mono-symmetrical cross-sections can buckle in a torsional-flexural buckling mode. Vlasov developed a system of governing differential equations of the stability of such member cases. Solving these coupled equations in an analytic way is only possible in simple cases. Therefore, Goľdenvejzer introduced an approximate method for the solution of this system to calculate the critical axial force of torsional-flexural buckling. Moreover, this can also be used in cases of members with various boundary conditions in bending and torsion. This approximate method for the calculation of critical force has been adopted into norms. Nowadays, we can also solve governing differential equations by numerical methods, such as the finite element method (FEM. Therefore, in this paper, the results of the approximate method and the FEM were compared to each other, while considering the FEM as a reference method. This comparison shows any discrepancies of the approximate method. Attention was also paid to when and why discrepancies occur. The approximate method can be used in practice by considering some simplifications, which ensure safe results.
Optimal approximation method to characterize the resource trade-off functions for media servers
Chang, Ray-I.
1999-08-01
We have proposed an algorithm to smooth the transmission of the pre-recorded VBR media stream. It takes O(n) time complexity, where n is large, this algorithm is not suitable for online resource management and admission control in media servers. To resolve this drawback, we have explored the optimal tradeoff among resources by an O(nlogn) algorithm. Based on the pre-computed resource tradeoff function, the resource management and admission control procedure is as simple as table hashing. However, this approach requires O(n) space to store and maintain the resource tradeoff function. In this paper, while giving some extra resources, a linear-time algorithm is proposed to approximate the resource tradeoff function by piecewise line segments. We can prove that the number of line segments in the obtained approximation function is minimized for the given extra resources. The proposed algorithm has been applied to approximate the bandwidth-buffer-tradeoff function of the real-world Star War movie. While an extra 0.1 Mbps bandwidth is given, the storage space required for the approximation function is over 2000 times smaller than that required for the original function. While an extra 10 KB buffer is given, the storage space for the approximation function is over 2200 over times smaller than that required for the original function. The proposed algorithm is really useful for resource management and admission control in real-world media servers.
Institute of Scientific and Technical Information of China (English)
白振东; 刘虎; 柴雪; 武哲
2008-01-01
为提高飞机多学科优化效率,对气动近似计算模型进行了改进.在比值修正模型所构造的气动近似模型的基础上,引入了基于实例的推理技术对其加以改进.通过采用与飞机气动特性相关的参数作为实例属性,建立了飞机方案实例,并改进了实例检索公式,最后通过复用与当前方案最相似实例的修正因子改进了优化中的气动近似模型.以常规布局民用飞机概念设计为例,采用改进的气动近似模型进行了多学科优化研究.结果表明,对于具有大量设计变量的飞机方案优化问题,采用改进的气动近似模型能够有效提高计算精度与优化效率.%To increase the efficiency of the muhidisciplinary optimization of aircraft,an aerodynamic approximation model is improved.Based on the study of aerodynamic approximation model constructed by the scaling correction model,case-based reasoning technique is introduced to improve the approximation model for optimization.The aircraft case model is constructed by utilizing the plane parameters related to aerodynamic characteristics as attributes of cases,and the formula of case retrieving is improved.Finally,the aerodynamic approximation model for optimization is improved by reusing the correction factors of the most similar aircraft to the current one.The muhidisciplinary optimization of a civil aircraft concept is carried out with the improved aerodynamic approximation model.The results demonstrate that the precision and the efficiency of the optimization can be improved by utilizing the improved aerodynamic approximation model with case-based reasoning technique.
Identifying reasons for delays in acute hospitals using the Day-of-Care Survey method.
Reid, Erica; King, Andrew; Mathieson, Alex; Woodcock, Thomas; Watkin, Simon W
2015-04-01
This paper describes a new tool called 'Day-of-Care Survey', developed to assess inpatient delays in acute hospitals. Using literature review, iterative testing and feedback from professional groups, a national multidisciplinary team developed the survey criteria and methodology. Review teams working in pairs visited wards and used case records and bedside charts to assess the patient's status against severity of illness and service intensity criteria. Patients who did not meet the survey criteria for acute care were identified and delays were categorised. From March 2012 to December 2013, nine acute hospitals across Scotland, Australia and England were surveyed. A total of 3,846 adult general inpatient beds (excluding intensive care and maternity) were reviewed. There were 145 empty beds at the time of surveys across the nine sites, with 270 definite discharges planned on the day of the survey. The total number of patients not meeting criteria for acute care was 798/3,431 (23%, range 18-28%). Six factors accounted for 61% (490/798) of the reasons why patients not meeting acute care criteria remained in hospital. This survey gives important insights into the challenges of managing inpatient flow using system level information as a method to target interventions designed to address delay.
Intelligent design of investment casting mold based on a hybrid reasoning method
Institute of Scientific and Technical Information of China (English)
Jiang Ruisong; Zhang Dinghua; Wang Wenhu; Bu Kun
2009-01-01
A hybrid reasoning model was proposed in which CBR (case-based reasoning) was applied to the conceptual design and RBR (rule-based reasoning) was applied to the detailed design after research of the design process and domain knowledge of the acre-engine turbine blade investment casting mold design field. In the conceptual design stage, the representation and retrieval technologies were researched which improve the retrieval efficiency. Meanwhile, RBR was used to modify the retrieval result. The experimentation shows that the approach in this study can be used to obtain a more satisfactory design result.
A Diffusion Approximation and Numerical Methods for Adaptive Neuron Models with Stochastic Inputs.
Rosenbaum, Robert
2016-01-01
Characterizing the spiking statistics of neurons receiving noisy synaptic input is a central problem in computational neuroscience. Monte Carlo approaches to this problem are computationally expensive and often fail to provide mechanistic insight. Thus, the field has seen the development of mathematical and numerical approaches, often relying on a Fokker-Planck formalism. These approaches force a compromise between biological realism, accuracy and computational efficiency. In this article we develop an extension of existing diffusion approximations to more accurately approximate the response of neurons with adaptation currents and noisy synaptic currents. The implementation refines existing numerical schemes for solving the associated Fokker-Planck equations to improve computationally efficiency and accuracy. Computer code implementing the developed algorithms is made available to the public. PMID:27148036
International Nuclear Information System (INIS)
A method for the approximate calculation of the composition of the detonation products of gas mixtures is reported in the paper. The method is based on the assumption of partial equilibrium in the subsystem of biomolecular reactions. The description of the equilibrium composition in the subsystem of biomolecular reactions is reduced to the solution of the system of linear equations
Institute of Scientific and Technical Information of China (English)
HU Xian-lei; ZHANG Qi-sheng; ZHAO Zhong; TIAN Yong; LIU Xiang-hua; WANG Guo-dong
2006-01-01
The influence of positive bending system on plate crown control was researched. The approximation full-load distribution method for pass scheduling was put forward. This method can not only make full use of the mill capacity with decreased pass number, but also give quality product of excellent flatness.
A new weak approximation scheme of stochastic differential equations and the Runge-Kutta method
Ninomiya, Mariko; Ninomiya, Syoiti
2007-01-01
In this paper, authors successfully construct a new algorithm for the new higher order scheme of weak approximation of SDEs. The algorithm presented here is based on [1][2]. Although this algorithm shares some features with the algorithm presented by [3], algorithms themselves are completely different and the diversity is not trivial. They apply this new algorithm to the problem of pricing Asian options under the Heston stochastic volatility model and obtain encouraging results. [1] Shigeo Ku...
Banks, H. T.; Smith, Ralph C.; Wang, Yun
1994-01-01
Based on a distributed parameter model for vibrations, an approximate finite dimensional dynamic compensator is designed to suppress vibrations (multiple modes with a broad band of frequencies) of a circular plate with Kelvin-Voigt damping and clamped boundary conditions. The control is realized via piezoceramic patches bonded to the plate and is calculated from information available from several pointwise observed state variables. Examples from computational studies as well as use in laboratory experiments are presented to demonstrate the effectiveness of this design.
Energy Technology Data Exchange (ETDEWEB)
Modarres, M., E-mail: mmodares@ut.ac.ir [Physics Department, University of Tehran, North-Kargar Ave., 1439955961 Tehran (Iran, Islamic Republic of); Tafrihi, A.; Hatami, A. [Physics Department, University of Tehran, North-Kargar Ave., 1439955961 Tehran (Iran, Islamic Republic of)
2012-04-01
The neutron matter equation of states of the so-called Bethe homework problem (NMESB) is obtained using the (extended) lowest order constrained variational ((E) LOCV), the lowest order factorized Iwamoto-Yamada (LOF) and the Fermi (hypernetted) chain (FC (FHNC)) formalisms. The FC and the FHNC approximations are performed, using the LOCV or the ELOCV correlation function. It is shown that, if the normalization constraint is satisfied, then the NMESB results by using the LOCV, the ELOCV, the FC and the FHNC formalisms, will become close together and agree well with the corresponding FHNC calculations performed by Zabolitzky (Z) with the parameterized Krotscheck and Takahashi (KT) correlation function. It is also demonstrated that the LOF and the FC calculations, evaluated by employing a parameterized correlation function, are far from the above results, particularly at high densities. Finally, in order to test the convergence of LOF approximation, the two- and the three-body normalization factors are calculated and it is shown that in the LOF approximation, the truncation of cluster expansion after the first few leading terms is not reliable (which is well known as the Emery difficulty).
International Nuclear Information System (INIS)
The neutron matter equation of states of the so-called Bethe homework problem (NMESB) is obtained using the (extended) lowest order constrained variational ((E) LOCV), the lowest order factorized Iwamoto–Yamada (LOF) and the Fermi (hypernetted) chain (FC (FHNC)) formalisms. The FC and the FHNC approximations are performed, using the LOCV or the ELOCV correlation function. It is shown that, if the normalization constraint is satisfied, then the NMESB results by using the LOCV, the ELOCV, the FC and the FHNC formalisms, will become close together and agree well with the corresponding FHNC calculations performed by Zabolitzky (Z) with the parameterized Krotscheck and Takahashi (KT) correlation function. It is also demonstrated that the LOF and the FC calculations, evaluated by employing a parameterized correlation function, are far from the above results, particularly at high densities. Finally, in order to test the convergence of LOF approximation, the two- and the three-body normalization factors are calculated and it is shown that in the LOF approximation, the truncation of cluster expansion after the first few leading terms is not reliable (which is well known as the Emery difficulty).
Understanding Set Cover: Sub-exponential Time Approximations and Lift-and-Project Methods
Chlamtac, Eden; Georgiou, Konstantinos
2012-01-01
We study sub-exponential time approximation algorithms for the Set-Cover problem. Our main algorithmic result is a combinatorial ln(n/d)+O(1) approximation in poly(n,m)*m^O(d) time, where n is the number of items to be covered and m is the number of sets. Setting d = n^eps for any constant 0 < eps < 1 results in a (1-eps)*ln n approximation running in sub-exponential time. By recent work of Moshkovitz, assuming the Projection Games Conjecture, the running time of our algorithm is optimal up to a constant factor in the exponent of n, unless SAT has sub-exponential time algorithms. At a high level, our algorithm is similar to a well-known PTAS for Knapsack. Recently, Karlin, Mathieu, and Nguyen examined this PTAS and its connection to hierarchies of linear programming (LP) and semidefinite programing (SDP) relaxations for Knapsack. Inspired by their work, we also consider the integrality gap of Set-Cover relaxations arising from such hierarchies. We show that, using the trick of "lifting the objective fun...
Directory of Open Access Journals (Sweden)
Yousri Slaoui
2014-01-01
Full Text Available We propose an automatic selection of the bandwidth of the recursive kernel estimators of a probability density function defined by the stochastic approximation algorithm introduced by Mokkadem et al. (2009a. We showed that, using the selected bandwidth and the stepsize which minimize the MISE (mean integrated squared error of the class of the recursive estimators defined in Mokkadem et al. (2009a, the recursive estimator will be better than the nonrecursive one for small sample setting in terms of estimation error and computational costs. We corroborated these theoretical results through simulation study.
Methods and tools for simplified dynamic simulations in real time based on expression approximation
Directory of Open Access Journals (Sweden)
Štefan M.
2007-10-01
Full Text Available The core of this paper is the methodology of the dynamicalmodels’ simplification for the real time simulation. The simplified simulation models are based on neuro-fuzzymodelling approach, which was originally designed for predictive control-orientedmodelling of nonlinear dynamical systems. The two ways of the neuro-fuzzymodelling utilization are presented. First, the training of the predictive dynamical neuro-fuzzymodel and, second, the training of the statical approximation of the right-hand side of the system’s state space description. We demonstrate the results on the examples of nonlinear spring damper system and double pendulum.
Non-Equilibrium Liouville and Wigner Equations: Moment Methods and Long-Time Approximations
Directory of Open Access Journals (Sweden)
Ramon F. Álvarez-Estrada
2014-03-01
Full Text Available We treat the non-equilibrium evolution of an open one-particle statistical system, subject to a potential and to an external “heat bath” (hb with negligible dissipation. For the classical equilibrium Boltzmann distribution, Wc,eq, a non-equilibrium three-term hierarchy for moments fulfills Hermiticity, which allows one to justify an approximate long-time thermalization. That gives partial dynamical support to Boltzmann’s Wc,eq, out of the set of classical stationary distributions, Wc;st, also investigated here, for which neither Hermiticity nor that thermalization hold, in general. For closed classical many-particle systems without hb (by using Wc,eq, the long-time approximate thermalization for three-term hierarchies is justified and yields an approximate Lyapunov function and an arrow of time. The largest part of the work treats an open quantum one-particle system through the non-equilibrium Wigner function, W. Weq for a repulsive finite square well is reported. W’s (< 0 in various cases are assumed to be quasi-definite functionals regarding their dependences on momentum (q. That yields orthogonal polynomials, HQ,n(q, for Weq (and for stationary Wst, non-equilibrium moments, Wn, of W and hierarchies. For the first excited state of the harmonic oscillator, its stationary Wst is a quasi-definite functional, and the orthogonal polynomials and three-term hierarchy are studied. In general, the non-equilibrium quantum hierarchies (associated with Weq for the Wn’s are not three-term ones. As an illustration, we outline a non-equilibrium four-term hierarchy and its solution in terms of generalized operator continued fractions. Such structures also allow one to formulate long-time approximations, but make it more difficult to justify thermalization. For large thermal and de Broglie wavelengths, the dominant Weq and a non-equilibrium equation for W are reported: the non-equilibrium hierarchy could plausibly be a three-term one and possibly not
AN APPROXIMATION METHOD TO ESTIMATE THE HAUSDORFF MEASURE OF THE SIERPINSKI GASKET
Institute of Scientific and Technical Information of China (English)
Ruan Huojun; Su Weiyi
2004-01-01
In this paper, we firstly define a decreasing sequence {Pn(S)} by the generation of the Sierpinski gasket where each pn(S) can be obtained in finite steps. Then we prove that the Hausdorff measure Hs(S)of the Sierpinski gasket S can be approximated by {Pn(S)} with Pn(S)/(1 + 1/2n-3)s ≤ Hs(S) ≤ pn(S).An algorithm is presented to get Pn(S) for n ≤ 5. As an application, we obtain the best lower bound of Hs(S) till now: Hs(S) ≥ 0.5631.
International Nuclear Information System (INIS)
Formulas which are needed to calculate transmission coefficients for the adiabatic coupled-channel approximation method are described. In terms of these coefficients, nuclear absorption cross sections may be obtained. First, derivations are given of various cross sections for a system of coupled inelastic channels in terms of the S matrix. The adiabatic approximation method is discussed for a rotational band, and the dynamical nuclear S matrix is obtained from the S matrix for scattering from a static rotor. The formulas are valid for a spheroidal rotor, with or without an extra-core particle, which does not interact with the projectile but does provide angular momentum to the target
Bisetti, Fabrizio
2012-06-01
Recent trends in hydrocarbon fuel research indicate that the number of species and reactions in chemical kinetic mechanisms is rapidly increasing in an effort to provide predictive capabilities for fuels of practical interest. In order to cope with the computational cost associated with the time integration of stiff, large chemical systems, a novel approach is proposed. The approach combines an exponential integrator and Krylov subspace approximations to the exponential function of the Jacobian matrix. The components of the approach are described in detail and applied to the ignition of stoichiometric methane-air and iso-octane-air mixtures, here described by two widely adopted chemical kinetic mechanisms. The approach is found to be robust even at relatively large time steps and the global error displays a nominal third-order convergence. The performance of the approach is improved by utilising an adaptive algorithm for the selection of the Krylov subspace size, which guarantees an approximation to the matrix exponential within user-defined error tolerance. The Krylov projection of the Jacobian matrix onto a low-dimensional space is interpreted as a local model reduction with a well-defined error control strategy. Finally, the performance of the approach is discussed with regard to the optimal selection of the parameters governing the accuracy of its individual components. © 2012 Copyright Taylor and Francis Group, LLC.
Multi-Scaling Sampling: An Adaptive Sampling Method for Discovering Approximate Association Rules
Institute of Scientific and Technical Information of China (English)
Cai-Yan Jia; Xie-Ping Gao
2005-01-01
One of the obstacles of the efficient association rule mining is the explosive expansion of data sets since it is costly or impossible to scan large databases, esp., for multiple times. A popular solution to improve the speed and scalability of the association rule mining is to do the algorithm on a random sample instead of the entire database. But how to effectively define and efficiently estimate the degree of error with respect to the outcome of the algorithm, and how to determine the sample size needed are entangling researches until now. In this paper, an effective and efficient algorithm is given based on the PAC (Probably Approximate Correct) learning theory to measure and estimate sample error. Then, a new adaptive, on-line, fast sampling strategy - multi-scaling sampling - is presented inspired by MRA (Multi-Resolution Analysis) and Shannon sampling theorem, for quickly obtaining acceptably approximate association rules at appropriate sample size. Both theoretical analysis and empirical study have showed that the sampling strategy can achieve a very good speed-accuracy trade-off.
Mohammadpour, Mozhdeh; Jamshidi, Zahra
2016-05-01
The prospect of challenges in reproducing and interpretation of resonance Raman properties of molecules interacting with metal clusters has prompted the present research initiative. Resonance Raman spectra based on the time-dependent gradient approximation are examined in the framework of density functional theory using different methods for representing the exchange-correlation functional. In this work the performance of different XC functionals in the prediction of ground state properties, excitation state energies, and gradients are compared and discussed. Resonance Raman properties based on time-dependent gradient approximation for the strongly low-lying charge transfer states are calculated and compared for different methods. We draw the following conclusions: (1) for calculating the binding energy and ground state geometry, dispersion-corrected functionals give the best performance in comparison to ab initio calculations, (2) GGA and meta GGA functionals give good accuracy in calculating vibrational frequencies, (3) excited state energies determined by hybrid and range-separated hybrid functionals are in good agreement with EOM-CCSD calculations, and (4) in calculating resonance Raman properties GGA functionals give good and reasonable performance in comparison to the experiment; however, calculating the excited state gradient by using the hybrid functional on the hessian of GGA improves the results of the hybrid functional significantly. Finally, we conclude that the agreement of charge-transfer surface enhanced resonance Raman spectra with experiment is improved significantly by using the excited state gradient approximation.
Gökdoğan, Ahmet; Merdan, Mehmet; Yildirim, Ahmet
2012-01-01
The goal of this study is presented a reliable algorithm based on the standard differential transformation method (DTM), which is called the multi-stage differential transformation method (MsDTM) for solving Hantavirus infection model. The results obtanied by using MsDTM are compared to those obtained by using the Runge-Kutta method (R-K-method). The proposed technique is a hopeful tool to solving for a long time intervals in this kind of systems.
Energy Technology Data Exchange (ETDEWEB)
Kim, S. [Purdue Univ., West Lafayette, IN (United States)
1994-12-31
Parallel iterative procedures based on domain decomposition techniques are defined and analyzed for the numerical solution of wave propagation by finite element and finite difference methods. For finite element methods, in a Lagrangian framework, an efficient way for choosing the algorithm parameter as well as the algorithm convergence are indicated. Some heuristic arguments for finding the algorithm parameter for finite difference schemes are addressed. Numerical results are presented to indicate the effectiveness of the methods.
Institute of Scientific and Technical Information of China (English)
崔美华
2013-01-01
In the classical propositional logic system, the D-conditional divergence of theory and the D-conditional pseudo-distance from formula to theory are introduced in D-r logic metric space. Their several properties are deduced. Furthermore, based on them, some related questions on approximate reasoning in D-r logic metric space are studied.%在经典命题逻辑系统中,给出了D-г逻辑度量空间中理论的D-条件发散度和公式到理论的D-条件距离的真度表达式,推出了它们的若干性质；并利用这些性质研究了D-г逻辑度量空间中近似推理的相关问题.
Energy Technology Data Exchange (ETDEWEB)
Freeze, G.A.; Larson, K.W. [INTERA, Inc., Albuquerque, NM (United States); Davies, P.B. [Sandia National Labs., Albuquerque, NM (United States)
1995-10-01
Eight alternative methods for approximating salt creep and disposal room closure in a multiphase flow model of the Waste Isolation Pilot Plant (WIPP) were implemented and evaluated: Three fixed-room geometries three porosity functions and two fluid-phase-salt methods. The pressure-time-porosity line interpolation method is the method used in current WIPP Performance Assessment calculations. The room closure approximation methods were calibrated against a series of room closure simulations performed using a creep closure code, SANCHO. The fixed-room geometries did not incorporate a direct coupling between room void volume and room pressure. The two porosity function methods that utilized moles of gas as an independent parameter for closure coupling. The capillary backstress method was unable to accurately simulate conditions of re-closure of the room. Two methods were found to be accurate enough to approximate the effects of room closure; the boundary backstress method and pressure-time-porosity line interpolation. The boundary backstress method is a more reliable indicator of system behavior due to a theoretical basis for modeling salt deformation as a viscous process. It is a complex method and a detailed calibration process is required. The pressure lines method is thought to be less reliable because the results were skewed towards SANCHO results in simulations where the sequence of gas generation was significantly different from the SANCHO gas-generation rate histories used for closure calibration. This limitation in the pressure lines method is most pronounced at higher gas-generation rates and is relatively insignificant at lower gas-generation rates. Due to its relative simplicity, the pressure lines method is easier to implement in multiphase flow codes and simulations have a shorter execution time.
International Nuclear Information System (INIS)
Eight alternative methods for approximating salt creep and disposal room closure in a multiphase flow model of the Waste Isolation Pilot Plant (WIPP) were implemented and evaluated: Three fixed-room geometries three porosity functions and two fluid-phase-salt methods. The pressure-time-porosity line interpolation method is the method used in current WIPP Performance Assessment calculations. The room closure approximation methods were calibrated against a series of room closure simulations performed using a creep closure code, SANCHO. The fixed-room geometries did not incorporate a direct coupling between room void volume and room pressure. The two porosity function methods that utilized moles of gas as an independent parameter for closure coupling. The capillary backstress method was unable to accurately simulate conditions of re-closure of the room. Two methods were found to be accurate enough to approximate the effects of room closure; the boundary backstress method and pressure-time-porosity line interpolation. The boundary backstress method is a more reliable indicator of system behavior due to a theoretical basis for modeling salt deformation as a viscous process. It is a complex method and a detailed calibration process is required. The pressure lines method is thought to be less reliable because the results were skewed towards SANCHO results in simulations where the sequence of gas generation was significantly different from the SANCHO gas-generation rate histories used for closure calibration. This limitation in the pressure lines method is most pronounced at higher gas-generation rates and is relatively insignificant at lower gas-generation rates. Due to its relative simplicity, the pressure lines method is easier to implement in multiphase flow codes and simulations have a shorter execution time
Sakamoto, Noboru; Schaft, Arjan J. van der
2006-01-01
In this report, a method for approximating the stabilizing solution of the Hamilton-Jacobi equation for integrable systems is proposed using symplectic geometry and a Hamiltonian perturbation technique. Using the fact that the Hamiltonian lifted system of an integrable system is also integrable, the
Sakamoto, N.; Schaft, van der A.J.
2006-01-01
In this report, a method for approximating the stabilizing solution of the Hamilton-Jacobi equation for integrable systems is proposed using symplectic geometry and a Hamiltonian perturbation technique. Using the fact that the Hamiltonian lifted system of an integrable system is also integrable, the
Brezzi, Franco; Hughes, T.J.R.; Suli, Endre
2001-01-01
We consider the approximation of elliptic boundary value problems by conforming finite element methods. A model problem, the Poisson equation with Dirichlet boundary conditions, is used to examine the convergence behavior of flux defined on an internal boundary which splits the domain in two. A variational definition of flux, designed to satisfy local conservation laws, is shown to lead to improved rates of convergence.
自治Lienard系统的简化HX方法%Autonomous Lienard Systems Based on Simplified HX Equation Approximation Method
Institute of Scientific and Technical Information of China (English)
赵纬经; 李洪兴
2013-01-01
应用HX方程逼近方法,具体讨论自治Lienard系统的求解,提出这类系统的简化HX方法.使用此方法求解自治Lienard系统时,逐片HX方程的系数表达式得到简化,能够减少其计算步骤,降低其运算的时间和空间复杂度.最后通过一个仿真实验验证了简化HX解法在求解Lienard系统时,具有较高的逼近精度,同时节约了计算时间.%By applying HX equation approximation method, a simplified HX equation approximation method in autonomous Lienard system is proposed. The novel method simplified coefficients of each HX equations, leads to little calculation, and the time complexity and space complexity is reduced. At last, the simulation results show that simplified HX equation approximation method in solving autonomous Lienard system is of high approximation precision, meanwhile the computing time is saved.
Approximate Solutions of Fractional Riccati Equations Using the Adomian Decomposition Method
Directory of Open Access Journals (Sweden)
Fei Wu
2014-01-01
Full Text Available The fractional derivative equation has extensively appeared in various applied nonlinear problems and methods for finding the model become a popular topic. Very recently, a novel way was proposed by Duan (2010 to calculate the Adomian series which is a crucial step of the Adomian decomposition method. In this paper, it was used to solve some fractional nonlinear differential equations.
Champagnat, Nicolas; Faou, Erwan
2010-01-01
We propose extensions and improvements of the statistical analysis of distributed multipoles (SADM) algorithm put forth by Chipot et al. in [6] for the derivation of distributed atomic multipoles from the quantum-mechanical electrostatic potential. The method is mathematically extended to general least-squares problems and provides an alternative approximation method in cases where the original least-squares problem is computationally not tractable, either because of its ill-posedness or its high-dimensionality. The solution is approximated employing a Monte Carlo method that takes the average of a random variable defined as the solutions of random small least-squares problems drawn as subsystems of the original problem. The conditions that ensure convergence and consistency of the method are discussed, along with an analysis of the computational cost in specific instances.
Directory of Open Access Journals (Sweden)
Ali Sevimlican
2010-01-01
Full Text Available He's variational iteration method (VIM is used for solving space and time fractional telegraph equations. Numerical examples are presented in this paper. The obtained results show that VIM is effective and convenient.
Gueguin, Maxime; Hassen, Ghazi; Bleyer, Jérémy; De Buhan, Patrick
2013-01-01
International audience In this contribution, the yield design homogenization method is applied to the evaluation of the ultimate bearing capacity of a purely cohesive soil reinforced by a periodic array of columnar inclusions, made of a purely frictional material (stone column technique). The method is implemented following a three-step procedure. a) First, the numerical determination of the macroscopic strength criterion is performed using the kinematic approach of yield design. b) Second...
McDonald, Stuart
2006-01-01
A stochastic partial differential equation, or SPDE, describes the dynamics of a stochastic process defined on a space-time continuum. This paper provides a new method for solving SPDEs based on the method of lines (MOL). MOL is a technique that has largely been used for numerically solving deterministic partial differential equations (PDEs). MOL works by transforming the PDE into a system of ordinary differential equations (ODEs) by discretizing the spatial dimension of the PDE. The resultin...
Directory of Open Access Journals (Sweden)
Neeraj Tiwari
2014-06-01
Full Text Available Under inclusion probability proportional to size (IPPS sampling, the exact secondorder inclusion probabilities are often very difficult to obtain, and hence variance of the Horvitz- Thompson estimator and Sen-Yates-Grundy estimate of the variance of Horvitz-Thompson estimator are difficult to compute. Hence the researchers developed some alternative variance estimators based on approximations of the second-order inclusion probabilities in terms of the first order inclusion probabilities. We have numerically compared the performance of the various alternative approximate variance estimators using the split method of sample selection
DEFF Research Database (Denmark)
Kimiaeifar, Amin; Lund, Erik; Thomsen, Ole Thybo;
2010-01-01
In this work, an analytical method, which is referred to as Parameter-expansion Method is used to obtain the exact solution for the problem of nonlinear vibrations of an inextensible beam. It is shown that one term in the series expansion is sufficient to obtain a highly accurate solution, which...... is valid for the whole domain of the problem. A comparison of the obtained the numerical solution demonstrates that PEM is effective and convenient for solving such problems. After validation of the obtained results, the system response and stability are also discussed....
THE LOWER APPROXIMATION OF EIGENVALUE BY LUMPED MASS FINITE ELEMENT METHOD
Institute of Scientific and Technical Information of China (English)
Jun Hu; Yun-qing Huang; Hongmei Shen
2004-01-01
In the present paper, we investigate properties of lumped mass finite element method (LFEM hereinafter) eigenvalues of elliptic problems. We propose an equivalent formulation of LFEM and prove that LFEM eigenvalues are smaller than the standard finite element method (SFEM hereinafter) eigenvalues. It is shown, for model eigenvalue problems with uniform meshes, that LFEM eigenvalues are not greater than exact solutions and that they are increasing functions of the number of elements of the triangulation, and numerical examples show that this result equally holds for general problems.
Szalay, Viktor
1999-11-01
The reconstruction of a function from knowing only its values on a finite set of grid points, that is the construction of an analytical approximation reproducing the function with good accuracy everywhere within the sampled volume, is an important problem in all branches of sciences. One such problem in chemical physics is the determination of an analytical representation of Born-Oppenheimer potential energy surfaces by ab initio calculations which give the value of the potential at a finite set of grid points in configuration space. This article describes the rudiments of iterative and direct methods of potential surface reconstruction. The major new results are the derivation, numerical demonstration, and interpretation of a reconstruction formula. The reconstruction formula derived approximates the unknown function, say V, by linear combination of functions obtained by discretizing the continuous distributed approximating functional (DAF) approximation of V over the grid of sampling. The simplest of contracted and ordinary Hermite-DAFs are shown to be sufficient for reconstruction. The linear combination coefficients can be obtained either iteratively or directly by finding the minimal norm least-squares solution of a linear system of equations. Several numerical examples of reconstructing functions of one and two variables, and very different shape are given. The examples demonstrate the robustness, high accuracy, as well as the caveats of the proposed method. As to the mathematical foundation of the method, it is shown that the reconstruction formula can be interpreted as, and in fact is, frame expansion. By recognizing the relevance of frames in determining analytical approximation to potential energy surfaces, an extremely rich and beautiful toolbox of mathematics has come to our disposal. Thus, the simple reconstruction method derived in this paper can be refined, extended, and improved in numerous ways.
A conjugate direction method for approximating the analytic center of a polytope
Megiddo Nimrod; Mizuno Shinji; Kojima Masakazu
1998-01-01
The analytic center of an -dimensional polytope with a nonempty interior is defined as the unique minimizer of the logarithmic potential function over . It is shown that one cycle of a conjugate direction method, applied to the potential function at any such that , generates a point such that .
Approximation for Transient of Nonlinear Circuits Using RHPM and BPES Methods
Directory of Open Access Journals (Sweden)
H. Vazquez-Leal
2013-01-01
Full Text Available The microelectronics area constantly demands better and improved circuit simulation tools. Therefore, in this paper, rational homotopy perturbation method and Boubaker Polynomials Expansion Scheme are applied to a differential equation from a nonlinear circuit. Comparing the results obtained by both techniques revealed that they are effective and convenient.
An Approximate Method for Calculation of Fluid Force and Response of A Circular Cylinder at Lock-in
Institute of Scientific and Technical Information of China (English)
WANG Yi
2008-01-01
In this paper, equations calculating lift force of a rigid circular cylinder at lock-in in uniform flow are deduced in detail. Besides, equations calculating the lift force on a long flexible circular cylinder at lock-in are deduced based on mode analysis of a multi-degree freedom system. The simplified forms of these equations are also given. Furthermore, an approximate method to predict the forces and response of rigid circular cylinders and long flexible circular cylinders at lock-in is introduced in the case of low mass-damping ratio. A method to eliminate one deficiency of these equations is introduced. Comparison with experimental results shows the effectiveness of this approximate method.
Directory of Open Access Journals (Sweden)
Grigis A
2006-01-01
Full Text Available A method for determination and two methods for approximation of the domain of attraction Da(0 of the asymptotically stable zero steady state of an autonomous, ℝ-analytical, discrete dynamical system are presented. The method of determination is based on the construction of a Lyapunov function V, whose domain of analyticity is Da(0. The first method of approximation uses a sequence of Lyapunov functions Vp, which converge to the Lyapunov function V on Da(0. Each Vp defines an estimate Np of Da(0. For any x ∈ Da(0, there exists an estimate which contains x. The second method of approximation uses a ball B(R ⊂ Da(0 which generates the sequence of estimates Mp = f-p(B(R. For any x ∈ Da(0, there exists an estimate which contains x. The cases ||∂0f||<1 and ρ(∂0f < 1 ≤||∂0f|| are treated separately because significant differences occur.
A computational intensive method- Lubrication approximation theory for blade coating process
Directory of Open Access Journals (Sweden)
Saira Bhatti
2016-09-01
Full Text Available This paper presents the analysis of the process of blade coating through a computational intensive method for an incompressible Newtonian fluid along with Magnetohydrodynamics (MHD. The slip between the substrate and the fluid is also taken into account. The nature of the existing steady solutions has been investigated with the help of exact and numerical methods. Those obtained exact solutions include the solutions for the velocity profiles, volumetric flow rate and pressure gradient. The important engineering quantities like maximum pressure, pressure distribution and load are also computed. It is assumed that the relative velocity between the plate and the fluid is proportional to the shear rate at the plate. An external magnetic field is applied normal to the plates. It is observed and concluded that both slip parameter and the magnetic field parameter serve as the controlling parameters in the industrial blade coating process.
Köhler, Christof; Frauenheim, Thomas; Hourahine, Ben; Seifert, Gotthard; Sternberg, Michael
2007-07-01
We report benchmark calculations of the density functional based tight-binding method concerning the magnetic properties of small iron clusters (Fe2 to Fe5) and the Fe13 icosahedron. Energetics and stability with respect to changes of cluster geometry of collinear and noncollinear spin configurations are in good agreement with ab initio results. The inclusion of spin-orbit coupling has been tested for the iron dimer. PMID:17428041
Entropy Viscosity Method for High-Order Approximations of Conservation Laws
Guermond, J. L.
2010-09-17
A stabilization technique for conservation laws is presented. It introduces in the governing equations a nonlinear dissipation function of the residual of the associated entropy equation and bounded from above by a first order viscous term. Different two-dimensional test cases are simulated - a 2D Burgers problem, the "KPP rotating wave" and the Euler system - using high order methods: spectral elements or Fourier expansions. Details on the tuning of the parameters controlling the entropy viscosity are given. © 2011 Springer.
Numerical Methods for Chemically Reacting Fluid Flow Computation under Low-Mach Number Approximation
Arima, Toshiyuki
2006-01-01
A mathematical model of environmental fluid is presented to describe fluid flow motions with large density variations. Moreover the associated numerical methods are discussed. The model of environmental fluid is formulated as an unsteady low-Mach number flow based on the compressible Navier-Stokes equations. For low-Mach number flows, the acoustic effects are assumed to be weak relative to the advection effects. Under this assumption, detailed acoustic effects can be removed fr...
Backman, Ylva; Gardelli, Viktor
2015-01-01
In this study, the age-old distinction between decision method and criterion of rightness, commonly employed in normative ethics, was used to attain a detailed understanding of inter- and intrapersonal variety in students' moral reasoning. A total of 24 Swedish students, 12-15 years of age, were interviewed. Inter- and intrapersonal varieties in…
Foundation of the semiclassical approximation by means of path integral methods
International Nuclear Information System (INIS)
The aim of our study is to find a technically unique semiclassical treatment to describe the collision processes between heavy ions. Thereby it shall be started from a complete quantum mechanical formulation of the collision process. This aim requires: 1. A completely quantum mechanical initial formulation for the whole system, 2. a unique and conceptually clear transition to semiclassics. In order to fulfil the requirements a method is offered which is in closest connection with the Feynman propagator respectively influence functional. (orig./HSI)
Directory of Open Access Journals (Sweden)
S.V. Kryuchkov
2015-03-01
Full Text Available The power of the elliptically polarized electromagnetic radiation absorbed by band-gap graphene in presence of constant magnetic field is calculated. The linewidth of cyclotron absorption is shown to be non-zero even if the scattering is absent. The calculations are performed analytically with the Boltzmann kinetic equation and confirmed numerically with the Monte Carlo method. The dependence of the linewidth of the cyclotron absorption on temperature applicable for a band-gap graphene in the absence of collisions is determined analytically.
A Perceptually Reweighted Mixed-Norm Method for Sparse Approximation of Audio Signals
DEFF Research Database (Denmark)
Christensen, Mads Græsbøll; Sturm, Bob L.
2011-01-01
In this paper, we consider the problem of finding sparse representations of audio signals for coding purposes. In doing so, it is of utmost importance that when only a subset of the present components of an audio signal are extracted, it is the perceptually most important ones. To this end, we...... propose a new iterative algorithm based on two principles: 1) a reweighted l1-norm based measure of sparsity; and 2) a reweighted l2-norm based measure of perceptual distortion. Using these measures, the considered problem is posed as a constrained convex optimization problem that can be solved optimally...... using standard software. A prominent feature of the new method is that it solves a problem that is closely related to the objective of coding, namely rate-distortion optimization. In computer simulations, we demonstrate the properties of the algorithm and its application to real audio signals....
Indian Academy of Sciences (India)
S Unlu; T Babacan; N Cakmak; C Selam
2008-09-01
The violated commutation condition between the total shell model Hamiltonian and Gamow–Teller operator (GT) has been restored by Pyatov method (PM). The considered nuclear model Hamiltonian in PM includes the separable GT residual interaction in ph and pp channels and is differentiated from the traditional schematic model by ℎ0 (restoration term). The influence of the h0 effective interaction on the 2 decay of 48Ca, 76Ge, 82Se, 96Zr, 100Mo, 116Cd, 128,130Te and 136Xe is investigated. All the calculations have been done within the framework of standard QRPA. The results obtained by PM are compared with those of other approaches and experimental data. The influence of the restoration term on the stability of the 2 decay nuclear matrix elements is analysed.
Approximation methods of mixed l 1/H2 optimization problems for MIMO discrete-time systems
Institute of Scientific and Technical Information of China (English)
李昇平
2004-01-01
The mixed l1/H2 optimization problem for MIMO (multiple input-multiple output) discrete-time systems is eonsidered. This problem is formulated as minimizing the l1-norm of a dosed-loop transfer matrix while maintaining the H2-norm of another closed-loop transfer matrix at prescribed level. The continuity property of the optimal value in respect to changes in the H2-norm constraint is studied. The existence of the optimal solutions of mixed l1/H2 problem is proved. Becatse the solution of the mixed l1/H2 problem is based on the scaled-Q method, it avoids the zero interpolation difficulties. The convergent upper and lower bounds can be obtained by solving a sequence of finite dimensional nonlinear programming for which many efficient numerical optimization algorithms exist.
Energy Technology Data Exchange (ETDEWEB)
Maliassov, S.Y. [Texas A& M Univ., College Station, TX (United States)
1996-12-31
An approach to the construction of an iterative method for solving systems of linear algebraic equations arising from nonconforming finite element discretizations with nonmatching grids for second order elliptic boundary value problems with anisotropic coefficients is considered. The technique suggested is based on decomposition of the original domain into nonoverlapping subdomains. The elliptic problem is presented in the macro-hybrid form with Lagrange multipliers at the interfaces between subdomains. A block diagonal preconditioner is proposed which is spectrally equivalent to the original saddle point matrix and has the optimal order of arithmetical complexity. The preconditioner includes blocks for preconditioning subdomain and interface problems. It is shown that constants of spectral equivalence axe independent of values of coefficients and mesh step size.
Indian Academy of Sciences (India)
Kanat Burak Bozdogan; Duygu Ozturk
2010-06-01
This study presents an approximate method based on the continuum approach and transfer matrix method for lateral stability analysis of buildings. In this method, the whole structure is idealized as an equivalent sandwich beam which includes all deformations. The effect of shear deformations of walls has been taken into consideration and incorporated in the formulation of the governing equations. Initially the stability differential equation of this equivalent sandwich beam is presented, and then shape functions for each storey is obtained by the solution of the differential equations. By using boundary conditions and stability storey transfer matrices obtained by shape functions, system buckling load can be calculated. To verify the presented method, four numerical examples have been solved. The results of the samples demonstrate the agreement between the presented method and the other methods given in the literature.
Mike Lonergan; Dave Thompson; Len Thomas; Callan Duck
2011-01-01
1. For British grey seals, as with many pinniped species, population monitoring is implemented by aerial surveys of pups at breeding colonies. Scaling pup counts up to population estimates requires assumptions about population structure; this is straightforward when populations are growing exponentially, but not when growth slows, since it is unclear whether density dependence affects pup survival or fecundity. 2. We present an approximate Bayesian method for fitting pup trajectories, estimat...
Duris, Karol; Tan, Shih-Hau; Lai, Choi-Hong; Sevcovic, Daniel
2015-01-01
Market illiquidity, feedback effects, presence of transaction costs, risk from unprotected portfolio and other nonlinear effects in PDE based option pricing models can be described by solutions to the generalized Black-Scholes parabolic equation with a diffusion term nonlinearly depending on the option price itself. Different linearization techniques such as Newton's method and analytic asymptotic approximation formula are adopted and compared for a wide class of nonlinear Black-Scholes equat...
Directory of Open Access Journals (Sweden)
Taís Quevedo Marcolino
2014-12-01
Full Text Available The Clinical Reasoning Study supported by the American Occupational Therapy Association/AOTA and the American Occupational Therapy Foundation/AOTF in the United States in the late 1980s, had inaugurated the scientific production in the field and offered an initial framework on clinical reasoning for understanding and conducting clinical cases in Occupational Therapy. Most of the researches in this field have focused on reasoning processes, and point out the need to understand the contents of clinical thoughts, or how occupational therapists act and elaborate hypotheses, based on their background knowledge, in order to produce an explanatory theory. In this direction, this article presents the results of two studies from the author focused on understanding aspects of clinical reasoning of occupational therapists who work sustained by Occupational Therapy Dynamic Method/ MTOD, highlighting similarities and differences on diagnostic and procedural reasoning. The discussion points out need to expand the production of this type of research, in particular with Brazilian professionals, as well as the dissemination and study of this subject in the initial and continuing training of occupational therapists.
A New Method in the Location Problem using Fuzzy Evidential Reasoning
Directory of Open Access Journals (Sweden)
Sh. Rahgan
2012-11-01
Full Text Available One of the most important factors leading to the success of a company is its location. Branches have a strategic importance on an organization’s performance and its competitiveness. The purpose of this study is to present a decision-making model for selecting the most appropriate location for a bank branch. This research is the first study in the bank branch location researches considering various types of uncertainties. This model involves both quantitative and qualitative attributes as well as various types of uncertainty. So, we propose a methodology by integrating the fuzzy AHP and Evidential Reasoning approach. The fuzzy extent analysis is used to determine the weights of attributes and sub-attributes and the interval ER algorithm is used to rank the alternatives. This methodology can be used to help the decision makers, because it is capable of handling incomplete and imprecise judgments. We have demonstrated the applicability of the methodology through a case study.
A Method to Identify and Analyze Biological Programs through Automated Reasoning
Kugler, Hillel; Smith, Austin; Martello, Graziano; Emmott, Stephen
2016-01-01
Predictive biology is elusive because rigorous, data-constrained, mechanistic models of complex biological systems are difficult to derive and validate. Current approaches tend to construct and examine static interaction network models, which are descriptively rich but often lack explanatory and predictive power, or dynamic models that can be simulated to reproduce known behavior. However, in such approaches implicit assumptions are introduced as typically only one mechanism is considered, and exhaustively investigating all scenarios is impractical using simulation. To address these limitations, we present a methodology based on automated formal reasoning, which permits the synthesis and analysis of the complete set of logical models consistent with experimental observations. We test hypotheses against all candidate models, and remove the need for simulation by characterizing and simultaneously analyzing all mechanistic explanations of observed behavior. Our methodology transforms knowledge of complex biological processes from sets of possible interactions and experimental observations to precise, predictive biological programs governing cell function. PMID:27668090
Directory of Open Access Journals (Sweden)
Jitpeera Thanyarat
2011-01-01
Full Text Available We introduce a new iterative method for finding a common element of the set of solutions for mixed equilibrium problem, the set of solutions of the variational inequality for a -inverse-strongly monotone mapping, and the set of fixed points of a family of finitely nonexpansive mappings in a real Hilbert space by using the viscosity and Cesàro mean approximation method. We prove that the sequence converges strongly to a common element of the above three sets under some mind conditions. Our results improve and extend the corresponding results of Kumam and Katchang (2009, Peng and Yao (2009, Shimizu and Takahashi (1997, and some authors.
Anisimova, Maria; Gil, Manuel; Dufayard, Jean-François; Dessimoz, Christophe; Gascuel, Olivier
2011-01-01
Phylogenetic inference and evaluating support for inferred relationships is at the core of many studies testing evolutionary hypotheses. Despite the popularity of nonparametric bootstrap frequencies and Bayesian posterior probabilities, the interpretation of these measures of tree branch support remains a source of discussion. Furthermore, both methods are computationally expensive and become prohibitive for large data sets. Recent fast approximate likelihood-based measures of branch supports (approximate likelihood ratio test [aLRT] and Shimodaira–Hasegawa [SH]-aLRT) provide a compelling alternative to these slower conventional methods, offering not only speed advantages but also excellent levels of accuracy and power. Here we propose an additional method: a Bayesian-like transformation of aLRT (aBayes). Considering both probabilistic and frequentist frameworks, we compare the performance of the three fast likelihood-based methods with the standard bootstrap (SBS), the Bayesian approach, and the recently introduced rapid bootstrap. Our simulations and real data analyses show that with moderate model violations, all tests are sufficiently accurate, but aLRT and aBayes offer the highest statistical power and are very fast. With severe model violations aLRT, aBayes and Bayesian posteriors can produce elevated false-positive rates. With data sets for which such violation can be detected, we recommend using SH-aLRT, the nonparametric version of aLRT based on a procedure similar to the Shimodaira–Hasegawa tree selection. In general, the SBS seems to be excessively conservative and is much slower than our approximate likelihood-based methods. PMID:21540409
Qin, Cheng-Zhi; Wu, Xue-Wei; Jiang, Jing-Chao; Zhu, A.-Xing
2016-08-01
Application of digital terrain analysis (DTA), which is typically a modeling process involving workflow building, relies heavily on DTA domain knowledge of the match between the algorithm (and its parameter settings) and the application context (including the target task, the terrain in the study area, the DEM resolution, etc.), which is referred to as application-context knowledge. However, existing DTA-assisted tools often cannot use application-context knowledge because this type of DTA knowledge has not been formalized to be available for inference in these tools. This situation makes the DTA workflow-building process difficult for users, especially non-expert users. This paper proposes a case-based formalization for DTA application-context knowledge and a corresponding case-based reasoning method. A case in this context consists of a series of indices that formalize the DTA application-context knowledge and the corresponding similarity calculation methods for case-based reasoning. A preliminary experiment to determine the catchment area threshold for extracting drainage networks has been conducted to evaluate the performance of the proposed method. In the experiment, 124 cases of drainage network extraction (50 for evaluation and 74 for reasoning) were prepared from peer-reviewed journal articles. Preliminary evaluation shows that the proposed case-based method is a suitable way to use DTA application-context knowledge to achieve a marked reduction in the modeling burden for users.
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
The problem of the process of coupled diffusion and reaction in catalyst pellets is considered for the case of second and half order reactions. The Adomian decomposition method is used to solve the non-linear model. For the second, half and first order reactions, analytical approximate solutions are obtained. The variation of reactant concentration in the catalyst pellet and the effectiveness factors at φ＜10 are determined and compared with those by the BAND's finite difference numerical method developed by Newman. At lower values of φ, the decomposition solution with 3 terms gives satisfactory agreement with the numerical solution; at higher values of φ, as the term number in the decomposition method is increased, an acceptable agreement between the two methods is achieved. In general, the solution with 6 terms gives a satisfactory agreement.
Directory of Open Access Journals (Sweden)
Wei Li
2012-01-01
Full Text Available An extended finite element method (XFEM for the forward model of 3D optical molecular imaging is developed with simplified spherical harmonics approximation (SPN. In XFEM scheme of SPN equations, the signed distance function is employed to accurately represent the internal tissue boundary, and then it is used to construct the enriched basis function of the finite element scheme. Therefore, the finite element calculation can be carried out without the time-consuming internal boundary mesh generation. Moreover, the required overly fine mesh conforming to the complex tissue boundary which leads to excess time cost can be avoided. XFEM conveniences its application to tissues with complex internal structure and improves the computational efficiency. Phantom and digital mouse experiments were carried out to validate the efficiency of the proposed method. Compared with standard finite element method and classical Monte Carlo (MC method, the validation results show the merits and potential of the XFEM for optical imaging.
Directory of Open Access Journals (Sweden)
S.Padma
2013-06-01
Full Text Available A new wavelet based approximation method for solving the second order differential equations arising science and engineering is presented in this paper. Such differential equation is often applied to model phenomena in various fields of science and engineering. In this study, shifted second kind Chebyshev wavelet (CW operational matrices of derivatives is introduced and applied for solvingthe second order differential equations with various initial conditions. The key idea for getting the numerical solutions for these equations is to convert the differential equations (linear or nonlinear to a system of linear or nonlinear algebraic equations in the unknown expansion coefficients. Some illustrative examples are given to demonstrate the validity and applicability of the proposed method. The power of the manageable method is confirmed. Moreover the use of the shifted second kind Chebyshev wavelet method (CWM is found to be simple, flexible, efficient, small computation costs and computationally attractive.
Relations between Inductive Reasoning and Deductive Reasoning
Heit, Evan; Rotello, Caren M.
2010-01-01
One of the most important open questions in reasoning research is how inductive reasoning and deductive reasoning are related. In an effort to address this question, we applied methods and concepts from memory research. We used 2 experiments to examine the effects of logical validity and premise-conclusion similarity on evaluation of arguments.…
DEFF Research Database (Denmark)
Kildemoes, Helle Wallach; Hendriksen, Carsten; Morten, Andersen
2011-01-01
ABSTRACT Purpose To develop a pharmacoepidemiologic method for drug utilization analysis according to indication, gender, and age by means of register-based information. Statin utilization in 2005 was applied as an example. Methods Following the recommendations for statin therapy, we constructed ...... into prescription patterns of statins. The method can be implemented for other drug categories and could be useful for studying trends in drug utilization, differential drug adherence, and cross-national comparisons......ABSTRACT Purpose To develop a pharmacoepidemiologic method for drug utilization analysis according to indication, gender, and age by means of register-based information. Statin utilization in 2005 was applied as an example. Methods Following the recommendations for statin therapy, we constructed...... an indication hierarchy with eight mutually exclusive levels of register markers of cardiovascular disease and diabetes. Danish residents, as of January 1, 1996, were followed at the individual level in nationwide registers with respect to dispensed prescriptions of cardiovascular drugs and antidiabetics (1996...
Yzer, Marco; Weisman, Susan; Mejia, Nicole; Hennrikus, Deborah; Choi, Kelvin; DeSimone, Susan
2015-08-01
Blue-collar workers typically have high rates of tobacco use but low rates of using tobacco cessation resources available through their health benefits. Interventions to motivate blue-collar tobacco users to use effective cessation support are needed. Reasoned action theory is useful in this regard as it can identify the beliefs that shape tobacco cessation benefit use intentions. However, conventional reasoned action research cannot speak to how those beliefs can best be translated into intervention messages. In the present work, we expand the reasoned action approach by adding additional qualitative inquiry to better understand blue-collar smokers' beliefs about cessation benefit use. Across three samples of unionized blue-collar tobacco users, we identified (1) the 35 attitudinal, normative, and control beliefs that represented tobacco users' belief structure about cessation benefit use; (2) instrumental attitude as most important in explaining cessation intention; (3) attitudinal beliefs about treatment options' efficacy, health effects, and monetary implications of using benefits as candidates for message design; (4) multiple interpretations of cessation beliefs (e.g., short and long-term health effects); and (5) clear implications of these interpretations for creative message design. Taken together, the findings demonstrate how a mixed-method reasoned action approach can inform interventions that promote the use of tobacco cessation health benefits.
Yzer, Marco; Weisman, Susan; Mejia, Nicole; Hennrikus, Deborah; Choi, Kelvin; DeSimone, Susan
2015-08-01
Blue-collar workers typically have high rates of tobacco use but low rates of using tobacco cessation resources available through their health benefits. Interventions to motivate blue-collar tobacco users to use effective cessation support are needed. Reasoned action theory is useful in this regard as it can identify the beliefs that shape tobacco cessation benefit use intentions. However, conventional reasoned action research cannot speak to how those beliefs can best be translated into intervention messages. In the present work, we expand the reasoned action approach by adding additional qualitative inquiry to better understand blue-collar smokers' beliefs about cessation benefit use. Across three samples of unionized blue-collar tobacco users, we identified (1) the 35 attitudinal, normative, and control beliefs that represented tobacco users' belief structure about cessation benefit use; (2) instrumental attitude as most important in explaining cessation intention; (3) attitudinal beliefs about treatment options' efficacy, health effects, and monetary implications of using benefits as candidates for message design; (4) multiple interpretations of cessation beliefs (e.g., short and long-term health effects); and (5) clear implications of these interpretations for creative message design. Taken together, the findings demonstrate how a mixed-method reasoned action approach can inform interventions that promote the use of tobacco cessation health benefits. PMID:25975798
Giese, Timothy J; York, Darrin M
2010-12-28
We extend the Kohn-Sham potential energy expansion (VE) to include variations of the kinetic energy density and use the VE formulation with a 6-31G* basis to perform a "Jacob's ladder" comparison of small molecule properties using density functionals classified as being either LDA, GGA, or meta-GGA. We show that the VE reproduces standard Kohn-Sham DFT results well if all integrals are performed without further approximation, and there is no substantial improvement in using meta-GGA functionals relative to GGA functionals. The advantages of using GGA versus LDA functionals becomes apparent when modeling hydrogen bonds. We furthermore examine the effect of using integral approximations to compute the zeroth-order energy and first-order matrix elements, and the results suggest that the origin of the short-range repulsive potential within self-consistent charge density-functional tight-binding methods mainly arises from the approximations made to the first-order matrix elements.
Directory of Open Access Journals (Sweden)
Mike Lonergan
2011-01-01
Full Text Available For British grey seals, as with many pinniped species, population monitoring is implemented by aerial surveys of pups at breeding colonies. Scaling pup counts up to population estimates requires assumptions about population structure; this is straightforward when populations are growing exponentially but not when growth slows, since it is unclear whether density dependence affects pup survival or fecundity. We present an approximate Bayesian method for fitting pup trajectories, estimating adult population size and investigating alternative biological models. The method is equivalent to fitting a density-dependent Leslie matrix model, within a Bayesian framework, but with the forms of the density-dependent effects as outputs rather than assumptions. It requires fewer assumptions than the state space models currently used and produces similar estimates. We discuss the potential and limitations of the method and suggest that this approach provides a useful tool for at least the preliminary analysis of similar datasets.
Guo, Chengan; Yang, Qingshan
2015-07-01
Finding the optimal solution to the constrained l0 -norm minimization problems in the recovery of compressive sensed signals is an NP-hard problem and it usually requires intractable combinatorial searching operations for getting the global optimal solution, unless using other objective functions (e.g., the l1 norm or lp norm) for approximate solutions or using greedy search methods for locally optimal solutions (e.g., the orthogonal matching pursuit type algorithms). In this paper, a neurodynamic optimization method is proposed to solve the l0 -norm minimization problems for obtaining the global optimum using a recurrent neural network (RNN) model. For the RNN model, a group of modified Gaussian functions are constructed and their sum is taken as the objective function for approximating the l0 norm and for optimization. The constructed objective function sets up a convexity condition under which the neurodynamic system is guaranteed to obtain the globally convergent optimal solution. An adaptive adjustment scheme is developed for improving the performance of the optimization algorithm further. Extensive experiments are conducted to test the proposed approach in this paper and the output results validate the effectiveness of the new method. PMID:25122603
Discretizing of linear systems with time-delay Using method of Euler’s and Tustin’s approximations
Directory of Open Access Journals (Sweden)
Bemri H’mida
2015-03-01
Full Text Available Delays deteriorate the control performance and could destabilize the overall system in the theory of discretetime signals and dynamic systems. Whenever a computer is used in measurement, signal processing or control applications, the data as seen from the computer and systems involved are naturally discrete-time because a computer executes program code at discrete points of time. Theory of discrete-time dynamic signals and systems is useful in design and analysis of control systems, signal filters, state estimators and model estimation from time-series of process data system identification. In this paper, a new approximated discretization method and digital design for control systems with delays is proposed. System is transformed to a discrete-time model with time delays. To implement the digital modeling, we used the z-transfer functions matrix which is a useful model type of discrete-time systems, being analogous to the Laplace-transform for continuous-time systems. The most important use of the z-transform is for defining z-transfer functions matrix is employed to obtain an extended discrete-time. The proposed method can closely approximate the step response of the original continuous timedelayed control system by choosing various of energy loss level. Illustrative example is simulated to demonstrate the effectiveness of the developed method.
Energy Technology Data Exchange (ETDEWEB)
Regnier, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); CEA, DAM, DIF, Arpajon (France); Verriere, M. [CEA, DAM, DIF, Arpajon (France); Dubray, N. [CEA, DAM, DIF, Arpajon (France); Schunck, N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-11-30
In this study, we describe the software package FELIX that solves the equations of the time-dependent generator coordinate method (TDGCM) in NN-dimensions (N ≥ 1) under the Gaussian overlap approximation. The numerical resolution is based on the Galerkin finite element discretization of the collective space and the Crank–Nicolson scheme for time integration. The TDGCM solver is implemented entirely in C++. Several additional tools written in C++, Python or bash scripting language are also included for convenience. In this paper, the solver is tested with a series of benchmarks calculations. We also demonstrate the ability of our code to handle a realistic calculation of fission dynamics.
Regnier, D.; Verrière, M.; Dubray, N.; Schunck, N.
2016-03-01
We describe the software package FELIX that solves the equations of the time-dependent generator coordinate method (TDGCM) in N-dimensions (N ≥ 1) under the Gaussian overlap approximation. The numerical resolution is based on the Galerkin finite element discretization of the collective space and the Crank-Nicolson scheme for time integration. The TDGCM solver is implemented entirely in C++. Several additional tools written in C++, Python or bash scripting language are also included for convenience. In this paper, the solver is tested with a series of benchmarks calculations. We also demonstrate the ability of our code to handle a realistic calculation of fission dynamics.
Regnier, D; Dubray, N; Schunck, N
2015-01-01
We describe the software package FELIX that solves the equations of the time-dependent generator coordinate method (TDGCM) in N-dimensions (N $\\geq$ 1) under the Gaussian overlap approximation. The numerical resolution is based on the Galerkin finite element discretization of the collective space and the Crank-Nicolson scheme for time integration. The TDGCM solver is implemented entirely in C++. Several additional tools written in C++, Python or bash scripting language are also included for convenience. In this paper, the solver is tested with a series of benchmarks calculations. We also demonstrate the ability of our code to handle a realistic calculation of fission dynamics.
Gómez-Pérez, José Manuel; Erdmann, M; Greaves, M; Corcho, Oscar
2013-01-01
Enabling Subject Matter Experts (SMEs) to formulate knowledge without the intervention of Knowledge Engineers (KEs) requires providing SMEs with methods and tools that abstract the underlying knowledge representation and allow them to focus on modeling activities. Bridging the gap between SME-authored models and their representation is challenging, especially in the case of complex knowledge types like processes, where aspects like frame management, data, and control flow need to be addressed...
Ibáñez, Javier; Hernández, Vicente
2011-03-01
Differential Matrix Riccati Equations (DMREs) appear in several branches of science such as applied physics and engineering. For example, these equations play a fundamental role in control theory, optimal control, filtering and estimation, decoupling and order reduction, etc. In this paper a new method based on a theorem proved in this paper is described for solving DMREs by a piecewise-linearized approach. This method is applied for developing two block-oriented algorithms based on diagonal Padé approximants. MATLAB versions of the above algorithms are developed, comparing, under equal conditions, accuracy and computational costs with other piecewise-linearized algorithms implemented by the authors. Experimental results show the advantages of solving stiff or non-stiff DMREs by the implemented algorithms.
Dalmasse, K; Gibson, S E; Fan, Y; Flyer, N
2016-01-01
The Coronal Multichannel Polarimeter (CoMP) routinely performs coronal polarimetric measurements using the Fe XIII 10747 $\\AA$ and 10798 $\\AA$ lines, which are sensitive to the coronal magnetic field. However, inverting such polarimetric measurements into magnetic field data is a difficult task because the corona is optically thin at these wavelengths and the observed signal is therefore the integrated emission of all the plasma along the line of sight. To overcome this difficulty, we take on a new approach that combines a parameterized 3D magnetic field model with forward modeling of the polarization signal. For that purpose, we develop a new, fast and efficient, optimization method for model-data fitting: the Radial-basis-functions Optimization Approximation Method (ROAM). Model-data fitting is achieved by optimizing a user-specified log-likelihood function that quantifies the differences between the observed polarization signal and its synthetic/predicted analogue. Speed and efficiency are obtained by comb...
Fletcher, Logan; Carruthers, Peter
2012-01-01
This article considers the cognitive architecture of human meta-reasoning: that is, metacognition concerning one's own reasoning and decision-making. The view we defend is that meta-reasoning is a cobbled-together skill comprising diverse self-management strategies acquired through individual and cultural learning. These approximate the monitoring-and-control functions of a postulated adaptive system for metacognition by recruiting mechanisms that were designed for quite other purposes.
2015-01-01
How can we advance knowledge? Which methods do we need in order to make new discoveries? How can we rationally evaluate, reconstruct and offer discoveries as a means of improving the ‘method’ of discovery itself? And how can we use findings about scientific discovery to boost funding policies, thus fostering a deeper impact of scientific discovery itself? The respective chapters in this book provide readers with answers to these questions. They focus on a set of issues that are essential to the development of types of reasoning for advancing knowledge, such as models for both revolutionary findings and paradigm shifts; ways of rationally addressing scientific disagreement, e.g. when a revolutionary discovery sparks considerable disagreement inside the scientific community; frameworks for both discovery and inference methods; and heuristics for economics and the social sciences.
Institute of Scientific and Technical Information of China (English)
Alexandre Ern; Annette F.Stephansen
2008-01-01
We propose and analyze a posteriori energy-norm error estimates for weighted interior penalty discontinuous Galerkin approximations of advection-diffusion-reaction equations with heterogeneous and anisotropic diffusion.The weights,which play a key role in the analysis.depend on the diffusion tensor and are used to formulate the consistency terms in the discontinuous Galerkin method.The error upper bounds,in which all the constants are specified.consist of three terms:a residual estimator which depends only on the elementwise fluctuation of the discrete solution residual,a diffusive flux estimator where the weights used in the method enter explicitly,and a non-conforming estimator which is nonzero because of the use of discontinuous finite element spaces.The three estimators can be bounded locally by the approximation error.A particular attention is given to the dependency on problem parameters of the constants in the local lower error bounds,For moderate advection.it.is shown that full robustness with respect to diffusion heterogeneities is achieved owing to the specific design of the weights in the discontinuous Galerkin method,while diffusion anisotropies remain purely local and impact the constants through the square root of the condition number of the diffusion tensor.For dominant advection,the local lower error bounds can be written with constants involving a cut-off for the ratio of local mesh size to the reciprocal of the square root of the lowest local eignevalue of the diffusion tensor.
Case-Based Reasoning Method in Cost Estimation of Drilling Wells
Hossein Shams Mianaei; Seyed Hossein Iranmanesh
2013-01-01
Aim of study is the cost estimation of drilling6T8T 6T8Twells6T8T 6T8Tusing6T Case-Based 6TReasoning6T8T (CBR) method which6T8T is created based6T8T 6T8Ton6T8T 6T8Tthe6T8T 6T8Tviewpoint of using presented6T8T 6T8Tsolutions6T8T 6T8Tfor6T8T 6T8Tprevious6T8T 6T8Tsolved6T8T 6T8Tproblems6T8T in order 6T8Tto solve6T8T new 6T8Tsimilar problems6T8T. 6T8TIn companies6T8T 6T8Tor6T8T 6T8Torganizations6T8T which 6T8Tcost estimation, scheduling,6T8T 6T8Tdesign6T8T, planning 6T8Tand project activities6T8T ...
Approximate iterative algorithms
Almudevar, Anthony Louis
2014-01-01
Iterative algorithms often rely on approximate evaluation techniques, which may include statistical estimation, computer simulation or functional approximation. This volume presents methods for the study of approximate iterative algorithms, providing tools for the derivation of error bounds and convergence rates, and for the optimal design of such algorithms. Techniques of functional analysis are used to derive analytical relationships between approximation methods and convergence properties for general classes of algorithms. This work provides the necessary background in functional analysis a
Reza Khoshravan Azar, Mohammad; Emami Satellou, Ali Akbar; Shishesaz, Mohammad; Salavati, Bahram
2013-04-01
Given the increasing use of composite materials in various industries, oil and gas industry also requires that more attention should be paid to these materials. Furthermore, due to variation in choice of materials, the materials needed for the mechanical strength, resistance in critical situations such as fire, costs and other priorities of the analysis carried out on them and the most optimal for achieving certain goals, are introduced. In this study, we will try to introduce appropriate choice for use in the natural gas transmission composite pipelines. Following a 4-layered filament-wound (FW) composite pipe will consider an offer our analyses under internal pressure. The analyses' results will be calculated for different combinations of angles 15 deg, 30 deg, 45 deg, 55 deg, 60 deg, 75 deg, and 80 deg. Finally, we will compare the calculated values and the optimal angle will be gained by using the Approximation methods. It is explained that this layering is as the symmetrical. PMID:24891748
International Nuclear Information System (INIS)
The assessment of building energy efficiency is one of the most effective measures for reducing building energy consumption. This paper proposes a holistic method (HMEEB) for assessing and certifying energy efficiency of buildings based on the D-S (Dempster-Shafer) theory of evidence and the Evidential Reasoning (ER) approach. HMEEB has three main features: (i) it provides both a method to assess and certify building energy efficiency, and exists as an analytical tool to identify improvement opportunities; (ii) it combines a wealth of information on building energy efficiency assessment, including identification of indicators and a weighting mechanism; and (iii) it provides a method to identify and deal with inherent uncertainties within the assessment procedure. This paper demonstrates the robustness, flexibility and effectiveness of the proposed method, using two examples to assess the energy efficiency of two residential buildings, both located in the ‘Hot Summer and Cold Winter’ zone in China. The proposed certification method provides detailed recommendations for policymakers in the context of carbon emission reduction targets and promoting energy efficiency in the built environment. The method is transferable to other countries and regions, using an indicator weighting system to modify local climatic, economic and social factors. - Highlights: ► Assessing energy efficiency of buildings holistically; ► Applying the D-S (Dempster-Shafer) theory of evidence and the Evidential Reasoning (ER) approach; ► Involving large information and uncertainties in the energy efficiency decision-making process. ► rigorous measures for policymakers to meet carbon emission reduction targets.
Yi, Longtao; Sun, Tianxi; Wang, Kai; Qin, Min; Yang, Kui; Wang, Jinbang; Liu, Zhiguo
2016-08-01
Confocal three-dimensional micro X-ray fluorescence (3D MXRF) is an excellent surface analysis technology. For a confocal structure, only the X-rays from the confocal volume can be detected. Confocal 3D MXRF has been widely used for analysing elements, the distribution of elements and 3D image of some special samples. However, it has rarely been applied to analysing surface topography by surface scanning. In this paper, a confocal 3D MXRF technology based on polycapillary X-ray optics was proposed for determining surface topography. A corresponding surface adaptive algorithm based on a progressive approximation method was designed to obtain surface topography. The surface topography of the letter "R" on a coin of the People's Republic of China and a small pit on painted pottery were obtained. The surface topography of the "R" and the pit are clearly shown in the two figures. Compared with the method in our previous study, it exhibits a higher scanning efficiency. This approach could be used for two-dimensional (2D) elemental mapping or 3D elemental voxel mapping measurements as an auxiliary method. It also could be used for analysing elemental mapping while obtaining the surface topography of a sample in 2D elemental mapping measurement.
Büsing, Henrik
2013-04-01
Two-phase flow in porous media occurs in various settings, such as the sequestration of CO2 in the subsurface, radioactive waste management, the flow of oil or gas in hydrocarbon reservoirs, or groundwater remediation. To model the sequestration of CO2, we consider a fully coupled formulation of the system of nonlinear, partial differential equations. For the solution of this system, we employ the Box method after Huber & Helmig (2000) for the space discretization and the fully implicit Euler method for the time discretization. After linearization with Newton's method, it remains to solve a linear system in every Newton step. We compare different iterative methods (BiCGStab, GMRES, AGMG, c.f., [Notay (2012)]) combined with different preconditioners (ILU0, ASM, Jacobi, and AMG as preconditioner) for the solution of these systems. The required Jacobians can be obtained elegantly with automatic differentiation (AD) [Griewank & Walther (2008)], a source code transformation providing exact derivatives. We compare the performance of the different iterative methods with their respective preconditioners for these linear systems. Furthermore, we analyze linear systems obtained by approximating the Jacobian with finite differences in terms of Newton steps per time step, steps of the iterative solvers and the overall solution time. Finally, we study the influence of heterogeneities in permeability and porosity on the performance of the iterative solvers and their robustness in this respect. References [Griewank & Walther(2008)] Griewank, A. & Walther, A., 2008. Evaluating Derivatives: Principles and Techniques of Algorithmic Differentiation, SIAM, Philadelphia, PA, 2nd edn. [Huber & Helmig(2000)] Huber, R. & Helmig, R., 2000. Node-centered finite volume discretizations for the numerical simulation of multiphase flow in heterogeneous porous media, Computational Geosciences, 4, 141-164. [Notay(2012)] Notay, Y., 2012. Aggregation-based algebraic multigrid for convection
Niven, Ivan
2008-01-01
This self-contained treatment originated as a series of lectures delivered to the Mathematical Association of America. It covers basic results on homogeneous approximation of real numbers; the analogue for complex numbers; basic results for nonhomogeneous approximation in the real case; the analogue for complex numbers; and fundamental properties of the multiples of an irrational number, for both the fractional and integral parts.The author refrains from the use of continuous fractions and includes basic results in the complex case, a feature often neglected in favor of the real number discuss
Frozen Gaussian approximation-based two-level methods for multi-frequency Schrödinger equation
Lorin, E.; Yang, X.
2016-10-01
In this paper, we develop two-level numerical methods for the time-dependent Schrödinger equation (TDSE) in multi-frequency regime. This work is motivated by attosecond science (Corkum and Krausz, 2007), which refers to the interaction of short and intense laser pulses with quantum particles generating wide frequency spectrum light, and allowing for the coherent emission of attosecond pulses (1 attosecond=10-18 s). The principle of the proposed methods consists in decomposing a wavefunction into a low/moderate frequency (quantum) contribution, and a high frequency contribution exhibiting a semi-classical behavior. Low/moderate frequencies are computed through the direct solution to the quantum TDSE on a coarse mesh, and the high frequency contribution is computed by frozen Gaussian approximation (Herman and Kluk, 1984). This paper is devoted to the derivation of consistent, accurate and efficient algorithms performing such a decomposition and the time evolution of the wavefunction in the multi-frequency regime. Numerical simulations are provided to illustrate the accuracy and efficiency of the derived algorithms.
Institute of Scientific and Technical Information of China (English)
宋爽; 那日萨; 张杨
2014-01-01
依据消费者心理学及品牌行为理论，从消费者感知质量、感知价值、品牌声誉、期望达成度4个维度建立了品牌转换意向模型；通过对网络消费者在线评论中评价词、情感词的提取和语义分析，结合模糊情感语料库和品牌转换意向推理规则，模糊推理出消费者品牌转换意向，进而推理出消费者的品牌转换意向的转换类型。以淘宝网上4种化妆品为例进行消费者品牌转换意向研究，得到较合理的结论并给予营销性建议，验证了所提方法的有效性。%Based on consumer psychology and experiential marketing theory,a model of customer switching intention was established from four dimensions:perceived quality,perceived value,brand reputation and expectation.Then se-mantic analysis on the valuation words and emotional words extracted from the consumer online reviews was made.Fur-thermore,combined with fuzzy sentiment corpus and fuzzy inference,the consumer's brand switching intention was computed,and the customer's switching intention types was identified.Finally,an experimental study with the case of four types of cosmetics on the TaoBao site was carried out,and reasonable conclusions and some marketing advices were obtained,which all verify the validity of the method.
Rational offset approximation of rational Bézier curves
Institute of Scientific and Technical Information of China (English)
CHENG Min; WANG Guo-jin
2006-01-01
The problem of parametric speed approximation of a rational curve is raised in this paper. Offset curves are widely used in various applications. As for the reason that in most cases the offset curves do not preserve the same polynomial or rational polynomial representations, it arouses difficulty in applications. Thus approximation methods have been introduced to solve this problem. In this paper, it has been pointed out that the crux of offset curve approximation lies in the approximation of parametric speed. Based on the Jacobi polynomial approximation theory with endpoints interpolation, an algebraic rational approximation algorithm of offset curve, which preserves the direction of normal, is presented.
J. van Benthem
2015-01-01
In this article, nonstandard reasoning refers to the proliferation of reasoning styles investigated in modern logic beyond its traditional agenda. After a brief statement of standard logical approaches to consequence, we describe motivations for new systems. These include not only inference patterns
Negara, Ardiansyah
2015-05-01
Anisotropy of hydraulic properties of the subsurface geologic formations is an essential feature that has been established as a consequence of the different geologic processes that undergo during the longer geologic time scale. With respect to subsurface reservoirs, in many cases, anisotropy plays significant role in dictating the direction of flow that becomes no longer dependent only on driving forces like the pressure gradient and gravity but also on the principal directions of anisotropy. Therefore, there has been a great deal of motivation to consider anisotropy into the subsurface flow and transport models. In this dissertation, we present subsurface flow modeling in single and dual continuum anisotropic porous media, which include the single-phase groundwater flow coupled with the solute transport in anisotropic porous media, the two-phase flow with gravity effect in anisotropic porous media, and the natural gas flow in anisotropic shale reservoirs. We have employed the multipoint flux approximation (MPFA) method to handle anisotropy in the flow model. The MPFA method is designed to provide correct discretization of the flow equations for general orientation of the principal directions of the permeability tensor. The implementation of MPFA method is combined with the experimenting pressure field approach, a newly developed technique that enables the solution of the global problem breaks down into the solution of multitude of local problems. The numerical results of the study demonstrate the significant effects of anisotropy of the subsurface formations. For the single-phase groundwater flow coupled with the solute transport modeling in anisotropic porous media, the results shows the strong impact of anisotropy on the pressure field and the migration of the solute concentration. For the two-phase flow modeling with gravity effect in anisotropic porous media, it is observed that the buoyancy-driven flow, which emerges due to the density differences between the
Energy Technology Data Exchange (ETDEWEB)
Belendez, A [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Pascual, C [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, E [Departamento de Optica, FarmacologIa y AnatomIa, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Neipp, C [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Belendez, T [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)
2008-02-15
A modified He's homotopy perturbation method is used to calculate higher-order analytical approximate solutions to the relativistic and Duffing-harmonic oscillators. The He's homotopy perturbation method is modified by truncating the infinite series corresponding to the first-order approximate solution before introducing this solution in the second-order linear differential equation, and so on. We find this modified homotopy perturbation method works very well for the whole range of initial amplitudes, and the excellent agreement of the approximate frequencies and periodic solutions with the exact ones has been demonstrated and discussed. The approximate formulae obtained show excellent agreement with the exact solutions, and are valid for small as well as large amplitudes of oscillation, including the limiting cases of amplitude approaching zero and infinity. For the relativistic oscillator, only one iteration leads to high accuracy of the solutions with a maximal relative error for the approximate frequency of less than 1.6% for small and large values of oscillation amplitude, while this relative error is 0.65% for two iterations with two harmonics and as low as 0.18% when three harmonics are considered in the second approximation. For the Duffing-harmonic oscillator the relative error is as low as 0.078% when the second approximation is considered. Comparison of the result obtained using this method with those obtained by the harmonic balance methods reveals that the former is very effective and convenient.
Karassiov, V. P.; A. A. Gusev; Vinitsky, S. I.
2001-01-01
We compare exact and SU(2)-cluster approximate calculation schemes to determine dynamics of the second-harmonic generation model using its reformulation in terms of a polynomial Lie algebra $su_{pd}(2)$ and related spectral representations of the model evolution operator realized in algorithmic forms. It enabled us to implement computer experiments exhibiting a satisfactory accuracy of the cluster approximations in a large range of characteristic model parameters.
Approximate Representations and Approximate Homomorphisms
Moore, Cristopher
2010-01-01
Approximate algebraic structures play a defining role in arithmetic combinatorics and have found remarkable applications to basic questions in number theory and pseudorandomness. Here we study approximate representations of finite groups: functions f:G -> U_d such that Pr[f(xy) = f(x) f(y)] is large, or more generally Exp_{x,y} ||f(xy) - f(x)f(y)||^2$ is small, where x and y are uniformly random elements of the group G and U_d denotes the unitary group of degree d. We bound these quantities in terms of the ratio d / d_min where d_min is the dimension of the smallest nontrivial representation of G. As an application, we bound the extent to which a function f : G -> H can be an approximate homomorphism where H is another finite group. We show that if H's representations are significantly smaller than G's, no such f can be much more homomorphic than a random function. We interpret these results as showing that if G is quasirandom, that is, if d_min is large, then G cannot be embedded in a small number of dimensi...
2005-01-01
In frame structures, consisting of columns and beams, gravity loading on beams (floors) leads to moments as well as axial forces in the columns. In cases with slender columns, maximum moments may develop between columns ends due to second order effects. Approximate methods for calculating maximum moments between column ends are given in Norwegian and international standards. These ``conventional'' methods are formulated in terms of approximate effective lengths and a moment gradient factor (o...
Taís Quevedo Marcolino
2014-01-01
The Clinical Reasoning Study supported by the American Occupational Therapy Association/AOTA and the American Occupational Therapy Foundation/AOTF in the United States in the late 1980s, had inaugurated the scientific production in the field and offered an initial framework on clinical reasoning for understanding and conducting clinical cases in Occupational Therapy. Most of the researches in this field have focused on reasoning processes, and point out the need to understand the contents of ...
Littlejohn, Clayton Mitchell
2016-01-01
Pritchard’s epistemological disjunctivist thinks that when we come to know things through vision our perceptual beliefs are based on reasons that provide factive support. The reasons that constitute the rational basis for your belief that the page before you is white and covered in black marks entails that it is and includes things that could not have provided rational support for your beliefs if you had been hallucinating. There are some issues that I would like to raise. First, what motivat...
CERN. Geneva
2015-01-01
Most physics results at the LHC end in a likelihood ratio test. This includes discovery and exclusion for searches as well as mass, cross-section, and coupling measurements. The use of Machine Learning (multivariate) algorithms in HEP is mainly restricted to searches, which can be reduced to classification between two fixed distributions: signal vs. background. I will show how we can extend the use of ML classifiers to distributions parameterized by physical quantities like masses and couplings as well as nuisance parameters associated to systematic uncertainties. This allows for one to approximate the likelihood ratio while still using a high dimensional feature vector for the data. Both the MEM and ABC approaches mentioned above aim to provide inference on model parameters (like cross-sections, masses, couplings, etc.). ABC is fundamentally tied Bayesian inference and focuses on the “likelihood free” setting where only a simulator is available and one cannot directly compute the likelihood for the dat...
Schmidt, Wolfgang M
1980-01-01
"In 1970, at the U. of Colorado, the author delivered a course of lectures on his famous generalization, then just established, relating to Roth's theorem on rational approxi- mations to algebraic numbers. The present volume is an ex- panded and up-dated version of the original mimeographed notes on the course. As an introduction to the author's own remarkable achievements relating to the Thue-Siegel-Roth theory, the text can hardly be bettered and the tract can already be regarded as a classic in its field."(Bull.LMS) "Schmidt's work on approximations by algebraic numbers belongs to the deepest and most satisfactory parts of number theory. These notes give the best accessible way to learn the subject. ... this book is highly recommended." (Mededelingen van het Wiskundig Genootschap)
Directory of Open Access Journals (Sweden)
Eriksson Charli
2009-12-01
Full Text Available Abstract Background Alcohol consumption among adolescents is a serious public health concern. Research has shown that prevention programs targeting parents can help prevent underage drinking. The problem is that parental participation in these kinds of interventions is generally low. Therefore, the aim of the present study is to examine non-participation in a parental support program aiming to prevent underage alcohol drinking. The Health Belief Model has been used as a tool for the analysis. Methods To understand non-participation in a parental program a quasi-experimental mixed-method design was used. The participants in the study were invited to participate in a parental program targeting parents with children in school years 7-9. A questionnaire was sent home to the parents before the program started. Two follow-up surveys were also carried out. The inclusion criteria for the study were that the parents had answered the questionnaire in school year 7 and either of the questionnaires in the two subsequent school years (n = 455. Multinomial logistic regression analysis was used to examine reasons for non-participation. The final follow-up questionnaire included an opened-ended question about reasons for non-participation. A qualitative content analysis was carried out and the two largest categories were included in the third model of the multinomial logistic regression analysis. Results Educational level was the most important socio-demographic factor for predicting non-participation. Parents with a lower level of education were less likely to participate than those who were more educated. Factors associated with adolescents and alcohol did not seem to be of significant importance. Instead, program-related factors predicted non-participation, e.g. parents who did not perceive any need for the intervention and who did not attend the information meeting were more likely to be non-participants. Practical issues, like time demands, also seemed to
Sparse approximation with bases
2015-01-01
This book systematically presents recent fundamental results on greedy approximation with respect to bases. Motivated by numerous applications, the last decade has seen great successes in studying nonlinear sparse approximation. Recent findings have established that greedy-type algorithms are suitable methods of nonlinear approximation in both sparse approximation with respect to bases and sparse approximation with respect to redundant systems. These insights, combined with some previous fundamental results, form the basis for constructing the theory of greedy approximation. Taking into account the theoretical and practical demand for this kind of theory, the book systematically elaborates a theoretical framework for greedy approximation and its applications. The book addresses the needs of researchers working in numerical mathematics, harmonic analysis, and functional analysis. It quickly takes the reader from classical results to the latest frontier, but is written at the level of a graduate course and do...
Directory of Open Access Journals (Sweden)
Cristinel Mortici
2015-01-01
Full Text Available In this survey we present our recent results on analysis of gamma function and related functions. The results obtained are in the theory of asymptotic analysis, approximation of gamma and polygamma functions, or in the theory of completely monotonic functions. The motivation of this first part is the work of C. Mortici [Product Approximations via Asymptotic Integration Amer. Math. Monthly 117 (2010 434-441] where a simple strategy for constructing asymptotic series is presented. The classical asymptotic series associated to Stirling, Wallis, Glaisher-Kinkelin are rediscovered. In the second section we discuss some new inequalities related to Landau constants and we establish some asymptotic formulas.
International Nuclear Information System (INIS)
Approximate formulas for determining the frequency and Q-factor of the complex conjugate roots, as well as the frequency of the real root, of the cubic equation for the case where the frequency of the complex-conjugate roots is close to the frequency of the real root have been presented in this work
Yin, George; Wang, Le Yi; Zhang, Hongwei
2014-12-01
Stochastic approximation methods have found extensive and diversified applications. Recent emergence of networked systems and cyber-physical systems has generated renewed interest in advancing stochastic approximation into a general framework to support algorithm development for information processing and decisions in such systems. This paper presents a survey on some recent developments in stochastic approximation methods and their applications. Using connected vehicles in platoon formation and coordination as a platform, we highlight some traditional and new methodologies of stochastic approximation algorithms and explain how they can be used to capture essential features in networked systems. Distinct features of networked systems with randomly switching topologies, dynamically evolving parameters, and unknown delays are presented, and control strategies are provided.
Sarwar, S.; Rashidi, M. M.
2016-07-01
This paper deals with the investigation of the analytical approximate solutions for two-term fractional-order diffusion, wave-diffusion, and telegraph equations. The fractional derivatives are defined in the Caputo sense, whose orders belong to the intervals [0,1], (1,2), and [1,2], respectively. In this paper, we extended optimal homotopy asymptotic method (OHAM) for two-term fractional-order wave-diffusion equations. Highly approximate solution is obtained in series form using this extended method. Approximate solution obtained by OHAM is compared with the exact solution. It is observed that OHAM is a prevailing and convergent method for the solutions of nonlinear-fractional-order time-dependent partial differential problems. The numerical results rendering that the applied method is explicit, effective, and easy to use, for handling more general fractional-order wave diffusion, diffusion, and telegraph problems.
Energy Technology Data Exchange (ETDEWEB)
Rogers, J.; Porter, K.
2012-03-01
This paper updates previous work that describes time period-based and other approximation methods for estimating the capacity value of wind power and extends it to include solar power. The paper summarizes various methods presented in utility integrated resource plans, regional transmission organization methodologies, regional stakeholder initiatives, regulatory proceedings, and academic and industry studies. Time period-based approximation methods typically measure the contribution of a wind or solar plant at the time of system peak - sometimes over a period of months or the average of multiple years.
DEFF Research Database (Denmark)
Dole, Shelley; Hilton, Annette; Hilton, Geoff;
2015-01-01
Proportional reasoning is widely acknowledged as a key to success in school mathematics, yet students’ continual difficulties with proportion-related tasks are well documented. This paper draws on a large research study that aimed to support 4th to 9th grade teachers to design and implement tasks...
FAYEZ MOUSTAFA MOAWAD, RAGAB
2016-01-01
[EN] The neutron diffusion equation is an approximation of the neutron transport equation that describes the neutron population in a nuclear reactor core. In particular, we will consider here VVER-type reactors which use the neutron diffusion equation discretized on hexagonal meshes. Most of the simulation codes of a nuclear power reactor use the multigroup neutron diffusion equation to describe the neutron distribution inside the reactor core.To study the stationary state of a reactor, the r...
Dual Control for Approximate Bayesian Reinforcement Learning
Klenske, Edgar D.; Hennig, Philipp
2015-01-01
Control of non-episodic, finite-horizon dynamical systems with uncertain dynamics poses a tough and elementary case of the exploration-exploitation trade-off. Bayesian reinforcement learning, reasoning about the effect of actions and future observations, offers a principled solution, but is intractable. We review, then extend an old approximate approach from control theory---where the problem is known as dual control---in the context of modern regression methods, specifically generalized line...
Two Major Types of Reasons in Common Law Method%普通法中的两类主要推理依据
Institute of Scientific and Technical Information of China (English)
贾海龙
2011-01-01
普通法方法中为了回答法律问题,要使用到多种推理依据,其中最重要的两种依据是形式性依据和实质性依据。形式性依据是具有权威形式的推理依据,典型代表为制定法和案例,还包括学者的论述、评论、法律汇编、重述等内容。其中有法律拘束力的制定法和案例是最有力的形式性依据。实质性依据不具有权威形式,而是凭借其内容的内在逻辑而获得说服力的推理依据,主要包括道德依据和政策目标依据两大类。普通法法官推理中,形式性依据的重要性是首位的,实质性依据起到辅助的作用,只有存在法律不周全的情况下,实质性依据才能成为首要推理依据。%In order to answer legal questions,the common law method employs a number of different types of reasons,among which formal reasons and substantive reasons are the two major types.Formal reasons are reasons with authoritative forms,including statutes and precedents and other authorities which are not sources of law.Substantive reasons are reasons without authoritative forms,including moral reasons and policy reasons.In common law reasoning,formal reasons are most important,while substantive reasons are of assistance.Only when there is deficiency in positive law can substantive reasons take a more important responsibility.
DEFF Research Database (Denmark)
Ditlevsen, Susanne; Samson, Adeline
2014-01-01
, but biophysical realistic models have to include the unobserved dynamics of ion channels. One such model is the stochastic Morris–Lecar model, defined by a nonlinear two-dimensional stochastic differential equation. The coordinates are coupled, that is, the unobserved coordinate is nonautonomous, the model...... of the Expectation–Maximization algorithm. It turns out that even the rate scaling parameter governing the opening and closing of ion channels of the unobserved coordinate can be reasonably estimated. An experimental data set of intracellular recordings of the membrane potential of a spinal motoneuron of a red......Parameter estimation in multidimensional diffusion models with only one coordinate observed is highly relevant in many biological applications, but a statistically difficult problem. In neuroscience, the membrane potential evolution in single neurons can be measured at high frequency...
DEFF Research Database (Denmark)
Tylén, Kristian; Fusaroli, Riccardo; Stege Bjørndahl, Johanne;
2015-01-01
Many types of everyday and specialized reasoning depend on diagrams: we use maps to find our way, we draw graphs and sketches to communicate concepts and prove geometrical theorems, and we manipulate diagrams to explore new creative solutions to problems. The active involvement and manipulation...... are manipulated in order to profile known information in an optimal fashion. At other times diagrams are explored in order to gain new insights, solve problems or discover hidden meaning potentials. The latter cases often entail manipulations that either generate additional information or extract information...
Chartier, Daniel
1996-01-01
Exposes two groups of adults in vocational-education training programs to two different programs (Logo-Educability exercises and Logical Reasoning Workshops) designed to improve their cognitive skills. Argues that low improvement scores for both groups demonstrate the inefficacy of the programs in helping students transfer learned cognitive skills…
A B-Spline-Based Colocation Method to Approximate the Solutions to the Equations of Fluid Dynamics
Energy Technology Data Exchange (ETDEWEB)
Johnson, Richard Wayne; Landon, Mark Dee
1999-07-01
The potential of a B-spline collocation method for numerically solving the equations of fluid dynamics is discussed. It is known that B-splines can resolve curves with drastically fewer data than can their standard shape function counterparts. This feature promises to allow much faster numerical simulations of fluid flow than standard finite volume/finite element methods without sacrificing accuracy. An example channel flow problem is solved using the method.
A B-Spline-Based Colocation Method to Approximate the Solutions to the Equations of Fluid Dynamics
Energy Technology Data Exchange (ETDEWEB)
M. D. Landon; R. W. Johnson
1999-07-01
The potential of a B-spline collocation method for numerically solving the equations of fluid dynamics is discussed. It is known that B-splines can resolve complex curves with drastically fewer data than can their standard shape function counterparts. This feature promises to allow much faster numerical simulations of fluid flow than standard finite volume/finite element methods without sacrificing accuracy. An example channel flow problem is solved using the method.
Ordered cones and approximation
Keimel, Klaus
1992-01-01
This book presents a unified approach to Korovkin-type approximation theorems. It includes classical material on the approximation of real-valuedfunctions as well as recent and new results on set-valued functions and stochastic processes, and on weighted approximation. The results are notonly of qualitative nature, but include quantitative bounds on the order of approximation. The book is addressed to researchers in functional analysis and approximation theory as well as to those that want to applythese methods in other fields. It is largely self- contained, but the readershould have a solid background in abstract functional analysis. The unified approach is based on a new notion of locally convex ordered cones that are not embeddable in vector spaces but allow Hahn-Banach type separation and extension theorems. This concept seems to be of independent interest.
Approximate Modified Policy Iteration
Scherrer, Bruno; Ghavamzadeh, Mohammad; Geist, Matthieu
2012-01-01
Modified policy iteration (MPI) is a dynamic programming (DP) algorithm that contains the two celebrated policy and value iteration methods. Despite its generality, MPI has not been thoroughly studied, especially its approximation form which is used when the state and/or action spaces are large or infinite. In this paper, we propose three approximate MPI (AMPI) algorithms that are extensions of the well-known approximate DP algorithms: fitted-value iteration, fitted-Q iteration, and classification-based policy iteration. We provide an error propagation analysis for AMPI that unifies those for approximate policy and value iteration. We also provide a finite-sample analysis for the classification-based implementation of AMPI (CBMPI), which is more general (and somehow contains) than the analysis of the other presented AMPI algorithms. An interesting observation is that the MPI's parameter allows us to control the balance of errors (in value function approximation and in estimating the greedy policy) in the fina...
Energy Technology Data Exchange (ETDEWEB)
Belendez, A. [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es; Pascual, C.; Gallego, S.; Ortuno, M.; Neipp, C. [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)
2007-11-26
A modified He's homotopy perturbation method (HHPM) is used to calculate the periodic solutions of a conservative nonlinear oscillator for which the elastic force term is proportional to x{sup 1/3}. The He's homotopy perturbation method is modified by truncating the infinite series corresponding to the first-order approximate solution before introducing this solution in the second-order linear differential equation, and so on. We find this modified HHPM works very well for the whole range of initial amplitudes, and the excellent agreement of the approximate frequencies and periodic solutions with the exact ones has been demonstrated and discussed. Only one iteration leads to high accuracy of the solutions with a maximal relative error for the approximate frequency of less than 0.6% for small and large values of oscillation amplitude, while this relative error is 0.17% for the second iteration and as low as 0.024% when the third approximation is considered. Comparison of the result obtained using this method with those obtained by different harmonic balance methods reveals that the former is very effective and convenient.
CranSLIK v1.0: stochastic prediction of oil spill transport and fate using approximation methods
Snow, B. J.; Moulitsas, I.; Kolios, A. J.; De Dominicis, M.
2014-07-01
This paper investigates the development of a model, called CranSLIK, to predict the transport and transformations of a point mass oil spill via a stochastic approach. Initially the various effects on destination are considered and key parameters are chosen which are expected to dominate the displacement. The variables considered are: wind velocity, surface water velocity, spill size, and spill age. For a point mass oil spill, it is found that the centre of mass can be determined by the wind and current data only, and the spill size and age can then be used to reconstruct the surface of the spill. These variables are sampled and simulations are performed using an open-source Lagrangian approach-based code, MEDSLIK II. Regression modelling is applied to create two sets of polynomials: one for the centre of mass, and one for the spill size. Simulations performed for a real oil spill case show that a minimum of approximately 80% of the oil is captured by CranSLIK. Finally, Monte Carlo simulation is implemented to allow for consideration of the most likely destination for the oil spill, when the distributions for the oceanographic conditions are known.
CranSLIK v1.0: stochastic prediction of oil spill transport and fate using approximation methods
Directory of Open Access Journals (Sweden)
B. J. Snow
2014-07-01
Full Text Available This paper investigates the development of a model, called CranSLIK, to predict the transport and transformations of a point mass oil spill via a stochastic approach. Initially the various effects on destination are considered and key parameters are chosen which are expected to dominate the displacement. The variables considered are: wind velocity, surface water velocity, spill size, and spill age. For a point mass oil spill, it is found that the centre of mass can be determined by the wind and current data only, and the spill size and age can then be used to reconstruct the surface of the spill. These variables are sampled and simulations are performed using an open-source Lagrangian approach-based code, MEDSLIK II. Regression modelling is applied to create two sets of polynomials: one for the centre of mass, and one for the spill size. Simulations performed for a real oil spill case show that a minimum of approximately 80% of the oil is captured by CranSLIK. Finally, Monte Carlo simulation is implemented to allow for consideration of the most likely destination for the oil spill, when the distributions for the oceanographic conditions are known.
International Nuclear Information System (INIS)
We theoretically discuss the magnetic-field-angle dependence of the zero-energy density of states (ZEDOS) in superconductors. Point-node and line-node superconducting gaps on spherical and cylindrical Fermi surfaces are considered. The Doppler-shift (DS) method and the Kramer-Pesch approximation (KPA) are used to calculate the ZEDOS. Numerical results show that consequences of the DS method are corrected by the KPA.
用同伦摄动法解Kdv-Burgers方程%Homotopy Perturbation Method and Approximate Solutions of Kdv-Burgers Equaition
Institute of Scientific and Technical Information of China (English)
李阳; 王佩臣
2011-01-01
利用行波变换将Kdv-Burgers方程化为常微分方程,并结合同伦摄动方法求它的二阶近似解.%Some discussion and gets to some conclusion are made on how to transform Kdv-Burgers equation into the ordinary differential equation with traveling wave transform method and homotopy perturbation method.And get the equations of second order approximate solutions.
Directory of Open Access Journals (Sweden)
Span Georgeta Ancuta
2012-07-01
Full Text Available The study shows the reasons taken into account by the students in choosing an academic preparation. Free courses and employment opportunities during or after graduation are the most important advantages students expect to receive from an educational program that aims to follow. The empirical section results emphasize the efficiency and performance of the master program financed by the European Social Fund. \\\\\\\\r\\\\\\\
Ahlkrona, Josefin; Lötstedt, Per; Kirchner, Nina; Zwinger, Thomas
2016-03-01
We propose and implement a new method, called the Ice Sheet Coupled Approximation Levels (ISCAL) method, for simulation of ice sheet flow in large domains during long time-intervals. The method couples the full Stokes (FS) equations with the Shallow Ice Approximation (SIA). The part of the domain where SIA is applied is determined automatically and dynamically based on estimates of the modeling error. For a three dimensional model problem, ISCAL computes the solution substantially faster with a low reduction in accuracy compared to a monolithic FS. Furthermore, ISCAL is shown to be able to detect rapid dynamic changes in the flow. Three different error estimations are applied and compared. Finally, ISCAL is applied to the Greenland Ice Sheet on a quasi-uniform grid, proving ISCAL to be a potential valuable tool for the ice sheet modeling community.
Directory of Open Access Journals (Sweden)
Chi-Chang Wang
2013-09-01
Full Text Available This paper seeks to use the proposed residual correction method in coordination with the monotone iterative technique to obtain upper and lower approximate solutions of singularly perturbed non-linear boundary value problems. First, the monotonicity of a non-linear differential equation is reinforced using the monotone iterative technique, then the cubic-spline method is applied to discretize and convert the differential equation into the mathematical programming problems of an inequation, and finally based on the residual correction concept, complex constraint solution problems are transformed into simpler questions of equational iteration. As verified by the four examples given in this paper, the method proposed hereof can be utilized to fast obtain the upper and lower solutions of questions of this kind, and to easily identify the error range between mean approximate solutions and exact solutions.
Ahlkrona, Josefin; Kirchner, Nina; Zwinger, Thomas
2015-01-01
We propose and implement a new method, called the Ice Sheet Coupled Approximation Levels (ISCAL) method, for simulation of ice sheet flow in large domains under long time-intervals. The method couples the exact, full Stokes (FS) equations with the Shallow Ice Approximation (SIA). The part of the domain where SIA is applied is determined automatically and dynamically based on estimates of the modeling error. For a three dimensional model problem where the number of degrees of freedom is comparable to a real world application, ISCAL performs almost an order of magnitude faster with a low reduction in accuracy compared to a monolithic FS. Furthermore, ISCAL is shown to be able to detect rapid dynamic changes in the flow. Three different error estimations are applied and compared. Finally, ISCAL is applied to the Greenland Ice Sheet, proving ISCAL to be a potential valuable tool for the ice sheet modeling community.
Jordon, D. E.; Patterson, W.; Sandlin, D. R.
1985-01-01
The XV-15 Tilt Rotor Research Aircraft download phenomenon was analyzed. This phenomenon is a direct result of the two rotor wakes impinging on the wing upper surface when the aircraft is in the hover configuration. For this study the analysis proceeded along tow lines. First was a method whereby results from actual hover tests of the XV-15 aircraft were combined with drag coefficient results from wind tunnel tests of a wing that was representative of the aircraft wing. Second, an analytical method was used that modeled that airflow caused gy the two rotors. Formulas were developed in such a way that acomputer program could be used to calculate the axial velocities were then used in conjunction with the aforementioned wind tunnel drag coefficinet results to produce download values. An attempt was made to validate the analytical results by modeling a model rotor system for which direct download values were determinrd..
Lorin, E.; Yang, X.; Antoine, X.
2016-06-01
The paper is devoted to develop efficient domain decomposition methods for the linear Schrödinger equation beyond the semiclassical regime, which does not carry a small enough rescaled Planck constant for asymptotic methods (e.g. geometric optics) to produce a good accuracy, but which is too computationally expensive if direct methods (e.g. finite difference) are applied. This belongs to the category of computing middle-frequency wave propagation, where neither asymptotic nor direct methods can be directly used with both efficiency and accuracy. Motivated by recent works of the authors on absorbing boundary conditions (Antoine et al. (2014) [13] and Yang and Zhang (2014) [43]), we introduce Semiclassical Schwarz Waveform Relaxation methods (SSWR), which are seamless integrations of semiclassical approximation to Schwarz Waveform Relaxation methods. Two versions are proposed respectively based on Herman-Kluk propagation and geometric optics, and we prove the convergence and provide numerical evidence of efficiency and accuracy of these methods.
Xuan, Z C; Lassila, T. (Toni); Rozza, G; Quarteroni, A
2010-01-01
Verification of the computation of local quantities of interest, e.g. the displacements at a point, the stresses in a local area and the stress intensity factors at crack tips, plays an important role in improving the structural design for safety. In this paper, the smoothed finite element method (SFEM) is used for finding upper and lower bounds on the local quantities of interest that are outputs of the displacement field for linear elasticity problems, based on bounds on strain energy in bo...
Maria Ługowska; Zofia Rzymowska
2014-01-01
The work presents the results of a study on the biodiversity of agrocenoses using ecological indices. In order to calculate the measures, phytosociological relevés were made and exact methods were applied in winter cereals, spring cereals, tuber crops and stubble fields. The objective of the work was to compare ecological indices (Simpson’s index of dominance C, Simpson’s index of species richness D, and Shannon-Wiener index of biodiversity H’) calculated using the number of plants and their ...
Indian Academy of Sciences (India)
KAUSHIK MAJI
2016-08-01
We propose a variant of the multiconfiguration time-dependent Hartree (MCTDH) method within the framework of Hermite-distributed approximating functional (HDAF) method. The discretized Hamiltonian is a highly banded Toeplitz matrix which significantly reduces computational cost in terms of both storage and number of operations. The method proposed is employed to carry out the study of tunnelling dynamics of two coupled double well oscillators. We have calculated the orthogonality time \\tau , which is a measure of the time interval for an initial state to evolve into its orthogonal state. It is observed that the coupling has a significant effect on \\tau .
Vitanov, Nikolay K.
2011-03-01
We discuss the class of equations ∑i,j=0mAij(u){∂iu}/{∂ti}∂+∑k,l=0nBkl(u){∂ku}/{∂xk}∂=C(u) where Aij( u), Bkl( u) and C( u) are functions of u( x, t) as follows: (i) Aij, Bkl and C are polynomials of u; or (ii) Aij, Bkl and C can be reduced to polynomials of u by means of Taylor series for small values of u. For these two cases the above-mentioned class of equations consists of nonlinear PDEs with polynomial nonlinearities. We show that the modified method of simplest equation is powerful tool for obtaining exact traveling-wave solution of this class of equations. The balance equations for the sub-class of traveling-wave solutions of the investigated class of equations are obtained. We illustrate the method by obtaining exact traveling-wave solutions (i) of the Swift-Hohenberg equation and (ii) of the generalized Rayleigh equation for the cases when the extended tanh-equation or the equations of Bernoulli and Riccati are used as simplest equations.
Approximation by planar elastic curves
DEFF Research Database (Denmark)
Brander, David; Gravesen, Jens; Nørbjerg, Toke Bjerge
2015-01-01
We give an algorithm for approximating a given plane curve segment by a planar elastic curve. The method depends on an analytic representation of the space of elastic curve segments, together with a geometric method for obtaining a good initial guess for the approximating curve. A gradient......-driven optimization is then used to find the approximating elastic curve....
DEFF Research Database (Denmark)
Senjean, Bruno; Knecht, Stefan; Jensen, Hans Jørgen Aa;
2015-01-01
equiensembles. It is shown that such a linear interpolation method (LIM) can be rationalized and that it effectively introduces weight dependence effects. As proof of principle, the LIM has been applied to He, Be, and H2 in both equilibrium and stretched geometries as well as the stretched HeH+ molecule. Very......Gross-Oliveira-Kohn density-functional theory (GOK-DFT) for ensembles is, in principle, very attractive but has been hard to use in practice. A practical model based on GOK-DFT for the calculation of electronic excitation energies is discussed. The model relies on two modifications of GOK-DFT: use......, which complements the long-range wave-function-based ensemble energy contribution, should vary with the ensemble weights even when the density is held fixed. This weight dependence ensures that the range-separated ensemble energy varies linearly with the ensemble weights. When the (weight...
Bousserez, Nicolas
2016-01-01
This paper provides a detailed theoretical analysis of methods to approximate the solutions of high-dimensional (>10^6) linear Bayesian problems. An optimal low-rank projection that maximizes the information content of the Bayesian inversion is proposed and efficiently constructed using a scalable randomized SVD algorithm. Useful optimality results are established for the associated posterior error covariance matrix and posterior mean approximations, which are further investigated in a numerical experiment consisting of a large-scale atmospheric tracer transport source-inversion problem. This method proves to be a robust and efficient approach to dimension reduction, as well as a natural framework to analyze the information content of the inversion. Possible extensions of this approach to the non-linear framework in the context of operational numerical weather forecast data assimilation systems based on the incremental 4D-Var technique are also discussed, and a detailed implementation of a new Randomized Incr...
On negative binomial approximation to k-runs
Wang, Xiaoxin; Xia, Aihua
2008-01-01
The distributions of the run occurrences for a sequence of independent and identically distributed (i.i.d.) experiments are usually obtained by combinatorial methods (see Balakrishnan and Koutras (2002, Chapter 5)) and the resulting formulae are often very tedious, while the distributions for non i.i.d. experiments are generally intractable. It is therefore of practical interest to find a suitable approximate model with reasonable approximation accuracy. In this paper we ...
一种集成式不确定推理方法研究%Research on an Ensemble Method of Uncertainty Reasoning
Institute of Scientific and Technical Information of China (English)
贺怀清; 李建伏
2011-01-01
Ensemble learning is a machine learning paradigm where multiple models are strategically generated and combined to obtain better predictive performance than a single learning method.It was proven that ensemble learning is feasible and tends to yield better results.Uncertainty reasoning is one of the important directions in artificial intelligence.Various uncertainty reasoning methods have been developed and all have their own advantages and disadvantages.Motivated by ensemble learning, an ensemble method of uncertainty reasoning was proposed.The main idea of the new method is in accordance with the basic framework of ensemble learning,where multiple uncertainty reasoning methods is used in time and the result of various reasoning methods is integrated by some rules as the final result.Finally, theoretical analysis and experimental tests show that the ensemble uncertainty reasoning method is effective and feasible.%集成学习是采用某种规则把一系列学习器的结果进行整合以获得比单个学习器更好的学习效果的一种机器学习方法.研究表明集成学习是可行的,能取得比传统学习方法更好的性能.不确定推理是人工智能的重要研究方向之一,目前已经开发出了多种不确定推理方法,这些方法在实际应用中各有优缺点.借鉴集成学习,提出一种集成式不确定推理方法,其基本思想是按照一定的策略集成多种不确定推理方法,以提高推理的准确性.理论分析和实验结果验证了方法的合理性和可行性.
Institute of Scientific and Technical Information of China (English)
2007-01-01
In this paper, we are concerned with the partial regularity for the weak solutions of energy minimizing p-harmonic maps under the controllable growth condition. We get the interior partial regularity by the p-harmonic approximation method together with the technique used to get the decay estimation on some Degenerate elliptic equations and the obstacle problem by Tan and Yan. In particular, we directly get the optimal regularity.
Motorin, A. A.; Stupitsky, E. L.; Kholodov, A. S.
2016-07-01
The spatiotemporal pattern for the development of a plasma cloud formed in the ionosphere and the main cloud gas-dynamic characteristics have been obtained from 3D calculations of the explosion-type plasmodynamic flows previously performed by us. An approximate method for estimating the plasma temperature and ionization degree with the introduction of the effective adiabatic index has been proposed based on these results.
Moraes Rêgo, Patrícia Helena; Viana da Fonseca Neto, João; Ferreira, Ernesto M.
2015-08-01
The main focus of this article is to present a proposal to solve, via UDUT factorisation, the convergence and numerical stability problems that are related to the covariance matrix ill-conditioning of the recursive least squares (RLS) approach for online approximations of the algebraic Riccati equation (ARE) solution associated with the discrete linear quadratic regulator (DLQR) problem formulated in the actor-critic reinforcement learning and approximate dynamic programming context. The parameterisations of the Bellman equation, utility function and dynamic system as well as the algebra of Kronecker product assemble a framework for the solution of the DLQR problem. The condition number and the positivity parameter of the covariance matrix are associated with statistical metrics for evaluating the approximation performance of the ARE solution via RLS-based estimators. The performance of RLS approximators is also evaluated in terms of consistence and polarisation when associated with reinforcement learning methods. The used methodology contemplates realisations of online designs for DLQR controllers that is evaluated in a multivariable dynamic system model.
Chatterjee, Koushik; Pastorczak, Ewa; Jawulski, Konrad; Pernal, Katarzyna
2016-06-01
A perfect-pairing generalized valence bond (GVB) approximation is known to be one of the simplest approximations, which allows one to capture the essence of static correlation in molecular systems. In spite of its attractive feature of being relatively computationally efficient, this approximation misses a large portion of dynamic correlation and does not offer sufficient accuracy to be generally useful for studying electronic structure of molecules. We propose to correct the GVB model and alleviate some of its deficiencies by amending it with the correlation energy correction derived from the recently formulated extended random phase approximation (ERPA). On the examples of systems of diverse electronic structures, we show that the resulting ERPA-GVB method greatly improves upon the GVB model. ERPA-GVB recovers most of the electron correlation and it yields energy barrier heights of excellent accuracy. Thanks to a balanced treatment of static and dynamic correlation, ERPA-GVB stays reliable when one moves from systems dominated by dynamic electron correlation to those for which the static correlation comes into play.
DEFF Research Database (Denmark)
Jeong, Cheol-Ho; Ih, Jeong-Guon; Rindel, Jens Holger
2008-01-01
surface and the complex wave number for describing the propagation characteristics. In this study, two types of approximate real reflection coefficients derived from the measured absorption coefficient were tested for a practical applicability. As a test example, pressure impulse responses and energy......The phased beam tracing method (PBTM) was suggested as a medium-frequency simulation technique for the calculation of impulse response, although main assumptions of geometric acoustics still hold. The phased method needs the reflection coefficient for characterizing the acoustic property of a...
Directory of Open Access Journals (Sweden)
K. V. Dobrego
2015-01-01
Full Text Available Differential approximation is derived from radiation transfer equation by averaging over the solid angle. It is one of the more effective methods for engineering calculations of radia- tive heat transfer in complex three-dimensional thermal power systems with selective and scattering media. The new method for improvement of accuracy of the differential approximation based on using of auto-adaptable boundary conditions is introduced in the paper. The efficiency of the named method is proved for the test 2D-systems. Self-consistent auto-adaptable boundary conditions taking into consideration the nonorthogonal component of the incident to the boundary radiation flux are formulated. It is demonstrated that taking in- to consideration of the non- orthogonal incident flux in multi-dimensional systems, such as furnaces, boilers, combustion chambers improves the accuracy of the radiant flux simulations and to more extend in the zones adjacent to the edges of the chamber.Test simulations utilizing the differential approximation method with traditional boundary conditions, new self-consistent boundary conditions and “precise” discrete ordinates method were performed. The mean square errors of the resulting radiative fluxes calculated along the boundary of rectangular and triangular test areas were decreased 1.5–2 times by using auto- adaptable boundary conditions. Radiation flux gaps in the corner points of non-symmetric sys- tems are revealed by using auto-adaptable boundary conditions which can not be obtained by using the conventional boundary conditions.
Software Architecture Design Reasoning
Tang, Antony; van Vliet, Hans
Despite recent advancements in software architecture knowledge management and design rationale modeling, industrial practice is behind in adopting these methods. The lack of empirical proofs and the lack of a practical process that can be easily incorporated by practitioners are some of the hindrance for adoptions. In particular, the process to support systematic design reasoning is not available. To rectify this issue, we propose a design reasoning process to help architects cope with an architectural design environment where design concerns are cross-cutting and diversified.We use an industrial case study to validate that the design reasoning process can help improve the quality of software architecture design. The results have indicated that associating design concerns and identifying design options are important steps in design reasoning.
26 CFR 1.412(c)(2)-1 - Valuation of plan assets; reasonable actuarial valuation methods.
2010-04-01
...) produce a “smoothing” effect. Thus, investment performance, including appreciation or depreciation in the... including appreciation and depreciation experienced by the plan during that period. However, the method... year, in addition to any subsequent reports. (4) Effect of change of asset valuation method. A...
Directory of Open Access Journals (Sweden)
Didier COURBET
2013-07-01
Full Text Available If multidisciplinarity is necessary, first, for studying the widest possible set of communication phenomena (organizational, in groups, interpersonal, media, computer-mediated communication... and, secondly, for grasping the complexity of the different moments of the same phenomenon of communication (production, content, reception, circulation ..., methodological pluralism is also important. However, French research in communication sciences leaves in the shade a number of phenomena and moments of communication that could be better understood thanks to the experimental method. We will underline that the epistemological issues related to rational use of the experimental method in communication sciences are not negligible: it allows the study of objects that cannot be investigated with other methods and offers the opportunity to build knowledge by the refutation of hypotheses and theoretical propositions. We will clarify some epistemological misunderstandings concerning this method. First, it is actually a method of studying complex systems and communication processes. Secondly, its use is not incompatible with constructivism.
Directory of Open Access Journals (Sweden)
Lin Shao
2016-01-01
Full Text Available Due to large numbers of antennas and users, matrix inversion is complicated in linear precoding techniques for massive MIMO systems. Several approximated matrix inversion methods, including the Neumann series, have been proposed to reduce the complexity. However, the Neumann series does not converge fast enough. In this paper, to speed up convergence, a new joint Newton iteration and Neumann series method is proposed, with the first iteration result of Newton iteration method being employed to reconstruct the Neumann series. Then, a high probability convergence condition is established, which can offer useful guidelines for practical massive MIMO systems. Finally, simulation examples are given to demonstrate that the new joint Newton iteration and Neumann series method has a faster convergence rate compared to the previous Neumann series, with almost no increase in complexity when the iteration number is greater than or equal to 2.
Mistry, Rashmita S; White, Elizabeth S; Chow, Kirby A; Griffin, Katherine M; Nenadal, Lindsey
2016-01-01
Mixed methods research approaches are gaining traction across various social science disciplines, including among developmental scientists. In this chapter, we discuss the utility of a mixed methods research approach in examining issues related to equity and justice. We incorporate a brief overview of quantitative and qualitative monomethod research approaches in our larger discussion of the advantages, procedures, and considerations of employing a mixed methods design to advance developmental science from an equity and justice perspective. To better illustrate the theoretical and practical significance of a mixed methods research approach, we include examples of research conducted on children and adolescents' conceptions of economic inequality as one example of developmental science research with an equity and justice frame.
Diophantine approximations on fractals
Einsiedler, Manfred; Shapira, Uri
2009-01-01
We exploit dynamical properties of diagonal actions to derive results in Diophantine approximations. In particular, we prove that the continued fraction expansion of almost any point on the middle third Cantor set (with respect to the natural measure) contains all finite patterns (hence is well approximable). Similarly, we show that for a variety of fractals in [0,1]^2, possessing some symmetry, almost any point is not Dirichlet improvable (hence is well approximable) and has property C (after Cassels). We then settle by similar methods a conjecture of M. Boshernitzan saying that there are no irrational numbers x in the unit interval such that the continued fraction expansions of {nx mod1 : n is a natural number} are uniformly eventually bounded.
Thorn, Graeme J; King, John R
2016-01-01
The Gram-positive bacterium Clostridium acetobutylicum is an anaerobic endospore-forming species which produces acetone, butanol and ethanol via the acetone-butanol (AB) fermentation process, leading to biofuels including butanol. In previous work we looked to estimate the parameters in an ordinary differential equation model of the glucose metabolism network using data from pH-controlled continuous culture experiments. Here we combine two approaches, namely the approximate Bayesian computation via an existing sequential Monte Carlo (ABC-SMC) method (to compute credible intervals for the parameters), and the profile likelihood estimation (PLE) (to improve the calculation of confidence intervals for the same parameters), the parameters in both cases being derived from experimental data from forward shift experiments. We also apply the ABC-SMC method to investigate which of the models introduced previously (one non-sporulation and four sporulation models) have the greatest strength of evidence. We find that the joint approximate posterior distribution of the parameters determines the same parameters as previously, including all of the basal and increased enzyme production rates and enzyme reaction activity parameters, as well as the Michaelis-Menten kinetic parameters for glucose ingestion, while other parameters are not as well-determined, particularly those connected with the internal metabolites acetyl-CoA, acetoacetyl-CoA and butyryl-CoA. We also find that the approximate posterior is strongly non-Gaussian, indicating that our previous assumption of elliptical contours of the distribution is not valid, which has the effect of reducing the numbers of pairs of parameters that are (linearly) correlated with each other. Calculations of confidence intervals using the PLE method back this up. Finally, we find that all five of our models are equally likely, given the data available at present. PMID:26561777
Shargatov, V. A.; Gubin, S. A.; Okunev, D. Yu
2015-11-01
Based on the assumption of the existence of the partial chemical equilibrium in the detonation products, an approximate method for calculating composition of the detonation products is developed. The method uses the assumption of the existence of extremum of Helmholtz free energy for a given density, temperature, and molecular weight of the detonation products mixture. Without significant loss of accuracy to the solution of stiff differential equations, detailed kinetic mechanism can be replaced by one differential equation and a system of algebraic equations. This method is always consistent with the detailed mechanism and can be used separately or in conjunction with the decision of a stiff system, replacing it when bimolecular reactions are near equilibrium.
Chacón Rebollo, Tomás
2015-03-01
This paper introduces a variational multi-scale method where the sub-grid scales are computed by spectral approximations. It is based upon an extension of the spectral theorem to non necessarily self-adjoint elliptic operators that have an associated base of eigenfunctions which are orthonormal in weighted L2 spaces. This allows to element-wise calculate the sub-grid scales by means of the associated spectral expansion. We propose a feasible VMS-spectral method by truncation of this spectral expansion to a finite number of modes. We apply this general framework to the convection-diffusion equation, by analytically computing the family of eigenfunctions. We perform a convergence and error analysis. We also present some numerical tests that show the stability of the method for an odd number of spectral modes, and an improvement of accuracy in the large resolved scales, due to the adding of the sub-grid spectral scales.
Hunter, Craig A.
1995-01-01
An analytical/numerical method has been developed to predict the static thrust performance of non-axisymmetric, two-dimensional convergent-divergent exhaust nozzles. Thermodynamic nozzle performance effects due to over- and underexpansion are modeled using one-dimensional compressible flow theory. Boundary layer development and skin friction losses are calculated using an approximate integral momentum method based on the classic karman-Polhausen solution. Angularity effects are included with these two models in a computational Nozzle Performance Analysis Code, NPAC. In four different case studies, results from NPAC are compared to experimental data obtained from subscale nozzle testing to demonstrate the capabilities and limitations of the NPAC method. In several cases, the NPAC prediction matched experimental gross thrust efficiency data to within 0.1 percent at a design NPR, and to within 0.5 percent at off-design conditions.
Energy Technology Data Exchange (ETDEWEB)
Seiler, C.
2001-07-01
This doctoral thesis presents approximative methods for the stability analysis of anchored liquid storage tanks under earthquake excitation. By first introducing a quasistatic model well known phenomena of collapse are analysed with little numerical effort and the underlying mechanisms of collapse are explained. Subsequently, a more detailed analysis of the structural behavior in the time domain is obtained by a complete interactive model and by employing a suitable time integration method. In this context, the dynamic stability behavior is calculated by defining a problem oriented criterion. Performing an extensive parameter study the approximative methods are discussed and the results lead to a new empirical design concept which may be implemented in the current draft of Eurocode 8, part 4 for stability verifications. (orig.) [German] In der vorliegenden Arbeit wird das Stabilitaetsverhalten von verankerten Fluessigkeitsbehaeltern unter seismischer Einwirkung mit Hilfe unterschiedlicher Naeherungsmethoden behandelt. Die Einfuehrung eines quasistatischen Ersatzmodells bietet zunaechst die Moeglichkeit, bekannte Versagensphaenomene mit geringem numerischen Aufwand zu berechnen und die zugrundeliegenden Versagensmechanismen zu erklaeren. Zu einer genaueren Analyse des Tragverhaltens im Zeitbereich wird anschliessend ein vollstaendiges Interaktionsmodell in Verbindung mit einem geeigneten Zeitintegrationsverfahren herangezogen. Das dynamische Stabilitaetsverhalten wird dabei mit einem Kriterium beurteilt, das problemorientiert definiert wird. Eine umfangreiche Parameterstudie stellt die vorgestellten Naeherungsverfahren gegenueber und dient als Datenbasis fuer ein neu entwickeltes empirisches Bemessungskonzept, das in die aktuelle Normengebung des EC 8, Teil 4 in bezug auf die erforderlichen Stabilitaetsnachweise aufgenommen werden koennte. (orig.)
Ribeiro, Apoena A; Purger, Flávia; Rodrigues, Jonas A; Oliveira, Patrícia R A; Lussi, Adrian; Monteiro, Antonio Henrique; Alves, Haimon D L; Assis, Joaquim T; Vasconcellos, Adalberto B
2015-01-01
This in vivo study aimed to evaluate the influence of contact points on the approximal caries detection in primary molars, by comparing the performance of the DIAGNOdent pen and visual-tactile examination after tooth separation to bitewing radiography (BW). A total of 112 children were examined and 33 children were selected. In three periods (a, b, and c), 209 approximal surfaces were examined: (a) examiner 1 performed visual-tactile examination using the Nyvad criteria (EX1); examiner 2 used DIAGNOdent pen (LF1) and took BW; (b) 1 week later, after tooth separation, examiner 1 performed the second visual-tactile examination (EX2) and examiner 2 used DIAGNOdent again (LF2); (c) after tooth exfoliation, surfaces were directly examined using DIAGNOdent (LF3). Teeth were examined by computed microtomography as a reference standard. Analyses were based on diagnostic thresholds: D1: D 0 = health, D 1 –D 4 = disease; D2: D 0 , D 1 = health, D 2 –D 4 = disease; D3: D 0 –D 2 = health, D 3 , D 4 = disease. At D1, the highest sensitivity/specificity were observed for EX1 (1.00)/LF3 (0.68), respectively. At D2, the highest sensitivity/ specificity were observed for LF3 (0.69)/BW (1.00), respectively. At D3, the highest sensitivity/specificity were observed for LF3 (0.78)/EX1, EX2 and BW (1.00). EX1 showed higher accuracy values than LF1, and EX2 showed similar values to LF2. We concluded that the visual-tactile examination showed better results in detecting sound surfaces and approximal caries lesions without tooth separation. However, the effectiveness of approximal caries lesion detection of both methods was increased by the absence of contact points. Therefore, regardless of the method of detection, orthodontic separating elastics should be used as a complementary tool for the diagnosis of approximal noncavitated lesions in primary molars.
Diophantine approximation and badly approximable sets
DEFF Research Database (Denmark)
Kristensen, S.; Thorn, R.; Velani, S.
2006-01-01
. The classical set Bad of `badly approximable' numbers in the theory of Diophantine approximation falls within our framework as do the sets Bad(i,j) of simultaneously badly approximable numbers. Under various natural conditions we prove that the badly approximable subsets of Omega have full Hausdorff dimension....... Applications of our general framework include those from number theory (classical, complex, p-adic and formal power series) and dynamical systems (iterated function schemes, rational maps and Kleinian groups)....
Scholte, Marijn; Neeleman-van der Steen, Catherina W. M.; van der Wees, Philip J.; Nijhuis-van der Sanden, Maria W. G.; Braspenning, Jozé
2016-01-01
Objectives To explain the use of feedback reports for quality improvements by the reasons to participate in quality measuring projects and to identify barriers and facilitators. Design Mixed methods design. Methods In 2009–2011 a national audit and feedback system for physical therapy (Qualiphy) was initiated in the Netherlands. After each data collection round, an evaluation survey was held amongst its participants. The evaluation survey data was used to explain the use of feedback reports by studying the reasons to participate with Qualiphy with correlation measures and logistic regression. Semi-structured interviews with PTs served to seek confirmation and disentangle barriers and facilitators. Results Analysis of 257 surveys (response rate: 42.8%) showed that therapists with only financial reasons were less likely to use feedback reports (OR = 0.24;95%CI = 0.11–0.52) compared to therapists with a mixture of reasons. PTs in 2009 and 2010 were more likely to use the feedback reports for quality improvement than PTs in 2011 (OR = 2.41;95%CI = 1.25–4.64 respectively OR = 3.28;95%CI = 1.51–7.10). Changing circumstances in 2011, i.e. using EHRs and financial incentives, had a negative effect on the use of feedback reports (OR = 0.40, 95%CI = 0.20–0.78). Interviews with 12 physical therapists showed that feedback reports could serve as a tool to support and structure quality improvement plans. Barriers were distrust and perceived self-reporting bias on indicator scores. Conclusions Implementing financial incentives that are not well-specified and well-targeted can have an adverse effect on using feedback reports to improve quality of care. Distrust is a major barrier to implementing quality systems. PMID:27518113
Finite elements and approximation
Zienkiewicz, O C
2006-01-01
A powerful tool for the approximate solution of differential equations, the finite element is extensively used in industry and research. This book offers students of engineering and physics a comprehensive view of the principles involved, with numerous illustrative examples and exercises.Starting with continuum boundary value problems and the need for numerical discretization, the text examines finite difference methods, weighted residual methods in the context of continuous trial functions, and piecewise defined trial functions and the finite element method. Additional topics include higher o
AN APPROXIMATE SOLUTION FOR THE EFFECTIVE ELASTIC MODULI OF DIFFERENTIAL METHOD%有效弹性模量微分法的一种近似解法
Institute of Scientific and Technical Information of China (English)
吴云章; 兑关锁; 朱玉萍
2011-01-01
鉴于Eshelby张量在整个微分法的"取出-添入"过程中的变化对等效模量变化影响较小,论文推出了微分法的近似显式解.该近似解形式简捷,计算方便,不仅适用于球形颗粒夹杂,对随机短纤维夹杂等情况也同样适应,所得结果与实验数据非常接近.%Considering that the effect of Eshelby's tensor in view of the entire differential method of ‘extraction-accession' during the process of change in modulus variation is less,an approximate explicit expression of the differential method is established in the paper. The simple form of approximate solution is facilitating to calculation. The expression can be fit very well for spherical inclusions and stochastic short fiber inclusions. It shows that the theoretical prediction results are in good agreement with the existed experimental data.
Liu, Rentao; Jiang, Jiping; Guo, Liang; Shi, Bin; Liu, Jie; Du, Zhaolin; Wang, Peng
2016-06-01
In-depth filtering of emergency disposal technology (EDT) and materials has been required in the process of environmental pollution emergency disposal. However, an urgent problem that must be solved is how to quickly and accurately select the most appropriate materials for treating a pollution event from the existing spill control and clean-up materials (SCCM). To meet this need, the following objectives were addressed in this study. First, the material base and a case base for environment pollution emergency disposal were established to build a foundation and provide material for SCCM screening. Second, the multiple case-based reasoning model method with a difference-driven revision strategy (DDRS-MCBR) was applied to improve the original dual case-based reasoning model method system, and screening and decision-making was performed for SCCM using this model. Third, an actual environmental pollution accident from 2012 was used as a case study to verify the material base, case base, and screening model. The results demonstrated that the DDRS-MCBR method was fast, efficient, and practical. The DDRS-MCBR method changes the passive situation in which the choice of SCCM screening depends only on the subjective experience of the decision maker and offers a new approach to screening SCCM.
An Approximate Model of Microchannel Cooling
Institute of Scientific and Technical Information of China (English)
ShipingYu; MingdaoXin
1994-01-01
Forced convective heat transfer in micro-rectangular channels can be described by a group of two-dimensional differential equations.These equations take the conduction in microchannel wall along the direction of flow of coolants into account,which are more generalized than those which neglect the conduction.For the same reason,they are suitable particularly for gases-cooled microchannels.With only numerical solution to the equations till today,an approximate analytic solution is derived here,From this solution,a rather simple formula can be introduced further,by which the differences between considering the conduction and neglecting it are easily found.In addition,the reasonableness of the classical fin method is also discussed.An experimental example of air-cooled microchannels is illustrated.
International Nuclear Information System (INIS)
Both the nomogram method and discrete point approximation can be used for estimation of doses resulting from gamma rays emitted by radionuclides in finite cloud. The former can only be applied for evaluation of dose from nine noble gas finite clouds in case of constant weather conditions, but the later can be used for estimation of doses from some radionuclides finite clouds is case of changing weather condition during the transport times. Some calculations using the two methods have been made under the described situation. The comparison computations for absorbed dose rate in air show a very good agreement. Mostly, above 86% of the computed data are within a factor of 2, up to 96% of data are within a factor of 3. Naturally, it should be noticed that the remaining percentage have an error up to a factor of 6 at stable atmospheric condition. (2 tabs.)
Reasonable attempt to no-mesh and the SF method; Nomesshu to SF koho de gorika ni torai
Energy Technology Data Exchange (ETDEWEB)
NONE
1999-08-10
In the Iwate Construction Work Office, the Ministry of Construction, the rational construction of concrete pavement was challenged to apply the characteristics of the slipforming paver. In the usual concrete pavement, there existed problems during construction to install molds and iron networks. In the pilot work of technology application conducted in the Route No4 and the Hiraizumi Bypass, a concrete plate with a thickness of 30cm without iron nets was directly paved on a lower layer subbase course of 15cm and an intermediate layer of 4cm by the slipforming pavement without mold construction. In the total extension of 5800m, no-mesh pavement was conducted in a limitation of about 1000m in which the subgrade was completed over ten years. It was an attempt to reduce the construction cost, manpower and the construction period and to improve the working environment (the provisional two traffic-lanes with the construction width of 4.5m + 3.8m). The volume of traffic in the Route No.4 was 21,000 automobiles per day and the high mix rate of the large automobiles even reached 18%. The director of the Komatsu branch offices said that the great social contribution was given if the durable concrete pavement could be rationally constructed. The pavement of shoulders and the L-shaped lateral groove has been conducted by the slipforming method. (translated by NEDO)
Exact constants in approximation theory
Korneichuk, N
1991-01-01
This book is intended as a self-contained introduction for non-specialists, or as a reference work for experts, to the particular area of approximation theory that is concerned with exact constants. The results apply mainly to extremal problems in approximation theory, which in turn are closely related to numerical analysis and optimization. The book encompasses a wide range of questions and problems: best approximation by polynomials and splines; linear approximation methods, such as spline-approximation; optimal reconstruction of functions and linear functionals. Many of the results are base
Directory of Open Access Journals (Sweden)
Blackwell Emily J
2012-06-01
Full Text Available Abstract Background The use of electronic training devices for dog training is controversial. The aims of this study were to give an indication of the extent to which dog owners use these devices in England, identify factors associated with their use, and compare owner report of outcomes. A convenience sample of dog owners in England was used to identify numbers using electronic training devices and identify reasons for use. Factors associated with use of remote e-collars only were determined by comparing dogs trained using these devices with two control populations matched for reason of use (recall / chasing problems. Comparison groups were: those using other ‘negative reinforcement / positive punishment’ training techniques, and those using ‘positive reinforcement / negative punishment’ based methods. A multinominal logistic regression model was used to compare factors between categories of training method. Owner reported success for use was compared using chi-squared analysis. Results For England only, 3.3% (n = 133 owners reported using remote activated e-collars, 1.4% (n = 54 reported use of bark activated e-collars, and 0.9% (n = 36 reported using electronic boundary fences. In comparison with the e-collar group, owners using reward based training methods for recall / chasing were 2.8 times more likely to be female and 2.7 times less likely to have attended agility training. Owners using other aversive methods for recall / chasing were 2.8 times more likely to have attended puppy classes than those using e-collars. However, the model only explained 10% variance between groups. A significantly higher proportion of owners in the reward group reported training success than those in the e-collar group. Conclusions In conclusion, a fairly low proportion of owners select to use electronic training devices. For a population matched by reason for training method use, characteristics of dogs, including occurrence of undesired
Skorupski, Krzysztof
2015-05-01
Black carbon (BC) particles are a product of incomplete combustion of carbon-based fuels. One of the possibilities of studying the optical properties of BC structures is to use the DDA (Discrete Dipole Approximation) method. The main goal of this work was to investigate its accuracy and to approximate the most reliable simulation parameters. For the light scattering simulations the ADDA code was used and for the reference program the superposition T-Matrix code by Mackowski was selected. The study was divided into three parts. First, DDA simulations for a single particle (sphere) were performed. The results proved that the meshing algorithm can significantly affect the particle shape, and therefore, the extinction diagrams. The volume correction procedure is recommended for sparse or asymmetrical meshes. In the next step large fractal-like aggregates were investigated. When sparse meshes are used, the impact of the volume correction procedure cannot be easily predicted. In some cases it can even lead to more erroneous results. Finally, the optical properties of fractal-like aggregates composed of spheres in point contact were compared to much more realistic structures made up of connected, non-spherical primary particles.
Directory of Open Access Journals (Sweden)
Jingjing Feng
2016-01-01
Full Text Available In dynamic systems, some nonlinearities generate special connection problems of non-Z2 symmetric homoclinic and heteroclinic orbits. Such orbits are important for analyzing problems of global bifurcation and chaos. In this paper, a general analytical method, based on the undetermined Padé approximation method, is proposed to construct non-Z2 symmetric homoclinic and heteroclinic orbits which are affected by nonlinearity factors. Geometric and symmetrical characteristics of non-Z2 heteroclinic orbits are analyzed in detail. An undetermined frequency coefficient and a corresponding new analytic expression are introduced to improve the accuracy of the orbit trajectory. The proposed method shows high precision results for the Nagumo system (one single orbit; general types of non-Z2 symmetric nonlinear quintic systems (orbit with one cusp; and Z2 symmetric system with high-order nonlinear terms (orbit with two cusps. Finally, numerical simulations are used to verify the techniques and demonstrate the enhanced efficiency and precision of the proposed method.
Mozharovskiy, A. V.; Artemenko, A. A.; Mal'tsev, A. A.; Maslennikov, R. O.; Sevast'yanov, A. G.; Ssorin, V. N.
2015-11-01
We develop a combined method for calculating the characteristics of the integrated lens antennas for millimeter-wave wireless local radio-communication systems on the basis of the geometrical and physical optics approximations. The method is based on the concepts of geometrical optics for calculating the electromagnetic-field distribution on the lens surface (with allowance for multiple internal re-reflections) and physical optics for determining the antenna-radiated fields in the Fraunhofer zone. Using the developed combined method, we study various integrated lens antennas on the basis of the data on the used-lens shape and material and the primary-feed radiation model, which is specified analytically or by computer simulation. Optimal values of the cylindrical-extension length, which ensure the maximum antenna directivity equal to 19.1 and 23.8 dBi for the greater and smaller lenses, respectively, are obtained for the hemispherical quartz-glass lenses having the cylindrical extensions with radii of 7.5 and 12.5 mm. In this case, the scanning-angle range of the considered antennas is greater than ±20° for an admissible 2-dB decrease in the directivity of the deflected beam. The calculation results obtained using the developed method are confirmed by the experimental studies performed for the prototypes of the integrated quartz-glass lens antennas within the framework of this research.
ANDRE, Frédéric; HOU, Longfeng; SOLOVJOV, Vladimir P.
2016-01-01
The main restriction of k-distribution approaches for applications in radiative heat transfer in gaseous media arises from the use of a scaling or correlation assumption to treat non-uniform situations. It is shown that those cases can be handled exactly by using a multidimensional k-distribution that addresses the problem of spectral correlations without using any simplifying assumptions. Nevertheless, the approach cannot be suggested for engineering applications due to its computational cost. Accordingly, a more efficient method, based on the so-called Multi-Spectral Framework, is proposed to approximate the previous exact formulation. The model is assessed against reference LBL calculations and shown to outperform usual k-distribution approaches for radiative heat transfer in non-uniform media.
Directory of Open Access Journals (Sweden)
M. M. Rashidi
2012-01-01
Full Text Available In this study, a steady, incompressible, and laminar-free convective flow of a two-dimensional electrically conducting viscoelastic fluid over a moving stretching surface through a porous medium is considered. The boundary-layer equations are derived by considering Boussinesq and boundary-layer approximations. The nonlinear ordinary differential equations for the momentum and energy equations are obtained and solved analytically by using homotopy analysis method (HAM with two auxiliary parameters for two classes of visco-elastic fluid (Walters’ liquid B and second-grade fluid. It is clear that by the use of second auxiliary parameter, the straight line region in ℏ-curve increases and the convergence accelerates. This research is performed by considering two different boundary conditions: (a prescribed surface temperature (PST and (b prescribed heat flux (PHF. The effect of involved parameters on velocity and temperature is investigated.
Logic and human reasoning: an assessment of the deduction paradigm.
Evans, Jonathan St B T
2002-11-01
The study of deductive reasoning has been a major paradigm in psychology for approximately the past 40 years. Research has shown that people make many logical errors on such tasks and are strongly influenced by problem content and context. It is argued that this paradigm was developed in a context of logicist thinking that is now outmoded. Few reasoning researchers still believe that logic is an appropriate normative system for most human reasoning, let alone a model for describing the process of human reasoning, and many use the paradigm principally to study pragmatic and probabilistic processes. It is suggested that the methods used for studying reasoning be reviewed, especially the instructional context, which necessarily defines pragmatic influences as biases.
Directory of Open Access Journals (Sweden)
KUDRYAVTSEV Pavel Gennadievich
2015-02-01
Full Text Available The paper deals with possibilities to use quasi-homogenous approximation for discription of properties of dispersed systems. The authors applied statistical polymer method based on consideration of average structures of all possible macromolecules of the same weight. The equiations which allow evaluating many additive parameters of macromolecules and the systems with them were deduced. Statistical polymer method makes it possible to model branched, cross-linked macromolecules and the systems with them which are in equilibrium or non-equilibrium state. Fractal analysis of statistical polymer allows modeling different types of random fractal and other objects examined with the mehods of fractal theory. The method of fractal polymer can be also applied not only to polymers but also to composites, gels, associates in polar liquids and other packaged systems. There is also a description of the states of colloid solutions of silica oxide from the point of view of statistical physics. This approach is based on the idea that colloid solution of silica dioxide – sol of silica dioxide – consists of enormous number of interacting particles which are always in move. The paper is devoted to the research of ideal system of colliding but not interacting particles of sol. The analysis of behavior of silica sol was performed according to distribution Maxwell-Boltzmann and free path length was calculated. Using this data the number of the particles which can overcome the potential barrier in collision was calculated. To model kinetics of sol-gel transition different approaches were studied.
Prestack traveltime approximations
Alkhalifah, Tariq Ali
2012-05-01
Many of the explicit prestack traveltime relations used in practice are based on homogeneous (or semi-homogenous, possibly effective) media approximations. This includes the multifocusing, based on the double square-root (DSR) equation, and the common reflection stack (CRS) approaches. Using the DSR equation, I constructed the associated eikonal form in the general source-receiver domain. Like its wave-equation counterpart, it suffers from a critical singularity for horizontally traveling waves. As a result, I recasted the eikonal in terms of the reflection angle, and thus, derived expansion based solutions of this eikonal in terms of the difference between the source and receiver velocities in a generally inhomogenous background medium. The zero-order term solution, corresponding to ignoring the lateral velocity variation in estimating the prestack part, is free of singularities and can be used to estimate traveltimes for small to moderate offsets (or reflection angles) in a generally inhomogeneous medium. The higher-order terms include limitations for horizontally traveling waves, however, we can readily enforce stability constraints to avoid such singularities. In fact, another expansion over reflection angle can help us avoid these singularities by requiring the source and receiver velocities to be different. On the other hand, expansions in terms of reflection angles result in singularity free equations. For a homogenous background medium, as a test, the solutions are reasonably accurate to large reflection and dip angles. A Marmousi example demonstrated the usefulness and versatility of the formulation. © 2012 Society of Exploration Geophysicists.
A coastal ocean model with subgrid approximation
Walters, Roy A.
2016-06-01
A wide variety of coastal ocean models exist, each having attributes that reflect specific application areas. The model presented here is based on finite element methods with unstructured grids containing triangular and quadrilateral elements. The model optimizes robustness, accuracy, and efficiency by using semi-implicit methods in time in order to remove the most restrictive stability constraints, by using a semi-Lagrangian advection approximation to remove Courant number constraints, and by solving a wave equation at the discrete level for enhanced efficiency. An added feature is the approximation of the effects of subgrid objects. Here, the Reynolds-averaged Navier-Stokes equations and the incompressibility constraint are volume averaged over one or more computational cells. This procedure gives rise to new terms which must be approximated as a closure problem. A study of tidal power generation is presented as an example of this method. A problem that arises is specifying appropriate thrust and power coefficients for the volume averaged velocity when they are usually referenced to free stream velocity. A new contribution here is the evaluation of three approaches to this problem: an iteration procedure and two mapping formulations. All three sets of results for thrust (form drag) and power are in reasonable agreement.
International Nuclear Information System (INIS)
This document is a supplement to a ''Handbook for Cost Estimating'' (NUREG/CR-3971) and provides specific guidance for developing ''quick'' approximate estimates of the cost of implementing generic regulatory requirements for nuclear power plants. A method is presented for relating the known construction costs for new nuclear power plants (as contained in the Energy Economic Data Base) to the cost of performing similar work, on a back-fit basis, at existing plants. Cost factors are presented to account for variations in such important cost areas as construction labor productivity, engineering and quality assurance, replacement energy, reworking of existing features, and regional variations in the cost of materials and labor. Other cost categories addressed in this handbook include those for changes in plant operating personnel and plant documents, licensee costs, NRC costs, and costs for other government agencies. Data sheets, worksheets, and appropriate cost algorithms are included to guide the user through preparation of rough estimates. A sample estimate is prepared using the method and the estimating tools provided
Beyond the random phase approximation
DEFF Research Database (Denmark)
Olsen, Thomas; Thygesen, Kristian S.
2013-01-01
We assess the performance of a recently proposed renormalized adiabatic local density approximation (rALDA) for ab initio calculations of electronic correlation energies in solids and molecules. The method is an extension of the random phase approximation (RPA) derived from time-dependent density...
Energy Technology Data Exchange (ETDEWEB)
Chalasani, P.; Saias, I. [Los Alamos National Lab., NM (United States); Jha, S. [Carnegie Mellon Univ., Pittsburgh, PA (United States)
1996-04-08
As increasingly large volumes of sophisticated options (called derivative securities) are traded in world financial markets, determining a fair price for these options has become an important and difficult computational problem. Many valuation codes use the binomial pricing model, in which the stock price is driven by a random walk. In this model, the value of an n-period option on a stock is the expected time-discounted value of the future cash flow on an n-period stock price path. Path-dependent options are particularly difficult to value since the future cash flow depends on the entire stock price path rather than on just the final stock price. Currently such options are approximately priced by Monte carlo methods with error bounds that hold only with high probability and which are reduced by increasing the number of simulation runs. In this paper the authors show that pricing an arbitrary path-dependent option is {number_sign}-P hard. They show that certain types f path-dependent options can be valued exactly in polynomial time. Asian options are path-dependent options that are particularly hard to price, and for these they design deterministic polynomial-time approximate algorithms. They show that the value of a perpetual American put option (which can be computed in constant time) is in many cases a good approximation to the value of an otherwise identical n-period American put option. In contrast to Monte Carlo methods, the algorithms have guaranteed error bounds that are polynormally small (and in some cases exponentially small) in the maturity n. For the error analysis they derive large-deviation results for random walks that may be of independent interest.
Defeasibility in Legal Reasoning
Sartor, Giovanni
2009-01-01
I shall first introduce the idea of reasoning, and of defeasible reasoning in particular. I shall then argue that cognitive agents need to engage in defeasible reasoning for coping with a complex and changing environment. Consequently, defeasibility is needed in practical reasoning, and in particular in legal reasoning
一种基于本体推理的业务特征获取方法%Service Feature Acquisition Method Based on Ontology Reasoning
Institute of Scientific and Technical Information of China (English)
盖炳帅; 王劲林; 刘学
2013-01-01
In the field of service data sampling, this paper provides a service feature acquisition method based on ontology reasoning to solve the problem of lacking automatic methods for data sampling item acquisition. Firstly, this method eliminates OWL conflicts in the service ontology using Racer and eliminates SWRL conflicts in the service ontology using JESS. Secondly, this method acquests explicit service features by ontology parsing and implicit service features in the service ontology using rules designed based on the ontology-based service model. Lastly, this method generates service data sampling items with the features in the service ontology. The analysis result of the example shows that this method can make data sampling item acquisition process automaticly.%在业务数据采集领域中,针对采集数据项不能自动获取的问题,提出一种利用本体推理的业务特征获取方法.在方法中,首先用Racer推理机消除业务本体中存在的OWL语义冲突,采用JESS推理机消除业务本体中存在的SWRL语义冲突,然后通过本体解析获取明显业务特征,并基于本体业务模型设计隐含业务特征获取规则,获取隐含业务特征,最后结合业务本体生成业务采集数据项集合.实例仿真结果表明,改进方法能够实现自动化的业务采集数据项获取过程.
Leike, Reimar H
2016-01-01
In Bayesian statistics probability distributions express beliefs. However, for many problems the beliefs cannot be computed analytically and approximations of beliefs are needed. We seek a ranking function that quantifies how "embarrassing" it is to communicate a given approximation. We show that there is only one ranking under the requirements that (1) the best ranked approximation is the non-approximated belief and (2) that the ranking judges approximations only by their predictions for actual outcomes. We find that this ranking is equivalent to the Kullback-Leibler divergence that is frequently used in the literature. However, there seems to be confusion about the correct order in which its functional arguments, the approximated and non-approximated beliefs, should be used. We hope that our elementary derivation settles the apparent confusion. We show for example that when approximating beliefs with Gaussian distributions the optimal approximation is given by moment matching. This is in contrast to many su...
Optimal Filter Approximations in Conditionally Gaussian Pairwise Markov Switching Models
Abbassi, N; Benboudjema, D; Derrode, Stéphane; Pieczynski, W
2015-01-01
—We consider a general triplet Markov Gaussian linear system (X, R, Y), where X is an hidden continuous random sequence, R is an hidden discrete Markov chain, Y is an observed continuous random sequence. When the triplet (X, R, Y) is a classical " Conditionally Gaussian Linear State-Space Model " (CGLSSM), the mean square error optimal filter is not workable with a reasonable complexity and different approximate methods, e.g. based on particle filters, are used. We propose two contributions. ...
Zhao, ShuanFeng; Liang, Lin; Xu, GuangHua; Wang, Jing; Zhang, WenMing
2013-10-01
Spalling or pitting is the main manifestation of fault development in a bearing during the earlier stages. Previous studies indicated that the vibration signal of a bearing with a spall-like defect may be composed of two parts; the first part originates from the entry of the rolling element into the spall-like area, and the second part refers to the exit from the fault region. The quantitative diagnosis of a spall-like fault of the rolling element bearing can be realised if the entry-exit event times can be accurately calculated. However, the vibration signal of a faulty bearing is usually non-stationary and non-linear with strong background noise interference. Meanwhile, the signal energy from the early spall region is too low to accurately register the features of the entry-exit event in the time domain. In this work, the approximate entropy (ApEn) method and empirical mode decomposition (EMD) are applied to clearly separate the entry-exit events, and thus the size of the spall-like fault is estimated. First, the original acceleration vibration signal is decomposed by EMD, and some useful intrinsic mode function (IMF) components are obtained. Second, the concept of IMF-ApEn is introduced, which can directly reflect the complexity of the IMFs using the actual vibration signal. The IMF-ApEn distributions of different noise signals illustrate that the process of complexity changes when a full spectrum process is split into its IMFs. Third, a unit white noise IMF-ApEn distribution template serves as a sieve to extract the (effective intrinsic mode functions) EIMF components, and thus the entry and exit events in the response signal are distinguished. The IMF-ApEn method is further compared with a previous method (N. Sawalhi's method) to test its superiority. The dynamic effects are investigated when the ball element enters a spall-like region by computer simulation. The simulation and the experimental results show that the approach to the quantitative diagnosis of a
突发事件情境重构中的模糊规则推理方法%Fuzzy rules reasoning method in emergency context reconstruction
Institute of Scientific and Technical Information of China (English)
王颜新; 李向阳; 徐磊
2012-01-01
突发事件的复杂情境涉及自然、人文、组织、资源等因素,提升对事件情境的认知能力,分析事件发展的可能态势并建立有效应对是“情景-应对”研究的重要课题.利用情境重构方法建立突发事件的参考情景,可以弥补突发事件实时信息的不完备性,是进行态势预测并建立应对决策的有效方法.在分析事件情境要素的构成以及情境与情景构成关系基础上,构建了由情境要素识别到建立情景描述模糊规则,再到通过规则推理方法建立事件态势分析的参考情境库的研究思路.给出了情境重构中的模糊规则设计与案例.%Complex context of emergencies, involving natural, cultural, organizational, resource and other factors, is fundamental to identify the activities and scenarios. Based on analysis of relations between event context and scenario changing, elements of context are defined in perspective of structure and transforma-tion. Research ideas are described from cognition of context elements to the description of context, and to building fuzzy rules of scenario reasoning. For context elements, a fuzzy rule for scenario changing in multi-context is designed, and a method based on fuzzy rules reasoning for emergency scenario planning under situation of incomplete information is proposed.
Bin Qin
2014-01-01
Relationships between fuzzy relations and fuzzy topologies are deeply researched. The concept of fuzzy approximating spaces is introduced and decision conditions that a fuzzy topological space is a fuzzy approximating space are obtained.
Rasin, A
1994-01-01
We discuss the idea of approximate flavor symmetries. Relations between approximate flavor symmetries and natural flavor conservation and democracy models is explored. Implications for neutrino physics are also discussed.
Directory of Open Access Journals (Sweden)
Patricia A. Poulin
2016-01-01
Full Text Available Background. Chronic pain (CP accounts for 10–16% of emergency department (ED visits, contributing to ED overcrowding and leading to adverse events. Objectives. To describe patients with CP attending the ED and identify factors contributing to their visit. Methods. We used a mixed-method design combining interviews and questionnaires addressing pain, psychological distress, signs of opioid misuse, and disability. Participants were adults who attended the EDs of a large academic tertiary care center for their CP problem. Results. Fifty-eight patients (66% women; mean age 46.5, SD = 16.9 completed the study. The most frequently cited reason (60% for ED visits was inability to cope with pain. Mental health problems were common, including depression (61% and anxiety (45%. Participants had questions about the etiology of their pain, concerns about severe pain-related impairment, and problems with medication renewals or efficacy and sometimes felt invalidated in the ED. Although most participants had a primary care physician, the ED was seen as the only or best option when pain became unmanageable. Conclusions. Patients with CP visiting the ED often present with complex difficulties that cannot be addressed in the ED. Better access to interdisciplinary pain treatment is needed to reduce the burden of CP on the ED.
International Nuclear Information System (INIS)
A theoretical study in fuzzy reasoning on Horn Set is presented in this paper. The authors first introduce the concepts of λ-Horn Set of clauses and λ-Input Half Lock deduction. They then use the λ-resolution method to discuss fuzzy reasoning on λ-Horn set of clauses. It is proved that the proposed λ-Input Half Lock resolution method is complete with the rules in certain format
Approximation of distributed delays
Lu, Hao; Eberard, Damien; Simon, Jean-Pierre
2010-01-01
We address in this paper the approximation problem of distributed delays. Such elements are convolution operators with kernel having bounded support, and appear in the control of time-delay systems. From the rich literature on this topic, we propose a general methodology to achieve such an approximation. For this, we enclose the approximation problem in the graph topology, and work with the norm defined over the convolution Banach algebra. The class of rational approximates is described, and a constructive approximation is proposed. Analysis in time and frequency domains is provided. This methodology is illustrated on the stabilization control problem, for which simulations results show the effectiveness of the proposed methodology.
Stereotypical Reasoning: Logical Properties
Lehmann, Daniel
2002-01-01
Stereotypical reasoning assumes that the situation at hand is one of a kind and that it enjoys the properties generally associated with that kind of situation. It is one of the most basic forms of nonmonotonic reasoning. A formal model for stereotypical reasoning is proposed and the logical properties of this form of reasoning are studied. Stereotypical reasoning is shown to be cumulative under weak assumptions.
Proportional Reasoning and the Visually Impaired
Hilton, Geoff; Hilton, Annette; Dole, Shelley L.; Goos, Merrilyn; O'Brien, Mia
2012-01-01
Proportional reasoning is an important aspect of formal thinking that is acquired during the developmental years that approximate the middle years of schooling. Students who fail to acquire sound proportional reasoning often experience difficulties in subjects that require quantitative thinking, such as science, technology, engineering, and…
Directory of Open Access Journals (Sweden)
Marta Lucia de Oliveira Carvalho
2005-10-01
Full Text Available OBJETIVO: Identificar as representações sobre os métodos contraceptivos que poderiam ser alternativas à esterilização, para um grupo de mulheres esterilizadas, visando a entender os motivos de rejeição a esses métodos. MÉTODOS: Trata-se de trabalho descritivo, qualitativo, cuja população estudada foi constituída por 31 mulheres esterilizadas, aleatoriamente selecionadas da listagem de pacientes atendidas pelo Programa de Planejamento Familiar de um ambulatório de um hospital universitário. As informações foram obtidas das mulheres estudadas por meio de entrevistas semi-estruturadas. As transcrições foram analisadas segundo o método de Análise de Conteúdo. RESULTADOS: A rejeição aos métodos contraceptivos esteve baseada em representações resultantes de informações técnicas recebidas em serviços de saúde, de vivências anteriores com esses métodos ou de informações recebidas do meio social. A rejeição aos métodos hormonais e DIU baseou-se principalmente em representações de baixa inocuidade; os métodos comportamentais (Tabela, Billings foram rejeitados por representações de baixa eficácia; os métodos de barreira (diafragma e camisinha, por dificuldades no uso desses métodos relacionados a padrões culturais de exercício da sexualidade e representações de baixa eficácia. CONCLUSÕES: A opção pela esterilização feminina pode ser indicativa de rejeição às alternativas contraceptivas oferecidas pelos serviços de saúde. Os profissionais da área de saúde reprodutiva devem aprofundar seu conhecimento sobre os fatores pessoais, socioeconômicos e culturais que podem influenciar as mulheres na procura por um método contraceptivo que assegure maior controle de sua própria fecundidade.OBJECTIVE: To identify the representations of contraceptive methods within a group of sterilized women, aiming at understanding the reasons why they refused those methods. METHODS: A descriptive qualitative study
Institute of Scientific and Technical Information of China (English)
YueShihong; ZhangKecun
2002-01-01
In a dot product space with the reproducing kernel (r. k. S. ) ,a fuzzy system with the estimation approximation errors is proposed ,which overcomes the defect that the existing fuzzy control system is difficult to estimate the errors of approximation for a desired function,and keeps the characteristics of fuzzy system as an inference approach. The structure of the new fuzzy approximator benefits a course got by other means.
Approximation techniques for engineers
Komzsik, Louis
2006-01-01
Presenting numerous examples, algorithms, and industrial applications, Approximation Techniques for Engineers is your complete guide to the major techniques used in modern engineering practice. Whether you need approximations for discrete data of continuous functions, or you''re looking for approximate solutions to engineering problems, everything you need is nestled between the covers of this book. Now you can benefit from Louis Komzsik''s years of industrial experience to gain a working knowledge of a vast array of approximation techniques through this complete and self-contained resource.
Expectation Consistent Approximate Inference
DEFF Research Database (Denmark)
Opper, Manfred; Winther, Ole
2005-01-01
We propose a novel framework for approximations to intractable probabilistic models which is based on a free energy formulation. The approximation can be understood from replacing an average over the original intractable distribution with a tractable one. It requires two tractable probability dis...
Coates, Daniel Justin
2012-01-01
In this dissertation I develop a theory of practical reasons as such, and then I extend that theory to specifically moral reasons. According to the theory of practical reasons that I develop in Part I, the existence and weight of an agent's reason to act in a particular way depends on an agent's motivational states--specifically those motivational states issuing from practical orientations that play some role in structuring the agent's practical identity. I then argue that this account of p...
DEFF Research Database (Denmark)
Tønder, Lars
2014-01-01
This article takes up recent discussions of nature and the sensorium in order to rethink public reason in deeply divided societies. The aim is not to reject the role of reason-giving but rather to infuse it with new meaning, bringing the reasonable back to its sensorially inflected circumstances....
McHugh, Conor; Way, Jonathan
2014-01-01
Among the many important contributions of John Broome’s Rationality Through Reasoning is an account of what reasoning is and what makes reasoning correct. In this paper we raise some problems for both of these accounts and recommend an alternative approach.
Approximate Implicitization Using Linear Algebra
Directory of Open Access Journals (Sweden)
Oliver J. D. Barrowclough
2012-01-01
Full Text Available We consider a family of algorithms for approximate implicitization of rational parametric curves and surfaces. The main approximation tool in all of the approaches is the singular value decomposition, and they are therefore well suited to floating-point implementation in computer-aided geometric design (CAGD systems. We unify the approaches under the names of commonly known polynomial basis functions and consider various theoretical and practical aspects of the algorithms. We offer new methods for a least squares approach to approximate implicitization using orthogonal polynomials, which tend to be faster and more numerically stable than some existing algorithms. We propose several simple propositions relating the properties of the polynomial bases to their implicit approximation properties.
Weighted approximation with varying weight
Totik, Vilmos
1994-01-01
A new construction is given for approximating a logarithmic potential by a discrete one. This yields a new approach to approximation with weighted polynomials of the form w"n"(" "= uppercase)P"n"(" "= uppercase). The new technique settles several open problems, and it leads to a simple proof for the strong asymptotics on some L p(uppercase) extremal problems on the real line with exponential weights, which, for the case p=2, are equivalent to power- type asymptotics for the leading coefficients of the corresponding orthogonal polynomials. The method is also modified toyield (in a sense) uniformly good approximation on the whole support. This allows one to deduce strong asymptotics in some L p(uppercase) extremal problems with varying weights. Applications are given, relating to fast decreasing polynomials, asymptotic behavior of orthogonal polynomials and multipoint Pade approximation. The approach is potential-theoretic, but the text is self-contained.
Value Function Approximation or Stopping Time Approximation
DEFF Research Database (Denmark)
Stentoft, Lars
2014-01-01
In their 2001 paper, Longstaff and Schwartz suggested a method for American option pricing using simulation and regression, and since then this method has rapidly gained importance. However, the idea of using regression and simulation for American option pricing was used at least as early as 1996......, by Carriere. In this paper, we provide a thorough comparison of these two methods and relate them to the work of Tsitsiklis and Van Roy. Although the methods are often considered to be similar, this analysis allows us to point out an important but often overlooked difference between them. We further show that...
Tejero, A.; Chavez, R. E.
2001-12-01
The Born approximation method has been commonly employed to study the electromagnetic field response. Other interpretative techniques have benn employed based upon the Born Approximation, like the extended Born approximation (EBA). This method employs the total field, instead of the primary field. Also, the Quasi Linear Approximation method (QLA) is an extension of EVA. In the present work, we propose an alternative technique, which employs the Born Approximation using variable background conductivities (BAVBC). The Green function is represented as a Born perturbation of zero order. Such that, the reference medium conductivity is a parameter selected according the working frequency. A similar procedure has been reported for stratified 1D-earth seismic models. This technique (BAVBC) has been applied to model computational models with reasonable results, as compared with available computational packages in the market. This method permits variations in the conductivity contrast of up to 80%, which provides solutions with 30% error, with respect of the analytical solution.
Truth-value transmittal fuzzy reasoning interpolator
Institute of Scientific and Technical Information of China (English)
YAN Jianping; LEUNG Yee
2005-01-01
In this paper, we firstly associate fuzzy reasoning algorithm with the interpolation algorithm and discuss the limitation of defuzzification methods used commonly in the fuzzy reasoning algorithm. Secondly, we give a new fuzzy reasoning algorithm in case of single input, called the truth-value transmittal method, and discuss its properties. Finally, we analyze the rationality to adopy the truth-value transmittal method as the defuzzification method of full implication triple I method, and show that although CRI and triple I fuzzy reasoning method are different from fuzzy output set, they are uniform finally under the truth-value transmittal defuzzification method.
Institute of Scientific and Technical Information of China (English)
胡理; 粱博; 汤学宏
2011-01-01
根据正负弯矩进行梁的正截面配筋设计时，由于不知道可能存在的可用于受压钢筋的配筋面积，梁的顶部和底部纵筋的计算一般由正负弯矩的最不利效应决定，不考虑由于构造或计算可能存在的受压钢筋的影响。根据本文的分析，在配筋率较大的情况下，如果不考虑受压钢筋的有利影响，将会造成材料浪费。本文提出了一种在不能确定受压钢筋面积时，通过简单的内力比较后，合理地考虑梁的受压钢筋的配筋设计方案。由本文的分析可以得出结论．这种配筋设计方案的设计结果确实可以达到节省材料的目的．%When reinforcing bars for concrete beam according to positive and negative moments, generally, the top and bottom longitudinal reinforcement are determined only by the most adverse effects of the positive and negative moments and the influence of compressive reinforcement is ignored in this calculation, because of not knowing the area of reinforcement which may be used as compressive bar. According to the analysis of this paper, when the reinforcement ratio is high, if not considering the beneficial effects of compressive reinforcement, the waste of materials will be caused. This paper presents a reinforcement design method which can reasonably consider the influence of compressive bar by simple comparison of moments, when not knowing the area of compressive reinforcement. This analysis can concluded that the results by the method in the paper can really achieve the purpose of saving material.
Legendre rational approximation on the whole line
Institute of Scientific and Technical Information of China (English)
GUO; Benyu; WANG; Zhongqing
2004-01-01
The Legendre rational approximation is investigated. Some approximation results are established, which form the mathematical foundation of a new spectral method on the whole line. A model problem is considered. Numerical results show the efficiency of this new approach.
Energy Technology Data Exchange (ETDEWEB)
Cartier, J
2006-04-15
This thesis focuses on mathematical analysis, numerical resolution and modelling of the transport equations. First of all, we deal with numerical approximation of the solution of the transport equations by using a mixed-hybrid scheme. We derive and study a mixed formulation of the transport equation, then we analyse the related variational problem and present the discretization and the main properties of the scheme. We particularly pay attention to the behavior of the scheme and we show its efficiency in the diffusion limit (when the mean free path is small in comparison with the characteristic length of the physical domain). We present academical benchmarks in order to compare our scheme with other methods in many physical configurations and validate our method on analytical test cases. Unstructured and very distorted meshes are used to validate our scheme. The second part of this thesis deals with two transport problems. The first one is devoted to the study of diffusion due to boundary conditions in a transport problem between two plane plates. The second one consists in modelling and simulating radiative transfer phenomenon in case of the industrial context of inertial confinement fusion. (author)
The Karlqvist approximation revisited
Tannous, C.
2015-01-01
The Karlqvist approximation signaling the historical beginning of magnetic recording head theory is reviewed and compared to various approaches progressing from Green, Fourier, Conformal mapping that obeys the Sommerfeld edge condition at angular points and leads to exact results.
Approximations in Inspection Planning
DEFF Research Database (Denmark)
Engelund, S.; Sørensen, John Dalsgaard; Faber, M. H.;
2000-01-01
Planning of inspections of civil engineering structures may be performed within the framework of Bayesian decision analysis. The effort involved in a full Bayesian decision analysis is relatively large. Therefore, the actual inspection planning is usually performed using a number of approximations....... One of the more important of these approximations is the assumption that all inspections will reveal no defects. Using this approximation the optimal inspection plan may be determined on the basis of conditional probabilities, i.e. the probability of failure given no defects have been found...... by the inspection. In this paper the quality of this approximation is investigated. The inspection planning is formulated both as a full Bayesian decision problem and on the basis of the assumption that the inspection will reveal no defects....
Directory of Open Access Journals (Sweden)
Malvina Baica
1985-01-01
Full Text Available The author uses a new modification of Jacobi-Perron Algorithm which holds for complex fields of any degree (abbr. ACF, and defines it as Generalized Euclidean Algorithm (abbr. GEA to approximate irrationals.
An approximation technique for jet impingement flow
Energy Technology Data Exchange (ETDEWEB)
Najafi, Mahmoud; Fincher, Donald [Kent State University Ashtabula Department of Mathematical Sciences (United States); Rahni, Taeibi; Javadi, KH. [Department of Aerospace Engineering, Sharif University of Technology (Iran, Islamic Republic of); Massah, H. [Acoustic Research Center, Institute of Applied Physics (Iran, Islamic Republic of)
2015-03-10
The analytical approximate solution of a non-linear jet impingement flow model will be demonstrated. We will show that this is an improvement over the series approximation obtained via the Adomian decomposition method, which is itself, a powerful method for analysing non-linear differential equations. The results of these approximations will be compared to the Runge-Kutta approximation in order to demonstrate their validity.
Approximation Behooves Calibration
DEFF Research Database (Denmark)
da Silva Ribeiro, André Manuel; Poulsen, Rolf
2013-01-01
Calibration based on an expansion approximation for option prices in the Heston stochastic volatility model gives stable, accurate, and fast results for S&P500-index option data over the period 2005–2009.......Calibration based on an expansion approximation for option prices in the Heston stochastic volatility model gives stable, accurate, and fast results for S&P500-index option data over the period 2005–2009....
Gautschi, Walter; Rassias, Themistocles M
2011-01-01
Approximation theory and numerical analysis are central to the creation of accurate computer simulations and mathematical models. Research in these areas can influence the computational techniques used in a variety of mathematical and computational sciences. This collection of contributed chapters, dedicated to renowned mathematician Gradimir V. Milovanovia, represent the recent work of experts in the fields of approximation theory and numerical analysis. These invited contributions describe new trends in these important areas of research including theoretic developments, new computational alg
Ultrafast Approximation for Phylogenetic Bootstrap
Bui Quang Minh, [No Value; Nguyen, Thi; von Haeseler, Arndt
2013-01-01
Nonparametric bootstrap has been a widely used tool in phylogenetic analysis to assess the clade support of phylogenetic trees. However, with the rapidly growing amount of data, this task remains a computational bottleneck. Recently, approximation methods such as the RAxML rapid bootstrap (RBS) and
Pinnock, Ralph; Welch, Paul
2014-04-01
Errors in clinical reasoning continue to account for significant morbidity and mortality, despite evidence-based guidelines and improved technology. Experts in clinical reasoning often use unconscious cognitive processes that they are not aware of unless they explain how they are thinking. Understanding the intuitive and analytical thinking processes provides a guide for instruction. How knowledge is stored is critical to expertise in clinical reasoning. Curricula should be designed so that trainees store knowledge in a way that is clinically relevant. Competence in clinical reasoning is acquired by supervised practice with effective feedback. Clinicians must recognise the common errors in clinical reasoning and how to avoid them. Trainees can learn clinical reasoning effectively in everyday practice if teachers provide guidance on the cognitive processes involved in making diagnostic decisions.
Politzer, Guy
2007-01-01
This paper reviews the psychological investigation of reasoning with conditionals, putting an emphasis on recent work. In the first part, a few methodological remarks are presented. In the second part, the main theories of deductive reasoning (mental rules, mental models, and the probabilistic approach) are considered in turn; their content is summarised and the semantics they assume for if and the way they explain formal conditional reasoning are discussed, in particular in the light of expe...
Institute of Scientific and Technical Information of China (English)
曹立明
1990-01-01
By the similarity between the syllogism in logic and a path proposition in graph theory,a new concept,fuzzy reasoning graph G has been given in this paper. Transitive closure has been studied and used to do reasoning related to self-loop in G,and an algorithm has been designed to cope with reasoning in other cycles in G. Both approaches are applicable and efficient.
Mean-field approximation for spacing distribution functions in classical systems
González, Diego Luis; Pimpinelli, Alberto; Einstein, T. L.
2012-01-01
We propose a mean-field method to calculate approximately the spacing distribution functions p(n)(s) in one-dimensional classical many-particle systems. We compare our method with two other commonly used methods, the independent interval approximation and the extended Wigner surmise. In our mean-field approach, p(n)(s) is calculated from a set of Langevin equations, which are decoupled by using a mean-field approximation. We find that in spite of its simplicity, the mean-field approximation provides good results in several systems. We offer many examples illustrating that the three previously mentioned methods give a reasonable description of the statistical behavior of the system. The physical interpretation of each method is also discussed.
Zhang, Shen; Wang, Hongwei; Kang, Wei; Zhang, Ping; He, X. T.
2016-04-01
An extended first-principles molecular dynamics (FPMD) method based on Kohn-Sham scheme is proposed to elevate the temperature limit of the FPMD method in the calculation of dense plasmas. The extended method treats the wave functions of high energy electrons as plane waves analytically and thus expands the application of the FPMD method to the region of hot dense plasmas without suffering from the formidable computational costs. In addition, the extended method inherits the high accuracy of the Kohn-Sham scheme and keeps the information of electronic structures. This gives an edge to the extended method in the calculation of mixtures of plasmas composed of heterogeneous ions, high-Z dense plasmas, lowering of ionization potentials, X-ray absorption/emission spectra, and opacities, which are of particular interest to astrophysics, inertial confinement fusion engineering, and laboratory astrophysics.
Institute of Scientific and Technical Information of China (English)
许艳琼
2009-01-01
文章介绍了合理低价中标法的评标方法,阐述了对于这种评标方法投标人应采取的报价策略.%The article introduced the reasonable low price is selected method the evaluation of tenders method, elaborated should adopt the quoted price strategy regarding this kind of evaluation of tenders method tenderer.
Approximation of Surfaces by Cylinders
DEFF Research Database (Denmark)
Randrup, Thomas
1998-01-01
We present a new method for approximation of a given surface by a cylinder surface. It is a constructive geometric method, leading to a monorail representation of the cylinder surface. By use of a weighted Gaussian image of the given surface, we determine a projection plane. In the orthogonal...... projection of the surface onto this plane, a reference curve is determined by use of methods for thinning of binary images. Finally, the cylinder surface is constructed as follows: the directrix of the cylinder surface is determined by a least squares method minimizing the distance to the points...
DEFF Research Database (Denmark)
Bieniasz, Leslaw K.; Østerby, Ole; Britz, Dieter
1995-01-01
We extend the analysis of the stepwise numerical stability of the classic explicit, fully implicit and Crank-Nicolson finite difference algorithms for electrochemical kinetic simulations, to the multipoint gradient approximations at the electrode. The discussion is based on the matrix method of...